TY - CONF A1 - Fellinger, Tim-Patrick T1 - Improved Hard Carbon Anodes for Na-ion Batteries by Interface Modification N2 - The current strong interest in electromotive mobility and the need to transition to an energy grid with sustainable storage devices has led to a renewed interest in sodium ion batteries (SIBs). Amorphous disordered carbons such as hard carbons (HCs) are promising candidates for high-capacity negative electrode materials in SIBs. Their high capacities, however, are often accompanied with high irreversible capacity losses during the initial cycles,[1] while low initial losses are accompanied with moderate capacities.[2] In our research we are aiming at morphologically improved carbons to reduce irreversible losses using a core-shell concept.[3] We investigated different methods to obtain core-shell structures with improved interfaces to restrict SEI formation to the external particle surface, while leveraging the Na storage potential of porous carbon core materials. With a simple and scalable chemical vapour deposition we obtained a 190-fold decrease in surface roughness, resulting in drastically reduced first cycle losses. Interestingly, the sodiation capacity at the same time increased revealing the interference of excessive SEI formation with the storage process within the particles. T2 - ECS Spring Meeting 2025 CY - Montreal, Canada DA - 18.05.2025 KW - Natrium-Ionen-Batterien KW - Synthetische Anoden KW - Kohlenstoff PY - 2025 AN - OPUS4-64911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Designing Core-Shell Carbon Materials for High-Performance Sodium-Ion Battery Anode N2 - Increasing prices of the material basis for lithium-ion batteries caused by limited production capacities or resource abundance has led to a renewed interest in sodium ion batteries (SIBs). Therein, amorphous disordered carbons such as hard carbons (HCs) are promising candidates for high-capacity negative electrode materials in SIBs. Their high capacities, however, are often accompanied with high irreversible capacity losses during the initial cycles,[1] while low initial losses are mostly accompanied with moderate capacities.[2] In our research we are aiming at morphologically improved carbons to reduce irreversible losses using a core-shell concept, leading to spacial separation of the reversible storage and unfavorable side reactions.[3] We investigated different methods to obtain core-shell structures with improved interfaces to restrict SEI formation to the external particle surface, while leveraging the Na storage potential of porous carbon core materials. With a simple and scalable chemical vapour deposition we obtained a 190-fold decrease in surface roughness, resulting in drastically reduced first cycle losses. Interestingly, the sodiation capacity at the same time increased to 400 mAh/g revealing the interference of excessive SEI formation with the storage process within the particles. T2 - International Carbon Conference 2025 CY - Saint Malo, France DA - 29.06.2025 KW - Sodium-Ion-Batteries KW - Hard Carbons KW - Synthetic Anodes KW - Carbon PY - 2025 AN - OPUS4-64907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Sustainable energy materials and circularity N2 - Li-ion batteries (LIB) are the dominant energy storage technology and present in electrified transportation, electronic devices as well as robotics. This is due to their high energy density (300 watt-hours per kilogram), low self-discharge (1.5-2% per month), long storage life (10 years) and cyclability (500-2000 cycles). Unfortunately, these batteries require the use of scarce, toxic and unethically resourced materials for their fabrication. Furthermore, it is expected an increase of 26 million units of LIB on electric vehicles by 2030 generating a large amount of waste in a very near future. However, those end-of-life batteries can be considered an important source of metals and materials (electrolytes, binders, anodes) to be reused in other applications or incorporated in the battery supply chain. This also pushes the need to redesign the LIB components and other sustainable technologies using low-cost materials. The focus of this symposium is to bring together experts from around the world to discuss the latest advancements in sustainability of battery technologies and their impact on the future landscape of our society and environment. During the symposium, speakers will present recent research and developments in solving future and present problems derived from the exponential demand of LIB manufacturing T2 - Mat-Sus Spring Meeting 2025 CY - Sevilla, Spain DA - 03.03.2025 KW - CRM-free KW - Sustainability KW - Energy Materials PY - 2025 AN - OPUS4-64915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Molekularsiebende Kohlenstoffe als hochkapazitive und stabile Anoden in Natrium-Ionen-Batterien N2 - In dem Vortrag wird ein Fortschrittsbericht über die laufenden Arbeiten im BMBF-geförderten Verbundprojekt „Dialysorb“ gegeben. Nach einer kurzen Schilderung der Arbeitspaketstruktur und den Arbeitspaketinhalten werden einzelne wissenschaftliche Ergebnisse genannt und kurz diskutiert. So gelang es hier u.a. hochporöse Materialien mittels Gasphasenabscheidung von Kohlenstoffverbindungen derart zu modifizieren, dass nur noch ein Bruchteil der Porosität mittels Gassorption messbar ist. Elektrochemische Sodiierungs-/Dessodiierungsergebnisse deuten darauf hin, dass die Porosität im Kern der Materialien erhalten ist, da die reversible Sodiierungskapazität deutlich erhöht ist. Abschließend werden folgende Arbeitschritte erläutert und der Vortrag zur Diskussion gestellt. T2 - BMBF-Statusmeeting B@TS 2025 CY - Cologne, Germany DA - 07.04.2025 KW - Natrium-Ionen-Batterien KW - Synthetische Anoden KW - Kohlenstoff PY - 2025 AN - OPUS4-64906 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Leveraging the Potential of Na-Ion-Batteries with Tailormade Anodes N2 - Research progress on synthetic hard carbon anodes was suggested as key technology to leverage the potential of sodium ion batteries. The background, progress and market size of sodium ion batteries was presented and the relevance of producing such materials in terms of a business case was suggested. T2 - HWR Entrepreneural Workshop 2025 CY - Berlin, Germany DA - 18.10.2025 KW - Natrium-Ionen-Batterien KW - Synthetische Anoden KW - Kohlenstoff PY - 2025 AN - OPUS4-64909 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Pedersen, Angus T1 - Mg-Templated Porosity as a Descriptor of Activity and Durability in ZIF-Derived Fe–N–C O2 Reduction Catalysts - Dataset N2 - Atomically dispersed Fe in N-doped carbon (Fe-N-C) catalysts are leading platinum-group-metal-free candidates for the O2 reduction reaction in proton exchange membrane fuel cells (PEMFCs). Zeolitic imidazolate framework (ZIF-8) derived Fe-N-C present the most promising performance; however, they possess a narrow distribution of small micropores, which limits active site accessibility. Here, to induce hierarchical porosity in Fe-N-C, we report a systematic study on MgCl₂·6H₂O-templated ZIF-8-derived Fe-N-C catalysts for the O2 reduction reaction. MgCl₂·6H₂O addition induced complete Zn removal, collapse of the ZIF-8 framework, and formation of large micro- and mesopores, with graphene-like structures. N content was markedly reduced, with conversion from pyridinic to pyrrolic N species. Rotating disc electrode tests showed a progressive increase in O2 reduction activity with MgCl₂·6H₂O, which is strongly correlated (R2 = 0.98) to the formation of large micropores and small mesopores (1-4 nm). This introduces a clear structure-activity design principle for Fe-N-Cs. The enhanced Fe-N-C porosity also leads to increased degradation rates under accelerated stress test conditions, which we attributed to the oxidation of disordered carbon domains and active Fe loss. This study highlights a key trade-off between porosity-driven O2 reduction activity and durability in Fe-N-C catalysts. KW - Single atom KW - Zeolitic imidazolate framework KW - Oxygen reduction PY - 2026 DO - https://doi.org/10.26272/opus4-65228 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-65228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Lee, Woojin T1 - Impact of Coating and Drying on Electrochemical Properties of Core-Shell Carbon Materials N2 - Due to the heavy overuse of fossil energy sources since the last couple of centuries, a range of serious concerns such as depletion of fossil fuels and climate change that is driven by extensive carbon dioxide (CO2) emission has risen. Rechargeable batteries have surged as eco-friendly and sustainable energy source alternative. Lithiumion batteries (LIBs) have been the most successful rechargeable battery since their commercialization. However, owing to exhaustion and instability in price of scarce raw materials, sodium-ion batteries (SIBs) have emerged as the most attractive alternative to LIBs. Nonetheless, there are still burdens to overcome for SIBs to achieve competitiveness over LIBs, particularly in improving their energy density. To address the burdens, diverse materials have been studied to date. Yet, progress and development on achieving high performance negative electrode for SIBs still remain as a key object. Hard carbon (HC) has been considered as attractive candidate, because of its high capacity and low production cost. Despite the attractiveness, inherent limitations of HCs such as excessive formation of solid-electrolyte interphase (SEI) and large irreversible capacity loss have hindered their applications. To confront this challenge, core-shell concept has been suggested by the team of Division 3.6 at BAM. The concept is to create carbon coating (shell structure) around the core material in order to mitigate formation of excessive SEI and enhance performance of the negative electrode. Shu-Han Wu and Paul Alexander Appel from Division 3.6 at BAM have synthesized various core-shell materials and have observed promising results. They made great progress in the research of core-shell materials, for example improving initial coulombic efficiency from 31% to 68%. However, there are still room for improvement. The task of this bachelor thesis work is to enhance the electrochemical performance of the core-shell materials and to investigate a more effective carbon coating method on the core material by exploring various coating parameters and different drying procedures. In this bachelor thesis, Shu-Han Wu’s synthesis precedure was repeated, ZIF-8 was pyrolyzed at 1000°C with a consequent treatment with HCl gas and washed with de� ionised water. The material (ZIF8_1000_HCl gas_H2O) was re-synthesized. Increasement in N2 Physisorption was observed after the acid treatment, consistent to Shu-Han Wu’s syntheis. The as-synthesized material was used as core material throughout this bachelor work. Moreover, 4 different core-shell carbon materials were synthesized by using chemical vapor deposition (CVD) and ball milling as synthesis methods. was used as core material and toluene was used as carbon precursor for CVD. CVD displayed an effective formation of shell structure evidenced by steep reduction in specific surface area (SSABET) from N2 physisorption characterization. Ball milling revealed to cause defects in shell structure, which was noticeable on increase in SSABET (from 14 to 379 m2 g-1) and pore size distribution characterization. Drying of powder material prior to CVD process did not exhibit a difference in porosity on the final product after CVD. From the galvanostatic cycling tests at a current density of 20 IVmA g⁻¹, it was evident that formation of shell structure enhances the performance of the material. Among the synthesized core-shell materials, the material double 1.5 h CVD with no ball milling in between exhibited the most excellent performance (ICE 60.1%). Powder drying prior to CVD showed a positive influence on improving the electrochemical performance (ICE improved from 45.1% to 51.9%). Increasing drying temperature of electrode resulted in increasements of performance, where the peak performance was reached at drying at 200°C (ICE 57.7%). The investigations of impacts of coating and drying on electrochemical properties of core-shell carbon materials would provide basis and motivation for further development of advanced negative electrode materials for SIBs. KW - Sodium-ion batteries KW - Hard carbon KW - Core-shell materials PY - 2025 SP - 1 EP - 39 CY - TU Berlin AN - OPUS4-65130 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Bioinspired Electrode Materials N2 - Porous carbon materials are known for their applicability in important areas such as sorption, catalysis and electrochemistry (e.g. fuel cell catalysts, supercapacitor or battery electrodes). It was shown that nitrogen doped carbons (NDCs) act as an inexpensive and highly active non-metal catalyst in the oxygen reduction reaction (ORR), with the potential to reach performances of practical need one day. A key strategy towards improvement for this aim comprises the generation of advantageous porosity, which typically means high surface area and mass transport pores as well as the control over the chemistry of catalytically active sites. My group developed novel sol-gel type strategies that are using molten salts or molten acids as unconventional reaction medium for the porogenesis in doped carbons, thereby revisiting classic activation techniques. Carbon materials with extra high surface area of ~2800 m2 g-1 and pore volumes, up to four times as high as in commercial activated carbons, are obtained. Hierarchical pore systems, like used in nature (leaves, lungs, etc.) facilitate some of the electrochemical performances. Moreover, because of the elements also defining organic matter, also binding motifs can be realized that are reminiscent of proteins/enzymes. We established the pyrolytic template-ion reaction using cations like Mg2+ and Zn2+ to imprint tetrapyrrolic N4 sites (like in the heme molecule), embedded into the carbon structure. The imprinted structure may be utilized as catalytically active site by performing ion-exchange reactions. This way catalytic activity can be tuned for different societal important reactions, but also the defined catalysts structure allows the assignment of structure-performance relations. Other “tricks” that nature uses, are to influence the passage of ions through cell walls, or to expel water molecules from catalytically active sites. I will show some recent work on carbon electrodes used as battery active materials that utilizes similar pathways. T2 - Kolloquium des Instituts für Anorganische und Allgemeine Chermie der Universität Freiburg CY - Freiburg, Germany DA - 04.12.2025 KW - Carbon KW - M-N-C KW - Fuel cell KW - Core-shell KW - Sodium ion battery PY - 2025 AN - OPUS4-65021 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Design, Structure and Performance of Fe-N-C Catalysts Based on Active-Site Imprinting N2 - Atomically dispersed M-N-C catalysts such as Fe-N-Cs are most promising alternatives for precious metal-based catalysts for several energy conversion reactions. Early reports on such materials date back to the 1960´s, when Jasinski pioneered the research based on tetrapyrrolic phthalocyanine macrocycles which were inspired by natural transition metal porphyrin complexes present in enzyme active sites. For decades, the selective synthesis of these catalysts was complicated by the formation of side phases due to the harsh reaction conditions facilitating side phase formation. In 2018, we introduced a mild procedure, which is conservative toward the carbon support and leads to atomically dispersed Fe-N4 site formation at temperatures as low as 80 °C in a wet-chemical step, essentially decoupling the preparation of the N-C backbone from the preparation of the active sites. The key concept therein is the so-called active-site imprinting into the N-C backbone using pyrolytic template ion reactions, allowing for high concentrations of N4 sites resulting in more than 3 at.% of Fe in atomically dispersed phase. Using the same precursor that is used for the preparation of phthalocyanines, we were able to produce atomically-dispersed single-site Fe-N-Cs that consist of tetrapyrrolic FeN4 complexes. The tetrapyrrolic Fe-N-C derivatives are highly active and extraordinary selective electrocatalysts for the oxygen reduction reaction. The well-defined and homogeneous active site structure allows to quantify the intrinsic catalytic activity of the materials in acid and base, reveal insights into the electrocatalytic mechanism and to reveal distinct degradation mechanism upon storage and electrochemical cycling. Herein, the general synthetic strategy of active-site imprinted catalysts will be discussed mainly based on both Mg-ion and Zn-ion templating towards “designed” Fe-N-C catalysts. The tetrapyrrolic active sites will be discussed regarding structure, activity, selectivity and durability. This hopefully stimulates a fruitful discussion of the perspectives in the field. T2 - Chemical Engineering Research Seminar of Higgins Group of McMaster University CY - Hamilton, Canada DA - 29.05.2025 KW - Carbon KW - M-N-C KW - Electrocatalysis KW - Fuel cells PY - 2025 AN - OPUS4-64913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krug von Nidda, Jonas T1 - Tetrapyrrolic Nitrogen Doped Carbons by Pyrolytic Template Ion Reactions as Platform for Electrocatalysis N2 - Atomically dispersed M-N-C catalysts such as Fe-N-Cs are most promising alternatives for precious metal-based catalysts for energy conversion reactions. Early reports on such materials date back to the 1960´s, when Jasinski pioneered the research based on tetrapyrrolic phthalocyanine macrocycles which were inspired by natural transition metal porphyrin complexes present in enzyme active-sites. For decades, the selective synthesis of these catalysts was complicated by the formation of side phases due to the harsh reaction conditions facilitating side phase formation. In 2018, we introduced a mild procedure, which is conservative toward the carbon support and leads to atomically dispersed Fe-N4 site formation at temperatures as low as 80 °C in a wet-chemical step, essentially decoupling the preparation of the nitrogen-doped carbon (NDC) backbone from the preparation of the active-sites. The key concept therein is the so-called active-site imprinting into the NDC backbone using pyrolytic template ion reactions, allowing for high concentrations of N4 sites resulting in more than 3 at.% of Fe in atomically dispersed phase. Using the same precursor that is used for the preparation of phthalocyanines, we were able to produce tetrapyrrolic NDCs as a materials platform to synthesize atomically-dispersed single-site Fe-N-Cs comprising tetrapyrrolic FeN4 complexes by ion-exchange reactions. The tetrapyrrolic Fe-N-C derivatives are highly active and extraordinary selective electrocatalysts for the oxygen reduction reaction in acidic. The mere tetrapyrrolic NDC are likewise highly active ORR-catalysts in alkaline. The well-defined and homogeneous active-site structure allows to quantify the intrinsic catalytic activity of the materials in acid and base, reveal insights into the electrocatalytic mechanism and to reveal distinct degradation mechanism upon storage and electrochemical cycling. Herein, the general synthetic strategy will be discussed mainly based on Zn-ion templating towards Fe-N-C catalysts. The catalytic active-sites will be discussed regarding structure and potential as fuel cell catalyst. T2 - Carbon Conference 2025 CY - Saint-Malo, France DA - 29.06.2025 KW - Electrocatalysis KW - Oxygen Reduction Reaction KW - Noble Metal Free KW - Nitrogen Doped Carbon PY - 2025 AN - OPUS4-64968 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wu, Shu-Han T1 - Sodium Storage Mechanisms and Performance Improvement of Synthetic Hard Carbon Materials N2 - Hard carbons (HCs) are promising anodes for sodium-ion batteries (SIBs) due to their high capacity and low cost. However, their broader use is limited by an incomplete understanding of sodium storage mechanisms. Internal porosity is key to high capacity, but tuning its chemical functionality remains challenging. In this study, we designed core–shell carbon materials featuring closed pores and tailored surface chemistry to distinguish reversible sodium storage from irreversible capacity losses associated with solid electrolyte interphase (SEI) formation. Our results reveal that external porosity can be clearly converted into internal porosity, leading to enhanced sodium storage performance, with capacities exceeding those of lithium in graphite. T2 - Advanced Automotive Battery Conference (AABC) 2025 CY - Mainz, Germany DA - 23.06.2025 KW - Sodium-ion batteries KW - Hard carbon KW - Core-shell materials PY - 2025 AN - OPUS4-65133 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Appel, Paul Alexander T1 - Linking Porosity to Storage Capacity: Core-Shell Carbon Materials as High-Capacity Anodes for Sodium Ion Batteries N2 - Hard carbons (HCs) are currently one of the most promising anode materials for sodium-ion batteries (SIBs). However, the Na storage mechanism remains controversial, leaving the theoretical limits of carbon anodes unclear. To deconvolute the specific capacity from irreversible capacity losses, resulting from the formation of solid electrolyte interphase (SEI), core-shell carbon materials were synthesized. Based on these core-shell materials, an investigation of the storage mechanism of sodium is possible. T2 - Advanced Battery Power 2025 CY - Aachen, Germany DA - 01.04.2025 KW - Electrochemical Energy Materials KW - Negative Electrodes KW - Sodium Ion Batteries PY - 2025 AN - OPUS4-65114 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Appel, Paul Alexander T1 - Developing Tailor-Made Core-Shell Carbon Negative Electrode Materials for Sodium Ion Batteries N2 - Hard carbons (HCs) are currently one of the most promising anode materials for sodium-ion batteries (SIBs). However, the Na storage mechanism remains controversial, leaving the theoretical limits of carbon anodes unclear. To deconvolute the specific capacity from irreversible capacity losses, resulting from the formation of solid electrolyte interphase (SEI), core-shell carbon materials were synthesized. Based on these core-shell materials, an investigation of the storage mechanism of sodium is possible. T2 - Sodium Battery Symposium CY - Dresden, Germany DA - 03.09.2025 KW - Electrochemical Energy Materials KW - Negative Electrodes KW - Sodium Ion Batteries PY - 2025 AN - OPUS4-65116 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krug von Nidda, Jonas T1 - Porous „Ionophoric“ Carbon Materials: Synthesis Routes and Electrochemical Applications N2 - Porosity tuning and “doping” with heteroatoms and/or transition metals are key strategies to improve the performance of porous carbons. Nitrogen doped carbons (NDCs) with macrocyclic functionalities and the respective M-coordinated NDCs (M-N-Cs) containing FeN4 sites, are very promising electrodes for Na-storage and electrocatalytic conversions. Their functional groups are reminiscent of those in biomolecules like e.g. hemoglobin. The materials can carry ions and can be regarded as “ionophoric” carbons. T2 - AKK-Herbsttagung 2025 CY - Mainz, Germany DA - 22.09.2025 KW - Electrocatalysis KW - Energy Storage KW - Noble Metal Free KW - Nitrogen Doped Carbon PY - 2025 AN - OPUS4-64969 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dietzmann, Simon T1 - X-ray Absorption Spectroscopy to Uncover the Structure of Metal and Nitrogen Doped Carbon Electrocatalysts N2 - High-performance electrocatalysts and sodium-ion (Na+) storage materials for Na-ion batteries are essential for efficient energy conversion and storage. Metal and nitrogen enriched carbons (M–N–Cs) are promising candidates due to their intrinsic conductivity and tunable properties through targeted modification. To understand and optimize the catalytically active sites at the pseudo-molecular level, detailed structural characterization is crucial. T2 - Bessy User Meeting CY - Berlin, Germany DA - 03.12.2025 KW - Elechtrochemistry KW - XAS KW - Single atom catalysts PY - 2025 AN - OPUS4-65010 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Anna T1 - Tayloring Accessible Surfaces of Activated Carbons via Mechanochemical Processing N2 - Controlling the external accessibility of porous carbons without compromising their internal microporous network is essential for material functionality. Hard Carbons (HC) were ball milled in the presence of aromatic compounds, forming a disordered surface barrier that partially blocks pore entrances. This selectively reduces their external specific surface area (SSA) while preserving internal storage capacity. T2 - Income 2025 CY - Berlin, Germany DA - 14.09.2025 KW - Ball Milling KW - Sealed Porosity KW - Mechanochemistry PY - 2025 AN - OPUS4-65117 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Deciphering Structure-Performance Relations of PGM-Free Fe-N-C Electrocatalysts Based on Synthetic Materials Design N2 - Fe-N-C electrocatalysts are very promising alternatives for precious metal-based catalysts for energy conversion reactions.[1-3] Early reports on such materials date back to the 1960´s, when Jasinski pioneered the research based on tetrapyrrolic phthalocyanine macrocycles which were inspired by natural transition metal porphyrin complexes present in enzyme active sites.[3] For decades, the synthesis of these catalysts with a high iron loading was complicated by the formation of side phases due to the harsh reaction conditions facilitating side phase formation. In 2018, we introduced a mild procedure, which is conservative toward the carbon support and leads to active-site formation at low temperatures in a wet-chemical step, essentially decoupling the preparation of the N-C backbone from the preparation of the active sites.[4, 5] The key concept therein is the so-called active-site imprinting into the N-C backbone using pyrolytic template ion reactions.[4][5] Using the same precursor that is used for the preparation of phthalocyanines, we were able not only to produce atomically-dispersed single-phase Fe-N-Cs with a high iron loading, but were also able to selectively form tetrapyrrolic Fe-N4 complexes.[6] The tetrapyrrolic Fe-N-C derivatives are highly active and extraordinary selective electrocatalysts for the oxygen reduction reaction. Deconvolution of morphological effects on the performance allowed to quantify the intrinsic catalytic activity of the materials in acidic and alkaline conditions and gives new insights into the reaction mechanism in alkaline.[7, 8] A distinct degradation mechanism upon storage was found for the tetrapyrrolic sites and new insights on degradation upon fuel cell operation could be obtained.[9, 10] Herein, the general synthetic material design strategy for atomically dispersed catalysts will be discussed based on tetrapyrrolic Fe-N-C catalysts, which will be analyzed for their potential as PGM-free fuel cell catalysts. T2 - Research Seminar of National Institute of Chemical Physics and Biophysics CY - Tallinn, Estonia DA - 29.09.2025 KW - Carbon KW - M-N-C KW - Electrocatalysis KW - Fuel cells PY - 2025 AN - OPUS4-64916 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Low, Jian Liang T1 - Active Site Determination in Pyrolyzed M-N-C Electrocatalysts by Gas-sorption N2 - Metal and nitrogen-doped carbons (M-N-Cs) with M-N4 moieties as the generally accepted active sites, have gradually reached promising levels of activity towards crucial electrochemical reactions like the oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO2RR). Even the metal-free counterparts, the nitrogen-doped carbons (NDCs), are common and well-studied electrocatalysts for ORR in alkaline media. In these disordered porous materials, the characterization and quantification of (M)N4 sites can be challenging and time-consuming, with many spectroscopic methods drastically overestimating their site accessibility for catalytic applications. In this study, we explore an alternative approach towards active site characterization and quantification in M-N-Cs based on multi-Langmuir analysis of CO2-sorption isotherms at low pressures, with support fromelectronic DFT calculations. T2 - Electrolyser and Fuel Cell Forum 2025 CY - Lucerne, Switzerland DA - 01.07.2025 KW - Metal- and Nitrogen Doped Carbon (M-N-C) KW - Active Site Characterization KW - Gas sorption KW - Active-Site Imprinting PY - 2025 AN - OPUS4-65147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Negative Electrode Ionophoric Core-Shell Carbon for Sodium-Ion Batteries N2 - The current strong interest in electromotive mobility and the need to transition to an energy grid with sustainable storage devices has led to a renewed interest in sodium ion batteries (SIBs). Amorphous disordered carbons such as hard carbons (HCs) are promising candidates for high-capacity negative electrode materials in SIBs. Their high capacities, however, are often accompanied with high irreversible capacity losses during the initial cycles,[1] while low initial losses are accompanied with moderate capacities.[2] In our research we are aiming morphologically and chemically functional carbons. Morphologically, our target is a local separation of reversible sodium storage and irreversible losses in novel synthetic carbon anodes, using a core-shell concept. On chemical side, we aim at ion-binding functional groups. We investigated different methods to obtain core-shell structures to restrict SEI formation to the external particle surface, while leveraging the Na storage potential of porous carbon core materials. Moreover, we apply active-site imprinting to realise disting ion-binding features into the core carbons. The electrochemical performance of those materials can be rather easily altered upon removing/exchanging the ions bound to the functional group. Herein, we will focus on the synthesis of zeolitic imidazolate framework (ZIF) based NDCs. Different analytical methods, e.g., physisorption (N2, Ar, CO2), XPS, XAS, and NMR, will be used to understand the alteration of morphological and chemical features upon ion exchange. T2 - Mat-Sus Spring Meeting 2024 CY - Barcelona, Spain DA - 04.03.2024 KW - Ionophoric carbon PY - 2024 AN - OPUS4-61938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Design Structure and Performance of FeNC Catalysts N2 - Atomically dispersed M-N-C catalysts such as Fe-N-Cs are most promising alternatives for precious metal-based catalysts for energy conversion reactions.[1-3] Early reports on such materials date back to the 1960´s, when Jasinski pioneered the research based on tetrapyrrolic phthalocyanine macrocycles which were inspired by natural transition metal porphyrin complexes present in enzyme active sites.[3] For decades, the selective synthesis of these catalysts was complicated by the formation of side phases due to the harsh reaction conditions facilitating side phase formation. In 2018, we introduced a mild procedure, which is conservative toward the carbon support and leads to atomically dispersed Fe-N4 site formation at temperatures as low as 80 °C in a wet-chemical step, essentially decoupling the preparation of the N-C backbone from the preparation of the active sites.[4, 5] The key concept therein is the so-called active-site imprinting into the N-C backbone using pyrolytic template ion reactions, allowing for high concentrations of N4 sites resulting in more than 3 at.% of Fe in atomically dispersed phase.[4-6] Using the same precursor that is used for the preparation of phthalocyanines, we were able to produce atomically-dispersed single-site Fe-N-Cs that consist of tetrapyrrolic FeN4 complexes.[6] The tetrapyrrolic Fe-N-C derivatives are highly active and extraordinary selective electrocatalysts for the oxygen reduction reaction. The well-defined and homogeneous active site structure allows to quantify the intrinsic catalytic activity of the materials in acid and base,[7, 8] reveal insights into the electrocatalytic mechanism and to reveal distinct degradation mechanism upon storage and electrochemical cycling.[9, 10] Herein, the general synthetic strategy of active-site imprinted catalysts will be discussed mainly based on Zn-ion templating towards tetrapyrrolic Fe-N-C catalysts. The catalytic active sites will be discussed regarding structure, activity, selectivity and durability, hence the potential as fuel cell catalyst. T2 - ECS Spring Meeting 2025 CY - Montreal, Canada DA - 18.05.2025 KW - Fuel Cell KW - ELectrocatalyst KW - Fe-N-C KW - Carbon PY - 2025 AN - OPUS4-64910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cerny, Alain T1 - Engineering Activated Carbon via Chemical Vapor Deposition for High-Performance Core-Shell Carbon Anodes in Sodium-Ion Batteries N2 - Rising demand for sustainable energy storage has renewed interest in sodium-ion batteries (SIBs) as alternative to lithium-ion batteries. Although hard carbon and related materials are common SIB-anodes, the correlation between its structure and ion storage mechanism remains unclear.[1] As shown recently, the pore design is essential to block the formation of excessive solid electrolyte interphase (SEI) and allows the formation of pseudo-metallic clusters inside the pores.[2,3] Adjusting the diameter of the pore entrance, enables a reversible low-potential plateau (< 0.1 V), which significantly enhances the capacity (potentially up to 450-500 mAh/g) compared to graphite (Qtheo = 372 mAh/g) in Li-ion batteries.[2] Activated carbon (AC) is a low-cost material with abundant micropores and high surface area, making it a promising anode candidate for SIBs. However, its performance is often hindered by structural disorder and excessive SEI-formation. Hence, mitigating active-species loss is essential to achieve high specific capacities (> 300 mAh g-1).[3] The aim herein was to investigate the relationship between the properties of the AC and the CVD-conditions required to achieve an efficient SIB-anode. This study introduces an optimized chemical vapor deposition (CVD) method to modify various, highly porous commercial ACs aiming towards core-shell carbons, consisting of a porous core and a non-graphitic CVD-shell.[3] The ACs were treated via CVD and characterized using a range of techniques including gas physisorption, small-angle x-ray scattering and X-ray diffraction. The electrochemical properties of the different materials, prior and after CVD-coating, were analysed in half cells vs. Na-metal. After coating, gas physisorption confirmed a significantly lower surface area for the materials. Depending on the porosity of the material, a longer CVD-time was necessary to fully coat the particles. The successful formation of core-shell carbons enables separation of the storage mechanism from SEI-formation. The CVD-process enables precise control over the microstructure of the carbon material, allowing to enhance the reversible Na-storage capacity, e.g., from 107 mAh g-1 to 353 mAh g-1 while significantly reducing initial Coulombic losses by 73%. The greatly increased low-potential capacity verifies the formation of an electrolyte-tight CVD shell enabling Na-storage in the porosity of the core. The established link between porosity, CVD-parameters, and performance guides optimization for future materials. T2 - Batterieforum 2026 CY - Berlin, Germany DA - 20.01.2026 KW - Sodium-Ion Battery KW - Carbon KW - Chemical Vapour Deposition PY - 2026 AN - OPUS4-65510 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wu, Shu-Han T1 - Revealing the Impact of Nitrogen Sites on the Sodium Storage Mechanism in Carbon Electrodes N2 - Unlike lithium-ion batteries (LIBs), where crystalline graphite is commonly used as the negative electrode material, disordered carbons are regarded as more promising for sodium-ion batteries (SIBs). However, further advances towards better reversibility and higher specific capacity are still needed to match or even exceed the properties of graphite in LIBs. The main challenge is the complex and unpredictable Na-storage mechanism in disordered carbons. Recently, Matsukawa et al. have reported that the reversibility of (de)sodiation processes of ultra microporous carbons is higher compared to carbon materials with larger pore sizes.[2] Ultra micropores are accessible only to Na+-ions and not to solvent molecules. Therefore, ultra micropores can be used for Na-storage, however, do not significantly contribute to side reactions caused by solid-electrolyte interphase (SEI) formation, which reduces the related irreversible capacity loss. Building on this concept, the origins of specific capacity and irreversible losses were further explored in the current work by modifying the chemical composition of zeolitic imidazolate framework (ZIF-8) derived carbons, while maintaining comparable porosity. This involved adjusting the nitrogen content as well as the types of nitrogen sites through temperature variation. Subsequently, these ZIF-8 derived carbons were modified with a protective ion-sieving carbon shell formed by chemical vapor deposition (CVD). This synthesis methodology enables effective distinction between reversible Na-storage and irreversible processes, e.g., SEI-formation. The former and later are mainly dictated by the properties of the ZIF-derived carbon core and the CVD based shell, respectively. The structure and morphology of the materials were characterized by electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. In addition, different gas sorption techniques were carried out to analyze the porosity, pore sizes and specific surface areas. The electrochemical performance of the prepared materials was evaluated in coin cells vs. Na-metal. The results of the tailor-made core-shell carbons reveal that a higher nitrogen content leads to a greater capacity in the sloping region, but to a lower capacity in the plateau region of the voltage profile. In addition, the overall capacity is higher for materials with lower nitrogen content. Lastly, it is important to highlight that the incorporation of ion-sieving carbon shell results in a significant overall increase in capacity compared to materials without a carbon shell. The highest reversible capacities (i.e., 381 +/- 4 mAh g–1) were obtained for the core-shell carbon comprising a ZIF-derived core pyrolyzed at 1000°C. Apparently, the N-sites in the as-synthesized materials facilitate the adsorption of Na+ ions, indicating that Na+ ions preferentially adhere to these active sites during the sodiation process. It is worth noting that these results were observed while minimizing side reactions, making them more reliable and providing conclusive evidence for the long-debated Na-storage mechanism. Moreover, the lower capacity observed in materials with higher nitrogen content may be attributed to a lower electrical conductivity. T2 - Advanced Battery Power Conference 2025 CY - Aachen, Germany DA - 02.04.2025 KW - Sodium-ion batteries KW - Hard carbon KW - Core-shell materials PY - 2025 AN - OPUS4-65132 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Menga, Davide A1 - Li, Yan‐Sheng A1 - Damjanović, Ana Marija A1 - Proux, Olivier A1 - Wagner, Friedrich E. A1 - Fellinger, Tim-Patrick A1 - Gasteiger, Hubert A. A1 - Piana, Michele T1 - On the Stability of an Atomically‐Dispersed Fe−N−C ORR Catalyst: An In Situ XAS Study in a PEMFC N2 - The stability of Fe−N−C oxygen reduction reaction (ORR) electrocatalysts has been considered a primary challenge for their practical application in proton exchange membrane fuel cells (PEMFCs). While several studies have attempted to reveal the possible degradation mechanism of Fe−N−C ORR catalysts, there are few research results reporting on their stability as well as the possible Fe species formed under different voltages in real PEMFC operation. In this work, we employ in‐situ X‐ray absorption near‐edge structure (XANES) to monitor the active‐site degradation byproducts of an atomically dispersed Fe−N−C ORR catalyst under a H2/O2‐operating PEMFC at 90 % relative humidity and 80 °C. For this, stability tests were carried out at two constant cell voltages, namely 0.4 and at 0.8 V. Even though the ORR activity of the Fe−N−C catalyst decreased significantly and was almost identical at the end of the tests for the two voltages employed, the analysis of the XANES recorded under H2/N2 configuration at 0.6 and 0.9 V within the stability test suggests that two different degradation mechanisms occur. They are demetalation of iron cations followed by their precipitation into Fe oxides upon operation at 0.8 V, versus a chemical carbon oxidation close to the active sites, likely triggered by reactive oxygen species (ROS) originated from the H2O2 formation, during the operation at 0.4 V. KW - PGM-free catalysts PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638981 DO - https://doi.org/10.1002/celc.202400228 SN - 2196-0216 VL - 11 IS - 18 SP - 1 EP - 16 PB - Wiley VHC-Verlag AN - OPUS4-63898 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Menga, D. A1 - Low, Jian Liang A1 - de Oliveira Guilherme Buzanich, Ana A1 - Paulus, B. A1 - Fellinger, Tim-Patrick T1 - The Tetrapyrollic Motif in Nitrogen Doped Carbons and M-N-C Electrocatalysts as Active Site in the Outer-Sphere Mechanism of the Alkaline Oxygen Reduction Reaction N2 - Development and fundamental understanding of precious-group-metal-free electrocatalysts is hampered by limitations in the quantification of the intrinsic activity of different catalytic sites and understanding the different reaction mechanisms. Comparing isomorphic nitrogen-doped carbons, Zn-N-Cs and Fe-N-Cs with the common tetrapyrrolic motif, a catalyst-independent outer-sphere rate-determining step in the alkaline oxygen reduction reaction is observed. Density functional theory (DFT) simulations on tetrapyrrolic model structures indicate the highest occupied molecular orbital (HOMO) level as a good descriptor for the catalytic activity. Contour plots suggest that the electron transfer occurs directly from the tetrapyrrolic coordination site, rather than from the metal center. Metal-free tetrapyrrolic N4 sites are discovered to be highly active oxygen reduction reaction (ORR) active sites in alkaline that reach turnover frequencies (TOF) of 0.33 and 1.84 s−1 at 0.80 and 0.75 VRHE in the order of magnitude of tetrapyrrolic Fe–N4 sites in the acidic ORR. While Zn-coordination lowers the HOMO level and therefore the catalytic activity, Fe-coordination lifts the HOMO level resulting in TOF values of 0.4 and 4 s−1 for tetrapyrrolic Fe–N4 sites at 0.90 and 0.85 VRHE, respectively. At higher mass activities, the peroxide reduction becomes rate-limiting, where highest peroxide production rates are observed for the nitrogen-doped carbon. KW - Tetrapyrollic KW - Motif KW - Nitrogen KW - Carbons KW - Alkaline Oxygen PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-606239 DO - https://doi.org/https://doi.org/10.1002/aenm.202400482 SN - 1614-6832 VL - 2024 SP - 1 EP - 8 PB - Wiley-VCH AN - OPUS4-60623 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwarz, I. A1 - Rieck, Arielle A1 - Mehmood, Asad A1 - Bublitz, R. A1 - Bongers, L. A1 - Weuster-Botz, D. A1 - Fellinger, Tim-Patrick T1 - PEM Electrolysis in a Stirred-Tank Bioreactor Enables Autotrophic Growth of Clostridium ragsdalei with CO2 and Electrons N2 - Acetogenic bacteria produce CO2-based chemicals in aqueous media by hydrogenotrophic conversion of CO2, but CO is the preferred carbon and electron source. Consequently, coupling CO2 electrolysis with bacterial fermentation within an integrated bio-electrocatalytical system (BES) is promising, if CO2 reduction catalysts are available for the generation of CO in the complex biotic electrolyte. A standard stirred-tank bioreactor was coupled to a zero-gap PEM electrolysis cell for CO2 conversion, allowing voltage control and separation of the anode in one single cell. The cathodic CO2 reduction and the competing hydrogen evolution enabled in-situ feeding of C. ragsdalei with CO and H2. Proof-of-concept was demonstrated in first batch processes with continuous CO2 gassing, as autotrophic growth and acetate formation was observed in the stirred BES in a voltage range of −2.4 to −3.0 V. The setup is suitable also for other bioelectrocatalytic reactions. Increased currents and lower overvoltages are however required. Atomically-dispersed M−N−C catalysts show promise, if degradation throughout autoclaving can be omitted. The development of selective and autoclavable catalysts resistant to contamination and electrode design for the complex electrolyte will enable efficient bioelectrocatalytic power-to-X systems based on the introduced BES. KW - Energy Conversion PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594766 DO - https://doi.org/10.1002/celc.202300344 SN - 2196-0216 SP - 1 EP - 10 PB - Wiley VHC-Verlag AN - OPUS4-59476 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwarz, I. A1 - Rieck, Arielle A1 - Mehmood, Asad A1 - Bublitz, R. A1 - Bongers, L. A1 - Weuster-Botz, D. A1 - Fellinger, Tim-Patrick T1 - PEM Electrolysis in a Stirred-Tank Bioreactor Enables Autotrophic Growth of Clostridium ragsdalei with CO2 and Electrons N2 - Acetogenic bacteria produce CO2-based chemicals in aqueous media by hydrogenotrophic conversion of CO2, but CO is the preferred carbon and electron source. Consequently, coupling CO2 electrolysis with bacterial fermentation within an integrated bio-electrocatalytical system (BES) is promising, if CO2 reduction catalysts are available for the generation of CO in the complex biotic electrolyte. A standard stirred-tank bioreactor was coupled to a zero-gap PEM electrolysis cell for CO2 conversion, allowing voltage control and separation of the anode in one single cell. The cathodic CO2 reduction and the competing hydrogen evolution enabled in-situ feeding of C. ragsdalei with CO and H2. Proof-of-concept was demonstrated in first batch processes with continuous CO2 gassing, as autotrophic growth and acetate formation was observed in the stirred BES in a voltage range of 􀀀 2.4 to 􀀀 3.0 V. The setup is suitable also for other bioelectrocatalytic reactions. Increased currents and lower overvoltages are however requ KW - PEM KW - Stirred-Tank Bioreactor KW - Clostridium ragsdalei PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615239 UR - http://www.chemelectrochem.org/ DO - https://doi.org/10.1002/celc.202300344 VL - 11 IS - 6 SP - 1 EP - 9 PB - Chemistry Europe and Wiley-VCH GmbH AN - OPUS4-61523 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Menga, D. A1 - Wagner, F. E. A1 - Fellinger, Tim-Patrick T1 - Life cycle of single atom catalysts: a Mo¨ssbauer study on degradation and reactivation of tetrapyrrolic Fe–N–C powders N2 - The degradation of a single-site atomically dispersed, model Fe–N–C powder catalyst with high activity is investigated using cryo-Mössbauer spectroscopy. The results indicate a degradation initiated by an Fe2+ to Fe3+ oxidation due to coordination of oxygen to tetrapyrrolic Fe–N4 sites at atmospheric conditions (change between characteristic doublets) before iron(III) oxide is formed (sextet). Thermal reactivation can be used to restore substantial catalytic activity of aged Fe–N–C powders. KW - Life cycle KW - Atom catalysts KW - Tetrapyrrolic Fe–N–C powders PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586007 DO - https://doi.org/10.1039/d3mh00308f SN - 2051-6347 SP - 1 EP - 7 PB - Royal Society of Chemistry (RSC) AN - OPUS4-58600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Menga, D. A1 - Wagner, F. E. A1 - Fellinger, Tim-Patrick T1 - Life cycle of single atom catalysts: a Mössbauer study on degradation and reactivation of tetrapyrrolic Fe–N–C powders N2 - The degradation of a single-site atomically dispersed, model Fe–N–C powder catalyst with high activity is investigated using cryo-Mössbauer spectroscopy. The results indicate a degradation initiated by an Fe2+ to Fe3+ oxidation due to coordination of oxygen to tetrapyrrolic Fe–N4 sites at atmospheric conditions (change between characteristic doublets) before iron(III) oxide is formed (sextet). Thermal reactivation can be used to restore substantial catalytic activity of aged Fe–N–C powders. KW - Single atom catalysts KW - Mössbauer study KW - Tetrapyrrolic Fe–N–C powders PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-589352 DO - https://doi.org/10.1039/d3mh00308f VL - 10 SP - 5577 EP - 5583 PB - Royal Society of Chemistry AN - OPUS4-58935 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn A1 - Fellinger, Tim-Patrick T1 - Berlin Battery Lab - Vom Material zur Zelle - Batterieinnovation aus Berlin N2 - Das Berlin Battery Lab (BBL) vereint exzellente Materialforschung, modernste Analytik und gezielten Technologietransfer. Als gemeinsames Labor von BAM, HZB und der Humboldt Universität zu Berlin entwickeln wir zukunftsfähige Natrium-Ionen- und Metall-Schwefel-Batterien – von der Materialidee bis zur funktionsfähigen Zelle. T2 - Batteriaforum Deutschland CY - Berlin, Germany DA - 20.01.2026 KW - Batterie KW - Kooperation KW - Natrium-Ionen KW - BBL PY - 2026 AN - OPUS4-65410 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bates, J. S. A1 - Martinez, J. J. A1 - Hall, M. N. A1 - Al-Omari, A. A. A1 - Murphy, E. A1 - Zeng, Y. A1 - Luo, F. A1 - Primbs, M. A1 - Menga, D. A1 - Bibent, N. A1 - Sougrati, M. T. A1 - Wagner, F. E. A1 - Atanassov, P. A1 - Wu, G. A1 - Strasser, P. A1 - Fellinger, Tim-Patrick A1 - Jaouen, F. A1 - Root, T. W. A1 - Stahl, S. S. T1 - Chemical Kinetic Method for Active-Site Quantification in Fe-N‑C Catalysts and Correlation with Molecular Probe and Spectroscopic Site-Counting Methods N2 - Mononuclear Fe ions ligated by nitrogen (FeNx) dispersed on nitrogen-doped carbon (Fe-N-C) serve as active centers for electrocatalytic O2 reduction and thermocatalytic aerobic oxidations. Despite their promise as replacements for precious metals in a variety of practical applications, such as fuel cells, the discovery of new Fe-N-C catalysts has relied primarily on empirical approaches. In this context, the development of quantitative structure−reactivity relationships and benchmarking of catalysts prepared by different synthetic routes and by different laboratories would be facilitated by the broader adoption of methods to quantify atomically dispersed FeNx active centers. In this study, we develop a kinetic probe reaction method that uses the aerobic oxidation of a model hydroquinone substrate to quantify the density of FeNx centers in Fe-N-C catalysts. The kinetic method is compared with low-temperature Mössbauer spectroscopy, CO pulse chemisorption, and electrochemical reductive stripping of NO derived from NO2 − on a suite of Fe-N-C catalysts prepared by diverse routes and featuring either the exclusive presence of Fe as FeNx sites or the coexistence of aggregated Fe species in addition to FeNx. The FeNx site densities derived from the kinetic method correlate well with those obtained from CO pulse chemisorption and Mössbauer spectroscopy. The broad survey of Fe-N-C materials also reveals the presence of outliers and challenges associated with each site quantification approach. The kinetic method developed here does not require pretreatments that may alter active-site distributions or specialized equipment beyond reaction vessels and standard analytical instrumentation. KW - Active-Site Quantification PY - 2023 DO - https://doi.org/10.1021/jacs.3c08790 SP - 1 EP - 16 PB - ACS Publications AN - OPUS4-58889 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krug von Nidda, Jonas A1 - Fellinger, Tim-Patrick T1 - Current State of Research of Environmentally Friendly, Alternative Materials - Sodium-Ion-Batteries as an Example N2 - In order meet the anticipated future need for battery-based energy storage, it is essential to explore alternative systems beyond lithium-ion batteries. Sodium-ion batteries emerge as a promising option due to the abundance of readily available materials and the potential for reduced costs. T2 - 32. Sitzung Beraterkreis Technologie (BKT) CY - Cologne, Germany DA - 19.10.2023 KW - Sodium-ion-batteries PY - 2023 AN - OPUS4-58886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mehmood, Asad A1 - Fellinger, Tim-Patrick T1 - Ionothermal Template Transformation as a Sustainable Route Towards Carbon Electrodes in Energy Storage and Conversion N2 - Porous carbons with tuneable functionalities and morphologies have extensively been employed as electrode materials in a variety of electrochemical energy conversion and storage systems for instance in fuel cells and electrolysers as active catalysts and catalyst supports, and in secondary batteries as anode materials. Amorphous carbons with well-developed pore structures are of particular interest due to their superior mass-transport characteristics and remarkable charge storage capacities. T2 - Nano-Pak 2023, 2nd International Conference on Emerging Trends & Innovations in Nanotechnology CY - Lahore, Pakistan DA - 17.06.2023 KW - Ionothermal Template Transformation KW - Sustainable Route KW - Carbon Electrodes PY - 2023 AN - OPUS4-58897 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Metal chloride activation revisited: a sol-gel process to functional carbons N2 - Porous carbon materials are known for their applicability in important areas such as sorption, catalysis and electrochemistry (e.g. fuel cell catalysts, supercapacitor or battery electrodes). It was shown that nitrogen doped carbons (NDCs) act as an inexpensive and highly active non-metal catalyst in the oxygen reduction reaction (ORR), with the potential to reach performances of practical need one day. A key strategy towards improvement for this aim comprises the generation of advantageous porosity, which typically means high surface area and mass transport pores as well as the control over the chemistry of catalytically active sites. My group is developing novel sol-gel type strategies that are using molten salts or molten acids as unconventional reaction medium for the porogenesis in doped carbons, thereby revisiting classic activation techniques.[1,2] Carbon materials with extra high surface area of ~2800 m2 g-1 and pore volumes, up to four times as high as in commercial activated carbons, are obtained.[3] It turns out that the meso- and macrostructure is generated by means of phase separation rather than leaching reactions. However, chemical reactions between the carbon precursor and the melt are also involved. The salt cations Mg2+ and Zn2+ act as template ions, which results in metal coordination sites, embedded into the carbon structure.[4,5] The imprinted structure may be utilized as catalytically active site by performing ion-exchange reactions. The novel preparation strategy towards highly active electrocatalysts will be presented for Mg and Zn and further discussed for lighter elements. T2 - Carbon Chemistry and Materials Conference 2022 CY - Rome, Italy DA - 10.10.2024 KW - Activated carbon KW - Salt templating PY - 2022 AN - OPUS4-61936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Structure-Performance Relations of PGM-free Electrocatalysts for PEM Fuel Cells N2 - Proton-exchange membrane fuel cells are amongst the most promising energy conversion technologies today. Herein non-precious iron-coordinated nitrogen doped carbons (Fe-N-Cs) as well as metal-free nitrogen-doped carbons (NDCs) are very promising alternatives for Pt-based cathode catalysts. The early reports on the application of such materials date back to the 1960´s when Jasinski demonstrated that - similar to natural porphyrins - N-coordinated transition metal complexes can be active sites for the ORR.1 The preparation of Fe-N-Cs was strongly optimized over the years; still they typically remain with harsh reaction conditions that complicate the selective formation of active FeN4 sites. Until recently, the employment of pyrolytic temperatures was a dogma for the synthesis of FeN4 sites, however coming with unfavorable side reactions. To avoid those harmful side reaction a limit of maximum ≈3 wt.% of Fe (depending on the precursor) was reached, which was also limiting the progress in catalyst performance for this class of materials.2, 3 Since 2006 it was shown that nitrogen doped carbons (NDCs) act as an inexpensive and highly active non-metal catalyst in the oxygen reduction reaction (ORR).4 Both, NDCs and Fe-N-Cs nowadays show the potential to reach performances of practical need, where NDC seem to be promising only for alkaline conditions, while Fe-N-Cs show promise independent of the pH.5, 6 For both PGM-free catalysts, high performance requires advantageous porosity, which typically means high surface area and mass transport pores as well as the control over the chemistry of catalytically active sites. Results and Discussion My group is developing novel synthetic strategies e.g. using molten salts or molten acids as unconventional reaction medium for the preparation of carbons materials.7, 8 Carbon materials with tunable very high surface area of ~2800 m2 g-1 and pore volumes, up to four times as high as in commercial activated carbons, are obtained. Fig. 1: Scheme of the porogenesis mechanism for NDCs by phase separation in of molten salt carbonization (a) to obtain tunable high surface area and porous carbon materials with varying nitrogen content (b). It turned out that such NDCs synthesized in presence of Mg2+ or Zn2+ give rise to a high degree of pyridinic and pyrrolic sites and outstanding ORR activity in alkaline conditions. The salt cations Mg2+ or Zn2+ act as template ions, which results in tetrapyrrolic functional groups embedded into the carbon structure. Based on this, we recently introduced a mild procedure to synthesize Fe-N-C, which leads to active-site formation at low temperatures due to coordination of Fe ions to the tetrapyrrolic functional groups of NDCs.2, 3 Figure 2: Scheme of the Active-Site Imprinting Strategy. A pyrolytic template-ion reaction forms a tetrapyrrolic functional group within the carbon framework (first step). Exchange of the template ion T (with T=Mg2+ or Zn2+) with Fe results in tetrapyrrolic Fe-N-C. The synthesis strategy of active-site imprinting and transmetalation is decoupling the preparation of NDCs from the preparation of the active sites and therefore breaks with the dogma of Fe-N-Cs preparation, circumventing the limitation to 3 wt.% of Fe.9 After a thermal activation step the Fe-N-Cs derived from active site imprinting show very good performance of ORR in acidic conditions, both on the half-cell (rotating disc electrode) and full-cell (5cm2 PEM single cell) level. Figure 3: a) Rotating disk electrode measurements show the large increase in ORR activity and low amount of peroxide formed by exchange of Zn to Fe coordinated to tetrapyrrolic NDC, especially when followed by a second heat treatment. b) Single cell PEMFC H2-O2 tests show a peak power density above 0.4 W cm-2 at a catalyst loading of 2 mg cm-2. Active-site imprinting is currently used by many groups worldwide, successfully pushing the performance of Fe-N-Cs forward, with higher Fe loadings and improved porosities.10-12 Challenges are the moderate turnover frequency (0.24 e- s-1 at 0.8 VRHE) of tetrapyrrolic Fe-N4 sites, 13 and a moderate shelf-life of tetrapyrrolic Fe-N-Cs in atmospheric conditions.14 Besides improvements of electrode engineering and optimization of fuel cell management, an improved synthetic control, leading to more active and stable catalytic environments are needed to tackle the need of sustainable electrocatalysts for future energy conversion technology.15 T2 - International Conference on Materials and Systems for Sustainability (ICMaSS2023) CY - Nagoya, Japan DA - 01.12.2023 KW - PGM-free catalysts PY - 2023 AN - OPUS4-61937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - On the structure of doped carbon electrodes N2 - Carbon-based materials are promising electrodes for energy applications. Herein an overview of morphological and chemical features of such carbon materials is given. It is further shown how morphological and chemical features must be devonvoluted to be able to elucidate structure-performance realtionships that are critical to the improvement of the materials for applications such as batteries or fuel cells. T2 - TEC Summer Seminar 2022 CY - Monte Isola, Italy DA - 06.09.2022 KW - Carbon KW - M-N-C KW - Electrocatalysis KW - Energy storage PY - 2022 AN - OPUS4-61935 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krug von Nidda, Jonas T1 - Core-Shell Materials as Advanced Anodes for Sodium Ion Batteries N2 - The current imperative to shift towards an energy grid equipped with sustainable energy storage solutions has caused a renewed interest in sodium-ion batteries (SIBs). Hard carbons (HCs) are a promising option high-capacity anode materials in SIBs. Nevertheless, their elevated capacities frequently come at the cost of experiencing substantial non-reversible initial capacity losses. Commonly, significant losses are associated with irreversible reactions, such as the creation of the solid electrolyte interphase (SEI), that occur during the initial sodium insertion in HC-materials. Intriguingly, high values of irreversible capacity are often found for samples with experimentally determined low specific surface area.[1] A more comprehensive understanding of the structure-property relations is essential for quantifying and grasping the potential of hard carbon materials in sodium-ion batteries (SIBs). Thus, the objective is to employ analytical methods to establish a link between the structure and the electrochemical attributes of HC materials. This has been a challenge, partly due to the non-stoichiometric nature of the sodium storage mechanism and the disordered structure of HCs. To address the challenges mentioned above, our approach is to explore whether a core-shell structure can separate sodium storage and SEI-formation. This way, we can investigate and fine-tune storage capacity and irreversible losses, independently. The strategy involves the synthesis of various porous carbon structures to serve as the core material and their combination with sodium-conductive structures to core-shell materials. Herein, we will present different synthesis routes towards tailor-made carbon core materials. Moreover, different coatings concepts will be introduced, and the electrochemical performance of the core and core-shell materials compared. To elucidate the storage mechanism, the results of advanced analytical methods such as operando NMR and SAXS will be presented. Generally, these core-shell anodes promise to enable high capacities accompanied with low irreversible losses due to optimized SEI-formation. T2 - GDCh Electrochemistry 2024 CY - Braunschweig, Germany DA - 16.09.2024 KW - Sodium Ion Batteries KW - Negative Electrodes KW - Core Shell Materials KW - Energy Storage PY - 2024 AN - OPUS4-61145 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Valorization of carbon dioxide by the electrocatalytic reduction coupled to acetogens via multiple electron carriers N2 - A summary of the DFG project "Ecat-Acetogens" within the SPP priority programm Ebiotech (2240) was given. The successful developmante of a bioelectrocataltic reactor system based on standard 2l stirred tank bioreactors and common 5cm2 singel cell electrolysis reactors was presnted and first results discussed based on the catlytic properties of a specifically designed cathode catalyst for CO2 reduction. T2 - DFG SPP Statusmeeting Ebiotech 2024 CY - Jena, Germany DA - 22.04.2024 KW - CO2 conversion KW - Bioelectrocatalytic reactor PY - 2024 AN - OPUS4-61939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schwarz, I. A1 - Rieck, Arielle A1 - Fellinger, Tim-Patrick A1 - Weuster-Botz, Dirk T1 - Bio-electrochemical CO2 conversion into organic products using precious-metal free electrocatalysts N2 - For the realization of a sustainable economy, it is of great importance to make use of CO2 for the production of multi-carbon organic chemicals used as feedstock in the chemical industry as well as carbon-neutral fuels (Varela et al. 2019). A promising approach is the electrochemical CO2 reduction followed by microbial conversion of the reduced products. KW - Bio-electrochemical KW - Organic products KW - Electrocatalysts PY - 2024 SP - 1 EP - 2 AN - OPUS4-59572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sander, Luise T1 - Commercially Available Sodium-Ion Cells: Links between Material and Electrode Properties and the electrochemical Performance N2 - As the first commercial sodium-ion-batteries (SIBs) are available for purchase, it is possible to investigate material composition. Gaining an insight into the material composition of these SIBs is of interest not only for the classification of possible safety risks and hazards, but also in regards to recycling. Herein we report the preliminary investigations of the chemical and structural composition of first commercial SIB-cells. Two different SIB-cell types were compared in terms of electrode size, thickness, loading etc. Furthermore, the composition of the active materials and electrolyte was investigated and compared. Finally, the gained results were linked to the different data sheet performance of the two cell types. T2 - MATSUS Conference 2025 CY - Sevilla, Spain DA - 03.03.2025 KW - Battery KW - Sodium-Ion-Battery KW - Electrochemical Energy Storage KW - Energy Storage PY - 2025 AN - OPUS4-62932 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sander, Luise T1 - Linking Material and Electrode Properties to the Cell Performance of Commercially Available SIBs N2 - As the first commercial sodium-ion-batteries (SIBs) are available for purchase, it is possible to investigate material composition. Gaining an insight into the material composition of these SIBs is of interest not only for the classification of possible safety risks and hazards, but also in regards to recycling. Herein we report the preliminary investigations of the chemical and structural composition of first commercial SIB-cells.[1,2] Two different SIB-cell types were compared in terms of electrode size, thickness, loading etc. Furthermore, the composition of the active materials and electrolyte was investigated and compared. Finally, the gained results were linked to the different data sheet performance of the two cell types. T2 - Advanced Battery Power 2025 CY - Aachen, Germany DA - 01.04.2025 KW - Battery KW - Sodium-Ion-Battery KW - Electrochemical Energy Storage KW - Energy Storage PY - 2025 AN - OPUS4-62924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sander, Luise T1 - Comparison of Commercially Available SIBs: Linking Material and Electrode Properties to Cell Performance N2 - As the first commercial sodium-ion-batteries (SIBs) are available for purchase, it is possible to investigate material composition. Gaining an insight into the material composition of these SIBs is of interest not only for the classification of possible safety risks and hazards, but also in regards to recycling. Herein we report the preliminary investigations of the chemical and structural composition of first commercial SIB-cells. Two different SIB-cell types were compared in terms of electrode size, thickness, loading etc. Furthermore, the composition of the active materials and electrolyte was investigated and compared. Finally, the gained results were linked to the different data sheet performance of the two cell types. T2 - Batterieforum 2025 CY - Berlin, Germany DA - 21.01.2025 KW - Battery KW - Sodium-Ion-Battery KW - Electrochemical Energy Storage KW - Energy Storage PY - 2025 AN - OPUS4-62921 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krug von Nidda, Jonas T1 - Single Cell Exchange in Battery Packs – Sustainability vs. Safety Aspects N2 - Lithium-ion batteries usually consist of numerous individual cells. There is ongoing discussion about enhancing sustainability by considering the replacement of heavily aged or damaged cells. Nevertheless, the planned replacement of individual cells poses significant challenges in ensuring the required reliability and safety of the refurbished device. T2 - KLIB Gesprächsrunde Batteriesysteme CY - Online meeting DA - 16.05.2023 KW - Lithium Ion Batteries KW - Lithium Ion Cells KW - Cell Exchange KW - Safety KW - Sustainability PY - 2023 AN - OPUS4-59272 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Overview of Battery Research Activities at BAM N2 - An overview on battery research activities of BAM was given using a seletion of activities of all work packages within the field of activity EES and selected activities of divsion 3.6. T2 - Boot Camp of the BAccara Graduate School on Batteries CY - Bad Sassendorf, Germany DA - 24.04.2024 KW - State of Safety KW - Compositional traceability KW - Sustainable energy materials KW - Sodium Ion Batteries PY - 2024 AN - OPUS4-61940 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Chemie der Energiewende N2 - Es wurde ein Überblick über die BAM-Aktivitäten im Bereich Chemie der Energiewende gegeben. Dabei wurde ein Fokus auf Aktivitäten in Aktivitätsfeld EES und im Fachbereich 3.6 gelegt. T2 - 30 Jahre Naturwissenschaftliches Studium in Zittau CY - Zittau, Germany DA - 13.04.2024 KW - Chemie KW - Energiewende PY - 2024 AN - OPUS4-61941 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Sodium-Ion Battery Research and Testing at BAM N2 - An overview of activities at BAM on the topic of sodium ion batteries was given. Examples of the internal SIB-links project were given and a focus on novel synthetic anodes. T2 - Sodium Battery Sympoium-5 (2024) CY - Berlin, Germany DA - 23.09.2024 KW - Sodium ion batteries KW - Synthetic carbon anodes PY - 2024 AN - OPUS4-61944 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick A1 - Krug von Nidda, Jonas T1 - Porous „Ionophoric“ Carbon Materials: Synthesis Routes and Electrochemical Applications N2 - Porous carbon materials play an important role for energy storage and conversion, e.g., as fuel cell catalysts, supercapacitor or battery electrodes. Tuning porosity features such as pore connectivity, specific surface area, maximum pore size and pore volume is one of the key strategies to improve the performance of those materials.[1] Moreover, the alteration of the chemistry allows further enhancement in performance, even leading to the applicability in new fields. In this context, nitrogen doped carbons (NDCs) are a very promising material class. Highly porous NDCs for example show interesting Na-storage features.[2] Moreover, the integration of iron ions in an NDC, forming FeN4-sites, can results in materials with very promising properties as fuel cell cathode catalysts.[3] However, to relate certain sites to specific performance indicators is still challenging as the variation of the present N-sites is very large in typically obtained NDCs. In the past, we were able to develop an ionothermal synthesis strategy which results in highly porous materials with specific, i.e., tetrapyrrolic, N4-sites.[4] Such N4 sites and there metal complexes are reminiscent of biomolecules like the heme molecule, which originally inspired the research on such materials.[5] The N4-sites are mainly occupied by Zn2+ as the synthesis is performed in a ZnCl2-containing salt melt. Moreover, the electrochemical performance of those materials can be rather easily altered upon removing/exchanging the Zn2+. Moreover, again looking at biomolecules, those kind of materials can be regarded as ionophoric carbons as they possess distinct, metal-binding N4-sites embedded in a carbon matrix. Herein, we will focus on the synthesis of zeolitic imidazolate framework (ZIF) based NDCs with high porosity. We will discuss different strategies to remove and/or exchange Zn2+ in the obtained ZnN4-containing materials. Different analytical methods, e.g., physisorption (N2, Ar, CO2), XPS, XAS, and NMR, will be used to understand the alteration of morphological and chemical features upon ion exchange (see Figure 1). Figure 1: A) Schematic illustration of the partial Zn-removal in a ZnN4-containing, ionophoric carbon. B) High resolution N 1s XPS-results of a ZIF-derived ionophoric carbon before and after metal leaching. Due to the ion exchange/removal, the chemistry of the NDCs is altered, however, typically preserving the porosity features as well as the general structure of the N-motifs. Thus, the influence of the occupancy of the N4-sites on the electrochemical performance can be studied in detail. Finally, structure-property-relations of the different ZIF-derived ionophoric NDCs regarding the performance as anodes in sodium ion batteries will be discussed. T2 - Deutsche Zeolith-Tagung 2024 CY - Jena, Germany DA - 28.02.2024 KW - Ionophoric carbon KW - Sodium ion battery KW - PGM-free catalysts PY - 2024 AN - OPUS4-61955 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Sol-gel synthesis of porous boron- and nitrogen-doped carbon N2 - Carbon activation is intensively investigated due to a widespread utilization of activated carbons as sorbents, hosting and support materials owning to its high porosity and surface area. Activated carbons are increasingly considered also for electrochemical applications e.g. supercapacitors and metal-ion hybrid capacitors. Those devices usually employ activated carbon electrodes, where ions are stored by means of adsorption/desorption.[1] Meanwhile, in lithium-sulfur batteries, sulfur is loaded within activated carbon pores to confine insoluble intermediates.[2] The activation is normally proceeded in top-down or bottom-up strategies. Therein pore formation (porogenesis) occurs by reaction with steam, CO2, KOH, or the use of acidic agents. It is generally accepted, that the porogenesis mechanism is chemical leaching of carbon atoms. Recently, the sol-gel type synthesis of nitrogen-doped carbon in molten acids was presented, questioning the general validity of a leaching activation mechanism.[3] The protocol using inorganic salt melts (MgCl2 or ZnCl2) and organic precursors additionally generated N-functionalities. Interestingly, it can be noticed that the imprinting cations play a crucial role towards chemical structure of nitrogen-doped carbon framework. The coordinated geometry is well-known from phthalocyanine, a macrocyclic N-complexes (MN4-sites, where M is metal cation) which are desirable surface complexes, e.g. in electrocatalysis. The analogous phenomenon may be observed when using H3PO4 and H3BO3 agent via sol-gel chemistry.[4] Herein, the carbonization of mixtures of organic compound with H3PO4 and H3BO3 is investigated. Therefore, associated effects regarding the presence of P and B atoms within resulting nitrogen-doped carbons as well as the porogenesis mechanism are discussed. The understanding of moieties probably offers a new perspective of non-leaching carbon activation hence, provides a feasible pathway towards improved performances in electrochemical applications. T2 - Deutsche Zeolith-Tagung 2022 CY - Frankfurt am Main, Germany DA - 24.03.2022 KW - B-N-C KW - Boric acid activation PY - 2022 AN - OPUS4-61957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - DialySorb und Eigenschaften kommerzieller Zellen N2 - In dem Vortrag wurden zunächst die Eigenschaften erster kommerzieller Natrium-Ionen-Batterien vorgestellt, die an der BAM elektrotechnisch untersucht wurden und auf ihre Bestandteile hin analysiert wurden. Weiterhin wurden die aktuellen Projektergebnisse des BMBF-geförderten Verbundprojekts Dialysorb vorgestellt. T2 - KLiB-Gesprächsrunde zu Natrium-Ionen-Batterien und Festkörperbatterien CY - Frankfurt am Main, Germany DA - 09.07.2024 KW - Natrium-Ionen-Batterien PY - 2024 AN - OPUS4-61942 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Leveraging the Potential of Na-Ion-Batteries with Tailormade Anodes N2 - The concept of sodium-ion-batteries and their expected impact for the energy change is introduced, by explaining differences to lithium-ion-batteries. The challenge as well as the potential may be illustrated on the example of novel carbon anodes.While the general suitability is proven since the recent commercialization, limitations and detailed structure-performance relations remain topic to research. The progress in activities of BAM division 3.6 are illustrated further supporting the future impact of the technology. T2 - TechConnect Adlershof 2024: Sustainable Energy Future CY - Berlin, Germany DA - 09.11.2024 KW - Synthetic Carbon Anodes PY - 2024 AN - OPUS4-61947 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Porous Carbon Supported Ni or Co Single Atom Catalysts for Electrochemical Reduction of CO2 N2 - Isomorphous, but chemically unequal Ni-, Co- and Zn-N-C electrocatalysts are investigated for their electrocatalytic properties towards the electrochemical CO2 conversion. It turns out that Ni-N-Cs are clearly most favourable, because of the isomorphism to other catalysts, also clearly due to the NiN4 sites properties. T2 - Deutsche Zeolith-Tagung 2024 CY - Frankfurt am Main, Germany DA - 23.03.2024 KW - M-N-C catalysts KW - CO2 reduction PY - 2022 AN - OPUS4-61953 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Research on Synthetic Anodes for Na-Ion-Batteries N2 - Carbons with an amorphous structure are currently revisited as candidates for Li- and Na-ion batteries. High irreversible capacities (due to SEI formation) were considered an intrinsic problem of such hard carbons, rendering them irrelevant for practical use. Amorphous carbon anodes would present safety-related advantages such as lower heat dissipation throughout lithiation per mol of lithium, mechanical stability throughout cycling and a larger set of optional electrolytes. T2 - Advanced Automotive Battery Conference Europe 2024 CY - Strasbourg, France DA - 13.05.2024 KW - Synthetic Carbon Anodes PY - 2024 AN - OPUS4-61956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geisler, J. T1 - The Influence of Interface Modification on Gassing of Sodium Ion Battery Anodes N2 - This flash talk will briefly introduce the DEMS method[3,4] and highlight a recent piece of our research from the DIALYSORB project. Fitting to the main topic of the conference, interfaces, we will present and the measurement technique to understand the side reactions occurring at this interface and recent data on anode materials with designed interface and interphase. T2 - Humboldt Universität zu Berlin CY - Berlin, Germany DA - 17.09.2024 KW - Gasing of Sodium KW - Ion Battery KW - Anodes PY - 2024 AN - OPUS4-60811 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mehmood, Asad T1 - Atomically Coordinated Non-Precious Metal Electrocatalysts Using Active Site Imprinted Carbon Matrix N2 - Non-precious metal catalysts generally represented as M-N-C (where M= Fe, Co, Ni etc.) have shown encouraging activity levels for different electrochemical applications involving oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO2RR). High activities of these electrocatalysts mainly come from transition metal centres that are atomically dispersed as M-N4 active sites within a nitrogen doped carbon matrix. Because of the required pyrolytic synthesis conditions, it is quite challenging to prepare M-N-Cs that purely consist of M-N4 active sites. Classical synthesis routes often result in the formation of additional side phases such metallic nanoparticles or metal carbides, which limit the density of M-N4 sites and lead to lower catalytic activity.1 Herein, we present our work on M-N-C synthesis using an active site imprinting approach as an alternate synthetic route to address the above-mentioned issue. We show that both Mg and Zn can be used for active site imprinting. The imprinted coordination environment can be coordinated with various transition metal ions, resulting in Fe-N-C, Co-N-C and Ni-N-C catalysts containing M-N4 sites exclusively.2-4 The electrochemical performance of the synthesized catalysts is evaluated for CO2RR and ORR. Ni-N-Cs exhibit an excellent CO2 reduction activity with high CO faradic efficiency value of 95% at U= -0.5 to -0.8 VRHE (vs reversible hydrogen electrode) and a mass activity of 23 A g-1. The performance stability test carried out at -0.65 VRHE demonstrates above 92 % retention of the current density and 97 % retention of the CO selectivity after 100 h of continuous operation, reflecting the structural robustness of the Ni-N-C catalyst in CO2RR test environment. When employed as ORR catalysts, both Fe-N-C and Co-N-C deliver promising activities with half-wave potentials >0.8 VRHE in acidic electrolyte and >0.9 VRHE in alkaline electrolyte. The talk will include greater details of the structural analysis and electrochemical performance evaluation of these catalysts. T2 - 73rd Annual Meeting of the International Society of Electrochemistry CY - Online meeting DA - 12.09.2022 KW - Non-precious metal catalysts KW - Single atom catalysts KW - Electrochemical CO2 conversion PY - 2022 AN - OPUS4-61986 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mehmood, Asad T1 - Ionothermal Template Transformation as a Sustainable Route Towards Carbon Electrodes in Energy Storage and Conversion N2 - Porous carbons with tuneable functionalities and morphologies have extensively been employed as electrode materials in a variety of electrochemical energy conversion and storage systems for instance in fuel cells and electrolysers as active catalysts and catalyst supports, and in secondary batteries as anode materials. Amorphous carbons with well-developed pore structures are of particular interest due to their superior mass-transport characteristics and remarkable charge storage capacities. The salt-templating method with its advantage of combined soft and hard templating effects provides a sustainable way to synthesize nano- and mesoporous carbons with tailored porosities via in-situ ionothermal template transformation [1]. In this work, we utilized a MgCl2-based salt melt to prepare nitrogen doped carbons (N-C) with different morphologies and porosities, which were evaluated as anode materials in sodium ion batteries. Simultaneously, use of MgCl2 salt leads to the formation of Mg-N4 moieties in those carbons by means of a pyrolytic template-ion effect (active site imprinting) [2]. Porous carbon frameworks with imprinted Mg-N4 sites are interesting particularly for electrocatalysis applications as they offer an ideal platform to prepare M-N-C catalysts (where M= Co, Fe, Ni etc.) by ion-exchange reactions at low temperatures. The resultant M-N-C catalysts consist purely of M-N4 active sites and high porosity of carbon framework facilitates efficient mass-transport of reacting species. We utilized Mg-N4 imprinted carbons to synthesize morphologically equivalent Ni-N-Cs and Co-N-Cs, containing phase pure Ni-N4 and Co-N4 sites, for electrochemical reduction of carbon dioxide (CO2RR). In electrochemical tests, Ni-N-Cs exhibited an excellent CO2 reduction activity with considerably higher CO selectivity and mass activity as compared to Co-N-C. The faradic efficiency value of Ni-N-C for CO formation was 95% at U= -0.5 to -0.8 VRHE (vs reversible hydrogen electrode) and a mass activity of 23 A g-1. The performance stability test carried out at -0.65 VRHE demonstrated above 90 % retention of the current density and CO selectivity after 100 h of continuous operation, reflecting the structural robustness of the Ni-N-C catalyst. Finally, these ionothermal carbons with two different morphologies (but without any Ni or Co incorporation) were employed as the anode materials in sodium-ion batteries to evaluate the effects of carbon morphology and functionalization on sodium storage capacities. Compared to the reference carbon material, substantially higher reversible sodium storage capacities were reached with these high porosity carbons that were in the range of 300-500 mAh g-1 [3]. Although the reversible capacity was obtained only after extensive SEI formation, our results reveal the potential for much higher reversible capacities than usually observed using carbons with a tailored porosity in sodium-ion batteries. The talk will include greater details of the structural analysis and sodium storage and CO2 reduction results of these ionothermal carbons. T2 - Materials for Sustainable Development Conference (MAT-SUS) CY - Barcelona, Spain DA - 24.10.2022 KW - Porous carbons KW - Sodium ion batteries KW - Anode materials KW - Single atom catalysts KW - Electrochemical CO2 reduction PY - 2022 AN - OPUS4-61985 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Bioinspired atomically dispersed M-N-C catalysts via active-site imprinting into nitrogen doped carbons N2 - Proton-exchange membrane fuel cells are amongst the most promising energy conversion technologies today. Herein non-precious iron-coordinated nitrogen doped carbons (Fe-N-Cs) are very promising alternatives for Pt-based cathode catalysts.[1-3] The early reports on the application of such materials date back to the 1960´s when Jasinski demonstrated that - similar to natural porphyrins - N-coordinated transition metal complexes can be active sites for the ORR.[3] The preparation of these catalysts was strongly optimized over the years; still they typically remain with harsh reaction conditions that complicate the selective formation of active FeN4 sites. The employment of pyrolytic temperatures has been a dogma for the synthesis of MN4 sites, however coming with unfavorable side reactions. We recently introduced a mild procedure, which is conservative toward the carbon support and leads to active-site formation at low temperatures in a wet-chemical step, essentially decoupling the preparation of nitrogen doped carbons (NCs) from the preparation of the active sites.[4, 5] The key concept therein is the so-called active site imprinting into the NC using the less reactive template ions Mg2+ [4] or Zn2+.[5] The presentation will introduce the concept of active site imprinting with a focus on Fe-N-C electrocatalyst development and testing. The broad potential of the synthetic approach will be exemplified by recent results, including the selective synthesis of tetrapyrrolic single site catalysts, the assignment of the role of the transition metal compared to the carbon scaffold and a facile method to evaluate specific activity. T2 - GDCh Electrochemistry 2022 CY - Berlin, Germany DA - 27.09.2022 KW - Bioinspired carbon catalysts PY - 2022 AN - OPUS4-61960 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krug von Nidda, Jonas T1 - Separating Initial Loss from Storage Capacity: Core-Shell Materials as Advanced Anode Materials for Sodium Ion Batteries N2 - The current imperative to shift towards an energy grid equipped with sustainable energy storage solutions has caused a renewed interest in sodium-ion batteries (SIBs). Hard carbons (HCs) are a promising option high-capacity anode materials in SIBs. Nevertheless, their elevated capacities frequently come at the cost of experiencing substantial non-reversible initial capacity losses Commonly, significant losses are associated with irreversible reactions, such as the creation of the solid electrolyte interphase (SEI), that occur during the initial sodium insertion in HC-materials. Intriguingly, high values of irreversible capacity are often found for samples with experimentally determined low specific surface area.[1] A more comprehensive understanding of the structure-property relations is essential for quantifying and grasping the potential of hard carbon materials in sodium-ion batteries (SIBs). Thus, the objective is to employ analytical methods to establish a link between the structure and the electrochemical attributes of HC materials. This has been a challenge, partly due to the non-stoichiometric nature of the sodium storage mechanism and the disordered structure of HCs. To address the challenges mentioned above, our approach is to explore whether a core-shell structure can separate sodium storage and SEI-formation. This way, we can investigate and fine-tune storage capacity and irreversible losses, independently. The strategy involves the synthesis of various porous carbon structures to serve as the core material and their combination with sodium-conductive structures to core-shell materials. Herein, we will present different synthesis routes towards tailor-made carbon core materials. Moreover, different coatings concepts will be introduced, and the electrochemical performance of the core and core-shell materials compared. To elucidate the storage mechanism, the results of advanced analytical methods such as operando NMR and -SAXS will be presented. Generally, these core-shell anodes promise to enable high capacities accompanied with low irreversible losses due to optimized SEI-formation. T2 - Advanced Battery Power Conference 2024 CY - Münster, Germany DA - 10.04.2024 KW - Battery KW - Anode KW - Hard Carbon PY - 2024 AN - OPUS4-61968 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Effects of Acid Activation via Sol-Gel Chemistry towards Nitrogen-Doped Carbon Structure N2 - Porous carbon materials are known for their applicability in important areas such as sorption, catalysis and electrochemistry (e.g. fuel cell catalysts, supercapacitor or battery electrodes). It was shown that nitrogen doped carbons (NDCs) act as an inexpensive and highly active non-metal catalyst in the oxygen reduction reaction (ORR), with the potential to reach performances of practical need one day. A key strategy towards improvement for this aim comprises the generation of advantageous porosity, which typically means high surface area and mass transport pores as well as the control over the chemistry of catalytically active sites. My group is developing novel sol-gel type strategies that are using molten salts or molten acids as unconventional reaction medium for the porogenesis in doped carbons, thereby revisiting classic activation techniques.[1,2] Carbon materials with extra high surface area of ~2800 m2 g- 1 and pore volumes, up to four times as high as in commercial activated carbons, are obtained.[3] It turns out that the meso- and macrostructure is generated by means of phase separation rather than leaching reactions. However, chemical reactions between the carbon precursor and the melt are also involved. The salt cations Mg2+ and Zn2+ act as template ions, which results in metal coordination sites, embedded into the carbon structure.[4,5] The imprinted structure may be utilized as catalytically active site by performing ion-exchange reactions. The novel preparation strategy towards highly active electrocatalysts will be presented for Mg and Zn and further discussed for lighter elements. T2 - International Sol-Gel Conference 2022 CY - Lyon, France DA - 24.06.2022 KW - Sol-Gel-Carbonization KW - Boron-Nitrogen-Doped Carbon PY - 2022 AN - OPUS4-61958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wutthiprom, Juthaporn T1 - Sol-Gel Carbonization towards Tailor-Made Boron- and Nitrogen-doped Carbon N2 - The activation of carbon is normally proceeded in top-down or bottom-up strategies. Therein pore formation (porogenesis) occurs by reaction with steam, CO2 , KOH, or the use of acidic agents, in which chemical leaching of carbon atoms occurs. The sol-gel type synthesis of N-doped carbon in excess amounts of molten acids was presented recently, questioning the general validity of a leaching activation mechanism.[1] The protocol using inorganic salt melts (MgCl2 or ZnCl2 ) and organic precursors additionally generated N functionalities. Interestingly, it can be noticed that the imprinting cations play a crucial role towards the chemical structure of N-doped carbon framework. The coordinated geometry is wellknown from phthalocyanine, a macrocyclic Ncomplexes (MN4 -sites, where M is metal cation) which are desirable surface complexes, e.g. in electrocatalysis. The analogous phenomenon may be observed when using H3BO3 agent via sol-gel chemistry. T2 - International Sol-Gel Conference 2022 CY - Lyon, France DA - 24.06.2022 KW - Boron-Nitrogen-Doped-Carbon KW - Sol-Gel-Carbonization PY - 2022 AN - OPUS4-61959 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mehmood, Asad A1 - Fellinger, Tim-Patrick T1 - Porous Carbon Supported Ni and Co Single Atom Catalysts for Electrochemical Reduction of Carbon Dioxide N2 - Non-precious metal single atom catalysts (generally labelled as M/NCs where M= Co, Fe, Ni etc.) consist of active metal centres dispersed on nitrogen doped porous carbon (NC) matrix at atomic level and exhibit promising activities e. g. for electrochemical reduction of CO2, selectively forming CO. We herein use identical Mg/NCs as platform for ion-exchange reactions towards morphologically equivalent Ni/NCs and Co/NCs. The Ni/NC catalyst shows almost double the specific activity and a Faraday efficiency of >80% at a very low overpotential of U= -0.43 V (even 95% at U= -0.5 to -0.8 V) with high stability. T2 - GDCh Electrochemistry 2022 CY - Berlin, Germany DA - 27.09.2022 KW - Electrochemical CO2 conversion KW - Single atom catalysts KW - Porous Carbons PY - 2022 AN - OPUS4-61980 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dietzmann, Simon T1 - Synthesis of Atomically Dispersed Electrocatalyst by Imprinting with Different Template Ions throughout Carbonization N2 - Atomically dispersed metal-nitrogen doped carbons (M-N-C) are promising catalysts for the activation of small molecules such as O2 and CO2. These single atom catalysts (SAC) operate at the interface between homogenous and heterogenous catalysts. Currently, many examples of M-N-C are known with good oxygen reduction reaction activity but lacking a controlled synthesis of the specific active sites of the precatalyst. T2 - GDCh Electrochemistry 2022 CY - Berlin, Germany DA - 27.09.2022 KW - Elechtrochemistry KW - Oxygen reduction reaction KW - Porous carbons PY - 2022 AN - OPUS4-61982 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Appel, Paul Alexander T1 - Developing Tailor-Made Core-Shell Carbon Anode Materials for Sodium Ion Batteries N2 - The current strong interest in electromotive mobility and the need to transition to an energy grid with sustainable energy storage has led to a renewed interest in sodium ion batteries (SIBs). Hard carbons are promising candidates for high-capacity negative electrode materials in SIBs. Their high capacities, however, are often accompanied with high irreversible capacity losses during the initial cycles.[1] The goal of this project is to use analytical techniques to establish a correlation between the structure and the capacities of hard carbons. This has previously been difficult, in part because the sodium storage mechanism is not stoichiometric and due to the disordered structure of hard carbons. Large irreversible capacities associated with hard carbons are often in contradiction to the experimentally determined low surface area of the sample material.[1] A better understanding of the structure-property relationship should enable quantification and understanding of the potential of hard carbon materials for SIBs. Our approach is to explore whether a core-shell structure can separate sodium storage and solid electrolyte interphase formation so that storage capacity and irreversible losses can be investigated separately. The synthesis of a selection of porous carbon structures serving as the core material, will be attempted. Simultaneously, sodium-conducting shell structures will be developed to allow for separation of sodium ions and electrolyte molecules. Subsequently the combination of core and shell materials will be undertaken. These anodes should enable high capacities accompanied with low irreversible capacity due to optimized solid electrolyte interphase formation. T2 - ECS Gothenburg CY - Gothenburg, Sweden DA - 08.10.2023 KW - Energy Materials PY - 2023 AN - OPUS4-62003 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Appel, Paul Alexander T1 - Development of tailormade core-shell hard carbon materials as anode materials in sodium ion batteries N2 - The current strong interest in electromotive mobility and the need to transition to an energy grid with sustainable energy storage has led to a renewed interest in sodium ion batteries (SIBs). Hard carbons are promising candidates for high-capacity negative electrode materials in SIBs. Their high capacities, however, are often accompanied with high irreversible capacity losses, during the initial cycles.[1] The goal of this project is to synthesize carbon materials using different zeolite templates to obtain electrode materials that feature a defined and adjustable pore structure. A better understanding of the structure-property relationship by investigating porosity-tailored anode materials, should enable quantification and understanding of the potential of hard carbon materials for SIBs. Furthermore, a goal is to explore whether a core-shell structure can separate sodium storage and solid electrolyte interphase formation allowing the independent investigation of storage capacity and irreversible losses. T T2 - 34. Deutsche Zeolith-Tagung CY - Vienna, Austria DA - 21.02.2023 KW - Energy Materials PY - 2023 AN - OPUS4-62002 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wu, Shu-Han T1 - Synthetic Carbon Anodes for SIBs N2 - Hard carbon (HC) is currently one of the most promising anode materials for sodium-ion batteries (SIBs). However, the Na storage mechanism remains controversial, leaving the theoretical limits carbon anodes unclear. To deconvolute the specific capacity from irreversible capacity losses resulting from the formation of solid electrolyte interphase (SEI), core-shell carbon materials with tailored pore structure and defined surface functionalities are synthesized. Meanwhile, these synthetic designer carbons could achieve more competitive capacities for use as better anodes for SIBs. T2 - Adlershofer Forschungsforum (AFF) CY - Berlin, Germany DA - 11.11.2024 KW - Na-ion Battery PY - 2024 AN - OPUS4-61998 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wu, Shu-Han T1 - Mole sieving, artificial cathode electrolyte interphase enables stable cycling of room temperature sodium sulfur cells N2 - Porous carbon particles derived from zeolitic imidazolate framework (ZIF-8) were used as a matrix to improve the electrode conductivity and buffer the volume change of sulfur (S). In addition, the porous carbon particles were coated with an additional ion-sieving tailor-made covalent organic framework (COF) shell, which can be regarded as an artificial cathode electrolyte interphase (CEI). The introduced shell can avoid polysulfides from dissolving in the ether-based electrolyte, thus, preventing the shuttling of polysulfides. The as-synthesized sulfur-infiltrated core-shell cathode delivers a reversible capacity of 975 mAh gS–1 (@C/33) and a reasonable rate capability. T2 - 5th International Sodium Battery Symposium, SBS-5 CY - Berlin, Germany DA - 23.09.2024 KW - NaS Battery PY - 2024 AN - OPUS4-61992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Appel, Paul Alexander T1 - Investigation and Development of Tailor-Made Core-Shell Hard Carbon Materials to be used as Negative Electrodes in Sodium Ion Batteries N2 - The current strong interest in electromotive mobility and the need to transition to an energy grid with sustainable energy storage has led to a renewed interest in sodium ion batteries (SIBs). Hard carbons are promising candidates for high-capacity negative electrode materials in SIBs. Their high capacities, however, are often accompanied with high irreversible capacity losses during the initial cycles.[1] The goal of this project is to use analytical techniques to establish a correlation between the structure and the capacities of hard carbons. This has previously been difficult, in part because the sodium storage mechanism is not stoichiometric and due to the disordered structure of hard carbons. Large irreversible capacities associated with hard carbons are often in contradiction to the experimentally determined low surface area of the sample material.[1] A better understanding of the structure-property relationship should enable quantification and understanding of the potential of hard carbon materials for SIBs. Our approach is to explore whether a core-shell structure can separate sodium storage and solid electrolyte interphase formation so that storage capacity and irreversible losses can be investigated separately. The synthesis of a selection of porous carbon structures serving as the core material, will be attempted. Simultaneously, sodium-conducting shell structures will be developed to allow for separation of sodium ions and electrolyte molecules. Subsequently the combination of core and shell materials will be undertaken. These anodes should enable high capacities accompanied with low irreversible capacity due to optimized solid electrolyte interphase formation. T2 - GDCH Electrochemistry 2022 CY - Berlin, Germany DA - 27.09.2022 KW - Energy Materials PY - 2022 AN - OPUS4-62001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dietzmann, Simon T1 - X-Ray Absorption Spectroscopy to Reveal the „Molecular“ Structure of Metal and Nitrogen doped Carbon Electrocatalysts N2 - High-performance electrocatalysts and sodium-ion (Na+) storage materials for Na-ion batteries anodes are required for energy conversion and storage systems. Metal and nitrogen enriched carbons (M-N-Cs) are promising candidates as they are conductive and can be tuned to the desired properties by appropriate modification. Structural characterization is essential to understand and optimize the active sites at the pseudo-molecular level and the storage of Na+ in the anode T2 - Bessy User Meeting CY - Berlin, Germany DA - 11.12.2024 KW - Single-atom-catalyst KW - Electrochemistry KW - Porous carbons PY - 2024 AN - OPUS4-62074 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Appel, Paul Alexander A1 - Prinz, Carsten A1 - Low, Jian Liang A1 - Asres, Nahom Enkubahri A1 - Wu, Shu-Han A1 - Freytag, Annica A1 - Krug von Nidda, Jonas A1 - de Sousa Amadeu, Nader A1 - Fellinger, Tim-Patrick T1 - Kern–Schale: Versiegelung nanoporöser Partikel mit semipermeablen Kohlenstoffschichten befreit Hartkohlenstoffanoden von ihrem Dilemma N2 - In der vorliegenden Arbeit wird eine Kern-Schale-Strategie vorgestellt, die das grundlegende Problem gängiger nichtgraphitischer Hartkohlenstoff-Anoden adressiert: Hohe reversible Kapazitäten gehen bislang typischerweise mit erheblichen irreversiblen Verlusten in den ersten Zyklen einher. Analog zu Graphit, das sowohl Lithiumspeicherung als auch die Abtrennung von Elektrolytlösungsmitteln in einer homogenen Struktur vereint, zeigen wir, dass sich diese beiden Funktionen auch in nichtgraphitischen Kohlenstoffen gezielt in einer heterogenen Architektur kombinieren lassen. Hochporöse Aktivkohlen werden durch kinetisch kontrollierte Gasphasenabscheidung mit einer dünnen Schicht nichtgraphitischen Kohlenstoffs überzogen, sodass eine funktionale Kern-Schale-Struktur entsteht. Gasadsorptionsmessungen an Kern-, Schalen-, Kern-Schale- und mechanisch beschädigte Kern-Schale-Partikeln, bestätigen, dass die Porosität des Kerns erhalten bleibt und die Schale semipermeabel ist. Die Sorption von Diethylcarbonat wird als geeignetere Methode im Vergleich zu N2- oder CO2-Sorptionsmessungen eingeführt, um die irreversiblen Verluste des ersten Zyklus mit der tatsächlichen Flüssig-Fest-Grenzfläche von Kohlenstoffanoden zu verknüpfen. Die funktionalen Kern-Schale-Partikel zeigen eine stark reduzierte Aufnahme von Diethylcarbonat, was hohe reversible Kapazitäten bei deutlich geringeren Erstzyklusverlusten ermöglicht. Bei einer reversiblen Kapazität von 400 ± 24 mAh g−1 und einer initialen Coulombeffizienz von 82 ± 2% zeigt sich, dass die dreistufige Natriumspeicherung in der gezielt entwickelten Kern-Schale-Architektur den größeren Ionenradius von Natrium gegenüber Lithium (372 mAh g−1 in Graphit) kompensieren kann. Die entwickelten Kern-Schale-Anoden erreichen damit ein Leistungsniveau, das für eine kommerzielle Anwendung vielversprechend ist. KW - Kern-Schale-Struktur KW - Natriumionenbatterie KW - Hartkohlenstoffanode KW - Diethylcarbonatdampfsorption KW - Aktivkohle PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655354 DO - https://doi.org/10.1002/ange.202519457 SN - 1521-3757 N1 - Es gibt eine parallele Sprachausgabe (englisch), ein Link befindet sich im Feld zugehöriger Identifikator - There is a parallel language edition (English), a link is in the field related identifier SP - 1 EP - 10 PB - Wiley-VCH CY - Weinheim AN - OPUS4-65535 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Appel, Paul Alexander A1 - Prinz, Carsten A1 - Low, Jian Liang A1 - Asres, Nahom Enkubahri A1 - Wu, Shu-Han A1 - Freytag, Annica A1 - Krug von Nidda, Jonas A1 - de Sousa Amadeu, Nader A1 - Fellinger, Tim-Patrick T1 - Core‐Shell: Resolving the Dilemma of Hard Carbon Anodes by Sealing Nanoporous Particles With Semi‐Permeable Coatings N2 - A core-shell strategy is introduced to overcome the dilemma of common non-graphitic hard carbon anodes, linking high reversible storage capacity to practically unacceptable irreversible losses in the first cycle(s). Just as Graphite homogeneously combines effective lithium storage with an electrolyte solvent-sieving function, we show that both of these functions could be strategically integrated into non-graphitic carbons in a heterogeneous structure. Highly porous activated carbons are sealed by kinetically tuned gas-phase deposition of non-graphitic carbon to form a functional core-shell structure. Gas sorption porosimetry on core, shell, core–shell, and cracked core-shell particles confirms preserved core porosity and a semi-permeable shell. Diethyl carbonate sorption analysis is introduced as a more suitable probe than N2 or CO2 sorption, linking first-cycle losses to the liquid–solid interface of carbon anodes. The functional core-shell particles with much reduced diethyl carbonate uptake allow for high storage capacity and reduced first cycle losses. Delivering 400 ± 24 mAh g−1 with 82 ± 2% first-cycle reversibility, it is shown that three-stage Na storage in designed core-shell anodes can compensate for the larger size of sodium compared to lithium stored in graphite anodes (372 mAh g−1). The designed core-shell anodes show state-of-the-art performance with commercial promise. KW - Sodium-ion battery KW - Activated carbon KW - Core-shell KW - Hard carbon anode KW - Diethyl carbonate vapor sorption PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655346 DO - https://doi.org/10.1002/anie.202519457 SN - 1433-7851 N1 - Es gibt eine parallele Sprachausgabe (deutsch), ein Link befindet sich im Feld zugehöriger Identifikator - There is a parallel language edition (German), a link is in the field related identifier SP - 1 EP - 9 PB - Wiley-VCH CY - Weinheim AN - OPUS4-65534 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pedersen, Angus T1 - Coupling Single Atom Electrocatalysts with a Bioreactor for CO2 to C2+ Conversion N2 - To alleviate CO2 emissions impact on climate change, and close the carbon cycle, converting carbon dioxide into valuable products such as multi-carbon organic chemicals is of great importance. Each approach offers distinct merits but also certain challenges in terms of process efficiency, product selectivity and implementation at scale. Developing coupled CO2 conversion systems, for instance bio-electrochemical reactors, can address some of the challenges.[1] Precious-metal free biocompatible single atoms in N-doped C (M-N-C, where M = Fe, Ni, Co) electrocatalysts, based on Mg active site imprinting of bioinspired MN4 sites,[2][3] have shown state-of-the-art activity and selectivity for conversion of CO2 to CO.[4] Pyrolysis of Mg-N-C is carried out in a salt-melt at high temperatures (≥ 800 oC) and followed by an exchange with stoichiometric amounts of Ni or Co at low temperatures. N2-sorption of the materials reveal a micro-mesoporous structure with high surface areas (> 1000 m2 g-1) and a mass-transport enabling pore system. Extended X-ray absorption fine structure reveal the existence of atomically dispersed single atom active sites with defined active site structure. These catalysts were implemented in a home-made bio-electrocatalytic system (BES) consisting of a bioreactor coupled to a CO2 electrolysis cell.[5] Here, CO2 is first electrochemically converted to CO in the electrolysis cell which is then directly fed to bacteria (Clostridium ragsdalei) in the bioreactor which further metabolize it to valuable carbon compounds, such as acetate. An acetate formation rate of 1.8 mg L-1 h-1 was achieved and an acetate concentration of 0.103 g L-1, corresponding to acetate formation rate of 0.73 mmol d-1. We have successfully demonstrated the validity of a coupled bio-electrocatalytic system operating with resource efficient single atom Co- and Ni-N-C electrocatalysts for CO2 conversion. T2 - Electrifying Organic Synthesis CY - Mülheim an der Ruhr, Germany DA - 03.09.2025 KW - Single atom KW - Electrochemical CO2 conversion KW - Bioelectrolysis PY - 2025 AN - OPUS4-64037 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mehmood, Asad T1 - ZIF-derived Atomically Dispersed Non-precious Metal Catalysts (M-N-C) for Electrochemical Energy Applications N2 - Zeolitic imidazolate frameworks (ZIFs) which are a subtype of metal organic frameworks (MOFs) have been extensively used to prepare catalyst materials for a variety of electrochemical reactions for energy conversion and storage applications. Most notable examples of ZIFs used for that purpose include ZIF-8 and ZIF-67 etc. Particularly ZIF-8 with its high surface area, defined pore structure and tunable particle size is widely utilized as a platform material to prepare so-called metal- and nitrogen-doped carbon (M-N-C) catalysts with M= Co, Fe, Ni, Zn etc., which are an emerging class of catalyst materials and consist of nitrogen-doped porous carbon matrix hosting atomically distributed active metal sites.[1, 2] The active sites in M-N-Cs ideally have M-N4 coordination resembling to metal centres in macromolecules such as porphyrins and phthalocyanines.[3] Most representative examples of M-N-Cs include Fe-N-Cs, Co-N-Cs and Ni-N-Cs etc. which are showing promising activities for a variety of electrochemical reactions e.g. oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR) and hydrogen evolution reaction (HER). The structures of M-N-C catalysts are quite complex and require a fine balance between morphological, electronic, and chemical properties to reach optimal electrocatalytic activities. In this talk, I will present our activities on (i) preparation of phase-pure M-N-C catalysts derived from ZIF-8 via active-site imprinting [4, 5] and highlight the benefits of our strategy to achieve high density of active sites and enhanced electrochemical performance levels [6] and (ii) feasibility of using gas physisorption techniques as a new approach to quantify active sites in M-N-Cs. The challenges of maximizing active site utilization and eliminating unfavourable mass-transport characteristics faced by ZIF-8 derived M-N-Cs in electrochemical energy devices e.g. fuel cells will also be briefly discussed. T2 - Materials for Sustainable Development Conference (MAT-SUS) CY - Sevilla, Spain DA - 03.03.20225 KW - Electrochemical energy conversion KW - Single atom catalysts KW - Electrochemical CO2 reduction KW - Fuel cells KW - Electrolyzers PY - 2025 DO - https://doi.org/https://doi.org/10.29363/nanoge.matsusspring.2025.251 AN - OPUS4-62927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Batteries: Basics, Challenges and Trends N2 - In this lecture the fundamental principles of batteries are briefly introduced aligned by the historical development of the technology. The introduction is continued with an overview on current challenges regarding performance, durability, sustainability, cost and safety. Lastly, research trend on approaches to tackle the challenges are discussed by selected examples. T2 - 2025 Scientific and Technological Training Course "Design and Evaluation Methods of Fire Safety Engineered Materials" CY - Hefei, China DA - 20.10.2025 KW - Fundamentals of Batteries KW - Safety KW - Active Materials KW - Research Topics PY - 2025 AN - OPUS4-64917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Appel, Paul Alexander T1 - Connecting Porosity to Storage Capacity: Core-Shell Carbon Material As High-Capacity Negative Electrodes for Sodium Ion Batteries N2 - Due to abundant raw materials, low costs and promising high reversible specific capacities, hard carbons (HCs) are a common choice for commercially manufactured anodes in sodium-ion batteries (SIBs). Despite their potential and extensive use, the storage mechanism is still under debate. The non-stoichiometric adsorption mechanism also means that the search for an upper limit for the reversible capacity is ongoing. There is a strong requirement for synthetic anodes that enable a better understanding of the theoretical capacity associated with HC-anodes. We have developed core-shell carbon anodes consisting of a highly porous carbon core and (almost) non-porous shell. Thus, the reversible capacity can be deconvoluted from irreversible capacity losses, arising from the formation of the solid electrolyte interphase (SEI). Moreover, the porosity of the carbon-core can be linked to the reversible capacities gained. A range of microporous activated carbons were coated via an optimized chemical vapour deposition technique.[1][2] These materials were characterised using a range of techniques including powder x-ray diffraction, small angle x-ray diffraction (SAXS), gas physisorption (N2, CO2) measurements and electrochemical characterisation at coin cell level. After coating, the material showed a significant reduction in detectable surface area (up to a factor of 192x) by N2-physisorption. The tailor-made shell allows the stable cycling of a carbon anode vs metallic Na-electrode in coin cells at room temperature. For the best performing material, the reversible capacity increased from 139 ± 2 mAhg-1 to 396 ± 2 mAhg-1 while irreversible capacity is decreased from 636 ± 3 mAhg-1 to 89 ± 3 mAhg-1 (see Figure 1). After initial stabilization, a CE of 99% was achieved. The coating technique was usefully applied to a range of materials. [3] The successful formation of core-shell structures with high capacities enables separation of the storage mechanism from SEI-formation. In turn a proposed calculation to rank the contributions of surface adsorption and pore filling capacity can be confirmed. The materials also create the opportunity to conduct a range of operando experiments (e.g., SAXS) that can shed further light on the sodium storage mechanism. T2 - ECS Montreal 2025 CY - Montreal, Canada DA - 18.05.2025 KW - Electrochemical Energy Materials KW - Negative Electrodes KW - Sodium Ion Batteries PY - 2025 AN - OPUS4-65115 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Sicherheit von NIB und das Potenzial synthetischer Kohlenstoff-Anoden N2 - Nach einer kurzen Einleitung zu kommerziellen Natrium-Ionen-Batterien, deren Zusammensetzung und Sicherheitstest die auch an der BAM untersucht wurden, folgt eine Vorstellung der Forschungsarbeiten des Fachbereich 3.6 im Rahmen des Verbundprojekts Dialysorb. Die Forschungsergebnisse stellen u.a. das Potenzial von synthetischen Anodenmaterialien dar. T2 - Deutsches Batterieforum 2025 CY - Berlin, Germany DA - 21.01.2025 KW - Natrium-Ionen-Batterien KW - Zusammensetzung KW - Potenzial KW - Sicherheit KW - Synthetische Anoden PY - 2025 AN - OPUS4-64904 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauw, Paul T1 - Designing Core-Shell Carbon Structures as High- Capacity Negative Electrodes for Sodium Ion Batteries N2 - Due to abundant raw materials, low costs and promising high reversible specific capacities, hard carbons (HCs) are a common choice for commercially manufactured anodes in sodium-ion batteries (SIBs). Despite their potential and extensive use, the storage mechanism is still under debate. The non-stoichiometric adsorption mechanism also means that the search for an upper limit for the reversible capacity is ongoing. There is a strong requirement for synthetic anodes that enable a better understanding of the theoretical capacity associated with HC-anodes. We have developed core-shell carbon anodes consisting of a highly porous carbon core and (almost) non-porous shell. Thus, the reversible capacity can be deconvoluted from irreversible capacity losses, arising from the formation of the solid electrolyte interphase (SEI). Moreover, the porosity of the carbon-core can be linked to the reversible capacities gained. A range of microporous activated carbons were coated via an optimized chemical vapour deposition technique.[1][2] These materials were characterised using a range of techniques including powder x-ray diffraction, small angle x-ray diffraction (SAXS), gas physisorption (N2, CO2) measurements and electrochemical characterisation at coin cell level. After coating, the material showed a significant reduction in detectable surface area (up to a factor of 192x) by N2-physisorption. The tailor-made shell allows the stable cycling of a carbon anode vs metallic Na-electrode in coin cells at room temperature. For the best performing material, the reversible capacity increased from 139 ± 2 mAhg-1 to 396 ± 2 mAhg-1 while irreversible capacity is decreased from 636 ± 3 mAhg-1 to 89 ± 3 mAhg-1 (see Figure 1). After initial stabilization, a CE of 99% was achieved. The coating technique was usefully applied to a range of materials. [3] The successful formation of core-shell structures with high capacities enables separation of the storage mechanism from SEI-formation. In turn a proposed calculation to rank the contributions of surface adsorption and pore filling capacity can be confirmed. The materials also create the opportunity to conduct a range of operando experiments (e.g., SAXS) that can shed further light on the sodium storage mechanism. T2 - MatSUS Conference Sevilla CY - Sevilla, Spain DA - 03.03.2025 KW - Electrochemical Energy Materials KW - Negative Electrodes KW - Sodium Ion Batteries PY - 2025 AN - OPUS4-65113 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Low, Jian Liang T1 - Elucidating the Intrinsic CO2RR performance at MN4 sites using Morphologically Comparable M-N-Cs N2 - Metal- and nitrogen-doped carbons (M-N-Cs) are a promising class of low-cost electrocatalysts derived from earth-abundant elements for various electrochemical applications including ORR and CO2RR [1,2]. Traditionally, M-N-Cs containing active metals (M = Fe, Co, and Ni) are synthesized through direct pyrolysis of inorganic and organic precursors. However, this process often leads to the undesired formation of inorganic side phases via carbothermal reduction, hindering both the efficient incorporation of active metal and the intrinsic activity comparison among active sites. To overcome these challenges, we developed an active-site imprinting strategy where active metals are introduced post-pyrolysis through ion-exchange [3-5]. In this work, we applied a Mg imprinting strategy to synthesize Co-N-Cs and Ni-N-Cs with comparable morphology and metal dopant concentrations, enabling a more direct comparison of their intrinsic activities. Notably, Ni-N-Cs produced via this method consistently demonstrated superior activity and selectivity compared to isomorphic Co-N-Cs, achieving CO Faraday efficiencies of up to 95% at relatively low overpotentials. Furthermore, the Ni-N-C catalyst exhibited excellent stability at -0.65 VRHE, retaining 92.5% of its current density and 97.6% of its CO selectivity after 100 hours of continuous operation. A distinct advantage of the imprinting strategy lies in the suppression of inorganic side phases, enabling an accurate local structure characterization of the porphyrin-like tetrapyrrolic MN4 coordination structure using Extended X-ray Absorption Fine Structure (EXAFS). The characterization of the tetrapyrrolic NiN4 site is especially puzzling, as density functional theory (DFT) simulations often predict these sites to be inert to both CO2RR and HER. Drawing on recent studies which highlight the crucial role of cations for CO2RR on noble metal catalysts like Cu, Ag and Au [6-7], we performed mechanistic investigations using DFT to extend the relevance of cations to the CO2RR/HER performance at the MN4 sites, and further illustrate the advantage of the pyrrolic N atoms in anchoring them near the active metals. T2 - 4th Conference of the GDCh Division of Chemistry and Energy CY - Duisburg, Germany DA - 09.04.2025 KW - Electrochemical CO2 reduction KW - Active-site imprinting KW - Metal- and Nitrogen-doped Carbon (M-N-C) KW - Single Atom Catalyst PY - 2025 AN - OPUS4-65145 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Low, Jian Liang T1 - Mg-based Imprinting for Assessing Intrinsic Behavior of Co/Ni-N4 sites towards CO2RR N2 - Metal-and nitrogen-doped carbons (MN-Cs) represent a promising class of low cost electrocatalysts derived from nature-abundant elements for various electrochemical processes including CO 2 RR [1, 2]. Traditionally, MN-Cs containing active metals (M= Fe, Co, Ni) are synthesized by direct pyrolysis of inorganic and organic precursors, a process that often results in the undesired formation of inorganic side phases through carbothermal reduction, impeding the effective integration of active metals like Fe, Co and Ni. Furthermore, comparing the intrinsic activities of different MN-Cs can be complicated due to variations in catalyst morphology and active site concentration that arise during the pyrolysis. To address these challenges, we developed an active-site imprinting strategy in which active metals are introduced post-pyrolysis via ion-exchange [3-5]. In this work, we employed the Mg imprinting strategy to produce Co-N-Cs and Ni-N-Cs with comparable morphology and metal dopant concentration. Our approach allows for a more direct comparison of the intrinsic activities that arise from the metal dopant. The Ni-N-Cs derived this way are consistently higher in activity and selectivity than the corresponding Co-N-Cs, exhibiting a CO Faraday efficiency of up to 95% at potentials between-0.5 to-0.8 V RHE. The Ni-NC catalyst maintains high stability at-0.65 V RHE, with 92.5% retention of current density and 97.6% retention of CO selectivity after 100 hours of continuous operation. T2 - The Materials for Sustainable Development Conference (MATSUS) Spring Meeting 2025 CY - Seville, Spain DA - 03.03.2025 KW - Electrochemical CO2 reduction KW - Active-site imprinting KW - Metal- and Nitrogen-doped Carbon (M-N-C) KW - Single Atom Catalyst PY - 2025 AN - OPUS4-65144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Appel, Paul Alexander T1 - Developing Tailor-Made Core-Shell Carbon Negative Electrode Materials for Sodium Ion Batteries N2 - Hard carbons (HCs) are currently one of the most promising anode materials for sodium-ion batteries (SIBs). However, the Na storage mechanism remains controversial, leaving the theoretical limits of carbon anodes unclear. To deconvolute the specific capacity from irreversible capacity losses, resulting from the formation of solid electrolyte interphase (SEI), core-shell carbon materials were synthesized. Based on these core-shell materials, an investigation of the storage mechanism of sodium is possible. T2 - Batterieforum 2025 CY - Berlin, Germany DA - 21.01.2025 KW - Electrochemical Energy Materials KW - Negative Electrodes KW - Sodium Ion Batteries PY - 2025 AN - OPUS4-65110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Okeke, Joseph T1 - In situ and operando imaging, spectroscopy and tomography of batteries N2 - The development of more powerful and more efficient lithium-ion batteries (LIBs) is a key area in battery research, aiming to support the ever-increasing demand for energy storage systems. To better understand the causes and mechanisms of degradation, and thus the diminishing cycling performance and lifetime often observed in LIBs, in operando techniques are essential, because battery chemistry can be monitored non-invasively, in real time. Moreover, there is increasing interest in developing new battery chemistries. Beyond LIBs, sodium ion batteries (NIBs) have gained increasing interest in recent years, as they are a promising candidate to complement LIBs, owing to their improved sustainability and lower cost, while still maintaining high energy density.[1] Initial phases of NIB commercialisation have occurred in the past year. However, for the widespread commercialisation of NIBs, there are still challenges that need to be overcome in developing optimized electrode materials and electrolytes. For the development of such materials and greater understanding of sodium storage mechanisms, solid electrolyte interface (SEI) formation and stability, and degradation processes, in operando methodologies are crucial. Among the techniques available for in operando analysis, nuclear magnetic resonance spectroscopy (NMR) and imaging (MRI) are becoming increasingly used to characterize the chemical composition of battery materials, study the growth and distribution of dendrites, and investigate battery storage and degradation mechanisms. In situ and in operando 1H, 7Li and 23Na NMR and MRI have recently been used to study LIBs and NIBs, identifying chemical changes in Li and Na species respectively, in metallic, quasimetallic and electrolytic environment as well as directly and indirectly studying dendrite formation in both systems.[2-4] The ability of NMR and MRI to probe battery systems across multiple environments can further be complemented by the enhanced spatial resolution of micro-computed X-ray tomography (μ-CT) which can provide insight into battery material microstructure and defect distribution. Here, we report in operando 1H and 7Li NMR and MRI experiments that investigate LIB performance, and the identification of changes in the Li signal during charge cycling, as well as the observation of signals in both 1H and 7Li NMR spectra that we attribute to diminishing battery performance, capacity loss and degradation. Additionally, recent operando methodology are adapted and implemented to study Sn based anodes in NIBs. 23Na spectroscopy is performed to monitor the formation and evolution of peaks assigned to stages of Na insertion into Sn, while 1H MRI is used to indirectly visualize the volume expansion of Sn anodes during charge cycling. Battery operation and degradation is further explored in these NIBs, using μ-CT, where the anode is directly visualized to a higher resolution and the loss of electrolyte in the cell, during cycling is observed T2 - 17th International Conference on Magnetic Resonance Microscopy CY - Singapore DA - 27.08.2023 KW - Sodium ion battery KW - Lithium ion battery KW - NMR KW - MRI KW - Tomography PY - 2023 AN - OPUS4-58421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Winckelmann, Alexander T1 - Investigation of degradation of the aluminum current collector in lithium-ion batteries by glow-discharge optical emission spectroscopy N2 - Lithium-ion batteries (LIBs) are one technology to overcome the challenges of climate and energy crisis. They are widely used in electric vehicles, consumer electronics, or as storage for renewable energy sources. However, despite innovations in batteries' components like cathode and anode materials, separators, and electrolytes, the aging mechanism related to metallic aluminum current collector degradation causes a significant drop in their performance and prevents the durable use of LIBs.[1] Glow-discharge optical emission spectroscopy (GD-OES) is a powerful method for depth-profiling of batteries' electrode materials. This work investigates aging-induced aluminum deposition on commercial lithium cobalt oxide (LCO) batteries' cathodes. The results illustrate the depth-resolved elemental distribution from the cathode surface to the current collector. An accumulation of aluminum is found on the cathode surface by GD-OES, consistent with results from energy-dispersive X-ray spectroscopy (EDX) combined with focused ion beam (FIB) cutting. In comparison to FIB-EDX, GD-OES allows a fast and manageable depth-profiling. Results from different positions on an aged cathode indicate an inhomogeneous aluminum film growth on the surface. The conclusions from these experiments can lead to a better understanding of the degradation of the aluminum current collector, thus leading to higher lifetimes of LIBs. T2 - European Winter Conference on Plasma Spectrochemistry (EWCPS 2023) CY - Ljubljana, Slovenia DA - 29.01.2023 KW - Lithium-ion batteries KW - Aging mechanisms KW - Depth-profiling PY - 2023 AN - OPUS4-56992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sterr, Andrea A1 - Schwarz, Irina T1 - Valorization of Carbon Dioxide by Electrocatalytic Reduction Coupled to Acetogens via Multiple Electron Carriers (Ecat-Acetogens II) N2 - A Bioelectrochemical approach for reducing CO2 to fuels or value-added chemicals allows overcoming the limitations of a pure biochemical or electrochemical approach. A Bioelectrochemical system (BES) for this application has been developed in cooperation with TUM in the first project phase. BAM's contribution to the research focuses on the electrochemical side of the setup, mainly on the development of a suitable CO2RR catalyst for reducing CO2 to CO, which is then consumed by actogenic bacteria to produce further products. Single-metal-atom catalysts in a nitrogen-doped carbon matrix (M-N-Cs) are a promising, sustainable alternative to expensive rare-metal catalysts like Ag and Au. In this work, the first-generation catalyst, a ZIF-8-based Co-N-C is compared to a Mg salt mix templated Ni-N-C. In the new catalysts, the activity for CO2RR as well as the stability during BES operation could be enhanced. T2 - E-Biocat Statusupdate 2025 CY - Karlsruhe, Germany DA - 01.04.2025 KW - CO2RR KW - M-N-Cs KW - Bioelectrochemical System PY - 2025 AN - OPUS4-65143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Castells-Gil, Javier A1 - Zhu, Jinjie A1 - Itskou, Ioanna A1 - Wolpert, Emma H. A1 - Hunter, Robert D. A1 - Tidey, Jeremiah P. A1 - Pedersen, Angus A1 - Solvay, Elisa A1 - Tyrrell, Helen A1 - Petit, Camille A1 - Barrio, Jesús T1 - Impact of N-heterocyclic amine modulators on the structure and thermal conversion of a zeolitic imidazole framework N2 - The zeolitic imidazole framework-8 (ZIF-8) is a crystalline porous material that has been widely employed as template to fabricate porous nitrogen-doped carbons with high microporosity via thermal treatment at high temperatures. The properties of the carbon scaffold are influenced by the pore structure and chemical composition of the parent ZIF. However, the narrow pore size distribution and microporous nature from ZIF-8 often results in low mesopore volume, which is crucial for applications such as energy storage and conversion. Here we show that insertion of N-heterocyclic amines can disrupt the structure of ZIF-8 and dramatically impact the chemical composition and pore structure of the nitrogen-doped carbon frameworks obtained after high-temperature pyrolysis. Melamine and 2,4,6-triaminopyrimidine were chosen to modify the ZIF-8 structure owing to their capability to both coordinate metal ions and establish supramolecular interactions. Employing a wide variety of physical characterization techniques we observed that melamine results in the formation of a mixed-phase material comprising ZIF-8, Zn(Ac)6(Mel)2 and crystallized melamine, while 2,4,6-triaminopyrimidine induces the formation of defects, altering the pore structure. Furthermore, the absence of heterocyclic amine in the ZIF-8 synthesis leads to a new crystalline phase, unreported to date. The thermal conversion of the modified ZIFs at 1000 °C leads to nitrogen-doped carbons bearing Zn moieties with increased surface area, mesopore volume and varying degree of defects compared to ZIF-8 derived carbon. This work therefore highlights both the versatility of heterocyclic amines to modify the structure of framework materials as well as their role in tuning pore structure in nitrogen-doped carbons, paving the way to targeted design of high-performance electrodes for energy storage and conversion. KW - Zeolitic imidazole framework KW - Heterocyclic amine KW - Triaminopyrimidine PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639177 DO - https://doi.org/10.1039/D5TA04831A SN - 2050-7488 SP - 1 EP - 13 PB - Royal Society of Chemistry (RSC) AN - OPUS4-63917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Braga, Daniel S. A1 - Pedersen, Angus A1 - Riyaz, Mohd A1 - Barrio, Jesús A1 - Bagger, Alexander A1 - Neckel, Itamar T. A1 - Mariano, Thiago M. A1 - Winkler, Manuel E. G. A1 - Stephens, Ifan E. L. A1 - Titirici, Maria‐Magdalena A1 - Nagao, Raphael T1 - In situ structural evolution and activity descriptor of atomically dispersed catalysts during nitrate electroreduction N2 - Single‐Atom Catalysts (SAC) have emerged as a promising class of materials for various catalytic applications, including the electrochemical nitrate reduction reaction (eNO3RR) and consequently ammonia production. While the efficiency and selectivity of these materials have been extensively highlighted for the eNO3RR, the in situ evolution to their structure and composition during electrocatalysis is largely unexplored and lacks catalyst design principles. To solve this, we investigated a series of high utilization metal‐nitrogen‐carbon (MNC) SACs (M = Cr, Fe, Co, Ni, and Cu) for eNO3RR. Except for CuNC, which selectively produced nitrite, all catalysts exhibited Faradaic efficiencies (FE) for ammonia exceeding 50%. NiNC demonstrated the highest performance (FE of 78.0 ± 2.9% at −0.4 V versus reversible hydrogen electrode (RHE) at pH 13 and maximum ammonia production rate of 615.7 ± 176.5 µmol·h−1·, corresponding to an energy efficiency of 15.1 ± 1.4% at −0.6 VRHE), followed by CoNC. In situ Synchrotron X‐ray fluorescence (SXRF) mapping at various cathodic potentials (from open circuit potential to 0.0 VRHE and then −0.6 VRHE at 100 mV steps) revealed significant mobility of Ni within the carbon matrix, leading to the formation of metallic clusters from 0.0 VRHE. Similar in situ metal clustering is observed for CoNC. Structure‐activity plots are generated from both MNC literature and results obtained here, finding a clear trend between OH binding energy and turnover frequency, with the high activity of NiNC and CoNC in this work explained by their stronger OH binding in the metallic structure compared to their SAC coordination. This work therefore, reveals the structure‐activity‐stability of MNCs for eNO3RR and provides a simple descriptor for identifying highly active eNO3RR catalysts and their in situ structural evolution. KW - Single atom KW - Nitrate reduction KW - Structure-activity-selectivity KW - In situ PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-640353 DO - https://doi.org/10.1002/advs.202510282 SN - 2198-3844 VL - 12 IS - 39 SP - 1 EP - 14 PB - Wiley-VCH CY - Weinheim AN - OPUS4-64035 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sander, Luise T1 - Linking material and electrode properties to the cell performance of commercially available sodium-ion cells N2 - As the first commercial sodium-ion-batteries (SIBs) are available for purchase, it is possible to investigate material composition. Gaining an insight into the material composition of these SIBs is of interest not only for the classification of possible safety risks and hazards, but also in regard to recycling. Herein we report the preliminary investigations of the chemical and structural composition of first commercial SIB-cells.[1,2] Two different SIB-cell types were compared in terms of electrode size, thickness, loading etc. Furthermore, the composition of the active materials and electrolyte was investigated and compared. Finally, the gained results were linked to the different data sheet performance of the two cell types. T2 - Batterieforum Deutschland 2026 CY - Berlin, Germany DA - 20.01.2026 KW - Electrochemical Energy Storage KW - Battery KW - Sodium-ion-battery KW - EES KW - Energy Storage PY - 2026 AN - OPUS4-65588 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dietzmann, Simon T1 - Between Homogenous and Heterogenous Catalysis: Single-Atom-Catalysts N2 - Catalysis is a very important process in chemistry as it lowers the energy barrier for chemical reactions. This saves energy and/or some reactions are only possible with a catalyst under the desired conditions (temperature and pressure). Catalysts can be roughly categorized depending on the phase they interact with the substrates in homogenous and heterogenous catalysis. T2 - 5. Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Großgeräten (SNI2022) CY - Berlin, Germany DA - 05.09.2022 KW - Single-atom-catalyst KW - Electrochemistry KW - Porous carbons PY - 2022 AN - OPUS4-61989 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dietzmann, Simon T1 - Between Homogenous and Heterogenous Catalysis: Single-Atom-Catalysts N2 - Catalysis is a very important process in chemistry as it lowers the energy barrier for chemical reactions. This saves energy and/or some reactions are only possible with a catalyst under the desired conditions (temperature and pressure). Catalysts can be roughly categorized depending on the phase they interact with the substrates in heterougenous and heterogenous catalyst T2 - RÅC international summer school CY - Varberg, Sweden DA - 14.08.2022 KW - Single-atom-catalyst KW - Electrochemistry KW - Porous carbons PY - 2022 AN - OPUS4-61983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dietzmann, Simon T1 - XAS for structural characterization of atomically dispersed materials N2 - metal and nitrogen enriched carbons (M-N-C) are promising electrocatalysts for small molecule activation. It is proposed that the nitrogen is forming a stabilizing N4-site for the catalytically active metal. This can be proven by XAS measurements to confirm the coordination sphere around the metal. T2 - Bessy User Meeting CY - Online meeting DA - 08.12.2024 KW - Single-atom-catalyst KW - Structural characterization KW - Porous carbons PY - 2022 AN - OPUS4-61994 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauw, Brian Richard T1 - Holistic Experimentation in the HExX-Lab N2 - Through bottom-up, comprehensive digitalisation of all aspects of an experiment, the HEX-lab improves the trustworthiness (traceability, reproducibility, quality) of scientific findings. The five main parts that make up a materials science experiment, i.e. Sample preparation, Measurements, Processing, Analysis, and Interpretation, each have been addressed in thorough and unique ways in this lab, building up a foundation for a wide range of materials science collaborations. Improvements span the spectrum. Hardware developments include new sample environments and stages, such as grazing incidence motion towers, electrochemistry cells and flow-through holders, electronic components such as safety interlocks and multipurpose I/O controllers, and liquid handling systems such as coolant flow cross-over systems. Software developments include: 1) a new comprehensive control system operating on both the RoWaN as well as the MOUSE allowing for full Python control and sequencing of all experimentation, 2) Automated scripts for instrument optimization, sample alignments and measurements, 3) revamped data pipelines and analysis software, standalone or launched as part of operations sequencing dashboards on servers, and 4) meticulously structured archival datafiles, fully documenting sample preparation, measurements, processing and analyses. These allow for holistic databases and dashboards to be constructed to investigate the links between synthesis parameters and resulting morphology. This poster will highlight some of the tools and techniques developed and available in the HEX-lab over the years, from sample environments to overarching experiment and data organisation structures. T2 - Materials Science Core Facility Synergy Forum 2025 CY - Bremen, Germany DA - 26.02.2025 KW - Digitalization KW - Holistic experiments KW - Traceability KW - Data provenance PY - 2025 AN - OPUS4-62675 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wu, Shu-Han T1 - MOF-derived Synthetic Carbon Anode Materials for Sodium-Ion Batteries N2 - Metal-organic frameworks (MOFs), particularly the zeolitic imidazolate framework (ZIF) family, are attractive precursors for advanced energy-storage materials. Upon pyrolysis, ZIFs can be transformed into electrically conductive carbon materials while preserving their original particle morphology, which is crucial for achieving high-performance sodium-ion battery anodes. Despite these advantages, large-scale implementation remains challenging due to the need for synthesis routes that balance performance, cost, and sustainability. The present study addresses these challenges by developing environmentally benign and economically feasible strategies for the scalable production of ZIF-8-derived carbon anodes suitable for industrial applications. T2 - Batterieforum Deutschland 2026 CY - Berlin, Germany DA - 20.01.2026 KW - Sodium-ion battery KW - Negative electrode KW - Metalorganic frameworks PY - 2026 AN - OPUS4-65644 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Petitdemange, Eliot A1 - Zhu, Jinjie A1 - Pedersen, Angus A1 - Parker, Joseph A1 - Balaghi, Esmael A1 - Li, Shaohua A1 - Favero, Silvia A1 - Ignacio Martínez, José A1 - Haigh, Sarah A1 - Titirici, Maria-Magdalena A1 - Fischer, Anna A1 - Barrio, Jesús T1 - High-Yield Synthesis of Fe-NC Electrocatalysts Using Mg2+ Templating and Schiff-Base Porous Organic Polymers N2 - The decoupled synthesis of Fe-NC single-site electrocatalysts mediated by Lewis acids enables high active site density and utilization. However, current approaches often rely on small organic molecules and suffer from low synthesis yields due to the high Lewis acid-to-precursor ratios required to achieve highly porous carbons. Here, a porous organic polymer (POP) based on 2,4,6-Triaminopyrimidine (TAP) is utilized as a carbon-nitrogen-based scaffold for the synthesis of Fe─NC electrocatalysts. By tuning the amounts of MgCl2 ·6H2O used both as porogen and active site templating agent, synthetic yields exceeding 45% are achieved, a significant improvement compared to the 6% yield from the molecular analogue and the highest reported forMg2+ templated systems. Subsequent low-temperature exchange with Fe leads to atomically dispersed FeNx, minimizing Fe aggregation. The resulting materials exhibit high specific surface areas (>1000 m2 g−1) with micro-, meso-, and macropores, which promote mass transport and active site accessibility. Compared to Fe─NC synthesized via direct pyrolysis of Fe-coordinated POP, the decoupled method enables significantly higher catalytic activity in both alkaline and acidic media, and delivers 1 A cm−2 at 0.687 ± 0.004 VRHE in an alkaline gas diffusion electrode, highlighting its potential for practical oxygen reduction devices. KW - Porous Organic Polymers KW - Single Atom KW - Oxygen reduction PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-652618 DO - https://doi.org/10.1002/adfm.202518944 SN - 1616-3028 SP - 1 EP - 15 PB - Wiley-VCH GmbH AN - OPUS4-65261 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hickel, Tilmann A1 - Waske, Anja A1 - Tehranchi, Ali A1 - Bhattacharya, Biswajit A1 - Stawski, Tomasz M. A1 - Fellinger, Tim-Patrick A1 - Mehmood, Asad A1 - Witt, Julia A1 - Ozcan, Ozlem A1 - Guilherme Buzanich, Ana A1 - Kumar, Sourabh A1 - Mishra, Rajesh Kumar A1 - Holzer, Marco A1 - Stucchi de Camargo, Andrea Simone A1 - Agudo Jácome, Leonardo A1 - Manzoni, Anna A1 - Fantin, Andrea A1 - John, Elisabeth A1 - Hodoroaba, Vasile-Dan A1 - Bührig, Sophia A1 - Murugan, Jegatheesan A1 - Marschall, Niklas A1 - George, Janine A1 - Darvishi Kamachali, Reza A1 - Maaß, Robert A1 - Emmerling, Franziska T1 - Chemically complex materials enable sustainable high-performance materials N2 - Chemically complex materials (CCMats) 􀀀 including high-entropy alloys, oxides, and related multi-principal element systems 􀀀 offer a paradigm shift in materials design by leveraging chemical diversity to simultaneously optimize functional, structural, and sustainability criteria. The vastness of the compositional and structural space in CCMats propels the field into an expanding exploratory state. To reconcile functional and structural performance across this immense parameter space remains an open challenge. This Perspective evaluates the opportunities and challenges associated with harnessing chemical complexity across a broad spectrum of applications, such as hydrogen storage, ionic conductors, catalysis, magnetics, dielectrics, semiconductors, optical materials, and multifunctional structural systems. It is delineated how three central design strategies: targeted substitution (SUB), defect engineering (DEF), and diversity management (DIV) enable the reconciliation of high functional performance with long-term structural stability and environmental responsibility. Advances in computational thermodynamics, microstructure simulations, machine learning, and multimodal characterization are accelerating the exploration and optimization of CCMats, while robust data infrastructures and automated synthesis workflows are emerging as essential tools for navigating their complex compositional space. By fostering cross-disciplinary knowledge transfer and embracing data-driven design, CCMats are poised to deliver next-generation materials solutions that address urgent technological, energy, and environmental demands. KW - Chemically complex materials KW - Structural stability KW - Functional performance KW - Design strategies KW - Sustainability PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655598 UR - https://www.sciencedirect.com/science/article/pii/S1359028626000033?via%3Dihub DO - https://doi.org/10.1016/j.cossms.2026.101256 SN - 1359-0286 VL - 42 SP - 1 EP - 26 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-65559 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dietzmann, Simon A1 - Mehmood, Asad A1 - de Oliveira Guilherme Buzanich, Ana A1 - Emmerling, Franziska A1 - Fellinger, Tim-Patrick A1 - Thomas, A. T1 - Characterization of Solid-State Complexes by XAS N2 - Atomically dispersed metal-nitrogen doped carbons (M-N-C) are promising catalysts for the activation of small molecules such as O2 and CO2. These single atom catalysts (SAC) operate at the interface between homogenous and heterogenous catalysts. Currently, many examples of M-N-C are known with good oxygen reduction reaction activity but lacking a controlled synthesis of the specific active sites of the precatalyst. Recently, our group facilitated the synthesis of pure pyrrolic M-N4 sites using Zn ions as imprinters.[1] These amorphous materials obtained by active site imprinting method are characterized at the BAMline (Bessy II) by X-ray absorption spectroscopy (XAS). In-situ/operando measurements will be crucial in future work for a better understanding of the dynamic changes of the active site. T2 - InSynX Workshop 2023 CY - Sao Paulo, Brazil DA - 06.03.2023 KW - Solid-State Complexes PY - 2023 AN - OPUS4-58933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pedersen, Angus A1 - Zhu, Jinjie A1 - Barrio, Jesús A1 - Parker, Joseph A1 - Hunter, Robert D. A1 - Haigh, Sarah J. A1 - Fellinger, Tim-Patrick A1 - Stephens, Ifan E. L. A1 - Titirici, Maria-Magdalena T1 - Contribution of Mg-templated porosity to activity and durability in Fe–N–C O 2 reduction catalysts N2 - Atomically dispersed Fe in N-doped carbon (Fe–N–C) catalysts are leading platinum-group-metal-free candidates for the O2 reduction reaction in proton exchange membrane fuel cells (PEMFCs). Zeolitic imidazolate framework (ZIF-8) derived Fe–N–C present the most promising performance; however, they possess a narrow distribution of small micropores, which limits active site accessibility. Here, to induce hierarchical porosity in Fe–N–C, we report a systematic study on MgCl2·6H2O-templated ZIF-8-derived Fe–N–C catalysts for the O2 reduction reaction. MgCl2·6H2O addition induced complete Zn removal, collapse of the ZIF-8 framework, and formation of large micro- and mesopores, with graphene-like structures. N content was markedly reduced, with conversion from pyridinic to pyrrolic N species. Rotating disc electrode tests showed a progressive increase in O2 reduction activity with MgCl2·6H2O, which is strongly correlated (R2 = 0.98) to the formation of large micropores and small mesopores (1–4 nm). This introduces an indirect structure–activity design principle for Fe–N–Cs. The enhanced Fe–N–C porosity also leads to increased degradation rates under accelerated stress test conditions, which we attributed to the oxidation of disordered carbon domains and active Fe loss. This study highlights a key trade-off between porosity-driven O2 reduction activity and durability in Fe–N–C catalysts. KW - Porosity KW - Single atom KW - Oxygen reduction PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-657549 DO - https://doi.org/10.1039/d5ma01488c SN - 2633-5409 SP - 1 EP - 8 PB - Royal Society of Chemistry (RSC) AN - OPUS4-65754 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -