TY - JOUR A1 - Gong, Mengjun A1 - Mehmood, Asad A1 - de Oliveira Guilherme Buzanich, Ana A1 - Fellinger, Tim-Patrick A1 - Jackson, Colleen A1 - Cui, Junyi A1 - Drazic, Goran A1 - Kucernak, Anthony T1 - Designing Co–N/C Cathode Catalysts with Dense Atomic Cobalt Sites for Enhanced PEMFC Performance N2 - Metal-nitrogen/carbon (M-N/C) catalysts, particularly those incorporating Fe,Co, or Mn, are among the most promising non-platinum group catalysts forthe acidic oxygen reduction reaction (ORR) in fuel cells. This study reports aCo-N/C catalyst featuring high (3 wt%) cobalt content exclusively present asatomic sites. Extended X-ray absorption fine structure analysis confirms atetrapyridinic Co-N4 coordination environment in the optimized (3.0)Co-N/C𝚫catalyst. The high cobalt loading leads to a significant density ofelectrochemically accessible active sites, 3.58 × 10 19 sites g−1 , quantified viathe nitrite stripping method. The catalyst demonstrates excellent ORR activityin a rotating ring-disk electrode setup, achieving a half-wave potential (E 1/2 ) of0.76 V at a low loading of 0.2 mg cm−2 and a mass activity of 3.5 A g−1 at 0.80VRHE . Single-cell hydrogen-oxygen PEMFC tests achieve a peak power densityexceeding 1.3 W cm−2 (iR-corrected). Under hydrogen-air condition, thecatalyst delivers 0.54 A cm−2 at 0.60 V (0.39 W cm−2 ). Despite the intrinsicallyhigher turnover frequency of Fe-based sites, the optimized(3.0)Co-N/C𝚫 catalyst achieves similar fuel cell performance to that of Fe-N/C,highlighting the critical role of site density in overall activity. KW - Fuel cells KW - Single atom catalysts KW - Oxygen reduction reaction KW - Non-precious catalysts PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-644276 DO - https://doi.org/10.1002/advs.202516060 SN - 2198-3844 SP - 1 EP - 11 PB - Wiley VHC-Verlag AN - OPUS4-64427 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - INPR A1 - Rieck, Arielle A1 - Low, Jian Liang A1 - Dietzmann, Simon A1 - Radnik, Jörg A1 - Teimouri, Zahra A1 - Higgins, Drew A1 - Hodoroaba, Vasile-Dan A1 - Mehmood, Asad A1 - Fellinger, Tim-Patrick T1 - Understanding the Activity Trade-Off between Tetrapyrrolic Fe-NCs and Co-NCs in the Alkaline Oxygen Reduction Reaction N2 - A water-free ionothermal synthesis of porous magnesium-imprinted nitrogen-doped carbon (Mg–NC) materials is introduced to prepare a platform material to investigate electrocatalytic structure-performance relations. Atomically dispersed Co- and Fe-NCs isomorphic to the pristine Mg-NCs are prepared by ion-exchange reactions. The current Mg-templating strategy enables relatively high pyrolysis product yields of up to 50 wt% and resultant Fe-NC and Co-NC catalysts contain high and comparable active metal loading of up to 2.52 wt% Fe and 2.29 wt% Co, respectively. A combination of X-ray spectroscopies with DFT studies reveals a tetrapyrrolic structure of the coordination sites, originating from a pyrolytic magnesium template ion reaction within the ionothermal synthesis. Two sets of highly active isomorphic tetrapyrrolic Fe-NCs and Co-NCs are utilized to understand the differences in intrinsic electrocatalytic performance of Co-NCs and Fe-NCs towards the alkaline oxygen reduction reaction (ORR). Despite their superior valence electronic properties to facilitate the initial outer-sphere electron transfer to O2, Co-NCs show significantly lower performance than Fe-NC with comparable loading. Although the generally discussed weaker binding of peroxide intermediates to CoN4 sites compared to FeN4 sites is evident, experimental and theoretical investigation reveal that it is the underlying peroxide oxidation activity that suppresses the oxygen reduction activity of M-NCs. The high peroxide oxidation activity of Co-NCs explains their reduced alkaline ORR relative to Fe-NCs, shedding light on the understated significance of controlling peroxide chemistry for the optimizing cathodic performance. KW - Magnesium Imprinting KW - Tetrapyrrolic Sites KW - Metal- and nitrogen-doped carbon (M-N-C) KW - Oxygen Reduction Reaction (ORR) KW - Nitrogen doped Carbon PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651487 DO - https://doi.org/10.26434/chemrxiv-2025-s59s5 SP - 1 EP - 24 AN - OPUS4-65148 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böttcher, Nils A1 - Sander, Luise A1 - Ulbricht, Alexander A1 - Widjaja, Martinus Putra A1 - Fellinger, Tim-Patrick A1 - Schmidt, Anita A1 - Krug von Nidda, Jonas T1 - Sodium-ion battery research @ BAM (I): investigating the thermal runaway behaviour of commercial sodium-ion battery cells N2 - Commercially available sodium-ion battery (SIB) cells, with energy densities comparable to lithium-ion battery (LIB) cells based on LiFePO4, were investigated regarding their safety behaviour under thermal abuse conditions. Tests were carried out in an inert atmosphere. The SIB-cells went into thermal runaway (TR), intriguingly, even at a rather low state of charge of 30%. The TR-event was coupled with a pronounced jelly roll ejection, challenging the interpretation of the TR-diagrams. These findings highlight the necessity of incorporating SIB-cells into the ongoing safety classification discussions for LIB-cells. KW - Sodium Ion Batteries KW - Thermal Runaway KW - Battery safety PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-647652 DO - https://doi.org/10.1039/d5se00687b SN - 2398-4902 VL - 9 IS - 21 SP - 5832 EP - 5838 PB - Royal Society of Chemistry (RSC) AN - OPUS4-64765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Basics, Challenges and Trends in Electrochemical Energy Storage 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 - Basics, Challenges and Trends in Electrochemical Energy Storage CY - Cottbus, Germany DA - 15.09.2025 KW - Batteries KW - Electrochemistry KW - Energy Materials PY - 2025 AN - OPUS4-64919 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Core-shell type carbon anodes for na-ion batteries 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 - Research Seminar of the Dahn Labs at Dalhousie University CY - Halifax, Canada DA - 27.05.2025 KW - Natrium-Ionen-Batterien KW - Synthetische Anoden KW - Kohlenstoff PY - 2025 AN - OPUS4-64912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fellinger, Tim-Patrick T1 - Commercial State-of-the-Art Sodium-Ion Batteries and Perspectives for the Negative Electrode (Anode) 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). Chinese battery manufacturers marketed the first cells, which are commercially available now. We have purchased and investigated two of these early cells to understand their composition and be able to compare to the state-of-the-art in the scientific community. According to our results and the current literature, all commercial cells utilize carbon-based anodes, with the characteristic sloping charge-discharge profile. In the presentation the results will be discussed in context with safety aspect and space for improvement. The latter aspect will be focused on hard carbon anodes. 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, 4] T2 - Eco-Mat Conference 2025 CY - Istanbul, Türkiye DA - 29.07.2025 KW - Natrium-Ionen-Batterien KW - Synthetische Anoden KW - Kohlenstoff PY - 2025 AN - OPUS4-64908 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 -