TY - JOUR A1 - Dal Molin, E. S. A1 - Henning, L. M. A1 - Müller, J. T. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Bekheet, M. F. A1 - Gurlo, A. A1 - Simon, U. T1 - Robocasting of ordered mesoporous silica‐based monoliths: Rheological, textural, and mechanical characterization N2 - Hierarchically porous, high‐surface‐area silica materials are excellent candidates for multiple applications like catalysis and environmental remediation. Shaping these materials with additive manufacturing (AM) techniques, like robocasting, could enable their use with the benefit of on‐demand, customized shaping and maximizing performance. Herein, ordered mesoporous silica COK‐12 slurries were robocasted into monoliths, containing different ratios of uncalcined COK‐12 and sodium bentonite (0–25 wt.%). The rheology of the mixed slurries is characterized by lower flow indexes (0.69 vs. 0.32) and higher yield stresses (96 vs. 259 Pa) compared to pure COK‐12 ones. Monoliths were printed in woodpile structures and calcined at 600°C. Micro‐CT measurements showed a linear shrinkage of 25% after calcination. Mechanical characterization showed increased uniaxial strength (0.20 ± 0.07 to 1.0 ± 0.3 MPa) with increasing binder/solids ratio from 13 to 25%. The amorphous, mesoporous structure of COK‐12 was retained. The structures exhibited open porosities of 52 ± 4% and showed higher specific mesopore volumes, and increased average mesopore size (6 vs. 8 nm) compared to COK‐12. Small‐angle x‐ray scattering analysis revealed an increased lattice parameter (10.3 vs. 11.0 nm) and reduced wall thickness (3.1 nm vs. 4.1 nm) of the COK‐12 in the monoliths. These properties indicate suitability for their application as porous supports and adsorbents. KW - Industrial and Manufacturing Engineering KW - Additive manufacturing KW - OMS KW - Porous materials KW - Robocasting KW - X-ray scattering KW - MOUSE PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582503 DO - https://doi.org/10.1002/nano.202300109 VL - 4 IS - 11-12 SP - 615 EP - 631 PB - Wiley-VCH GmbH AN - OPUS4-58250 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Henning, Ricky A1 - Sturm, Patrick A1 - Keßler, S. A1 - Gluth, Gregor T1 - Corrosion of hybrid alkaline cements in saline solution simulating evaporite rock – effect of the Portland clinker content N2 - Two hybrid alkaline cements (HAC) based on Portland clinker, ground granulated blast furnace slag (GGBFS), fly ash and sodium sulfate, as well as an alkali-activated GGBFS/fly ash blend and a Portland cement paste were exposed to a saturated saline solution for 70 days. The combined chemical attack of chloride, magnesium and sulfate ions and the associated changes of the phase assemblage of the materials were studied by X-ray diffraction, thermal analysis and spatially resolved X-ray fluorescence spectroscopy. The experimental results revealed dissolution of ettringite, C-N-A-S-H and calcite, and the formation of gypsum, Kuzel's salt and Friedel's salt; thermodynamic modeling indicated the formation of M-S-H. The resistance of the HAC against attack by the saline solution increased with Portland clinker fraction. The capacity of portlandite to maintain pH at values above 10 is found to be a major factor controlling the resistance of HAC against corrosion in the saline solution. KW - Hybrid cements KW - Alkali-activated materials KW - Magnesium chloride KW - Corrosion KW - Salt attack PY - 2023 DO - https://doi.org/10.1016/j.cemconres.2023.107215 SN - 0008-8846 SN - 1873-3948 VL - 172 SP - 1 EP - 14 PB - Elsevier Ltd. AN - OPUS4-57638 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Henning, Ricky A1 - Sturm, Patrick A1 - Kühne, Hans-Carsten A1 - Keßler, S. A1 - Gluth, Gregor T1 - Untersuchungen zur Wärmeentwicklung von hybriden Zementen N2 - Die Hauptfunktion von Verschlussbauwerken für End- und Zwischenlager von radioaktiven Abfällen besteht in der Erhaltung der geologischen Barriere. Vor allem soll ein potenzieller Stofftransport durch eine möglichst geringe Permeabilität des Bauwerks verhindert bzw. auf vernachlässigbare Werte herabgesetzt werden. Die in-situ-Permeabilität des Verschlussbauwerks steht dabei in direktem Zusammenhang mit dessen Poren- und Makrostruktur, welche bei Bauwerken auf Basis von Beton insbesondere durch Schwind-verformungen und durch thermisch induzierte Rissbildung infolge der Reaktionswärmeentwicklung des Bindemittels gestört werden kann. Die Betone müssen daher neben einer hohen chemischen Langzeitstabilität auch eine geringe bzw. langsame Wärmeentwicklung während der Erhärtungsreaktionen aufweisen. Als hybride Zemente werden Mischungen aus Portlandzement, Betonzusatzstoffen und einem alkalischen Aktivator bezeichnet. Dabei können u. a. Alkalisulfate, Alkalicarbonate, Alkalisilicate und Alkalihydroxide als Aktivatoren zum Einsatz kommen. Aufgrund ihrer hohen chemischen Stabilität im salinaren Milieu sind Betone aus solchen Zementen potenziell besonders gut als Verfüllmaterial für End- und Zwischenlager im Steinsalz geeignet. In der vorliegenden Studie wurden daher hybride Zemente hinsichtlich ihrer Wärmeentwicklung in einem isothermen Kalorimeter sowie hinsichtlich Phasenbestand und Festigkeiten untersucht. Hybride Zementleime wurden auf Basis von Portlandklinker, Hüttensandmehl, Flugasche und Natriumsulfat hergestellt und die Zusammensetzungen systematisch variiert, um den Einfluss der Komponenten auf Wärmeentwicklung, Phasenbestand und mechanische Eigenschaften der Leime zu untersuchen; zusätzlich wurden zu Vergleichszwecken ein Zementleim auf Basis der Betonrezeptur M2 sowie eine alkalisch aktivierte Flugasche untersucht. T2 - 2. Tage der Standortauswahl CY - Online meeting DA - 11.02.2021 KW - Hybride Zemente KW - Hydratationswärme KW - Kalorimetrie PY - 2021 SP - 137 EP - 139 AN - OPUS4-52216 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinrich, Thomas A1 - Traulsen, Christoph Hans-Henning A1 - Darlatt, Erik A1 - Richter, S. A1 - Poppenberg, J. A1 - Traulsen, N.L. A1 - Linder, I. A1 - Lippitz, Andreas A1 - Dietrich, Paul A1 - Dib, B. A1 - Unger, Wolfgang A1 - Schalley, C.A. T1 - The versatility of 'Click' reactions at surfaces: Molecular recognition at interfaces N2 - In order to investigate molecular recognition on surfaces, an azide-functionalized monolayer was deposited on gold. The monolayer was characterized by X-ray photoelectron spectroscopy (XPS) and angle-resolved near-edge X-ray absorption fine structure (NEXAFS) experiments and the decomposition of the azide upon irradiation with X-ray beams was investigated. Subsequently, various alkyne-functionalized host and guest molecules were attached to the azide by 1,3-dipolar cycloaddition. These modified surfaces and their host–guest chemistry were analysed by XPS and angle-resolved NEXAFS. The reversibility of guest binding was shown for one example as a proof of principle. KW - 'Click' reaction KW - Azide-terminated surfaces KW - SAMs KW - Host guest molecules KW - Molecular recognition at interfaces PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-306463 DO - https://doi.org/10.1039/C4RA01730G SN - 2046-2069 VL - 4 IS - 34 SP - 17694 EP - 17702 PB - RSC Publishing CY - London AN - OPUS4-30646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Henning, Ricky A1 - Sturm, Patrick A1 - Geddes, D.A. A1 - Keßler, S. A1 - Walkley, B. A1 - Gluth, Gregor T1 - The influence of curing temperature on the strength and phase assemblage of hybrid cements based on GGBFS/FA blends N2 - Hybrid cements are composites made of Portland cement or Portland clinker and one or more supplementary cementitious materials like slag, fly ash or metakaolin, activated with an alkali salt. To date, their hydration mechanism and the phase formation at various temperatures is insufficiently understood, partly due to the large variability of the raw materials used. In the present study, three hybrid cements based on ground granulated blast furnace slag, fly ash, Portland clinker and sodium sulfate, and an alkali-activated slag/fly ash blend were cured at 10 and 21.5°C, and subsequently analyzed by XRD, 27Al MAS NMR, and TGA. The compressive strength of the hybrid cements was higher by up to 27% after 91-day curing at 10°C, compared to curing at 21.5°C. The experimental results as well as thermodynamic modeling indicate that the differences in compressive strength were related to a different phase assemblage, mainly differing amounts of strätlingite and C-N-A-S-H, and the associated differences of the volume of hydration products. While the strätlingite was amorphous to X-rays, it could be identified by 27Al MAS NMR spectroscopy, TGA and thermodynamic modeling. The microstructural properties of the hybrid cements and the alkali-activated slag/fly ash blend as well as the compatibility between thermodynamic modeling results and experimental data as a function of curing temperature and time are discussed. KW - Hybrid cements KW - Strätlingite KW - Thermodynamic modelling KW - Hydration PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-557767 DO - https://doi.org/10.3389/fmats.2022.982568 SN - 2296-8016 VL - 9 SP - 1 EP - 16 PB - Frontiers AN - OPUS4-55776 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Henning, Ricky A1 - Sturm, Patrick A1 - Keßler, S. A1 - Gluth, Gregor ED - Lothenbach, B. ED - Wieland, E. ED - Altmaier, M. T1 - Influence of salt aggregate on the degradation of hybrid alkaline cement (HAC) concretes in magnesium chloride-rich saline solution simulating evaporite rock N2 - Concretes produced from salt aggregate and hybrid alkaline cements, an alkali-activated slag/fly ash blend, or a Portland cement were exposed to a magnesium chloride-rich saline solution ([Mg2+] = 3.6 m, [Cl−] = 8.3 m), representing a solution formed after contact of surface water with evaporite rock (rock salt) in a nuclear waste repository. The hydration and deterioration of the concretes were studied with X-ray diffraction, thermogravimetric analysis, pH mapping and permeability measurements. The results show that calcium silicate hydrate (C-S-H) or sodium-substituted calcium aluminium silicate hydrate (C-N-A-S-H) and Friedel's salt were the major reaction products in the concretes prior to exposure to the saline solution. During exposure to the saline solution, increasing amounts of C-S-H/C-N-A-S-H dissolved, and gypsum and a secondary AFm phase formed. The durability of the concretes improved with increasing amounts of Portland clinker in the cements, due to the associated differences in permeability and chemical resistance. Nevertheless, a massive increase of permeability occurred for all concretes, likely caused by crack formation due to the formation of gypsum from anhydrite in the salt aggregate. Thus, the behavior of the concretes differed from, and was more complex than, the behavior of plain cement pastes. T2 - Joint 6th International Workshop on Mechanisms and Modelling of Waste/Cement Interactions (JCCW 2023) CY - Prague, Czech Republic DA - 20.11.2023 KW - Nuclear waste repository KW - Evaporite rock KW - Magnesium chloride brine KW - Concrete KW - Hybrid alkaline cement PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-599928 DO - https://doi.org/10.1016/j.apgeochem.2024.106027 SN - 0883-2927 SN - 1872-9134 VL - 168 SP - 1 EP - 14 PB - Elsevier AN - OPUS4-59992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Al-Falahat, A. A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Kupsch, Andreas A1 - Woracek, R. A1 - Alrwashdeh, S. A1 - Manke, I. T1 - Investigation of detector backlighting and other effects in neutron darkfield images N2 - Neutron imaging can provide unique contrast mechanisms. In order to yield reliable and reproducible attenuation coefficients for quantification, one needs to fully understand and characterize the experimental set-up. One effect that has been largely overlooked in scintillator-camera based neutron imaging systems is the backlight scattering or back illumination in the detection system which can significantly affect the quantification of attenuation coefficients and lead to severe errors and image artifacts. Herein, backlighting is investigated by varying the illuminated detector area and the magnitude of the attenuation. The attenuation coefficient of multiple metal plates was determined by polychromatic neutrons bu the CONRAD V7 instrument. The strength of the back illumination strongly depends upon the sample absorption. While it is relatively moderate (a few percent) for weak absorbing samples, it can be severe when the sample is a strong absorber or thick. KW - Attenuation coefficient KW - Neutron imaging KW - Neutron scattering KW - Polycromatic neutrons KW - Scintillator PY - 2024 SN - 1073-9149 DO - https://doi.org/10.1080/10739149.2024.2380772 SP - 1 EP - 11 PB - Taylor & Francis AN - OPUS4-60752 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Johannesmann, S. A1 - Henning, B. A1 - Prager, Jens T1 - Analysis of Lamb wave mode repulsion and its implications to the characterisation of adhesive bonding strength N2 - Lamb waves are widely used for non-destructive evaluation of material parameters as well as for detection of defects. Another application of Lamb waves is quality control of adhesive joints. Researchers are currently investigating shear horizontal and zero-group velocity modes for characterisation of the adhesive bonding strength. In a new approach, Lamb wave mode repulsion is used to obtain the coupling strength between different layers to characterise the adhesive bonding strength. The modes of the individual layers become coupled in the multilayered systems forming particular regions, the so-called mode repulsion regions. This study investigates these modes and their interaction in two-layered plate-like structures with varying coupling strength both numerically, with the Scaled Boundary FEM, and experimentally T2 - International Congress on Ultrasonics CY - Bruges, Belgium DA - 03.09.2019 KW - Lamb waves KW - Multi-layered system KW - Adhesive joint KW - Mechanical strength KW - Scaled Boundary FEM PY - 2019 SP - 1 EP - 4 AN - OPUS4-48911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Peruzzi, N. A1 - Galli, S. A1 - Helmholz, H. A1 - Kardjilov, N. A1 - Krüger, D. A1 - Markötter, Henning A1 - Moosmann, J. A1 - Orlov, D. A1 - Prgomet, Z. A1 - Willumeit-Römer, R. A1 - Wennerberg, A. A1 - Bech, M. T1 - Multimodal ex vivo methods reveal that Gd-rich corrosion byproducts remain at the implant site of biodegradable Mg-Gd screws N2 - Extensive research is being conducted on magnesium (Mg) alloys for bone implant manufacturing, due to their biocompatibility, biodegradability and mechanical properties. Gadolinium (Gd) is among the most promising alloying elements for property control in Mg alloy implants; however, its toxicity is contro- versial. Investigating Gd behavior during implant corrosion is thus of utmost importance. In this study, we analyzed the degradation byproducts at the implant site of biodegradable Mg-5Gd and Mg-10Gd implants after 12 weeks healing time, using a combination of different imaging techniques: histology, energy-dispersive x-ray spectroscopy (EDX), x-ray microcomputed tomography (μCT) and neutron μCT. The main finding has been that, at the healing time in exam, the corrosion appears to have involved only the Mg component, which has been substituted by calcium and phosphorus, while the Gd remains localized at the implant site. This was observed in 2D by means of EDX maps and extended to 3D with a novel application of neutron tomography. X-ray fluorescence analysis of the main excretory organs also did not reveal any measurable accumulation of Gd, further reinforcing the conclusion that very limited or no removal at all of Gd-alloy happened during degradation. KW - Magnesium-gadolinium alloy KW - Biodegradable implant KW - Multimodal analysis KW - Energy-dispersive x-ray spectroscopy KW - Micro-computed tomography PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-535910 DO - https://doi.org/10.1016/j.actbio.2021.09.047 SN - 1742-7061 SP - 1 EP - 10 PB - Elsevier Ltd. AN - OPUS4-53591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Van Tran, K. A1 - Woracek, R. A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Abou-Ras, D. A1 - Puplampu, S. A1 - Förster, C. A1 - Penumadu, D. A1 - Dahlberg, C. F. O. A1 - Banhart, J. A1 - Manke, I. T1 - Torsion of a rectangular bar: Complex phase distribution in 304L steel revealed by neutron tomography N2 - Metastable austenitic stainless steel (304L) samples with a rectangular cross-section were plastically deformed in torsion during which they experienced multiaxial stresses that led to a complex martensitic phase distribution owing to the transformation induced plasticity effect. A three-dimensional characterization of the phase distributions in these cm-sized samples was carried out by wavelength-selective neutron tomography. It was found that quantitatively correct results are obtained as long as the samples do not exhibit any considerable preferential grain orientation. Optical microscopy, electron backscatter diffraction, and finite element modeling were used to verify and explain the results obtained by neutron tomography. Altogether, neutron tomography was shown to extend the range of microstructure characterization methods towards the meso- and macroscale. KW - Neutron tomography KW - Phase distribution KW - Rectangular cross-section KW - Torsion KW - Geometrical effect PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-561649 DO - https://doi.org/10.1016/j.matdes.2022.111037 SN - 0264-1275 VL - 222 SP - 111037 PB - Elsevier Ltd. AN - OPUS4-56164 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tran, K. V. A1 - Woracek, R. A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Abou-Ras, D. A1 - Puplampu, S. A1 - Förster, C. A1 - Penumadu, D. A1 - Dahlberg, C. F. O. A1 - Banhart, J. A1 - Manke, I. T1 - Torsion of a rectangular bar: Complex phase distribution in 304L steel revealed by neutron tomography N2 - Metastable austenitic stainless steel (304L) samples with a rectangular cross-section were plastically deformed in torsion during which they experienced multiaxial stresses that led to a complex martensitic phase distribution owing to the transformation induced plasticity effect. A three-dimensional characterization of the phase distributions in these cm-sized samples was carried out by wavelength-selective neutron tomography. It was found that quantitatively correct results are obtained as long as the samples do not exhibit any considerable preferential grain orientation. Optical microscopy, electron backscatter diffraction, and finite element modeling were used to verify and explain the results obtained by neutron tomography. Altogether, neutron tomography was shown to extend the range of microstructure characterization methods towards the meso- and macroscale. KW - Neutron tomography KW - Phase distribution KW - Rectangular cross-section KW - Torsion KW - Geometrical effect PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569101 DO - https://doi.org/10.1016/j.matdes.2022.111037 VL - 222 SP - 1 EP - 13 PB - Elsevier Ltd. AN - OPUS4-56910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Trogadas, P. A1 - Cho, J. I. S. A1 - Rasha, L. A1 - Lu, X. A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Manke, I. A1 - Shearing, P. R. A1 - Brett, D. J. L. A1 - Coppens, M. O. T1 - A nature-inspired solution for water management in flow fields for electrochemical devices N2 - A systematic, nature-inspired chemical engineering approach is employed to solve the issue of flooding in electrochemical devices. The mechanism of passive water transport utilized by lizards living in arid environments is leveraged to design flow-fields with a microchannel structure on their surface, through which capillary pressure rapidly removes the water generated in the electrochemical device. This water management strategy is implemented in proton exchange membrane fuel cells (PEMFCs) with a lunginspired flow-field, which ensures uniform distribution of reactants across the catalyst layer. Jointly, this nature-inspired approach results in flood-free, stable operation at 100% RH and a B60% increase in current (B1.9 A cm-2) and peak power density (B650 mW cm−2) compared to current PEMFCs with a flood-prone, serpentine flow-field (B0.8 A cm-2 and 280 mW cm-2, respectively). This significant advance allows for PEMFC operation at fully humidified conditions. KW - Neutron imaging KW - X-ray tomography KW - Fuel cell PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596662 DO - https://doi.org/10.1039/d3ee03666a VL - 17 SP - 2007 EP - 2017 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59666 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zheng, Y. A1 - Zhang, S. A1 - Ma, J. A1 - Sun, F. A1 - Osenberg, M. A1 - Hilger, A. A1 - Markötter, Henning A1 - Wilde, F. A1 - Manke, I. A1 - Hu, Z. A1 - Cui, G. T1 - Codependent failure mechanisms between cathode and anode in solid state lithium metal batteries: mediated by uneven ion flux N2 - An in-depth understanding of the degradation mechanisms is a prerequisite for developing the nextgeneration all solid-state lithium metal battery (ASSLMB) technology. Herein, synchrotron X-ray computed tomography (SXCT) together with other probing tools and simulation method were employed to rediscover the decaying mechanisms of LiNi0.8Co0.1Mn0.1O2 (NCM)|Li6PS5Cl (LPSCl)|Li ASSLMB. It reveals that the detachment and isolation of NCM particles cause the current focusing on the remaining active regions of cathode. The extent of Li stripping and the likelihood of Li+ plating into LPSCl facing the active NCM particles becomes higher. Besides, the homogeneity of Li stripping/plating is improved by homogenizing the electrochemical reactions at the cathode side by LiZr2(PO4)3 (LZP) coating. These results suggest a codependent failure mechanism between cathode and anode that is mediated by uneven Li ion flux. This work contributes to establish a holistic understanding of the degradation mechanisms in ASSLMBs and opens new opportunities for their further optimization and evelopment. KW - Current density distribution KW - Lithium ion flux KW - Solid-state lithium metal batteries KW - Codependent failure mechanism KW - Cathode deactivation PY - 2023 DO - https://doi.org/10.1016/j.scib.2023.03.021 SN - 2095-9273 VL - 68 IS - 8 SP - 813 EP - 825 PB - Elsevier B.V. AN - OPUS4-57309 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, J. A1 - Zhang, S. A1 - Yao, J. A1 - Guo, Z. A1 - Osenberg, M. A1 - Hilger, A. A1 - Markötter, Henning A1 - Wilde, F. A1 - Manke, I. A1 - Zhang, X. A1 - Sun, F. A1 - Cui, G. T1 - Synergistic Effect of CO2 in Accelerating the Galvanic Corrosion of Lithium/Sodium Anodes in Alkali Metal−Carbon Dioxide Batteries N2 - Rechargeable alkali metal−CO2 batteries, which combine high theoretical energy density and environmentally friendly CO2 fixation ability, have attracted worldwide attention. Unfortunately, their electrochemical performances are usually inferior for practical applications. Aiming to reveal the underlying causes, a combinatorial usage of advanced nondestructive and postmortem characterization tools is used to intensively study the failure mechanisms of Li/Na−CO2 batteries. It is found that a porous interphase layer is formed between the separator and the Li/Na anode during the overvoltage rising and battery performance decaying process. A series of control experiments are designed to identify the underlying mechanisms dictating the observed morphological evolution of Li/Na anodes, and it is found that the CO2 synergist facilitates Li/Na chemical corrosion, the process of which is further promoted by the unwanted galvanic corrosion and the electrochemical cycling conditions. A detailed compositional analysis reveals that the as-formed interphase layers under different conditions are similar in species, with the main differences being their inconsistent quantity. Theoretical calculation results not only suggest an inherent intermolecular affinity between the CO2 and the electrolyte solvent but also provide the most thermodynamically favored CO2 reaction pathways. Based on these results, important implications for the further development of rechargeable alkali metal−CO2 batteries are discussed. The current discoveries not only fundamentally enrich our knowledge of the failure mechanisms of rechargeable alkali metal−CO2 batteries but also provide mechanistic directions for protecting metal anodes to build high-reversible alkali metal−CO2 batteries. KW - Alkali metal batteries KW - Synchrotron X-ray computed tomography KW - Lithium/sodium−carbon dioxide batteries KW - Battery failure mechanisms KW - Alkali metal anodes PY - 2024 DO - https://doi.org/10.1021/acsnano.4c02329 SP - 1 EP - 16 AN - OPUS4-59922 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wu, Y. A1 - Lu, X. A1 - Cho, J.I.S. A1 - Rasha, L. A1 - Whiteley, M. A1 - Neville, T. P. A1 - Ziesche, R. A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Manke, I. A1 - Zhang, X. A1 - Shearing, P. R. A1 - Brett, D. J. L. T1 - Multi-length scale characterization of compression on metal foam flow-field based fuel cells using X-ray computed tomography and neutron radiography N2 - The mechanical compression of metal foam flow-field based polymer electrolyte fuel cells (PEFCs) is critical in determining the interfacial contact resistance with gas diffusion layers (GDLs), reactant flow and water management. The distinct scale between the pore structure of metal foams and the entire flow-field warrant a multilength scale characterization that combines ex-situ tests of compressed metal foam samples and in-operando analysis of operating PEFCs using X-ray computed tomography (CT) and neutron radiography. An optimal ‘medium’ compression was found to deliver a peak power density of 853 mW/cm². The X-ray CT data indicates that the compression process significantly decreases the mean pore size and narrows the pore size distribution of metal foams. Simulation results suggest compressing metal foam increases the pressure drop and gas velocity, improving the convective liquid water removal. This is in agreement with the neutron imaging results that demonstrates an increase in the mass of accumulated liquid water with minimum compression compared to the medium and maximum compression cases. The results show that a balance between Ohmic resistance, water removal capacity and parasitic power is imperative for the optimal performance of metal foam based PEFCs. KW - Fuel cell KW - Compression effect KW - Metal foam microstructure KW - Neutron radiography KW - X-ray CT PY - 2021 DO - https://doi.org/10.1016/j.enconman.2020.113785 VL - 239 SP - 10 EP - 113785 PB - Elsevier Ltd. AN - OPUS4-53842 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -