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1. Li-O2 cell scale energy densities

Author

Prehal, Christian and Freunberger, Stefan A.

Subjects
Physics - Applied Physics
Abstract

In a recent issue of Joule, Dongmin Im and coworkers from Samsung in South Korea describe a prototype lithium-O2 battery that reaches 700 Wh kg-1 and 600 Wh L-1 on cell level. They cut all components to the minimum to reach this value. Difficulties to fill the pores with discharge product and inhomogeneous cell utilization turn out to limit the achievable energy. The work underlines the importance to report performance with respect to full cell weight and volume.

Published
2019
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6. Operando Scanning Small-/Wide-Angle X-ray Scattering for Polymer Electrolyte Fuel Cells: Investigation of Catalyst Layer Saturation and Membrane Hydration– Capabilities and Challenges

Author

Aliyah, Kinanti, primary, Appel, Christian, additional, Lazaridis, Timon, additional, Prehal, Christian, additional, Ammann, Martin, additional, Xu, Linfeng, additional, Guizar-Sicairos, Manuel, additional, Gubler, Lorenz, additional, Büchi, Felix N., additional, and Eller, Jens, additional

Published
2024
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8. Nanoporous activated carbon cloth as a versatile material for hydrogen adsorption, selective gas separation and electrochemical energy storage

Author

Kostoglou, Nikolaos, Koczwara, Christian, Prehal, Christian, Terziyska, Velislava, Babic, Biljana, Matovic, Branko, Constantinides, Georgios, Tampaxis, Christos, Charalambopoulou, Georgia, Steriotis, Theodore, Hinder, Steve, Baker, Mark, Polychronopoulou, Kyriaki, Doumanidis, Charalabos, Paris, Oskar, Mitterer, Christian, and Rebholz, Claus

Published
2017
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11. Are SAXS and SANS suitable to extract information on the role of water for electric-double-layer formation at the carbon–aqueous-electrolyte interface?

Author

Seyffertitz, Malina, Stock, Sebastian, Rauscher, Max Valentin, Prehal, Christian, Haas, Sylvio, Porcar, Lionel, and Paris, Oskar

Abstract

This study reports on the applicability of X-ray transmission (XRT), small- and wide-angle X-ray scattering (SAXS/WAXS) and small-angle neutron scattering (SANS) for investigating fundamental processes taking place in the working electrode of an electric double-layer capacitor with 1 M RbBr aqueous electrolyte at different applied potentials. XRT and incoherent neutron scattering are employed to determine global ion- and water-concentration changes and associated charge-balancing mechanisms. We showcase the suitability of SAXS and SANS, respectively, to get complementary information on local ion and solvent rearrangement in nanoconfinement, but also underscore the limitations of simple qualitative models, asking for more quantitative descriptions of water–water and ion–water interactions via detailed atomistic modelling approaches. [ABSTRACT FROM AUTHOR]

Published
2024
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12. Quantification of PEFC Catalyst Layer Saturation via In Silico, Ex Situ, and In Situ Small-Angle X-ray Scattering

Author

Aliyah, Kinanti, primary, Prehal, Christian, additional, Diercks, Justus S., additional, Diklić, Nataša, additional, Xu, Linfeng, additional, Ünsal, Seçil, additional, Appel, Christian, additional, Pauw, Brian R., additional, Smales, Glen J., additional, Guizar-Sicairos, Manuel, additional, Herranz, Juan, additional, Gubler, Lorenz, additional, Büchi, Felix N., additional, and Eller, Jens, additional

Published
2023
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19. Exclusive Solution Discharge in Li–O2 Batteries?

Author

Prehal, Christian, Mondal, Soumyadip, Lovicar, Ludek, and Freunberger, Stefan A.

Abstract

Capacity, rate performance, and cycle life of aprotic Li-O2 batteries critically depend on reversible electrodeposition of Li2O2. Current understanding states surface-adsorbed versus solvated LiO2 controls Li2O2 growth as surface film or as large particles. Herein, we show that Li2O2 forms across a wide range of electrolytes, carbons, and current densities as particles via solution-mediated LiO2 disproportionation, bringing into question the prevalence of any surface growth under practical conditions. We describe a unified O2 reduction mechanism, which can explain all found capacity relations and Li2O2 morphologies with exclusive solution discharge. Determining particle morphology and achievable capacities are species mobilities, true areal rate, and the degree of LiO2 association in solution. Capacity is conclusively limited by mass transport through the tortuous Li2O2 rather than electron transport through a passivating Li2O2 film. Provided that species mobilities and surface growth are high, high capacities are also achieved with weakly solvating electrolytes, which were previously considered prototypical for low capacity via surface growth., ACS Energy Letters, 7 (9), ISSN:2380-8195

Published
2022

25. ChemPlusChem / A Facile One-Pot Synthesis of Hierarchically Organized Carbon/TiO2 Monoliths with Ordered Mesopores

Author

Schoiber, Jürgen, Christian, Koczwara, Rumswinkel, Simon, Whitmore, Lawrence, Prehal, Christian, Putz, Florian, Elsaesser, Michael S., Paris, Oskar, and Hüsing, Nicola

Abstract

Sol–gel processing combined with soft templating and gelation-induced phase separation is very sensitive to the precursor sol composition. In this work we present a straightforward synthesis towards hierarchically structured, macroporous carbon/titania monoliths with ordered mesopores derived from resorcinol/formaldehyde monoliths and a glycolated titanium precursor. We demonstrate the influence of various reaction solvents, where diol-based media and the proportion of the catalyst seem to be essential in controlling spinodal decomposition, obtaining similar monolithic structures under different synthesis conditions. Based on these observations, we further homogeneously incorporated TiO2 into the carbon structure by an in situ synthesis approach, obtaining structural features similar to pure carbon materials with surface areas of about 400 m2 g−1, periodically arranged mesopores with a mean distance of 10–11 nm and cellular macroporosity.

Published
2021
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29. Current status and future perspectives of lithium metal batteries

Author

Varzi, Alberto, primary, Thanner, Katharina, additional, Scipioni, Roberto, additional, Di Lecce, Daniele, additional, Hassoun, Jusef, additional, Dörfler, Susanne, additional, Altheus, Holger, additional, Kaskel, Stefan, additional, Prehal, Christian, additional, and Freunberger, Stefan A., additional

Published
2020
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33. Willow Bark for Sustainable Energy Storage Systems

Author

Hobisch, Mathias Andreas, primary, Phiri, Josphat, additional, Dou, Jinze, additional, Gane, Patrick, additional, Vuorinen, Tapani, additional, Bauer, Wolfgang, additional, Prehal, Christian, additional, Maloney, Thaddeus, additional, and Spirk, Stefan, additional

Published
2020
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40. Towards Real-Time Ion-Specific Structural Sensitivity in Nanoporous Carbon Electrodes Using In Situ Anomalous Small-Angle X-ray Scattering

Author

Koczwara, Christian, Prehal, Christian, Haas, Sylvio, Boesecke, Peter, Huesing, Nicola, and Paris, Oskar

Subjects
ddc:600
Abstract

ACS applied materials & interfaces 11(45), 42214 - 42220 (2019). doi:10.1021/acsami.9b14242, Current in situ techniques to study ion charge storage and electrical double-layer formation in nanoporous electrodes are either chemically sensitive to element-specific concentration changes or structurally sensitive to rearrangements of ions and solvent molecules; but rarely can they cover both. Here we introduce in situ anomalous small-angle X-ray scattering (ASAXS) as a unique method to extract both real-time structural and ion-specific chemical information from one single experiment. Using a 1 M RbBr aqueous electrolyte and a hierarchical micro- and mesoporous carbon electrode, we identify different charging mechanisms for positive and negative applied potentials. We are able not only to track the global concentration change of each ion species individually, but also to observe their individual local rearrangement within the pore space., Published by Soc., Washington, DC

Published
2019
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44. Singlet oxygen from cation driven superoxide disproportionation and consequences for aprotic metal–O2 batteries

Author

Mourad, Eléonore, primary, Petit, Yann K., additional, Spezia, Riccardo, additional, Samojlov, Aleksej, additional, Summa, Francesco F., additional, Prehal, Christian, additional, Leypold, Christian, additional, Mahne, Nika, additional, Slugovc, Christian, additional, Fontaine, Olivier, additional, Brutti, Sergio, additional, and Freunberger, Stefan A., additional

Published
2019
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45. In situ small-angle X-ray scattering reveals solution phase discharge of Li-O2 batteries with weakly solvating electrolytes.

Author

Prehal, Christian, Samojlov, Aleksej, Nachtnebel, Manfred, Lovicar, Ludek, Kriechbaum, Manfred, Amenitsch, Heinz, and Freunberger, Stefan A.

Subjects
*SMALL-angle X-ray scattering, *ELECTROLYTES, *X-ray scattering, *CONFORMAL coatings, *LITHIUM industry, *CHARGE exchange, *LABOR mobility
Abstract

Electrodepositing insulating lithium peroxide (Li2O2) is the key process during discharge of aprotic Li-O2 batteries and determines rate, capacity, and reversibility. Current understanding states that the partition between surface adsorbed and dissolved lithium superoxide governs whether Li2O2 grows as a conformal surface film or larger particles, leading to low or high capacities, respectively. However, better understanding governing factors for Li2O2 packing density and capacity requires structural sensitive in situ metrologies. Here, we establish in situ small- and wide-angle X-ray scattering (SAXS/WAXS) as a suitable method to record the Li2O2 phase evolution with atomic to submicrometer resolution during cycling a custom-built in situ Li-O2 cell. Combined with sophisticated data analysis, SAXS allows retrieving rich quantitative structural information from complex multiphase systems. Surprisingly, we find that features are absent that would point at a Li2O2 surface film formed via two consecutive electron transfers, even in poorly solvating electrolytes thought to be prototypical for surface growth. All scattering data can be modeled by stacks of thin Li2O2 platelets potentially forming large toroidal particles. Li2O2 solution growth is further justified by rotating ring-disk electrode measurements and electron microscopy. Higher discharge overpotentials lead to smaller Li2O2 particles, but there is no transition to an electronically passivating, conformal Li2O2 coating. Hence, mass transport of reactive species rather than electronic transport through a Li2O2 film limits the discharge capacity. Provided that species mobilities and carbon surface areas are high, this allows for high discharge capacities even in weakly solvating electrolytes. The currently accepted Li-O2 reaction mechanism ought to be reconsidered. [ABSTRACT FROM AUTHOR]

Published
2021
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46. A Facile One‐Pot Synthesis of Hierarchically Organized Carbon/TiO2 Monoliths with Ordered Mesopores.

Author

Schoiber, Jürgen, Koczwara, Christian, Rumswinkel, Simon, Whitmore, Lawrence, Prehal, Christian, Putz, Florian, Elsaesser, Michael S., Paris, Oskar, and Hüsing, Nicola

Subjects
MESOPORES, SURFACES (Technology), SOL-gel processes, GELATION, MESOPOROUS materials, PHASE separation, SURFACE area, MACROPOROUS polymers
Abstract

Sol–gel processing combined with soft templating and gelation‐induced phase separation is very sensitive to the precursor sol composition. In this work we present a straightforward synthesis towards hierarchically structured, macroporous carbon/titania monoliths with ordered mesopores derived from resorcinol/formaldehyde monoliths and a glycolated titanium precursor. We demonstrate the influence of various reaction solvents, where diol‐based media and the proportion of the catalyst seem to be essential in controlling spinodal decomposition, obtaining similar monolithic structures under different synthesis conditions. Based on these observations, we further homogeneously incorporated TiO2 into the carbon structure by an in situ synthesis approach, obtaining structural features similar to pure carbon materials with surface areas of about 400 m2 g−1, periodically arranged mesopores with a mean distance of 10–11 nm and cellular macroporosity. [ABSTRACT FROM AUTHOR]

Published
2021
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