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DOI	10.1073/pnas.2021893118
	In situ small-angle X-ray scattering reveals solution phase discharge of Li-O2 batteries with weakly solvating electrolytes
	Prehal C.; Samojlov A.; Nachtnebel M.; Lovicar L.; Kriechbaum M.; Amenitsch H.; Freunberger S.A.
发表日期	2021
ISSN	00278424
卷号	118 期号:14
英文摘要	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. © 2021 National Academy of Sciences. All rights reserved.
英文关键词	Disproportionation; Li-air battery; Oxygen reduction; Small-angle X-ray scattering
语种	英语
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/180006
作者单位	Institute for Chemistry and Technology of Materials, Graz University of Technology, Graz, 8010, Austria; Department of Information Technology and Electrical Engineering, ETH Zürich, Zürich, 8092, Switzerland; Institute of Electron Microscopy and Nanoanalysis, Graz Centre for Electron Microscopy (FELMI-ZFE), Graz University of Technology, Graz, 8010, Austria; Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria; Institute of Inorganic Chemistry, Graz University of Technology, Graz, 8010, Austria
推荐引用方式 GB/T 7714	Prehal C.,Samojlov A.,Nachtnebel M.,et al. In situ small-angle X-ray scattering reveals solution phase discharge of Li-O2 batteries with weakly solvating electrolytes[J],2021,118(14).
APA	Prehal C..,Samojlov A..,Nachtnebel M..,Lovicar L..,Kriechbaum M..,...&Freunberger S.A..(2021).In situ small-angle X-ray scattering reveals solution phase discharge of Li-O2 batteries with weakly solvating electrolytes.Proceedings of the National Academy of Sciences of the United States of America,118(14).
MLA	Prehal C.,et al."In situ small-angle X-ray scattering reveals solution phase discharge of Li-O2 batteries with weakly solvating electrolytes".Proceedings of the National Academy of Sciences of the United States of America 118.14(2021).