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Poor Stability of Li 2 CO 3 in the Solid Electrolyte Interphase of a Lithium‐Metal Anode Revealed by Cryo‐Electron Microscopy
Author(s) -
Han Bing,
Zhang Zhen,
Zou Yucheng,
Xu Kang,
Xu Guiyin,
Wang Hong,
Meng Hong,
Deng Yonghong,
Li Ju,
Gu Meng
Publication year - 2021
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202100404
Subject(s) - electrolyte , materials science , lithium (medication) , lithium carbonate , amorphous solid , chemical engineering , inorganic chemistry , anode , transmission electron microscopy , electrode , nanotechnology , ionic bonding , chemistry , ion , crystallography , organic chemistry , medicine , engineering , endocrinology
The solid electrolyte interphase (SEI) dictates the cycling stability of lithium‐metal batteries. Here, direct atomic imaging of the SEI's phase components and their spatial arrangement is achieved, using ultralow‐dosage cryogenic transmission electron microscopy. The results show that, surprisingly, a lot of the deposited Li metal has amorphous atomic structure, likely due to carbon and oxygen impurities, and that crystalline lithium carbonate is not stable and readily decomposes when contacting the lithium metal. Lithium carbonate distributed in the outer SEI also continuously reacts with the electrolyte to produce gas, resulting in a dynamically evolving and porous SEI. Sulfur‐containing additives cause the SEI to preferentially generate Li 2 SO 4 and overlithiated lithium sulfate and lithium oxide, which encapsulate lithium carbonate in the middle, limiting SEI thickening and enhancing battery life by a factor of ten. The spatial mapping of the SEI gradient amorphous (polymeric → inorganic → metallic) and crystalline phase components provides guidance for designing electrolyte additives.