Mechanistic insights into the processes of the initial stage of electrolyte degradation in lithium metal batteries

The lithium (Li) metal batteries (LMBs) are considered one of the most promising next-generation batter-ies due to its extremely high theoretical specific capacity. However, there are a couple of issues, e.g., the serious side reactions that occurred at the solid-liquid interface between the electrolyte and Li metal an-ode, hindering the broad commercialization of LMBs. Thus, a comprehensive understanding of the mech-anisms underlying the decomposition of electrolytes is crucial to the design of LMBs. Herein, we utilize density functional theory simulations to explore the decomposition mechanism of electrolytes. The most commonly used ether electrolyte solvents, i.e., 1,2-dimethoxyethane (DME) and 1,3-dioxalane (DOL), based on suitable lithium salts, namely bis(trifluoromethanesulfonyl)imide (LiTFSI), are chosen to model the ac-tual situations. We explicitly demonstrate that an electron-rich environment near the interface accelerates the decomposition of electrolytes. For ether electrolytes, we show that the LiTFSI degradation path is de-pending on the ratio of DOL to DME. In addition, the solvation structures of lithium-ion undergo a series of transformations upon electrolyte degradation, becoming thermodynamically more favorable and having a higher reduction potential in an electron-rich environment. Our finding provides new insights into the decomposition mechanisms of electrolytes and paves the way for the rational design of high-performance LMBs. (c) 2024 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.