In Situ Spectroscopic Probing of Oxygen Crossover Effects on Solid Electrolyte Interphase in Aprotic Lithium-Oxygen Batteries

摘要

The solid electrolyte interphase (SEI) on lithium metal anodes (LMA) plays acritical role in affording a long lifespan required for aprotic lithium-oxygen(Li-O_2) batteries. Nevertheless, the crossover of oxygen from the cathode tothe anode, an inevitable phenomenon for most of the current Li-O_2 batteries,and its effects on the formation and operation of SEI on LMA remain lessexplored. In this work, a mechanistic study of the SEI formation at a modelCu/dimethyl sulfoxide (DMSO) interface in the presence of oxygenis presented. Direct spectroscopic evidence coupled with theoreticalcalculation reveals that oxygen can alter the SEI formation pathway and resultin distinct SEI properties. Specifically, oxygen can inhibit the fission of the C-Sbond of DMSO solvent and therefore reduce the formation of unstable SEIcomponents (e.g., C≡C species) and volatile products (e.g., C_2H_6 and H_2).Thus, the SEI formed under oxygen is more uniform and of less voids, andenables improved electrochemical performance of LMA. This work presentsnew insights into the oxygen crossover effects on SEI chemistry and isbeneficial for designing better LMA/electrolyte interface for future Li-O_2batteries.