Enhancing the Stability of Metallic Li Anodes for Aprotic Li-O2 Batteries with Dual-Anion Electrolytes.

Abstract

Despite the impressive specific capacity of Li-O2 batteries, challenges persist, particularly with lithium metal anode (LMA). These include dendritic growth and unstable solid electrolyte interface (SEI) layers, which become more pronounced in an oxygen-rich environment, a typical operation scenario for Li-O2 batteries. Herein, utilizing a hybrid dual anion electrolyte (DAE) strategy, which incorporates both inorganic LiNO3 and organic Li[(FSO2)(C2F5SO2)N] (LiFPFSI) salts, the dendritic growth is evidently inhibited by creating a "concrete-like" SEI structure. Simultaneously, it fosters the development of a fluorine-rich SEI layer. Consequently, a robust, compact, and stable barrier is formed, adeptly suppressing side reactions between LMA and the electrolyte, particularly those relevant to dissolved O2. The practicality and efficiency of this DAE strategy are validated across a variety of battery types including Li/Li, Li/Cu, and notably Li-O2 batteries, which showcased significantly improved reversibility and durability. These results underscore the important role of multifunctional salts in interphase engineering for LMA, which could lead to advancements in Li-O2 batteries.