Rationally Designed Li-Ag Alloy with in-Situ Formed Solid Electrolyteinterphase for All-Solid-State Lithium Batteries

Sulfide-based all-solid-state lithium metal batteries (ASSLBs) have attracted enormous attention as promising energy storage device due to their high energy density and enhanced safety. However, the combination of lithium metal anode and sulfide electrolytes leads to performance degradation due to the lithium dendrite growth and side reactions of lithium metal with solid electrolyte. In order to address these issues, many studies have been conducted to control the interface by modification of lithium metal (e.g. surface coating, Li-based metal alloy, Li with buffer layer etc.). In this work, the Ag-based Li alloy with favorable solid electrolyte interphase (SEI) was prepared by electrodeposition and applied to the ASSLB as an anode. The electrochemically formed SEI layer on Li-Ag alloy was mainly consisted of LiF and Li2O with high mechanical strength, and Li3N with high ionic conductivity, which suppressed the lithium dendrite and short-circuit of the cell. The symmetric cell employing Li-Ag alloy achieved a critical current density of 1.6 mA cm-2 and maintained stable cycling over 2000 h at current density of 0.6 mA cm-2. Consequently, the all-solid-state lithium cell assembled with Li-Ag alloy anode with SEI, Li6PS5Cl solid electrolyte and LiNi0.78Co0.10Mn0.12O2 cathode delivered a high discharge capacity of 185 mAh g-1 and exhibited good cycling performance in terms of cycling stability and rate capability at 30 oC