Rationally Designed Li-Ag Alloy with In-Situ-Formed Solid Electrolyte Interphase for All-Solid-State Lithium Batteries.

All-solid-state lithium batteries (ASSLBs) with sulfide-based solid electrolytes have attracted significant attention as promising energy storage devices, owing to their high energy density and enhanced safety. However, the combination of a lithium metal anode and a sulfide solid electrolyte results in performance degradation, owing to lithium dendrite growth and the side reactions of lithium metal with the solid electrolyte. To address these issues, a Ag-based Li alloy with a favorable solid electrolyte interphase (SEI) was prepared using electrodeposition and applied to the ASSLB as an anode. The electrochemically formed SEI layer on the Li-Ag alloy primarily comprised LiF and LiO with high mechanical strength and LiN with high ionic conductivity, which suppressed the formation of lithium dendrites and short-circuiting of the cell. The symmetric cell with the Li-Ag alloy achieved a critical current density of 1.6 mA cm and maintained stable cycling for over 2000 h at a current density of 0.6 mA cm. Consequently, the all-solid-state lithium cell assembled with the Li-Ag alloy anode with SEI, LiPSCl solid electrolyte, and LiNiCoMnO cathode delivered a high discharge capacity of 185 mAh g and exhibited good cycling performance in terms of cycling stability and rate capability at 25 °C.