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 Li 2 O with high mechanical strength and Li 3 N 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 –2 and maintained stable cycling for over 2000 h at a current density of 0.6 mA cm –2 . Consequently, the all-solid-state lithium cell assembled with the Li–Ag alloy anode with SEI, Li 6 PS 5 Cl solid electrolyte, and LiNi 0.78 Co 0.10 Mn 0.12 O 2 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 25 °C.