In Situ Formed Ag‐Li Intermetallic Layer for Stable Cycling of All‐Solid‐State Lithium Batteries

Abstract With the timely advent of the electric vehicle era, where battery stability has emerged as a major issue, all‐solid‐state batteries (ASSBs) have attracted significant attention as the game changer owing to their high stability. However, despite the introduction of a densely packed solid electrolyte (SE) layer, when Li is used to increase the energy density of the cell, the short‐circuit problem caused by Li protrusion is unavoidable. Furthermore, most strategies to control nonuniform Li growth are so complicated that they hinder the practical application of ASSBs. To overcome these limitations, this study proposes an Ag‐Li alloy anode via mass‐producible roll pressing method. Unlike previous studies reporting solid‐solution‐based metal alloys containing a small amount of lithiophilic Ag, the in situ formed and Ag‐enriched Ag‐Li intermetallic layer mitigates uneven Li deposition and maintains a stable SE/Ag‐Li interface, facilitating reversible Li operation. Contrary to Li cells showing frequent initial short‐circuit, the cell incorporating the Ag‐Li anode exhibits a better capacity retention of 94.3% for 140 cycles, as well as stable cycling even under 12 C. Through a facile approach enabling the fabrication of a large‐area anode with controllable Li growth, this study provides practical insight for developing ASSBs with stable cyclabilities.