Integrating Lithium Sulfide as a Single Ionic Conductor Interphase for Stable All‐Solid‐State Lithium–Sulfur Batteries

Abstract As a very prospective solid‐state electrolyte, Li 10 GeP 2 S 12 (LGPS) exhibits high ionic conductivity comparable to liquid electrolytes. However, severe self‐decomposition and Li dendrite propagation of LGPS will be triggered due to the thermodynamic incompatibility with Li metal anode. Herein, by adopting a facile chemical vapor deposition method, an artificial solid electrolyte interphase composed of Li 2 S is proposed as a single ionic conductor to promote the interface stability of LGPS toward Li. The good electronic insulation coupled with ionic conduction property of Li 2 S effectively blocks electron transfer from Li to LGPS while enabling smooth passage of Li ions. Meanwhile, the generated Li 2 S layer remains good interface compatibility with LGPS, which is verified by the stable Li‐plating/stripping operation for over 500 h at 0.15 mA cm −2 . Consequently, the all‐solid‐state Li–S batteries (ASSLSBs) with a Li 2 S layer demonstrate superb capacity retention of 90.8% at 0.2 mA cm −2 after 100 cycles. Even at the harsh condition of 90 °C, the cell can deliver a high reversible capacity of 1318.8 mAh g −1 with decent capacity retention of 88.6% after 100 cycles. This approach offers a new insight for interface modification between LGPS and Li and the realization of ASSLSBs with stable cycle life.