Enhanced Air Stability and Li Metal Compatibility of Li‐Argyrodite Electrolytes Triggered by In2O3 Co‐Doping for All‐Solid‐State Li Metal Batteries

Sulfide solid electrolytes (SSEs) have become an ideal candidate material for all‐solid‐state Li metal batteries (ASSLMBs) because of their high ionic conductivity. However, the vile Li incompatibility and poor air stability of SSEs barriers their commercial application. Herein, novel Li6+2xP1−xInxS5−1.5xO1.5xCl (0 ≤ x ≤ 0.1) SSEs are synthesized via In and O co‐doped Li6PS5Cl. By regulating the substitution concentration, the prepared Li6.12P0.92In0.08S4.88O0.12Cl exhibits considerable ionic conductivity (2.67 × 10−3 S cm−1) and enhanced air stability. Based on the first‐principles density functional theory (DFT) calculation, it is predicted that In3+ replaces P5+ to form InS45− tetrahedron and O2− replaces S2− to form PS3O4− group. The mechanism of enhancing air stability by In, O co‐substituting Li6PS5Cl is clarified. More remarkably, the formation of Li‐In alloys induced by Li6.16P0.92In0.08S4.88O0.12Cl electrolyte at the anode interface is beneficial to reducing the migration barrier of Li‐ions, promoting their remote migration, and enhancing the stability of the Li/SSEs interface. The optimized electrolyte shows superior critical current density (1.4 mA cm−2) and satisfactory Li dendrite inhibition (stable cycle at 0.1 mA cm−2 over 3000 h). The ASSLMBs with Li6.16P0.92In0.08S4.88O0.12Cl electrolyte reveal considerable cycle stability. This work emphasizes In, O co‐doping to address redox issues of sulfide electrolytes. Herein, a novel Li6+2xP1−xInxS5−1.5xO1.5xCl (0 ≤ x ≤ 0.1) SSEs based on Argyrodite‐type is synthesized by In and O co‐doped Li6PS5Cl. The effect of In, O co‐substitution on ionic conductivity and air stability is investigated via experimental methods and DFT calculations. The enhanced interfacial Li compatibility of the modified electrolyte is also revealed.