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 x 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.