Dual-Functional Ga/F Co-Doped Argyrodite Sulfide Electrolytes for All-Solid-State Lithium Batteries

Sulfide solid electrolytes (SEs) are considered a top contender for next-generation energy storage systems due to their high ionic conductivity and relatively “soft” mechanical properties. Nevertheless, interface hydrolysis in air and reduction at the Li/SE interface hinder their practical application in all-solid-state batteries. In this work, a novel chemically stabilized argyrodite-based SE Li 5.58 P 0.96 Ga 0.04 S 4.5 Cl 1.38 F 0.12 was developed by co-doping Ga, F in Li 5.5 PS 4.5 Cl 1.5 (LPSC), which has an excellent ionic conductivity of 4.5 mS/cm at 25 °C. Notably, the co-doping strategy promotes the formation of lithium-friendly Li–Ga alloys and electron-insulating LiF at the Li/SE interface, which plays an essential role in regulating the uniform plating/stripping of Li + and suppressing the interfacial side reactions. The Li symmetric cells exhibit a high critical current density of 1.8 mA/cm 2 and stable cycling for 2,000 h at 0.2 mA/cm 2 . Furthermore, the Ga, F co-doped electrolyte exhibits substantial structural stability at 30% relative humidity, further demonstrated by the density functional theory calculations. When paired with LiNi 0.8 Co 0.1 Mn 0.1 O 2 or LiCoO 2 cathodes, the all-solid-state lithium metal cells demonstrate outstanding cycle stability and rate performance. Owing to their superior air stability and compatibility with Li metal, Ga/F co-doped LPSCs are poised to become the next generation of all-solid-state lithium batteries.