Air exposure towards stable Li/Li₁₀GeP₂S₁₂ interface for all-solid-state lithium batteries

Moist air is a great challenge for manufacturing sulfide-based all-solid-state lithium batteries as the water in air will lead to severe decomposition of sulfide electrolytes and release H₂S gas. However, different with direct reaction with water, short-period air exposure of Li₁₀GeP₂S₁₂ sulfide electrolyte with controlled humidity can greatly enhance the stability of Li₁₀GeP₂S₁₂ against lithium metal, thus realizing stable Li₁₀GeP₂S₁₂ based all-solid-state lithium metal batteries. During air exposure, partial hydrolysis reaction occurs on the surface of Li₁₀GeP₂S₁₂ pellets, rapidly generating a protective decomposition layer of Li₄P₂S₆, GeS₂ and Li₂HPO₃ in dozens of seconds. This ionically conductive but electronically insulation protecting layer can effectively prevent the severe interface reaction between Li₁₀GeP₂S₁₂ and lithium metal during electrochemical cycling. The Li/40s-air-exposed Li₁₀GeP₂S₁₂/Li cell shows long cycling stability for 1000 h. And the LiCoO₂/40s-air-exposed Li₁₀GeP₂S₁₂/Li batteries present good rate capability and long cyclic performances, showing capacity retention of 80% after 100 cycles.