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

Abstract

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.