Chemical stability of Li4PS4I solid electrolyte against hydrolysis

Sulfide solid electrolytes in the Li3PS4-LiI system are promising for all-solid-state batteries owing to their high ionic conductivity in the order of 10(-4) S cm(-1) and electrochemical stability. Nonetheless, the low chemical stability tendency of sulfide-based materials under ambient atmosphere is a critical issue due to the generation of toxic H2S gas. In this study, the chemical stability of Li4PS4I (Li3PS4-LiI) solid electrolyte under ambient atmosphere was investigated and compared with that of Li3PS4 to analyze the effect of the incorporation of LiI on the chemical stability of sulfide-based electrolytes. No generation of H2S gas was detected in the Li4PS4I solid electrolyte after an exposure of 60 min to the ambient atmosphere with high relative humidity of 40%. The hydrolysis suppression is attributed to the formation of LiI center dot H2O, acting as a protective barrier between PS43- units in the electrolyte and H2O molecules in air. The structural reversibility of Li4PS4I by simple drying at 180 degrees C was confirmed and the solid electrolyte exhibited an ionic conductivity of 10(-4) S cm(-1) at room temperature, similar to that of the sample before the exposure to the ambient atmosphere. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The chemical stability of Li4PS4I solid electrolyte was investigated under ambient atmosphere and compared with Li3PS4, showing effective suppression of H2S gas generation and good structural reversibility attributed to LiI incorporation. The solid electrolyte exhibited consistent ionic conductivity at room temperature before and after exposure to ambient atmosphere.