Structural change of Li2S–P2S5 sulfide solid electrolytes in the atmosphere

The sulfides Li2S−P2S5 are attractive solid electrolytes for all-solid-state lithium batteries since they have high lithium-ion conductivities and wide electrochemical windows. However, chemical stability of Li2S-P2S5 solid electrolytes in the atmosphere is concerned. In the present study, the structure of Li2S−P2S5 glasses and glass-ceramics after exposure to air was investigated for the first time. Raman spectroscopy demonstrated that the 75Li2S∙25P2S5 (mol%) glass and glass-ceramic composed of Li+ and PS43− ions did not exhibit obvious structural changes on exposure to the atmosphere. The amount of H2S generated from Li2S−P2S5 glasses exposed to air depended on the glass composition. The composition of 75Li2S∙25P2S5 generated the least amount of H2S of Li2S−P2S5 binary systems. 75Li2S∙25P2S5 glass and glass-ceramic are promising solid electrolytes for all-solid-state lithium batteries in terms of chemical stability and conductivity.