High lithium ion conduction of sulfide glass-based solid electrolytes and their application to all-solid-state batteries

Sulfide glass-based solid electrolytes prepared by melt quenching and mechanical milling were reviewed. The sulfide and oxysulfide glass–ceramic electrolytes in the system Li2S–P2S5–P2O5 with superionic Li7P3S11 and Li3.25P0.95S4 crystals exhibited high conductivity of over 10−3 S cm−1 at room temperature and high electrochemical stability. Newly designed all-sulfide batteries 80SnS·20P2S5/80Li2S·20P2S5/75Li2S·25Cu were successfully fabricated; reversible charge–discharge capacities of more than 400 mAh g−1 were observed after the second to 10th cycles. The operation of those all-sulfide lithium secondary batteries is a first step for the realization of the all-solid-state monolithic batteries.