Improvement of chemical stability of Li3PS4 glass electrolytes by adding MxOy (M = Fe, Zn, and Bi) nanoparticles

Sulfide glasses in the system Li2S–P2S5 are attractive as solid electrolytes for all-solid-state lithium batteries because of their high conductivity and high electrochemical stability. In the present study, we have focused on chemical stability in air of the sulfide glass electrolytes and succeeded in suppressing H2S generation by preparing composite electrolytes of the Li3PS4 glass and one of the metal oxides with the formula MxOy (MxOy: Fe2O3, ZnO and Bi2O3). The H2S amounts generated decreased in the order of the composite with Fe2O3, ZnO, and Bi2O3. It is noteworthy that the use of a favorable MxOy with a larger negative Gibbs energy change (ΔG) for the reaction with H2S is effective in improving the chemical stability of sulfide electrolytes. The composite electrolyte of 90Li3PS4·10ZnO (mol%) exhibited a relatively high ionic conductivity of over 10−4 S cm−1, negligible electronic conductivity and a wide electrochemical window over 5 V. The all-solid-state In/LiCoO2 cell using the 90Li3PS4·10ZnO composite electrolyte operated as a lithium secondary battery with excellent cycleability at room temperature.