Formation of electrode–electrolyte interface by lithium insertion to SnS–P2S5 negative electrode materials in all-solid-state cells

All-solid-state cells with the SnX–P2X5 (X = S and O) glassy electrodes and the ce:inf>S/ce:inf>S–P2S5 glass-ceramic electrolytes were fabricated, and their electrochemical performance was examined. The 67SnS·33P2S5 (mol%) glassy electrode exhibited higher capacity of about 400 mAh g− 1 than the 67SnO·33P2O5 glass and the SnS crystal. In the case of using the 67SnS·33P2S5 glass as an active material, the cell using the composite electrode consisting of active material and conductive additive (acetylene-black) powders showed almost the same charge–discharge behaviors as the cell using the conventional composite electrode consisting of active material, conductive additive, and the solid electrolyte powders. The similarity of cell performance suggests that the highly Li+ ion conductive ce:inf>S/ce:inf>S–P2S5 solid electrolytes were formed by electrochemical Li insertion to the SnS–P2S5 electrode; the self-formed electrolyte supplied a Li+ ion conduction path in the composite electrode. A close electrode–electrolyte interface, which is important to develop all-solid-state batteries, would be established by utilizing the self-formation process of solid electrolyte.