The use of Li metal anode is important for developing all-solid-state Li rechargeable batteries with high energy densities. In this study, all-solid-state Li symmetric cells using sulfide electrolytes in the Li3PS4-LiI system were fabricated to investigate the Li dissolution/deposition cycling performance. A cell using 54Li3PS4·46LiI (mol%) glass electrolyte was cycled at a current density of 1.25 mA cm−2 for 3400 h at 100 °C without short-circuiting, and the highest areal capacity of 7.5 mAh cm−2 was achieved. Structural analyses of the interface between Li and solid electrolytes revealed that the reduction of electrolyte by the Li metal was suppressed by adding LiI to Li3PS4, and good interfacial contact was maintained even after prolonged cycling. The addition of LiI to Li3PS4 glass improved the tolerance to reduction with Li metal, and enhanced the Li dissolution/deposition cycling performance.