Development of 4V-Class Bulk-Type All-Solid-State Lithium Rechargeable Batteries by a Combined Use of Complex Hydride and Sulfide Electrolytes for Room Temperature Operation

We have operated a 4V-class bulk-type, all-solid-state LiCoO2/Li battery at room temperature. The battery consisted of a Li4(BH4)3I complex hydride electrolyte as the electrolyte layer, and a 80Li2S 20P2S5 sulfide glass as an electrolyte in the positive electrode layer. The assembled battery exhibited a 92 mAh g−1 initial discharge capacity at 298 K and 0.1 C. The discharge capacity for the 20th cycle remained as high as 83 mAh g−1, corresponding to a capacity retention ratio of nearly 90%.