Development of 4 V-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 4 V-class bulk-type, all-solid-state LiCoO2/Li battery at room temperature. The composition consisted of a Li4(BH4)3I complex hydride electrolyte for the electrolyte layer, and a 80Li2S 20P2S5 sulfide glass for an electrolyte in the positive electrode layer. The battery assembled 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%.