All-solid-state lithium battery with high capacity enabled by a new way of composite cathode design

A simple way to assemble an all-solid-state lithium-ion battery with ultrahigh surface capacity and energy density was established. Polyethylene oxide-based solid-state electrolyte was prepared via solution method and nano-SiO 2 was added into the electrolyte to increase the conductivity. Thick compact LiFePO 4 pellet infused with dry polymer electrolyte was used as the composite cathode in the all-solid-state lithium battery . The compact composite cathode not only showed large ionic and electronic conductivity , but also provided sufficient “free space” to compensate the volumetric change of the active materials during cycling. The all-solid-state lithium battery (composite cathode/dry polymer electrolyte/Li) was cycled at a constant current density of 200   μA/cm 2 at 60   °C. A maximum discharge specific capacity of 157   mAh/g was achieved and the surface capacity reached 15   mAh/cm 2 , which was of critical significance for all-solid-state lithium batteries. Good capacity retention was achieved after 10   cycles and great rate performance was obtained. Even at a current density of 1000   μA/cm 2 , the battery delivered a specific discharge capacity of 71   mAh/g, corresponding to a surface capacity of 6   mAh/cm 2 . The experimental data demonstrated that the composite cathode was a promising design in high-performance bulk-type all-solid-state lithium batteries.