Bulk-type All-solid-state Lithium Secondary Batteries Using Highly Ion-conductive Sulfide Solid Electrolyte Thin Films

Abstract

LiCoO₂ particles were coated with 33Li₄GeS₄·67Li₃PS₄ (mol%) solid electrolyte (SE) thin films by pulsed laser deposition (PLD). The all-solid-state cells using positive electrodes, composed of only LiCoO₂ particles coated with SE thin films, were fabricated and their electrochemical performances were investigated. The cell was charged and discharged with a higher capacity of 67 mAh g⁻¹ than that using LiCoO₂ particles without SE-coating. Moreover, the capacity of all-solid-state cell increased to 80 mAh g⁻¹ after enhancing the ionic conductivity of SE thin films by heat treatment at 200°C. The use of highly lithium-ion conductive thin films was effective in the formation of sufficient lithium-ion conduction paths in positive electrodes for bulk-type all-solid-state batteries.