All-solid-state lithium secondary batteries with oxide-coated LiCoO 2 electrode and Li 2S–P 2S 5 electrolyte

Abstract

All-solid-state lithium secondary batteries using LiCoO 2 active materials coated with Li 2SiO 3 and SiO 2 oxide films and Li 2S–P 2S 5 solid electrolytes were fabricated and their electrochemical performance was investigated. The electrochemical performace of the all-solid-state cells at a high voltage region was highly improved by using oxide-coated LiCoO 2. The oxide coatings are effective in suppressing the formation of an interfacial resistance between LiCoO 2 and the solid electrolyte at a high cutoff voltage of 4.6 V (vs. Li). As a result, charge–discharge capacities and cycle performance at the cutoff voltage were improved. The cell with Li 2SiO 3-coated LiCoO 2 showed a large initial discharge capacity of 130 mAh g −1 and a good capacity retention of 110 mAh g −1 after 50th cycles at the cutoff voltage of 4.6 V (vs. Li).