A new carbon-incorporated lithium phosphate solid electrolyte

A novel carbon-incorporated lithium phosphate (LiCPON) solid electrolyte is prepared to overcome the deterioration of lithium phosphorus oxynitride (LiPON) via hydrolysis reaction in air as well as improve its ionic conductivity for application in all-solid-state batteries. Physical and electrochemical properties of LiCPON electrolyte have been systematically investigated. The ionic conductivities of LiCPON is about 3.06 × 10−6 S cm−1, while relatively low ionic conductivity of 7.46 × 10−7 S cm−1 is achieved for LiPON. All-solid-state thin-film LiFeFe(CN)6/LiCPON/Li full cell consists of two unit cells externally connected in parallel delivers a high discharge capacity of 7.8 mAh. The high overall voltage of 5.0 V is achieved for two unit cells connected in series. XPS results reveal that the addition of C in LiPON can alleviate the hydrolysis reaction of LiPON and improve its chemical stability in air. Overall, high ionic conductivity and improved air stability make glassy LiCPON a promising new electrolyte for all-solid-state Li metal batteries.