Study of Solid Polymer Electrolytes for Room Temperature All-Solid-State Lithium Ion Batteries

All-solid-state lithium ion batteries based on solid polymer electrolytes (SPEs) have shown high commercialization and technical values. However, severe capacity decay of the batteries occurs as a decrease of working temperature. This is mainly due to low lithium ionic conductivity of SPEs at room temperature. Hence, preparation of SPEs with high ionic conductivities for wide temperature applications of all-solid-state lithium ion batteries remains a challenge. In this study, preparation, structure and electrochemical properties of SPEs as well as fabrication of all-solid-state lithium ion batteries using the SPEs are investigated. Results show that lithium ionic conductivity and electrochemical stability of the SPEs can be adjusted by simultaneously grafting cyclic carbonate and combed poly(ethyleneoxide) on polysiloxane. The LiFePO₄/Li batteries with the SPEs present excellent cycling performance in the temperature range from 25 to 100 ^oC.