Synergistic Effects of Plasticizer and 3D Framework toward High-Performance Solid Polymer Electrolyte for Room-Temperature Solid-State Lithium Batteries

Solid polymer electrolytes (SPEs) can alleviate the safety issues existing in commercialized lithium ion batteries with liquid electrolyte. However, the low room-temperature ionic conductivity and poor mechanical properties of current polymer electrolyte hinder its practical applications. Herein, a composite solid polymer electrolyte consisting of poly(ethylene oxide) (PEO), the solid plasticizer succinonitrile (SN), and a 3D framework glass fiber (GF) with high ionic conductivity and good mechanical property is proposed. The optimized composite electrolyte PEO–SN25–LiTFSI10–GF has a room-temperature ionic conductivity of 2.85 × 10–4 S cm–1, which is 100 times higher than that of pristine PEO. An electrochemical window up to 5.5 V and a tensile strength of over 8 MPa are also exhibited by the optimized composite electrolyte. The solid-state LiFePO4/PEO–SN25–LiTFSI10–GF/Li battery shows good cyclic performance with a capacity retention of 98.5% after 100 cycles at 0.2 C under room temperature, demonstrating a promising polymer composite electrolyte for the next-generation solid-state lithium batteries with high energy density and high safety.