Sandwich-Like Poly(propylene carbonate)-Based Electrolyte for Ambient-Temperature Solid-State Lithium Ion Batteries

A poly(propylene carbonate) (PPC)-based sandwich-like composite solid polymer electrolyte (SE) was designed and applied to solid-state lithium ion batteries at 25 °C. The sandwich-like structure of the composite SE was composed of three parts. A polypropylene separator was used as a support membrane to enhance the strength of the SE membrane. Succinonitrile in the PPC-based SE was used to increase the ionic conductivity. Pure PPC as a buffer layer was closed to the lithium anode, which could improve the interface compatibility, Coulombic efficiency, and cycle life of batteries. The sandwich-like composite SE exhibited good comprehensive properties such as a high ion transference number (0.65), sufficient ionic conductivity (2.18 × 10–4 S cm–1 and 5.77 × 10–4 S cm–1 at 25 and 55 °C, respectively), and outstanding electrochemical stability at ambient temperature. Furthermore, a Li/LiFePO4 cell with the sandwich-like composite SE delivered a discharge capacity close to 140 mA h g–1 (0.1 C) at 25 °C. The results suggested that a sandwich-like PPC-based electrolyte is a promising SE for solid-state batteries.