Mechanically Stable UV-Crosslinked Polyester-Polycarbonate Solid Polymer Electrolyte for High-Temperature Batteries

Abstract

Due to the mechanism with which solid polymer electrolytes use to conduct ions, these materials are generally more suitable for high-temperature applications where the ionic conductivity is sufficient and where liquid electrolytes show insufficient stability. To enable high-temperature cycling of polymer electrolytes, the mechanical stability has to be improved. Herein, we report successful long-term cycling of a solid polyester-polycarbonate – poly(ϵ-caprolactone-co-trimethylene carbonate) (poly(CL-co-TMC)) – electrolyte cross-linked through the addition of multifunctional acrylates and the use of UV-irradiation, allowing stable cycling of cells for more than 100 cycles at 80 °C, with good rate capabilities (0.2 mA cm−2) and Coulombic efficiencies exceeding 99 %. Both the mechanical properties and the ionic conductivity of the mechanically stabilized poly(CL-co-TMC) were investigated and optimized to reduce the frequency dependence of the moduli while still achieving an acceptable ionic conductivity at elevated temperature. These results indicate that the poly(CL-co-TMC) system can straight-forwardly be modified to allow for higher-temperature applications.