Terminally functionalized polymer electrolytes with enhanced interfacial compatibility for robust solid-state lithium metal batteries

Solid-state lithium metal batteries (SSLMBs) with high-voltage cathodes offer significant potential for next-generation energy storage but face challenges related to poor oxidative stability and interfacial incompatibility of polymer electrolytes (PEs). Herein, terminally functionalized polymer electrolytes (TFPEs) with chain polymer backbones were designed to enhance the antioxidation resistance and interfacial compatibility. Introduced the electron-withdrawing group of isocyanate (–NCO) at the end of the polymer chain to eliminate the end hydroxy (–OH), which can enhance the interfacial compatibility and antioxidative decomposition capacity for PEs. The terminally functionalized poly (1,6-hexanediol) carbonate diols polymer electrolytes (TFPCDL) deliver good electrochemical stability, wide electrochemical stability window (4.7 V), and high ionic conductivity (3.75 × 10⁻⁴ S cm⁻¹ at 25°C). Batteries employing TFPCDL demonstrated stable cycling performance with 88% capacity retention after 100 cycles when charged to 4.5 V. This work not only highlights a promising strategy for designing antioxidative PEs but also accelerates the practical application of SSLMBs with advanced cathode materials.