Fluorine-, Nitrogen-, and Boron-Functionalized Polymer Electrolytes for Advanced Lithium Metal Batteries

Polymer electrolytes (PEs) have emerged as alternatives to conventional liquid electrolytes in lithium metal batteries (LMBs) by addressing critical safety and performance challenges, including flame hazards, dendrite growth, and interfacial instability. While oxygen-based PEs, such as poly(ethylene oxide), have been widely investigated, their limited ionic conductivity and susceptibility to electrochemical degradation under high-voltage operation have prompted the exploration of heteroatom-functionalized PEs. Incorporating heteroatoms significantly enhances ion transport, electrochemical stability, and mechanical properties─all critical factors for robust and reliable LMB performance. This review focuses on fluorine-, nitrogen-, and boron-functionalized PEs, highlighting their distinctive features and design strategies for LMB applications. Recent developments and key design principles are summarized in the context of high-performance PEs for safer and more reliable LMBs for advanced energy storage applications.