High‐Temperature and High‐Voltage Gel Polymer Electrolytes for Lithium‐Metal Batteries: Integrating Hybrid Molecular Engineering and In Situ Polymerization Strategy

Gel polymer electrolytes (GPEs) have emerged as promising candidates for lithium metal batteries (LMBs), yet their practical implementation remains constrained by limitations in high‐temperature and high‐voltage stability. Herein, a high‐temperature and high‐voltage electrolyte (PTCEA‐GPE) is designed by in situ click polymerization of multifunctional molecular monomers in liquid electrolytes. The PTCEA‐GPE has an extended electrochemical stability window of ≈5.6 V, a high lithium‐ion transference number (0.64), and excellent electrochemical stability. The Li|PTCEA‐GPE|LiFePO 4 batteries maintain capacity retention of 89.2% and 82.4% after 200 cycles at 120 and 150 °C, respectively. Even enabling the 4.5 V Li|PTCEA‐GPE|LiCoO 2 batteries to maintain almost constant capacity within 100 charge/discharge cycles. Moreover, 1‐Ah‐grade Li|PTCEA‐GPE|LiFePO 4 pouch batteries maintain capacity retention of 86.3% after 400 cycles, and they do not flame or explode in nail penetration tests. This work provides a good insight into the rational design of high‐temperature and high‐voltage GPEs for LMBs.