Uniform Liquid–Confined Copolymer Gel Enables Wide‐Temperature Lithium Metal Batteries (−20 to 90 °C)

Abstract Gel polymer electrolytes (GPEs) promise to combine the high ionic conductivity of liquids with the mechanical robustness of solids for lithium metal batteries. However, temperature‐induced phase separation compromises interfacial stability at elevated temperatures while hindering Li‐ion transport at low temperatures. Here a liquid‐confinement topology is reported that immobilizes a continuous liquid phase within an ultralow‐content (3 wt.%) copolymer scaffold to overcome these limitations. By employing kinetically regulated in situ copolymerization of trifluoroethyl methacrylate and N,N‐dimethyl acrylamide, a sparse yet cross‐linked network is constructed, topologically confining the electrolyte to create uninterrupted Li‐ion conduction pathways. This approach enables the gel electrolyte to resist phase separation or solvent loss up to 90 °C, while maintaining fast ionic conductivity even at −20 °C. The performance of this GPE is validated in Li||LiNi 0.6 Co 0.2 Mn 0.2 O 2 cells (≥ 2.5 mAh cm −2 ), which retain 81.9% capacity over 300 cycles at 90 °C and achieve 97.5% retention at −20 °C. Furthermore, Ah‐scale pouch cells exhibit suppressed gas evolution and resistance to thermal runaway, even under 90 °C cycling conditions. This topology‐guided design bridges the gap between liquid‐like ionic transport and solid‐state safety, providing a scalable solution for high‐energy lithium metal batteries operable across a wide temperature range.