Ultrahigh‐Temperature‐Tolerance Lithium Metal Batteries Enabled by Molecular‐Level Polymer Configuration Design with Low‐Entropy‐Penalty Effect

Despite their immense potential for next-generation energy storage, the practical implementation of temperature-tolerant lithium metal batteries (LMBs) under extreme thermal conditions continues to face formidable challenges. In this study, an ultrahigh-temperature-tolerance polymer-based electrolyte (UPE) prototype with a low-entropy-penalty effect is proposed. This electrolyte features a carefully engineered molecular configuration that enables stable operation of polymer-based LMBs across a broad temperature range (25-150 °C). Comprehensive experimental and theoretical analyses confirm that the unique "ester-ether-fluorinated segment" architecture enables the formation of a robust coordination framework through Li⁺-multivalent ether/ester interactions and effective Li⁺-ether strong-solvent-cage decoupling. The resulting polymer electrolyte integrates reactive carboxyl groups, alkali-metal-soluble ether moieties, and fluorinated segments that provide inert yet efficient ion conduction pathways. This synergistic configuration achieves high ionic conductivity, significantly improved lithium-ion transference numbers, and excellent interfacial compatibility with lithium metal. This work presents a molecular-level polymer design framework, providing a compelling direction for the development of high-performance, thermally stable lithium-metal batteries.