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

-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.