Entropy‐Mediated Nonporous Polymer Separator Unlocks Ultra‐Wide Temperature Range (−70°C to 150°C) Lithium Metal Batteries

ABSTRACT

The separator, as an indispensable component in batteries, has attracted extensive attention. Nevertheless, its poor temperature adaptability restricts the application of lithium (Li) metal batteries under extreme temperature scenarios. Herein, we develop a novel nonporous high‐entropy separator (HES) based on a rationally designed high‐entropy polymer, achieving for the first time, from the perspective of the separator, the long‐term operation of Li metal batteries from −70 to 150°C. The as‐prepared HES delivers superior electrolyte wettability and thermal stability. Moreover, the abundant ion transport channels in HES homogenize and accelerate ion transport, while facilitating the formation of stable, inorganic/B‐rich solid electrolyte interphase and cathode electrolyte interphase in the Li metal batteries. These effectively inhibit Li dendrites and parasitic reactions across a wide temperature range. Consequently, Li||Li cells operate for 2200 h at −70°C, 6548 h at 25°C, and 700 h at 150°C. Li||V ₂ O ₅ batteries can run from −70 to 150°C, demonstrating excellent application potential. This work enriches separator design strategies and expands the temperature boundaries for the application of Li metal batteries.