Entropy‐Driven Modulation of Ion Clustering and Polymer Crystallinity for Low‐Temperature Lithium Metal Batteries

Abstract Solid‐state Li metal batteries have garnered significant attention for their intrinsic safety and high energy density. Among various solid‐state electrolytes, solid polymer electrolytes (SPEs) offer their excellent processability and interfacial compatibility but suffer from the formation of large ionic clusters and crystallization, which hinder Li + transport and desolvation, particularly at low temperatures (e.g., deep‐sea conditions). In this study, a multicomponent strategy is adopted to enhance the configurational entropy of SPEs, resulting in a 2‐fold reduction in Li cluster size and suppression of polymer crystallization. These changes facilitate rapid desolvation and promote the formation of a high‐entropy solid electrolyte interphase. Owing to these benefits, the resulting SPEs exhibit an 8.5‐fold improvement in ionic conductivity at −20 °C (0.17 mS cm −1 ). The Li/Cu cells exhibit an impressive average Coulombic efficiency (CE) of 98.59% over 300 cycles at room temperature, and maintain nearly unchanged CE even after a temperature drop to −20 °C. Furthermore, the Li/LiFePO 4 cells (N/P = 4) achieve a 13‐fold capacity improvement and an average capacity retention of 91.49% after 500 cycles at −20°C (over 248 days). This strategy builds a new approach for high performance SPEs for practical low‐temperature operation.