Advanced Design and Characterization of Polyether‐Based Solid‐State Electrolytes for High‐Energy‐Density Lithium Batteries

Abstract Polyether‐based solid‐state electrolytes have shown great potential in lithium batteries due to their excellent interfacial flexibility and high solvation ability for lithium salts. However, the problems of limited ion transport and insufficient interfacial stability have restricted the application of polyether‐based electrolytes in high‐energy‐density lithium batteries. To tackle these problems, researchers have explored a variety of strategies, such as multi‐component compounding and structural regulation, and developed a vast array of solid‐state electrolytes. Therefore, this review first summarizes the key modification strategies and representative examples of electrolytes from a systematic design perspective, aiming at the two aforementioned major issues. Meanwhile, to precisely implement the above strategies and to design more effective modification strategies, latent yet valuable structure–property relationships should be further uncovered. Thus, multiscale characterizations are rationally integrated through representative case studies. Finally, it summarizes the reported performance of representative polyether‐based solid‐state pouch cells, emphasizes scale‐up and batch‐to‐batch consistency, and outlines future research directions for translating these electrolytes into high‐energy, market‐ready batteries.