Design Strategies, Characterization Mechanisms, and Applications of MOFs in Polymer Composite Electrolytes for Solid‐State Lithium Metal Batteries

Solid composite electrolytes (SCEs) composed of functional fillers and solid polymer electrolytes (SPEs) can overcome some shortcomings of single‐phase and combine some advantages of each component, and are considered as high‐performance solid‐state electrolytes (SSEs) candidates for assembling solid‐state lithium metal batteries (SSLMBs) with high safety and high energy density. In recent years, due to high designability of metal–organic frameworks (MOFs), MOFs/polymer composite electrolytes (MPCEs) have become a highly promising novel type of SCEs. Based on the above content, this article first describes the composition and mechanism of action of MPCEs, followed by a discussion on typical fabrication methods for MPCEs. In addition, the mechanisms of unmodified neat MOFs in improving performance for SSEs and enhancing interface stability are presented in detail, with a focus on the design strategies of MOFs and their applications in MPCEs, including dimensional design, ligand design, IL@MOFs design, and hybrid design. Finally, a thorough analysis is conducted on the current challenges faced by MPCEs, and corresponding future development directions are proposed. This review presents a comprehensive, systematic, and easily understandable analysis of the application and mechanism of action of different MOFs designs in MPCEs, providing a new perspective for researchers to study high‐performance SSEs.