Ultra-thin, Scalable, and MOF Network-Reinforced Composite Solid Electrolyte for All-Solid-State Lithium Metal Batteries

Ultra-thin, scalable solid-state electrolytes with high mechanical strength are essential for achieving high-performance all-solid-state lithium metal batteries (ASSLMBs). Among various types of solid-state electrolytes, composite solid electrolytes (CSEs) have emerged as an appealing option due to their ability to overcome the limitations of single-component solid-state electrolytes. In this study, ZIF-67 metal-organic framework (MOF) nanoparticles were self-assembled in situ on polyimide (PI) film fibers (referred to as PI@ZIF-67) to create continuous Li + transport channels. The ultra-thin, robust PI fiber film combined with MOF particles imparts high mechanical strength and excellent flexibility to the CSE. Additionally, the abundant sub-nanopores and surface Lewis acidic sites in ZIF-67 nanoparticles facilitate the dissociation of lithium salts and enhance the rapid transport of Li + . Consequently, 95% of the discharge capacity retention of the all-solid-state Li/PI 60 @ZIF-67-PEO/LFP cell was maintained after 300 cycles at 0.2C and 60 °C. Furthermore, an ultra-long lifespan of 3500 h at 0.2 mA cm -2 and 0.2 mAh cm -2 was achieved for the symmetric Li/PI 60 @ZIF-67-PEO/Li cell. The superior electrochemical performances are attributed to the effective Li + transport network and the high mechanical properties established by the continuous ZIF-67 particles within the PI 60 @ZIF-67-PEO CSE. This work presents a promising method for the integrated design of ultrathin CSEs that exhibit high ionic conductivity and exceptional mechanical robustness, making them suitable for ASSLMBs.