Robust MOF-Based Composite Solid-State Electrolyte Membrane for High-Performance Lithium–Metal Batteries

In this work, we construct a robust MOF-based flexible composite membrane based on PVDF-HFP, UIO-66, and ionic liquid (IL). Through their synergistic reinforcement effect, the obtained solid-state electrolytes can simultaneously achieve high ionic conductivity, good mechanical properties, and flame retardance. The abundant pores of the MOF are capable of loading IL, which not only builds continuous ion channels and facilitates the dissociation of Li⁺ but also balances the mechanical properties and electrochemical performance. Consequently, the as-prepared electrolyte membranes exhibit excellent ionic conductivity (5.55 × 10^-4 S cm^-1), high Li⁺ transference number (0.52), moderate electrochemical window (4.3 V), outstanding mechanical properties (tensile strength of 6.63 MPa and elongation of 232%), and good interfacial stability (stable Li plating/stripping behavior). Meanwhile, the assembled LiFePO₄//Li battery exhibits an excellent rate capability and long cycle stability. This work demonstrates a realistic strategy for the fabrication of MOF-based composite SSEs toward next generation high-performance lithium metal batteries.