Synergistic Effects of Fluorinated Li‐Based Metal‐Organic Framework Filler on Matrix Polarity and Anion Immobilization in Quasi‐Solid State Electrolyte for Lithium‐Metal Batteries

Abstract Poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) based electrolyte is a promising alternative to liquid electrolytes in lithium metal batteries. However, its commercial application is limited by high crystallinity and low Li + ion conductivity. In this study, we synthesized a fluorinated Li‐based metal‐organic framework (Li‐MOF−F) and used it as a filler to address these limitations. The strategy for the Li‐MOF−F filler stands out in two main aspects: framework structure for rapid Li + ion transport and F‐functional group with electronegativity. The LiO 4 with π‐π conjugated dicarboxylate enables the reversible Li intercalation in the lattice structure. The fluorine atoms with electronegativity transform the polymer matrix from non‐polar to polar phase and immobilize TFSI − anions by electrostatic interaction. As a result, the PVDF‐HFP electrolyte with Li‐MOF−F (LMF‐PE) achieves the highest polarity and Li transference number. In Li/Li symmetric cell tests, LMF‐PE demonstrates stable Li plating/stripping behavior without dendrites. Additionally, we applied lithium nickel manganese cobalt oxide (NCM) with 94 % Ni content as a cathode material in cell test. LMF‐PE cell delivers a high initial discharge capacity of 226.9 mAh g −1 and 80 % capacity retention after 150 cycles, highlighting its superior cycling performance. These enhancements are attributed to the structural and electrostatic benefits of Li‐MOF−F.