Linker fluorinated metal-organic frameworks enhancing ion conduction for fast-charging lithium metal batteries

Composite solid-state electrolytes incorporating metal–organic frameworks (MOFs) demonstrate tremendous potential for ameliorating Li+ conduction in lithium metal batteries. However, their practical application is hindered by low ionic conductivity and unstable Li+ transport at the electrode interfaces. To overcome these challenges, a previously unreported family of indium‑based MOFs (In-BDC-Fx, x = 0, 4, 6) with tunable fluorine content was synthesized and integrated into PVDF-HFP matrices to construct high-performance quasi-solid-state electrolytes. By systematically modulating linker fluorination, a bifunctional enhancement mechanism is revealed: fluorinated indium centers simultaneously suppress polymer crystallinity and establish preferential Li+ conduction pathways. Remarkably, In-BDC-F6 manifests exceptional synergistic interactions between –CF3 functionalities and indium coordination sites, amplifying Lewis acidity to facilitate LiTFSI dissociation and TFSI− immobilization, culminating in homogeneous LiF-enriched solid electrolyte interphases. The optimized electrolyte demonstrates compelling electrochemical performance: ionic conductivity of 9.68 × 10−4 S cm−1, Li+ transference number of 0.70, and electrochemical stability window of 4.96 V. Li||Li symmetric cell demonstrated a critical current density of 3.5 mA cm−2 and stable plating/stripping for over 1000 h at 0.2 mA cm−2, while LiFePO4||Li cells retain 96.66 % capacity after 1300 cycles at 10C, underscoring the transformative potential of fluorinated MOF architectures in fast-charging solid-state batteries.