In Situ Coordinated MOF‐Polymer Composite Electrolyte for Solid‐State Lithium Metal Batteries with Exceptional High‐Rate Performance

The integration of metal organic frameworks (MOFs) and electrospun polymer fibers offers the potential to achieve uniform dispersion and high loading of fillers, providing a unique perspective for advancing composite solid electrolytes in solid-state lithium metal batteries. In this work, a composite solid electrolyte is fabricated through a combination of electrospinning and chemical immersion, facilitating the in situ nucleation and growth of HKUST-1 on polyacrylonitrile (PAN) electrospun nanofibers. The in situ coordinated HKUST-1 particles not only modify the solvation structure of Li⁺ and the coordination environment of TFSI^-, but also encapsulate PAN fibers to mitigate interfacial side reactions with lithium metal, thereby improving interfacial stability. Consequently, the solid-state electrolyte achieves a high Li ion transference number of 0.77 and an impressive critical current density of 4.5 mA cm^-2. The assembled Li||Li symmetric cell exhibits stable operation for over 4000 h at 4.0 mA cm^-2, while Li||LFP and Li||NCM811 cells demonstrate exceptional rate capability and cycling stability. This work provides valuable insights into the design and fabrication of MOF/polymer-based composite solid electrolytes.