Sustainable Release of LiNO3 from a Fluorine-Decorated Metal–Organic Framework Separator to Enable High-Performance Li-Metal Batteries in Carbonate Electrolytes

High-voltage Li-metal batteries hold great prospects for boosting energy density, while the Li-metal anodes show poor compatibility with high-voltage tolerant carbonate electrolytes, leading to unstable solid-electrolyte interphase (SEI) and uncontrolled Li dendrites growth. Herein, a F-decorated UIO-66/polyimide (PI) functional separator encapsulated with LiNO₃ (LNO@UIO-66F/PI) is rationally designed to regulate the interfacial chemistry and Li deposition behavior. Specifically, the UIO-66F nanoparticles in situ grown on the PI fibers form continuous electronegative nanochannels, which promote rapid and uniform Li⁺ flux while repelling the anion migration. Furthermore, the LiNO₃ encapsulated in the UIO-66F nanopores sustainably releases to form a thin and conductive Li₃N-rich SEI. This synergy effect induces a dense and spherical Li deposition behavior, effectively inhibiting the growth of Li dendrites. Consequently, this LNO@UIO-66F/PI separator demonstrates highly reversible Li plating/stripping over 1000 h at an extremely high current density of 10 mA cm⁻² in carbonate electrolytes, and also enables the stable cycling of Li||LiNi_0.8Co_0.1Mn_0.1O₂ cell over 1000 cycles under a high cut-off voltage of 4.5 V, paving the way for practical application of high-energy-density Li-metal batteries.