Rational design of an Ag@MOF functional separator for controlled lithium deposition and enhanced interfacial stability in lithium metal batteries

The increasing demand for high-energy–density batteries has driven intensive research into lithium metal batteries (LMBs) as promising alternatives to conventional lithium-ion batteries. Despite their ultrahigh theoretical capacity, lithium metal anodes (LMAs) suffer from uncontrolled dendrite growth, leading to safety hazards and irreversible capacity loss. Herein, we develop a functional separator based on a composite of Ag nanoparticles (NPs) and metal–organic frameworks (MOFs) to enhance LMA stability. The –NH₂ groups in MOFs promote Li⁺ desolvation and transport, while Ag NPs induce the in-situ formation of a Li-Ag alloy interphase, effectively suppressing dendrite growth and improving interfacial lithiophilicity. As a result, the reversibility and Li plating/stripping kinetics of LMAs are significantly enhanced. The Li symmetric cells exhibit an ultralong lifespan of 2000 h at 0.2 mA cm⁻² and 1000 h at 0.5 mA cm⁻². Moreover, the Li||LiFePO₄ full cell retains 93.3 % of its initial capacity after 2000 cycles at 1C and maintains 45 mAh g⁻¹ even at an ultra-high rate of 15C.