Developing a lithiophilic, solvent-phobic dual-functionality film for dendrite-free Li metal anodes

Li metal anodes (LMAs) are promising candidate for advanced batteries that encounters significant challenges, including electrolyte corrosion and uneven deposition. These issues not only reduce battery lifespan but also pose safety risks due to the uncontrolled growth of dendrites. Herein, we introduce a lithiophilic, solvent-phobic dual-functionality film (LSDF) designed to tackle these problems. The LSDF features an inner layer of polyethylene oxide directly applied to the LMAs and an outer layer of poly(vinylidene fluoride-co-hexafluoropropylene) facing the electrolyte. Both layers contain N-ethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, which enhances the rapid transport of Li ions. The inner layer promotes high interfacial stability, while the outer layer offers solvent resistance and Li affinity, thereby inhibiting dendrite growth and reducing side reactions. Consequently, Li||Li symmetric cells achieve stable cycling for 1650 h with a minimal overpotential of 15 mV at 3 mAh cm⁻² and 3 mA cm⁻². Additionally, full cells paired with LiFePO₄ cathodes maintain 85 % capacity retention over 500 cycles at 1 C and demonstrate excellent rate capability. This study presents a new approach to modulate the interface of LMAs, significantly enhancing its stability for high-energy–density battery applications.