Fluorine-Decorated Metal-Organic Framework Separators Enable Ion-Screening Effects for Dendrite-Free Zinc Deposition

Aqueous zinc-ion batteries (AZIBs) have emerged as a promising complement to lithium-ion batteries due to their inherent safety benefits. However, the cycle life of AZIBs is severely limited by the poor stability of zinc anodes, manifested in uncontrolled dendritic growth and persistent side reactions, which hinder wider application. Herein, we report an ion-selective separator (UIO-66-4F/GF) achieved by in situ growth of a fluorine-functionalized metal–organic framework (UIO-66-4F) onto commercial glass fiber (GF). The synergistic mechanism, involving electrostatic repulsion between -F groups and anions along with strong interactions between -F and Zn²⁺ cations, effectively restricts migration, suppresses 2D Zn²⁺ diffusion across electrode interfaces, and enhances [Zn(H₂O)₆]²⁺ desolvation. Furthermore, the -F groups enable precise regulation of interfacial electric fields and Zn²⁺ concentration gradients, thereby homogenizing ion flux to realize dendrite-free Zn deposition. The UIO-66-4F separator achieves stable ZnZn cell operation for 1500 h at 1 mA cm⁻² via oriented deposition and sustains long-term cycling over 1000 h at 1 mA cm⁻², and delivers a ZnCu cell with 99.4% Coulombic efficiency. Moreover, the ZnUIO-66-4F/GFNH₄V₄O₁₀ full cell represents an ultrastable cycling stability with a high capacity retention of 90% after 500 cycles at a current density of 1 A g⁻¹.