A Heteroanionic Zinc Ion Conductor for Dendrite-Free Zn Metal Anodes

Although zinc-based batteries are promising candidates for eco-friendly and cost-effective energy storage devices, their performance is severely retarded by dendrite formation. As the simplest zinc compounds, zinc chalcogenides, and halides are individually applied as a Zn protection layer due to high zinc ion conductivity. However, the mixed-anion compounds are not studied, which constrains the Zn²⁺ diffusion in single-anion lattices to their own limits. A heteroanionic zinc ion conductor (Zn_y O_{1- x} F_x ) coating layer is designed by in situ growth method with tunable F content and thickness. Strengthened by F aliovalent doping, the Zn²⁺ conductivity is enhanced within the wurtzite motif for rapid lattice Zn migration. Zn_y O_{1- x} F_x also affords zincophilic sites for oriented superficial Zn plating to suppress dendrite growth. Therefore, Zn_y O_{1- x} F_x -coated anode exhibits a low overpotential of 20.4 mV for 1000 h cycle life at a plating capacity of 1.0 mA h cm^-2 during symmetrical cell test. The MnO₂ //Zn full battery further proves high stability of 169.7 mA h g^-1 for 1000 cycles. This work may enlighten the mixed-anion tuning for high-performance Zn-based energy storage devices.