Defect‐Rich Functional HfO2‐x for Highly Reversible Zn Metal Anode

Abstract Interface engineering attracted tremendous attention owing to its remarkable ability to impede dendrite growth and side reactions in aqueous zinc‐ion batteries. Artificial interface layers composed of crystalline materials have been extensively employed to stabilize the Zn anode. However, the diffusion kinetics of Zn 2+ in highly crystalline materials are hindered by steric effects from the lattice, thereby limiting the high‐rate performance of the cell. Here, defect‐rich HfO 2‐x polycrystals derived from metal‐organic frameworks (MOFs) (D‐HfO 2‐x ) are developed to enhance the Zn deposition behavior. The discrepancy of dielectric constants between metallic Zn and HfO 2 enables the building of an electrostatic shielding layer for uniform Zn deposition. More importantly, the oxygen vacancies in D‐HfO 2‐x provide abundant active sites for Zn 2+ adsorption, accelerating the kinetics of Zn 2+ migration, which contributes to the preferential exposure of the Zn (002) plane during plating. Consequently, the D‐HfO 2‐x ‐modified Zn anode delivers ultrastable durability of over 5000 h at 1 mA cm −2 and a low voltage hysteresis of 30 mV. The constructed defective coating provides a guarantee for the stable operation of Zn anodes, and the innovative approach of defective engineering also offers new ideas for the protection of other energy storage devices.