High‐Entropy Oxide Coating for Stabilizing Zn Metal Anodes in Aqueous Zn‐Ion Batteries

ABSTRACT Rechargeable aqueous zinc‐ion batteries have garnered considerable attention due to their intrinsic safety, high theoretical capacity, and low cost. However, problems such as zinc dendrite growth, hydrogen evolution reaction, and severe corrosion hinder their practical deployment. Herein, we fabricate a homogeneous high‐entropy oxide powder (Co _0.2 Cu _0.2 Mg _0.2 Ni _0.2 Zn _0.2 )O with a single‐phase rock‐salt structure, as a protective artificial interphase for the Zn anode. The multicomponent oxide layer enables selective Zn ²⁺ adsorption and enhanced ion migration uniformity. Furthermore, its intrinsic hydrophobicity and strong desolvation ability suppress parasitic side reactions, thereby facilitating uniform and reversible Zn plating/stripping. As a result, the modified Zn anode exhibits an ultralong cycling lifespan of 1800 h at 10 mA cm ⁻² in a 2 M ZnSO ₄ electrolyte, and retains 750 h of stable cycling even in a natural seawater‐based ZnSO ₄ system at 20 mA cm ⁻² . This approach is further validated with a compositional variation—(Co _0.2 Cu _0.2 Mn _0.2 Ni _0.2 Zn _0.2 )O—demonstrating robust cycling over 1300 h at 10 mA cm ⁻² . Furthermore, full cells assembled with an I ₂ cathode show enhanced electrochemical performance. These findings highlight the dual roles of high‐entropy materials in simultaneously accelerating the kinetics of Zn ²⁺ transport and homogenizing zinc deposition, offering a promising strategy for the stabilization of zinc metal anodes in aqueous batteries.