Stabilizing Zinc Coordination Chemistry and Interfacial Water Reactivity with Acetohydroxamic Acid for Highly Reversible Zinc Anodes

Zinc acetate electrolytes have attracted increasing attention for aqueous zinc-ion batteries owing to their intrinsic buffering capability, tunable coordination chemistry, and cost advantages. However, the dynamically evolving Zn2+ coordination environment, coupled with water-induced interfacial side reactions, leads to uneven Zn plating/stripping. Herein, acetohydroxamic acid (AHA), introduced at a concentration comparable to that of zinc acetate, serves as a compatible cosolute to simultaneously regulate Zn2+ coordination and interfacial water chemistry. Solvation analyses demonstrate that AHA participates in and reconstructs the Zn2+ coordination network through partial replacement of acetate in the primary solvation shell, thereby stabilizing the dynamically evolving coordination environment. Meanwhile, preferential adsorption of AHA on the Zn surface and the reorganized water hydrogen-bond network reduce interfacial water accessibility to reactive Zn sites. The cooperative regulation of coordination and interfacial water chemistry effectively suppresses water-induced parasitic reactions and promotes homogeneous Zn plating/stripping. Consequently, the optimized electrolyte delivers highly reversible stability for over 2500 h in Zn||Zn symmetric cells and enables an average Coulombic efficiency of 98.3% maintaining over 500 cycles in Zn||Cu cells. This work presents a cosolute-mediated strategy that synergistically stabilizes bulk Zn2+ coordination and interfacial water chemistry, providing new insights into electrolyte design for highly reversible zinc acetate-based aqueous batteries.