Constructing Zn-Cu Alloy Layers via Trace Copper Salt Modulation: An Effective Strategy for Stabilizing Zinc Anodes in Aqueous Zinc-Ion Batteries

Zinc anode corrosion and dendrite growth in aqueous zinc-ion batteries remain critical challenges that significantly hinder practical application and long-term cyclability. Herein, we present an interface engineering strategy mediated by trace amounts of copper salts, enabling the in situ formation of a uniform and dense Cu-Zn alloy layer on the zinc foil surface for effective anode interface optimization. The CuZn5@Zn composite anode not only lowers the nucleation barrier for Zn2+ deposition and promotes uniform zinc plating to effectively suppress dendrite proliferation but also suppresses parasitic reactions at the electrode/electrolyte interface, thereby contributing to enhanced electrode structural integrity. Electrochemical measurements reveal that the CuZn5@Zn symmetric cell exhibits a stable cycling performance for over 400 h at 1 mA·cm−2 and 1 mAh·cm−2. The CuZn5@Zn||Cu half-cell maintains high reversibility over 500 cycles under 5 mA·cm−2 and 1 mAh·cm−2, achieving a Coulombic efficiency of 98.7%. Moreover, the CuZn5@Zn//VO2 full cell retains 80.2% of its initial capacity after 200 cycles, significantly outperforming the bare Zn anode, which retains only 39%. This study offers insights into the regulation of zinc anode interface performance via trace metal salt engineering.