Improving zinc anodes with a vapor-deposited uniform ultrathin copper layer for enhanced ion distribution and dendrite suppression

Abstract

Aqueous zinc ion batteries are a promising technology for rechargeable batteries due to their low cost and high safety. However, the interfacial behavior between the zinc anode and the electrolyte often leads to critical issues such as the hydrogen evolution reaction, corrosion, and the formation of zinc dendrites. While protective layers on the zinc anode can improve performance, they may also increase impedance, reduce conductivity, and compromise electric field uniformity. To address these challenges, we developed a novel approach by applying an ultrathin copper (Cu) coating on a zinc anode (Cu@Zn) via a vacuum vapor deposition technique. This method achieves precise nanoscale control over the coating thickness, resulting in a uniform and defect-free protective layer that significantly enhances zinc ion nucleation and effectively suppresses dendrite formation. The symmetric Cu@Zn//Cu@Zn cells cycled over 1200 hours at 5 mA cm⁻² and 1 mA h cm⁻², surpassing 1000 hours at a high current density of 10 mA cm⁻². The full-cell testing conducted at a current density of 1 A g⁻¹ showed a significantly improved cycling stability, with the capacity decay rate reduced from 0.085% to 0.056% per cycle over 1000 charge–discharge cycles. This study presents a viable approach that offers significant potential for advancing battery technology.