Dendrite-Free Zinc Anode for Zinc-Based Batteries by Pre-Deposition of a Cu–Zn Alloy Layer on Copper Surface via an In Situ Electrochemical Oxidation–Reduction Reaction

The prevention of uncontrollable growth of zinc dendrites on the zinc electrodes is one of the key challenges, hindering the widespread commercialization of zinc-based energy storage technologies. Herein, we report a facile method to mitigate dendrite growth on a copper surface by an initial in situ coating of a Cu–Zn alloy layer, before zinc deposition. During further zinc deposition, the initially formed Cu–Zn alloy layer provides uniform nucleating sites and promotes homogeneous zinc deposition. A symmetrical cell, assembled using a Cu–Zn/Cu electrode could be stably cycled for over 1000 cycles in ZnSO₄ solution, at a current density of 30 mA/cm² and a coulombic efficiency of 99.9%. A zinc–air cell, assembled using Zn@Cu–Zn/Cu as the anode and rGO/Co₃O₄ composite as the cathode, exhibited a very stable performance at a high current density of 50 mA/cm² and coulombic efficiency of ~93%, for over 400 cycles. After cycling experiments, the X-ray photoelectron spectroscopy and the X-ray diffraction analysis confirmed the formation of the Cu–Zn alloy layer. Hence, the present method provides an easy route for fabricating a dendrite-free zinc electrode, for a wide range of zinc anode-based batteries.