Sphere‐Confined Reversible Zn Deposition for Stable Alkaline Aqueous Batteries

Abstract The practical applications of alkaline zinc‐based batteries are challenged by poor rechargeability with an insufficient zinc utilization ratio. Herein, a sphere‐confined reversible zinc deposition behavior from a free‐standing Zn anode is reported, which is composed of bi‐continuous ZnO‐protected interconnected and hollowed Zn microspheres by the Kirkendall effect. The cross‐linked Zn network with in situ formed outer ZnO shell and inner hollow space not only inhibits side reactions but also ensures long‐range conductivity and accommodates shape change, which induces preferential reversible zinc dissolution‐deposition process in the inner space and maintains structural integrity even under high zinc utilization ratio. As a result, the Zn electrode can be stably cycled for 390 h at a high current density of 20 mA cm⁻² (60% depth of discharge), outperforming previously reported alkaline Zn anodes. A stable zinc‐nickel oxide hydroxide battery with a high cumulative capacity of 8532 mAh cm⁻² at 60% depth of discharge is also demonstrated.