Sphere-Confined Reversible Zn Deposition for Stable Alkaline Aqueous Batteries

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.