Deeply Rechargeable and Hydrogen-Evolution-Suppressing Zinc Anode in Alkaline Aqueous Electrolyte

Metallic zinc as a rechargeable anode material for aqueous batteries has gained tremendous attention. Zn-air batteries, which operate in alkaline electrolytes, are promising with the highest theoretical volumetric energy density. However, rechargeable zinc anodes develop slowly in alkaline electrolytes due to passivation, dissolution, and hydrogen evolution issues. In this study, we report the design of a submicron zinc anode sealed with an ion-sieving coating that suppresses hydrogen evolution reaction. The design is demonstrated with ZnO nanorods coated by TiO₂, which overcomes passivation, dissolution, and hydrogen evolution issues simultaneously. It achieves superior reversible deep cycling performance with a high discharge capacity of 616 mAh/g and Coulombic efficiency of 93.5% when cycled with 100% depth of discharge at lean electrolyte. It can also deeply cycle ∼350 times in a beaker cell. The design principle of this work may potentially be applied to other battery electrode materials.