<i>In situ</i> construction of porous ZnO layer with more exposed (002) polar facets toward long-cycling zinc metal anodes

The presence of high theoretical capacity, superior safety, and cost-effectiveness makes aqueous zinc-ion batteries (AZIBs) an attractive option for various applications. However, the extensive growth of dendrites on zinc anodes in aqueous electrolytes has impeded the further commercialization of AZIBs. The formation of dendrites serves as a primary driver for substantial side reactions, including hydrogen evolution, corrosion, and the emergence of a passivation layer, thereby compromising batteries during cycling. In this study, we fabricated a modified zinc anode (p-ZnO@Zn), which is protected by porous ZnO (p-ZnO) layer featuring more exposed (002) polar facets, through a simple one-step chemical vapor process. The presence of p-ZnO physically isolates the direct exposure of the zinc foil to the electrolyte, significantly mitigating the hydrogen evolution reactions. Moreover, p-ZnO with more exposed (002) polar facets promotes oriented deposition of Zn (002), while its high affinity for zinc balances the electric field across the zinc electrode surface. This uniform plating reduces the nucleation and growth of zinc dendrites. Additionally, the porous structure of p-ZnO provides more sites and channels for zinc-ion deposition. When applying a current density of 5 mA cm−2, the p-ZnO@Zn symmetric cell exhibited prolonged cycling performance lasting 2900 h. With MnO2 as the positive electrode, the assembled MnO2//p-ZnO@Zn full batteries and soft-pack batteries provide excellent rate capability and cycle stability. Consequently, the p-ZnO@Zn significantly enhances the cycle life of AZIBs and offers potential for their commercialization.