In situ grown superhydrophobic ZIF-71 layer enabling ultra-stable zinc anodes for long-cycle AZBs

Abstract

Aqueous zinc-ion batteries (AZIBs) are considered promising candidates for advanced energy storage systems due to their operational reliability and economic viability. However, practical application is hindered by challenges such as Zn dendrite growth, hydrogen evolution (HER) and corrosion reactions. In this study, an in situ growth strategy is introduced to fabricate a superhydrophobic ZIF-71 coating (ZIF-71(IS)@Zn) directly on the Zn anode surface. This method enhances interfacial adhesion and coating uniformity in comparison to conventional spray-coated techniques (ZIF-71(Sp)@Zn). The ZIF-71(IS) coating possesses intrinsic hydrophobicity due to –Cl groups and a dense structure, effectively preventing water molecule penetration and mitigating HER and corrosion. Density functional theory (DFT) calculations indicate that ZIF-71 promotes Zn²⁺ desolvation by reducing hydration energy and improves Zn²⁺ adsorption on the (002) crystal plane. Electrochemical evaluations reveal that ZIF-71(IS)@Zn exhibits an extended cycling lifespan of 3000 h at 1 mA cm⁻²/0.5 mA h cm⁻², surpassing the performance of ZIF-71(Sp)@Zn (1232 h) and bare Zn (531 h). Full cells paired with AlVO-NMP cathodes achieve an initial capacity of 335.1 mA h g⁻¹ at 5 A g⁻¹, maintaining 81.1% of capacity after 3000 cycles. Pouch cells retain 86.8% capacity after 2000 cycles at 2 A g⁻¹, demonstrating the feasibility of this strategy for stabilizing Zn anodes.