Interface Layer Engineering of Zinc Anode for Durable Seawater-Based Zinc-Ion Batteries

The direct utilization of seawater as an electrolyte in zinc-ion batteries demonstrates significant potential for energy storage applications. However, the harsh conditions of seawater pose challenges, such as corrosion, dendrite formation, and hydrogen evolution reactions, which severely impede practical implementation. Herein, a series of seawater-corrosion-resistant coating layers (zinc acetylacetonate (ZA)/zinc hydroxide (Zn(OH)₂)/zinc oxide (ZnO)/zinc fluoride (ZnF₂)/lithium fluoride (LiF)) are respectively constructed on the surface of the zinc anode by ultrasonic spraying technology. Based on the systematic electrochemical tests and theoretical calculations, the ZA layer exhibits superior chloride-ion blocking performance, enhanced zinc affinity and nucleophilicity owing to its unique organometallic complex structure, promoting the desolvation polarization behavior and reversible deposition behavior of Zn²⁺ ions. Consequently, the ZA@Zn symmetric cell exhibits an outstanding long-cycle performance of 4268 h at 5 mA cm^-2. The Zn//ZA@Cu asymmetric cell exhibits a high Coulombic efficiency (CE) of 99.47% after 650 cycles at 4 mA cm^-2, and the ZA@Zn//NH₄V₄O₁₀ battery retains a high capacity of 213.7 mAh g^-1 after 2000 cycles at 6 A g^-1 with minimal capacity fade. This work will guide future design and fabrication of interface modifications for dendrite-free metal anodes in seawater batteries.