Zinc Electrodeposition in Acetate-based Water-in-Salt Electrolyte: Experimental and Theoretical Studies

Zinc electroplating has found applications in many fields. The chemical composition of the electrodeposition bath can have a great impact on the final coating quality and the economics of the process. In traditional aqueous electrolytes, zinc deposition competes with the hydrogen evolution and oxygen reduction reactions, which can lead to hydrogen embrittlement of the substrate as well as decrease in efficiency. Highly concentrated water-in-salt electrolytes can suppress these reactions significantly. Here, we show that electrodeposition of zinc with high efficiencies can be achieved using an acetate-based water-in-salt electrolyte at room temperature. Nucleation studies confirm that at potentials more negative than -1.30 V vs. Ag/AgCl, the three-dimensional (3D) nucleation process becomes instantaneous, while at more positive potentials it is progressive. Using two of the most common nucleation and growth models, Scharifker-Mostany and Mirkin-Nilov-Heerman-Tarallo, nucleation parameters such as the nucleation rate constant and nuclei density are found, showing a good agreement between the two models.