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

Abstract

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 À 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.

Intermolecular Interactions and Electrochemical Studies on Highly Concentrated Acetate-Based Water-in-Salt and Ionic Liquid Electrolytes

“…The appearance of the peak only for these electrodes is due to their electrocatalytic properties toward oxygen reduction. , The intensity of this peak decreases with the increase in concentration of the salt and ionic liquid, which could be due to the lower solubility of oxygen in these electrolytes compared to 1 m LiOAc, where the intensity of the peak was about 55 μA cm –2 . A decrease in the solubility of oxygen with an increase in the concentration of electrolyte was also observed in other acetate-based mixed-cation water-in-salt electrolytes. , …”

“…A decrease in the solubility of oxygen with an increase in the concentration of electrolyte was also observed in other acetate-based mixed-cation water-in-salt electrolytes. 42,49 Two additional cathodic waves are observed at more negative potentials for Pt, Au, and stainless steel electrodes in the mixed LiOAc + EMImOAc solutions for concentrations higher than 7 m each (Figure 5 and S7). For instance, Figure 5 shows that in the 16.6 m LiOAc + 10 m EMImOAc electrolyte, the peaks are located at −0.8 and −1.4 V for Pt, at −1.2 and −1.7 V for Au, and at −1.35 and −1.75 V for stainless steel.…”

Does Water‐in‐Salt Electrolyte Subdue Issues of Zn Batteries?

“…Zinc Plating and Discussion about Side-Products in WISE Amiri et al studied the Zn nucleation mechanism in acetatebased WISE on glassy carbon electrodes. [62] The analysis of the temporally varying current density and potentiostatic curves revealed the diffusion-controlled 3D nucleation and growth of Zn.…”

“…Amiri et al studied the Zn nucleation mechanism in acetate‐based WISE on glassy carbon electrodes. [ 62 ] The analysis of the temporally varying current density and potentiostatic curves revealed the diffusion‐controlled 3D nucleation and growth of Zn. In principle, the deposition occurs through progressive nucleation at potentials greater than −1.29 V vs Ag/AgCl, which becomes instantaneous with the application of further negative potentials.…”

Effect of anion on water-in-salt/solid interfacial structures investigated by atomic force microscopy

“…[2][3][4][5][6] The high electrochemical stability of WiS is also advantageous for electrochemical deposition of various metals, such as chromium, rhenium, and so on because it suppresses hydrogen generation during the metal deposition. [7][8][9] Since both of these processes mainly occur on the liquid/solid interfaces, high-resolution structural analysis on the WiS/solid interfaces is crucially important.…”