Three different DES electrolytes were used: hydrated 0.3 M ZnSO4 in reline (abbreviated ChU0.3), anhydrous 0.3 M ZnSO4 in reline (abbreviated AChU), 0.1 M ZnSO4 (abbreviated ChU0.1), and 0.3 M ZnSO4 in ethaline (abbreviated ChEG). Reline was first prepared by combining urea (CO(NH2)2, ACS (New York, NY, USA) reagent, 99%) and choline chloride (C5H14ClNO, Sigma-Aldrich (St. Louis, MO, USA) 99%) (2:1 molar ratio) at a temperature of 70 °C for 1 h until a homogeneous colorless solution was obtained. Then, ZnSO4 was added to reline to obtain ChU0.3 and ChU0.1 DES electrolytes. A pre-drying process was performed to eliminate the crystallization water of choline chloride, urea and ZnSO4 powders by heating these powders separately at 120 °C under a rotary-pump vacuum for 2 days. After drying, the chemicals were transferred to an argon-filled glove box for the preparation of anhydrous reline, which was then used for the preparation of AChU. Ethaline was prepared with the same procedure as reline using ethylene glycol (C2H6O2) (reagent plus, ≥99% Sigma-Aldrich) instead of urea. ChU0.3 and ChEG were then selected as electrolytes for the mechanistic studies of Zn electrodeposition reported in Section 2.1 and Section 2.2.
Emanuele E., Li Bassi A., Macrelli A., Mele C., Strada J, & Bozzini B. (2023). Zinc Electrode Cycling in Deep Eutectic Solvent Electrolytes: An Electrochemical Study. Molecules, 28(3), 957.
