Binary glycerol-based deep eutectic solvents containing zinc nitrate hexahydrate salt for rechargeable zinc air batteries applications with enhanced properties

Abstract

Deep eutectic solvents (DESs) have attracted interest due to their unique and favorable electrochemical characteristics. This study reported a novel binary glycerol-zinc salt deep eutectic solvents were prepared with a combination of hydrogen bond donor (glycerol (Gly)) and hydrogen bond acceptor (Zinc nitrate hexahydrate (ZNH)) at different molar ratios of 1:2, 1:3, 1:4, 1:5, and 1:6. The various physicochemical properties including viscosity, refractivity index, conductivity, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance (EIS) were measured. The results showed that among the various combinations tested, DES 1:2 resulted in a low viscosity value of 690, 500, 310, 220, and 160 mPa (mPa s) at shear rate ( S −1 ) values of 20, 30, 60, 100, and 200 respectively. Moreover, DES 1:2 resulted in more electrochemically stable solvents with a lower refractive index value of 1.446, and a higher conductivity ( σ ) of 4.41 mS/cm. The findings found disclose the features, nature and of properties of prepared DESs as a potential solvents for different electrochemical storage applications.