Electrochemical, Transport, and Spectroscopic Properties of 1-Ethyl-3-methylimidazolium Ionic Liquid Electrolytes Containing Zinc Dicyanamide

Abstract

The electrochemical, physical, and transport properties of 1-ethyl-3-methylimidazolium dicyanamide [emim][dca] containing varying levels of Zn2+ and H2O have been investigated to evaluate the suitability of dicyanamide (dca–) ionic liquids (ILs) for applications in secondary zinc–air batteries. Electrochemical experiments indicate that [emim][dca] containing Zn(dca)2 can support high current density Zn0/Zn2+ deposition and stripping, at Zn(dca)2 concentrations up to 40 mol % and H2O concentrations of 10 wt %. Physical property experiments show that good conductivities can be obtained in these IL/Zn2+ systems. The [emim][dca] containing 30 mol % Zn(dca)2 electrolyte displayed higher conductivities (15 mS·cm–1 at 25 °C) than the same IL containing 30 mol % ZnCl2 (12 mS·cm–1 at 25 °C). A significant difference in the solvation environments of the Zn2+ in the two IL/zinc salt mixtures has been suggested to be the cause of the significant improvement in physical and electrochemical properties of [emim][dca] containing Zn(dca)2 over the more extensively studied ZnCl2.