Ionic liquids containing an alkyl sulfate group as potential electrolytes

Various types of ionic liquid (IL) containing an alkyl sulfate group are synthesized and their physical and electrochemical properties are investigated. The temperature dependency of dynamic viscosity and ionic conductivity are measured for these ILs. The low temperature phase behaviour of the ethylsulfate salts is investigated using differential scanning calorimetry. Three ethylsulfate-containing ionic liquids exhibit wide electrochemical windows of about 5.0 V, and one pyrrolidinium-containing ionic liquid shows a conductivity of 3.8 mS cm−1. The various cations of alkylsulfate-containing ionic liquids are shown to greatly influence viscosity, density, and conductivity. Absorbance solvatochromic probe, Nile Red is used to investigate the relative polarity of alkylsulfate base ionic liquids compared with several organic solvents. The electrochemical and thermal stabilities of these ILs make them promising electrolytes for use in electrochemical devices.