Density, dynamic viscosity, electrical conductivity, electrochemical potential window, and excess properties of ionic liquid N-butyl-pyridinium dicyanamide and binary system with propylene carbonate

Abstract

The densities, dynamic viscosities, and electrical conductivities of the ionic liquid (IL) N-butyl-pyridinium dicyanamide ([C4py][DCA]) and its binary system with propylene carbonate (PC) were measured at the temperature range from 288.15 to 353.15K over the whole composition range at atmospheric pressure. In addition, some significant thermodynamic parameters were also estimated. The excess molar volumes (VE) and dynamic viscosity deviations (Δη) of the mixtures were calculated, and the change of VE and Δη were fitted by the Redlich–Kister (R–K) polynomial equation. The temperature dependences of dynamic viscosities and electrical conductivities of the binary system under the whole concentration range (molar ratio of IL from 1 to 0) were graphically described by the Vogel–Fulcher–Tamman (VFT) equation and Arrhenius equation. Through the Walden rule, the ionicity of binary system at each concentration was evaluated as a function of the temperature from 288.15 to 353.15K. Further, according to three-electrode method, the electrochemical potential windows (EPWs) of binary system (xIL=1.0000, 0.7885, 0.4997, 0.1003) were measured to investigate the electrochemistry stability. In a supercapacitor, the IL mixtures of two molar ratios (xIL=1.0000, 0.7885) were applied as electrolytes, and the performance of the supercapacitors were determined by cyclic voltammetry (CV) method.