Measurement and correlation for the electrical conductivity of double salt ionic liquids with triple ions

The neat ionic liquids 1-butyl-2,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C(4)C(1)C(1)im] [NTf2]), 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([C(4)C(1)C(1)im][BF4]), N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate ([Deme][BF4]), N,N-diethyl-N-methyl-N-(2-methoxye thyl) ammonium bis[(trifluoromethyl)sulfonyl]imide ([Deme][NTf2]) were used as parent ionic liquids to generate double salt ionic liquids (DSILs) with triple ions. The conductivity of DSILs [Deme]x[C(4)C(1)C(1)im](1-x)[NTf2], [Deme]x[C(4)C(1)C(1)im]((1-x))[BF4], [C(4)C(1)C(1)im][NTf2](x)[BF4]((1-x)) and [Deme] [NTf2](x)[BF4]((1-x)) were measured. There is a linear positive deviation for [Deme](x)[C(4)C(1)C(1)im]((1-x))[NTf2], [Deme](x)[C(4)C(1)C(1)im]((1-x))[BF4] and [C(4)C(1)C(1)im][NTf2](x)[BF4]((1-x)) , which indicates that most of the electrical conductivities of DSILs are greater than those of linear averages of the corresponding parent neat ionic liquids. The electrical conductivities of [Deme](x)[C(4)C(1)C(1)im]((1-x))[NTf2] and [Deme](x)[C(4)C(1)C(1)im]((1-x))[BF4] lie in the range of those of their corresponding parent neat ionic liquids. The electrical conductivity of [C(4)C(1)C(1)im][NTf2](x)[BF4]((1-x)) rises with the concentration of [NTf2], and it has a maximum value at x = 0.9, which is larger than either of its parent neat ionic liquids. There is a linear negative deviation for [Deme][NTf2](x)[BF4]((1-x)) , which indicates that most of the electrical conductivities of the DSIL is less than that of linear average of the corresponding parent neat ionic liquids. The electrical conductivity of the DSIL lies between those of its parent neat ionic liquids and increases with the concentration of [NTf2]. The VTF equation and the Arrhenius equation were utilized to correlate the temperature dependence of DSILs, and VTF equation is more accurate than Arrhenius equation. The relationships between parameters of VTF equation and ion composition can be expressed by first-order Fourier equation. A transformed VTF equation based on VTF and Fourier equation was proposed to describe the combined effects of ion composition and temperature on the electrical conductivity. The experimental electrical conductivities of DSILs were correlated by the transformed VTF equation, and the correlation results agree well with experimental data.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, double salt ionic liquids (DSILs) with triple ions were generated using parent ionic liquids. The conductivity of DSILs was measured and compared to that of the corresponding parent neat ionic liquids. The results showed that most DSILs had higher conductivity than the linear averages of the parent neat ionic liquids. The temperature dependence of DSILs was accurately described using the VTF equation and the relationships between parameters of the VTF equation and ion composition could be expressed by the first-order Fourier equation.