Determination of transport parameters in [EMIm]Cl-based Ionic Liquids - Diffusion and electrical conductivity

The density, electrical conductivity and diffusion coefficients of anions and cations in the ionic liquid AlCl3/1-ethyl-3-methylimidazolium chloride, [EMIm]Cl, were determined to study physical correlations of these important parameters. The density was measured for different molar ratios of AlCl3:[EMIm]Cl from 0.5:1 to 2.0:1 at ambient temperature. The diffusion coefficient of the electrochemically active heptachloroaluminate complex, Al2Cl7-, was measured for a molar ratio of 2:1 in the range of 25 degrees C to 100 degrees C. The corresponding current density and potential transients were discussed regarding the decomposition of the [EMIm]+ cation and deviation from the theoretical Cottrell behavior. The electrical conductivity was measured for molar ratios of 1.5:1 and 2:1 in the range of 25 degrees C to 100 degrees C. Both the diffusion coefficient and electrical conductivity can be described well by an Arrhenius law. The diffusion coefficients of AlCl4-, Al2Cl7- and [EMIm](+) were estimated from the Nernst-Einstein and Stokes-Einstein relation. The results indicate a strong impact of ion pairing in these electrolytes. (c) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study measured the density, electrical conductivity, and diffusion coefficients of anions and cations in the ionic liquid AlCl3/1-ethyl-3-methylimidazolium chloride, [EMIm]Cl, and investigated the physical correlations of these parameters. The results indicate a strong impact of ion pairing in these electrolytes.