Computational analysis of conductivity contributions in an ionic liquid mixture of 1-ethyl-3-methylimidazolium dicyanamide and tetrafluoroborate.

Abstract Ionic liquid mixtures not only possess the well-known advantages of pure ionic liquids, but allow for a continuous and very exact fine-tuning of physico-chemical properties. Molecular dynamics simulations are a valuable tool for understanding the molecular processes that govern the behavior of IL mixtures. Considering electrochemical applications, especially the accurate prediction of dynamics is of great interest. In this work, we investigate mass and charge transport properties of binary mixtures of 1-ethyl-3-methylimidazolium tetrafluoroborate [C 2 mim][BF 4 ] and 1-ethyl-3-methylimidazolium dicyanamide [C 2 mim][N(CN) 2 ]. Due to the high statistical accuracy required for the reliable calculation of transport properties, we employ a coarse-grained model of the ionic liquids which is validated by comparison to experimental data. Via calculation of the non-Gaussian parameter, we find that the dynamics in this ionic liquid mixture are heterogeneous for all ion species. To elucidate how the constituents of the mixture influence overall dynamics, separate contributions of the ion species to the total conductivity are analyzed.