Investigating the physicochemical and transport properties of LiTFA ionic liquids by molecular dynamics simulation

The physicochemical properties of a new lithium ionic liquid (LiTFA) such as density, viscosity, ionic conductivity, and self-diffusion coefficient were calculated using molecular dynamics simulations. The backbone of this new lithium ionic liquid is oligo-ethylene glycol monomethyl ether (n = 3). The structure of this new ionic liquid was initially optimized by the density functional theory (DFT). The optimized structure showed that the net charge of LiTFA in the gas phase was less than vertical bar +/- 1e vertical bar. This optimized structure was used in MD simulations to calculate physicochemical and transport properties of this new lithium ionic liquid. Calculated results for density, viscosity, ionic conductivity, and self-diffusion coefficient at 303 K were consistent with the experimental data. Moreover, the mechanism of ionic migration in the lithium ionic liquid matrix was investigated in details. Results showed that the mechanism of lithium cation migration can be described by lithium ions hopping from one cage to another and ion pair transfer from one point to another. Also, according calculated results, it was concluded that the main reason for low ionic conductivity of this new ionic liquid is low rate of cation migration from one cage to another or low rate of ion pair transfer in the system. (C) 2014 Elsevier B.V. All rights reserved.