Impact of lithium salt addition on ionic transporting properties in a binary ionic liquid electrolyte composed of 4-(2-methoxyethyl)-4-methylmorpholinium bis(trifluoromethanesulfonyl)imide and LiTFSI

We conducted a study on the transport properties of an ionic liquid 4-(2-methoxyethyl)-4-methylmorpholin-4-ium bis(trifluoromethylsulfonyl)amide ([MorMEOM][TFSI]) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI)-doped [MorMEOM][TFSI] at various temperature and atmospheric pressure states through conductivity, viscosity, and self-diffusion coefficient characterizations. Based on the Walden rule, the α values of neat [MorMEOM][TFSI] and LiTFSI-doped [MorMEOM][TFSI] estimated from the slopes of Walden plots were compared to those calculated from Ea,Λ/Ea,η. The diffusion coefficients of 1H, 19F and 7Li were determined using the PGSE-NMR method to carry out a study of the dynamics of the cations, anions, and ion pairs. All of the neat [MorMEOM][TFSI] and LiTFSI-doped [MorMEOM][TFSI] gave approximately straight lines for change in the D with Tη−1, demonstrating that the Stokes-Einstein equation holds for the ionic diffusivity in the ILs.