The ionic conductivity, translational diffusion, molecular motion, and physicochemical properties of ionic liquids (ILs) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-doped ILs with two different imidazolium cations (1-methyl-3-pentylimidazolium [MPI]+ and 1,2-dimethyl-3-pentyl-imidazolium [DMPI]+) are characterized. Self-diffusion coefficients D for the anion and the cation are measured by pulsed field gradient spin echo NMR (PGSE-NMR), the measured ion diffusion coefficients, viscosities, and ionic conductivity follow the Vogel-Tammann-Fulcher (VTF) equation for the temperature dependencies, and the best-fit parameters are determined. LiTFSI-doped [MPI][TFSI] shows a NOE signal between Li+ and MPI+ and a broad Li peak was observed in HOESY spectra, whereas there is no NOE signal in LiTFSI-doped [DMPI][TFSI], demonstrating that one additional methyl group at the C-2 position in the DMPI+ may prevent Li+ to be closed to DMPI+ via steric hindrance.
|Number of pages||18|
|Journal||International Journal of Electrochemical Science|
|Publication status||Published - 2013 Jun|
All Science Journal Classification (ASJC) codes