Ionic conductivity and association studies of novel RTMS electrolyte based on LiTFSI and acetamide

A novel room-temperature molten salt (RTMS) electrolyte based on lithium bis(trifluoromethane sulfone) imide [LiN(SO2CF3)(2), LiTFSI] and acetamide has been prepared and investigated by ac impedance, nuclear magnetic resonance (NMR), Fourier transform infrared, and Raman spectroscopy. The ionic conductivity of the (acetamide)(n) . LiTFSI complex for n = 6 reaches 1.20 x 10(-3) S/cm at 25 degreesC and rises to 5.73 x 10(-3) S/cm at 60 degreesC. The behavior of ion transport obeys well the empirical Vogel-Tamman-Fulcher type relationship for the RTMS electrolyte. Strong cation-solvent interaction has been clarified by the variation of Li-7 NMR chemical shifts and the spectral evolution of the C = O group in the (acetamide)(n) . LiTFSI complex system. The effect of salt concentration and temperature upon the ionic association has also been investigated. It is found that ionic association increases with the increases of salt concentration and temperature in the RTMS electrolyte. (C) 2004 The Electrochemical Society.