Properties of polymer electrolytes composed of poly( ethylene carbonate) [PEC] and lithium bis(trifluoromethane sulfonimide) [LiTESI, LiN(CF3SO2)(2)] have been analyzed using Raman spectroscopy, dynamic mechanical analysis (DMA) measurements, and ac impedance spectroscopy. The lithium ion transference number of a PEC based polymer electrolyte is 0.4, which is 4 times higher than that of a poly(ethylene oxide)[PEO] based polymer electrolyte. The glass transition temperature of a PEC based polymer electrolyte decreases with the increase of LiTESI concentration above 0.2 molar ratio of LiTESI to repeat unit of the carbonate in PEC. Raman spectra show that the abundance ratio of undissociated LiTESI increases at LiTESI concentration above 0.2 molar ratio. Moreover, ionic conductivity of a PEC based polymer electrolyte increases with the increase of LiTESI concentration above 0.2 molar ratio. The highest ionic conductivity is 0.47 mS cm(-1) at 20 degrees C. (C) 2014 Elsevier B.V. All rights reserved.