Lithium ion conductive properties of aliphatic polycarbonate

Properties of polymer electrolytes composed of poly(ethylene carbonate) [PEC] and lithium bis(trifluoromethane sulfonimide) [LiTFSI, 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 LiTFSI concentration above 0.2 molar ratio of LiTFSI to repeat unit of the carbonate in PEC. Raman spectra show that the abundance ratio of undissociated LiTFSI increases at LiTFSI concentration above 0.2 molar ratio. Moreover, ionic conductivity of a PEC based polymer electrolyte increases with the increase of LiTFSI concentration above 0.2 molar ratio. The highest ionic conductivity is 0.47mScm−1 at 20°C. •The lithium ion transference number of a poly(ethylene carbonate) [PEC] based polymer electrolyte is 0.4.•Ionic conductivity of a PEC based polymer electrolyte increases with the increase of LiTFSI concentration above 0.2 molar ratio of LiTFSI to repeat unit of the carbonate in PEC.•The highest ionic conductivity is 0.47 mS cm-1 at 20°C.