Segmented thermoplastic polyurethane (TPU) was synthesized from methylene bis(cyclohexyl isocyanate) (H 12 MDI), ethylenediamine (EDA), and poly(propylene glycol) (PPG) with a molecular weight of 1000. The ratio of hard segment to soft segment (NCO/OH) is changed to test the chemical and physical properties. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and impedance spectroscopy (IS) were utilized to monitor the phase change of these TPU samples with various lithium perchlorate (LiClO 4 ) concentrations. Significant changes occur in the FTIR spectrum of the TPU with LiClO 4 concentration above 0.5 mmol/g TPU, indicating that an interaction existed between the lithium cation and the hard segment or soft phase. The soft-segment T g increased with increasing LiClO 4 concentration through the examination of DSC. IS results indicate an increase in bulk conductivity as the salt concentration is increased. Electrochemical stability of the TPU sample was studied by cyclic votammetry (CV).