Ionic interactions and transport mechanism in polyurethane electrolytes

Alternating current (AC) impedance, Fourier transform (FT)–Raman, and Fourier transform infrared (FTIR) have been conducted on solutions of poly(ethylene oxide)_(MW=1000)–urethane electrolytes commingled with LiCF₃SO₃ as the function of temperature and salt concentration. From the analysis of the Vs(SO₃) vibration, the ionic concentration of salt in various chemical environments can be calculated approximately. The spectroscopic evidence was found for the redissociated ion pairs, and ionic congeries increased with increasing temperature. AC impedance measurements is used to calculate the ionic diffusion coefficient (D_i). Investigated the various concentrations (from O/Li = 4 ～ 20) at the different temperature (40 ～ 120°C), We found that the calculated values (D_i) with the Nernst–Einstein equation are higher than the direct measurement. The discrepancy increases with the increase of temperature. A good correlation between the conductivity and the ionic redissociation is determined from the Vs(SO₃) vibration band. The fraction of the “free” ion significantly corresponds to the revised Nernst–Einstein equation by using the Nernst–Einstein relation and compared with those direct measurement. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 785–790, 2002