Ionic interactions and transport mechanism in polyurethane electrolytes

Alternating current (AC) impedance, Fourier transform (FT)-Raman, and Fouri er transform infrared (FTIR) have been conducted on solutions of poly(ethyl ene oxide)((MW=1000))-urethane electrolytes commingled with LiCF3SO3 as the function of temperature and salt concentration. From the analysis of the V s(SO3) vibration, the ionic concentration of salt in various chemical envir onments can be calculated approximately. The spectroscopic evidence was fou nd for the redissociated ion pairs, and ionic congeries increased with incr easing temperature. AC impedance measurements is used to calculate the ioni c diffusion coefficient (D-i). Investigated the various concentrations (fro m O/Li = 4 similar to 20) at the different temperature (40 similar to 120 d egreesC), We found that the calculated values (D-i) with the Nernst-Einstei n equation are higher than the direct measurement. The discrepancy increase s with the increase of temperature. A good correlation between the conducti vity and the ionic redissociation is determined from the Vs(SO3) vibration band. The fraction of the "free" ion significantly corresponds to the revis ed Nernst-Einstein equation by using the Nernst-Einstein relation and compa red with those direct measurement. (C) 2002 John Wiley & Sons, Inc. J Appl Polym Sci 83: 785-790, 2002.