Electrical conduction in solid polymer electrolytes: temperature dependence mechanism

It is generally accepted that the electrical conduction in solid polymer el ectrolytes (PE) is strongly temperature dependent: an Arrhenius dependence is observed at low temperatures, while a non-Arrhenius Vogel-Tamman-Fulcher (VTF) behavior is seen at high temperatures. A theory is introduced, for t he first time, for the electrical conduction of solid PE in the entire rang e of temperatures, by considering the fluctuation of the melting temperatur e and by the application of the statistical theory of gelation. The theory contains the expected Arrhenius and VTF dependence as the asymptotic limits at low and high temperatures, respectively. In addition, a critical transi tion temperature at which the electrical conductivity behavior changes from Arrhenius-like to VTF-like is determined analytically. This critical tempe rature is shown to increase linearly with the melting point of the PE. It i s demonstrated that the theoretical results are in good agreement with the experimental evidence. (C) 2000 Elsevier Science Ltd. All rights reserved.