Study on hydrocarbon based electrolyte membrane by using positron annihilation spectroscopy

Abstract

  High proton conductivity is one of the desirable features for electrolyte membrane of fuel cell. In general, this depends not only on spatial structure but also electronic state relating to functional group. Positron annihilation technique seems is a powerful method to analyze such properties, since the size of open space can be measured by lifetime of positron/positronium and the electronic states can be estimated by Doppler broadening of annihilation gamma-rays which is characterized by line shape parameter, S. We have measured the electrolyte membranes composed of hydrocarbon in backbone with sulfonic group in side chain by positron annihilation technique and found that the lifetime and S were influenced by the density of sulfonic group.