Impedance and dielectric spectroscopy of polymer electrolyte membranes

This thesis deals with the investigation of the proton conductivity in the polymer electrolyte membranes (PEMs) using electrochemical impedance spectroscopy and broadband dielectric spectroscopy (BDS). A variety of parameters viz. testing method (through-plane, in-plane), electrode configuration (2-probe, 4-probe), ac amplitude, frequency range, etc. were optimized to get standard impedance spectral features for extracting the true conductivity of the membranes. BDS was used to investigate the polymer chain dynamics at high temperatures under an applied potential and the consequent effects on the proton conductivity; Nafion-117, sulfonated polysulfone, sulfonated polyetherketone and phosphoric acid-doped poly(2,5-benzimidazole) membranes were used for the above mentioned studies. Thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy of the Indian Institute of Technology Bombay, India and Monash University, Australia.