Proton Conductivity Studies on Biopolymer Electrolytes

Proton conducting solid biopolymer electrolyte membranes consisting of methyl cellulose (MC) and different wt.% of ammonium nitrate (NH4NO3) were prepared by solution cast technique. Impedance spectroscopy was carried out to study electrical characteristics of bulk materials. The ionic conductivity of the prepared samples was calculated using the bulk resistance (Rb) obtained from impedance spectroscopy plot. The highest ionic conductivity obtained was 1.17x10-4 Scm-1 for the sample with composition ratio of MC(50): NH4NO3(50). To enhance the ionic conductivity, propylene carbonate (PC) and ethylene carbonate (EC) plasticizers were introduced. It was found that the ionic conductivity of polymer electrolyte membranes increased with the increase in plasticizers concentration. The ionic conductivities of solid polymer electrolytes based on MC-NH4NO3-PC was enhanced up to 4.91x10-3 Scm-1 while for the MC-NH4NO3-EC system, the highest conductivity was 1.74x10-2 Scm-1. The addition of more plasticizer however decreases in mechanical stability of the membranes.