Influence of heteropolyacid in enhancing proton conductivity of chitosan membranes for H2/O2 Fuel Cells

Abstract

To promote Proton Exchange Membrane Fuel Cells (PEMFCs) commercialization, large research effort has been devoted in developing new polymer electrolytes that can replace the usually employed proton conductors, e.g. Nafion®, with other membranes of comparable performances but lower cost. Chitosan (CS)-based membrane electrolyte is currently studied as alternative candidate for PEMFC application. Several works have shown that Heteropolyacids (HPAs) can be used to prepare Chitosan polyelectrolytes (PECs) to be employed as proton exchange membrane in low temperature fuel cell. In previous works [1-3] we have shown that CS/PTA membranes, prepared using alumina porous medium for the slow release of H3PW12O40, show good performances in H2 fed fuel cell. Notably, in ref. [4] CS/PMA membranes are reported to exhibit proton conductivity higher than that measured with CS/PTA. This paper in focused on the synthesis and characterization of CS/PMA and mixed CS/PMA-PTA membranes with the aim to assess the influence of HPA concentration and nature on their performance as proton conductors in H2 fed fuel cell. X-ray diffraction and FTIR analyses were performed to study the structure and composition of the membranes, while SEM was used to get information on the membranes morphology and thickness as a function of the preparation conditions. The membranes were tested in a H2/O2 fuel cell at room temperature. Impedance Spectroscopy was used to get information of the conductivity of the membrane and to model the overall electrical behaviour of the cell.