Synthesis and characterization of composite polymeric membranes for proton exchange membrane (PEM) fuel cell applications

This thesis presents the synthesis and characterization of novel composite membranes for medium temperature proton exchange membrane (PEM) fuel cells. Novel solid proton conductors have been prepared and characterized prior to the development of composite membranes. Two sole new classes of solid proton conductors are prepared from the incorporation of heteropolyacids onto Y-zeolite and MCM41 separately. Proton conductivities of solids are measured using impedance spectroscopy (IS) technique. These solids are also characterized using FTIR, XRD and SEM techniques.; Composite membranes are prepared by blending various weight percentages of these solid proton conductors into sulfonated polyether ether ketone (SPEEK) polymer matrix. Proton conductivities as well as water uptakes were measured for the prepared membranes. The membranes are found to be highly proton conductive at room temperature and demonstrate appreciably high values at high temperatures (up to 140°C). Highest conductivities of the order of 10-2 S/cm are measured for these composite membranes. The prepared composite membranes are also characterized using FTIR, XRD and SEM techniques. Characterization techniques confirmed uniform loading of solid inorganic material into the polymer matrix. Hence, these proposed membranes have the potential to be considered as candidates for medium temperature fuel cell applications.