| Solvent cast porous electrodes made of conductive catalytic carbon and thermoplastic polymer blends and polyphosphonate proton transfer membranes for polymer electrolyte membrane (PEM) fuel cell have been developed and studied. Fundamental characteristics of these components and their electrochemical performances are reported. Phase inversion technique was employed to produce novel porous fuel cell electrodes with controlled morphology. The influence of the structure on: both electrochemical active layer and gas diffusion layer of the electrode, as well as the catalyst distribution were extensively studied. Electron Microscopy techniques were used to reveal the relationship between structural parameters and electrochemical performance. This study suggests that the gases accessibility to the maximum number of the reaction sites, that have both ionic and electronic conductivity, determine the electrode efficiency. Carbons with different sizes and surface properties were studied. Carbon blends were utilized to alter the structure and surface properties of the electrodes. A current of greater than 600 mA/cm{dollar}sp2{dollar} at 500 mV, {dollar}50spcircrm C,{dollar} {dollar}{lcub}sim{rcub}1{dollar} atm (atmospheric pressure) with Pt catalyst surface concentration of electrode {dollar}{lcub}sim{rcub}0.1{dollar} mg/cm{dollar}sp2{dollar} was generated in fuel cell with this porous electrode. Thermal properties of carbon/polymer blends were also studied. The crystallization behavior of polyvinylidene fluoride and glass transition temperature of polysulfone in presence of carbon were examined. The results of this study suggest that carbon has significant impact on the structure and thermal properties of these thermoplastic polymers. The relevant properties of poly(dimethyl phenylene oxide phosphonic acid) ion exchange membrane {dollar}rm (PPOPsb{lcub}n{rcub}H),{dollar} such as ionic conductivity, water content, ion charge density, dependence of temperature, and thermal stability, have been evaluated in this study. The {dollar}rm PPOPsb{lcub}n{rcub}H{dollar} membranes display a good stability at the elevated temperature {dollar}({lcub}sim{rcub}150spcircrm C).{dollar} These membranes were tested in PEM fuel cell at low temperature {dollar}({lcub}<{rcub}100spcircrm C).{dollar} Preliminary results suggest that the {dollar}rm PPOPsb{lcub}n{rcub}H{dollar} can be a good candidate as a proton transfer membrane for the PEM fuel cell. |
