| Water-Free Proton-Conducting Membranes for Fuel Cells |
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| NASA’s Jet Propulsion Laboratory, Pasadena, California | |
| Jun 30 2007 | |
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Each of these preparations was brushed onto an open mat of glass fibers. The coated mats were dried in flowing air at a temperature of 60 °C for about an hour. The coated mats were further dried in a vacuum oven at 60 °C to remove traces of water. The thermal stability of P4VPBS was evaluated by differential scanning calorimetry. The results showed that P4VPBS undergoes a glass transition at a temperature of about 182 °C and that it melts at about 298.7 °C, with no evidence of decomposition. These thermal properties are consistent with the requirements for stability under operating conditions in fuel cells.
 Cell Potential vs. Current Density was measured in a test of an experimental membrane/electrode assembly in a hydrogen/oxygen fuel cell at a temperature of 183.5 °C. In preparation for the tests of fuel-cell performance, the coated mats were further coated with catalytic anode and cathode layers to form membrane/electrode assemblies. No attempt was made to optimize the catalytic layers. In the fuel-cell tests, stable maximum cell potentials of 0.85 V were attained. The anticipated maximum cell voltage was 1.0 V. The decrease from the expected maximum value was attributed to some crossover of hydrogen and oxygen through the membranes. The figure shows some of the data from the fuel-cell test of the mat coated with the P4VPBS/silica composite. The power density indicated by these data is low for a fuel cell operating at the indicated temperature — presumably because of the lack of optimization of the catalyst layers. Nevertheless, the data suggest that optimization of catalysts and enhancement of conductivity should make it possible to realize high-temperature fuel cells. This work was done by Sekharipuram Narayanan and Shiao-Pin Yen of Caltech for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Materials category.
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Water-Free Proton-Conducting Membranes for Fuel Cells (reference NPO-30873) is currently available for download from the TSP library. Login first to download.
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