Potential cycle tests that simulate the operation of a fuel cell vehicle are widely adopted as a durability testing method of membrane-electrode assemblies (MEAs). The Fuel Cell Commercialization Conference of Japan (FCCJ) has proposed methodologies for testing MEAs and their materials in 2007, focusing on the evaluation of the durability of electrode materials. The two protocols, start/stop durability test and load cycle durability test, were revised in 2011 based on the up-to-date knowledge concerning fuel cell durability. In this study, we applied the revised protocols to a standard electrocatalyst, and the effect of the revision was verified. We have demonstrated that the revision of the protocols accelerates the evaluation of fuel cell materials and verified that the revised protocols effectively separate the degradation of Pt electrocatalyst from that of carbon support.

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Hydrogen for fuel cell vehicles is likely to contain impurities from its production process, and such impurities may poison the fuel cell catalyst, which in turn will deteriorate the power generation performance of the fuel cell especially when the Pt loading is reduced. Effects of anode Pt loading and CO as an impurity on power generation performance were investigated. The test results indicated that the smaller the Pt loading in the anode was, the more rapidly cell voltage declined under the influence of CO contained in the hydrogen. The amount of voltage decrease accelerated as the Pt loading was reduced. With regard to CO and CO 2 concentrations in exhaust gas, it was found that when the cell voltage fell and stabilized following the supply of a CO-added hydrogen, a reduction of Pt loading resulted in the lowering of CO concentration and the heightening of CO 2 concentration.

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Single-cell test and exhaust gas analysis were conducted to determine the effect of NH3 in hydrogen fuel on the performance of polymer electrolyte membrane fuel cells. To prevent nitrogen from air mixing with the exhaust gas, 50 ppm NH3 in hydrogen was supplied to the anode, and a mixture of O2 (21%) and Ar (79%) instead of air was supplied to the cathode. The cell was operated under a current density of 1000 mA/cm2 at 80 °C. Ion chromatography, Fourier transform infrared spectroscopy, and quadrupole mass spectroscopy were performed to analyze the exhaust gas from the anode and cathode. Analysis revealed that most of the NH3 supplied to the anode migrated to the cathode and was emitted as NH4+, N2, N2O, and NO. This result indicates that nitrogen-containing compounds that migrate from the anode to the cathode may affect the oxygen reduction reaction of the cathode.

The membrane electrode assembly (MEA) durability test protocols proposed by FCCJ, USFCC and DOE were compared in their deterioration behavior of performances and materials. These MEA durability tests for polymer electrolyte fuel cells were performed using JARI's standard single cell. In the carbon support corrosion test protocols, carbon decomposition (oxidation), collapsing of the porous structure of the carbon support, and agglomeration and dropout of the platinum (Pt) catalyst were observed. A proper fast evaluation can be done by the FCCJ protocol because of the highest applied voltage. In the Pt catalyst stability test protocols, both Pt particle growth and also carbon oxidation were observed in the Pt/C catalyst used in this study. It was found that the carbon oxidation rate was the lowest in the DOE protocol. In the membrane durability test protocols, decomposed fluorine F-and thinning of membrane were observed. Tests results suggest that the FCCJ protocol (using air, without pressure difference between anode and cathode) was the best at early stage evaluation.

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