Investigation into the gas diffusion electrodes of polymer electrolyte membrane fuel cell under long-term durability test

When the polymer electrolyte membrane fuel cell is operated for a long period of time, there is a change in the material composition of the membrane electrode assembly (MEA) that coincides with progressive deterioration of the cell. Therefore, it is important to analyze the change in MEA composition. In this study, the durability of a fuel cell was examined during a period of 12 000 h. These test cells were disassembled one after another, approximately every 3000 h, and the change in the constituent was analyzed in detail on the view point of the material and structure. The change in the constituent with MEA in relation with the operating time was also analyzed in detail. The relationship between the changes in the constituent and the operating time was examined and clarified. These changes were in the porosity of the electrode, in the pore distribution of the electrode, and in the surface area of the electrode. Moreover, the change in the thickness of the electrolyte membrane and the change in the material of ionomer on the electrode catalyst were analyzed. In the analysis, transmission electron microscopy, scanning electron microscopy, electron probe microanalysis, and mercury porosimetry were used. As a result, structural changes in the electrodes were quantitatively clarified in relation to an elapsing of operating time. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3328051]