(35g) The Relation Between Ink Agglomerate Size and Pore Size Distribution of the Cathode Catalyst Layer of PEM Fuel Cells and the Effect of Carbon Corrosion on CCL Structure

Carbon corrosion is a major degradation mechanism in cathode catalyst layers (CCL) of polymer electrolyte membrane (PEM) fuel cells. Carbon corrosion (coupled with ionomer dissolution/degradation) induces severe changes in the CCL structure. In the present study, the inter-relation between the particle size of a packed sphere medium and the pore size distribution (PSD) is established. This relation is then used to predict the agglomerate size of the mix of Pt/C and ionomer in the catalyst ink, using experimentally measured PSD of the CCL. During cell degradation, the size of these agglomerates decreases; since, carbon corrosion causes carbon particles to decrease in size. Furthermore, as carbon corrosion proceeds, the ionomer to carbon ratio of agglomerates increase. Literature data suggests that as the ionomer to carbon ratio of the ink increases, the pore sizes and the porosity of the CCL decrease. These data are implemented in the present work to predict the PSD of the CCL at any given state of carbon corrosion.