Analysis of Cathode Catalyst Layer Structure and Oxygen Transport Resistance Depending on Fabrication Condition in PEFC

摘要

For efficient use of Pt catalyst in polymer electrolyte membrane fuel cells (PEFCs), the effects of the cathode catalyst layer (CL) structure on the cell performance were evaluated experimentally. In particular we focused on two parameters used in analysis by agglomerate models, the agglomerate size and the oxygen dissolution resistance to the ionomer surrounding the carbon agglomerate. Various ratios of ionomer to carbon were selected as the CL fabrication condition with same amount of Pt-supported carbon. To estimate the agglomerate size, pore size distribution (PSD) was measured by nitrogen physisorption method, and an estimation method of agglomerate size distribution from the measured PSD was applied. It was shown that the model analysis using the estimated parameters with relatively-small agglomerate size can well simulate the measured IV characteristics, and that the balance of the oxygen diffusion and dissolution resistances in the ionomer dominates the cell performance under the condition here.