Analysis of Dominant Effects of Structure and Properties in Cathode Catalyst Layer on PEFC Performance

Abstract

Because electron, proton, and oxygen are necessary for the cathode reaction in polymer electrolyte membrane fuel cells, achieving the optimum structure of electrode catalyst layer and the efficient transport of the reactants is significantly effective to reduce the usage of Pt catalyst. In this study, we developed a three-phase boundary and a cathode catalyst layer models to clarify structures appropriate for the efficient transport, and the dominant effects of the catalyst layer structures and the properties were investigated using the models. Additionally, the evaluation equations were presented to understand the effect of structure simply, and the effectiveness was confirmed by the comparison of the results calculated by the equation and the model simulation. From the results, suitable structures of the porosity, catalyst layer and polymer electrolyte thicknesses, for the gas diffusion and proton conduction were clarified, and it was presented that the solubility of oxygen in the polymer is one of the dominant factors and increasing in the solubility is extremely effective for reduction of the Pt usage.