Evaluating the effective diffusion coefficient of reactant gas in the catalyst layer of PEMFC using the fractal method considering the pore size distribution

Abstract

The pore size distribution of the catalyst layer (CL) significantly influences the effective diffusion coefficient (EDC) of the reactant gas due to the Knudsen diffusion effect in the proton exchange membrane fuel cell (PEMFC). In this study, a novel fractal method is proposed to evaluate the Knudsen diffusion based on the pore size distribution of the CL, which is then incorporated in the calculation of the EDC of oxygen in the CL. It suggests that the EDC of oxygen obtained from the proposed method considering the pore size distribution is greatly smaller than that obtained from the conventional Bruggeman correlation, hence resulting in much smaller maximum current density of PEMFC.