Oxygen mass transfer in PEM fuel cell gas diffusion layers

A simple two-dimensional model involving kinetics and mass transfer in a PEM fuel cell cathode is presented. In this model, the catalyst layer was simplified as an infinite thin film. The oxygen mass transfer in the gas diffusion layer (GDL) was described using a pure diffusion equation that introduced equivalent oxygen diffusivity. The PEM fuel cell performance under the influence of current collector ribs was investigated. The results show that, the existence of ribs causes the GDL to be used only partly in the mass transfer process. The GDL effectiveness decreases with the cell current density and increases with the width of the gas flow channels. The PEM fuel cell performance decreases with an increase in GDL thickness if the GDL porosity is low. However, when a high-porosity GDL is used, the optimal thickness becomes an indicator determining the maximal PEM fuel cell performance. (C) 2004 Elsevier B.V. All rights reserved.