Effects of Gas Diffusion Layer Porosity Distribution on Proton Exchange Membrane Fuel Cell

The effect of the porosity change of the cathode gas diffusion layer (GDL) along the cell length on the proton exchange membrane fuel cell (PEMFC) is evaluated using the calculation model and the numerical method. A detailed analysis of the polarization curve, temperature distribution of the cell center surface, cathode material, and current distribution law is carried out for six different porosity models. It is found that the influence of the GDL porosity on the fuel cell polarization curve increases with the increase in current density, and the influence reaches the maximum at the limit current density. The limit current of the fuel cell is directly proportional to the GDL porosity, and the change of GDL porosity has limited influence on it. The existence of the porosity gradient improves the uniformity of the material and current density distribution on the cathode side. The same conclusion can be obtained using the standard deviation formula to quantitatively express the degree of uniformity. The results show that the existence of the GDL porosity gradient of the PEMFC cathode has a positive effect on the cell performance.