The effect of micro-porous layers on the performance of proton exchange membrane fuel cells

Abstract

Micro-porous layers (MPLs) of varying porosities were prepared on wet-proof carbon paper in order to investigate the effect of porosity on proton exchange membrane fuel cells. Pore size distribution in the gas diffusion electrode (GDE) layer was shown to have a bimodal distribution at approximately 0.01 and 0.08 μm. It appears that the smaller pores transfer gas and the larger pores remove water by capillary action. An appropriate amount of NH4Cl (50 wt%) in the MPL can therefore improve fuel cell performance because an optimum compromise can be found between water—gas transfer and internal resistance. Further increasing the NH4Cl content and porosity does not improve performance because internal resistance rises.