(89b) Effects of the Micro-Porous Layer on Water Transport in a PEM Fuel Cell

A model was developed to evaluate the role of the micro-porous layer (MPL) and the effects of its properties on liquid water transport in the cathode of a proton exchange membrane (PEM) fuel cell. The results validated that the fuel cell performance was improved by adding a MPL between the macro-porous gas diffusion layer (GDL) and the catalyst layer (CL) in the cathode side. The MPL, due to its high hydrophobicity, increases the liquid water pressure in the cathode to the levels much higher than those in the anode resulting in an increased back-transport rate of liquid water from the cathode to the anode. The more hydrophobic the MPL is, the higher liquid pressure increases, and, consequently, the higher driving force is created across the membrane to drive water from the cathode to the anode. Higher back transport rate of water from the cathode to anode mitigates flooding in the cathode and eliminate or reduce the need for humidification in the anode.