Abstract
Excessive water is generated when a polymer electrolyte fuel cell (PEFC) works in a high current density range. The excessive liquid water may cause clogging in the catalyst layer and gas diffusion layer (GDL), resulting in performance deterioration due to inhibition of supply of the reactant oxygen in the cathode (Flooding). As a measure to enhance the drainage of GDL, it is effective to apply a micro porous layer (MPL), which is made of carbon and water repellent PTFE (Polytetrafluoroethylene), to the GDL substrate. In this research, we focus on three dimensional porous structure analysis of the MPL by using the focused ion beam scanning electron microscope. Then, derived pore size distribution is employed to the pore network model (PNM) for convective air permeation and oxygen diffusion. Gas permeation measurements are also carried out to validate the model. The aim of this research is thereby to develop a reliable numerical model and clarify the effects of two-phase flow and water clogging on the oxygen transport in the MPL.
