Influence of the Microstructure of the Catalyst Layer on the Performance of the PEMFC Cathode
E. Fontes, J. Schumacher, N. Vasileiades, O. Parhammar and A. Schmitz
COMSOL Inc., US
Keywords: fuel cells, modeling, agglomerate model, current distribution
This paper presents a model of a unit cell of a PEMFC for applications in portable electronic devices. The model introduces the transport resistance exerted by the electrolyte confined in the active layer using a filmed agglomerate model [1,2]. Several publications have used the agglomerate model for description of the microstructure in the active layer but non of these have implemented it in a two- or three-dimensional model of a PEMFC unit cell.
The agglomerate model is used to describe the transport resistance between the gas phase and the catalyst particles in the active layer. It assumes that the local current density on the surface of the active layer is given by a Tafel expression and that oxygen has to dissolve in the electrolyte and diffuse to the active sites before a reaction can take place. The fuel cell model couples the electronic potential and ionic potential to the mass balances of water, oxygen and nitrogen, at the cathode. The anode is described by the electronic and ionic potentials in combination with the mass balances for water and hydrogen. The mass and current balances are coupled through the kinetic expression in the active layer, both at the anode and cathode.
NSTI Nanotech 2003 Conference Technical Program Abstract