MODELING THE MODE OF OPERATION OF PEMFC ELECTRODES AT THE PARTICLE LEVEL - INFLUENCE OF OHMIC DROP WITHIN THE ACTIVE LAYER ON ELECTRODE PERFORMANCE

Numerical modelling of charge transfer using the finite element method within the whole active layer of proton exchange membrane fuel cell ( PEMFC) electrodes is proposed in order to study the electrocatalyst ut ilization as characterized by the effectiveness factor. In this way, t wo modified approaches based on the thin film and agglomerate models a re developed for studying ionic ohmic drop effects in the active layer at both the electrolyte layer and electrocatalyst particles scales. T he catalyst phase is considered to be a network of spherical nanoparti cles instead of the classical representation as a uniform distribution over a surface (thin film model) or in a volume (agglomerate model). Simulations point out unexpected effects at the local level due to the discrete distribution of the catalyst phase as nanoparticles. Finally , the results are applied to the practical case of oxygen reduction an d hydrogen oxidation.