(212i) Multi Catalyst Layer Modeling of a PEM Fuel Cell Cathode

The cathode catalyst layer plays an important role in the Polymer Electrolyte Membrane Fuel Cell (PEMFC) because it is the region where many limiting mechanisms occur. In the present work, multiple catalyst layers are modeled in place of a single catalyst layer to improve the cell performance, platinum utilization, and its reduction. Different values of the catalyst layer design parameters such as platinum loading, ionomer loading, and fraction of platinum on carbon are considered for different catalyst layers. Since the concentration of oxygen decreases from the diffusion layer - catalyst layer interface towards the polymer membrane due to the oxidation reaction, less void volumes are required towards the polymer membrane. Similarly, as protons are consumed in the oxidation reaction, less volume of the ionomer is required from the polymer membrane ? catalyst layer interface towards the diffusion medium. Hence, the design parameters of the catalyst layers are chosen such that the catalyst layer adjacent to the diffusion medium is of more void volume and the catalyst layer near polymer membrane contains more volume of the ionomer. The amount of platinum loading is changed from the first catalyst layer (adjacent to GDL/MPL) to the last catalyst layer (adjacent to the polymer membrane). Simulations are performed for various platinum loadings and also for various values of the design parameters in the catalyst layers throughout the polarization range. The results suggest that there exists an optimum combination of the design parameters in each catalyst layer for a better performance of the cell.