Optimization study of an agglomerate model for platinum reduction and performance in PEM fuel cell cathode

Several experimental studies on optimizing the amount of platinum loading and ionomer content in the proton exchange membrane fuel cell catalyst layers exist in the literature. In the recent years, numerical studies have also been carried out with the same objective. The amount of current generated within the catalyst layer strongly depends on the local conditions such as the concentration of available oxygen, total surface area available for reaction, and the amount of ionomer. In this study, we present two different optimization formulations: (1) for minimizing the amount of platinum, and (2) maximizing the current generated. Optimization studies are performed for all the points on the base case i-v curve, one at a time. In addition, a third formulation is also presented, in which the current is maximized simultaneously for all the i-v points. With the results of the third formulation we highlight the presence of local optima and the multi-objective nature of the fuel cell catalyst design problem. The optimization formulations are presented using a spherical agglomerate steady state model. A measure based on the platinum usage is used as a benchmark while analysing the results. Finally, we present a discussion on how these formulations can be scaled for the case of complete cathode or PEM fuel cell model. This study demonstrates that there is significant potential for reduction in platinum usage even at the smallest scales in the electrodes of a fuel cell.