Evaluating the role of oxygen adsorption in the detection of local oxygen starvation conditions in proton-exchange membrane fuel cells

Abstract

One of the key challenges in fuel cell systems control is avoiding local oxygen starvation, which can lead to the degradation of the catalyst layer. Reduced-order model-based control strategies can help to detect this situation and apply corrective measures in terms of working pressure or stoichiometry in the cathode stream. One of the challenges for reduced-order models is to capture the kinetic performance of the oxygen reduction reaction at oxygen limited conditions, where adsorption coverage can play a significant role. This study aims to investigate the role of incorporating oxygen adsorption in the catalyst layer on the performance of a previously developed control-oriented model under low oxygen conditions. For this purpose, a linearized version of the Frumkin adsorption isotherm is adapted and incorporated into the model. The updated model is validated against local current density distribution data at different cathode stoichiometries, extracted from the literature. The results highlight the importance of capturing the oxygen coverage in the catalyst layer to properly capture the aggressive deterioration of electrochemical performance in the last portion of the cell under oxygen-limited conditions. Finally, an example of the usage of the model in a real driving cycle to optimize cathode stoichiometry in transient conditions is presented.