A New Fuel Cell Degradation Model Indexed by Proton Exchange Membrane Thickness Derived From Polarization Curve

This article has developed a thickness-polarization degradation model based on the experimental data and polarization curves to model the degradation process of the proton exchange membrane fuel cell (PEMFC) refereeing proton exchange membrane (PEM) thickness. The PEM thickness coupling with the PEMFC's voltage and current density changes with the aging process. In this study, the data of PEMFC's voltage and current density are obtained from the test bench under specific conditions. A new semiempirical model adopted from the classic degradation model has been reconstructed as a form of voltage changing with current density and PEM thickness. A reverse fitting approach is developed to deal with the semiempirical model to decouple the PEM thickness against operation time from the voltage and current density. As a result, the relationship between the PEM thickness and PEMFC's operation time can be described as a rational fraction with the second-order numerator and first-order denominator. In the proposed PEM thickness-polarization degradation model, the PEM thickness changing mechanism as the rational fraction is substituted into the reconstructed semiempirical model. Consequently, the time-discrete polarization curves are converted into the time-continuous form, enabling the real-time estimation of PEMFC's state of health (SoH). The derived continuous polarization curve is verified by comparing it with the experimental time-discrete polarization curves showing more than 94.4% accuracy.