A novel equivalent circuit model is made by adding additional resonance loops comprising of a resistance, capacitance and inductance, for both anode and cathode, representing mass transport and resistive losses within the catalyst layer. Such a model is able to match and explain low frequency inductance observed in all Electrochemical Impedance Spectroscopy measurements taken during durability tests. The model was used to monitor the state of health of a fuel cell exposed to a controlled

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... ated stress test. The results indicate that resistance, capacitance and inductance representing the cathode catalyst layer change dramatically during the accelerated stress test, and this shows good agreement with the findings of the periodic diagnostic tests.