engleski

Diagnostics of PEM Fuel Cell Degradation

A novel equivalent circuit model, that attempts to include the processes in the catalyst layers, represented by the two resonant loops, was applied as a tool for diagnostic of PEM fuel cell degradation. A fuel cell exposed to an accelerated stress test degraded very fast. The periodic diagnostic tests confirmed that it was the cathode catalyst layer that degraded, as intended by frequent voltage cycling. The proposed model also indicated that the cathode catalyst layer significantly degraded. The cathode catalyst layer resistance and the cathode inductance both increased several times during the accelerated degradation test, while the catalyst layer capacitance decreased by an order of magnitude. This coincides with almost 80% of the electrochemical surface area loss during the accelerated stress test, con-firmed by the polarization change curves analysis and by cyclic voltammetry. The loss of electrochemical surface area caused by the accelerated stress test was probably the result of morphological changes within the catalyst layer, which in turn resulted in increase in catalyst layer resistance and capacitance and decrease of catalyst layer capacitance. It appears that electrochemical impedance spectroscopy accompanied by the presented novel equivalent circuit model may be used for diagnostics of PEM fuel cell degradation.

Degradation ; Accelerated stress test ; Polarization change curve ; Electrochemical Impedance Spectroscopy ; Inductive loop

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