The influence of dynamic load changes on temporary impedance in hydrogen fuel cells, selection and Validation of the electrical equivalent circuit

Kurzfassung

To achieve optimal performance of a fuel cell, a reliable monitoring and diagnostic method is required. The currently utilized methods give limited information or they are impossible to use under dynamic working conditions. To obtain comprehensive information about the fuel cell operation we utilized novel dynamic electrochemical impedance spectroscopy. Impedance measurements in dynamic mode were performed on a hydrogen fuel cell, working under various conditions. By utilizing this new methodology, optimum Parameters for cell operation were determined. An electrical equivalent circuit for cathodic processes was determined. Presence of an interlayer, between the membrane and the catalytic layer, was postulated. The instantaneous impedance spectra were analysed under the function of current load. The complete character of the impedance spectra was revealed, and the electrical equivalent circuit was validated. The presence of the interlayer was established by impedance analysis and by a profile of platinum content changes in the Membrane electrode assembly. The proposed Investigation methodology provides monitoring and diagnostics of fuel cell components, which gives the possibility of streamlined management of the fuel cell operation.