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Electrochemical Impedance Spectroscopy as a Diagnostic Tool for High-Temperature PEM Fuel Cells
One such basic tool is electrochemical impedance spectroscopy (EIS). The technique is highly versatile, and instruments are widely available in electrochemistry laboratories. Here we present the capability of EIS to analyse the performance of high-temperature MEAs for optimizing their composition and material selection. We investigated MEAs with various commercial catalysts, PTFE contents, acid doping levels, and acid base blend membranes. Polarization curves and impedance spectra were taken for all these individual cases. Depending on the operating condition and the MEA design, up to three semi-circles were observed in the HT-PEMFC Nyquist plot, which allows us to resolve the individual cell overpotentials due to membrane resistivity, hydrogen oxidation, oxygen reduction, and mass transport. Such rich information acquired with EIS helps reveal the underlying processes occurring in the MEA during fuel cell operation, which is essential for MEA design and optimization.