Electrochemical Impedance Spectroscopy of Proton Exchange Membrane Fuel Cells (PEMFC) using Embedded Probes

Three cast Nafion membranes were laminated with two silver mesh (screens) to form proton exchange membrane fuel cells (PEMFC) with embedded reference electrodes. Performance characteristics of the PEMFC were evaluated at 80 degrees C with humidified (100% RH) H-2 and air or O-2 as fuel and oxidant respectively. Impedance spectra were obtained between the cathode and the anode, between the reference electrodes and the cathode, between the reference electrodes and the anode, and across the reference electrodes under various loads. DC voltage between the reference electrodes and the cathode and the anode were also measured at various loads. Individual electrode polarizations were obtained from impedance spectra. The results showed that cathode polarization was greater than anode polarization. Also, the cathode exhibited significant concentration polarization.