The Effect of the Reference Electrode Position on the Measurement of Half Cell Polarization in Proton-Exchange Membrane Fuel Cells

In this experimental and numerical study we analyze the polarization of the electrodes in a PEM fuel cell system. In order to measure the anode and cathode potential with respect to the electrolyte potential, a dynamic hydrogen electrode (DHE) is used as reference electrode. Two fundamental configurations for integrating a DHE into the membrane electrode assembly (MEA) are investigated: In the first configuration, the DHE is contacted to the membrane within a circular gap in the cathode catalyst layer, which is called edge configuration. In the second configuration, the DHE is placed between two membrane layers, which is called sandwich configuration. Differences between the reference electrode setups can be ascribed to an inhomogeneous electrolyte potential distribution close to the edge of the electrodes as described in literature. Our 2D fuel cell model as published in an earlier article is used to investigate this effect. We show that it is not possible to detect the electrode polarization by use of a reference electrode in edge configuration. By use of the sandwich configuration, the polarization of the anode and cathode half cells can be measured independently.