The maxima near the cathode inlet r

The maxima near the cathode inlet result from the high amount of O2 in this region. In the regions where cathode and anode channels cross (see Fig. 3 top left),the current density is quite low. These regions have a smaller rib area and, hence, a better gas access. The latter is responsible for a dry membrane (see Fig. 9 right) due to faster H2O diffusion, and the smaller rib area hampers the electron access, i.e. D increases (see Fig. 8 right). Both effects lower the current density in these regions. The ‘S’-shaped current density minimum in the middle of the reaction layer and the higher values left and right of it are a consequence of the contact resistance distribution (see Fig. 3 top right). A low contact resistance leads to a low D and a high current density, and vice versa.