Analysis of Electric Generation Distribution on a PEFC Electrode (2nd Report, Electric Generation Distribution on a PEFC with Ribs and Flow Channels of 2 mm Width)

We have separately evaluated the contact resistance, and the charge and mass transfer resistances under the channel and rib of the cathode separator in a polymer electrolyte fuel cell (PEFC) from the change of the overpotentials by removing the gas diffusion layer (GDL) under the channel. As a result, we find the ratios of current under the rib and channel for the case of the rib having the width of 2 mm. In contrast to the case of the rib having the width of 1 mm in our previous paper, the current ratios of them are almost the same when air is supplied into the cathode because the mass transfer resistance under the rib is large in the present case. On the other hand, when pure oxygen is supplied to decrease the mass transfer resistance under the rib, 80-90% of the current is generated under the rib as the case of the rib of 1 mm width. Thus the contribution of the mass transfer resistance to the current that is equivalent to the reaction rate becomes large under the rib as the width of the rib increases. The contact resistance is also found to largely contribute to the reaction rate under the channel.