Analysis of electric generation distribution on a PEFC electrode (3rd report, electric generation distribution in a PEFC analyzed by partial electrode method)

We have analyzed current ratios under the rib and channel of a cathode separator having 2 mm width rib and channel in a polymer electrolyte fuel cell (PEFC). Three types of membrane electrode assembly (MEA) including the one with a partial electrode (catalyst layer) only under the rib and that only under the channel in addition to the conventional MEA with the electrode on the whole area are prepared for the analysis. As a result, the ratios under the rib are found to be 60% and 40% in low and high current density regions, respectively. These results are in good agreement with that from the method of removing the gas diffusion layer (GDL) under the channel in our previous paper where IR resistance and mass transfer resistance have been assumed to be inversely proportional to the area of GDL with the assumption of constant charge transfer resistance. Both methods provide concrete guidelines for the improvement of PEFC performance. Although the partial electrode method addressed in the present paper is direct and strict way, it is complicated since the three types of MEA are necessary. The GDL removing method is, however, simple and practical.