MODIFIED FLOODED SPHERICAL AGGLOMERATE MODEL FOR GAS-DIFFUSION ELECTRODES IN ALKALINE FUEL-CELLS

The spherical-grain mathematical model is modified and tested against experimental data for single-layer, gas-diffusion electrodes of alkali ne fuel cells. The model assumes that the electrode is made of spheric al agglomerates of Raney metal and polytetrafluoroethylene (PTFE) that are flooded with electrolyte; the gas occupies the macropores of the electrode. In addition to previous analysis of the diffusion and react ion in the grains, the modified model includes the resistance of gas d iffusion into the macropores and a thin electrolyte film surrounding t he grain. The original model and the modified model are both compared with experimental polarization data for hydrogen oxidation on an Ni/PT FE electrode in alkaline electrolyte. The newly developed model predic ts accurately the experimental data in all regions.