THE SIMPLE-PORE AND THIN-FILM MODELS OF POROUS GAS DIFFUSION ELECTRODES.
Rept. no. 7,
PENNSYLVANIA STATE UNIV UNIVERSITY PARK MINERAL INDUSTRIES EXPERIMENT STATION
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Two physical models for the mode of operation of porous gas diffusion electrodes for fuel cells are discussed. For nonwetted electrodes the simple-pore model is proposed, in which reactant gas dissolves in electrolyte and diffuses to the submerged electrode surface near the three phase boundary of solid-liquid-gas. It is shown that for normal gas solubilities and diffusion coefficients, this model will lead to low mass transport limited currents unless the pore diameter is less than about 1 micron. For wetted double-layer structure electrodes the thin-film model appears reasonable on the basis of experimental observation. An approximate mathematical treatment of this model leads to useful simple solutions, which can form the basis for design of experiments to test the model. Author