Effect of Pore Structure on Current and Potential Distributions in a Porous Electrode

The effects of the detailed structure of porous electrodes on their macroscopic and microscopic current and potential distributions have been quantitatively analyzed. An analytical expression has been derived for the macroscopic pore resistance in terms of a constriction factor which can be related to the pore microstructure and takes the place of an empirical tortuosity. The model has been verified by comparing its predictions to results from numerical computations and experiment. Analysis of the current and concentration distributions within localized micropores indicates that the microporous area is fully accessible to charge and mass transfer. Thus the kinetics of interfacial processes is determined primarily by the micropore structure, while the ohmic and mass transport limitations throughout the volume of the electrode are imposed principally by the resistance of the macropores.