On the distribution of current generation in porous gas electrodes

Abstract

In the active layer of porous gas electrodes, the spatial distribution of energy generation is determined by several interacting factors, e.g. pore statistics, distribution of active sites, and a set of correlated transport equations. After a short introduction to the problem, it is shown that the transport phenomena can, in this case, be treated in a very simplified manner. In particular, the specific electron resistance can be neglected. Restriction of gas supply can be described by a formalistic gas resistanceρ _g. Thus, the interaction of the different transport parameters can be treated by considering purely electrical models. The relative magnitudes of the different parameters, in the case under study, are of such an order that finally it is only necessary to consider two of them: the specific ionic resistivity of the porous electrode filled partly with liquid electrolyte, and a special parameterp which describes the overvoltage in the region between gaseous phase and electrolyte. As a result, the spatial distribution of current generation can be indicated in the form of analytical expressions and diagrams. One also obtains values of the penetration depth of current generation which do not disagree with practical experience.