Transient behavior in porous electrodes during reactant depletion

An experimental system and theoretical model have been developed in order to study in a detailed manner the significance of the depletion of reactive material in affecting the transient discharge behavior of porous electrodes. Depletion phenomena have been studied for the potentiostatic and galvanostatic discharge of a stainless steel, single pore, sectioned electrode which had been plated with a finite amount of copper. The currents passing to the individual electrode sections were measured as a function of time during discharge. The electrolyte was a dilute solution of copper sulfate supported by sulfuric acid. The theoretical model employs the pseudohomogeneous one-dimensional assumption. Both diffusional and migrational transport are taken into account, and a kinetic expression of the Butler-Volmer form is employed.