Modeling Relaxation Processes on a Gas Electrode: Allowance for Diffusion Limitations

Abstract

The polarization behavior of a gas electrode is considered stage by stage. The consideration allows for heterogeneous electrochemical (chemical) reactions and diffusion supply (removal) of reagents and products in the near-electrode layer of electrolyte. The relaxation behavior of the electrode system is described mathematically by a set of differential equations of ordinary type and with partial derivatives. Their application on the basis of numerical modeling is illustrated with examples. For a unique quantitative measure of inertial properties of the electrode system following a change in its polarization state, it is suggested to employ, in addition to the electrical double layer capacitance and the adsorption pseudocapacitance, volume concentration pseudocapacitances of ionic and molecular electroactive forms in electrolyte. The application of mathematical expressions given for these is also illustrated by examples.