Characteristics of Electrode Overpotential over Doped Bismuth Oxide Solid Electrolyte

Abstract

The behavior of Ag, Pt, and electrodes over was studied by means of a current interruption method in the temperature range of 900–1073 K and in the oxygen pressure range of 10–105Pa. An analysis model considering that the charge transfer process is affected by the mass‐transfer process through the change of oxygen concentration was proposed and utilized for the analysis of electrode behavior. The electrode resistance of noble metals was approximately proportional to , suggesting that the rate‐determining step is the diffusion process of dissociatively adsorbed oxygen. The electrode resistance of Ag paste was dependent on the electric conductivity of the electrolyte. As for the oxide electrodes, the dependence of the resistance on the oxygen pressure was varied from order at lower temperatures to −1/2th at higher temperatures. It was analyzed that both the charge transfer and diffusion processes are rate controlling, and that the degree of contribution of each process changes with temperature. The resistance due to the diffusion process decreased with Sr concentration. The simulation based on the proposed model agreed well with experimental results in the wide range of current density.