Impedance Analysis of the Anodic Reaction Mechanism Using YSZ and Ba Ce_(0.8)Gd_(0.2)O_3 as the Electrolytes

摘要

Anodic reaction mechanism was investigated at the temperature range of 650～800°C using YSZ and BCG as the electrolyte, respectively. In the YSZ system, Ni-YSZ cermet was used as anode and it was found that measured impedance spectra could be separated into three different semiarcs. These three electrode resistances were identified to be the ohmic resistance in the electrode, the resistance corresponding to the formation of H_2O or diffusion of H_2O, and the resistance induced by the gas conversion, respectively. Among them, the reaction related to H_2O was found to be dominant in the electrode resistance. On the other hand, in the BCG system, Ni-BCG cermet was used as anode and the electrode reaction was also analyzed. From the comparison of the analyzed data with that for the YSZ system, the difference of electrode reaction mechanism was indicated, which was caused by the fact that BCG is a H~+/O~(2-) mixed ionic conductor.