2020 年 88 巻 1 号 p. 28-33
In this study, the applicability of Ba(Ce,Co,Y)O3−δ (BCCY) for a cathode of proton-conducting ceramic fuel cells was investigated. The electrical conductivity and transference number of BCCY were significantly affected by a cobalt content in the oxide. It was found that this material showed a mixed conduction of proton, oxide ion, and electron. The addition of cobalt into Ba(Ce,Y)O3−δ mainly increased the electronic conductivity of materials. Composite electrodes with an optimum composition of La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF)–BaCe0.7Co0.2Y0.1O3−δ (50:50 wt.%) exhibited lower polarization for the symmetrical cell test with a BaCe0.8Y0.2O3−δ electrolyte in 6.5% humidified oxygen atmosphere, as compared with La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) itself and LSCF–BaCe0.9Y0.1O3−δ (50:50 wt.%) composite electrodes. The power generation test was performed at 600°C–700°C using a BaCe0.8Y0.2O3−δ electrolyte-supported single cell employing a LSCF–BaCe0.7Co0.2Y0.1O3−δ (50:50 wt.%) composite cathode, upon feeding 3% humidified hydrogen and pure oxygen to the anode and cathode, respectively. The cell with a LSCF–BaCe0.7Co0.2Y0.1O3−δ (50:50 wt.%) composite cathode exhibited much higher performance than that with a LSCF electrode. Consequently, the introduction of cobalt into Ba(Ce,Y)O3−δ was an effective strategy for an improvement in an oxygen reduction reaction activity of a cathode material.
