La0.6Ba0.4CoO3 as a cathode material for solid oxide fuel cells using a BaCeO3 electrolyte

The cathodic reaction mechanism of a solid oxide fuel cell (SOFC) was investigated for an electrode-electrolyte system of Lao(0.6)Ba(0.4)CoO(3) (LBC)-BaCeO(3), under both the O(2-) conducting and H(+)/O(2-) mixed-ionic conducting conditions. AC impedance measurements were carried out, and the electrode interfacial conductivities were calculated. The experimental results revealed that the processes dominating the electrode resistance for the O(2-) conducting and the H(+)/O(2-) mixed-ionic conducting conditions are different. It was also found that the process dominating the electrode resistance changes at 700 degrees C under H(+)/O(2-) mixed-ionic conducting conditions. The process dominating the electrode resistance above 700 degrees C is Postulated to be the reaction O(LBC) + H(LBC) --> OH(LBC). LBC showed high-performance cathode characteristics for a SOFC using BaCeO(3) electrolyte. (C) 2000 The Electrochemical Society. S0013-4651(99)05-072-7. All rights reserved.