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 inves tigated for an electrode-electrolyte system of Lao(0.6)Ba(0.4)CoO(3) (LBC)- BaCeO3, under both the O2- conducting and H+/O2- mixed-ionic conducting con ditions. AC impedance measurements were carried out, and the electrode inte rfacial conductivities were calculated. The experimental results revealed t hat the processes dominating the electrode resistance for the O2- conductin g and the H+/O2- mixed-ionic conducting conditions are different. It was al so found that the process dominating the electrode resistance changes at 70 0 degrees C under H+/O2- mixed-ionic conducting conditions. The process dom inating the electrode resistance above 700 degrees C is Postulated to be th e reaction O-LBC + H-LBC --> OHLBC. LBC showed high-performance cathode cha racteristics for a SOFC using BaCeO3 electrolyte. (C) 2000 The Electrochemi cal Society. S0013-4651(99)05-072-7. All rights reserved.