La0.4Ce0.6O1.8-La0.8Sr0.2MnO3-8 mol% yttria-stabilized zirconia composite cathode for anode-supported solid oxide fuel cells

The composite cathodes of La0.4Ce0.6O1.8 (LDC)-La0.8Sr0.2MnO3 (LSM)-8 mol% yttria-stabilized zirconia (YSZ) with different LDC contents were investigated for anode-supported solid oxide fuel cells with thin film YSZ electrolyte. The oxygen temperature-programmed desorption profiles of the LDC-LSM-YSZ composites indicate that the addition of LDC increases surface oxygen vacancies. The cell performance was improved largely after the addition of LDC, and the best cell performance was achieved on the cells with the composite cathodes containing 10 wt% or 15 wt% LDC. The electrode polarization resistance was reduced significantly after the addition of LDC. At 800 degrees C and 650 degrees C, the polarization resistances of the cell with a 10 wt% LDC composite cathode are 70% and 40% of those of the cell with a LSM-YSZ composite cathode, respectively. The impedance spectra show that the processes associated with the dissociative adsorption of oxygen and diffusion of oxygen intermediates and/or oxygen ions on LSM surface and transfer of oxygen species at triple phase boundaries are accelerated after the addition of LDC. (C) 2007 Elsevier B.V. All rights reserved.