International Journal of Hydrogen Energy, Vol.36, No.5, 3658-3665, 2011
Synthesis, characterization and evaluation of PrBaCo2-xFexO5+delta as cathodes for intermediate-temperature solid oxide fuel cells
Iron doped layered structured perovskites, PrBaCo2-xFexO5+delta (x = 0, 0.5, 1.0, 1.5 and 2.0), are evaluated as cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The effects of dopant content are investigated on their structural and electrochemical properties including crystalline structure, oxygen nonstoichiometry, stability in presence of CO2, compatibility with electrolytes, thermal expansion coefficient, electrical conductivity, and cathodic interfacial polarization resistance. The lattice parameter and oxygen nonstoichiometry content, delta, at room temperature increase, whereas the conductivity, thermal expansion coefficient, and cathodic performance decrease with increasing iron content, x. PrBaCo2-xFexO5+delta exhibit excellent stability at 700 degrees C in atmosphere consisting of 3% CO2 and 97% air, show good chemical compatibility with doped ceria electrolytes at 1000 degrees C, but react readily with yttria-stabilized zirconia at 700 degrees C. Even with a Co-free PrBaFe2O5+delta as the electrode, a symmetrical cell demonstrates area specific resistance of 0.18 Omega cm(2) at 700 degrees C with samaria-doped ceria electrolyte. The resistance is lower than those for typical Co-free electrodes reported in the literatures, suggesting that PrBaCo2-xFexO5+delta are potential promising cathode materials for IT-SOFCs. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.