Abstract
Iron doped layered structured perovskites, PrBaCo 2− x Fe x O 5+ δ ( 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 CO 2, compatibility with electrolytes, thermal expansion coefficient, electrical conductivity, and cathodic interfacial polarization resistance. The lattice parameter and oxygen nonstoichiometry content, δ, at room temperature increase, whereas the conductivity, thermal expansion coefficient, and cathodic performance decrease with increasing iron content, x. PrBaCo 2− x Fe x O 5+ δ exhibit excellent stability at 700 °C in atmosphere consisting of 3% CO 2 and 97% air, show good chemical compatibility with doped ceria electrolytes at 1000 °C, but react readily with yttria-stabilized zirconia at 700 °C. Even with a Co-free PrBaFe 2O 5+ δ as the electrode, a symmetrical cell demonstrates area specific resistance of 0.18 Ω cm 2 at 700 °C with samaria-doped ceria electrolyte. The resistance is lower than those for typical Co-free electrodes reported in the literatures, suggesting that PrBaCo 2− x Fe x O 5+ δ are potential promising cathode materials for IT-SOFCs.
Published Version
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