Performance of Ln0.7Sr0.3Fe0.8Co0.2O3-d (Ln = Pr, La, Gd) Cathodes for Intermediate-Temperature SOFCs Synthesized by a Novel Gel-Combustion Route

I. RUIZ DE LARRAMENDI; D.G. LAMAS; A. FERNÁNDEZ; J.I. RUIZ DE LARRAMENDI; T. ROJO; N.E. WALSÖE DE RECA

ECS Transactions

The Electrochemical Society

Año: 2007 vol. 7 p. 1147 - 1155

1938-5862

Iron-cobalt-based perovskite materials with different A-site cations Ln0.7Sr0.3Fe0.8Co0.2O3-d  (Ln = La, Pr and Gd) were investigated for SOFC application as intermediate temperature cathodes. These samples were synthesized by a novel gel combustion process and characterized by X-ray diffraction. The diffraction patterns of the samples were indexed on the basis of an orthorhombic perovskite (GdFeO3-type) structure. The results of scanning electron microscopy showed that all of the powders have mean particle size less than 1 ..m. The polarization resistance of the cathodes with samaria-doped ceria as electrolyte was studied by Electrochemical Impedance Spectroscopy. The best performance was obtained for the praseodymium compound, which exhibit an ASR of 0.30 ohm.cm2 at 700°C, highly satisfactory value for technological applications, followed by the lanthanum one (0.42 ohm.cm2 at 700°C). The ASR values for the gadolinium compound were higher than the others (1.05 ohm·cm2 at 700°C).