High performance cathodes for solid oxide fuel cells prepared by infiltration of La0.6Sr0.4CoO3-δ into Gd-doped ceria

Cathodes prepared by infiltration of La0.6Sr0.4CoO3-delta (LSC40) into a porous Ce0.9Gd0.1O1.95 (CGO10) backbone have been developed for low temperature solid oxide fuel cells. The CGO10 backbone has been prepared by screen printing a CGO10 ink on both sides of a 180 mu m dense CGO10 electrolyte-tape followed by firing. LSC40 was introduced into the CGO10 porous backbone by multiple infiltrations of aqueous nitrate solutions followed by firing at 350 degrees C. A systematic study of the performance of the cathodes was performed by varying the CGO10 backbone firing temperature, the LSC40 firing temperature and the number of infiltrations. The cathode polarization resistance was measured using electrochemical impedance spectroscopy on symmetrical cells in ambient air, while the resulting structures were characterized by scanning electron microscopy (SEM) and high temperature X-ray diffraction (HT-XRD). The firing temperature of 600 degrees C for the LSC40 infiltrate was found to provide a balance between LSC40 material formation and high surface area micro/nanostructure. The lowest polarization resistances measured at 600 and 400 degrees C were 0.044 and 2.3 Omega cm(2) in air, respectively. During degradation tests at 600 degrees C, the cathode polarization resistance levels out after about 450 h of testing, giving a final polarization resistance of 0.07 Omega cm(2). (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3571249] All rights reserved