Study of the Electrode Polarization Resistance of Cobaltites with High Ba Content as Cathode for IT-SOFC

Abstract

The phase relationships and the electrochemical behavior of cobaltites with high content of Ba, such as, La1-xBaxCoO3-delta with x = 0.5, 0.7 and 1.0, Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) and BaCo0.7Fe0.2Nb0.1O3-delta (BCFN), were studied by XRD and impedance spectroscopy varying the electrode configurations from a single porous layer to a graded-cathode using Ce0.9Gd0.1O1.95 (GDC) as electrolyte. Regardless of the electrode material, symmetrical cells with graded-cathodes displayed the lowest polarization resistance (R-p) values. The minimum Rp values were found to be 0.036 and 0.039 Omega cm(2) at 600 degrees C, in air, for La0.5Ba0.5CoO3-delta (LBC) and BSCF, respectively. The impedance spectra reveals mainly two processes, one at intermediate frequency (IF) in the range (0.1