info:eu-repo/semantics/article
Study of the electrode polarization resistance of cobaltites with high Ba content as cathode for IT-SOFC
Fecha
2017-05Registro en:
Martinez, Cristian Fabricio; Prado, Fernando Daniel; Caneiro, Alberto; Study of the electrode polarization resistance of cobaltites with high Ba content as cathode for IT-SOFC; Electrochemical Society; Journal of the Electrochemical Society; 164; 7; 5-2017; F759-F767
0013-4651
CONICET Digital
CONICET
Autor
Martinez, Cristian Fabricio
Prado, Fernando Daniel
Caneiro, Alberto
Resumen
The phase relationships and the electrochemical behavior of cobaltites with high content of Ba, such as, La1-xBaxCoO3-δ with x = 0.5, 0.7 and 1.0, Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and BaCo0.7Fe0.2Nb0.1O3-δ (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 (Rp) values. The minimum Rp values were found to be 0.036 and 0.039 Ω cm2 at 600°C, in air, for La0.5Ba0.5CoO3-δ (LBC) and BSCF, respectively. The impedance spectra reveals mainly two processes, one at intermediate frequency (IF) in the range (0.1 ≤ f ≤ 5 × 103 Hz) and another at low frequency (LF) in the range (1 ≤ f ≤ 3 Hz). The variation of the parameter n (obtained from the log(RIF) vs. log(pO2) plots) in relation with the electrode configuration, indicates the rate-limiting process goes from a mixture of the ion transfer at the electrode/electrolyte interface and the charge transfer at the electrode surface to a mixture between this last process and the dissociation of the oxygen molecule.