Electrochemical estimation of GBCO(GdBaCo2O5+δ)/GDC(Gd2O3-doped CeO2) cathode composites designed for intermediate-temperature solid oxide electrochemical cells

Double (or layered) perovskite GdBaCo2O5+δ (GBCO) was synthesized via a glycin nitrate process. This mixed ionic-electronic GBCO was composited to ionic GDC conductors as a cathode system for intermediate-temperature solid oxide fuel cells. The electrochemical features of these GBCO/GDC cathodes were investigated via frequency-dependent impedance spectroscopy with a geometric restriction at the cathode/electrolyte interface. Compared to the pure GBCO system, the GBCO/GDC composites exhibited a gradual increase in their electrochemical polarization. The optimized composition was determined to be 75 wt%:25 wt% GBCO:GDC. The larger GBCO fraction is believed to exhibit high mixed ionic-electronic conduction due to the oxygen vacancies in its crystal structure, found in the [Gd–O] layers.