Effects of In substitution in Y1−xInxBaCo3ZnO7+δ (0 ≤ x ≤ 0.5) cathodes for intermediate temperature solid oxide fuel cells

Abstract

Y1−xInxBaCo3ZnO7+δ (0 ≤ x ≤ 0.5) oxides have been investigated as cathode materials for solid oxide fuel cells (SOFCs). While YBaCo3ZnO7+δ is observed to decompose after 120 h exposure to SOFC operating temperatures (600–700 °C), all the In-substituted compositions following Y0.9In0.1BaCo3ZnO7+δ are phase stable in the range of 600–800 °C. The substitution of In in the range of 0 < x ≤ 0.5 shows a negligible impact on the polarization resistances and activation energies of Y1−xInxBaCo3ZnO7+δ + Gd0.2Ce0.8O1.9 (GDC) composite cathodes on 8 mol% yttria-stabilized zirconia (8YSZ) electrolytes. The polarization resistances of YBaCo3ZnO7+δ (YBC3Z) + GDC cathodes decrease with decreasing electrolyte particle size, suggesting a strong dependence on the three-phase boundary region. Also, YBC3Z + GDC cathodes in symmetric cells on both 8YSZ and GDC electrolytes shows superior performance in the range of 400–600 °C compared to the well-studied Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) cathode. With a low thermal expansion coefficient, low intermediate temperature polarization resistances, and good phase stability, the Y0.9In0.1BaCo3ZnO7+δ oxide is an attractive cathode candidate for low and intermediate temperature SOFCs.