Improved phase stability and electrochemical performance of (Y,In,Ca)BaCo3ZnO7+δ cathodes for intermediate temperature solid oxide fuel cells

With an aim to combine the performance-enhancing properties of Ca with the stability-promoting properties of In in the swedenborgite YBaCo4O7+delta-based cathodes for solid oxide fuel cells (SOFC), cation-substituted Y1-x-yInxCayBaCo3ZnO7+delta (0.2 <= (x + y) <= 0.5) oxides have been explored. All samples presented in this work are stable in air after 120 h exposure to 600, 700, and 800 degrees C. Increasing In content shows a negligible impact on polarization resistances (R-p), but causes an increase in the activation energies (E-a) of (Y,In,Ca) BaCo3ZnO7+delta Gd0.2Ce0.8O1.9 (GDC) composite cathodes on 8 mol% yttria-stabilized zirconia (8YSZ) electrolyte supported symmetric cells. Increasing Ca content shows a decrease in R-p and an increase in E-a on similar electrochemical cells. All (Y,In,Ca)BaCo3ZnO7+delta samples investigated here show superior performance compared to the unsubstituted YBaCo3ZnO7+delta + GDC cathode in the range of 400-800 degrees C. Especially, the Y(0.5)in(0.1)Ca(0.4)BaCo(3)ZnO(7+delta) + GDC composite cathode exhibits good performance on GDC electrolytes in the range of 400-600 degrees C. With superior phase stability and electrochemical performance, the (Y,In,Ca)BaCo3ZnO7+delta series of oxides are attractive cathode candidates for intermediate temperature SOFCs. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.