The effect of alumina and Cu addition on the electrical properties and the SOFC performance of Gd-doped CeO2 electrolyte

Alumina and transition metals were added to Gd-doped ceria and the electrical properties of doped ceria were studied. For 10 mol% Gd-doped ceria (GDC), 1 at.% transition metals (Fe, Co, Ni, Cu, or Ga) were added as a sintering aid and 1, 2, 5, 10, and 20 at.% alumina was added as a possible strengthening media. The electrical conductivity was measured as a function of temperature (250–700 °C) in air. The open circuit voltage (OCV) and the impedance spectra of the cell in dual atmosphere (air on one side, hydrogen on another side) were measured as a function of time. Samples added with both 1 at.% Cu and 2 at.% alumina showed good sinterability without much loss of electrical conductivity. The time-dependence of the OCV value and the impedance spectra showed that either the alumina-added or the Cu and alumina co-added sample exhibited the slower degradation of OCV and the less electrode polarization than GDC. The results indicate that Cu and alumina addition improved the stability of the cell.