High-conductivity electrolyte with a low sintering temperature for solid oxide fuel cells

Bismuth oxide and scandia co-doped zirconia (Sc₂O₃)_0.06(Bi₂O₃)_x(ZrO₂)_0.94–x (ScSZB, x = 0, 0.01, 0.03, 0.05, 0.07, 0.1) powders are prepared via a citrate sol-gel method. Bi₂O₃ promotes the sintering process of scandia stabilized zirconia (ScSZ) and increases electrical conductivity of system. A high conductivity of ～0.094 S/cm at 800 °C is achieved on 5 mol% Bi₂O₃ doped ScSZ (ScSZB05). X-ray Rietveld refinement and transmission electron microscope (TEM) analysis of the ScSZB05 reveal the formation of cubic phase and rhombohedral phase at room temperature. The electrolyte-supported cell constructed by the ScSZ electrolyte gives the maximum power density of 258.3 mW/cm² at 800 °C, while the cell with ScSZB05 electrolyte shows a higher value of 387.6 mW/cm². The performance obtained by theoretical simulation of the two electrolyte-supported cells is in good agreement with the experimental results.