Electrical Properties of BaCeO₃-Based Electrolytes for use in Dual Protonic Ceramic-Solid Oxide Fuel Cells

Abstract

Bulk samples consisting of BaCe0.85Y0.15O 3−δ (BCY15) and Ce0.85Y0.15O 2−δ (YDC15) compounds, mixed together in different ratios, were studied as potential electrolytes in dual protonic ceramic-solid oxide fuel cells and compared with non-composite BCY15 and YDC15. The microstructures of the sintered materials indicate that BCY15 exhibits the largest grains, whereas composites have greater visible porosity than the non-composite samples. From X-ray diffraction studies it follows that BCY15 and YDC15 consist mainly of one phase, whereas the composites are two-phase materials. Electrochemical impedance spectroscopy studies at different temperatures show that the composite materials are capable of conduction the order of 10 −3 S/cm at temperatures above 500• C in a hydrogen-containing atmosphere. Furthermore, activation energy values of the conductivity determined for the composites in air atmosphere are between those obtained for BCY15 (Ea = 0.590 ± 0.017 eV) and YDC15 (Ea = 1.132±0.008 eV). From this it follows that both phases of the composites influence the electrical conductivity of the materials. In conclusion, BCY15 and the BCY15-YDC15 composites show promise for future use as electrolytes in dual protonic ceramic-solid oxide fuel cells.