A layered Perovskite EuBaCo2O5+d for intermediate-temperature solid oxide fuel cell cathode
Résumé
A layered perovskite EuBaCo2O5+δ (EBCO) has been prepared by a solid-state reaction, and evaluated as potential cathode for intermediate-temperature solid oxide fuel cells. Structural characterizations are determined at room temperature using powder X-ray diffraction and transmission electron microscopy technique. The good fits to the XRD data by Rietveld refinement method are obtained in the orthorhombic space group (Pmmm). The lower average thermal expansion coefficient, 14.9 × 10–6 °C–1 between 100 and 800 °C, indicates its better thermal expansion compatibility with conventional electrolytes, compared with the other cobalt-containing cathode materials. The high electrical conductivity and large oxygen nonstoichiometry at intermediate temperatures suggest the effective charge transfer reactions including electron conduction and oxide-ion motion in cathode. As a result, a highly electrochemical activity towards the oxygen reduction reaction is achieved between 600 and 700 °C, as evidenced by low area-specific resistances, e.g. 0.14–0.5 Ω cm2. In addition, cathodic overpotential and oxygen reduction kinetics of the EBCO cathode have also been studied.