A novel composite cathode La0.6Sr0.4CoO3−δ–BaZr0.1Ce0.7Y0.1Yb0.1O3−δ for intermediate temperature solid oxide fuel cells

In this study, BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) was incorporated into La0.6Sr0.4CoO3−δ (LSC) to form a composite cathode LSC–BZCYYb. The X-ray diffraction (XRD) results demonstrate that BZCYYb has an extremely desirable chemical compatibility with LSC below 1200 °C. The thermal expansion coefficient (TEC) measurements indicate that incorporating 30 wt% BZCYYb enables the TEC of the composite cathode to be significantly reduced to 14.7×10−6 K−1 from 20×10−6 K−1 (LSC). The influence of the sintering temperature, composition and thickness on the microstructure as well as the electrochemical properties of the LSC–BZCYYb cathode were investigated. A Scanning electron microscope (SEM) testing shows that the LSC–BZCYYb cathode sintered at 950 °C has an optimum microstructure with good adhesion to the GDC interlayer and higher porosity. Electrochemical measurements reveal that 0.7LSC–0.3BZCYYb sintered at 950 °C with a thickness of approximately 20 μm possesses the minimum activation energy (Ea=1.32 eV) and polarization resistance (Rp), measuring approximately 0.116 Ω cm2 at 650 °C. This study confirms that the composite 0.7LSC–0.3BZCYYb cathode has the great potential to be a cathode material for intermediate temperature solid oxide fuel cells.