Electrochemical characterization of multi-element-doped ceria as potential anodes for SOFCs

Abstract

Electrical conductivity of multi- element (Ca, Mn, Y)-doped ceria have been investigated using ac impedance measurement in the temperature range of 300–800 °C under air and H2. Fluorite-type metal oxides of the nominal chemical compositions Ce0.89Y0.1Mn0.01O2-δ (CYMO), and Ce0.87Y0.1Mn0.01M0.02O2-δ (M = Ca, Mg) were prepared via conventional ceramic (solid state) and combustion methods. The maximum total electrical conductivity of 0.2 S cm− 1 at 700 °C in H2 was observed for both Mg and or Ca-doped CYMO prepared via ceramic method at 1400 °C. The chemical compatibility of Mg-doped CYMO with 8 mol% yttria-stabilized zirconia (8YSZ) was investigated by powder X-ray diffraction (PXRD), which has shown reactivity between the mixed powders at above 1100 °C in air. Furthermore, scanning electron microscope (SEM) of cross-section area of CYMO/YSZ/CYMO cell configuration discerned formation of a diffusion dense zone at the interface with aggregates of different sizes embedded in the anode layer. The electrochemical performance of the anode has been studied in a symmetrical cell configuration in humidified H2 at 600–800 °C under open circuit condition. Area specific polarization (ASR) resistance of Mg-CYMO was found to be 0.225 Ω cm2 at 800 °C and is comparable to Ni–Cu–CeO2 and La0.65Ce0.1Sr0.25Cr0.5Mn0.5O3-δ (0.2 Ω cm2) under the comparable measurement conditions.