Solid State Ionics, Vol.262, 359-364, 2014
Electrochemical characterization of multi-element-doped ceria as potential anodes for SOFCs
Electrical conductivity of multi- element (Ca, Mn, Y)-doped ceria have been investigated using ac impedance measurement in the temperature range of 300-800 degrees C under air and H-2. Fluorite-type metal oxides of the nominal chemical compositions Ce0.89Y0.1Mn0.01O2-delta (CYMO), and Ce0.87Y0.1Mn0.01M0.02O2-delta (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 degrees C in H-2 was observed for both Mg and or Ca-doped CYMO prepared via ceramic method at 1400 degrees 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 degrees 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 H-2 at 600-800 degrees C under open circuit condition. Area specific polarization (ASR) resistance of Mg-CYMO was found to be 0.225 Omega cm(2) at 800 degrees C and is comparable to Ni-Cu-CeO2 and La0.65Ce0.1Sr0.25Cr0.5Mn0.5O3-delta (0.2 Omega cm(2)) under the comparable measurement conditions. (C) 2013 Elsevier B.V. All rights reserved.
Keywords:Multi-doped ceria;Chemical compatibility;Symmetrical cell;Electrochemical impedance spectroscopy;Area specific polarization;SOFC anodes