Transport in ceria electrolytes modified with sintering aids: effects on oxygen reduction kinetics
authors Fagg, DP; Kharton, VV; Frade, JR
nationality International
journal JOURNAL OF SOLID STATE ELECTROCHEMISTRY
author keywords gadolinia-doped ceria; electrolyte; sintering aids; oxygen reduction kinetics; impedance spectroscopy
keywords OXIDE FUEL-CELLS; IONIC-CONDUCTIVITY; MICROSTRUCTURE; ELECTRODES; ELECTROCHEMISTRY
abstract Small (2 mol%) cobalt oxide additions to ceria-gadolinia (CGO) materials considerably improve sinterability, making it possible to obtain ceramics with 95-99% density and sub-micrometre grain sizes at 1,170-1,370 K. The addition of Co causes a significant shift of the electrolytic domain to lower pO(2). This modification to the minor electronic conductivity of the electrolyte material has influence on the cathodic oxygen reduction reaction. The impedance technique is shown to provide information not only about polarisation resistance, but also about the active electrode area from analysis of the current constriction resistance. It is demonstrated that this current constriction resistance can be related to the minor electronic contributions to total conductivity in these materials. A simple imbedded grid approach gives control of the contact area allowing the properties of the electrolyte materials to be studied. A much lower polarisation resistance for the Co-containing CGO electrolyte is observed, which can be clearly attributed to an increased three-phase reaction area in the Co-containing material, as a consequence of elevated p-type conductivity.
publisher SPRINGER
issn 1432-8488
year published 2004
volume 8
issue 9
beginning page 618
ending page 625
digital object identifier (doi) 10.1007/s10008-004-0509-x
web of science category Electrochemistry
subject category Electrochemistry
unique article identifier WOS:000223022400008
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journal impact factor 2.509
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