Effect of alumina additions on the anode|electrolyte interface in solid oxide fuel cells

Knibbe, R., Drennan, J., Dicks, A. L. and Love, J. (2008) Effect of alumina additions on the anode|electrolyte interface in solid oxide fuel cells. Journal of Power Sources, 179 2: 511-519. doi:10.1016/j.jpowsour.2007.12.111


Author Knibbe, R.
Drennan, J.
Dicks, A. L.
Love, J.
Title Effect of alumina additions on the anode|electrolyte interface in solid oxide fuel cells
Journal name Journal of Power Sources   Check publisher's open access policy
ISSN 0378-7753
1873-2755
Publication date 2008-05-01
Year available 2008
Sub-type Article (original research)
DOI 10.1016/j.jpowsour.2007.12.111
Open Access Status
Volume 179
Issue 2
Start page 511
End page 519
Total pages 9
Place of publication Lausanne, Switzerland
Publisher Elsevier Sequoia
Language eng
Subject C1
091205 Functional Materials
670901 Ceramics
0906 Electrical and Electronic Engineering
0912 Materials Engineering
Abstract The longevity of a solid oxide fuel cell (SOFC) stack is curtailed by the fragility of its ceramic components. At Ceramic Fuel Cells Limited (CFCL), 15 wt.% alumina is added to the commonly used 10 mol% Y2O3-ZrO2 (YSZ) electrolyte to improve both the fracture toughness and grain-boundary conductivity of the electrolyte. This study investigates the effect of such addition of alumina on the anode I electrolyte interface; more specifically, which reactions occur with the Al2O3 at the interface and how these reactions influence fuel cell performance. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize the formation of NiAl2O4 in the alumina regions in the electrolyte. The NiAl2O4 is observed to grow into the adjacent grain boundaries to form an interconnected NiAl2O4 network up to 4 mu m deep into the electrolyte. Impedance spectroscopy shows that the formation of NiAl2O4 does not affect the grain bulk ionic conductivity. The grain-boundary conductivity is markedly reduced at low temperatures. However, at the high SOFC operating temperature at CFCL (850 degrees C) the contribution of the grain-boundary conductivity to the total conductivity is diminished, and the NiAl2O4 is found not to have an effect on the total electrolyte conductivity and is deemed not to be a detrimental reaction. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.
Formatted abstract
The longevity of a solid oxide fuel cell (SOFC) stack is curtailed by the fragility of its ceramic components. At Ceramic Fuel Cells Limited (CFCL), 15 wt.% alumina is added to the commonly used 10 mol% Y2O3–ZrO2 (YSZ) electrolyte to improve both the fracture toughness and grain-boundary conductivity of the electrolyte. This study investigates the effect of such addition of alumina on the anode|electrolyte interface; more specifically, which reactions occur with the Al2O3 at the interface and how these reactions influence fuel cell performance. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize the formation of NiAl2O4 in the alumina regions in the electrolyte. The NiAl2O4 is observed to grow into the adjacent grain boundaries to form an interconnected NiAl2O4 network up to 4 μm deep into the electrolyte. Impedance spectroscopy shows that the formation of NiAl2O4 does not affect the grain bulk ionic conductivity. The grain-boundary conductivity is markedly reduced at low temperatures. However, at the high SOFC operating temperature at CFCL (850 °C) the contribution of the grain-boundary conductivity to the total conductivity is diminished, and the NiAl2O4 is found not to have an effect on the total electrolyte conductivity and is deemed not to be a detrimental reaction.
Crown copyright © 2008 Published by Elsevier B.V.

Keyword Solid oxide fuel cell
Nickel aluminate
Interface
Yttria-stabilized zirconia
Ionic conductivity;
Transmission electron microscopy
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2009 Higher Education Research Data Collection
Centre for Microscopy and Microanalysis Publications
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 8 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 11 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Wed, 15 Apr 2009, 01:21:34 EST by Jill Prescott on behalf of Faculty of Science