Addition effects of erbia-stabilized bismuth oxide on ceria-based carbonate composite electrolytes for intermediate temperature--solid oxide fuel cells

Title
Addition effects of erbia-stabilized bismuth oxide on ceria-based carbonate composite electrolytes for intermediate temperature--solid oxide fuel cells
Authors
백승석이내성김병국장혜정송선주박준영
Keywords
SOFC; Intermediate temperature-solid oxide fuel cell; Doped ceria; Bismuth oxide; Carbonates; Composite electrolytes
Issue Date
2012-11
Publisher
International journal of hydrogen energy
Citation
VOL 37, NO 22, 16823-16834
Abstract
Highly conductive Er0.2Bi0.8O1.5 (ESB) and rare-earth doped ceria solid oxide electrolytes (SOEs) at intermediate temperature (IT) continue to suffer disadvantages in terms of thermodynamic instability and significant electronic conduction, respectively, at low oxygen partial pressure for solid oxide fuel cell (SOFC) operations. It is therefore necessary to improve the low-temperature ionic conductivity in order to enhance the electrolytic domain of these materials and thereby mitigate cell efficiency dissipation by electronic conduction. In this work, an advanced multiphase carbonate composite material based on ceria has been developed to overcome this IT-SOE challenge. This advanced electrolyte is comprise of nanostructured neodymium-doped ceria (NDC) and 38 wt% (Lie0.5Na)2CO3 carbonate with a small amount of ESB phase. The addition of 2 wt% ESB in ceria-based materials decreases the grain boundary resistance of the SOEs in the IT range. Further, a small amount of highly conducting ESB phase in the NDC/[(Lie0.5Na)2CO3] composite electrolyte increases the overall conductivity of the composite SOEs. The NDC electrolyte containing 38 wt% carbonate shows the highest conductivity of 0.104 Scm-1 at 600 ℃, while the conductivity is increased to 0.165 Scm-1 by the addition of 2 wt% ESB. In addition, the activation energy of the multiphase composite electrolytes (0.52 eV) is lower than that of the NDC/carbonates (0.65 eV) in the IT range. This is attributed to the effect of the physical properties of the NDC sample, induced by the light ESB doping, on the ionic conductivity, and this effect is closely associated with the grain boundary property. Furthermore, the interfacial effects of the multiphase materials also contribute to the improved conductivity of this advanced composite electrolyte.
URI
http://pubs.kist.re.kr/handle/201004/44154
ISSN
03603199
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