Journal
JOURNAL OF POWER SOURCES
Volume 195, Issue 4, Pages 1059-1064Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jpowsour.2009.08.074
Keywords
Ionic conductivity; Layered perovskite; Chemical diffusivity; Intermediate-temperature solid oxide fuel cell
Funding
- Ministry of Education, Science and Technology [R01-2007-000-20586-0]
- National Research Foundation of Korea [R01-2007-000-20586-0] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
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The transport properties of layered perovskite GdBaCo2O5+delta (GBCO), which has recently been proposed as a cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs), are investigated as a function of oxygen partial pressure (OPP) over the oxygen partial pressure range of 10(-4) <= pO(2) (atm) <= 0.21 at 1073 <= T(K) <= 1323. The increase in total conductivity with increasing temperature below the low-temperature, order-disorder transition indicates a semiconductor-type behaviour with an activation energy of 0.42 eV. When OPP is increased to air pressure at a fixed temperature, the total conductivity increases with an apparent slope (partial derivative log sigma/partial derivative log pO(2)) of 1/10 to 1/22. The maximum oxygen ion conductivity,as extracted from the oxygen permeation measurements,is around 0.01 S cm(-1) under the nitrogen condition, which strongly supports the potential for cathode application. The chemical diffusion coefficient((D) over tilde) and surface exchange coefficient (kappa) are also calculated from the d.c. conductivity relaxation measurement and the values are best fitted by the following two equations: (D) over tilde (cm(2) s(-1)) = 1.88 x 10(-2) exp (-0.77 eV/kT), kappa(cm s(-1)) = 1.37 x 10(0) exp (-0.86 eV/kT) (C) 2009 Elsevier B.V. All rights reserved.
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