Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9781776 | Journal of Physics and Chemistry of Solids | 2005 | 6 Pages |
Abstract
Reaction between La0.6Sr0.4CoO3 electrode and yttria stabilized zirconia electrolyte (YSZ) was investigated at 973Â K to estimate its effect on performance of a solid oxide fuel cell at reduced operation temperatures. Since La0.6Sr0.4CoO3 is a good mixed conductor of electron and oxide ion, oxygen incorporation through the bulk diffusion is fairly fast if it is compared to the surface diffusion and reaction at triple phase boundaries (TPB). In order to simplify the oxygen reaction pathway, a dense electrode film of La0.6Sr0.4CoO3 was fabricated on an YSZ single crystal by pulsed laser deposition. Electrochemical measurements and secondary ion mass spectrometry (SIMS) analysis were performed before and after a long-term operation test for 3800Â h at 973Â K. Electrochemical impedance analysis enabled us to distinguish the contribution of the electrode/electrolyte interface resistance from the total electrochemical resistance. The interface resistance was almost independent of oxygen partial pressure, and increased with time according to the parabolic rate law. After the long-term test, Sr rich layer was found between the electrode and the electrolyte. The parabolic rate constant, kp, was obtained from the time dependence of the resistance and the thickness of the reaction layer. It was about 10â17 to 10â18Â cm2Â sâ1 at 973Â K, on the extrapolated line from the literature data measured at higher temperatures.
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Authors
M. Sase, D. Ueno, K. Yashiro, A. Kaimai, T. Kawada, J. Mizusaki,