Hostname: page-component-8448b6f56d-mp689 Total loading time: 0 Render date: 2024-04-18T08:57:36.252Z Has data issue: false hasContentIssue false
  • English
  • Français

SURFACE SEGREGATION STUDIES OF SOFC CATHODES: COMBINING SOFT X-RAYS AND ELECTROCHEMICAL IMPEDENCE SPECTROSCOPY

Published online by Cambridge University Press:  31 January 2011

Lincoln Miara ,
Louis Piper ,
Jacob Nathan Davis ,
Laxmikant Saraf ,
Tiffany Kaspar ,
Soumendra Basu ,
Kevin E. Smith ,
Uday B. Pal  and
Srikanth Gopalan
Lincoln Miara
Affiliation:
lmiara@bu.edu, Boston University, Division of Materials Science, Brookline, Massachusetts, United States
Louis Piper
Affiliation:
lfjpiper@bu.edu, Boston University, Physics, Boston, Massachusetts, United States
Jacob Nathan Davis
Affiliation:
jndavis@bu.edu, Boston University, Division of Materials Science, Brookline, Massachusetts, United States
Laxmikant Saraf
Affiliation:
lax.saraf@pnl.gov, Pacific Northwest National Laboratory, Environmental and Molecular Laboratory, Richland, Washington, United States
Tiffany Kaspar
Affiliation:
tiffany.kaspar@pnl.gov, Pacific Northwest National Laboratory, Environmental and Molecular Laboratory, Richland, Washington, United States
Soumendra Basu
Affiliation:
basu@bu.edu, Boston University, Division of Materials Science and Engineering, 15 St. Mary's Street, Brookline, Massachusetts, 02446, United States
Kevin E. Smith
Affiliation:
ksmith@bu.edu, Boston University, Physics, Boston, Massachusetts, United States
Uday B. Pal
Affiliation:
upal@bu.edu, Boston University, Division of Materials Science, Brookline, Massachusetts, United States
Srikanth Gopalan
Affiliation:
sgopalan@bu.edu, Boston University, Division of Materials Science, Brookline, Massachusetts, United States
Get access

Abstract

A system to grow heteroepitaxial thin-films of solid oxide fuel cell (SOFC) cathodes on single crystal substrates was developed. The cathode composition investigated was 20% strontium-doped lanthanum manganite (LSM) grown by pulsed laser deposition (PLD) on single crystal (111) yttria-stabilized zirconia (YSZ) substrates. By combining electrochemical impedance spectroscopy (EIS) with x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy XAS measurements, we conclude that electrically driven cation migration away from the two-phase gas-cathode interface results in improved electrochemical performance. Our results provide support to the premise that the removal of surface passivating phases containing Sr2+ and Mn2+, which readily form at elevated temperatures even in O2 atmospheric pressures, is responsible for the improved cathodic performance upon application of a bias.

Keywords

x-ray photoelectron spectroscopy (XPS)thin filmelectronic structure
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1217: Symposium Y – Catalytic Materials for Energy, Green Processes and Nanotechnology , 2009 , 1217-Y07-04
Copyright
Copyright © Materials Research Society 2010

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

[1] I. EG&G Technical Services, “Fuel Cell Handbook (Seventh Edition),” p. 427, 2004.Google Scholar
[2] Baumann, F. S., Fleig, J., Konuma, M., Starke, U., Habermeier, H.-U., and Maier, J., “Strong Performance Improvement of La[sub 0.6]Sr[sub 0.4]Co[sub 0.8]Fe[sub 0.2]O[sub 3 - delta] SOFC Cathodes by Electrochemical Activation,” Journal of The Electrochemical Society, vol. 152, pp. A2074–A2079, 2005.Google Scholar
[3] Wang, W. and Jiang, S. P., “A mechanistic study on the activation process of (La, Sr)MnO3 electrodes of solid oxide fuel cells,” Solid State Ionics, vol. 177, pp. 1361–1369, 2006.Google Scholar
[4] Backhaus-Ricoult, M., Adib, K., Clair, T. St., Luerssen, B., Gregoratti, L., and Barinov, A., “In-situ study of operating SOFC LSM/YSZ cathodes under polarization by photoelectron microscopy,” Solid State Ionics, vol. 179, pp. 891–895, 2008.Google Scholar
[5] O, G. J. la, Savinell, R. F., and Shao-Horn, Y., “Activity Enhancement of Dense Strontium-Doped Lanthanum Manganite Thin Films under Cathodic Polarization: A Combined AES and XPS Study,” Journal of The Electrochemical Society, vol. 156, pp. B771–B781, 2009.Google Scholar
[6] Das, R., Mebane, D., Koep, E., and Liu, M., “Modeling of patterned mixed-conducting electrodes and the importance of sheet resistance at small feature sizes,” Solid State Ionics, vol. 178, pp. 249–252, 2007.Google Scholar
[7] Vance, A. A. and McIntosh, S., “Performance and Activation Behavior of Surface-Doped Thin-Film La[sub 0.8]Sr[sub 0.2]MnO[sub 3 - delta] Cathodes,” Journal of The Electrochemical Society, vol. 155, pp. B1–B7, 2008.Google Scholar
[8] Lee, H. Y., Cho, W. S., Oh, S. M., Wiemhofer, H. D., and Gopel, W., “Active Reaction Sites for Oxygen Reduction in La[sub 0.9]Sr[sub 0.1]MnO[sub 3]/YSZ Electrodes,” Journal of The Electrochemical Society, vol. 142, pp. 2659–2664, 1995.Google Scholar
[9] Barbucci, A., Bozzo, R., Cerisola, G., and Costamagna, P., “Characterisation of composite SOFC cathodes using electrochemical impedance spectroscopy. Analysis of Pt/YSZ and LSM/YSZ electrodes,” Electrochimica Acta, vol. 47, pp. 2183–2188, 2002.Google Scholar
[10] Baumann, F. S., Fleig, J., Habermeier, H.-U., and Maier, J., “Impedance spectroscopic study on well-defined (La,Sr)(Co,Fe)O3-[delta] model electrodes,” Solid State Ionics, vol. 177, pp. 1071–1081, 2006.Google Scholar
[11] Wang, W. and Jiang, S. P., “Effect of polarization on the electrode behavior and microstructure of (La,Sr)MnO 3 electrodes of solid oxide fuel cells,” Journal of Solid State Electrochemistry, vol. 8, pp. 914–922, 2004.Google Scholar
[12] Gilbert, B., Frazer, B. H., Belz, A., Conrad, P. G., Nealson, K. H., Haskel, D., Lang, J. C., Srajer, G., and Stasio, G. De, “Multiple Scattering Calculations of Bonding and X-ray Absorption Spectroscopy of Manganese Oxides,” The Journal of Physical Chemistry A, vol. 107, pp. 2839–2847, 2003.Google Scholar
[13] McLeod, R. G. W. J. A., Skorikov, N. A., Finkelstein, L. D., Abu-Samak, M., Kurmaev, E. Z., and Moewes, A., “Electronic structure of alkaline earth and post-transition metal oxides,” cond-mat.mtrl-sci arXiv:0908.1581v1, 2009.Google Scholar