Effect of Cathode Porosity on the Cathodic Polarization Behavior of Mixed Conducting LSCF(La0.6Sr0.4Co0.2Fe0.8O3)

혼합전도체 LSCF(La0.6Sr0.4Co0.2Fe0.8O3) 양극의 기공률에 따른 양극분극 특성

  • Yun, Joong-Cheul (Department of Materials Science and Engineering, Korea University, Nano-Materials Research Center, KIST) ;
  • Lee, Jong-Ho (Nano-Materials Research Center, KIST) ;
  • Kim, Joosun (Nano-Materials Research Center, KIST) ;
  • Lee, Hae-Weon (Nano-Materials Research Center, KIST) ;
  • Kim, Byong-Ho (Department of Materials Science and Engineering, Korea University)
  • 윤중철 (고려대학교 재료공학과, 한국과학기술연구원 나노재료연구센터) ;
  • 이종호 (한국과학기술연구원 나노재료연구센터) ;
  • 김주선 (한국과학기술연구원 나노재료연구센터) ;
  • 이해원 (한국과학기술연구원 나노재료연구센터) ;
  • 김병호 (고려대학교 재료공학과)
  • Published : 2005.04.01


In order to characterize the influence of the reaction-site density on the cathodic polarization property of LSCF, we chose the porosity of LSCF as a main controlling variable, which is supposed to be closely related with active sites for the cathode reaction. To control the porosity of cathodes, we changed the mixing ratio of fine and coarse LSCF powders. The porosity and pore perimeter of cathodes were quantitatively analyzed by image analysis. The electrochemical half cell test for the cathodic polarization was performed via 3-probe AC-impedance spectroscopy. According to the investigation, the reduction of oxygen at LSCF cathode was mainly controlled by following two rate determining steps; i) surface diffusion and/or ionic conduction of ionized oxygen through bulk LSCF phase, ii) charge transfer of oxygen ion at cathode/electrolyte interface. Moreover, the overall cathode polarization was diminished as the cathode porosity increased due to the increase of the active reaction sites in cathode layer.


  1. N. Q. Minh, ' Ceramics Fuel Cell,' J. Am. Ceram. Soc., 76 [3] 563-88 (1993)
  2. A. B. Stambouli and Traversa, ' Solid Oxide Fuel Cells (SOFCs) : A Review of an Environmentally Clean and Efficient Source of Energy,' Renewable and Sustainable Energy Reviews, 6 433-55 (2002)
  3. B. C. H. Steele, ' Materials for IT-SOFC Stacks 35 years R&D : The Inevitability of Gradualness?,' Solid State Ionics, 134 3-20 (2000)
  4. B. C. H. Steele, ' Ceramic Ion Conducting Membranes,' Current Opinion in Solid State & Mater. Sci., 1 684-91 (1996)
  5. A. Esquirol, N. P. Brandon, J. A. Kilner, and M. Mogensen, ' Electrochemical Characterization of $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3}$ Cathodes for Intermediate-Temperature SOFCs,' J. Electrochemical Soc., 151 [11] A1847-A55 (2004)
  6. S. Diethelm and J. V. Herle, ' Oxygen Transport Through Dense $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3}$ Perovskite-Type Permeation Membranes,' J. European Ceram. Soc., 24 1319-23 (2004)
  7. F. H. van Heuveln, F. P. F. van Berkel, and J. P. P. Huijsmans, ' Characterization of Solid Oxide Fuel Cell Electrodes by Impedance Spectroscopy and I-V Characteristics,' Solid State Ionics, 72, 240-47 (1994)
  8. F. H. van Heuveln and H. J. M. Bouwmeester, ' Electrode Properties of Sr-Doped $LaMnO_{3}$ on Yttria-Stabilized Zirconia,' J. Electrochem. Soc., 144 133-40 (1997)
  9. H. Y. Lee, W. S. Cho, S. M. Oh, H. D. Wiemhofer, and W. Gopel, ' Active Reaction Sites for Oxygen Reduction in $La_{0.9}Sr_{0.1}MnO_{3}$/YSZ Electrodes,' J. Electrochem. Soc., 142 [8] (1995)
  10. J. D. Kim, G. D. Kim, J. W. Moon, Y. I. Park, W. H. Lee, K. Kobayashi, M. Nagai, and C. E. Kim, ' Characterization of LSM-YSZ Composite Electrode by AC Impedance Spectroscopy,' Solid State Ionics, 143 379-89 (2001)
  11. M. Liu and J. Winnick, ' Fundamental Issues in Modeling of Mixed Ionic-Electronic Conductors (MlECs),' Solid State Ionics, 118 11-21 (1999)
  12. J. Fleig, ' On the Width of the Electrochemically Active Region in Mixed Conducting Solid Oxide Fuel Cell Cath-odes,' J. Power Sources, 105 228-38 (2002)
  13. J. C. Russ, The Image Processing Handbook, 2nd Edition, pp. 481-546, CRC Press, Boca Raton, 1995
  14. G. Hsieh, G. J. Ford, T. O. Mason, and L. R. Pederson, ' Experimental Limitations in Impedance Spectroscopy: Part I-Simulation of Reference Electrode Artifacts in Three-Point Measurements,' Solid State Ionics, 91 191-201 (1996)
  15. G. Hsieh, G. J. Ford, T. O. Mason, and L. R. Pederson, ' Experimental Limitations in Impedance Spectroscopy: Part 2-Electrode Artifacts in Three-Point Measurements on Pt/YSZ,' Solid State Ionics, 91 203-12 (1996)
  16. G. Hsieh, T. O. Mason, E. J. Garboczi, and L. R. Pederson, 'Experimental Limitations in Impedance Spectroscopy : Part 3-Effect of Reference Electrode Geometry/Position,' Solid State Ionics, 96 153-72 (1997)
  17. J. R. Macdonald, ' Impedance Spectroscopy: Emphasizin Solid Materials and Systems,' pp. 1-26, 84-132, John Wiley &Sons, New York, 1987
  18. J. E. Bauerle, ' Study of Solid Electrolyte Polarization by a Complex Admittance Method,' J. Phys. Chem. Solids, 30 2657-70 (1969)
  19. S. P. Jiang, J. G. Love, J. P. Zhang, M. Hoang, Y. Ramprakash, A. E. Hughes, and S. P. S. Bandwal, ' The Electrochemical Performance of LSM/Zirconia-Yttria Interface as a Function of A-Site Non-Stoichiometry and Cathodic Current Treatment,' Solid State Ionics, 121 1-10 (1999)