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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

Abstract

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.

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