Study on Ba-0.5 Sr0.5Co0.8Fe0.2O3-delta-Sm0.5Sr0.5CoO3-delta composite cathode materials for IT-SOFCs

作者：Wenwu Zhu, Zigui Lu, Shangbo Li, Bo Wei, J.P. Miao, Xiaolin Huang, Kuan-Ju Chen, N. Ai, Weiming Su · 年份：2008 · 研究领域：Advancements in Solid Oxide Fuel Cells、Electrocatalysts for Energy Conversion、Fuel Cells and Related Materials

Ba0.5Sr0.5Co0.8Fe0.2O3-delta-xSm(0.5)Sr(0.5)CoO(3-delta) (BSCF-xSSC, x=0-40wt%) composite cathodes supported on Sm0.2Ce0.8O1.9 (SDC) electrolyte were studied for applications in IT-SOFCs. X-ray diffraction patterns showed obvious solid-state reactions between BSCF and SSC. However, the composite materials exhibited higher conductivity than that of pure BSCF, e.g., around 176 S cm(-1) at 500 degrees C for the x= 30 wt% composite, which was nearly seven times higher than that of BSCF. The thermal expansion coefficients of the BSCF-SSC were between (18.0 and 21.9) x 10(-6) K-1 from 30 to 800 degrees C, which was slightly higher than that of BSCF. In addition, electrochemical impedance spectra exhibited the better performance of BSCF-SSC composite cathodes than pure BSCF. The results of the polarization resistance indicated that the optimum content of SSC in the composite cathodes was about 30 wt%, e.g., the polarization resistance value of BSCF-30 wt%SSC was only 0.71 Omega cm(2) at 550 degrees C, about one seventh of that BSCF at 550 degrees C. (C) 2007 Elsevier B.V. All rights reserved.