Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)-Sm_(0.5)Sr_(0.5)CoO_(3-δ)复合阴极材料的性能研究

Study on Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)-Sm_(0.5)Sr_(0.5)CoO_(3-δ) Composite Cathode Materials

为发展中温固体氧化物燃料电池(IT-SOFC)的阴极材料,用柠檬酸络合法合成了Ba0.5Sr0.5Co0.8Fe0.2O3-δ(BSCF)粉体,并在BSCF中加入一定量的Sm0.5Sr0.5CoO3-δ(SSC)粉体作为SOFC的阴极材料。X-ray衍射方法研究了复合阴极Ba0.5Sr0.5Co0.8Fe0.2O3-δ-xSm0.5Sr0.5CoO3-δ(BSCF-xSSC,x=0%～40%质量分数)系列样品的成相情况,结果表明Ba0.5Sr0.5Co0.8Fe0.2O3-δ(BSCF)和Sm0.5Sr0.5CoO3-δ(SSC)二者在烧结过程中发生了明显反应,生成了比较复杂的固溶物。高温电阻测试表明复合阴极材料(BSCF-xSSC)比纯BSCF材料具有较高的电导率,在600℃,BSCF-30SSC复合阴极的电导率可达143S cm-1,大约是纯BSCF材料的5倍。同时用交流阻抗法研究了BSCF-xSSC复合阴极材料的性能,实验结果表明SSC的掺杂量为30%时,阴极极化电阻最小,在600℃极化电阻值仅为0.24Ωcm2,大约为纯BSCF阴极材料的1/11。这标志着掺杂SSC的BSCF作为中低温固体氧化物燃料电池的阴极材料是非常具有发展前景的。

In order to develop a cathode for IT-SOFC, Ba0.5Sr0.5Co0.8Fe0.2O3-δ（BSCF）,powders were prepared by an EDTA-Pechini method, and with some Sm0.5Sr0.5CoO3-δ（SSC） as the cathode materials of SOFC. Ba0.5Sr0.5Co0.8Fe0.2O3-δ（BSCF-xSSC, x=0%-40wt% ） 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 143S cm^-l at 600 ℃ for the x=30wt% composite, which was nearly 5 times 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 30wt%, e.g., the polarization resistance value of BSCF-30wt%SSC was only 0.24 Ω cm^2 at 600 ℃ , about one-eleventh of that BSCF at 600 ℃.