中温SOFC复合阴极材料BSCN0.6-30%GDC的表征

通过固相反应法制备了钙钛矿氧化物Ba0.6Sr0.4Co0.9Nb0.1O3-δ(简称BSCN0.6),采用XRD对BSCN0.6与Gd0.1Ce0.9O1.95(简称GDC)电解质间的高温化学相容性进行表征。结果表明,BSCN0.6与GDC高温煅烧后存在微弱的固溶反应,但并未对阴极性能造成不利影响。将BSCN0.6与质量分数为30%的GDC复合(简称BSCN0.6-30%GDC)后作SOFC阴极,采用四电极法测电导、热膨胀测试等手段对复合阴极进行表征。结果表明,BSCN0.6与GDC复合降低了材料的电导率,同时也降低了材料的热膨胀系数,提高了阴极与GDC电解质间的热匹配性。以BSCN0.6-30%GDC复合材料作电极,700~800℃时对称电池BSCN0.6-30%GDC//GDC的极化阻抗为0.047~0.012Ω·cm2。因此,BSCN0.6-30%GDC复合材料有望作IT-SOFC的低极化阻抗的阴极材料。

Investigation of BSCN0.6-30%GDC Composite Cathode for IT-SOFC

Ba0.6Sr0.4 Co0.9 Nb0.1 O3-δ(BSCN)perovskite-type oxide was prepared by the solid state reaction.The high temperature chemical compatibility between BSCN0.6and Gd0.1Ce0.9O1.95(GDC)were analyzed by XRD.XRD patterns indicate that a week solid solution between BSCN0.6and GDC takes place after the BSCN0.6-GDC composite material was calcined at high temperature.However,this solid solution does not show a negative effect on the performance of the cathode.The mixture of BSCN0.6and GDC in a weight ratio of 70∶30was used as SOFC composite cathode and the electrical property,thermal expansion behavior and electrochemical performance were investigated.The electrical conductivity was found to decrease with increasing GDC content;however,the thermal expansion coefficients(TEC)of BSCN0.6-30% GDC composite cathode decreased,which enhances the thermal match between the cathode and GDC electrolyte.With BSCN0.6-30%GDC as the electrode,the polarization resistance of a symmetrical cell BSCN0.6-30%GDC//GDC is only 0.047~0.012Ω·cm2 in 700~ 800℃.Therefore,BSCN0.6-30%GDC composite material is a promising IT-SOFC cathode.