中温固体氧化物燃料电池阴极材料Ba1-xSrxCo0.7Fe0.2Nb0.1O3-δ的制备与性能研究

Preparation and Performance of Cathode Materials Ba_(1-x)Sr_xCo_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) for Intermediate-temperature Solid Oxide Fuel Cells

采用固相法合成Ba1-x Srx Co0.7Fe0.2Nb0.1O3-δ(x=0、0.1、0.2、0.3、0.4)阴极材料。利用X射线衍射(XRD)和扫描电子显微镜(SEM)对其结构和微观形貌进行了表征。XRD测试结果表明Ba1-x Srx Co0.7Fe0.2Nb0.1O3-δ样品经1000℃,烧结10 h后形成了立方钙钛矿结构。从样品的电镜照片看出样品具有均匀的孔隙率,电解质(Ce0.85Sm0.15O1.925)-阴极(Ba1-x Srx Co0.7Fe0.2Nb0.1O3-δ)之间的界面结合良好。电化学交流阻抗测试结果表明Ba1-x Srx Co0.7Fe0.2Nb0.1O3-δ中掺入Sr可以明显地降低阴极的极化电阻,随着Sr含量的增多,阴极的界面极化电阻(RP)先减少后增大,当Sr的含量x为0.2时Rp值最小。以Ce0.85Sm0.15O1.925(SDC)电解质为支撑体,Ni0.9Cu0.1-SDC为阳极,Ba0.8Sr0.2Co0.7Fe0.2Nb0.1O3-δ为阴极的单电池的最大功率密度在600℃时达到155 mW/cm2。实验结果表明Ba0.8Sr0.2Co0.7Fe0.2Nb0.1O3-δ材料是一种电化学性能较为优良的中温固体氧化物燃料电池阴极材料。

The Ba1-xSrxCo0.7Fe0.2Nb0.1O3-δ（x=0, 0.1, 0.2, 0.3, 0.4） oxides were synthesized by the conventional solid state reaction process and investigated as a cathode for intermediate temperature solid oxide fuel cells （IT-SOFCs）. All prepared Ba1-xSrxCo0.7Fe0.2Nb0.1O3-δ（x=0-0.4） powders were sintered at 1000 ℃. X-ray diffraction patterns indicate that all samples have a single phase of cubic perovskite structure. The morphologies of the symmetric cell were characterized by a scanning electron microscope （SEM）. The cathode exhibits fine uniform microstructure with appropriate porosity, and shows good bonding and continuous contact with the dense Ce0.85Sm0.15O1.925（SDC） electrolyte pellet. AC impedance spectra based on SDC electrolyte measured at intermediate temperatures show that a cathode Ba0.8Sr0.2Co0.7Fe0.2Nb0.1O3-δ exhibits the best electrochemical performance. The maximum power density of single cell with Ba0.8Sr0.2Co0.7Fe0.2Nb0.1O3-δ cathode, Ni0.9Cu0.1-SDC anode and SDC electrolyte is 155 mW/cm2 at 600℃. The encouraging results suggest that Ba0.8Sr0.2Co0.7Fe0.2Nb0.1O3-δ is a very promising cathode material for IT-SOFCs.