中温固体氧化物燃料电池La1.6Sr0.4Ni1-xCuxO4阴极材料的制备及电化学性能

采用甘氨酸-硝酸盐法合成了中温固体氧化物燃料电池阴极材料La_1.6Sr_0.4Ni_1-xCu_xO₄ (x=0.2, 0.4, 0.6,0.8), 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. 结果表明, 该阴极材料与固体电解质Ce_0.9Gd_0.1O_1.95(CGO)在1000 °C烧结时不发生化学反应, 且烧结4 h 后, 二者之间可形成良好的接触界面. 利用电化学交流阻抗谱技术对阴极材料的电化学性能进行研究, 结果显示, 当Cu离子掺杂量(x)为0.6 时, La_1.6Sr_0.4Ni_0.4Cu_0.6O₄阴极具有最小的极化电阻, 在空气中当测试温度为750 °C时, 极化电阻为0.35 Ω·cm². 在不同氧分压条件下电化学阻抗谱分析结果表明, 电极上的两个氧还原反应主要包含氧离子从三相界面向电解质CGO 转移的过程和电荷的迁移过程, 其中电荷的迁移过程为电极反应的速率控制步骤.La_1.6Sr_0.4Ni_0.4Cu_0.6O₄电极在空气中700 °C和阴极电流密度为45 mA·cm^-2时, 阴极过电位为45 mV. 本研究的初步结果表明La_1.6Sr_0.4Ni_1-xCu_xO₄材料是一种电化学性能较为优良的新型中温固体氧化物燃料电池(IT-SOFC)阴极材料.

Synthesis and Electrochemical Properties of La1.6Sr0.4Ni1-xCuxO4 as Cathode Materials for Intermediate Temperature Solid Oxide Fuel Cells

Cathodic materials La_1.6Sr_0.4Ni_1-xCu_xO₄ (x=0.2, 0.4, 0.6, 0.8), for an intermediate temperature solid oxide fuel cell (IT-SOFC), were prepared by a glycine-nitrate process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). Results showed that no reaction occurred between the La_1.6Sr_0.4Ni_1-xCu_xO₄ electrode and the Ce_0.9Gd_0.1O_1.95 (CGO) electrolyte at 1000 °C, and that the electrode formed good contact with the electrolyte after sintering at 1000 °C for 4 h. Electrochemical AC impedance spectroscopy measurements were used to study cathodic performance. The La_1.6Sr_0.4Ni_0.4Cu_0.6O₄ cathode gave the lowest polarization resistance (R_p) of 0.35 Ω·cm² at 750 ° C in air. Electrode properties of La_1.6Sr_0.4Ni_1-xCu_xO₄ were studied under various temperatures and oxygen partial pressures. The two main oxygen reduction processes at the cathode are the oxygen ion transfer from the triple phase boundary to CGO electrolyte, and the charge transfer process. Charge transfer is the major rate limiting step for La_1.6Sr_0.4Ni_1-xCu_xO₄ cathode. The La_1.6Sr_0.4Ni_0.4Cu_0.6O₄ cathode exhibited the lowest overpotential, about 45 mV for a current density of 45 mA·cm^-2 at 700 °C in air. This preliminary work showed that the present La_1.6Sr_0.4Ni_1-xCu_xO₄ materials may be potential cathodes for use in IT-SOFCs.