关键词: 固体氧化物燃料电池(SOFC), 甲烷氧化, 阳极, 碳沉积, 交流阻抗

Abstract: A Ni-scandia-stabilized zirconia(Ni-ScSZ) cermet anode modified by coating with nano-sized gadolinium-doped ceria(GDC,Gd0.2Ce0.8O2) was prepared using a simple combustion process for the solid oxide fuel cell(SOFC) running on methane fuel.X-ray diffraction(XRD) and scanning electron microscopy(SEM) indicated that the surface of Ni-ScSZ was coated by nano-sized GDC particles(<100nm).Single cell testing showed that the 2.0%(by mass) GDC-coated Ni-ScSZ anode had better performance.The highest power densities of the cell with this anode were 825 and 848mW/cm2 at 850℃ in humidified hydrogen and methane,respectively,whereas the corresponding values were 584 and 586mW/cm2 for the cell with Ni-ScSZ anode.Electrochemical impedance spectra(EIS) illustrated that the cell with Ni-ScSZ anode exhibited far greater impedances than the cell with 2.0%(by mass) GDC-coated Ni-ScSZ anode.Then the short-term stability for the cells with the Ni-ScSZ and 2.0%(by mass) GDC-coated Ni-ScSZ anodes in 97%CH4/3%H2O at 700℃ was checked over a relative long period of operation.No significant degradation in performance has been observed after 84 h of cell testing when 2.0%(by mass) GDC-coated Ni-ScSZ anode was exposed to 97%CH4/3%H2O at 700 ℃.Very little carbon was detected on the anodes,suggesting that carbon deposition was limited during cell operation.

Key words: solid oxide fuel cell(SOFC), methane oxidation, anode, carbon deposition, electrochemical impedance spectroscopy