Study On Preparation And Performance Of Direct Oxide Anode For Intermediate-Temperature SOFC

Nowadays, SOFC with the anode using methane or other hydrocarbon as the fuel has been the focus of global study. Coking and relatively low power density are now the primary obstacle for the further development of SOFCs using methane gas as the fuel. Therefore, this work studied these two problems.In this work the porous Ni-YSZ anode/electrolyte matrix and porous YSZ anode/electrolyte matrix were prepared by tape casting. CeO₂-Ni-YSZ anode, Cu-CeO₂-YSZ anode, Cu-Ni-YSZ anode and CeO₂-Cu-Ni-YSZ anode were fabricated by impregnating Cu and CeO₂ into the anode. Reaearch results indicated that anode porosity, impregnation pressure and impregnation order showed great impacts on the performance of the electrode.The discharge performance and electrochemical impedance spectroscopy measurements exhibited that best cell performance was obtained using Ni-YSZ anode with function layer containing 1g starch. The addition of CeO₂ would not only improve the performance of the anode, but also reduce the carbon deposition on the anode when methane was used. At 800°C, the power density of cell with LSM50 as cathode, CeO₂-Ni-YSZ with 2mass% CeO₂ as anode reached 378 mW/cm2 in hydrogen and 238 mW/cm2 in methane, respectively. The mass of Ni-CeO₂-YSZ anode increased by 5.4% after 30min in dry CH4, and this indicated that the performance of CeO₂-Ni-YSZ anode was not stable enough under the methane conditions.In order to avoid carbon deposition on the anode when using methane as fuel, the stability of Cu-CeO₂-YSZ anode was studied. The power density of cell with 10mass%CeO₂-20mass%Cu-YSZ anode were 113mW/cm2 and 20mW/cm2 at 800℃in H2 and CH4, respectively. Cu-CeO₂-YSZ anode showed low catalytic activity in CH4. To improve the performance of cell we added Ni which has better catalytic properties with CH4 was added into the anode, CeO₂-Cu-Ni-YSZ anode demonstrated better stability in methane, and the power densities of the cell using such anode reeched 302 mW/cm2 in H2 and 80mW/cm2 in CH4.