Development of Nano-Composite Cu-based SOFC Anodes for Direct Utilization of Hydrocarbon Fuels

The anodes for direct utilization of hydrocarbon fuels have been developed by using Cu-based nano-composite powders. The CuO/GDC/YSZ-YSZ and CuO/GDC-GDC nano-composite powders were synthesized by coating nano-sized CuO, YSZ, and GDC particles selectively on the YSZ or GDC core particle by the Pechini process. The coated Cu particles after reducing CuO in the anode increase an electric conductivity as well as a carbon tolerance. On the other hand, the nano YSZ and GDC particles take a role for restraint of Cu coarsening and segregation during sintering and operation. Also, the GDC materials for having good catalysis about cracking reactions of hydrocarbon and electrochemical reactions of the oxidation of hydrogen are used because of no catalysis of Cu metal about same reactions. A single cell type with the Cu-based anode must be selected as an electrolyte-supported cell because an anode-supported cell can not be sintered together for the low melting temperature of Cu/CuO. The microstructure of the nano-composite powders showed high homogeneity and good necking structure of YSZ or GDC. The single cells by using the Cu-based nano-composite powders showed a long-term stability under high electronic load of 1 Acm^-2 until 200 hours in H₂ and CH₄ atmosphere. Also, The single cells showed a durability of thermal cycling for 10 cycles under same conditions. Among the single cells, the electrolyte-supported unit cell with Cu/GDC-GDC anode showed the maximum power density of 0.35 Wcm^-2 in H₂ and 0.3 Wcm^-2 in CH₄ atmosphere. The SOFC unit cell in conjunction with the CuO/GDC/YSZ-YSZ or CuO/GDC-GDC composite anodes showed the merits of suppressing the carbon formation and the good possibilities for direct utilization of hydrocarbon fuels.