LOW TEMPERATURE REDUCTION KINETICS OF SOLID OXIDE FUEL CELL (SOFC) ANODES

摘要

The reduction kinetics of SOFC composite anodes comprised of NiO-YSZ was investigated at temperatures below 800°C. Dense samples of NiO + YSZ were fabricated by conventional ceramic processes and reduced in a flowing hydrogen atmosphere in the temperature range 600 to 800°C. The effects of temperature and microstructure on the rate of reduction were studied. In the temperature range 600-800°C and for anodes with a thickness up to 1 mm, the reduced layer thickness exhibited linear dependence on reduction time indicating that the kinetics was interface-controlled and not diffusion-controlled. The reduction kinetics was dependent on temperature with reduction rates increasing by an order of magnitude over the temperature range 600-800°C. However, differences in the microstructures of the as-sintered anodes did not significantly affect reduction rates. A phenomenological model of the reduction process was developed which accounts for gas diffusion and interfacial reactions.