Formulation of the anode of an integrated-reforming solid-oxide fuel cell

Nickel cermets are used to solve three problems found in the technology of solid-oxide fuel cells: thermal compatibility between anode and electrolyte, high electronic conduction for production of electrical energy and catalytic activity for transformation of fuels; thermal compatibility and, most important, electronic conductivity are strong functions of the nickel content in the cermet. The formulation of nickel cermets is presently an open problem and the work subject of this dissertation is a contribution to this field of technology.;In this work a screening process of methods of synthesis to discriminate among several formulations of an anode for a solid-oxide fuel cell (SOFC) is presented. The typical components of a SOFC are yttria-stabilized zirconia (YSZ) as the electrolyte, lanthanum-strontium manganate as cathode, nickel is used in the anode and lanthanum chromites are used as interconnects between fuel cell units in a fuel cell stack. The ionic conductivity of the electrolyte as well as the catalytic activity of the anode require the operation of a SOFC to be carried out at high temperatures (above 1000;The use of a nickel cermet as anode of a solid-oxide fuel cell attempts to address the thermal incompatibility among the cell components; a nickel cermet is a composite of nickel metal and yttria-stabilized zirconia.;In this research several methods of synthesis were used to formulate Ni-YSZ composites. All materials were fully characterized from the point of view of structure by X-ray diffraction of powders, total nickel content and nickel oxide reducibility were determined by the techniques of magnetometry and temperature-programmed reduction. Samples prepared by a coprecipitation method and by the incipient wetness method showed the higher values of nickel content and were chosen to carry out measurements of their electrical conductivity. A sample prepared by the incipient wetness method had the highest values of electrical conductivity and was chosen to measure its catalytic activity in steam-reforming and CO...