Preparação e caracterização de anodo Ni/YSZ com aplicação em pilhas a combustível de óxido sólido

Abstract

Solid Oxide Fuel Cells (SOFC) are devices that convert energy generated by electrochemical reaction into electrical energy and get highlighted because of their minimal emission of toxic pollutants and high efficiency. They consist of anode, electrolyte, cathode, interconnects and sealant. The porous anode Ni/YSZ is the most common material used for applications in SOFCs due to its low cost, chemical stability in reducing environment at high temperatures and it is a good electronic and ionic conductor. Tape Casting is a technique for producing flat ceramic with wide area and has been widely used for the production of porous and thick support anode. Screen printing is a technique of easy operation and low cost commonly used for production of fine ceramics as electrolytes, anodes and cathodes. This study aimed to optimize the preparation of support anode Ni/YSZ by variation of parameters of Tape Casting technique and also get thin functional anode layers through screen printing technique. For optimization of the production of the support anode, fifteen different combinations were studied during the production of the tape, while six different suspensions were produced for the study of functional anode. The powders used in the study were characterized by X-ray diffraction, dynamic light scattering, thermal analysis and gaseous adsorption. The rheological behavior and thermal analysis of the suspensions were evaluated. The microstructures of anodes produced were obtained by Scanning Electron Microscopy. From the best support anode and functional anode suspension, six different cells were produced to conduct the electrochemical measurements. The measures of impedance and density of power of the half-cells had shown the influence of the porosity, presence of functional anode, CGO electrolyte presence on the resistances and electrochemical performance of the same ones. The highest power density obtained among the cells was 1080 mWcm-2 at a temperature of 850 °C.