Uso da técnica de serigrafia para deposição de filmes de catodo de pilha a combustível de óxido sólido

• Ano de defesa: 2012
• Autor(a) principal: Antonio de Padua Lima Fernandes
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Screen Print; PaCOS; Eletroquímica; LSCF; Serigrafia; SOFC; Físico-química; Células a combustível; Análise térmica
• Link de acesso: http://hdl.handle.net/1843/SFSA-8YBSDE

The cobaltite ferrite of strontium-doped lanthanum (LSCF) has beendemonstrated as a highly promising material for use as fuel cell cathodes of solid oxide due to its mixed conductivity (ionic and electronic) and high catalytic ability for the reduction reaction oxygen. The screen printing technique is a technique widely used for the production of cathode films. This low-cost technique is easy to operate and shows reproducible results. Considering these facts, this work aimed at obtaining different LSCF films from the variation of the parameters of screen printing equipment, thus seeking the combination ofparameters that allows to obtain films of cathode similar to those of commercial cells. The LSCF powder, with La0,6Sr0,4Co0,8Fe0,2O3- composition was synthesized by the citrate route. This powder was characterized by differential scanning calorimetry, adsorption and X-ray diffraction. A suspension was prepared from powder, which was characterized by differential scanning calorimetry and rheology. The suspension was used for the production of 45 cells, obtained by varying the rate deposition, the pressure of the squeegee and the screen mesh. The cell microstructures were analyzed by scanning electronmicroscopy and we selected the cells that most closely looked like with data obtained from literature. Cells using YSZ and CGO were produced as electrolyte. In all cases platinum anode was used. The conductivity and the power of the selected cells were studied by electrochemical impedance spectroscopy and linear voltammetry. The results indicated that the change in screen printing parameters directly influence the microstructure of the deposited cathodes. It was possibleto determine the best combination of parameters. The electrical measurements showed that the CGO electrolyte proves to be quite promising, showing better results for LSCF support cathode than the YSZ electrolyte. One of the cells produced using LSCF as cathode, CGO as electrolyte and platinum as anode gave the highest power obtained until now by our laboratory (Lampac)