The Research Of The Process Parameters For Electrolyte Films Prepared By Screen-Printing

Solid oxide fuel cell (SOFC) is attracting widely attentions by many countries because of its high-energy conversion efficiency, low pollution, high powder density and modularity. For the commercialization of SOFC, the low cost fabrication technology of thin electrolyte film became a key step. Screen-printing technology has been used in the fabrication of thin electrolyte film. Because the thickness and the density of the electrolyte are exerting a direct effect on the properties of the cell, solid electrolyte is the most important part of SOFC.In this paper, the technological parameters including printing times of the SDC film, the composition of the SDC screen-printing ink, sintering temperature of the screen-printed SDC green film and the component of NiO-SDC anode, were investigated. The results show that the SDC printing times has asignificant influence on the microstructure and properties of SDC electrolyte. When the printing times of the SDC film is belowe five, the open-circuit voltage (OCV) of the single cell is very low. At least five-layers of printing is essential to get a SDC electrolyte film with high performance. Both the microstructure and the properties of SDC electrolyte film are related to the composition of the SDC screen-printing ink. There are many pin holes and cracks on the face of the sintered SDC film, when the weight percentage of SDC power is high or low. Only when the percentage is near 40%, the sintered SDC film has neither pin hole nor crack, and the single cell performed well. The sintering temperature of the screen-printed SDC green film is important as well. If the sintering temperature is low, the sintered SDC film has poor density, and the OCV of the single cell is below 0.7V. 1400℃is the lowest temperature to get a dense SDC electrolyte film. The ratio of NiO to SDC also plays an important role on the properties of single cell. After reduction, the conductivity of the anode which is mixed with the NiO and SDC in a ratio of 65:35 is 1820S/cm. The performance of the single cell with this anode is excellent at intermediate temperature, and the maximum power density is as high as 1.07W/cm² at 650℃.The anode-supported SOFC with Al₂O₃-doped Zr_0.84Y_0.16O_1.92 (YSZ) electrolyte by screen-printing technology is also investigated. The results show that the performance of the cell with 4 wt.% Al₂O₃-doped YSZ electrolyte film is never improved. The dope of Al₂O₃ has a bad effect on the OCV, power density and impedance of the single cell.