Research On Fabrication Process Of Intermediate Temperature Solid Oxide Fuel Cell

Solid oxide fuel cell (SOFC) is an energy conversion device that produces electricity (and heat) directly from fossil fuels by electrochemical reactions. Being several advantages, such as higher energy conversion efficiency, no noise and pollution, SOFC has been received considerable interests worldwide. In the present study, fabrication processes for a planar IT-SOFC single cell are principally explored. Detailed work is as following:Powders of gadolinium-doped cerium oxide Ce0.8Gd0.2O1.9(GDC), strontium-doped lanthanum manganese oxide La0.8Sr0.2MnO3(LSM), electrolyte and cathode material for Solid oxide fuel cell were prepared using solid reaction method. The particle size and its distribution were measured using granularity analysis instrument. The surface morphology and microstructure of powders were examined using a scanning electron microscope. Desirable phases were identified by X-ray diffraction. Tape casting and screen-printing processes, simple and cost-effective techniques, were used to fabricate the IT-SOFC single cell. Anode tape was prepared by tape casting. Electrolyte and cathode thin films were prepared by screen-printing. Several experiments were conducted to optimize the processing parameters of tape casting and screen-printing with polyvinyl alcohol slurries. The influence of the parameters on the quality of single cells was discussed.The anode/electrolyte co-firing and cathode sintering processes were explored. Factors resulting in defects, such as cracks, warping, pores in electrolyte, etc. were analyzed and discussed, and measures to avoid these defects were put forward. Co-firing results showed that the porosity of anode decreases with increasing sintering temperature. The porosity of anode is between 25% and 35% at temperature ranging from 1300℃ to 1400℃. Above 1400℃ the porosity of anode decreases rapidly, at 1450℃ the porosity of anode is only 15%, and inter-diffusion happens between the anode and the electrolyte, which will seriously affect the properties of the electrolyte. However, at 1400℃ the porosity of electrolyte is much higher than 5 %. Major reasons that result in the large porosity in the membrane are particle size of raw materials and sintering temperature. In order to prevent the inter-diffusion, decreasing particle size of the raw materials is the best way to improve the quality of the electrolyte film. The performance of a single cell Ni-GDC(1.5mm)/GDC(200μm)/LSM(200μm) was tested at 800℃. 0.83V open circuit voltage, 0.02W/cm 2 maximal power density, and 90mA/cm2 maximal current density were obtained.