| Solid oxide fuel cells (SOFCs) are solid-state electrical devices that convert the chemical energy of reaction directly into electrical energy. SOFC possesses several distinct advantages, such as high conversion efficiency, environmental friendship and broad adaptive fuels, which is a new green energy and has been paid close attention to extensively. At present, the study of SOFC focuses on how to achieve the normal function of cells in low-to-intermediate temperature zone, reducing the working temperature from1000℃down to a temperature between500℃and800℃. Two effective ways of reducing the working temperature of SOFCs are available: developing novel electrolyte materials with high conductivity rate of oxygen-ion in low temperature and fabricating the electrolyte into membranes in structure. The groups’ previous study showed that Bi2O3doped YSZ could improve the conductivity rate of oxygen-ion of the electrolyte and that the preparation of anode-supported electrolyte SOFC could efficiently reduce the internal resistance of electrolyte, which could lead to a higher output power density. The following researches have been carried out in the paper.The experiment firstly studied on the preparation of Bi2O3doped YSZ electrolyte materials via gel-casting method, discussing the effect of solid content and dispersant content to the rheological behavior of the casting slurry and the effect of issues such as monomer content, solid content and the proportion of monomer cross-linker agents to the flexural strength of the green body prepared via gel-casting. The strength of the green body prepared reached37.56MPa when the slurry met the optimized parameters below:the proportion of AM and MBAM was15:1, the monomer content was10wt%and the solid content was43vol%.The experiment also studied on the properties of NiO/YSZ as the anode supports of anode-supported electrolyte SOFC, analysing the effect of the content of pore-forming agent and NiO to the conductivity of the anode and its micro-topography. When the content of the pore-former was10wt%, the porosity of the anode after reduction process reached41%in which the pore distributed uniformity with good connectivity. The conductivity of the anode prepared under this condition reaches723s/cm. When the NiO content was50wt%, the porosity of the anode after reduction process was about19%higher than the one before reduction.Bi2O3was doped in the traditional NiO/YSZ anode in the experiment. The paper discussed the effect of the addition of Bi2O3to the properties of the anode. The study showed that when the content of the pore-former was10wt%, the addition of proper amount of Bi2O3had no detrimental effects on the conductivity of the anode. Reducing the sintering temperature down to1300℃, the comparison of the SEM image of the cross section of the anode before and after reduction process showed that the pore in the one after reduction distributed more uniformly, in which the pores formed by the burning of the pore-former and those caused by the reduction of Ni in sintering process both had a uniform distribution, adequately meeting the requirement of anode materials.Bi2O3doped YSZ electrolyte membrane was prepared on the surface of anode substrates via slurry spin coating method, and the parameters were optimized. Compact electrolyte membrane integrated well against the anode was obtained when the sintering temperature was reduced down to1300℃. The effect of issues such as solid content of slurry, spin coating time and spin coating speed to the thickness of the electrolyte membrane. Compact electrolyte membrane with a thickness of20μm was obtained under the following parameters:the solid content of the slurry was30wt%, the spin coating time was20s and the spin coating speed was2000r/min, repeating the spin coating process for4times. More cycles of spin coating processes would bring thicker electrolyte membrane. One time of spin coating fabricated a electrolyte layer with a thickness of5μm. |
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