| One of the most effective way to decrease working temperature to low medium temperature, which can solve electrode sintered, interface diffusion between electrolyte and electrode and thermal expansion mismatch under high temperature. The thickness of anode is much more than electrolyte and in anode-supported SOFC, so electrochemical and physical performance of single cell depends on a great extent on the composition and structure of anode. For high quality SOFC anode, in order to ensure high conductivity, high electrochemical activity and high strength, microstructure and porosity is important particularly. The most common, effective and simple method to change microstructure of ande is adding pore-former.First, in this paper,PMMA was prepared by organic glass,different size PMMA was got through different concertration.The result showed that the size of PMMA increased with the concertration. This method is very simple and convenient to get pore-formers of same componets and different size according to different components of SOFC required different porosity.In this paper, animals and plants cells,rape pollen and egg yolk were used as new pore-formers first time. The effect of different morphology,particle size and content of pore-formers on the porosity, mechanical strength and microstructure of anode, the electrochemical properties of single cell have been investigated.Comparing with paper fibre,the result showed, with the same content of pore-formers,the Mechanical Strength of cell adding rape pollen was the worst while the mechanical strength of cell adding paper fibre was the best.After burning of rape pollen,there were some circular cavity with the Diameter of5-10μm in anode.When adding10wt.%rape pollen, there were less dense circular cavity which existed alone and had poor connectivity;when adding more than30wt.%rape pollen,the agglomerated pollen formed large single holes or some big holes connecting each other,which might cause anode structure loose and decrease TPBs and power density.The result showed that the properties of cell with20wt.%rape pollen was best, the total polatized resistance of the single cell was0.635(?)·cm2,and the maximum power density achieved0.782W/cm2at750℃with H2as the operating gas.In the internal parts of anode adding egg yolk,there were a large amount of dense holes with the diameter of1-2μm.It made the fuel flow through each area of anode slowly and uniformly to decrease concentration polarization.Even adding30wt.%pore-former,there were not any excessive holes appeared. Such tiny holes were benefit for ande and electrolyte to combinate closely because there were not too many oversize holes on the interface between they each other.It was found that the performance of cell adding20wt.%egg yolk was the best,the maximum power density was1.110W/cm2,and the electrode polatized resistance was0.391(?)Q·cm2.Using paper fibers as pore-formers in anode of SOFC, linear pores which had moferate size were formed,and the axis of those holes was nearly perpendicular to Electrolyte layer. When NiO:YSZ:paper fibre=5:5:l,which was the optimal ratio,the pores in anode distribute uniformly and link together.The maximum power density is1.097W/cm2, the electrode polatized resistance is0.297(?)·cm2.When continue to adding paper fibre,the porosity of anode was over high,and many pores which paraller to electrolyte layer could be seen,the output power density began to decrease.Furthermore, the best of the cells with three kinds of pore-former had good thermal shock resistance,and the anode and electrolyte matched well with each other.The cells were well flat, which was useful for preparing large area and flat planar anode supported SOFC. |
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