阳极支撑SOFC电解质薄膜及电极材料的制备与性能研究

发布时间：2018-04-02 12:31

  本文选题：固体氧化物燃料电池　切入点：NiO/YSZ阳极　出处：《山东大学》2017年硕士论文

【摘要】：固体氧化物燃料电池(Solid oxide fuel cell,SOFC)是新型绿色发电技术,采用离子导体为隔膜,直接将化学能转化为电能,能量转换效率高,安全环保,很有发展前景。然而其工作温度较高会引发诸多问题,降低SOFC的使用寿命和工作效率,实现电池中低温化的常用方法就是采用阳极支撑SOFC,将电解质材料制备成薄膜。作为SOFC的重要组成部分,阳极支撑体与电解质薄膜的性能极为重要。首先以石墨为造孔剂制备多孔NiO/YSZ阳极材料,探讨造孔剂含量对阳极材料微观结构及各项性能的影响。结果表明随着造孔剂含量的增加,阳极材料的开气孔率和收缩率等逐渐增加,抗热震性能得到改善,而其弯曲强度和电导率有所降低。其中石墨含量1Owt%的阳极材料,弯曲强度在50MPa左右,还原后气孔率达到38%,电导率为720s/cm,满足SOFC正常工作的基本要求。其次通过干压成型法制备出梯度阳极材料,使阳极从支撑层到功能层NiO和造孔剂含量递减,原料粉体颗粒逐渐细化,孔隙率降低,从而增加阳极的催化活性,使阳极材料工作寿命延长,性能提高。对于阳极功能层,原料球磨时间越长,则粉体颗粒越细,混合越均匀,从而保证了较高的反应三相界面。然后采用浆料旋涂法在阳极支撑体上制备电解质薄膜,研究各项旋涂工艺参数对电解质薄膜厚度和致密性的影响。发现粘结剂中乙基纤维素含量为3wt%,固相含量为40wt%,阳极预烧温度为800℃时,薄膜致密性较好。旋涂时间为20s,转速4000r/min,旋涂4次时,可以得到厚度15um左右的电解质薄膜。薄膜厚度均匀平整,与阳极支撑体连接紧密。在YSZ浆料中加入Bi203作为烧结助剂,不仅可以降低烧结温度,提高致密性,还能促进晶粒生长,降低电解质材料的晶界电阻。但过多的Bi2O3会导致部分c-ZrO2转变为氧离子电导率较低的m-ZrO2,同时降低了电解质的抗热震性能。添加3wt%Bi2O3的YSZ电解质在125℃时的相对密度为97.5%,达到纯YSZ电解质在1450℃烧结后的致密性,避免了 m-ZrO2的生成,较为合适。最后采用溶胶凝胶法制备出比表面积较大、反应活性较高的钙钛矿型LSM阴极粉体。将LSM与YSZ混合,球磨时间越长,粉体混合越均匀,颗粒越细小。通过旋涂法在阳极支撑电解质上制备复合阴极薄膜,可得到SOFC单电池。浆料中乙基纤维素起到粘结剂和造孔剂的双重作用,其含量为6wt%的复合阴极在110℃烧结后骨架结构细化,孔隙细小均匀,薄膜表面平整,且与电解质接触紧密,使阴极拥有更多的三相界面,电化学活性提高。
[Abstract]:Solid oxide fuel cell (SOFC) is a new type of green power generation technology, which uses ionic conductor as the diaphragm, converts chemical energy directly into electric energy, has high energy conversion efficiency, and is safe and environmentally friendly. It has a bright future. However, its high working temperature will lead to many problems and reduce the service life and efficiency of SOFC. The common way to realize low temperature in battery is to use anode to support SOFCs, and make electrolyte materials into thin films, which is an important part of SOFC. The properties of anodic support and electrolyte film are very important. Firstly, porous NiO/YSZ anode materials are prepared by using graphite as pore-forming agent. The effect of the content of pore-making agent on the microstructure and properties of anode materials is discussed. The results show that the opening porosity and shrinkage rate of anode materials increase gradually with the increase of pore-making agent content, and the thermal shock resistance of anode materials is improved. The bending strength and electrical conductivity of the anode material with graphite content of 1 Owt% decreased, and the bending strength of the anode material was about 50MPa. After reduction, the porosity is 38 and the conductivity is 720s / cm, which meets the basic requirements of SOFC normal operation. Secondly, gradient anode materials are prepared by dry compression molding, and the content of NiO and pore-forming agent decreases from the supporting layer to the functional layer. The particle size of the raw material gradually refines and the porosity decreases, thus increasing the catalytic activity of the anode, prolonging the working life and improving the performance of the anode material. For the anode functional layer, the longer the milling time of the raw material is, the finer the powder particle is, and the more uniform the mixing is, Thus a high reactive three-phase interface is ensured. Then the electrolyte film is prepared on the anode support by slurry spin coating method. The effects of various spin-coating process parameters on the thickness and densification of electrolyte film were studied. It was found that when the content of ethyl cellulose in binder was 3 wt, the solid content was 40 wtand the anodic prefiring temperature was 800 鈩，

本文编号：1700431