【作者】 刘杰；

【导师】 贺天民；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2005， 硕士

【摘要】 本文以不同方法合成的SDC 粉体为原料,用胶体沉积法在不同阳极支撑体上制备出SDC 电解质单层膜和SDC-YSZ 双层电解质膜,并对其性能进行了研究。研究结果表明,随烧结温度的升高,SDC 电解质膜的致密化增强,但未达到完全致密化程度。比较而言,1500oC 烧结的SDC电解质膜具有较高的致密性。NiO-YSZ 和NiO-SDC 阳极支撑体上所制备的SDC 膜中,混合粉末所获得的SDC 膜具有较高的电导率。不同的阳极支撑体对SDC 电解质膜的电性能有很大影响。NiO-SDC 阳极支撑上制备SDC 电解质膜的电导率(σ800oC =6.69 ×10-2S/cm)高于NiO-YSZ 阳极支撑上SDC 膜的电导率(σ800oC =1.51 ×10-2S/cm)。因此对于中温电解质材料SDC,NiO-SDC 做阳极支撑体更为适合。由于SDC 和YSZ 两层电解质膜间结合较差,因此尚需改进双层膜的制备工艺和方法,以便获得好的电池性能。更多还原

【Abstract】 A fuel cell is a energy device that converts the chemical energy of the fuel and oxidant directly into electrical energy according to the principle of the electrochemistry. It is regarded as the preferably clean electricity generation technology for 21 century due to its high efficiency and friendship environment.A solid oxide fuel cell (SOFC) is the third generation fuel cell. It has many advantages, such as no problem of corrosion and leakage, long lifetime and wide selectivity of fuels because all the components in SOFC are solid. Traditional SOFC used mostly yttria stabilized zirconia (YSZ) as electrolyte. But the high operating temperature (around 1000oC) can lead to complex materials problems such an electrode sintering, interfacial reaction between electrolyte and electrode. Great efforts thus have been made to reduce the operating temperature by developing new electrolyte with high ionic conductivity over a range of intermediate and low temperature. Because alkaline-earth oxide or rare-earth oxide doped ceria presents higher conductivity compared to commonly used electrolyte materials at lower temperature. It is suitable for application in SOFC as electrolyte over intermediate temperature range. Compared to YSZ, the doped ceria electrolyte materials exhibit higher conductivity, lower activation energy and better matching with electrodes. However, the ceria oxide will be reduction in reducing atmosphere and higher temperature. That is quadrivalent Ce4+ transforms into tervalent Ce3+, leading to electron conductance. This will give rise to short –circuit so that decreases the output power density of SOFC. In view of the advantages both the doped-ceria and YSZ, a thin layer of YSZ is added between doped ceria electrolyte and anode, in order to prevent the reduction of Ce4+, to enhance the cell performance. In this paper, the single layer SDC electrolyte films and the double layer YSZ/SDC electrolyte films on NiO-YSZ anode support were prepared using colloid suspension deposition, respectively. And the SDC electrolyte films on NiO-SDC anode support were also prepared using the same method. The properties of the electrolyte films sintered at 1450, 1480 and 1500oC with different holding times were investigated, respectively. The results show that the density of films is improved with temperature increasing. The films sintered at 1500oC for 5h is much more denser than those sintered at 1450oC for 10h and 1480oC for 8h. However, the complete dense films are no attained. There are many linked holes are observed from the crossing-section SEM photograph. It is mainly caused by the preparation of the films. The forming of those films in this process results from the nature gravity of the particles completely, so the particles is simply stacking together. This must produce porosity between particles, leads to many holes existing in the crossing-section. On the other hand, it’s very difficult to sinter the SDC materials. Therefore, the complete dense SDC films is also difficult to achieve due to the nonuniform and larger size of the SDC powder, which prepared by solid state reaction.The conductivity of each sample at 800 and 850oC is summarized in Table 1. Because the YSZ and SDC is not well sintered together, the conductivity of YSZ/SDC double films is the values of SDC films self and lower than its body conductivity which is 0.1S/cm at 800oC. This is because there are some holes in the SDC films. The existence of those holes blocks the pass of the charge-carrier. Furthermore, the results also show that the conductivities of the SDC film supported on NiO-SDC substrate is higher than those supported on NiO-YSZ substrate. This shows that the conductivity of the SDC films contains the anode contribution. In NiO-SDC, SDC is an electrolyte of low and intermediate temperature. While in NiO-YSZ, YSZ is an electrolyte of high temperature. The conductivity of SDC is higher than that of YSZ over the range of intermediate temperature. Therefore, the conductivity of the SDC films supported on NiO-SDC substrate is higher than that of SDC films supported on NiO-YSZ substrate.更多还原