【作者】 丁姣；

【导师】 刘江；

【作者基本信息】 华南理工大学 ， 应用化学， 2010， 博士

【摘要】 固体氧化物燃料电池是一种将化学能直接转化为电能的装置,具有能量转化效率高、环境友好及燃料选择范围广的优点,是21世纪各国竞相发展的一种新型绿色能源,越来越受到研究者们的重视。降低工作温度,开发中低温SOFC已成为当前SOFC商业化发展的必然趋势。阳极支撑型电解质膜电池是近年来中温固体氧化物燃料电池(IT-SOFC)研究的热点之一。减小电解质膜的厚度,制备膜电解质阳极支撑型固体氧化物燃料电池是降低电池工作温度(600～800℃)、降低电池制作成本、保持电池输出性能、延长电池寿命的有效方法之一。因此,开发低成本高效率的阳极支撑型固体氧化物燃料电池制备工艺是固体氧化物燃料电池产业化和商业化的重要途径。本论文首先开发了料浆喷涂法制备阳极支撑型电解质膜工艺。在多孔NiO-YSZ阳极支撑体上采用料浆喷涂法成功制备了YSZ电解质膜,研究了YSZ喷涂料浆的制备,探讨了料浆喷涂法的工艺技术,总结了料浆喷涂法的方法和技巧,并对电池的电化学性能进行了测试和分析。研究结果表明,YSZ喷涂料浆的悬浮性和均匀性对料浆喷涂法制备YSZ电解质膜有直接影响。采用料浆喷涂法成功制备了15μm厚的YSZ电解质膜,其单电池开路电压在600℃时已经达到1V以上,以LSM-YSZ为阴极在800℃以下的中温区工作时性能优异,800℃时以氢气为燃料最大输出功率密度达到了0.99W／cm2。本文研究了用于低温固体氧化物燃料电池(400℃～600℃)的具有高导电性能的新型电解质材料：Sm0.2Ce0.8O1.9(SDC)。在料浆喷涂法制备电解质膜工艺的基础上,在扣式NiO-SDC多孔阳极支撑体上制备了SDC电解质膜,并制备了单电池,对电池性能进行了测试和分析。比较了SDC粉体三种合成方法对料浆喷涂法制备SDC电解质膜结构和电池输出性能的影响。结果表明,柠檬酸-硝酸盐法制备的粉体适合用于料浆喷涂法制备SOFC的电解质膜。采用柠檬酸-硝酸盐法合成的SDC粉体制备的电解质膜和电极(包括阴极和阳极)接触良好,电解质表面没有气孔和裂纹,仅在膜截面有少量闭合气孔,电池开路电压可以达到0.9V左右,基本满足固体氧化物燃料电池运行的需要。本文研究了阳极中Fe的掺杂,利用Fe部分取代Ni,降低了电池的制作成本。采用甘氨酸-硝酸盐燃烧法成功地合成了Ni1-xFexO(x=0.01,0.04,0.08,0.1,0.15,0.2,0.4,0.5)阳极粉体,并制备了扣式Ni1-xFexO-YSZ阳极支撑型YSZ膜电解质固体氧化物燃料电池。对单电池在氢气和甲烷燃料下的性能进行了测试,并对该种阳极上的碳沉积进行了分析。结果表明,用少量的Fe来取代Ni有利于改善阳极微观结构,延长了电池反应的三相界面,有利于电池的电化学反应,提高了电池的输出性能。并且在阳极中掺杂少量Fe可以减缓碳沉积现象,延长电池的运行寿命,对阳极的稳定性十分有利。本文将传统的陶瓷成型工艺—注浆成型法引入阳极支撑体的制备中,详细探讨了影响注浆成型工艺的各种因素,确定了注浆成型法制备长管状阳极支撑体的工艺参数：使用10%～15%阿拉伯树胶作为分散剂；pH值为4～5；原料粉体的球磨时间为2小时,分散剂阿拉伯树胶的球磨时间为20分钟；采用甘氨酸-硝酸盐燃烧法合成氧化镍原料粉体。并采用注浆成型法成功地制备出长管状阳极支撑体,进而制备成单电池。采用加湿氢气为燃料,测试了注浆成型法制备的长管状阳极支撑型YSZ膜电解质SOFC单电池的性能,该单电池在850℃时最大输出功率密度为0.907W／cm2,证明了注浆成型工艺制作方法优良,操作简单,价格低廉,是一种制备固体氧化物燃料电池的可选工艺。本文在注浆成型法制备长管状阳极支撑体的基础上制备了锥管状阳极支撑体,采用浸渍法制备了阳极功能层和YSZ电解质膜,进而把单电池采用串接方式组成电池组。并对单电池及电池组的微观结构和电化学性能等进行了研究。结果表明,阳极功能层的引入有效减少了电解质膜厚,增大了三相反应区,提高了电池的输出性能。该电池在750℃和800℃的最大功率密度分别达到1.32W／cm2和1.78W／cm2。800℃时,该电池的欧姆电阻为0.04Ωcm2,极化电阻为0.14Ωcm2。引入阳极功能层后,电池的欧姆电阻和极化电阻都减小,有效地改善了界面情况。成功组装了由两个单电池组成的电池组。该两电池组在800℃下,开路电压为1.7V,在电流为3A的情况下,最大输出功率约为2.64W。并且该两电池组经历了12次热循环,开路电压和最大输出功率稳定,没有出现明显的衰退,能够经受住重复启动考验。本文在电解质薄膜化,降低电池的工作温度,从而降低电池成本的基础上,重点研究了阳极支撑型YSZ膜电解质固体氧化物燃料电池的一步烧结工艺,进一步降低电池成本。考察了一步烧结工艺制备的单电池的电化学性能。结果表明,YSZ电解质的烧结致密性是一步烧结工艺的关键。综合比较了四种烧结程序制备的电池测试后横截面和YSZ电解质膜表面的微观结构,电池阳极孔隙率和收缩率,及单电池开路电压和电池输出性能等方面。确定了一步烧结制备锥管状阳极支撑型固体氧化物燃料电池的最佳程序为先以1℃／min从室温升到400℃,在400℃保温1小时；然后以2℃／min升到1000℃,在1000℃下保温2小时。最后,再以2℃／min升温至1300℃,并保温2小时。更多还原

【Abstract】 Solid oxide fuel cells (SOFCs) are solid-state electrochemical device that convert the chemical energy of reaction directly into electrical energy. It possesses several distinct advantages, such as environmental friendship, higher conversion efficiency and broad adaptive fuels, which is a new green energy developed in the world for 21st century and attracting more and more attentions of researchers. It is necessary to lower the operation temperature and develop the intermediate SOFCs (IT-SOFCs)for the commercialization of SOFCs. Reducing the thickness of electrolyte to prepare the anode-supported electrolyte film SOFCs is an effective approach to lower the operation temperature and reduce the cost of SOFCs while to retain the high performance and extend the life-span of SOFCs. Therefore, development of cost-effective fabrication technology of anode-supported SOFCs is a key step for the industrialization and commercialization of SOFCs.Colloidal spray coating technique was developed to fabricate Y2O3-stabilized ZrO2 (YSZ) electrolyte thin films onto NiO-YSZ porous anode substrates. The important technological parameters of colloidal spray coating, including the preparation of YSZ suspension and the skills of the technology, were investigated in detail. The results showed that the properties of the YSZ suspension exerted a significant effect on the microstructure of the YSZ films. 15μm-thick YSZ film was successfully coated on the anode substrate by colloidal spray coating. Cells with dense YSZ film provided open-circuit voltage (OCV) of over 1V above 600℃, which is very close to the OCV calculated by Nernst equation. The maximum power density of the cell based on YSZ film using La0.8Sr0.2MnO3 (LSM)-YSZ composite cathode is as high as 0.99W/cm2 at 800℃using humidified hydrogen as fuel and ambient air as oxidant.Anode-supported SOFCs with Smo.2Ce0.8O1.9 (SDC) electrolyte films were fabricated by colloidal spray coating technique as described above and tested using CHI604B electrochemical instrument. Three kinds of SDC powders used to fabricate SDC electrolyte films were synthesized by glycine-nitrate process, citrate-nitrate method and solid-state reaction, respectively. The microstructure of SDC films and the performance of the single cell were compared. The results showed that SDC powders which had been synthesized by citrate-nitrate method were suitable for preparing electrolyte films by colloidal spray coating technique for SOFCs. SDC film and the electrodes contacted well, and the surface of the sintered SDC film was crack-free while there were some pinholes in the cross section. The electrochemical test results revealed that the cell based on SDC film can provide OCV as high as 0.9V.It is an effect approach to reduce the preparation costs of SOFCs by partially replacing Ni with Fe in the anode. Ni1-xFexO (x=0.01,0.04,0.08,0.1,0.15,0.2,0.4,0.5) anode powders were synthesized by glycine-nitrate process (GNP). The single cells consisted of Ni1-xFexO-YSZ anode, YSZ electrolyte film, LSM-YSZ composite cathode were prepared and tested at the temperature from 600℃to 850℃with humidified hydrogen and methane (75ml/min), respectively, as fuel and ambient air as oxidant. The results showed that the cell performance had been improved by partial substitution of Ni with Fe. And the cell with Ni0.9Fe0.1O-YSZ anode showed the highest power density,1.238W/cm2 at 850℃, among the cells with different anode composition. It was found that Ni1-xFexO-YSZ anode might decrease coking, extend the life of the cell and maintain the stability of the anode.A simple and cost-effective slip casting technique was successfully developed to fabricate NiO-YSZ anode substrates for tubular anode-supported single SOFCs. The key technological parameters of slip casting were investigated in detail. The results showed that the optimum technological parameters of slip casting were using 10wt%～15wt% Arabic resin (balata) as dispersant; pH with 4～5; ball milling the raw materials for 2 hours; ball milling the Arabic resin (balata) for 20 minutes and using glycine-nitrate process to prepare NiO. A single cell, NiO-YSZ/YSZ(20μm)/LSM-YSZ, using the tubular anode support with YSZ coating, was assembled and tested to demonstrate the feasibility of the techniques applied. Using humidified hydrogen (75ml/min) as fuel and ambient air as oxidant, the maximum power densities of the cell were 760mW/cm2 and 907mW/cm2 at 800℃and 850℃, respectively. The results proved that slip casting technique may be promising for tubular anode substrate fabrication.The cone-shaped tubular anode substrates were fabricated by slip casting technique based on the technique as mentioned above. And the YSZ electrolyte films were deposited onto the anode tubes by dip coating method. A two-cell-stack based on the above-mentioned cone-shaped tubular anode-supported SOFC was fabricated by invaginating one by one. Its typical operating characteristics were investigated, particularly with respect to the thermal cycling test. The results showed that the single cell with anode functional layer, NiO-YSZ/YSZ (7μm)/LSM-YSZ, provided a maximum power density of 1.78W/cm2 at 800°C, using moist hydrogen (75ml/min) as fuel and ambient air as oxidant. And the ohmic resistance of the cell was 0.04Ωcm2 the polarization resistance was 0.14Ωcm2。Both the ohmic resistance and the polarization resistance of the cell were reduced by introducing the anode functional layer. The two-cell-stack presented an open circuit voltage (OCV) of about 1.7V and a maximum output power of 2.64W (1=3A) at 800℃. The two-cell-stack had experienced twelve periods of thermal cycling test and showed good thermo-mechanical properties. The developed segmented-in-series SOFC stack is highly promising for portable applications.Anode-supported cone-shaped tubular solid oxide fuel cells were successfully fabricated by a single-step cosintering process. The key facts of single-step cosintering process, which significantly influences the characterization of YSZ electrolyte and electrode, including sintering procedure and highest sintering temperature were investigated. The results showed the microstructure and dense property of YSZ was the key step in single-step cosintering process. Cell electrochemical test results and scanning electron microscope graphs showed that the optimal procedure for the single cone-shaped tubular SOFCs was that, first raising the temperature to 400℃with a heating rate of 1℃/min and dwelling at 400℃for 1 h, and then raising to 1000℃with 2℃/min and dwelling there for 2h, finally raising to 1300℃with 2℃/min and dwelling for 2h.更多还原