【作者】 孙雪丽；

【导师】 孙俊才；

【作者基本信息】 大连海事大学 ， 载运工具运用工程， 2007， 博士

【摘要】 固体氧化物燃料电池（SOFC）是一个将燃料中的化学能直接转换为电能的发电装置。可应用于船舶等载运工具的动力装置和辅助推进装置，实现绿色交通。其燃料可以是化石燃料气、生物质气和其它碳氢化合物。SOFC的能量转换是通过电极上的电化学反应来进行的，避免了NO_x、SO_x、CO、CO₂以及粉尘等污染物的产生；SOFC在提供电力的同时，还可以提供高质量热，实现热电联供；其能量转化效率可以高达85％。但是，传统的SOFC通常在800℃-1000℃的高温工作，由此带来诸多问题，包括材料选择、制造成本昂贵等等缺点，因此降低SOFC的工作温度成为当前实现SOFC商业化面临的首要任务。固体氧化物燃料电池操作温度的中低温化（300-800℃）是固体氧化物燃料电池走向商业化的发展趋势，目前的研究工作主要集中在600-800℃中温区。然而随着温度进一步降低，可以大幅地降低燃料电池制造成本，更加有效地扩大电池连接和密封材料的选择范围以及延长电池的使用寿命，使其更具有商业化前景。但是这方面的研究国内外相对较少，尚属于起步阶段。本文主要为发展在300-600℃这一温度工作的低温SOFC，开发满足这一需求的新型电解质和与之匹配的高性能阴极材料，以期获得高的电池性能。从复合两相材料角度出发，构筑并合成制备了掺杂铈基氧化物与碳酸盐组成的复合电解质体系，研究表明：该复合电解质体系可以实现在低温区达到0.1S/cm的高离子电导率。以20SDC（80wt％）-NLCO（20wt％）为优选复合比例构成的复合电解质，两边涂铂浆构成固体氧化物燃料电池单电池，在400℃下的开路电压达到1.0V、单电池最大功率密度为272mWcm^-2。在钙钛矿类型阴极材料研究基础上，设计并发展合成了新型钙钛矿型阴极材料La-Ni-Cu-O（LNC）系列化合物，对材料的结构，晶格常数，粉体表面形貌特征和构成单电池的电池性能进行了综合评价，认为适量Cu的掺杂有助于提高阴极材料的催化活性、提高电导率。以LaNi_xCu_1-xO₃（x=0.2-0.8）为阴极的SOFC单电池在400-500℃下显示了良好的电化学性能，其中LaNi_0.8Cu_0.2O₃在450℃时具有最大功率密度620mW/cm²，开路电压为1.0V。说明LNC材料是一类很有应用前景的低温SOFC阴极材料。为进一步发展新型的低温固体氧化物燃料电池的阴极材料，探索了在高温低氧分压环境下结构稳定并具有金属导电特性的钒酸盐作为低温固体氧化物燃料电池阴极材料的可行性。首次采用固相法合成了SmVO₄及其衍生物Sm_0.5Sr_0.5VO₄，并对两者组织结构和性能进行了研究。结果表明两者均为体心四方结构，Sr对SmVO₄的掺杂几乎不改变其原来的晶型和晶格尺寸。在复合电解质GDC-NLCO电解质体系当中，以SmVO₄材料为阴极，在450-550℃温度范围内，燃料电池的开路电压稳定在0.92-1.04V之间，550℃时最大电流密度达到650mA/cm²，最大输出功率为300mW/cm²。而以Sm_0.5Sr_0.5VO₄作为SOFC单电池的阴极，在SDC-碳酸盐复合电解质体系内，低温电池性能并没有提高。采用聚丙烯酸方法合成了阴极材料Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-σ（BSCF），该材料是目前被认为性能最好的中低温阴极材料之一。与复合电解质组成单电池，在500℃和450℃温度下最大功率密度及最大短路电流密度分别为860 mW/cm²、540.1mW/cm²以及2300mA/cm²和1604mA/cm²。采用复合电解质和BSCF阴极材料，首次成功制备出有效活化面积为14cm²，实际面积为4×4cm的大面积电池片，在510℃时电池输出功率达到5W，相应的输出功率密度达358mW/cm²，获得目前报道的大面积单电池低温下最好的电池性能。更多还原

【Abstract】 Solid oxide Fuel cell is a kind of electricity-generating device which can transform the chemical energy of fuel into electricity directly through the electrochemical reactions happened on both anode and cathode. The fuels include fossil gas, biological gas and other hydrocarbon. The process of the energy transformations is quiet, clean with high efficiency. If high quality heat exhausted was utilized, the total efficiency of energy transfer will be reached more than 85%. For the traditional SOFC, the operation temperature is generally in a relative higher temperature range of 800-1000℃, which causes a lot of problems, such as the materials selection, the manufacture cost, life time, etc. Therefore, the most urgent problem we confronted presently was how to lower down the operating temperature of SOFC and make the commercialization of LTSOFC come true.Recently, realizing the working temperature of SOFC into low or intermediate temperature range （300-600℃） is a major trend, but nearly all the works reported were focoused on the range of intermediate temperature 600-800℃.That further lowering down the operating temperature of SOFC can not only enlarge the selection of materials in the field of both connector and seal cement, but also can prolong the cycle lifetime of operation, realizing a better commercialization. But, there were few research works reported up to now on these issues in the low temperature SOFC. The main target in this paper is to develop new type of cathode material with good catalysis and electrochemical properties and new composite electrolyte for LTSOFC to get a good comprehensive performance of the whole fuel cell.Based on the principle of two phases composite, we designed and successfully synthesized doped ceria-carbonate composite electrolyte. The results showed that this composite system could obtain high electric conductivity of 0.1S/cm within low temperature range. Selecting the optimum 20SDC（80wt%）-NLCO（20wt%） as electrolyte and Pt pasted on both sides as electrodes, the OCV and maximum output power density of the single fuel cell were 1.0V and 272mW/cm² at 400℃, respectively. A new series of La-Ni-Cu-O （LNC） compounds were synthesized as cathode materials and the microstructure and properties of thses compounds were studied. In the La-Ni-Cu-0 compounds, a certain quantity of Cu substitution improved electro-catalystic activity and electric conductivity. The LaNi_xCu_1-xO₃ （x=0.2-0.8） cathode with 20SDC（80wt%）- NLCO （20wt%） as electrolyte, showed good performances in 400-500℃. The OCV and maximum output power density of the single fuel cell with LaN_0.8Cu_0.2O₃ as cathode with the best properties were 1.0V and 620mW/cm² at 450℃, respectively, which meant that LNC is a potential cathode material for LTSOFC.To develop the cathode materials for ILTSOFC further, we explored and investigated the feasibility of vanadium with the characteristics like metal conductivity and stable structure under the condition of low oxygen partial pressure and high temperature as cathode material. Using solid state reaction method the material of SmVO₄ and Smo.5Sro.5VO4 were synthesized then analyzed. The results showed that both of them were body centered tetragonal structure, which indicated that SmVO₄ was well doped by Sr atoms, without changing its original structure and lattice parameters. Using SmVO₄ as cathode, GDC-NLCO as electrolyte to constructure the SOFC unit, the voltages of the fuel cell unit were among 0.92-1.04V, and the maximum current density, the maximum power density were 650mA/cm²、300mW/cm², respectively, at 550°C; While Smo.5Sro.5VO4 was selected as cathode material for LTSOFC, the properties of the fuel cell did not be improved in the system of composite electrolyte and low temperature range.Finally, the Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-（?）（BSCF） perivskite were synthesized by PAA method, which was already considered as one of the best cathode materials for low and intermediate temperature SOFC. The performances of BSCF were investigated in composite electrolyte to make fuel cell. The maximum power density and the maximum current density at 500℃, 450℃were 860 mW/cm², 540.1mW/cm² and 2300 mA/cm² and 1604mA/cm², respectively. Furthurmore, in this work, we successfully fabricated a big fuel cell disk with 14cm² effective area from real area 4×4cm plate, the power of 5W was obtained at 510°C, whose corresponding power density was 358mW/cm², the best power density reported up to now.更多还原