运行条件下新型自愈合SOFC封接玻璃的调控及稳定性研究

The Solid Oxide Fuel Cell (SOFC) is considered to be in the 21st century new energy technologies. It is an important way to achieve clean energy, low-carbon development. Commercial SOFC stack need to be run 40, 000h and more experienced several thermal cycles. How to ensure the SOFC stack sealing glass of the long-term stability is a crucial issue in the commercialization process. In this project, the periodicity potential-field of microcrystalline in the sealing-glass was utilized to limit the diffusion of the net ligand ions. The competition mechanism for the net-format was used, when the low melting point microcrystalline was introduced, which could control the crystallization of glass-ceramic and the self-healing property in high temperature. The relationship between the glass composition and properties of glass was researched and the crystallization kinetics equation was established under long-term working temperature. The introducing additives and ligand ions of glass-net forming the competitive reactions, thus it will inhibit the interfacial reactions between seal-glass and metallic connecting materials. The reaction mechanism and the changing relationship between the sealing condition and running time of SOFC stack. The questions of failure for SOFC stack, which were produced due to the changes of the expansion coefficient and changes of the viscosity and the interfacial reactions of SOFC sealing-glass, were solved. Through the testing keeping SOFC stack running for one thousand hours, the running state of the sealing-glass of the stack during operating for several ten thousands hours, could be predicted well.

固体氧化物燃料电池（SOFC）被认为是21 世纪的新能源技术，是实现能源清洁化、低碳化发展的重要途径。商业化SOFC电堆需运行40, 000h以上并经历数次热循环，如何保证SOFC电堆封接玻璃的长期稳定性是其商业化进程的关键问题之一。本项目利用玻璃中微晶的周期性势场限制网络配体离子的扩散以及通过网络形成体竞争析晶机制，控制SOFC封接玻璃的析晶并使其具有高温自愈合性，研究该玻璃组成与性能间的关系并建立玻璃在长期工作温度下的析晶动力学方程；引入添加物，改善玻璃网络中的配体离子性质，从而抑制封接玻璃与金属连接板的界面反应，阐明封接玻璃与金属连接板界面的反应机制以及封接状态随运行时间的变化关系。拟解决SOFC封接玻璃长期在工作温度下因析晶带来的热学性能变化及界面反应等所产生的电堆封接失效的问题。通过对SOFC电堆千小时内运行的考查，预测数万小时运行期间电堆内封接玻璃的工作状态。

中温固体氧化物燃料电池是一种将燃料与氧化剂中的化学能直接转换为电能的全固态发电装置，提高封接材料的热稳定性是平板式IT-SOFCs商业化应用的关键因素之一。本项目围绕有产业化前景的富钡硼铝硅酸盐封接玻璃在IT-SOFCs工况下的热稳定性能展开研究，主要研究内容和获得的重要结果为：B2O3的引入降低了玻璃的致密化温度，改善SCBA系玻璃在8YSZ电解质表面的润湿性。在封接温度（1073K）下，SCBA系玻璃析出了钡长石晶体，且与8YSZ电解质的结合性良好；在BSCA系封接玻璃中，参与玻璃网络成键的网络形成体Al2O3可以有效增强玻璃的网络结构，提高玻璃的析晶活化能，降低封接玻璃的热膨胀系数。抑制了BSCA玻璃内析出的BaAl2Si2O8晶体由六方相向单斜相的转变，减少热膨胀系数的下降，从而提高了BCAS系列封接玻璃的热稳定性；基于BSCA1玻璃的差热分析结果，通过非等温结晶动力学研究了BSCA1的析晶动力学指数n，并用两种不同方法进行相互论证，均计算出BSCA1玻璃的平均动能指数n值≈1，说明该玻璃在热处理过程中晶体表面成核且向外一维生长；为直接避免钡长石从富钡硼硅酸封接玻璃中析出，BCBS封接玻璃中析出的主晶相Ba1.55Ca0.45SiO4未随热处理时间的延长而改变。晶体的含量变化对封接玻璃本身的热膨胀系数无明显影响，该系数值一直维持在11.15×10-6 K-1左右，处于SOFC实际封接要求范围内；SrO的引入可以定程度提高玻璃的网络结，抑制六方钡长石的晶型转变构，使得玻璃热处理前后始终保持非晶态，提高了封接玻璃的稳定性，说明混合碱土金属效应有利于抑制玻璃的析晶及晶型转变；利用溶胶-凝胶法制备SOFC封接玻璃，并于固相熔融法进行对比。溶胶-凝胶法制备的封接玻璃内部网络结构更加均匀（提高玻璃的热稳定性）且熔融温度低100-150°C，可以明显降低制备成本和提高玻璃的质量。