定向结构β″-Al2O3电解质离子传导的织构强化效应及电化学稳定性研究

Development of oriented β″-alumina ceramic has the important significance to improve the ionic conductivity and high stability of β″-Al2O3 electrolytes. The conventional solid state reactions process leaves double structure and composition segregation, which lead to unstability of conductivity. Based on a unique topotaxial effect and texture effect of oriented β″-alumina ceramic electrolytes, this project will use hydrothermal synthesis method to prepare precursor, then microwave sintering assisting ice-templating synthesis highly oriented β″-alumina. The process and mechanism of ice template induced nano precursor directionally aligning are studied. The effect of precursor microstructure, additive, freezing parameters and sintering parameters on the grain size, crystal orientation, phase, ionic conductivity and mechanical properties of β″-alumina ceramic electrolytes are studied. And it also illustrate the influence mechanism of microstructure on the properties of β″-alumina ceramic electrolytes, further reveal the mechanism of microstructure on the topotaxial effect and texture reinforcement of electrolytes. Meanwhile, the complex impedance method will be used to study the aging behavior of grain and grain boundary, fracture failure analysis will also be used to reveal the failure mechanism and its influence on the electrical stability. The research results will bring new insight for application of high ionic conductivity and high stability β″-Al2O3 electrolytes.

研制具有定向结构的β″-Al2O3对提高电解质材料离子电导率及电化学稳定性具有重要的意义。传统固相反应法制备的β″-Al2O3，易产生双重结构、成分不均匀，导致性能较差及不稳定。本课题在研究具有定向排列的电解质独特Topotaxial效应和织构强化效应基础上，拟采用水热合成前驱体及微波辅助冰晶模板制备高取向性β″-Al2O3电解质材料。研究冰晶模板诱导纳米前驱体定向排列的过程及机理，并研究前驱体形貌、添加剂、冷冻参数、烧结参数对β″-Al2O3电解质晶粒大小、取向度、相含量、电导率和力学性能的影响规律。阐明微观结构对电解质性能的影响规律，并进一步揭示微观结构对电解质织构强化、Topotaxial效应作用机制。利用电化学阻抗谱法检测电解质晶粒和晶界的老化性能，结合断裂失效分析，探索取向结构电解质材料的失效机制及对其稳定性影响规律。研究成果为高电导率、高稳定性的电解质材料的应用奠定基础。

研制具有定向结构β″-Al2O3电解质对提高电解质材料离子电导率及电化学稳定性具有重要的意义。传统固相反应法制备的β″-Al2O3，易产生双重结构、成分不均匀，导致性能较差不稳定。本项目采用水热合成的一维纳米结构薄水铝石前驱体为铝源，结合冰晶模板诱导一维纳米材料定向排列成功制备出具有高取向度、高离子电导率、高力学性能的β″-Al2O3电解质材料。系统研究了水热参数、前驱体形貌、烧结参数、稳定剂等对β″-Al2O3电解质的微观形貌、β″-Al2O3相含量、取向度、离子电导率及力学性能的影响。结果表明：当预烧温度为1100 ℃时，高温烧结后材料中β"-Al2O3相含量最高可达96.12%，取向度为0.21，电导率为6.59E-2 S·cm-1。引入冷冻干燥后取向度提高到0.38，电导率达1.852E-1 S·cm–1。采用SPS压力烧结能显著提高材料取向度，最大达0.74，棒状β"-Al2O3陶瓷样品在垂直于单轴压力方向的电导率为1.83×10-1 S·cm-1，弯曲强度为250 MPa。冷冻干燥辅助SPS烧结后β"-Al2O3陶瓷中相含量、取向度、电导率均有一定下降，经1600℃二次热处理后电导率达到2.34×10-1 S·cm-1。该研究为高电导率β"-Al2O3隔膜材料的产业化发展提供理论指导及依据，为更广泛的应用奠定了坚实的科学基础。