梯度结晶构筑氧化物复合空心微球及其电化学性能研究

Metal oxides microspheres with a characteristic hollow structure have shown tremendous potential in a wide spectrum of application areas such as lithium ion batteries, catalysis, and biomedical engineering. In this contribution, we aims to develop a versatile synthetic platform, which not only effective for a large variety of materials but also with key evidence in support of the growth mechanism identified, for the preparation of inorganic hollow microspheres. Starting from the controlled formation of uniform microspheres of a unique organic/inorganic precursor, which has a relatively low crystallinity, we’ll try to enforce the creation of hollow cavity right inside the solid particles by simply controlling the crystallization gradient particle: Particles firstly crystallize on the surface, and then the crystallization gradually proceeds inwards, leading to depletion of the core and simultaneous formation of cavity. We’ll focus on the detailed structural change during this progressive-inward-crystallization process. By means of different characterization techniques including focused ion beam (FIB) and high resolution transmission electron microscopy (HRTEM), we’ll do research on the detailed formation mechanism during the formation and development of defects and cavity inside the solid microspheres, leading to a clear understanding on the hollowing process. The achievement of the synthesis control is expected to produce different inorganic hollow microspheres with good control on different parameters such as the compositions, the textiles, and the porosity. By using these well-defined inorganic hollow microspheres as model systems of structurally-controlled electrode materials, we’ll try to inquest the relationship between their structures and battery performance. Combined with the data from detailed characterizations on the medium state of the electrode materials during the charge/discharge cycle, we expect to have a better understanding on the working mechanism of lithium ion batteries. An optimized structure of the electrode materials made of metal oxide hollow microspheres is expected to be disclosed. We expect that our findings in these hollow microspheres offer new perspectives in different areas ranging from materials chemistry, energy storage devices, catalysis, and drug delivery.

无机金属氧化物及其复合物的空心结构在电极材料、催化、医疗等不同的领域展现了广阔的应用前景。本项目将致力于新合成方法的研究和探索，基于一种特殊的表面梯度结晶的方式，开发适用于一系列不同金属氧化物及其含碳复合物空心结构制备的通用合成方法。相关研究将从制备均一的有机/无机前体出发，通过控制实心颗粒表面由外至内依次结晶的方式，调控颗粒内部的应力并促进空腔的形成；同时，通过对材料结构的精确解析，在原子尺度上获得材料形貌演化过程中颗粒内部缺陷产生、生长及调控的机制；结合电化学性能测试和电化学中间反应过程的详细表征，系统研究空心电极材料结构属性与其电化学性能之间的构效关系，促进电极材料循环性能、倍率性能等应用指标的提升。相关的在合成方法学、空心结构的控制及形成机理、结晶学、材料电化学性能优化等方面具有重要的科学意义和实践价值。

空腔结构材料具有独特的结构特征和物化特性，在诸多领域中具有广阔的应用前景。通过对空腔壳层的组分、结构、表面特性的合理调控，可以实现功能材料的特性化设计从而满足相关的应用需求。对于锂离子电池电极材料而言，充分利用空腔结构在电解液浸润、锂离子传输、复合结构设计方面的优势，构筑具有空腔结构的微纳复合材料已经成为提高电极材料倍率性能及稳定性的有效途径。从材料制备的角度出发，如何克服传统空腔结构构筑中存在的工艺繁琐、耗时长、污染严重、成本高等挑战，基于新的机理和路径实现电极材料空腔结构的大规模可控制备，成为基础研究的重要课题。. 本项目基于对空腔结构材料空腔形成机制及应用过程中存在的基础科学问题的思考，聚焦于合成方法学上的研究与创新，获得了一系列基于非模板过程构筑空腔结构材料的方法：相关研究从具有特定结构的实心颗粒构筑出发，先构筑具备较低结晶度的实心微球前体，进而结合高温处理控制颗粒的结晶过程，控制颗粒内部径向结晶度的变化，在内部诱导应力的产生从而促成缺陷的形成和生长，无需外界模板获得了空腔结构，同时，通过在空腔演化过程中材料自身结构的精确解读，从原子级层面上获得颗粒内部缺陷产生、生长及调控的机制，获得了基于颗粒内部结晶度调控快速、高效、大量构筑空腔结构的新方法；在此基础上，本项目进一步扩充了这种基于实心颗粒内部化学属调控构筑空腔结构的方法，确认基于颗粒内部分子量、组分等不同因素调控均可以实现空腔结构的精准构筑。.从空腔结构材料的构筑出发，结合材料自身结构、组分等关键因素的调节，建立开展电化学应用研究的模型材料体系，并结合电化学性能测试和电化学中间反应过程的表征，系统研究了空腔电极材料与其电化学性能的构效关系，促进了电极材料循环性能、倍率性能等关键指标的显著提升。相关研究，在合成方法学、空心结构的控制及形成机理、结晶学、材料电化学性能优化等方面具有重要的科学意义和实践价值。