熔融水合盐中新型磷酸盐电池正极材料的设计合成、结构与电化学性能研究

The development and application of new cathode materials for the battery is one hotspot in new material research presently. However, as one bottle-neck, the lack of the effective designed synthetic method for these materials hinders the quick development of this field. In the previous experiments, we found that some ordered structural fragments of the precursors could exist stably in the melting hydrated salt system and participate in the formation of new structures. This gives rise to the special structural relationship between the new compound and the precursors. Apparently, it is possible to achieve the structural regulation and designed synthesis for the new compounds via such structural relationship. Based on the previous study, therefore, we will designed synthesize the novel phosphates containing Li+ or Na+ ions with a layed or porous structure in the melting hydrated salt system through choosing the precursors with suitable structures in this project. At the same time, the electrochemical property of these new compounds will also investigated. By studying the main form and the assembly of such fragements in the melting hydrated salts, we will discover the law and the forming mechanism of such structural relationship between new compounds and precursors. By the comparison of new compound structures and characterizations, the structural relationship between precursors and new compounds will be further identified, and the relation among the crystal structure, synthetic process and the electrochemical property would be summarized. These will lay the foundation of the designed synthesis for new cathode materials in molecular level.

新型电池正极材料是当今材料研究的热点，然而目前能有效实现正极材料用新化合物的设计合成方法还非常欠缺。申请者研究发现，前驱体的链状或层状有序结构片段，能在熔融水合盐的独特介质环境中稳定存在，并通过参与新结构的构建，使前驱体与新化合物间产生结构关联，而借助这种关联可实现具有特定结构新物相的设计合成。本项目拟基于前期研究，以金属磷酸盐为研究对象，通过合理设计与选择前驱体结构，在熔融水合盐中开展含Li+或Na+的具有层状或孔道结构新化合物的设计合成与电化学性能研究；同时，借助原位测试与间歇实验方法，探究前驱体的有序结构片段在熔融水合盐反应中的存在形态、组装规律和调控机制，揭示新物相与前驱体间结构关联产生的内在机理，并通过大量结构与电化学性能对比，进一步归纳新物相与前驱体的结构关联规律，初步建立熔融水合盐中晶体结构、合成工艺和电化学性能间的联系，从而为从分子水平设计合成新型正极材料奠定物质基础。

新化合物的设计合成是目前晶体化学领域的一个热点和难点。本项目基于熔融水合盐这一独特的反应介质，通过选择合适的前躯体化合物，开展了新物相的合成与结构表征工作。先后合成出了多个新物相，通过结构对比，进一步证实了所合成化合物与前躯体间明显的结构关联性。同时，研究还发现不仅前躯体一维链状结构可以在反应介质中稳定存在，而且孤岛状基团也在反应介质中也能保持稳定的排列形态，可作为结构模板诱导新物相的生成。另外，对于外来反应基团，不仅单一阴离子基团可进入前躯体结构中参与反应，而且两种阴离子基团可同时进入前躯体结构参与新结构构建。这些研究结果不仅进一步阐明了熔融水合盐反应体系的作用机理，而且也拓展了熔融水合盐反应体系的应用范围，因而具有一定的理论价值。除此之外，我们基于有机-无机层状前躯体的原位热解反应还开展了新型金属氧化物/碳复合材料的制备研究，并考察了其作为电池负极的电化学性能。研究发现在热解过程中，在层间空间限域效应和有机-无机基团相互作用下，产物具有变化各异的微观结构与形貌，从而成为一个可控制备新型功能材料的新方向，具有较好的研究价值与前景。