基于低共熔溶剂制备钠离子电池纳微结构Na2Ti3O7/C负极材料

The electrochemical performance of nano/micro-structured electrode materials is highly dependent on the crystal structure and morphology. Furthermore, the crystal nucleation, growth and its structure evolution are determined by the reaction and mass transfer characteristics during the preparation process . . This proposal will focus on “how to design and control the micro-structure of nano/micro-structured Na2Ti3O7/C and improve its electrochemical performance?”. First, the correlation between the micro-structure and the electrochemical properties of nano/micro-structured Na2Ti3O7/C will be studies. Second, we will introduce the structure parameters as control index, and the effect of microcosmic processes，such as reaction, mass transfer, crystal nucleation and growth on the material nano/micro-structure, will be quantitative description using the principle of multiphase reaction kinetics theory and its research methods. And the strategy of controlling the micro-structure of nano/micro-structured Na2Ti3O7/C which is synthesized by ionothermal-thermol process will be presented. At last, we will quantitative analysis the interaction among the preparation parameter, the micro-structure and the electrochemical performance of Na2Ti3O7/C using optimization methods. In addition, the method of design and control the crystal structure, particle morphology and the electrochemical properties of nano/micro-structured Na2Ti3O7/C at a macro scale of operation parameters will be presented. . The results of this proposal not only will improve the scientific theory which can accelerate the preparation and practical application of nano/micro-structured Na2Ti3O7/C anode material, but also provide a new idea on the structure design and performance optimization of electrode material for lithium/sodium ion batteries.

纳微结构电极材料的电化学性能高度依赖于材料的晶体结构和微观形貌，而晶体的成核生长过程和材料微观结构的演化又由制备过程中的反应和传递特性所决定。本项目拟在确定纳微结构Na2Ti3O7/C负极材料微观结构与电化学性能关系的基础上，采用多相反应动力学的原理和研究方法，以材料的微观结构特征参数为控制指标，定量描述合成过程中的反应、传递、成核和生长等微观过程对材料纳微结构的影响，进而提出离子热-热处理法制备纳微结构Na2Ti3O7/C负极材料的微观形态控制策略，最后利用最优化方法建立制备纳微结构Na2Ti3O7/C的工艺条件、材料的结构形貌和电化学性能之间的定量关系，提出在宏观工艺尺度设计和调控晶体结构、颗粒形貌及材料电化学性能的方法。本项目的完成不仅可为纳微结构Na2Ti3O7/C负极的制备和实际应用奠定理论基础，而且也对锂/钠离子电极材料的结构设计和电化学性能优化提供新的研究思路。

本项目采用低成本的低共熔溶剂热法，在温和条件下获得了具有较好电化学性能的Na2Ti3O7等钠/锂离子储存材料，并开展了如下方面的研究：.（1）在分析Na2Ti3O7材料的形成机制的研究基础上，确定了Na2Ti3O7负极材料的制备工艺参数、产品微观结构与电化学性能的关系，优化了合成工艺，获得的Na2Ti3O7材料具有较为出色的循环稳定性，并进一步研究了上述材料在充放电过程中的动力学行为。.（2）将多壁碳纳米管与Na2Ti3O7材料进行原位复合，制备了珊瑚状Na2Ti3O7@CNTs材料，为Na+的嵌入/脱出提供了大量的吸附位点，测定并分析了组装的AC// Na2Ti3O7@CNTs钠离子混合电容器的充放电性能，可为钠离子电容器的研究提供参考。. 总之，在三年项目实施期内，课题研究基本按照原计划执行，有部分研究内容根据实际情况稍作调整。研究取得了一些成果，所采用的低共熔溶剂介质中温和制备的方法对锂/钠离子电极材料的合成提供了新思路，具有一定的应用前景。