Na3V2(PO4)2F3@C团簇材料自组装合成及结构调控研究

Na3V2(PO4)2F3 cathode material has become the preferred material for energy storage battery electrode materials due to its high potential platform, high energy density, and stable structure, but its conductivity is low and its rate-performance is terrible, which greatly limits its application. The project carried out the following scientific research on the bottleneck problem: based on the surfactant-macromolecular soft matter clusters as the templates, the synthesis of Na3V2(PO4)2F3 cluster materials with specific exposed crystal faces is realized, to improve the problem of the lower reaction kinetics; due to the theory of the defect chemistry, the sodium-deficient/sodium-rich or vanadium-deficient/vanadium-rich structure by non-stoichiometric regulation is realized, to improve its electronic conductivity and ion diffusion coefficient; Through the plasma-induced nitrogen or sulfur deep doping to reduce the band gap of Na3V2(PO4)2F3 and reduce ion diffusion activation ability, simultaneously, control the surface electron and microstructure of the carbon coating, which is significantly increase the reversible specific capacity and high rate performance for the target material. Through the macroscopic and microelectrochemical behavior combined with the law of phase change, the characteristics of crystal structure and the influence of sodium storage performance are deeply analyzed. The research of this project will provide a preliminary scientific research basis for the controllable preparation of cluster materials and the theoretical basis and energy storage application for solving the intrinsic defects of polyanion electrode materials.

Na3V2(PO4)2F3正极材料因电位平台高、能量密度大、结构稳定等优点成为储能电池电极材料的优先选择，但电导率低，倍率性能差，极大地限制了其应用。本项目针对该瓶颈问题开展以下科学研究：基于表面活性剂-大分子软物质团簇为模板，实现特定暴露晶面Na3V2(PO4)2F3团簇材料的合成，改善材料电极反应动力学过慢问题；基于缺陷化学理论，通过非化学计量调控实现缺钠/富钠型或缺钒/富钒型结构，提高其电子电导率和离子扩散系数；采用等离子体诱导氮或硫深度掺杂，降低Na3V2(PO4)2F3带隙，减少离子扩散活化能，同时实现碳包覆层表面电子和微观结构的调控，显著提高目标材料的可逆比容量及高倍率性能。通过目标材料在宏观和微观电化学行为结合材料物相变化规律，深入分析晶体结构特点和储钠性能影响规律。本项目研究将为团簇材料的可控制备及解决聚阴离子型电极材料本征缺陷提供理论依据和储能应用提供前期科学研究基础。

Na3V2(PO4)2F3是一种具有高电位平台、高能量密度的极具应用前景的钠离子电池正极材料。基于开发一种高性能钠离子电池的目的，本项目通过系统研究，针对Na3V2(PO4)2F3电导率低、倍率性能差等缺点，制备了一系列Na3V2(PO4)2F3钠离子电池正极材料。采用水热法，通过调控乙二醇含量，制备了一种多级团簇空心微球结构的Na3V2(PO4)2F3以改善离子扩散特性；使用聚乙烯吡咯烷酮作为表面活性剂，制备了一种均匀多孔的Na3V2(PO4)2F3微球，通过调节聚乙烯吡咯烷酮含量，调控Na3V2(PO4)2F3微球的形貌和表面结构；进一步，使用十二烷基苯磺酸钠作为表面活性剂额、二甲基甲酰胺作为溶剂，协同制备Na3V2(PO4)2F3团簇微球。基于晶体生长理论，深入研究团簇材料磷钼酸作为晶体生长控制剂调控Na3V2(PO4)2F3晶体的生长。通过DFT计算证明磷钼酸可以改变晶面的吸附能，从而诱导晶体定向生长，构筑钠离子迁移的连续通道。基于晶体缺陷理论，通过Zr掺杂的方式研究了储钠机理及离子扩散动力学。针对多价态金属离子的不同特性，利用不同价态Mn离子对此进行进一步深入研究。此外，通过B掺杂碳包覆策略进一步改善电极的极化现象。另外，为了实现多种策略同步实现，采用羧甲基纤维素作为多功能添加剂同步实现自体钠补充、表面改性以及交联碳包覆三种功能。本项目对聚阴离子型Na3V2(PO4)2F3材料的可控制备以及团簇材料在储能领域的应用提供了相应的科学依据和技术支持。