纳/微米分级结构LiMnPO4可控构筑及其嵌锂性能调控研究

Nano/micro hierarchical structure could enlarge the area of electrode reaction and shorten the diffusion path of lithium-ion in the solid state. Moreover, it could assimilate the volume change stress for the intercalation/deintercalation of Li+, and make full use of the electrochemical lithium intercalation performance. Therefore，it is regarded as an ideal electrode structure for Li-ion battery..The project will adopt hydrothermal(solvothermal) method to prepare LiMnPO4 nanostructures unit, and utilize the spatially anisotropic during self-assembly process to construct nano/micro hierarchical cathode materials, such as three-dimensional network structure, porous structure, flower-like structure etc.. By systematically investigating the influence of solution composition and reaction conditions on the structures and morphology of materials, discussing the mechanism of nucleation and growth, revealing the laws of thermodynamics and kinetics of the assembly process to achieve hierarchical assembly structure (time) and dynamic control..Through charge/discharge testing of the as-synthesized materials, to inspect the influence of the structure, morphology on the electrochemical lithium intercalation performance; Mn element of LiMnPO4 material will partially replaced by Ni, Co, V etc., in order to tune lithium intercalation kinetics and discharge voltage platform, and expand the application prospect of material. Furthermore, advanced characterization methods will be employed to explore the“Structure-Activity”relationship. This study will provide a synthesis route for high-performance LiMnPO4, and theoretical guidance for exploring novel lithium intercalation cathode materials. Thus, this work has important value for both basic and applied research.

纳/微米分级结构能够提高电极反应面积和缩短离子固相扩散路径，缓解材料嵌/脱锂的体积变化应力，能促使材料性能充分发挥，被视为理想的锂离子电池电极结构。.本项目拟采用水（溶剂）热法制备LiMnPO4纳米结构单元，利用自组装过程空间各向异性，构筑具有三维网状、多孔状、花状等纳/微米分级结构正极材料。通过系统研究溶液组成和反应条件对材料结构、形貌的影响，探讨晶体的成核和生长机理，揭示组装过程的热力学和动力学过程规律，实现组装体结构的分级（时间）与动态调控。.通过对所合成材料进行充放电测试，考察结构、形貌对其嵌锂性能的影响；采用Ni、Co、V等元素部分取代Mn来调控材料的嵌锂动力学性能和放电电压平台，开拓材料的应用前景；并应用先进表征手段探讨材料的“构-效”关系。本研究将为完善LiMnPO4材料制备科学提供数据支撑，为探索新型高性能嵌锂阴极材料提供理论指导。因此，具有重要的应用和基础研究价值。

本项目采用水/溶剂热法制备LiMnPO4纳米结构单元，利用自组装过程空间各向异性，构筑具有晶面取向的纳/微分级结构阴极材料；通过系统研究溶液组成和反应条件对材料形貌结构的影响，探讨晶体的成核和生长机理，实现组装体结构的分级（时间）与动态调控；并考察形貌结构对其嵌锂性能的影响；在上述研究基础上，采用Fe、Ni、Co、V、Ti等元素部分取代Mn调变材料电子跃迁带隙及嵌锂能垒，提高材料充放电性能。主要研究结果有：1）采用灵活可控溶剂热合成途径制备得到LiMnPO4/C纳米片，详细讨论了采用柠檬酸，葡萄糖和蔗糖不同有机碳源添加对LiMnPO4/C纳米复合材料结构和电化学性能的影响；2）采用乙二醇、甘油、聚乙二醇400、聚乙二醇600等有机溶剂作为反应的前驱体溶剂，有机溶剂通过有效调节形态，尺寸和晶体取向生长在LiMnPO4/C材料的形成中起重要作用；3）采用微波辅助溶剂热法制备得到LiMn1−xMgxPO4/C，样品为具备较大比表面积和介孔结构的片层状形貌材料，Mg2+掺杂在晶体合成过程中发挥着重要作用，提高电极材料的电化学活性和电化学性能表现。本研究开发高性能LiMnxM1-xPO4/C复合正极材料，适用于大规模生产，具有重要的理论和实用价值。