锂离子电池充放电曲线斜坡化的磷酸锰铁锂复合正极材料构建及其结构与性能的构效关系研究

To solve the problem that the state of charge (SOC) of Li-ion batteries with LiFexMn1-xPO4 cathodes cannot be accurately measured by simply measuring voltage, this project proposes the measure that optimizing the composition and controlling the structure of the anode material to achieve inclining charge/discharge curve of the battery. This project proposes to construct LiMnxFe1-xPO4/Li2FeSiO4/C composite cathode material, utilizing the nanocarbon network to improve the conductivity of LiMnxFe1-xPO4 and Li2FeSiO4. The formation mechanism, the relationship between the structure and the electrochemical properties of the material, the influences of composition and structure towards charge/discharge curve and the electrochemical process will be investigated. The results will lead to the optimization of the composition and structure of the composite and thus lead to the production of LiMnxFe1-xPO4/Li2FeSiO4/C composite with high energy density, excellent electrochemical performances and inclining charge/discharge curves (which would allow the determination of SOC by simple voltage measurements). By solving this common problem of poly anionic phosphate cathode materials, large-scale application of lithium manganese iron phosphate cathode materials and the development of electric vehicles will be highly boosted.

针对磷酸锰铁锂电池剩余电量（SOC）不能简单地通过测量电压进行准确测算的问题，提出采用优化正极材料组成和调控结构的办法，实现电池充放电曲线的斜坡化，以解决该问题。构建LiMnxFe1-xPO4/Li2FeSiO4/C复合正极材料实现充放电曲线斜坡化。主要利用无定型碳、碳纳米管和石墨烯构成的复相碳纳米网络解决LiMnxFe1-xPO4和Li2FeSiO4导电性差的问题。通过研究该材料的形成机制、结构与电化学性能之间的构效关系对充放电曲线斜坡化的影响规律及其电化学过程，指导组成和结构的调控，实现对制备过程的有效控制，制备出能量密度高、化学性能优异及其充放电曲线斜坡化的LiMnxFe1-xPO4/Li2FeSiO4/C正极材料，实现通过简单地电压测量就可以准确测算磷酸锰铁锂动力锂离子电池SOC的目的，解决聚阴离子磷酸盐正极材料的共性问题，推动磷酸锰铁锂正极材料的规模化应用，促进电动汽车的发展。

在项目期间，主要研究了LiFePO4镍掺杂及镍在线催化石墨化碳包覆层共改性、Y-F共掺杂对LiFePO4/C复合材料的结构及其电化学性能影响、LFP/C/G/CNTs复合材料的制备及电化学性能、导电剂构建碳导电网络提升磷酸铁锂倍率性能、LiMnxFe1-xPO4/Li2FeSiO4/C复合正极材料的制备、结构与电化学性能之间的构效关系及其对充放电曲线斜坡化的影响规律进行了系统研究。结合LiMnxFe1-xPO4和Li2FeSiO4二者的优势，通过构建复相碳纳米网络，制备出能量密度高、化学性能优异及其充放电曲线斜坡化的LiMnxFe1-xPO4/Li2FeSiO4/C正极材料。实现了对磷酸锰铁锂电池剩余电量（SOC）不能简单地通过测量电压进行准确测算的问题。并在2Ah铝塑膜软包装锂离子电池中进行了验证。推动了磷酸锰铁锂正极材料在新能源船舶的规模化应用。