磁取向技术制备高容量LiFePO4动力电池及其稳定性计算研究

全球石油危机日益严重，用电池驱动汽车成为了汽车行业的一个共识。动力汽车发展的主要瓶颈就是动力电池正极材料的可行性研究问题。前期研究发现，CeO2能够促进LiFePO4电极材料的高温安全稳定性、锂离子扩散系数及电化学性能。本课题在前期工作基础上，通过对磁场取向技术的研究，获得成熟的C包覆和CeO2掺杂改性LiFePO4水热合成技术路线，实现磁场下掺杂型LiFePO4微纳米单晶颗粒的b轴方向的择优取向，掌握控制晶粒形貌特征和粒径大小的关键技术，解明这些微纳米颗粒的定向排布机理，考察不同工作温度下结构－性能之间的关系，阐述其微结构对电子传导及脱/嵌锂机理的影响规律，探讨锂离子的扩散能力对引起容量衰减的反占位缺陷的影响，有望进一步提高LiFePO4的比容量和不同工作温度下快速循环特性，为设计和构筑新型高性能电极材料提供有力的理论和技术支持，进而实现该材料在动力电池方面的应用。

The global oil crisis is serious nowadays, electric automobile has become a consensus. The main problems for the development of electricmobile is feasibility of the cathode in lithium ion battery. In our study, CeO2 should improve the comprehensive properties of the LiFePO4 materials for lithium ion batteries at elevated temperature and larger scan rates. Based on our previous work, the orientation of the magnetic field technology and hydrothermal synthesis are used to prepare the C-coating and CeO2-modified LiFePO4 particles. Micro-nano LiFePO4 single crystal particles along the b-direction are obtained to master key technology on control of grain morphology and particle size, to explain these particle orientation mechanism, to consider the relationship between structure and properties of different working temperatures and the effects of the microstructure, electron conduction and lithiation and delithiation mechanism. The research on antisite defects in LiFePO4 that may affect the diffusion behavior is expected to further improve the electrochemical performances of LiFePO4 on different working temperatures and rapid cycle characteristics. Our research provide a strong theoretical and technical support for the design and construction of new high performance electrode material and then realize the material for power battery applications.