LiFePO4/石墨烯有序插层复合物的纳米自组装合成与性能研究

磷酸铁锂材料中锂离子在一维通道中沿b轴方向移动，这种一维扩散方式对于锂离子的传输在结构上是一个限制，是影响磷酸铁锂材料倍率性能的重要原因。本项目针对磷酸铁锂材料的一维扩散本质，设计了一种新型的有序插层结构模型，将取向性的磷酸铁锂与石墨烯这种新型的碳材料应用于插层结构中，突破结构上的限制，使锂离子的扩散方式由传统的一维扩散转变为三维扩散，从而提高磷酸铁锂材料的锂离子扩散速率和电子导电率。将纳米自组装技术应用到这种特殊的纳米插层结构合成中。通过系统地研究反应过程,理解自组装过程的作用机理与磷酸铁锂晶体的成核生长机理，实现有序插层结构的可控合成，研究材料结构变化对电化学性能的影响。通过本项目的研究，将实现纳米自组装技术制备有序插层结构理论和方法上的突破，提出改善磷酸铁锂材料倍率性能的新途径，为新型磷酸铁锂插层结构在锂离子电池中的应用奠定基础。

Lithium ion transport is along the b-axis in LiFePO4. The one-dimensional diffusion mode is a great obstacle for lithium ion transportation which is the key point for high rate capacity of LiFePO4. According to the one-dimensional diffusion mode, a layer-by-layered structure is designed by using anistropical LiFePO4 nanoplate and graphene sheet. The layer-by-layered structure could significantly improve lithium ion diffusion rate and electron conductivity, since a three-dimensional diffusion is performed instead of the traditional one-dimensional diffusion mode. In order to get the layer-by-layered nanostructure, self-assembling technique is applied. The reaction processes should be systematically investigated to understand the reaction mechanism of self-assembling process and the formation mechanism of LiFePO4 crystals and successfully synthesize layer-by-layered nanocomposites with controlled morphology. Moreover, the electrochemical properties of the layer-by-layered nanocomposites should also be studied. This project would develop the self-assembled technique both theoretically and practically with the aim of controlled synthesis of self-assembled LiFePO4/graphene layer-by-layer nanocomposites. The successful synthesis of this nanostructure may provide a new strategy of improving the high rate properties of LiFePO4, indicating the potential applications of LiFePO4/graphene layer-by-layer nanocomposites as a cathode materials for lithium-ion battries.