LiMnPO4·Li3V2(PO4)3/Graphene复合材料的表面交联沉积可控制备的基础研究

As members of phosphate system, LiMnPO4 and Li3V2(PO4)3 cathode material both have a wide application in the field of lithium ion power battery with their superiority of high discharge capacity and good safety performance. However, to make this real we need to clear away two main rocks, the low electronic conductivity and the poor large current discharge performance of the two materials. Aiming at this program, this study using Graphene oxide (GO) as matrix, combing with partial manganese vanadate (MnV2O6•2H2O) grown up on it by the surface- crosslinking -deposition method as the precursors(MnV2O6•2H2O/GO) to prepare LiMnPO4•Li3V2 (PO4)3/Graphene composites. Through this method, the ionic conductivity can be improved with the fast ionic conductivity of Li3V2(PO4) 3 and the Mn2+/V3+ part mutually doped LiMnPO4• Li3V2 (PO4) 3. At the same time, the performance of layered graphene excellent electronic transmission can improve the electrical conductivity of the composite material. After clarifying the relationship between the structure and performance, the conclution of Mn2+/V3+ doping mechanism of each other and the transport mechanism in the composite materials which broaden the development of lithium ion power battery cathode materials and the effective utilization of domestic rich manganese and vanadium resources in our country.

LiMnPO4和Li3V2(PO4)3同属磷酸盐体系正极材料，具有放电容量高和安全性能好等优点，在锂离子动力电池领域具有广泛的应用前景。但这两种材料的电子导电率低，大电流放电性能差，限制了其应用。本研究针对该问题，以氧化石墨烯(GO)为基体，结合表面交联沉积技术制备氧化石墨烯上原位生长的偏钒酸锰(MnV2O6•2H2O)，进而合成LiMnPO4•Li3V2(PO4)3/Graphene复合材料。一方面利用Li3V2(PO4)3的快离子导电性以及Mn2+/V3+相互掺杂来提高复合材料的离子导电性；另一方面利用层状的石墨烯优异的电子传输性能来改善复合材料的电子导电性。通过对复合材料结构和性能的研究，阐明结构和性能之间的关系，得出Mn2+/V3+相互掺杂的作用机理以及锂离子在复合材料内的传输机制，为锂离子动力电池正极材料的开发以及国内丰富的锰和钒资源有效利用提供了新的发展思路。

通过液相共沉淀法合成MnV2O6•4H2O和MnV2O6•4H2O/GO前驱体，并喷雾干燥法合成了LiMnPO4·2Li3V2(PO4)3/C 和LiMnPO4·2Li3V2(PO4)3/G，得到的LiMnPO4·2Li3V2(PO4)3/G复合材料性能更加优异，倍率性能和循环性能均有所提高。一方面利用Li3V2(PO4)3的快离子导电性以及Mn2+/V3+相互掺杂来提高复合材料的离子导电性；另一方面利用层状的石墨烯优异的电子传输性能来改善复合材料的电子导电性。通过对复合材料结构和性能的研究，阐明结构和性能之间的关系，得出Mn2+/V3+相互掺杂的作用机理以及锂离子在复合材料内的传输机制。