三维石墨烯基纳米复合材料制备及其储锂性能研究

Graphitic materials are currently the most widely used anode materials for lithium-ion batteries. However, the development of high energy batteries is restricted by the lower theoretical specific capacity of the graphitic materials. High energy can be gained by using some high specific capacity non-graphitic materials. Whereas, the poor cycle performance of the non-graphitic materials also restricts the application in anode. Graphene, a kind of 2-D carbon material, is a newly discovered material which has high conductivity, high surface area, good flexibility, etc. It is expected to improve the performance of anode materials via combining the nano non-graphitic materials and graphene.This project intends to combine hydrothermal carbon-coating and hydrothermal self-assembling to prepare 3-D graphene nanocomposites. Improve the lithium storage performance by optimizing the structure of graphene-based nanocomposites. The project will focus on the basis of scientific issues in design process and preparation of high-performance graphene-based anode materials. And also the project will explore formation mechanism of the 3-D graphene-based nanocomposites and reveal how chemical composition and the morphology affect the lithium storage. The research results will supply some theoretical basis for the design and fabrication of graphene-based nanocomposites for high performance lithium-ion batteries. The research result will be significative for improving the energy density of lithium-ion batteries.

石墨类碳材料是目前应用最为广泛的锂离子电池负极材料，但其较低的理论比容量限制了高能锂离子电池的发展。高容量非碳负极材料可以极大地提高锂离子电池的能量密度，但其较差的循环性能限制了其应用。石墨烯是新发现的具有高导电性、高比表面积、良好柔韧性等优点的二维纳米碳材料，将纳米化的非碳负极材料与石墨烯复合有望得到高性能负极材料。本项目拟结合水热碳包覆和水热自组装制备三维石墨烯基纳米复合材料，探索石墨烯基纳米复合材料制备新方法。通过优化石墨烯基纳米复合材料的结构，改善其储锂性能。项目将围绕高性能石墨烯基负极材料设计、制备过程中的基础科学问题开展工作，探讨三维石墨烯基纳米复合材料形成机理，揭示石墨烯基纳米复合材料化学组成及结构形貌对其储锂性能的影响规律。研究结果将为锂离子电池用高性能石墨烯基负极材料的设计与制备提供理论依据，对于提高锂离子电池的能量密度具有重要意义。

石墨类碳材料是目前应用最为广泛的锂离子电池负极材料，但其较低的理论比容量限制了高能锂离子电池的发展。高容量非碳负极材料可以极大地提高锂离子电池的能量密度，但其较差的循环性能限制了其应用。石墨烯是新发现的具有高导电性、高比表面积、良好柔韧性等优点的二维纳米碳材料，将纳米化的非碳负极材料与石墨烯复合有望得到高性能负极材料。本项目结合水热碳包覆和水热自组装制备了三维石墨烯基纳米复合材料形成，阐明了三维石墨烯基纳米复合材料形成机理——非碳纳米颗粒在水热条件下先包覆上一层含有羟基等含氧官能团的有机物，非碳纳米颗粒包覆层上的羟基等含氧官能团与氧化石墨烯上的羧基等含氧官能团在一定的条件下发生脱水反应交联起来形成了具有三维网络结构的石墨烯基纳米复合材料，开发了一种三维石墨烯基纳米复合材料制备方法。研究了影响石墨烯基纳米材料结构形貌的影响因素及影响机制，阐明了石墨烯基材料的储锂性能与其化学组成及结构形貌的关系——通过在非碳纳米颗粒表面包覆一层碳可以抑制电解液分解等副反应的发生，因而可以提高材料的循环性能；通过将石墨烯交联形成多孔的三维网络结构，有利于提高材料的离子和电子传导性能，从而可以提高材料的比容量和倍率性能，得到了比容量高、循环的性能优异的石墨烯基纳米复合材料——制备出的石墨烯基负极材料的储锂容量高达1115 mAh g-1 ，恒流充放电循环100次，其比容量几乎没有衰减。本项目的研究结果为锂离子电池用高性能石墨烯基负极材料的设计与制备提供理论依据，对于提高锂离子电池的能量密度具有重要意义。