锂离子电池负极用硅/石墨烯纳米复合材料的原位合成和性质模拟

Sustainable alternative energy sources have been widely pursued due to the limited supply of tranditional fossil energy souces (oil, natural gas and coal) and their detrimental effects on the global environment and climate. However, the Li-ion rechargeable bettery has played a vital role in fast developing market to the portale electronic device and electic vehicle. The performance of batteries, including energy density, cyclabilty, and safety, are required to be enhanced to atisfy the increasing demand of new application. These properties are directly related on structure of the material. The recent research reported the silicon is one of the most attractive anode matersial for advanced Li-ion battery (LIB).. In the present proposal, we attempt to illustrate the relationship between the structrue of Si/graphene nano-composite and its physicochemistry properites by first-priciples calculation and molecular dynamics simulation. Meanwhile, the results from the computation would help us to design and systhesize better Si/graphene composites for LIB anode materials. Experimentally, we will fabricate noval intercalation-type nano Si/graphene composites and investigate the phsical chemistry property, especially their electrochemistry property. It should be noted that the nano-structure composites are synthesized by synchronous synthesis means. Using modern testing methods to investigate the the different physicochemical and structural properties of Si/graphene composite which are obtained with different Si sources and preparation condition. The theoretical and experimental results from the present proposal will provide technological support for the industrial application of Li-ion battery equipped with Si/graphene composite anode materials.

作为最重要的新型能源材料之一的锂离子电池在经济和生活的各个领域获得了极其广泛的应用，研究和开发高性能的锂离子电池也成为了目前新能源材料的热点。其中，电极材料的研究和开发是使锂离子电池得到有效利用的一个关键。本申请课题从研究新型的硅基锂离子电池负极材料出发，探讨硅/石墨烯复合材料的制备科学及储锂材料的构效关系，进而为高性能锂离子电池的研究提供支持。本申请课题采用量子化学的第一性原理结合分子动力学方法，研究不同结构的硅/石墨烯复合材料的性质，特别是对其电化学性能进行考察, 从而阐明硅/石墨烯复合材料结构特征和储锂性能之间的内在关系。同时，根据理论模拟的结果，采用同步合成技术制备“插层式”硅/石墨烯复合负极材料，通过现代表征技术考察不同硅源和不同制备方法得到的硅/石墨烯复合材料的物化性质和特征，获得影响此类材料性能的关键制备科学和工艺条件，为其工业化应用提供技术支持和理论指导。

各种移动电源的广泛使用，人们对于锂离子电池的性能提出了更高和更严格的要求，因此开发性能更好的锂离子电池变得十分重要。本项目探索了不同结构、形貌，不同制备方法等合成的硅碳材料的储锂机制，扩宽了硅碳材料在锂离子电池负极材料领域的研究；设计并制备了具有长循环性能和高容量的Li2FeSiO4/C, SiOx-Si/rGO/PPy, SiOx-G/PAA-PANi/graphene, SiOx-G/PAA-PANi/Cu等材料，通过各种表征和测试方法深入研究储锂机制。例如，我们的测试表明，合成的Li1.95Na0.05FeSiO4/C和Li2FeSiO4/C复合材料拥有较好的稳定性，比容量达到110 mAhg-1，在2C条件下循环100周后依然有97.8%的比容量，这表明稳定性极高的碳在实现硅材料高容量的长循环方面有着突出作用。这些工作为硅碳复合材料在储能领域的研究提供了指导。同时，我们在理论研究上，探讨了BC2N，Ti3N2材料，石墨烯/MoSSe等二维材料形成的具有异质结的嵌脱锂性能以及作为锂离子负极材料的应用前景。我们对于BC2N材料的计算表明，其最大嵌锂容量可以达到547 mAhg-1(其开路电压为0.32 V), 大于石墨烯的372 mAhg-1。我们的研究还表明，T3N2和MoSSe等二维材料与石墨烯形成异质结构时，会显著改善复合材料的嵌锂性能，并具有更好的锂等碱金属原子的迁移性能。这些研究工作为今后此类材料的应用提供了基础指导。