二维异质复合薄膜材料的可控制备及储锂性能研究

As a key component in rechargeable lithium ion batteries, electrode materials play an essential role in the electrochemical performance of the batteries.Thus, it is highly desired to develop low-cost, high performance electrode materials. This project will focus on the design and fabrication of metal dichalcogenide-based layered electrode materials with high theory capactiy. New in situ growth strategies will be developed to generate new metal dichalcogenide/graphene two-dimensional heterostructures. The phase, crystallinity and sheet number of the two-dimensional heterostructures will be well controlled during the synthesis and post-treatment processes. The two-dimensional heterostructures will facilitate the penetration of the electrolyte with the electrode and shorten the diffusion distance of lithium ions and electrons. The graphene nanosheets in situ generated during the preparation processes will enhance the lithium ion and electron conductivities of the two-dimensional heterostructures. Consequently, the specific capacity, the rate capability and cycling stability of these heterostructures will be significantly improved. In situ characterization techniques, such as in situ X-ray diffraction and adsorption, will be employed to investigate the processes of lithium ion intercalation/de-intercalation to elucidate the lithium ion storage mechanism for metal dichalcogenide-based materials and disclose the key factors that impact on the performance of these materials. This research will develop new metal dichalcogenide/graphene two-dimensional heterostructured materials with properties of high specific capacity, good rate capability, excellent cycleability and low cost, and will shed some new light on the mechanism of the reversible lithium ion storage in the metal dichalcogenide-based materials.

电极材料是锂离子电池的关键部分，是提高锂离子电池性能的关键和制约锂离子电池发展的瓶颈。本项目拟以高比容量、廉价的金属硫化物材料为研究对象，通过新的制备路线的开发，原位可控生长金属硫化物/石墨烯二维异质薄膜材料；优化制备和后处理条件，控制金属硫化物的晶相，提高其结晶度，并精确调控异质薄膜材料的堆砌层数，提高材料锂离子迁移率和导电性，达到提高其比容量、改善倍率特性和循环稳定性等电化学性能的目标，推动金属硫化物在锂离子电池电极材料中的实际应用；利用原位X-射线衍射和吸收等在线检测手段研究锂离子电池充放电过程，阐释二维异质薄膜电极材料的储锂机理，为开发容量大、倍率特性好、循环稳定性高和成本低的锂离子电池电极材料进行积极探索。

电极材料是锂离子电池的关键部分，是提高锂离子电池性能的关键和制约锂离子电池发展的瓶颈。本项目以高比容量、廉价的金属硫化物材料为研究对象，通过原位盐模板制备路线，原位可控生长层层堆砌的金属硫化物/石墨烯二维异质薄膜材料；利用静电相互作用，通过层-层自组装的设计，与石墨烯复合制备出钒酸锂/石墨烯电极材料。并通过调控异质薄膜材料的堆砌层数，提高了材料锂离子迁移率和导电性，进而提升了其比容量、改善倍率特性和循环稳定性等电化学性能。在合成的基础上，研究和阐释了电极材料的储锂机制。我们还成功地将本课题开发的研究策略应用到了其他复合电极材料的制备，获得了一系列结构新颖、性能优异的钠离子电池、钾离子电池、超级电容器和锂空气电池电极材料。项目实施过程中，在Angew Chem., Adv. Mater., Adv. Energy Mater., Adv. Funct. Mater., Nano Lett.等国际知名学术期刊上共发表SCI收录论文23篇，影响因子大于10的有9篇，申请并授权了4项国家发明专利。