微纳结构多孔C／NiO复合材料的结构设计与储能特性研究

NiO based materials with high theoretic capacity are good candidates for anode materials of lithium-ion batteries. However, poor electrical conductivity, volume change during charge and discharge and physical disintegration have severely hampered the performance of NiO-based materials as an anode. In order to solve this problem, we propose to prepare micro/nano structured porous C/NiO composite materials as the anode of lithium-ion batteries. The characteristics of the composite materials is that the matrix of the material is carbon, which has a high structural stability and electrical conductivity. Nano-NiO with large capacity is to be evenly distributed in the carbon frame work with empty spaces or pores around them. Graphene with high electrical conductivity and structural stability will be synthesized in situ on the surfaces of composite material. The pores will be used as buffer spaces during charge/discharge, to prevent the destruction of carbon base, hence improving the cycle stability. In this project, we will focus on the preparation of C/NiO composite materials using sol-gel method, SiO2 template method and conventional pyrolysis of organic carbon. After that, graphene is synthesized in situ on the surfaces of the composites to further enhance their conductivity. We also intend to investigate systemically the relationships between the nanostructure, chemical composition and energy storage mechanisms. Furthermore, the intercalation behavior of Li+ in the electrode materials will also be examined to build a theoretical model describing the dynamic behavior of the anode in the charge and discharge process. The project will provide theoretical basis for the design and preparation of new anode materials for lithium-ion batteries of large capacity, high power and long cycle life.

高容量的NiO基材料具有作为锂离子电池负极材料的良好潜质，但是NiO导电性差，并且电池充放电时NiO膨胀和粉化，使其电极性能恶化，为了解决这个问题，本项目提出了通过结构设计，制备微纳结构多孔C／NiO复合锂离子电池负极材料。该复合材料的特点是以结构稳定和电导率高的碳材料为基体，高容量的纳米NiO均匀分散在碳基体中，纳米NiO颗粒周围预留合适的三维空隙，石墨烯原位修饰该复合材料。充放电时NiO的膨胀和收缩发生在周围的小空隙内，防止材料基体被破坏，材料结构稳定性及循环性能得以提高。本项目拟采用溶胶凝胶法、二氧化硅模板法以及有机碳热解法制备材料，进一步通过石墨烯原位修饰提高该复合材料的电导率；研究复合电极材料的显微结构、组成与储能之间的关系，重点研究锂离子在电极中的传输行为；建立该复合负极在锂离子电池充放电过程的动力学模型。本研究将为设计高容量、高功率及长寿命的锂离子电池提供基础理论指导。

NiO由于其高比容量、无毒、价廉、原料丰富等优点倍受关注，是非常有前景的锂离子电池负极材料，但是NiO导电性差，并且电池充放电时NiO膨胀和粉化，使其电极性能恶化，为了解决这个问题，本项目制备了微纳结构多孔C／NiO复合锂离子电池负极材料。该复合材料的特点是以结构稳定和电导率高的碳材料为基体，高容量的纳米NiO均匀分散在碳基体中，纳米NiO颗粒周围预留合适的三维空隙，石墨烯原位修饰该复合材料。充放电时NiO的膨胀和收缩发生在周围的小空隙内，防止材料基体被破坏，材料结构稳定性及循环性能得以提高。本项目采用SiO2以及Mg(OH)2模板包覆方法以及有机碳热解技术制备了纳微结构多孔碳／纳米NiO复合复合材料，进一步通过石墨烯原位修饰提高该复合材料的电导率，研究了三维孔容结构形成的机理，阐明了合成条件对材料的物理化学性能影响。将制备的核壳状多孔NiO/C复合材料作为锂离子电池负极材料，对其进行恒电流充放电测试，循环100次后，放电比容量仍在625.3mAh/g。对材料进行倍率性能测试，当电流密度升高到800mA/g，比容量仍能稳定在400.7mAh/g，显示良好的倍率性能。研究了多孔碳/纳米NiO复合负极材料的储能机理及锂离子的脱嵌规律，本研究为制备高容量、高功率及长寿命的锂离子电池提供了理论基础和实践指导。