锂离子电池负极材料纳米石墨烯的电化学性能研究

Electrochemical Study of Nanographene as Anode Materials for Lithium Ion Batteries

李振刚

11749095

硕士

材料物理与化学

王湘麟

2019-05-20

2019-07-10

哈尔滨工业大学

深圳

可再充电锂离子电池已经被广泛应用于生活中各个方面。随着智能时代的到来，急需研发出新型储锂材料以满足高能量大功率储能器件的要求。就锂离子电池负极碳基材料而言，商用锂离子电池负极材料石墨因理论比容量低而严重限制了整个锂离子电池电化学性能的提高。石墨烯本身作为锂离子电池负极在充放电过程中因结构重新堆叠从而导致比容量的迅速下降。并且通过“自上而下”的方法制备的石墨烯不能实现精确的结构控制，阻碍在原子或分子水平上的结构-性能关系的研究。纳米石墨烯、富勒烯等碳族同素异形体因其特殊的分子结构和边缘构型而备受关注。本文通过有机合成制备了3D纳米石墨烯HBC-3-COOH和C60(OH)12/GO复合物作为锂离子电池负极材料，二者表现出良好的循环性能和出色的倍率性能。（1）通过有机合成制备了具有自组装结构的3D纳米石墨烯HBC-3-COOH，HBC-3-COOH具有大的层间距和独特的纳米洋葱结构。HBC-3-COOH作为锂离子电池负极材料以0.2 A g-1的电流密度恒电流充放电循环100圈后，3D纳米石墨烯HBC-3-COOH的可逆放电比容量高达为844 mAh g-1；以小电流密度为20 A g-1充放电时，3D纳米石墨烯HBC-3-COOH的可逆比容量可以保持在211.1 mAh g-1，3D纳米石墨烯HBC-3-COOH出色的电化学性能与自组装大的层间距和独特的纳米洋葱结构有关。纳米洋葱结构有助于电极与电解液界面的充分浸润，提高了HBC-3-COOH电极材料中锂离子扩散和电子迁移速率，增加了电极的可逆循环性能和倍率性能。该工作表明通过有机合成方法可以制备具有明确结构和不同官能团的高容量锂离子电池负极材料。（2）我们制备了C60(OH)12和C60(OH)12/GO复合材料并应用于锂离子电池负极。结构表征表明GO的羧基和环氧基与C60(OH)12纳米粒子的羟基之间发生化学反应，促使C60(OH)12均匀生长在GO纳米片表面上。使用一系列光谱表征表明了C60(OH)12和GO在分子水平上的混合，有助于C60(OH)12/GO复合材料表现出优异的电化学性能。这种新型C60(OH)12/GO复合材料在0.2 A g-1时的可逆容量为1596 mAh g-1，高于C60(OH)12和GO的容量。该复合材料具有良好的循环稳定性和优异的倍率性能，使其有望成为高性能锂离子电池的负极材料。本工作表明C60衍生物可作为一种高效的储锂材料，同时为改善氧化石墨烯基负极材料提供了一种新途径。

The rechargeable lithium-ion batteries (LiBs) have been widely used in energy storage applications in all aspects of our life. With the advent of the intelligent era, it is urgent to develop new lithium storage materials to meet the requirements of high-energy/power density energy storage devices. As for anodes of LiBs, the commercial anode, graphite severely limits the electrochemical performance of entire LiBs due to its low theoretical capacity (372 mAh g-1). Graphene anodes experience a significant irreversible capacity loss during charging/discharging cycles, due to restacking of graphene layers. And graphene prepared by the "top-down" method cannot achieve precise structural control, hindering studies of structure-property relationships at the atomic or molecular level. Nanographene and fullerene are carbon allotropes, they have attracted much attention due to their special structure and edge configuration. In this thesis, 3D nanographene HBC-3-COOH and C60(OH)12/graphene oxide (GO) composite synthesized by organic synthesis as anode electrode materials for lithium ion batteries, they exhibited good cycling stability and excellent rate performance.3D nanographene HBC-3-COOH with self-assembled structure was prepared by organic synthesis, and HBC-3-COOH had large d-spacing and unique nano-onion structure. HBC-3-COOH as lithium ion battery anode materials at a current density of 0.2 A g-1, after charged and discharged 100 cycles, the reversible discharge specific capacity of 844 mAh g-1 can be achieved; At a current density of 20 A g-1, the reversible specific capacity can still be maintained at 211.1 mAh g-1. The excellent electrochemical performance of 3D nanographene HBC-3-COOH is related to the large d-spacing of nanographene and the unique nano-onion structure. The nano-onion structure can provide sufficient wettability of the interface between the electrode and the electrolyte, accelerate the diffusion of lithium ions and electron migration rate in the HBC-3-COOH electrode material, and improve the reversible cycle stability and rate performance of the 3D nanographene HBC-3-COOH electrode. This work indicates that high capacity anode materials with precise structures and different functional groups can be prepared by organic synthesis methods.We report synthesis and characterization of the C60(OH)12 and C60(OH)12/graphene oxide (GO) composite, and demonstrate their use towards anode materials in LiBs. We found the C60(OH)12/graphene oxide (GO) composite were prepared due to the chemical reaction between the carboxyl and epoxy groups of GO and the hydroxyl of C60(OH)12 nanoparticles, which the C60(OH)12 were uniformly grown on the surface of graphene oxide nanosheets. Using a suite of spectroscopic probes, we shown unequivocally the mixing between C60(OH)12 and GO at the molecular level, which leads to superior battery performances. This new type of composite exhibits a reversible capacity of 1596 mAh g-1 at 0.2 A g-1, higher than the capacities of C60(OH)12 and graphene oxide, respectively. This composite shows good cycling stability and excellent rate performance, making it promising anode material for high performance lithium ion batteries. This work demonstrates that C60 derivatives can be a highly efficient Li storage materials, and provides a new way to improve the graphene oxide anode material.

锂离子电池 负极材料 纳米石墨烯 氧化石墨烯

C60(OH)12 lithium ion battery anode nanographene；C60(OH)12 graphene oxide

中文

联合培养

南方科技大学

李振刚. 锂离子电池负极材料纳米石墨烯的电化学性能研究[D]. 深圳. 哈尔滨工业大学,2019.