多环芳烃及其衍生物在二次电池负极材料中的电化学性能研究

STUDY ON THE ElECTROCHEMICAL PERFORMANCE OF POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR DERIVATIVES AS SECONDARY BATTERY ANODE MATERIALS

代鑫鑫

11849253

硕士

材料工程

王湘麟

2020-05-30

2020-07-01

哈尔滨工业大学

深圳

当今，随着化石燃料资源的匮乏、环境问题的凸显和电动车市场的壮大，人们对储能器件的要求越来越高。在各种二次电池中，锂离子电池(LIBs)虽然具有高比能量、高比功率、响应速度快等优点，但锂资源稀缺问题难以从根本上得到解决。钠的化学性质与锂相似，其储量丰富、易于开发且成本低廉的显著优点使得钠离子电池(SIBs)被认为是 LIBs 的有力替代品。现阶段用作 SIBs的负极材料普遍存在循环稳定性差和钠离子扩散动力学缓慢等问题，因此研发出新型储钠电极材料以满足高能量大功率储能器件的要求是当务之急。本文通过 “ 自 下 而 上 ” 的有机合成方法高效制备了多环芳烃六苯并蔻(Hexabenzocoronene, HBC)及其衍生物 HBC-OMe，它们在作为 SIBs 负极材料时，均表现出优异的循环稳定性和倍率性能。利用多种测试方法对目标产物 HBC 进行微观形貌、晶体结构及化学组成的表征，包括 X 射线衍射测试、扫描形貌测试、透射电镜测试和拉曼光谱测试，结果表明 HBC 是由亚微米一次颗粒堆积而成的团聚体，具有丰富的孔隙结构和较大的层间距；采用恒电流充放电测试和电化学阻抗测试评估了 HBC作为 SIBs 负极材料的电化学性能。在 0.1 A g-1 的电流密度下循环 400 圈后，HBC 的可逆充电比容量高达 326 mAh g-1，容量保持率高达 95%，表明其具有出色的循环稳定性；阶梯充放电时，在 5 A g-1 大电流密度下，HBC 仍具有 83mAh g-1 充电比容量；当再次以 0.1 A g-1 的电流密度充放电时，其容量保持率高达 96%。HBC 表现出出色的倍率性能和长循环稳定性，这与其较大的层间距有利于钠离子传输和亚微米颗粒间丰富的孔隙有利于形成能维持结构完整的固态电解质界面(SEI)膜有关。此外，我们还制备了多环芳烃衍生物 HBC-OMe 并用作 SIBs 负极材料。在电流密度为 0.1 A g-1 下，HBC-OMe 具有高达 365 mAh g-1 的可逆充电比容量，循环 110 圈后的容量依然保持在 341 mAh g-1，容量保持率高达 86%，表现出较突出的循环稳定性；在大电流密度 1 A g-1 下进行充放电时，HBC-OMe 的充电比容量可以维持在 205 mAh g-1，容量保持率达 85%以上，结果表明该材料具有突出的循环稳定性和倍率性能；表现出的可逆容量衰减可能由于循环过程中颗粒表面 SEI 膜的过度累积造成储钠活性点减少和钠离子扩散受阻等原因。

Nowadays, with the shortage of fossil fuel resources, the arising of environmental problems and the growth of the electric vehicle market, people are increasingly demanding energy storage devices. Among the various secondary batteries, lithium-ion batteries (LIBs) have the advantages of high specific energy, high specific power, and fast response speed, but the scarcity of lithium resources cannot be solved. The chemical properties of sodium are similar to those of lithium, while its obvious advantages of abundant reserves, easy development and low cost over lithium making sodium ion batteries (SIBs) considered to be powerful alternatives to LIBs. However, the anode materials currently used as SIBs are still facing problems such as poor cycling stability and sluggish diffusion kinetic. It is imperative to develop new sodium storage electrode materials to meet the requirements of high-energy and high-power energy storage devices. Herein this paper, HBC and its derivative HBC-OMe were efficiently prepared by "bottom-up" organic synthesis methods. They all showed excellent cycle stability and rate performance when used as anode materials in SIBs. A variety of characterization methods were used to disclose the microstructure and crystal structure of the target product HBC, including X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM) and Raman, which displays sub-microsized aggregates with abundant pores and relatively large interlayers. Galvanicstatic charge and discharge (GCD) and Electrochemical impedance spectroscopy (EIS) tests were conducted at room temperature to evaluate the electrochemical performance of HBC. After long-term cycling as SIB anode material in half cell at the current density of 0.1 A g-1 for 400 cycles, HBC delivers a specific capacity up to 326mAh g-1, even higher than that of the initial cycle, demonstrating noteable cycling stability. The galvanicstatic step discharge-charge tests at various current rates were also performed for HBC. At a large current density of 5 A g-1, its reversible charge specific capacity can be maintained at 83 mAh g-1, and whencharged back at 0.1 A g-1, the charge capacity can recover 96% of that in the initial cycle, well indicative of impressive rate capability. The prominent sodium storage performance of HBC can be related to the large-interlayers and its relatively abundant porous structure between sub-microsized primary particles that can facilliate sodium diffusion and induce the formation of favorable solid-electrolyte-interface (SEI) film keeping structural integrity, respectively.In addition, we also prepared HBC-OMe and utilized it as anode material of sodium ion battery. At the current rate of 0.1 A g-1, HBC-OMe shows a reversible charge specific capacity of up to 365 mAh g-1, and the capacity delivered after 110 cycles of discharge-charge can still reach as high as 341 mAh g-1, with a capacity retention rate of 86%, showcasing decent cycling stability at the current rate of 1 A g-1, the reversible capacity remains at 205 mAh g-1 with a capacity retention rate up to 85%, exhibiting noticeable rate performance. The degradation of reversible capacity can be ascribed to the overly accumulated gel polymer-like SEI film on the surface of HBC-OMe particles as reavealed by SEM, leading to the reduced sodioum storage sites and frustrated Na ion diffusion.

钠离子电池 负极材料 多环芳烃 多环芳烃衍生物 循环性能 倍率性能

sodium ion battery anode electrode polycyclic aromatic hydrocarbons polycyclic aromatic hydrocarbon derivative cycling performance rate performance

中文

联合培养

南方科技大学

代鑫鑫. 多环芳烃及其衍生物在二次电池负极材料中的电化学性能研究[D]. 深圳. 哈尔滨工业大学,2020.