多孔炭及其复合材料的制备与电化学性能研究

发布时间：2018-03-07 06:34

本文选题：多孔炭　切入点：多孔炭/碳纳米管　出处：《新疆大学》2016年硕士论文　论文类型：学位论文

【摘要】：当今化石能源的过度消耗促使人们把目光转向了清洁能源开发,以缓解化石能源危机。能量存储和转换器件是能否高效利用清洁能源的关键。炭材料在清洁和可持续能源技术中起着非常重要的作用,多孔炭作为炭材料中重要的一员,拥有较大的比表面积、高导电率、孔结构可调控、来源广泛、价廉易得、物理和化学性质稳定等优点,受到了国内外科研者的广泛关注。本论文将多孔炭及其与碳纳米管的复合物作为电化学电容器和锂离子电池的活性物质。运用扫描电镜(SEM)、透射电镜(TEM)、比表面积测试(BET)、X-射线衍射(XRD)、X射线光电子能谱(XPS)和红外光谱(IR)等手段对多孔炭及其复合物的组成、结构、形貌进行了表征,运用交流阻抗(EIS)、循环伏安法(CV)和恒流充放电(CD)等技术对多孔炭及其复合物进行了电化学性能评价。系统地研究了多孔炭及其复合物的制备方法、形貌、结构及其电化学性能,且达到了预期的研究目的。前言部分简单介绍了炭材料的分类及炭材料的优点,着重介绍了多孔炭的制备方法,多孔炭的改性方法以及多孔炭在电化学方面的主要应用。首先,以冷冻干燥获得的多孔胡萝卜为碳源,经过600 oC氮气氛围下炭化和KOH活化,获得了多孔结构的炭材料。结果表明:通过活化处理,多孔炭的比表面积从7.0 m2 g-1大幅提高到147.2 m2 g-1。而且,活化后的多孔炭产生了414 F g-1的最大比电容,且电流增至4 Ag-1时的电容保持率为74.5%。而未活化的多孔炭最大电容为253 F g-1,电容保持率仅为45.1%。此外,活化后的多孔炭还具有优异的电化学稳定性。在5 A g-1电流下循环8000圈后,其电容保持率高达94%。活化后的多孔炭在电容性能方面的极大改善与其比表面积的大幅提高及介孔的增多有密切关系。其次,通过共热解廉价的三聚氰胺和聚乙二醇前驱体,然后刻蚀除去氧化镁这一简单有效的方法制备了交联网络结构的氮掺杂多孔炭材料。系统的研究了聚乙二醇-氧化镁-三聚氰胺的比例以及热解温度对多孔炭的形貌、结构和组成的影响。结果表明,多孔炭的电化学电容行为可以通过简单调整各组分的比例和热解温度进行调节。当聚乙二醇-氧化镁-三聚氰胺的比例为10:7:3,热解温度为700 oC时材料表现为交联的网络状结构,具有最高的比表面积370.8 m2 g-1和1.65 cm-3 g-1的总孔容,8.54 at.%的含氮量,以及保存完好的孔结构。这些优点有助于其在1 A-1的电流密度下获得485 F g-1的高比电容,同时具有良好的循环稳定性,在5 A g-1电流密度下经过8000循环后,材料的比电容并没有衰减。基于原料来源广泛,制备方法简单和电化学性能优异,这种具有分级结构孔道结构的氮掺杂网络状炭材料有望在实际中得到应用。最后,探索制备了多孔炭/碳纳米管复合材料。以上一章制备的多孔炭为基础通过在前驱体中添加不同比例的碳纳米管,经炭化-酸刻蚀氧化镁后成功制备出一系列多孔炭/碳纳米管复合材料。物性测试结果显示,多孔炭和碳纳米管之间形成了比较理想的复合结构,同时具有较大的比表面积,最高可以达到1015.2m2 g-1。电化学测试的结果表明,合适的碳纳米管添加量可以有效降低复合材料的传荷电阻(Rct)。碳纳米管的添加量为3 wt.%时,复合材料PC@3%CNT具有最低的传荷电阻(70.5Ω)和最高的比容量,在200 m A g-1的电流密度下,经过100圈循环后容量没有出现衰减,保持在714.5 m Ah g-1。因此,该复合物有望作为锂离子电池负极材料,也为其它的多孔炭/碳纳米管复合物的制备提供了新思路。
[Abstract]:The excessive consumption of fossil energy prompted people to turn to the development of clean energy, to alleviate the crisis. The fossil energy storage and energy converter is the key whether efficient use of clean energy. Carbon material plays a very important role in the clean and sustainable energy technology, porous carbon as an important member in carbon materials, have the large surface area, high conductivity, the pore structure can be regulated, wide source, cheap, has the advantages of stable physical and chemical properties, has attracted wide attention of domestic surgical research. This thesis will compound porous carbon and carbon nanotubes as an active material for electrochemical capacitor and lithium ion battery. By using scanning electron microscopy (SEM), transmission electron microscopy (TEM), n2adsorption (BET), X- ray diffraction (XRD), X ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) and other means of porous carbon and Its Composites Group A structure, morphology were characterized by AC impedance (EIS), cyclic voltammetry (CV) and galvanostatic charge discharge (CD) technology for the evaluation of electrochemical performance of porous carbon and its composites. The morphology of the preparation method, systematic study of porous carbon and its composite structure, and its electrochemical performance, and the purpose of the study is achieved. The introduction part introduces the classification and advantages of carbon materials, carbon materials, with emphasis on the preparation of porous carbon, the main application of modification methods of porous carbon and porous carbon in electrochemical aspects. First, to freeze dry porous carrots as the carbon source, through the 600 oC under nitrogen atmosphere carbonization and activation of KOH, the carbon material with porous structure. The result indicates that the activation of the porous carbon surface area from 7 m2 to 147.2 M2 g-1 significantly increased g-1. and porous carbon after activation produced 414 F G -1 the maximum specific capacitance, and the capacitance current to 4 Ag-1 when the maximum retention rate of capacitance of porous carbon was 74.5%. without activation of the 253 F g-1, capacitance retention rate is only 45.1%. in addition, porous carbon after activation also has excellent electrochemical stability. 8000 cycles at 5 A g-1 current, its capacitance keep the great improvement rate of 94%. after activation of the porous carbon in terms of performance and capacitance than the increase of surface area and mesopore more closely. Secondly, by CO pyrolysis of cheap melamine and polyethylene glycol precursor, and then etched Magnesium Oxide this simple and effective method of preparing nitrogen doped porous carbon materials the crosslinking network structure. Systematic Study on the morphology of polyethylene glycol - Magnesium Oxide - melamine and the ratio of pyrolysis temperature on porous carbon, influence of structure and composition. The results show that the porous carbon for electrochemical capacitor As can be adjusted by simply adjusting the proportion of each component and the pyrolysis temperature. When the PEG - Magnesium Oxide - Melamine ratio 10:7:3, pyrolysis temperature is 700 oC when the material behaves as the crosslinking network structure, compared with the total pore surface area of 370.8 M2 g-1 and 1.65 cm-3 g-1 is the highest, the nitrogen content of 8.54 at.% the well preserved pore structure. These advantages can get 485 F g-1 in the high capacitance current density at 1 A-1, and also has good cycle stability. After 8000 cycles at 5 A g-1 current density, material specific capacitance and no attenuation. Based on the wide sources of raw materials, preparation the preparation method is simple and has excellent electrochemical properties, the hierarchical structure of the pore structure of nitrogen doped carbon materials network is expected to be applied in practice. Finally, explore the porous carbon / carbon nanotube composite material was prepared. The above chapter system The preparation of porous carbon based by adding different proportion in the precursor of carbon nanotubes by carbonization and etching after Magnesium Oxide successfully prepared a series of porous carbon / carbon nanotube composite material. Test results show that the composite ideal structure formed between the porous carbon and carbon nanotubes, and high the specific surface area, the maximum can reach 1015.2m2 g-1. electrochemical test results show that the appropriate amount of carbon nanotubes can effectively reduce the charge transfer resistance of composite materials (Rct). The addition of carbon nanotubes is 3 wt.%, PC@3% composite, CNT has the lowest charge transfer resistance (70.5) and the highest specific capacity. At a current density of 200 m A g-1, after 100 cycles the capacity does not appear to decay, maintained at 714.5 m Ah g-1., therefore, the compound could be used as anode materials for lithium ion batteries, but also for other porous carbon / carbon nano The preparation of tube complex provides a new way of thinking.

【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ127.11;TB332

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