层次化结构多孔碳材料制备及其电化学存储性能

发布时间：2018-05-29 12:50

本文选题：多孔碳材料 + 层次孔结构　；参考：《清华大学》2016年博士论文

【摘要】：多孔碳具有高比表面积,化学稳定性强,成本较低,因而是一种极具前景的电化学能源存储材料。近年来,其复杂的孔结构和表面性质、以及较差的导电性限制了其广泛使用。针对上述问题,本研究工作设计并制备了具有层次化结构的多孔碳材料,包括层次化的孔结构、层次化的表面元素组成以及层次化的晶体结构,来实现电化学能源存储过程中的高容量和高通量,并详细探究了层次化结构与电化学储能性能之间的联系。设计了层次化的孔结构。首先,采用低浓度水热法,以嵌段共聚物F127作为软模板合成了具有层次孔结构的多孔碳纳米球材料,结果表明其连通的层次孔结构和纳米尺寸有利于电极材料的快速充放电。其次,以上述多孔碳纳米球为原料,采用KOH化学活化的方法进一步增强其孔结构,在保持其层次化孔结构的同时,提高了其比表面积。获得的活化多孔碳纳米球材料表现出243 F g-1,198F cm-3的高容量,以及20 A g-1高电流密度下容量保持67%的优秀倍率性能。在层次化孔结构的基础上设计了层次化的表面特性。具体来说,本研究工作采用氨气处理的方法对层次孔结构的多孔碳材料进行表面改性,进行丰富的表面氮元素掺杂。首先,采用F127作为软模板,二维氧化石墨烯作为生长基底,合成了具有层次孔结构的碳纳米球/石墨烯复合材料,再通过后续氨气气氛下热处理进行氮元素表面掺杂,将此种材料用于超级电容器和锂离子混合电容器时表现出优异的高功率性能。在超级电容器应用中,在80Ag-1的超高电流密度下容量保持48%;在锂离子混合电容器应用中,其功率密度可达336k Wkg-1。其次,以柠檬酸镁为硬模板,通过柠檬酸镁热解制备出具有发达层次孔结构的多孔碳材料,并通过后期氨气处理进行表面氮元素掺杂,所制备的氮掺杂层次孔结构多孔碳在锂硫电池应用中可实现超高的载硫量,高容量和高倍率,在超级电容器和锂离子混合电容器中也表现出高容量、高倍率的优秀性能;也通过柠檬酸镁/柠檬酸钾混合热解结合后续氨气气氛热处理的工艺制备出氮掺杂层次孔碳纳米片材料,将其用于超级电容器和锂硫电池时均可表现出优秀的倍率性能。最后,进行了层次化晶体结构的设计。本研究工作采用钴源作为石墨化催化剂,采用含氮有机物作为碳源前驱体实现氮元素掺杂,采用锌源作为硬模板制造层次化孔结构。将同时具有层次化孔结构、表面组成以及晶体结构的该多孔碳材料应用于锂硫电池,可表现出高容量和优异的倍率性能。
[Abstract]:Porous carbon has high specific surface area, strong chemical stability and low cost. Therefore, it is a promising electrochemical energy storage material. In recent years, its complex pore structure, surface properties and poor conductivity limit its extensive use. Carbon materials, including hierarchical pore structure, hierarchical surface element composition and hierarchical crystal structure, are used to achieve high capacity and high throughput in electrochemical energy storage. The relationship between hierarchical structure and electrochemical energy storage is explored in detail. A hierarchical pore structure is designed. First, low concentration hydrothermal method is used. The porous carbon nanospheres with layered pore structure are synthesized with block copolymer F127 as a soft template. The results show that the connected layered pore structure and nano size are beneficial to the rapid charge discharge of the electrode materials. Secondly, the porous carbon nanospheres are used as raw materials to further enhance the pore structure of the porous carbon nanospheres by KOH chemical activation. At the same time, the specific surface area was improved with its hierarchical structure. The activated porous carbon nanospheres showed high capacity of 243 F g-1198F cm-3, and the excellent multiplying property of 67% under the high current density of 20 A g-1. The hierarchical surface characteristics were designed on the basis of the hierarchical pore structure. The porous carbon materials with layered pore structure were modified by ammonia treatment and doped with rich surface nitrogen elements. First, F127 was used as a soft template and two dimensional graphene oxide was used as the growth substrate. The processing carries on the surface doping of nitrogen elements and exhibits excellent high power performance when used in supercapacitors and lithium ion hybrid capacitors. In supercapacitor applications, the capacity of the 80Ag-1 is 48% at ultra high current density; in the application of lithium ion hybrid capacitors, the power density is up to 336k Wkg-1. next, and citric acid is used. Magnesium is a hard template, and the porous carbon materials with advanced pore structure are prepared by the pyrolysis of magnesium citrate, and the surface nitrogen elements are doped through the later ammonia treatment. The prepared porous carbon with nitrogen doped layered pore structure can achieve super high sulfur load, high capacity and high ratio in the application of lithium sulfur batteries, in supercapacitor and lithium ion. The hybrid capacitor also shows excellent performance of high capacity and high ratio, and the nitrogen doped layered porous carbon nanoscale materials are prepared by the combined pyrolysis of magnesium citrate / potassium citrate combined with the subsequent ammonia atmosphere heat treatment, which can show excellent multiplier performance when they are used in supercapacitors and lithium sulfur batteries. Finally, it has been carried out. The design of hierarchical crystal structure. This study uses cobalt source as a graphitization catalyst. Nitrogen containing organic compounds are used as precursors of carbon source. The zinc source is used as a hard template to produce hierarchical pore structure. The porous carbon material with layered pore structure and the surface composition and crystal structure are applied to lithium sulfur. The battery can exhibit high capacity and excellent rate performance.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ127.11;TB383.4

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