多孔炭超级电容器电极材料的制备及倍率性能研究

发布时间：2018-06-13 10:38

本文选题：多孔炭 + 碳复合材料　；参考：《大连理工大学》2014年博士论文

【摘要】：超级电容器是人们广泛关注的一种新型的储能器件,具有功率密度高、循环寿命长等特点。多孔炭是目前广为使用的一种超级电容器电极材料,其微观形貌、比表面积、孔隙结构、导电性以及表面化学性质等均对电化学性能有着重要的影响。目前多孔炭电极材料除了能量密度较低之外,还因其结构特点存在倍率性能较差的缺点,进而限制了材料的高功率特性。本文旨在通过改善或者优化材料的孔隙结构、导电性和微观形貌,制备具有高倍率性能的多孔炭电极材料。以非离子表面活性剂P123为软模板,果糖为碳源,磷酸为磷源,耦合水热及热处理技术制备了具备多级孔结构的磷修饰碳纳米管／碳复合材料。适量的碳纳米管有利于增加复合材料的介孔和大孔孔容,并提高复合材料的导电性。与不含碳纳米管的材料相比,复合材料在10Ag-1的电流密度下电容保持率从6%提高到了78%。含磷官能团可使复合材料的操作电压提高至1.2V,并在该电压下保持优异的循环稳定性。以氧化石墨烯(GO)辅助氨基葡萄糖水热反应制备了高氮含量(10wt.%)的石墨烯／水热碳复合材料；GO可诱导氨基葡萄糖的水热中间物在其表面聚集而倾向形成片状结构。适量的石墨烯有利于水热碳复合材料的KOH活化过程,使产物具有更高的比表面积、微孔和介孔孔容,导电性也有3个数量级的显著提高。与不含石墨烯的材料相比,复合材料具有更高的比电容值(300F g-1)以及更好的倍率性能,在8Ag-1的电流密度下电容保持率由36%提高到了76%。以多巴胺为碳源,利用其在碱性有氧环境下的自聚特性,在纳米碳酸钙表面聚合了超薄聚多巴胺层。经热处理聚多巴胺层可转变为超薄碳层,同时纳米碳酸钙分解产生的二氧化碳可原位活化碳层引入微孔,除去模板后可得到类石墨烯结构的二维超薄多孔碳纳米片。电化学测试结果表明超薄多孔碳纳米片具有优异的倍率性能,在高达100Ag-1的电流密度下具有71%的电容保持率。以具有层状纳米空间的蒙脱土为限域模板,明胶和多巴胺为代表碳源,利用二者之间的插层反应构建了制备二维碳纳米片的通用方法,对碳纳米片进一步KOH活化处理可得多孔碳纳米片电极材料。基于明胶的多孔碳纳米片在高达100Ag-1的电流密度下比电容可达246Fg-1,电容保持率与明胶直接预炭化活化的产物相比由44%提高到82%。两电极体系下明胶基多孔碳纳米片在水系和有机系电解液中也均具有优异的倍率性能,在40Ag-1的电流密度下电容保持率分别可达83和81%。
[Abstract]:Supercapacitor is a new type of energy storage device, which has high power density and long cycle life. Porous carbon is a widely used electrode material for supercapacitors. Its micro-morphology, specific surface area, pore structure, conductivity and surface chemical properties all have important effects on electrochemical properties. In addition to the low energy density, the porous carbon electrode materials have the disadvantage of poor rate performance due to their structural characteristics, which limits the high power characteristics of the materials. The aim of this paper is to prepare porous carbon electrode materials with high rate properties by improving or optimizing the pore structure, electrical conductivity and micromorphology of the materials. Using Nonionic surfactant P123 as soft template, fructose as carbon source and phosphoric acid as phosphorus source, phosphorous modified carbon nanotubes / carbon composites with multilevel pore structure were prepared by coupled hydrothermal and heat treatment techniques. The proper amount of carbon nanotubes can increase the mesoporous and large pore volume of the composites and improve the conductivity of the composites. Compared with the materials without carbon nanotubes, the capacitance retention rate of the composites increased from 6% to 78% at the current density of 10Ag-1. Phosphorus-containing functional groups can increase the operating voltage of the composite to 1.2 V and maintain excellent cyclic stability at this voltage. A graphene / hydrothermal carbon composite with high nitrogen content (10 wt.) was prepared by hydrothermal reaction of glucosamine with graphene oxide (GOO), which can induce the hydrothermal intermediates of glucosamine to aggregate on its surface and tend to form a flake structure. Proper amount of graphene is propitious to the Koh activation process of hydrothermal carbon composites, which makes the products have higher specific surface area, micropore and mesoporous volume, and the electrical conductivity is improved by three orders of magnitude. Compared with the materials without graphene, the composite has higher specific capacitance value (300F g-1) and better rate performance. At the current density of 8Ag-1, the capacitance retention rate is increased from 36% to 76%. Using dopamine as carbon source, ultrathin polydopamine layer was polymerized on the surface of nanometer calcium carbonate by using its self-polymerization property in alkaline aerobic environment. After heat treatment, the polydopamine layer can be transformed into ultrathin carbon layer, and the carbon dioxide generated by the decomposition of nano-calcium carbonate can be activated in situ and introduced into micropores. After removing the template, two-dimensional ultrathin porous carbon nanochips with graphene like structure can be obtained. The electrochemical test results show that ultrathin porous carbon nanochips have excellent rate performance and have a capacitance retention rate of 71% at current density up to 100Ag-1. Using montmorillonite with layered nanospace as the limiting template and gelatin and dopamine as the representative carbon source, a general method for preparing two-dimensional carbon nanochips was constructed by intercalation reaction between them. Porous carbon nanochip electrode materials can be obtained by further Koh activation treatment of carbon nanochips. The specific capacitance of porous carbon nanoparticles based on gelatin can reach 246Fg-1 at current density up to 100Ag-1, and the capacitance retention rate is increased from 44% to 82% compared with the products directly precarbonated by gelatin. In the two-electrode system, gelatine-based porous carbon nanochips also have excellent rate performance in aqueous and organic electrolyte systems, and the capacitance retention rates can reach 83 and 81 at the current density of 40Ag-1, respectively.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TQ127.11;TM53

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