基于有机钾盐前躯体制备功能化多孔碳基电极材料及电化学性能研究

发布时间：2018-02-02 16:21

本文关键词： 超级电容器碳基电极材料乙二胺四乙酸三钾盐(EDTA-3K) 自活化掺杂电化学性能　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着能源危机加剧和环境问题日益突出,迫切需要开发绿色环保、性能卓越的储能装置。超级电容器作为一种新型储能元件,具有能量密度和功率密度高、循环寿命长、环境友好等特性,是理想的储能系统,因此开发超级电容器具有重要的理论意义和应用价值。超级电容器性能的优劣主要取决于所用的电极材料。多孔碳及其复合材料,因其具有物化性质稳定、循环性能好、环保无污染等特点,被广泛用作超级电容器电极材料。如何简单可控地制备高性能多孔碳基电极材料仍然是当前面临的挑战之一。本论文围绕如何提高超级电容器电极材料的性能展开,提出利用富氮有机钾盐为碳源,一步自活化制备掺杂型多孔碳材料,同时与模板限域法、微波法、水热法等相结合,对其孔结构调控和复合改性,获得了一系列高比电容的新型多孔碳基电极材料。采用多种表征技术对形貌特征、孔隙结构、组成成分、结晶性等进行测试,利用循环伏安、恒电流充放电、交流阻抗等方法测试其电化学性能,筛选和构建高性能超级电容器用多孔碳基电极材料体系。主要研究工作如下:(1)以EDTA-3K为碳源,通过一步煅烧法,利用分子内含氮、氧以及羧酸钾,自活化原位掺杂制备了高比表面积氮氧双掺杂多级孔碳材料EPCs-T。探讨不同煅烧温度的影响,发现氮氧含量随温度升高而减少,孔体积和孔径随温度增加而增大,EPCs-800拥有最高比表面积,达到2787 m~2 g~(-1),同时,EPCs-800的比电容性能最好,电流密度为1 A g~(-1)时比电容为182.3 F g~(-1),在电流密度5 A g~(-1)下经过2000次循环之后比电容能够保持最初的95.2%,说明该超级电容器电极材料具有较好的充放电稳定性。(2)以EDTA-3K为碳源,SBA~(-1)5为硬模板,通过限域碳化制备掺杂型多级孔碳材料SEPCs-T。探讨煅烧温度对其孔隙结构、组成成分等理化性质及电容性能的影响。表征结果表明SEPCs-T呈现清晰海绵状结构,微孔比表面积随煅烧温度升高而减小,而孔体积和孔径尺寸随煅烧温度升高而增大,SEPCs-800比表面积最高(2578 m~2 g~(-1))。同条件下,SEPCsT的氧/氮含量与上章节制备的EPCs-T并没有明显差异。SEPCs-700的电化学性能最好,在电流密度为1 A g~(-1)时比电容为213.8 F g~(-1)。SEPCs-T含有大量介/大孔结构,提供有效的离子传输通道促进离子迁移和储存,有助于提升电极材料电化学性能,进而比电容值高于EPCs-T。(3)以EPCs-800为载体,采用恒温水浴和微波辐射法两种不同加热方式,通过尿素均匀沉淀法和低温氧化法相结合在EPCs-800表面生长双金属氧化物NiCo_2O_4纳米片,制备出EPCs-800/NiCo_2O_4复合电极材料,来增加赝电容,提高电化学性能。两种加热方式都可以使NiCo_2O_4成功地负载于EPCs-800多孔碳表面,但是其生长取向有所不同。传统水浴加热制备的NiCo_2O_4平行于碳表面方向上生长;而微波辐射法制备的NiCo_2O_4垂直于碳表面生长,且更加均匀、致密。电化学结果:电流密度为1 A g~(-1)时,EPCs-800/NiCo_2O_4~(-1)和EPCs-800/NiCo_2O_4-2电极材料的比电容值分别为207.6和434.8 F g~(-1),并且EPCs-800/NiCo_2O_4-2电极拥有更好的倍率性能、循环性能和更低的电阻。(4)以硝酸钴为金属源,尿素为碱源和氮源,EDTA-3K为碳、氮源及活化剂,同时掺入石墨烯纳米片,采用水热法、高温煅烧法和低温氧化法相结合,制备出四氧化三钴/石墨烯纳米片/碳三元多级结构复合电极材料(Co_3O_4/GNS/EPCs)。表征测试结果显示,石墨烯纳米片起到结构导向与模板调控作用,同时EDTA-3K又可以自活化和同步活化石墨烯,被插层的EDTA-3K源多孔碳与活化的石墨烯纳米片一起构成复合碳纳米片层结构,促使Co_3O_4纳米颗粒高度分散,避免了相互堆叠。此外,加入石墨烯很大程度地提升了复合材料导电性。电化学性能测试显示Co_3O_4/GNS/EPCs电极材料在电流密度为1 A g~(-1)时比电容达到772.4 F g~(-1),远高于纯碳材料EPCs-T,同时具有很好的倍率特性、循环性能以及低的阻抗。优良的电化学特性可能归因于活化的导电石墨烯层、多孔碳、Co_3O_4纳米颗粒以及氮氧元素掺杂四者之间协同作用的结果。
[Abstract]:With the aggravation of energy crisis and environmental problems have become increasingly prominent, urgent need for the development of green environmental protection, excellent performance of the super capacitor energy storage device. As a new type of energy storage device with energy density and high power density, long cycle life, environmental friendliness, is the ideal energy storage system, so the development of super capacitor with the important theoretical significance and application value. The merits of super capacitor performance mainly depends on the electrode materials used. Porous carbon and its composite materials, because of its stable physicochemical property, good cycle performance, no environmental pollution and other characteristics, are widely used as electrode material for supercapacitor. How simple and controllable preparation of carbon high performance porous electrode material is still one of the current challenges. This paper focuses on how to improve the performance of the super capacitor electrode material, the nitrogen rich organic potassium as a carbon source. Step self doped porous carbon materials and activation, confinement and template method, microwave method combined with hydrothermal method, the pore structure control and composite modification, obtain a series of high specific capacitance of porous carbon based electrode materials. Using a variety of characterization techniques on morphology, pore structure and composition to test the composition, crystallinity, by cyclic voltammetry, galvanostatic charge discharge and AC impedance method to test its electrochemical performance, selection and construction of high performance supercapacitors using porous carbon based electrode system. The main research work is as follows: (1) using EDTA-3K as carbon source, through one step sintering method, using molecular nitrogen, oxygen and potassium carboxylate, since activation in situ doping were prepared with high specific surface area for oxygen and nitrogen doped hierarchicalporous carbon material EPCs-T. to investigate the effects of different calcination temperature, found that the content of nitrogen and oxygen decreases as the temperature increases, the pore volume and pore size with temperature Increases, EPCs-800 has the highest surface area, up to 2787 m~2 g~ (-1), at the same time, EPCs-800 had better than capacitive performance, current density of 1 A g~ (-1) when the specific capacitance of 182.3 F g~ (-1), at a current density of 5 A g~ (-1) after 2000 cycle the capacitance can keep the original 95.2%, indicating that the electrode material of super capacitor charge and discharge with a good stability. (2) using EDTA-3K as carbon source, SBA~ (-1) 5 as hard templates were prepared by doped hierarchicalporous carbon materials SEPCs-T. study on the pore structure of the calcination temperature limit domain carbonization, influence of composition the physicochemical properties and capacitance performance. The characterization results show that SEPCs-T presents a clear spongy structure, micropore surface area with the calcination temperature increasing, the pore volume and pore size increased with the calcination temperature increasing, the specific surface area of the highest SEPCs-800 (2578 m~2 g~ (-1)). Under the same condition, the oxygen SEPCsT / The electrochemical performance and nitrogen content of the chapters prepared EPCs-T and no significant difference of the.SEPCs-700 best, at a current density of 1 A g~ (-1) when the specific capacitance of 213.8 F g~ (-1).SEPCs-T contains a large number of medium / large pore structure, provide ion transfer channels effectively promote ion transport and storage, help enhance the electrochemical performance of electrode materials, and the specific capacitance is higher than that of EPCs-T. (3) with EPCs-800 as the carrier, with constant temperature water bath and microwave radiation by two different heating methods, the growth of double metal oxide NiCo_2O_4 nano film on the surface of EPCs-800 by urea homogeneous precipitation method and low-temperature oxidation method, preparation of EPCs-800/NiCo_2O_4 composite electrode materials to increase pseudocapacitive, improve the electrochemical performance. Two kinds of heating methods can make NiCo_2O_4 successfully loaded on EPCs-800 porous carbon surface, but its growth orientation is different. The traditional water bath heating preparation The growth of NiCo_2O_4 is parallel to the direction of carbon on the surface; and the microwave radiation preparation of NiCo_2O_4 perpendicular to the surface of carbon growth, and more uniform and compact. The electrochemical results: current density of 1 A g~ (-1), EPCs-800/NiCo_2O_4~ (-1) and EPCs-800/NiCo_2O_4-2 electrode specific capacitance values were 207.6 and 434.8 F g~ (-1), and rate performance of EPCs-800/NiCo_2O_4-2 electrode has better performance and lower resistance, cycle. (4) using cobalt nitrate as metal source, alkali source and urea as nitrogen source, EDTA-3K carbon, nitrogen source and activator, and the incorporation of graphene nanosheets by hydrothermal method, the combination of high temperature calcination method and low temperature oxidation, prepared four oxidation three cobalt / graphene nanosheets / carbon composite electrode material three yuan multistage structure (Co_3O_4/GNS/EPCs) characterization. The testing results show that the graphene nanosheets to guide and regulate the template structure, and at the same time EDTA-3K Self activation and synchronous live graphene, EDTA-3K source porous carbon intercalation and graphene nanosheets activated carbon nano composite composed of lamellar structure, the highly dispersed Co_3O_4 nanoparticles, avoid overlapping. In addition, addition of graphene greatly improves the conductivity of the composite material. The electrochemical performance of test shows that the electrode materials of Co_3O_4/GNS/EPCs at a current density of 1 A g~ (-1) is a specific capacitance of 772.4 F g~ (-1), much higher than that of pure carbon material EPCs-T, and has very good rate performance, cycle performance and low electrical impedance. Excellent chemical properties may be attributed to the conductive graphene layer, porous activated carbon, nitrogen and oxygen between Co_3O_4 nanoparticles and doping the synergy of the four results.

【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332;TM53

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