氮掺杂多孔碳材料的制备及其电化学性能研究

发布时间：2018-04-10 07:08

本文选题：超级电容器　切入点：氮掺杂　出处：《扬州大学》2017年硕士论文

【摘要】：碳材料由于其来源丰富、导电性好、比表面积大且稳定性好,成为超级电容器最重要的电极材料。但其主要是通过双电层电容进行储能,能量密度较小。因此,如何提高电极材料的能量密度成为当前学术界关注的研究热点。根据能量密度计算公式知:E=0.5CV2,可以通过增大电压窗口或比电容来提高材料的能量密度。本文以明胶为碳源,分别通过尿素作为氮源对其氮掺杂改性,SiO_2作为模板增加比表面积,然后进一步负载2,5-二甲氧基-1,4-苯醌(DMQ)制备复合材料增加比电容。通过透射电镜(TEM)、扫描电镜(SEM)、X-射线衍射(XRD)以及拉曼光谱(Raman)等手段,对材料的形貌和结构等情况进行表征。采用多种电化学测试手段研究祠料的电化学性能以及循环稳定性。主要研究工作包括以下几个方面:(1)以明胶为碳源、尿素为氮源和模板,通过“原位”掺氮法合成氮掺杂介孔碳纳米纤维(N-m-CNFs)。研究了尿素的模板作用、掺入量以及煅烧温度对材料形貌、结构和电化学性能的影响。利用三电极体系,1MH2SO4作为电解液,测试不同氮掺杂量及碳化温度下碳纤维的电化学性能。结果表明,尿素掺入后,碳材料呈纤维状,氮含量高达14.632 wt%。在1Ag~(-1)的电流密度下,碳纤维的比电容值可达到230.9Fg~(-1),远大于不掺氮的碳材料(86.9Fg~(-1)),且具有较好的循环稳定性。(2)以明胶为碳源和氮源、SiO_2为模板,通过模板法得到孔径均一的氮掺杂多孔碳片层材料(N-p-CSs)。通过加入不同粒径SiO_2,调控制备不同孔径和比表面积的多孔碳片层材料,研究不同煅烧温度对所合成碳材料形貌、结构以及电化学性能的影响。结果表明,相对于无孔碳材料,不同粒径SiO_2所制备的碳材料比电容明显增大。其中,20nmSiO_2作为模板制备得到的碳材料,比电容值在电流密度为1 A g~(-1)时达到252.3 F g~(-1)。(3)以上述制备的多孔碳片层材料为基材,利用水热法在碳材料表面负载DMQ,制备DMQ@N-p-CSs复合材料。探讨了 DMQ负载量对所合成碳材料形貌、结构的影响,并分别测试了不同复合材料的电化学性能。实验表明,当DMQ与N-p-CSs质量比为1:1制备得到的复合材料具有较好的循环性能和较高的比电容。在电流密度为1 Ag~(-1)时,比电容可达到356.4 F g-2,经过10000次循环之后保持98.6%的初始比电容。
[Abstract]:Carbon is the most important electrode material for supercapacitors due to its rich source, good conductivity, large specific surface area and good stability.However, the energy storage is mainly by double layer capacitance, and the energy density is small.Therefore, how to improve the energy density of electrode materials has become the focus of academic research.According to the calculation formula of energy density, we know that the energy density of the material can be increased by increasing the voltage window or specific capacitance.In this paper, using gelatin as carbon source and urea as nitrogen source to increase the specific surface area of nitrogen-doped modified SiO-2 as template, then the composite was prepared by further loading 2o 5-dimethoxy-4-benzoquinone (DMQ) to increase specific capacitance.The morphology and structure of the materials were characterized by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy (Raman).The electrochemical performance and cyclic stability of ancestral materials were studied by various electrochemical methods.The main research work includes the following aspects: (1) N-doped mesoporous carbon nanofibers N-m-CNFsO were synthesized by "in-situ" nitrogen-doped method, using gelatin as carbon source and urea as nitrogen source and template.The effects of the template, the dosage of urea and the calcination temperature on the morphology, structure and electrochemical properties of urea were studied.The electrochemical properties of carbon fibers with different nitrogen doping amount and carbonization temperature were measured by using the three-electrode system of 1MH _ 2SO _ 4 as electrolyte.The results showed that the carbon material was fibrous and the nitrogen content was as high as 14.632 wts after the addition of urea.The specific capacitance value of carbon fiber can reach 230.9 FG ~ (-1) at current density, which is much larger than that of carbon material without nitrogen (86.9 FG ~ (-1)), and has good cycling stability. 2) gelatin as carbon source and nitrogen source SiO2 as template.N-p-CSsN doped porous carbon laminates with uniform pore size were obtained by template method.Porous carbon lamellar materials with different pore size and specific surface area were prepared by adding SiO-2 with different particle sizes. The effects of calcination temperature on the morphology, structure and electrochemical properties of the synthesized carbon materials were studied.The results show that the specific capacitance of carbon materials prepared with different particle sizes of SiO_2 is significantly larger than that of non-porous carbon materials.The DMQ@N-p-CSs composites were prepared by hydrothermal method on the surface of carbon materials prepared by using SiO-2 as template, and the specific capacitance reached 252.3 F g / g ~ (-1) when the current density was 1 A / g ~ (-1)). The porous carbon lamellar material was used as the base material.The effects of DMQ loading on the morphology and structure of the synthesized carbon materials were investigated, and the electrochemical properties of different composites were tested.The experimental results show that the composites prepared at 1:1 mass ratio of DMQ to N-p-CSs have better cycling performance and higher specific capacitance.The specific capacitance can reach 356.4 F g ~ (-2) when the current density is 1 Agg ~ (-1), and the initial capacitance is 98.6% after 10000 cycles.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TB383.4

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