电纺多孔富氮碳纤维的制备及其电化学性能的研究

发布时间：2018-03-28 19:28

本文选题：超级电容器　切入点：静电纺丝　出处：《扬州大学》2016年硕士论文

【摘要】：超级电容器是一种介于传统电容器和电池之间的新型储能器件,具有电容量大、循环寿命长、充放电时间快、功率密度高和维护成本低等优点。随着社会的发展,超级电容器作为新型储能器由于其优越的性能受到研究者们越来越多的重视,在新能源汽车,国防航天、传感器等领域具有广阔的应用前景。电极材料是超级电容器的核心部分,是决定超级电容器性能的关键,因此,制备高性能的电极材料是超级电容器研究的重点。碳材料是目前应用最多的超级电容器电极材料,其具有比表面积大,孔结构可控,化学性质稳定等优点,另外碳材料来源广泛,生产成本低。静电纺丝提供了一种成本低廉、简便高效制备碳纤维及复合纤维的方法,且纤维直径可调。本文选用聚丙烯腈(PAN)作为纺丝前驱体,以三聚氰胺作为氮源,将三聚氰胺合成密胺树脂(MF)以溶解于纺丝液中,通过静电纺丝制备纤维原丝,再经过预氧化、碳化制备出富氮碳纤维,通过将富氮碳纤维活化,在纺丝前驱体中加入造孔剂等方法制备多孔富氮碳纤维,采用扫描电镜(SEM)、X射线衍射仪(XRD)、X光电子能谱(XPS)、N2吸脱附等测试方法对纤维的物理和化学性质进行了表征分析。将制得的碳纤维制成电极,采用循环伏安法和恒电流充放电法对碳纤维进行了电化学测试。其主要研究内容如下：通过静电纺丝制备出了不同MF掺杂量的纤维原丝,MF掺杂量依次为0%、25%、50%和75%,在250℃下预氧化,800℃碳化后制得了富氮碳纤维。表征结果表明：纺丝液中掺杂MF后依然可制得纤维,但直径有所变粗,碳化后纤维直径减小；碳纤维均为无定型石墨结构；碳纤维表面的氮元素含量随着MF掺杂量的增大而增大,当掺杂量为75%时,碳纤维表面的氮含量高达12.1%。电化学测试结果发现MF掺杂量为75%的碳纤维表现出最好的电化学性能：1A/g电流密度下比电容为144F僧,远高于未掺杂MF的纯PAN碳纤维；在10A/g电流密度下比电容为85F/g,与1A/g电流密度下相比保持了60%的比电容,具有良好的倍率性能。将制得的PAN和MF(75)/PAN富氮碳纤维浸泡在KOH溶液中,再在800℃C下活化30rmin以制取多孔富氮碳纤维。表征结果表明：活化后的碳纤维仍为无定型石墨结构,且石墨化程度有所降低。由于KOH的加入以及二次高温处理使得活化后碳纤维表面的氮元素含量下降,但氧元素含量略微增加。KOH活化后极大的提高了纤维的比表面积,其中活化后PAN碳纤维的比表面积从原来的6m2/g提高到了868m2/g,活化后MF/PAN碳纤维的比表面积从原来的58m2/g增大到了453m2/g,纤维中的微孔和中孔数量也大大增加。电化学测试结果表明活化后两纤维的电化学性能都优于活化前,其中由于含氮官能团和孔结构的协同作用,使得(A)MF/PAN碳纤维具有最出众的电化学性能,在1A/g电流密度下比电容高达255F/g,且在10A/g电流密度下比电容为209F/g,比电容保持率高达82%。任纺丝前驱体中加入聚乙二醇作为造孔剂,通过静电纺丝、预氧化、碳化得到多孔富氦碳纤维。表征结果表明：聚乙二醇的加入不会改变碳纤维表面的元素含量;聚乙二醇在高温下热解成气体小分子而起到造孔作用,使得到的碳纤维比表面积由原来的58m2/g增大到了209m2/g;电化学测试结果表明通过聚乙二酣造孔制得的多孔富碳氮碳纤维任1A/g电流密度下的比电容为280F/g,与通过KOH活化得到的纤维相比具有更好的电化学性能。
[Abstract]:The super capacitor is a new energy storagecomponent between conventional capacitors and batteries can have devices, large capacity, long cycle life, fast charge and discharge time, high power density and low maintenance costs. With the development of society, as a new type of super capacitor energy storage device due to its superior performance by researchers more and more attention in the new energy vehicles, aerospace and defense, has broad application prospects in areas such as sensors. The electrode material is the core part of the super capacitor, is the key to determine the performance of super capacitor, therefore, the preparation of high performance electrode material of super capacitor is the focus of research. The carbon material is used most of the super capacitor electrode material, which has a large surface area, controllable pore structure, has the advantages of stable chemical properties, in addition to carbon of wide material source, low production cost. The electrospinning provides a low cost The method is simple and efficient preparation of carbon fiber and composite fiber, and the fiber diameter is adjustable. The polyacrylonitrile (PAN) as a spinning precursor, using melamine as nitrogen source, the synthesis of melamine melamine resin (MF) to dissolve in the spinning solution, preparation of fibers by electrospinning, after pre oxidation carbide, prepared nitrogen rich carbon fiber, the nitrogen rich carbon fiber activation, adding pore forming agent and preparation method of porous carbon fiber spinning in a nitrogen rich precursor, using scanning electron microscopy (SEM), X ray diffraction (XRD), X ray photoelectron spectroscopy (XPS), N2 and physical absorption chemical desorption test method of fiber were characterized. The carbon fibers made of electrode by cyclic voltammetry and galvanostatic charge discharge method of electrochemical test of carbon fiber. The main research contents are as follows: through electrospinning prepared different doping amount of MF The fiber, the doping amount of MF was 0%, 25%, 50% and 75%, at a temperature below 250 DEG C after pre oxidation, 800 carbide prepared nitrogen rich carbon fiber. The characterization results showed that the spinning solution after MF doping can still obtain a fiber, but the diameter is thicker, carbonized fiber diameter decreases; the carbon fiber was amorphous graphite structure; the nitrogen content of the surface of the carbon fiber increases with the increase of MF doping amount, when the doping amount was 75%, the nitrogen content of carbon fiber surface is as high as 12.1%. electrochemical test results showed that MF doped with 75% carbon fiber showed the best electrochemical current density: 1A/g under the specific capacitance of 144F is much higher than that of pure PAN monk, not carbon fiber doped MF; 85F/g capacitance in the current density of 10A/g, and the current density of 1A/g compared to maintain a 60% specific capacitance, with good rate capability. PAN and MF will be prepared (75) nitrogen rich carbon fiber soaked in /PAN K In OH solution, and then at 800 DEG C under 30rmin to produce nitrogen rich porous activated carbon fiber. The results showed that: the carbon fiber after activation is amorphous graphite structure, and the degree of graphitization decreased. Due to the addition of KOH and two times of high temperature after activation treatment makes the nitrogen content of the carbon fiber surface decreased. But the oxygen content increased slightly after the activation of.KOH has greatly improved the specific surface area of the fiber, the activated carbon fiber PAN specific surface area from 6m2/g to 868m2/g, MF/PAN activated carbon fiber surface area increased from the original 58m2/g to 453m2/g, the number of micropores and mesopores in fiber also greatly increased. The electrochemical tests show that the electrochemical performance of activated two fibers are better than before activation, which due to the synergistic effects of nitrogen containing functional groups and pore structure, the (A) MF/PAN carbon fiber has the best electrochemical performance Can, in the current density of 1A/g specific capacitance as high as 255F/g, and in the current density of 10A/g 209F/g specific capacitance, the capacitance retention was as high as 82%. spinning precursor adding polyethylene glycol as pore through electrostatic spinning, preoxidation, carbonization to obtain porous helium rich carbon fiber. The results show that the characterization of polyethylene glycol the addition will not change the content of carbon fiber surface; polyethylene glycol under high temperature pyrolysis gas into small molecules and play the role of pore, the carbon fiber had higher surface area increases from original 58m2/g to 209m2/g; the electrochemical test results table of porous carbon and nitrogen rich carbon fiber by polyethylene two fast pore system the current density of 1A/g is lower than the capacitance of 280F/g, electrochemical and have better performance compared with the fiber obtained by KOH activation.

【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ340.64;TM53

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