碳基复合电极材料的制备及其在超级电容器中的应用研究

发布时间：2018-04-29 00:29

本文选题：超级电容器 + 氮掺杂多孔炭　；参考：《安徽大学》2017年硕士论文

【摘要】：超级电容器,作为一种新型的电能存储器件,具有高功率密度、优异的稳定性、快速充放电功能以及环境友好等诸多优点,在电子、通信、交通、电力、工业节能、国防等许多领域具有重要的应用价值和巨大的市场潜力。电极材料是超级电容器的关键组成部分,常见的超级电容器电极材料包括碳材料、过渡金属氧化物和导电聚合物等。碳材料主要呈现双电层电容特性,具有优异的充放电循环稳定性,符合实际应用中对器件寿命的高要求,但是比电容相对较低。过渡金属氧化物和导电聚合物主要呈现赝电容特性,依赖可逆的化学吸附/脱附或氧化还原反应来储存电荷,虽然具有较高的比电容,但是电容循环稳定性较差。这些电极材料既有各自的优势,又有其不足。因此,对电极材料的研究并非仅限于单一组分材料,复合材料往往可以呈现出更加出色的电化学性能。碳基复合电极材料因其原料丰富、价格低廉、制备工艺简单且性能优异而倍受关注。本论文对碳基复合电极材料的制备、电化学性能及其在超级电容器中的应用进行了研究,主要研究内容如下:一、氮掺杂多孔炭的制备及其电容性能研究以天然产物为碳源,三聚氰胺为氮源,经碳化和氢氧化钾(KOH)高温活化后得到氮掺杂多孔炭(NPC)。在800℃下活化所得的NPC-800呈现多孔状的微观形貌,氮元素含量达到6.45 wt%,主要以吡啶氮和吡咯氮的形式存在。将NPC作为活性材料制备成电极并组装成对称型超级电容器。在两电极体系下,以6 mol L-1 KOH为电解液,通过恒电流充放电(GCD)和循环伏安(CV)测试表明:电流密度为0.1 Ag-1时,NPC-800所组装的超级电容器的比电容值达到145 F g-1,而且当功率密度为50 W kg-1时,能量密度可达到20 Wh kg-1。经过1000次循环充放电后,其比电容仍然能保持96.9%,库仑效率稳定在99%,以上结果表明NPC具有优良的电容特性和循环稳定性,适用于超级电容器电极材料。二、氧化石墨烯/聚吡咯二元复合材料的合成及其电容性能研究采用改进的Hummers法制得氧化石墨烯(GO),再采用原位聚合法合成氧化石墨烯/聚吡咯(GO/PPy)二元复合材料。扫描电子显微镜(SEM)表征可知该二元复合材料呈现褶皱的纳米片层形貌,这是由于PPy通过π-π堆叠、氢键和静电等相互作用从而在GO表面形成一层致密的覆盖层。在三电极系统中进行GCD和CV测试,结果表明在0.5Ag-1的电流密度下,GO/PPy的比电容值达到468Fg-1,高于单一 PPy电极的比电容值(267Fg-1)。而且,由于GO与PPy之间的协同效应,GO/PPy的倍率性能和循环稳定性也都得到了显著的提升。由此可见,PPy与GO复合以后所得GO/PPy二元复合物的电容性能得到了增强。三、氧化石墨烯/碳量子点/聚吡咯三元复合材料的合成及其电容性能研究分别采用微波辅助热解法、水热法以及原位聚合法合成了碳量子点(CDs)、氧化石墨烯/碳量子点(GO/CDs)二元复合物和氧化石墨烯/碳量子点/聚吡咯(GO/CDs/PPy)三元复合物。通过在GO纳米片与PPy层之间引入CDs可以提升三元复合材料的电子传输并降低电极的内部电阻以及电荷传输电阻。此外,具有高比表面积的CDs可以增强GO、CDs以及PPy三者之间的界面性能从而增大三元复合材料的介电常数。在0.5 A g-1的电流密度下,GO/CDs/PPy呈现出576 Fg-1的比电容,将其组装成对称型超级电容器,在250Wkg-1的功率密度下可获得的最大能量密度为30.1 Wh kg-1。更重要的是,三元复合物经过5000次充放电后仍具有较高的比电容,表现出优异的循环稳定性。为了评价电极材料的实际应用价值,我们将5个超级电容器串联成一个简易模组,发现仅需充电17秒就可以将59个发光二极管点亮超过1分钟。上述结果表明,CDs在提升GO/CDs/PPy三元复合材料的电容性能过程中起到了重要的作用,所构筑的双电层电容/赝电容混合超级电容器具有高的能量密度和优异的循环稳定性,从而具有潜在的市场应用前景。
[Abstract]:Supercapacitor, as a new type of electric energy storage device, has many advantages, such as high power density, excellent stability, fast charging and discharging function and environment friendly. It has important value and great market potential in many fields, such as electronic, communication, traffic, electric power, industrial energy saving, national defense and many other fields. Electrode material is a supercapacitor. The common supercapacitor electrode materials include carbon materials, transition metal oxides and conductive polymers. Carbon materials mainly exhibit double layer capacitance characteristics, and have excellent charge discharge cycle stability. It is in line with the high requirement for the life of the device in practical applications, but the specific capacitance is relatively low. And the conductive polymer mainly presents pseudo capacitance, depends on reversible chemical adsorption / desorption or redox reaction to store charge. Although it has a higher specific capacitance, the stability of the capacitance cycle is poor. These electrode materials have their own advantages and disadvantages. Therefore, the study of electrode materials is not limited to single component. Composite materials often show excellent electrochemical properties. Carbon based composite electrode materials have attracted much attention because of their rich raw materials, low price, simple preparation and excellent performance. This paper has studied the preparation, electrochemical properties and applications of carbon based composite electrode materials in super capacitor. The contents are as follows: 1. Study on the preparation and capacitive performance of nitrogen doped porous carbon with natural products as carbon source, melamine as nitrogen source, nitrogen doped porous carbon (NPC) after carbonization and potassium hydroxide (KOH) activation at high temperature. The activation of NPC-800 at 800 centigrade shows a multi pore morphology, and the content of nitrogen element reaches 6.45 wt%, mainly with pyridine. In the form of nitrogen and pyrrole nitrogen, the NPC was prepared as the active material and assembled into a symmetrical supercapacitor. Under the two electrode system, 6 mol L-1 KOH was used as the electrolyte, and the constant current charge discharge (GCD) and cyclic voltammetry (CV) test showed that the specific capacitance of the supercapacitor assembled by NPC-800 was reached when the current density was 0.1 Ag-1. To 145 F g-1, and when the power density is 50 W kg-1, the energy density can reach 20 Wh kg-1. after 1000 cycles charge and discharge, the specific capacitance remains 96.9% and the coulomb efficiency is stable at 99%. The above results show that NPC has excellent capacitance and cyclic stability. It is suitable for super capacitor electrode material. Two, graphene oxide / poly (graphite oxide). Synthesis and capacitive properties of pyrrole two element composite materials, graphene oxide (GO) was obtained by improved Hummers method, and two element composites of graphene oxide / polypyrrole (GO/PPy) were synthesized by in-situ polymerization. The scanning electron microscope (SEM) was used to characterize the nanoscale lamellar morphology of the two element composite material, which was due to PPy By pion pion stacking, hydrogen bonding and electrostatic interaction, a dense layer of cover was formed on the GO surface. GCD and CV tests in the three electrode system showed that the specific capacitance value of GO/PPy reached 468Fg-1 at the current density of 0.5Ag-1, higher than the specific capacitance value (267Fg-1) of the single PPy electrode. Moreover, the synergy between GO and PPy. The multiplier and cyclic stability of GO/PPy have been greatly improved. Thus, the capacitive performance of the GO/PPy two composite obtained by PPy and GO is enhanced. Three, the synthesis and capacitance of the graphene oxide / carbon quantum dots / polypyrrole three composite materials and the study of the capacitance properties of the composites are used respectively by the microwave assisted pyrolysis method. Carbon quantum dots (CDs), graphene oxide / carbon quantum dots (GO/CDs) two elements and three elements of graphene oxide / carbon quantum dots / polypyrrole (GO/CDs/PPy) are synthesized by thermal method and in situ polymerization. By introducing CDs between GO nanoscale and PPy layer, the electronic transmission of three element composite materials can be enhanced and the internal resistance of the electrode is reduced. In addition, the CDs with high specific surface area can enhance the interface property between the GO, CDs and PPy three, thereby increasing the dielectric constant of the three element composite. Under the current density of 0.5 A g-1, GO/CDs/PPy presents a specific capacitance of 576 Fg-1, which is assembled into a symmetric supercapacitor and can be obtained at the power density of 250Wkg-1. The maximum energy density is 30.1 Wh kg-1.. It is more important that the three element composite has a high specific capacitance after 5000 charge discharge, and shows excellent cyclic stability. In order to evaluate the practical application value of the electrode material, we series the 5 supercapacitors into a simple module, and it is found that only 59 can be charged for 17 seconds. The results show that CDs plays an important role in improving the capacitive performance of the GO/CDs/PPy three element composite. The constructed double layer capacitance / pseudo capacitor hybrid supercapacitor has high energy density and excellent cyclic stability, which has potential market prospects.

【学位授予单位】：安徽大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33;TM53

【参考文献】