【作者】 王芳平；

【导师】 王红强； 钟新仙； 李庆余；

【作者基本信息】 广西师范大学 ， 应用化学， 2010， 硕士

【摘要】 伴随人口的急剧增长和社会经济的快速发展,资源和能源日渐短缺,生态环境日益恶化,人类将更加依赖洁净和可再生的新能源。超级电容器(supercapacitor)也叫做电化学电容器(electrochemical capacitor),是一种介于传统电容器和电池之间的新型储能元件,它既具有传统电容器放电功率高,又具有电池电荷储存能力大的特点。与传统电容器相比,超级电容器具有更大的容量以及更高的能量密度,其容量可达法拉(F)甚至数千法拉,而传统的电容器只有微法(μF)级;与电池相比,超级电容器具有更高的功率密度和更长的循环寿命,可实现快速充放电。电极材料是影响超级电容器性能与成本的关键因素之一。目前,超级电容器的电极材料主要有碳材料、金属氧化物和导电聚合物三种。在众多导电聚合物中,聚苯胺(polyaniline, PANI)由于具有原料易得、合成简便、成本低廉,并且具有良好的化学稳定性、导电性和高的赝电容储能等特性,使其成为了超级电容器电极材料的研究热点。本文采用化学氧化聚合法,以二氧化锰(MnO2)作为氧化剂,在室温条件下制备了电化学性能优异的超级电容器用PANI材料、PANI-碳纳米管(CNTs)和PANI-Co3O4复合材料。此外,还采用界面聚合法制备PANI材料,研究不同浓度的HCOOH做掺杂剂时对PANI材料形貌及电化学性能的影响。研究了所得材料电极在酸性介质中的电化学电容特性。本文主要研究内容如下：(1)以MnO2、过硫酸铵(APS)作为氧化剂,采用化学氧化聚合法在室温下制备得到PANI,并采用扫描电子显微镜(SEM),傅立叶变换红外光谱(FTIR)以及X-射线衍射(XRD)对其结构和形貌进行了表征。用循环伏安法、电化学阻抗和恒电流充放电技术测试了以其作为电极的超级电容器的电化学性能。结果表明,以MnO2为氧化剂制备的PANI(简称为M-PANI)在电流密度为5 mA/cm2下的单电极比容量达260 F／g,500次循环后容量仍稳定在188 F／g,比电容保持率为72.3%。比以APS作为氧化剂制备的PANI(简称为N-PANI)具有更高的比容量和更好的循环性能。(2)以MnO2作为氧化剂,采用化学氧化聚合法在室温下制备得到PANI-CNTs(简称为M-PC)纳米复合材料,并采用SEM、FTIR、XRD对PANI-CNTs复合材料的结构与性能进行了表征。用循环伏安法、恒电流充放电技术测试了以其作为电极的超级电容器的电化学性能。恒电流充放电实验结果表明,在不同电流密度恒流充放电时,M-PC纳米复合材料比容量随着电流密度的增大而降低；在电流密度为5 mA/cm2下单电极比容量达355F／g,500次循环后容量为306 F／g,比电容保持率为86.2%。M-PC较以APS为氧化剂制备的PANI-CNTs(简称为N-PC)具有更高的比容量和更好的循环性能。(3)以MnO2为氧化剂,采用化学氧化聚合法在室温下制备得到PANI-Co3O4复合材料,SEM、FTIR以及XRD技术对其进行结构、形貌表征。用循环伏安法和恒电流充放电技术测试了以其作为电极的超级电容器的电化学性能。结果表明,制备的PANI-Co3O4复合材料在电流密度为5 mA/cm2下的单电极比容量达287 F／g,500次循环后容量仍有271F／g,比电容保持率为94.4%。比M-PANI和Co3O4具有更好的循环性能和更高的比容量。(4)采用界面聚合法,以FeCl3作氧化剂,不同浓度的HCOOH做掺杂剂,在室温下制备了不同形貌PANI纳米材料,采用SEM、XRD对PANI的结构和形貌进行了表征。以PANI为活性物质制备电极,1 mol/L H2SO4水溶液为电解液组装超级电容器,通过循环伏安法和恒电流充放电技术研究了其电化学性能。结果表明,通过控制HCOOH的浓度可以得到不同形貌的HCOOH掺杂的PANI纳米材料；其中纤维状的PANI作为电极材料的超级电容器在15 mA/cm2放电电流下,其比电容为292 F/g,500次循环后容量仍维持在201 F/g,比电容保持率为68.8%。更多还原

【Abstract】 With the rapid growth of population and rapid development of socio-economic, resources and energy are hard up day by day, the environment is deteriorating, and human beings will be more dependent on the new clean and renewable energy. Supercapacitor (also known as electrochemical capacitors) is a new type electrochemical energy storage device between the traditional dielectric capacitor and the battery. Compared with the conventional capacitor, supercapacitor has a larger capacity and higher energy density, its capacity can be Farah (F) or even thousands of Farah, but the capacity of the traditional capacitor is only microfarads (μF). Compared with the battery, supercapacitor has higher power density and longer cycle life, can realize high-current charging and discharging. Electrode material is one of the important factors in affecting the performance and cost of supercapacitor. Electrode material mainly includes carbon material, metal oxide and conducting polymer. Among the conductive polymer, polyaniline (PANI) is a focus due to raw material readily available, easy synthesis, low cost, good chemical stability and electrical conductivity, high pseudo-capacitance energy storage and other characteristics.In this dissertation, PANI, PANI-CNTs and PANI-Co3O4 composite were prepared by chemical in-situ polymerization using manganese dioxide (MnO2) as the oxidant. In addition, PANI nano-materils with different morphology have been synthesized successfully by interfacial polymerization with FeCl3 as oxidant and different concentrations HCOOH as dopant. The electrochemical performances of the PANI, PANI-CNTs and PANI-Co3O4 in acidic media have been studied. The main points of this dissertion are summarized as follows:(1) PANI was prepared by chemical in-situ polymerization at ambient temperature, using MnO2 or ammonium persulphate (APS) as the oxidant. The morphology and structure of PANI were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The electrochemical performances of the supercapacitor assembled with PANI were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge. These results show that the specific capacitance of the M-PANI electrode prepared by MnO2 was about 260 F/g at the charge-discharge current density of 5 mA/cm2. After 500 charge-discharge cycles the specific capacitance of the M-PANI electrode was about 188 F/g and its capacitance retention is 72.3%. For comparison, M-PANI has better cycle performance and higher capacity than N-PANI, which was prepared by APS.(2) PANI-CNTs (abbr.M-PC) were prepared by chemical in-situ polymerization at ambient temperature, using MnO2 as the oxidant. The morphology and structure of M-PC were characterized by SEM, FTIR and XRD. The electrochemical performances of the supercapacitor assembled with M-PC were investigated by CV and galvanostatic charge-discharge. These results of galvanostatic charge-discharge experiment show that the specific capacitance of the M-PC decreases as the charge-discharge current density increases. The specific capacitance of the M-PC electrode is about 355 F/g at the charge-discharge current density of 5 mA/cm2. After 500 charge-discharge cycles the specific capacitance of the M-PC electrode is about 306 F/g and its capacitance retention is 86.2%. For comparison, M-PC has better cycle performance and higher capacity than N-PC, which was prepared by APS.(3) Co3O4 nanocubes were synthesized by solvothermal method in water and n-butanol solution, which polyethylene glycol was used as dispersant. PANI-Co3O4 composite material was prepared by chemical in-situ polymerization at ambient temperature, using MnO2 as the oxidant. The morphology and structure of PANI-Co3O4 were characterized by SEM, FTIR, and XRD. The electrochemical performances of the supercapacitor assembled with PANI-Co3O4 were investigated by cyclic voltammetry, and galvanostatic charge-discharge. These results show that the specific capacitance of the composite material of PANI-oO3O4 electrode was about 287 F/g at the charge-discharge current density of 5 mA/cm2. After 500 charge-discharge cycles the specific capacitance of the PANI-Co3O4 electrode was about 271 F/g. and its capacitance retention is 94.4%. For comparison, PANI-Co3O4 has better cycle performance and higher capacity than M-PANI.(4) Formic acid-doped PANI nanomaterils with different morphology had been synthesized successfully by interfacial polymerization with FeCl3 as oxidant and HCOOH as dopant. The morphology and structure of PANI were characterized by SEM, FTIR and XRD. Symmetric redox supercapacitor was assembled with the PANI as active electrode material and 1 mol/L H2SO4 aqueous solution as electrolyte. The electrochemical performances of the supercapacitor were investigated by CV and galvanostatic charge-discharge. These results show that PANI with different morphology depends on the concentration of HCOOH. PANI with fiber morphology has better power characteristic and cycle performance in the application of supercapacitor, whose specific capacitance is about 292 F/g at the current density of 15 mA/cm2. After 500 charge-discharge cycles its specific capacitance was about 201 F/g and its capacitance retention is 68.8%.更多还原