掺杂聚吡咯及其复合材料的电化学合成与电化学性能研究

发布时间：2019-03-09 12:13

【摘要】：面对目前越来越严峻的能源问题,人们急于寻求一种高效的储能装置来实现能量的有效利用。超级电容器的出现改变了二次电池功率密度低和普通电容器能量密度低的限制,成为各领域的研究热点。电极材料的选择决定着超级电容器性能的优劣。导电高分子聚吡咯(PPy)由于具有成本低、合成方法简单、氧化电位低和稳定性好等特点,因而是超级电容器中研究较为普遍的一种电极材料。本征态聚吡咯导电性较差,但其处于掺杂态时导电性提高,电化学活性增强。为了优化聚吡咯的电化学性能,本文通过循环伏安法在酸性体系中合成了掺杂聚吡咯和多壁碳纳米管改性的掺杂聚吡咯电极材料,采用傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、场发射扫描电镜(SEM)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)对其结构和形貌进行表征,并通过循环伏安(CV)、恒流充放电(GCD)、交流阻抗(EIS)等测试方法对其电化学性能进行了研究。主要内容如下:(1)分别以H_2SO_4和HNO_3作为聚合电解液,通过循环伏安法在不锈钢网上合成了质子酸掺杂的聚吡咯(PPy)。研究了其微观形貌、结构和电化学性能。结果表明,PPy/HNO_3电极材料具有疏松多孔的珊瑚状结构,而PPy/H_2SO_4呈现出菜花状结构;电流密度为5 m A cm~(-2)时,在0.5 mol L~(-1)(M)H_2SO_4电解液中,PPy/0.5M HNO_3比电容为596 F g~(-1),循环1000次后比电容保持了95.9%,在1.0 M HNO_3电解液中,PPy/0.1 M H_2SO_4比电容为442 F g~(-1),循环1000次后比电容保持了70.6%,相比之下,HNO_3掺杂后的聚吡咯电极材料表现出更优异的电化学性能。(2)在硫酸介质中以吡咯为单体,以三种不同过渡金属离子(Ni~(2+)、Fe~(2+)和Cu~(2+))为掺杂剂,采用循环伏安法在不锈钢网上合成了三种过渡金属离子掺杂的聚吡咯电极材料。研究了其电化学性能,并探讨了过渡金属离子的性质对聚吡咯性能的影响。结果表明,电流密度为5 m A cm~(-2)时,在1.0 M HNO_3电解液中,PPy/0.1M Ni~(2+)、PPy/0.5 M Fe~(2+)和PPy/0.1 M Cu~(2+)电极材料的比电容分别为517、679和764F g~(-1),循环1000次后比电容分别保持了80.5%、82.7%和83.8%。过渡金属离子半径越小,离子势越大,电极材料的比电容越大。(3)在上述(2)的基础上,采用混酸处理的多壁碳纳米管(MWCNTs)浸渍不锈钢网,并用循环伏安法在其上制备了Cu~(2+)掺杂的聚吡咯/多壁碳纳米管复合电极材料。系统研究了碳纳米管的引入对聚吡咯电化学性能的影响。结果表明,PPy与MWCNTs形成了一种核-壳结构的复合材料,混酸处理MWCNTs回流时间为1h、沉积电解液中多壁碳纳米管的加入量为0.8%时,复合材料的比电容为1269 F g~(-1),在扫速为50 m V s~(-1)下经过1000次循环后的比电容保持率为88.1%。
[Abstract]:In the face of more and more serious energy problems, people are eager to seek an efficient energy storage device to realize the effective utilization of energy. The emergence of supercapacitors has changed the limitations of low power density of secondary batteries and low energy density of ordinary capacitors, and has become a research hotspot in various fields. The selection of electrode material determines the performance of supercapacitor. Conductive polymer polypyrrole (PPy) is a widely used electrode material in supercapacitors due to its low cost, simple synthesis method, low oxidation potential and good stability. The intrinsic state of polypyrrole is poor in conductivity, but in the doped state, the conductivity and electrochemical activity of polypyrrole are enhanced. In order to optimize the electrochemical performance of polypyrrole, doped polypyrrole and multi-walled carbon nanotubes modified polypyrrole electrode materials were synthesized by cyclic voltammetry in acidic system. Fourier transform infrared spectroscopy (FT-IR) was used. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM),) transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure and morphology of the (GCD),. The structure and morphology were characterized by cyclic voltammetry (CV), constant current charge-discharge (GCD),. The electrochemical properties were studied by AC impedance (EIS) and other methods. The main contents are as follows: (1) the protonic acid doped polypyrrole (PPy). Was synthesized on stainless steel by cyclic voltammetry using H_2SO_4 and HNO_3 as polymerization electrolyte respectively. The microstructure, structure and electrochemical properties were studied. The results show that the PPy/HNO_3 electrode material has a porous coral-like structure, while PPy/H_2SO_4 has a cauliflower-like structure. When the current density is 5 Ma cm~ (- 2), the specific capacitance of PPy/0.5M HNO_3 in 0.5 mol L ~ (- 1) (M) H_2SO_4 electrolyte is 596 F 路g ~ (- 1), and the specific capacitance is 95.9% after 1000 cycles. In 1.0m HNO_3 electrolyte, the specific capacitance of PPy/0.1 M H_2SO_4 is 442F g ~ (- 1), and the specific capacitance is 70.6% after 1000 cycles. The polypyrrole electrode materials doped with HNO_3 exhibited better electrochemical properties. (2) using pyrrole as monomer in sulfuric acid medium, three different transition metal ions (Ni~ (2), Fe~ (2) and Cu~ (2) were used as dopants. Three transition metal ion doped polypyrrole electrode materials were synthesized by cyclic voltammetry on stainless steel net. The electrochemical properties of polypyrrole were studied and the effects of transition metal ions on polypyrrole were investigated. The results show that when the current density is 5 Ma cm~ (- 2), in 1.0m HNO_3 electrolyte, PPy/0.1M Ni~ (2), The specific capacitance of PPy/0.5 M Fe~ (2) and PPy/0.1 M Cu~ (2) electrode materials is 517679 and 764 F g ~ (- 1), respectively. After 1000 cycles, the specific capacitance remains 80.5%, 82.7% and 83.8% respectively. The smaller the radius of transition metal ions and the larger the neutron potential, the larger the specific capacitance of the electrode material. (3) on the basis of the above (2), multi-walled carbon nanotubes (MWCNTs) impregnated stainless steel mesh with mixed acid treatment. Cu~ (2)-doped polypyrrole / multi-walled carbon nanotubes composite electrode materials were prepared by cyclic voltammetry. The effect of carbon nanotubes on the electrochemical properties of polypyrrole was systematically studied. The results showed that PPy and MWCNTs formed a core-shell structure composite. The refluxing time of MWCNTs treated with mixed acid was 1 h, and the specific capacitance of the composite was 1269 F g ~ (- 1) when the amount of multi-walled carbon nanotubes in the deposition electrolyte was 0.8%, and the specific capacitance of the composite was 1269 F 路g ~ (- 1). The specific capacitance retention rate is 88.1% after 1000 cycles at a sweep rate of 50 MV Ss ~ (- 1).
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O633.5;TB332;O646

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