碳纳米管 石墨烯基复合材料的制备及其电化学性能

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3.0 侯斌 2024-11-19 4 4 14.26MB 67 页 15积分
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摘 要
超级电容器是一种性能优异、绿色环保的新型储能元件，而电极材料作为其
核心部分对其电化学性能起着决定性的影响。本论文主要围绕碳纳米管（CNTs）/
氧化石墨烯（GO）/二氧化锰（MnO2）三元复合电极材料的制备与性能优化展开
研究。
碳纳米管一直被认为是理想的超级电容器电极材料。然而，纯 CNTs 的比电容
一般较小。此外，碳纳米管之间范德华力的存在使 CNTs 表现出团聚现象，增加了
分散难度，影响了电化学性能。
本论文以单壁碳纳米管作为合成电容器电极材料的基础材料，以氧化石墨烯
提高 SWCNTs 的分散性，以 MnO2来增强其比电容，通过微波法合成了三元复合
材料，并探讨了微波合成法和水热合成法两种不同合成方式对材料电容性能的影
响。采用拉曼光谱、X射线衍射、热重、扫描电子显微镜和透射电子显微镜对复
合结构电极材料进行表征，利用循环伏安、恒流充放电、交流阻抗等技术对其电
化学性能进行测试，取得如下研究结果：
1、分别研究了几种不同材料的电化学性能。纯 SWCNTs 电极显示出了典型
的双电层特性，但比电容较小，仅为 73.8 F/g；
SWCNTs/MnO2二元复合材料因 MnO2
的加入比电容有所提高，但因 SWCNTs 不能为 MnO2提供足够的负载位点导致复
合材料宏观结构不均均匀；而 SWCNTs/GO/ MnO2复合材料微观结构均匀，MnO2
负载量高，电化学性能优良。
2、系统研究了 SWCNTs/GO/MnO2三元复合材料的合成条件与电化学性能的
关联性。结果表明，当高锰酸钾的浓度为 9 mM（复合材料中 MnO2的含量为 64.2%）、
微波温度为 100℃、微波时间 60 min、SWCNTs/GO 为1:1 时，复合材料表现出最
优的电化学性能，即在 0.2 A/g 的电流密度下，其比电容可达 173 F/g。
3、探讨了合成方式对材料性能的影响。在相同的实验条件下，分别采用微
波法和水热法合成复合材料，结果表明相比于水热合成方式，微波合成法效率更
高（1 h vs.10 h），材料微观结构更均匀，比电容更高(173 F/g vs.139 F/g），电极材
料的电荷转移电阻更小（1.425 Ω vs.1.913 Ω），电容损失率更低（3.74% vs.11%）。
本文通过微波合成法和水热合成法的对比，得出微波合成法在较短的时间内
能合成出微观结构均匀、电化学性能优良的电极材料，为今后合成性能优良的电
极材料提供了借鉴。
关键词： 碳纳米管 复合材料 微波 水热 电化学性能
ABSTRACT
As a novel environmentally friendly energy-storage component, supercapacitor
exhibits outstanding performance that is strongly dependent on the electrode materials
of which the capacitor is made. This thesis focuses on the synthesis of ternary
composite electrode materials composed of single-walled carbon nanotubes
(SWCNTs) ，graphene oxide (GO) and manganese dioxide (MnO2), as well as the
optimization of experimental conditions .
Due to the unique properties, carbon nanotubes are regarded as one of promising
electrode materials for supercapacitors. However, pure CNTs exhibit relatively lower
specific capacitance because of the aggregation into bundles induced by van der Waals
forces, and thus worse the dispersibility.
In this thesis, efforts were focused on the synthesis of ternary carbon-based
composites in which SWCNTs served as a primary compositon, graphene oxide (GO)
was used to improve the dispersion of SWCNTs, while manganese dioxide (MnO2) was
prepared to increase the specific capacitance. The composites were prepared by the
traditional hydrothermal method and microwave-assisted method, respectively. Effects
was compared and systematically discussed. The morpholorgy and microstrcuture of
samples were characterized by Raman spectropy, X-ray difraction (XRD),
thermogravimetric analysis (TGA), scanning electronic microscopy (SEM) and
transmission electronic microscopy (TEM). The electrochemical properties were
investigated by cyclic voltammetry (CV), galvanostatic charge/discharge measurements
(GCD) and electrochemical impedance spectroscopy (EIS).
The achievements are specifically as follows:
1. The electrochemical properties of several different materials were investigated,
respectively. Pure SWCNTs characterize a typical electrical double-layer capacitor
property with a low specific capacitance of 73.8 F/g. With the presence of MnO2, the
composite of SWCNTs/MnO2exhibits a higher specific capacitance than the pure
SWCNTs. However the compositions are not so homogeneous since SWCNTs can’t
provide enough surface area for the loading of MnO2. The ternary composite of
SWCNTs/GO/MnO2possesses uniform microstructure, high MnO2loading, and thus
displays excellent electrochemical performance.
2. The corralation between the microwave-assisted synthetic conditions and
electrochemical properties of SWCNTs/GO/MnO2were demonstrated. The optimized
experimental condition, 22 mg addition of KMnO4corresponding to a 64.2 wt% loading
of MnO2, microwave temperature of 100 ℃, operation time of 60 mins and same
fraction of SWCNTs and GO, favors the formation of SWCNTs/GO/MnO2with the
best electrochemical performance of 173 F/g at 0.2 A/g.
3. Effects of microwave irradiation and hydrothermal treatments on synthesising
composites were studied. Results indicate that microwave method exhibits much higher
efficiency (1 h vs. 10 h), better homogeneity of microstructures, more excellent specific
capacitance (173 F/g vs. 139 F/g), less charge transfer resistance (1.425 Ω vs. 1.913 Ω),
and lower loss rate of capacitance (3.74% vs. 11%).
In summary, the thesis studied the effects of microwave and hydrothermal
synthetic methods on microstructure and electrochemical properties of SWCNTs-based
electrode materials. It was found that materials can be efficiently prepared by
microwave method with uniform microstructures and excellent electrochemical
performance, which paves the way for pareparing high performance electrode materials
in future.
Key Word: carbon nanotubes, composite material, microwave,
hydrothermal, electrochemical performance
目 录
中文摘要
ABSTRACT
第一章 绪 论................................................................................................................... 1
1.1 概述.........................................................................................................................1
1.1.1 超级电容器的储能原理.................................................................................. 1
1.1.2 超级电容器的特点.......................................................................................... 2
1.2 超级电容器电极材料.............................................................................................3
1.2.1 碳材料.............................................................................................................. 3
1.2.2 金属氧化物材料.............................................................................................. 4
1.2.3 导电聚合物材料.............................................................................................. 4
1.3 碳复合电极材料研究现状.....................................................................................5
1.3.1 碳纳米管/二氧化锰......................................................................................... 5
1.3.2 石墨烯/二氧化锰............................................................................................. 6
1.3.3 碳纳米管/氧化石墨烯/二氧化锰.....................................................................7
1.4 微波技术在超级电容器电极材料中的应用.........................................................7
1.5 本文研究内容.........................................................................................................8
第二章 实验部分........................................................................................................... 10
2.1 实验试剂及仪器...................................................................................................10
2.1.1 实验试剂........................................................................................................ 10
2.1.2 实验仪器........................................................................................................ 10
2.2 实验内容...............................................................................................................11
2.2.1 氧化石墨烯的制备........................................................................................ 11
2.2.2 碳纳米管的功能化........................................................................................ 11
2.2.3 复合材料的制备............................................................................................ 12
2.2.4 电极的组装.................................................................................................... 12
2.3 材料表征...............................................................................................................12
2.3.1 场发射扫描电子显微镜................................................................................ 12
2.3.2 透射电子显微镜............................................................................................ 12
2.3.3 热重................................................................................................................ 12
2.3.4 拉曼光谱........................................................................................................ 12
2.3.5 X 射线衍射..................................................................................................... 13
2.3.6 电化学性能.................................................................................................... 13
第三章 材料的合成及性能........................................................................................... 15
3.1 引言.......................................................................................................................15
3.2 单壁碳纳米管及其复合材料的表征及性能........................................................15
3.2.1 实验流程........................................................................................................ 15
3.2.2 形貌与结构表征............................................................................................ 15
3.2.3 电化学性能.................................................................................................... 18
3.3 高锰酸钾浓度对电化学性能的影响...................................................................22
3.3.1 结构与性能表征............................................................................................ 23
3.3.2 电化学性能.................................................................................................... 24
3.4 微波反应温度对电化学性能的影响...................................................................28
3.4.1 形貌及结构表征............................................................................................ 29
3.4.2 电化学性能.................................................................................................... 31
3.5 微波反应时间对电化学性能的影响...................................................................33
3.5.1 形貌与结构表征............................................................................................ 34
3.5.2 电化学性能.................................................................................................... 35
3.6 不同单壁碳纳米管/氧化石墨烯比例对电化学性能的影响............................. 38
3.6.1 形貌与结构表征............................................................................................ 38
3.6.2 电化学性能.................................................................................................... 39
3.7 本章小结...............................................................................................................43
第四章 合成方式对复合材料结构及电化学性能的影响........................................... 45
4.1 引言.......................................................................................................................45
4.2 实验流程...............................................................................................................45
4.3 结果与讨论...........................................................................................................46
4.3.1 微观形貌与结构表征.................................................................................... 46
4.3.2 电化学性能.................................................................................................... 49
4.4 结论.......................................................................................................................51
第五章 结论与展望....................................................................................................... 53
5.1 结论.......................................................................................................................53
5.2 展望.......................................................................................................................54
参考文献......................................................................................................................... 55
在读期间公开发表的论文和承担科研项目及取得成果............................................. 62
致 谢............................................................................................................................. 63
摘要：

摘要超级电容器是一种性能优异、绿色环保的新型储能元件，而电极材料作为其核心部分对其电化学性能起着决定性的影响。本论文主要围绕碳纳米管（CNTs）/氧化石墨烯（GO）/二氧化锰（MnO2）三元复合电极材料的制备与性能优化展开研究。碳纳米管一直被认为是理想的超级电容器电极材料。然而，纯CNTs的比电容一般较小。此外，碳纳米管之间范德华力的存在使CNTs表现出团聚现象，增加了分散难度，影响了电化学性能。本论文以单壁碳纳米管作为合成电容器电极材料的基础材料，以氧化石墨烯提高SWCNTs的分散性，以MnO2来增强其比电容，通过微波法合成了三元复合材料，并探讨了微波合成法和水热合成法两种不同合成方式对材料...

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作者：侯斌 分类：高等教育资料 价格：15积分 属性：67 页 大小：14.26MB 格式：PDF 时间：2024-11-19

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