碳布基纳米复合材料的制备及其电化学特性

发布时间：2018-07-05 09:13

本文选题：二氧化锰 + 聚苯胺　；参考：《东华大学》2015年硕士论文

【摘要】：作为一种新兴的能源存储装置，超级电容器具有比电池更高的功率密度、更短的充电/放电时间和较长的循环寿命，拥有很好的发展前景。柔性超级电容器在可穿戴、小型化、便携式电子设备的储能元件上有潜在的应用价值，其中电极材料是决定超级电容器性能的关键。将一种或多种具有高赝电容的物质与不同结构碳材料通过一定的加工工艺制备成复合材料，有望使两者得到优势互补，从而制备具有较高电化学性能的新型电极材料。以不同结构的碳材料如石墨烯、碳纳米管、活性炭、碳纤维等作为基材制备自支撑电极材料受到较多关注，同时二氧化锰（MnO2）由于具有高比电容、资源广、价格低廉、制备简单和环境友好等特点，而聚苯胺（PANI）不仅具有上述优点外还具有高导电性，因此均受到广泛研究。本文选择具有一定机械强度、柔韧性和高导电的碳布（CC）作为碳材料基体，在其表面通过一定的化学及电化学合成方法分别制备了MnO2/CC、PANI/CC、MnO2/PANI/CC和PANI/MnO2/CC自支撑复合电极材料，并对其不同的形貌、结构及电化学性能进行了研究表征。首先将CC通过等离子体表面蚀刻处理后，以5mM KMnO4溶液作为锰源，CC同时作为还原剂和碳基体材料，采用水热反应制备MnO2/CC复合材料。通过控制水热反应时间，制备了一系列不同厚度的MnO2/CC复合材料，采用FESEM、Raman、XRD、XPS等手段对其结构和形貌进行了表征，并通过循环伏安、恒流充放电、交流阻抗等测试方法对其电化学性能进行了研究。结果表明，水热法制备复合材料MnO2形貌很难控制且分布不均匀，容易受到反应条件的影响，当反应时间为0.5h时，碳布表面形成球状花瓣二氧化锰，随着反应时间增加到1h MnO2在自身表面继续生长易形成棒状二氧化锰，并且杂乱无规地生长于碳布的表面。随着反应时间的增加，复合材料的比电容逐渐增加，但MnO2的利用率逐渐下降，当反应时间为0.5h时，材料的面积比电容达到76.9mF/cm2，而且循环1700圈后比电容仍保留89%，显示了较好的电化学性能。为了改善MnO2/CC复合材料表面MnO2的分布均匀性和形貌可控操作性，采用电化学沉积法，通过改变电化学沉积时间，制备出一系列不同厚度的MnO2/CC复合材料。实验结果表明，电化学沉积法制备的MnO2呈纳米球片状的形貌，而且在碳布纤维表面均匀分布，当沉积100s材料表面基本已经被MnO2包裹；随着沉积时间的延长，所沉积MnO2的片层结构变大，材料的比电容也随着MnO2负载量增加而增大。当沉积时间为2000s时复合材料的面积比电容可达291.7mF/cm2，但是MnO2表现出来的比电容随着MnO2层厚度的增加而降低，沉积400s时，在1A/g的电流密度下，MnO2表现出很高的比电容，为413.7F/g。材料的循环稳定性表现出一开始升高而后面稳定保持不变的趋势，在循环2000圈后比电容达到初始值得113%，显示了较好的循环稳定性，且相对于水热法制备得到的复合材料其稳定性有所提高。由于MnO2的导电性较差，负载导电聚合物有望改善复合材料的导电性，从而进一步提高材料的电化学性能。通过控制苯胺单体与氧化剂浓度，在一定的反应温度和时间下，采用原位聚合法制备了一系列PANI/CC复合材料。结果表明，，当单体与氧化剂摩尔比为3：1时有利于纳米线状聚苯胺的形成，当单体浓度超过0.015mmol/mL时，表面生长的聚苯胺薄膜形貌会坍塌。随着单体反应浓度的增加，复合材料的电化学性能出现先增大后减小的趋势，在单体浓度为1mmol/mL时，所制备的PANI/CC复合材料在0.2mA/cm2下的比电容高达225mF/cm2，但是倍率性较差，循环稳定性差循环1600圈比电容仅保持初始的63%。为进一步改善MnO2/CC复合材料的导电性和PANI/CC复合材料的循环稳定性，将MnO2和PANI按不同的顺序负载于CC表面，利用两者的协同作用进一步提高复合材料的电学性能。选用前期研究的较佳实验条件分别制备PANI/MnO2/CC、MnO2/PANI/CC两种不同层结构复合材料，结果表明，PANI/MnO2/CC材料中两种物质能够很好地相互嵌入交联，其中球状MnO2为PANI的生长提供了较大的生长空间，同时MnO2球间隙由纳米线状PANI连接，既起到增强两者粘结力又能提供高导电通道；而MnO2/PANI/CC中两种物质则是形成相对独立的存在，沉积时间较短时MnO2花球错落在PANI表面，当沉积时间达到400s时最外层的MnO2就把PANI层完全包覆。在三电极测试体系下以0.2mA/cm2扫速进行充放电测试， PANI/MnO2/CC的比电容达到421.6mF/cm2，而MnO2/PANI/CC只有284.7mF/cm2，且通过比较两种电极的倍率性能发现，前者在电流密度扩大5倍时比电容仍保持原来的63%，显示出良好的倍率性能，而后者只有原来的48.6%。
[Abstract]:As a new energy storage device, the supercapacitor has a higher power density than the battery, a shorter charge / discharge time and a longer cycle life. It has a good prospect of development. The flexible supercapacitor has potential application value in the wearable, miniaturized and portable electronic devices, in which the electrode materials are used. It is the key to determine the performance of supercapacitor. One or more materials with high pseudo capacitance and different structural carbon materials are prepared by a certain processing technology. It is expected to make the two more complementary and prepare a new electrode material with high electrochemical properties. Rice tube, activated carbon and carbon fiber have been paid more attention to the preparation of self supporting electrode materials as base materials. At the same time, manganese dioxide (MnO2) has the characteristics of high capacitance, wide resources, low price, simple preparation and friendly environment, and polyaniline (PANI) not only has the above advantages but also has high conductivity, so it has been widely studied in this paper. Carbon cloth (CC) with a certain mechanical strength, flexibility and high conductivity was selected as the matrix of carbon material. The self supported composite electrode materials of MnO2/CC, PANI/CC, MnO2/PANI/CC and PANI/MnO2/CC were prepared on its surface by chemical and electrochemical synthesis methods, and their different morphology, structure and electrochemical properties were studied. Sign.
After the CC is etched by plasma surface, 5mM KMnO4 solution is used as manganese source and CC is used as reducing agent and carbon matrix material to prepare MnO2/CC composites by hydrothermal reaction. A series of MnO2/CC composites with different thickness are prepared by controlling the time of hydrothermal reaction. The structure of the composite is composed of FESEM, Raman, XRD and XPS. The morphology was characterized and its electrochemical performance was studied by cyclic voltammetry, constant current charge discharge, and AC impedance. The results showed that the MnO2 morphology of the composites prepared by hydrothermal method was difficult to control and distributed unevenly, and was easily affected by the reaction conditions. When the reaction time was 0.5h, the spherical petals formed on the surface of the carbon cloth. As the reaction time increases to 1H MnO2, it is easy to form rod like manganese dioxide on its own surface, and it grows on the surface of carbon cloth randomly. With the increase of reaction time, the specific capacitance of the composite increases gradually, but the utilization of MnO2 gradually decreases. When the reaction time is 0.5h, the area of the material is higher than the capacitance. To 76.9mF/cm2, and after 1700 cycles, the capacitance is still 89%, indicating better electrochemical performance.
In order to improve the distribution uniformity and controllability of the surface MnO2 on the surface of MnO2/CC composite, a series of MnO2/CC composites with different thickness were prepared by electrochemical deposition and the electrochemical deposition time was changed. The results showed that the MnO2 prepared by electrochemical deposition was in the shape of nanospheres and on the carbon fiber sheet. The surface of the 100s material is evenly distributed when the surface of the deposited material is basically MnO2 wrapped. As the deposition time prolongs, the lamellar structure of the deposited MnO2 becomes larger and the specific capacitance of the material increases with the increase of the load of MnO2. When the deposition time is 2000s, the area of the composite can reach 291.7mF/cm2, but the specific capacitance shown by the MnO2 is followed by the capacitance. With the increase of the thickness of the MnO2 layer, when the current density of 1A/g is deposited, the MnO2 shows a high specific capacitance at the current density of 1A/g. It shows a trend that the cyclic stability of the 413.7F/g. material rises at the beginning and the stability remains unchanged at the back. After the cycle 2000 cycles, the specific capacitance is worth 113%, showing a better cycle stability and relative stability. The stability of the composites prepared by hydrothermal method has been improved.
Due to the poor conductivity of MnO2, the load conducting polymer is expected to improve the conductivity of the composite material and further improve the electrochemical performance of the material. By controlling the concentration of aniline monomer and oxidant, a series of PANI/CC composites are prepared by in-situ polymerization at a certain reaction temperature and time. The results show that the monomer and the monomer are used as the monomers. When the molar ratio of oxidizer is 3:1, it is beneficial to the formation of nanoscale polyaniline. When the monomer concentration exceeds 0.015mmol/mL, the surface morphology of the polyaniline film will collapse. With the increase of the monomer reaction concentration, the electrochemical performance of the composite increases first and then decreases. When the monomer concentration is 1mmol/mL, the prepared PANI/CC is made. The specific capacitance of the composite material under 0.2mA/cm2 is as high as 225mF/cm2, but the rate is poor, and the cycle stability is poor. Compared to the 1600 cycle cycle, the capacitance keeps only the initial 63%..
In order to further improve the conductivity of MnO2/CC composites and the cyclic stability of PANI/CC composites, MnO2 and PANI are loaded on the CC surface in different order, and the electrical properties of the composites are further improved by the synergistic effect of both. The better experimental conditions of the previous study are made to prepare PANI/MnO2/CC and MnO2/PANI/CC in two different kinds. The results show that the two materials in the PANI/MnO2/CC material can be intercalalized well with each other, in which the spherical MnO2 provides a larger growth space for the growth of PANI, and the MnO2 sphere gap is connected by the nanoscale PANI, which can enhance both the bonding force and the high conduction channel, while the two in MnO2/PANI/CC. The quality is a relatively independent existence, when the deposition time is shorter, the MnO2 flower ball falls on the PANI surface. When the time of deposition reaches 400s, the PANI layer is completely covered with the PANI layer. Under the three electrode test system, the charge and discharge test is carried out at 0.2mA/cm2 sweep speed, PANI/MnO2/CC's specific electrical capacity reaches 421.6mF/cm2, and MnO2/PANI/CC only 284.7mF/cm is 284.7mF/cm. 2, and by comparing the ratio performance of the two electrodes, it is found that the former is still 63% when the current density is 5 times larger than the capacitance, showing a good multiplier performance, and the latter only has the original 48.6%..
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;TB33

【参考文献】