具有分级结构的生物质多孔炭的制备及其电化学电容性质研究

发布时间：2018-01-16 16:22

本文关键词：具有分级结构的生物质多孔炭的制备及其电化学电容性质研究　出处：《南昌航空大学》2017年硕士论文　论文类型：学位论文

【摘要】：能源问题是全世界都关心的一个主题,并且随着全球经济的发展会更加重视这一问题。世界的发展和经济的全球化、现代化,离不开化石能源,如石油、天然气、煤炭的广泛应用。全世界对工业化速度的追求,导致了能源的消耗速度也大大加快,据相关报道,化石能源在21世纪上半世纪将会严重匮乏,全球能源危机问题将会日益突出。此外,化石燃料的使用还导致了严重的环境问题。能源危机和环境问题对人类的生存和发展直接构成威胁。因此,发展可持续的清洁能源和研究先进能源存储技术已成为一个非常紧迫的问题,超级电容器的出现为可持续发展提供了可能。超级电容器是一种独特的电能存储设备,不仅能提供的能量密度比传统电容器大几个数量级,而且比传统电池具有更高的功率密度和更好的循环性能。电极材料对超级电容器的性能起到至关重要的作用。近年来,以生物质为碳源,是该领域的一个研究热点。本论文以三种生物质材料为前驱体,通过不同的合成方法制备出多种不同形貌、结构的多孔碳材料,并对其电容性能进行了研究。1.以柚子皮为原料,采用冷冻干燥保持柚子皮原有微结构,在此基础上,通过炭化、KOH活化获得了泡沫状炭片,通过SEM观察发现该炭片是由孔径约为20μm的炭管相互交联在一起组成的。将该炭片直接作为工作电极进行电化学测试,结果表明,在6M KOH溶液中,在电流密度为1 Ag~（-1）条件下比容量高达338 Fg~（-1）;当电流密度达到20 Ag~（-1）,比容量仍有200 Fg~（-1）。此外,炭片组成的对称超级电容器在功率密度为250 Wkg~（-1）时能量密度为11.05 Whkg~（-1）。该电容器在电流密度为5 Ag~（-1）时经过5000次充放电循环后,其容量只降低2.4%,说明由炭片组成的对称超级电容器具有良好的循环稳定性。2.以胖大海为碳源,采用水热炭化获得前驱体,再用KOH对其进一步活化,获得氮掺杂的多孔炭。通过改变活化温度或活化剂与前驱体的比例,结果表明当活化温度为800oC、活化剂与前驱体的比例为1时,获得的多孔炭具有最优的电化学性能。当电流密度为1 Ag~（-1）比容量高达337 Fg~（-1）。当电流密度增加到50 Ag~（-1）时,比容量仍保持有181.5 Fg~（-1）。该多孔炭材料组装成的对称电容器在电流密度为20 Ag~（-1）时经过10000次充放电循环后,其容量保持率高达98%。研究结果发现该多孔炭材料所具备的优异的电化学性能主要归因于材料的分级多孔结构、窄的孔径分布、合理的微/介孔比例以及N原子的掺杂。3.以桂花为原料,采用水热炭化获得水热炭,再用KOH对其进一步活化,获得蜂窝状的多孔炭。通过改变活化剂与水热炭的比例,结果表明,当活化剂与水热炭的比例为2:1时,获得的蜂窝状多孔炭具有最优的电化学性能。当电流密度为1 Ag~（-1）比容量高达262 Fg~（-1）。蜂窝状多孔炭组成的对称电容器的容量从1 Ag~（-1）的70 Fg~（-1）降低到20 Ag~（-1）的60.2 Fg~（-1）,容量保持率高达85.7%,说明其具有良好的倍率性能。此外,在20 Ag~（-1）的电流密度下经过10000次充放电循环,容量仅损失1.6%,说明对称电容器具有良好的循环稳定性。
[Abstract]:The energy problem is a topic all over the world are concerned, and with the development of the global economy will pay more attention to this problem. The development of the world and economic globalization, modernization, cannot do without fossil fuels, such as petroleum, natural gas, coal is widely used. The industrialization speed of the pursuit of the whole world, resulting in energy the consumption rate is greatly accelerated, according to reports, the fossil energy in the first half of twenty-first Century will be in serious shortage of global energy crisis will become increasingly prominent. In addition, the use of fossil fuels has led to serious environmental problems. The energy crisis and environmental problems to human survival and development of the direct threat. Therefore, the development of sustainable clean study on energy and advanced energy storage technology has become a very urgent problem, the super capacitor provides the possibility for sustainable development. The super capacitor is a unique The electric energy storage device, not only can provide high energy density than conventional capacitors several orders of magnitude, the cycle performance and has higher power density and better than conventional batteries. The performance of super capacitor electrode materials play a crucial role. In recent years, with the biomass as a carbon source, is a the research focus in the field. In this paper, three kinds of biomass materials as precursors by different synthesis methods were prepared by different kinds of morphology, structure of porous carbon materials, and the capacitance properties were studied by.1. pomelo peel as raw material, using freeze drying to maintain the grapefruit skin micro structure on the basis of the original., through carbonization, activation of KOH obtained foamy carbon films, observed by SEM found that the carbon sheet is composed of an aperture is about 20 m of the carbon tube cross-linking together. The carbon plate is directly used as the working electrode for electrochemical test. The results show that in 6M KOH solution, the current density of 1 Ag~ (-1) under the condition of high specific capacity of 338 Fg~ (-1); when the current density reaches 20 Ag~ (-1), 200 Fg~ (-1) specific capacity. In addition, the super capacitor carbon film composed of symmetry in power density 250 Wkg~ (-1) when the energy density of 11.05 Whkg~ (-1). The capacitor at a current density of 5 Ag~ (-1) after 5000 cycles, the capacity decreased only 2.4%, indicating the super capacitor consists of a carbon film with symmetric.2. good cycling stability using seed as carbon source. To obtain the precursor by hydrothermal carbonization, and activation of the KOH further, obtain nitrogen doped porous carbon. By changing the activation temperature and activation agents and precursors of the proportion, the result shows that when the activation temperature is 800oC, activation agents and precursors of the proportion is 1, porous carbon obtained has excellent electrochemical performance when the current density is 1. Ag~ (-1) than the capacity of up to 337 Fg~ (-1). When the current density increased to 50 Ag~ (-1), the capacity remains 181.5 Fg~ (-1). The symmetric capacitor of the porous carbon materials assembled at a current density of 20 Ag~ (-1) after 10000 cycles, the capacity retention rate of 98%. results showed that the electrochemical performance of the porous structure of porous carbon material with excellent material is mainly attributed to the narrow pore size distribution, reasonable micro / mesoporous ratio and N doping.3. with sweet scented osmanthus as raw material, hydrothermal carbon by hydrothermal carbonization, and KOH further activation of the porous carbon honeycomb. By changing the proportion of activated carbon, agent and water heat. The results show that when the activator and hot water carbon ratio is 2:1, the electrochemical properties of honeycomb porous carbon obtained is optimal. When the current density is 1 Ag~ (-1) than the capacity of up to 262 Fg~ (-1 ). Symmetric capacitor composed of the honeycomb porous carbon capacity from 1 Ag~ (-1) 70 Fg~ (-1) reduced to 20 Ag~ (-1) 60.2 Fg~ (-1), the capacity retention rate of 85.7%, indicating a good rate capability. In addition, in 20 Ag~ (-1) current density after 10000 cycles, the capacity loss is only 1.6%, that asymmetric capacitor has a good cycle stability.

【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TM53

【参考文献】