片状多孔碳材料的结构调控及电化学性质研究
发布时间：2018-10-10 17:46
【摘要】：碳材料具有良好的导电性和机械性能、结构稳定及形态丰富等特点,可以在锂离子电池和超级电容器等高效储能器件中构筑能量储存和输运网络,从而发挥着不可或缺的重要作用。片状多孔碳材料的可控制备是增加碳基材料的储能活性位点、构筑更加高效便利的电荷传输通道的重要途径,也是进一步提高储能器件功率密度和能量密度的重要手段。本论文针对当前储能电极材料存在的问题,结合碳材料在锂离子电池和超级电容器中发挥的作用,通过结构设计和可控制备,获得一系列具有高效离子传输通道和导电网络结构的片状多孔碳基材料,并将其应用于高效储能器件中;在此基础上发展了多种片状多孔碳材料的制备方法,并对其形成机理进行分析阐释,从而实现了片状多孔碳材料微观结构的精确调控。针对高比容量锡基材料用作锂离子电池负极存在导电性差和充放电过程中的体积效应等问题,制备了碳包覆空心锡与石墨烯杂化材料,通过利用各组分之间的协同效应实现了锡基杂化材料电化学性能的优化,其首次可逆容量达922.7mAh g-1,经50次循环后容量保持率为71.5%。研究并发展了片状多孔碳材料的三种制备方法:一步碳化法、直接活化及模板法。通过一步碳化处理生物质获得高比表面积的片状多孔碳材料。改变碳化温度即可对孔结构进行有效调节,适用于不同的电解液体系。BCY-800在6 M KOH电解液体系下比容量高达216 F g-1,其在20 A g-1下的容量保持率为0.5 A g-1时的84%;BCY-900在离子液体体系中290 W L-1时对应的体积能量密度为64.6 Wh L-1,在3065 W L-1时体积能量密度仍高达34 Wh L-1。通过直接活化法实现片状层次孔碳材料的可控制备。通过改变活化路径实现了球形低聚物向片状层次孔碳材料的转变,并探讨了其形成机理。球形低聚物的表面化学、活化温度和活化剂的添加量对结构的形成非常重要。片状层次孔碳具有大比表面积(2633 m2 g-1)和相互贯通的多层级孔结构等特征,在100 A g-1的大电流密度下其容量仍达184 F g-1,为0.5 A g-1下容量的71.6%;在1 A g-1的电流密度下循环2000圈后的容量保持率为98%。通过氧化石墨烯的模板诱导作用实现对生物质原料水热产物结构和形貌的调控。利用KOH活化处理,获得了比表面积达3257 m2 g-1的片状多孔碳材料,在1000 mV s-1的高扫速下,材料的循环伏安曲线仍能保持良好的矩形形状。
[Abstract]:Carbon materials have good electrical conductivity and mechanical properties, stable structure and rich shape. They can be used to build energy storage and transport network in high-efficiency energy storage devices such as lithium-ion batteries and supercapacitors. Thus play an indispensable and important role. The controllable preparation of sheet porous carbon materials is an important way to increase the energy storage activity sites of carbon based materials and to construct more efficient and convenient charge transfer channels. It is also an important means to further improve the power density and energy density of energy storage devices. In this paper, considering the problems existing in the materials of energy storage electrodes and the role of carbon materials in lithium ion batteries and supercapacitors, the structure design and controllable fabrication are adopted. A series of sheet porous carbon based materials with high efficiency ion transport channels and conductive network structure were obtained and applied to high efficiency energy storage devices. The formation mechanism was analyzed and explained, thus the precise regulation of the microstructure of porous carbon flake materials was realized. In order to solve the problems of poor conductivity and volume effect during charge and discharge of high specific capacity tin based materials used as anode of lithium ion batteries, carbon coated hollow tin and graphene hybrid materials were prepared. The electrochemical performance of tin based hybrid materials was optimized by using the synergistic effect of each component. The first reversible capacity of the hybrid material was up to 922.7mAh g-1, and the capacity retention rate was 71.5 after 50 cycles. Three preparation methods of sheet porous carbon materials were studied and developed: one step carbonization method, direct activation method and template method. Sheet porous carbon materials with high specific surface area were obtained by one step carbonization of biomass. The pore structure can be adjusted effectively by changing the carbonation temperature. It is suitable for different electrolyte systems. The specific capacity of BCY-800 in 6 M KOH electrolyte system is up to 216F g-1, and the volume energy density of BCY-900 in ionic liquid system at 290W L-1 is 84 when the capacity retention at 20A g ~ (-1) is 0.5 A g ~ (-1). The volume energy density is still up to 34 Wh L ~ (-1) at 3065 W ~ (-1). The controllable preparation of lamellar layered porous carbon materials was realized by direct activation method. The transition of spherical oligomers to lamellar porous carbon materials was realized by changing the activation path, and its formation mechanism was discussed. Surface chemistry, activation temperature and the amount of activator are very important for the formation of the structure of spherical oligomer. The flake layered porous carbon has the characteristics of large specific surface area (2633 m2 g ~ (-1) and interpenetrating multi-layer pore structure. At the high current density of 100A g ~ (-1), the capacity is still 184 F g ~ (-1), which is 71.6% of the capacity at 0.5 A g ~ (-1), and the capacity retention rate is 98% after cycling for 2000 cycles at the current density of 1 A g ~ (-1). The structure and morphology of hydrothermal products from biomass were regulated by template induction of graphene oxide. A sheet porous carbon material with a specific surface area of 3257 m2 / g ~ (-1) was obtained by KOH activation treatment. The cyclic voltammetry curve of the material remained a good rectangular shape at a high sweep rate of 1000 mV / s ~ (-1).
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ127.11
，
本文编号：2262714
[Abstract]:Carbon materials have good electrical conductivity and mechanical properties, stable structure and rich shape. They can be used to build energy storage and transport network in high-efficiency energy storage devices such as lithium-ion batteries and supercapacitors. Thus play an indispensable and important role. The controllable preparation of sheet porous carbon materials is an important way to increase the energy storage activity sites of carbon based materials and to construct more efficient and convenient charge transfer channels. It is also an important means to further improve the power density and energy density of energy storage devices. In this paper, considering the problems existing in the materials of energy storage electrodes and the role of carbon materials in lithium ion batteries and supercapacitors, the structure design and controllable fabrication are adopted. A series of sheet porous carbon based materials with high efficiency ion transport channels and conductive network structure were obtained and applied to high efficiency energy storage devices. The formation mechanism was analyzed and explained, thus the precise regulation of the microstructure of porous carbon flake materials was realized. In order to solve the problems of poor conductivity and volume effect during charge and discharge of high specific capacity tin based materials used as anode of lithium ion batteries, carbon coated hollow tin and graphene hybrid materials were prepared. The electrochemical performance of tin based hybrid materials was optimized by using the synergistic effect of each component. The first reversible capacity of the hybrid material was up to 922.7mAh g-1, and the capacity retention rate was 71.5 after 50 cycles. Three preparation methods of sheet porous carbon materials were studied and developed: one step carbonization method, direct activation method and template method. Sheet porous carbon materials with high specific surface area were obtained by one step carbonization of biomass. The pore structure can be adjusted effectively by changing the carbonation temperature. It is suitable for different electrolyte systems. The specific capacity of BCY-800 in 6 M KOH electrolyte system is up to 216F g-1, and the volume energy density of BCY-900 in ionic liquid system at 290W L-1 is 84 when the capacity retention at 20A g ~ (-1) is 0.5 A g ~ (-1). The volume energy density is still up to 34 Wh L ~ (-1) at 3065 W ~ (-1). The controllable preparation of lamellar layered porous carbon materials was realized by direct activation method. The transition of spherical oligomers to lamellar porous carbon materials was realized by changing the activation path, and its formation mechanism was discussed. Surface chemistry, activation temperature and the amount of activator are very important for the formation of the structure of spherical oligomer. The flake layered porous carbon has the characteristics of large specific surface area (2633 m2 g ~ (-1) and interpenetrating multi-layer pore structure. At the high current density of 100A g ~ (-1), the capacity is still 184 F g ~ (-1), which is 71.6% of the capacity at 0.5 A g ~ (-1), and the capacity retention rate is 98% after cycling for 2000 cycles at the current density of 1 A g ~ (-1). The structure and morphology of hydrothermal products from biomass were regulated by template induction of graphene oxide. A sheet porous carbon material with a specific surface area of 3257 m2 / g ~ (-1) was obtained by KOH activation treatment. The cyclic voltammetry curve of the material remained a good rectangular shape at a high sweep rate of 1000 mV / s ~ (-1).
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ127.11
，
本文编号：2262714
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