改性石墨烯的设计制备及电化学储能研究

发布时间：2018-03-18 08:42

本文选题：锂离子电池　切入点：钠离子电池　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：为了保证航天器的各种仪表设备正常运行,需要航天电源系统支持。化学能源是航天电源系统的重要组成部分,其包括各种离子电池和燃料电池。针对复杂的空间环境,化学能源目前主要的研究重点之一是开发高容量、高稳定性电池电极材料。石墨烯作为一种二维层状材料,具有大的比表面积、高的导电性等特点在各种电化学储能器件方面有潜在的应用。本文以制备高性能电池电极材料为目标,以改性石墨烯为研究对象,设计开发了多种可控制备改性石墨烯的方法,最终实现高的电化学性能。为了缓解锂电池电极材料导电性差和在充放电过程中体积效应引起的容量衰减问题,本文首先开发了一种加热-淬火循环制备3D多孔石墨烯的方法,所得产物具有大的比表面积和高的导电性。利用所得3D多孔石墨烯与P25(Ti O2)复合用于锂离子电池阳极时,在室温下循环50圈后,所得容量为130 mAh g-1是相同条件下纯P25容量的5.2倍。进一步在0 oC低温和40 oC高温时循环50圈后,复合材料的容量分别为91.7和89.1 mAh g-1,明显优于纯P25的容量(分别为10和27.8 mAh g-1)。结合X射线近边吸收谱分析表明,所制备复合材料中,Ti O2与3D多孔石墨烯会形成Ti-O-C键,这些化学键的形成利于电池充放电过程中电子的传输,从而使得复合材料的锂电性能有较大的提升。进一步将3D多孔石墨烯与Fe2O3复合,结果显示,在所有温度范围内,复合材料的容量都明显优于纯Fe2O3的容量。以上结果说明3D多孔石墨烯对锂电池阳极材料的储锂性能有较大改进,所制备复合材料适合在0-40 oC区间内使用。所得3D多孔石墨烯可用于制备其它类型锂电池电极复合材料,在航天电源系统中有潜在应用。钠离子电池也是一种重要的电化学储能装置,为了保证其在空间环境中正常工作,开发高性能、高低温稳定的钠电池电极材料非常有必要。但由于Na+具有比Li+更大的离子半径,在充放电过程中所引起的体积效应更大而容易造成电池容量快速衰减。目前碳材料,尤其是石墨烯具有良好的导电性和机械性能可作为稳定的钠离子电池阳极材料。本文利用加热处理三聚氰胺纤维和氧化石墨烯所形成的微米反应单元法,制备了一种由卷曲状结构构筑的具有大孔结构、高比表面积的氮掺杂3D石墨烯。所制备氮掺杂3D石墨烯用于钠离子电池阳极材料时,在室温条件下循环50圈后具有265 mAh g-1的高容量。进一步,当在低温0 oC和高温40oC条件下循环50圈后,其分别具有196和184 m Ah g-1的高容量。结合所得产物的形貌和键合分析显示,所得氮掺杂3D石墨烯所具有的特殊3D结构和氮元素掺杂,可以提供更多的储钠位点并利于电极材料中的电子传输,并最终促进钠电池性能的提高。结果表明所制备氮掺杂3D石墨烯具有优异的储钠性能,其可以在0-40 oC温度范围内使用,为其进一步应用于空间环境提供了借鉴。目前,掺杂石墨烯用于燃料电池氧还原催化剂时存在催化活性位点不确定的问题。本文开发了一种通过只有C、N两种元素的层状化合物(g-C3N4)一步直接转化为氮掺杂石墨烯的方法。通过进一步在800-1000 oC条件下退火处理,可对氮掺杂石墨烯中氮元素种类和含量进行可控调节。所得氮掺杂石墨烯具有高的氧还原性能,其中900 oC退火条件下所得样品的氧还原性能最佳,结合XPS分析可知一定比例的石墨相氮和吡啶氮是氧还原反应的主要催化活性位点。在此基础上,开发了一种利用加热一系列不同摩尔比的二苄基硫醚与三聚氰胺混合物的方法,可控制备了不同掺杂量的硫-氮双掺杂石墨烯。研究了不同硫元素和氮元素含量下样品的氧还原性能,结果显示,900 oC时,前驱体比例为1:6条件下样品的氧还原性能最好。结合样品的结构和键合分析,结果表明在硫-氮双掺杂石墨烯中,吡啶氮和石墨相氮是主要的活性位点,而一定量的硫元素可以起到协同作用,进一步提高氮掺杂石墨烯的氧还原性能。本研究为解决氮掺杂石墨烯在燃料电池氧还原反应中,催化活性位点来源和双掺杂石墨烯中元素的协同效应问题提供了依据,以上结果为开发新型改性石墨烯用于高效料燃料电池阴极催化剂提供了借鉴。
[Abstract]:In order to ensure the normal operation of the various instruments of the spacecraft to support aerospace power systems. The chemical energy is an important part of aerospace power systems, including various ion batteries and fuel cells. In the complex space environment, chemical energy is currently the main research focus is the development of high capacity, high stability of the battery electrode material graphene. As a kind of 2D layered material with large surface area, high conductivity can have potential applications in various electrochemical devices. The preparation of electrode materials for high performance battery as the goal, using modified graphene as the research object, design and development of a variety of control methods of preparing modified graphite graphene, realize high electrochemical performance of electrode materials for lithium battery. In order to alleviate the poor conductivity and volume effect caused in the process of charge and discharge capacity of the attenuation problem, this paper first First, the development of a heating cycle quenching preparation of 3D porous graphene, the product has large surface area and high conductivity. The porous 3D graphene and P25 (Ti O2) composite for lithium ion battery anode, at room temperature after 50 cycles, the capacity of 130 mAh g-1 is 5.2 times that of pure P25 under the same conditions. The capacity of further 50 cycles in high temperature low temperature 0 oC and 40 oC, the capacity of the composite were 91.7 mAh and 89.1 g-1, significantly higher than that of pure P25 capacity (10 and 27.8 mAh g-1). Combined with X ray absorption near edge spectrum analysis shows that the prepared composite material, Ti O2 and 3D porous graphene will form Ti-O-C bond, the formation of such chemical bonds to the electronic transmission of the battery charge and discharge process, so that the electrochemical performance of the composite are obviously improved. The porous 3D graphene and Fe2O3 compound, the In all, in the temperature range, the capacity of the composite is better than pure Fe2O3. The above results showed that the capacity of lithium storage performance of 3D porous graphene anode material for lithium battery is improved, the prepared composite material is suitable for use in the 0-40 oC range. The 3D porous graphene can be used for the preparation of other types lithium battery electrode composite materials have potential applications in aerospace power systems. Sodium ion battery is an important electrochemical storage device, in order to ensure the normal work in the space environment, the development of high performance, it is necessary to high and low temperature stability of sodium battery electrode material. But because the Na+ is greater than the radius of ion Li+, volume effect caused in the process of charging and discharging more easily cause rapid decay. The battery capacity of carbon materials, especially graphene has good conductivity and mechanical properties can be used as a stable The anode materials of sodium ion battery. Using this method micro reaction unit heating treatment of melamine fiber and graphene oxide formed in the preparation of a large pore structure formed by coiled structure, nitrogen doped graphene 3D with high surface area. The preparation of nitrogen doped 3D graphene anode material for sodium ion battery when the cycle of high capacity after 50 cycles with 265 mAh g-1 at room temperature. Further, when 50 cycles at low temperature and high temperature under the condition of 0 oC 40oC, which has high capacity respectively 196 and 184 m Ah g-1. Combined with the morphology and the products of the combination of key analysis showed that the special structure and 3D the nitrogen doped 3D nitrogen doped graphene is, can provide electronic transmission and storage sites for more sodium electrode materials, and ultimately promote the performance of sodium battery increased. The results show that the preparation of nitrogen doped graphene has excellent 3D The storage performance of sodium, can be used in the temperature range of 0-40 oC, which provides the reference for its further application in the space environment at present, the doped graphene used in the catalytic site of the uncertain problems of the fuel cell oxygen reduction catalyst. This paper developed a by only C, layered N two elements (g-C3N4) method directly into nitrogen doped graphene step. By further annealing in the condition of 800-1000 oC, can be controlled on the nitrogen nitrogen doped graphene. The type and content of nitrogen doped graphene has high oxygen reduction performance, which obtained 900 oC annealing conditions for oxygen reduction performance according to XPS analysis, a certain proportion of graphite nitrogen and pyridine nitrogen is the main catalytic site of oxygen reduction reaction. On this basis, the development of a heating using a series of different molar ratio of two The method of dibenzyl sulfide and melamine mixtures, can be controlled by different doping amount of sulfur nitrogen doped graphene. The effects of oxygen in different samples of sulfur and nitrogen content reduction performance, results showed that 900 oC, the proportion of oxygen precursor samples under the condition of 1:6 reduction combined with structural performance is the best. Key and sample analysis, the results show that the sulfur nitrogen doped graphene, pyridine nitrogen and graphite nitrogen are the main active sites, and a certain amount of elemental sulfur can play a synergistic effect, and further improve the nitrogen doped graphene oxygen reduction performance. This research is to solve the nitrogen doped graphene in fuel cell oxygen reduction reaction, provides the basis for the synergy between elements of catalytic active sites source and double doped in graphene, the above results for the development of new modified graphene cathode catalyst used for efficient fuel cell provided by Kam.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ127.11;V442

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