高性能石墨烯纤维

发布时间：2018-02-28 19:51

本文关键词： 石墨烯纤维高强度高模量高导电超导　出处：《浙江大学》2017年博士论文　论文类型：学位论文

【摘要】：石墨烯纤维是由石墨烯沿轴向紧密有序排列而成的连续宏观组装材料,是近年来发展起来的一种新型碳质纤维。石墨烯纤维具有高强度、高导电、低密度等特性,已在轻质导线、柔性储能器件等方面展示了广阔的应用前景。然而目前其单丝制备规模较小,力学强度和导电性能远不能满足人们对结构功能一体化的需求,极大地限制了石墨烯纤维的应用与发展。因此提高石墨烯纤维的力学和导电性能,发展宏量化制备技术,已成为石墨烯纤维研究领域的核心问题,这也是推进石墨烯纤维结构功能一体化发展的关键。为此,本论文瞄准石墨烯纤维的高性能化和规模化制备,立足于纤维微纳结构调控及其与宏观性能的关系,开展了系列的研究。主要内容如下:1.提出了“多尺度结构缺陷控制”策略,通过拉伸诱导取向、纤维细旦化、高温热还原等关键技术创新,调控从分子水平跨越到宏观材料尺度的多级结构缺陷,实现了高性能石墨烯纤维的制备,阐明了石墨烯纤维综合性能与多级缺陷结构的关系。石墨烯纤维拉伸强度和模量分别可达2.2 GPa和400 GPa,导电率高达0.8MS/m,并且具有高于铜的熔断电流密度(23GA/m2),是目前石墨烯纤维所到达的最高水平。2.自主设计并搭建了石墨烯纤维束丝示范型生产线,将实验室单丝制备水平推进到100束丝的连续制备水平,建立了完整的从石墨烯液晶到连续湿纺和热处理的石墨烯纤维束丝制备体系,有助于推动石墨烯纤维的工程化发展。3.提出“化学掺杂”策略,制备了电子给体及电子受体掺杂的石墨烯纤维系列,将其导电率提高到金属水平,揭示了掺杂分子通过增加载流子浓度来提升导电率的机理。其中钾掺杂石墨烯纤维的导电率高达22 MS/m,高于镍(15 MS/m),接近铝(35MS/m)。值得一提的是,其比导电率(导电率与密度的比值)约是镍的8倍、铜的2倍,与铝相当。这一优异性能使石墨烯纤维在轻质导线、电动马达、信号传输、能源储存与转化、电磁屏蔽等领域有巨大的应用价值。“化学掺杂”策略也为其他维度石墨烯宏观材料导电性能的升级提供了新思路。4.通过气相插层反应,实现了钙插层柔性超导石墨烯纤维的制备,其超导转变温度为11K,与商用NbTi超导线相当,是宏观碳材料领域首例超导纤维。这种新型轻质超导纤维在未来电力传输、低温物理、航空航天等领域具有良好的应用前景。总之,本论文以石墨烯纤维的高性能化为目标,发展了高强高模石墨烯纤维、高导电石墨烯纤维、超导石墨烯纤维系列,系统的研究了石墨烯纤维结构与性能的关系,为石墨烯纤维的发展起了重要推动作用。
[Abstract]:Graphene fiber is a kind of continuous macroscopical assembly material which is arranged closely and orderly along the axis of graphene. It is a new type of carbon fiber developed in recent years. Graphene fiber has the characteristics of high strength, high conductivity, low density and so on. It has been widely used in light wire, flexible energy storage devices and so on. However, its monofilament is small in scale, and its mechanical strength and conductivity can not meet the needs of structural and functional integration. Therefore, improving the mechanical and conductive properties of graphene fibers and developing macroquantitative preparation technology have become the core problems in the research field of graphene fibers. This is also the key to promote the development of graphene fiber structure and function integration. Therefore, this paper aims at the high performance and scale preparation of graphene fiber, based on the control of fiber micro and nano structure and its relationship with macroscopical properties. A series of studies have been carried out. The main contents are as follows: 1. The strategy of "multi-scale structural defect control" is put forward, through the key technology innovation, such as tensile induced orientation, fine denier of fiber, high temperature thermal reduction, etc. The preparation of high performance graphene fiber was realized by regulating the multilevel structural defects from molecular level to macroscopic material scale. The relationship between the comprehensive properties of graphene fiber and the multistage defect structure is clarified. The tensile strength and modulus of graphene fiber can reach 2.2 GPa and 400GPA, respectively. The conductivity of graphene fiber is as high as 0.8ms / m, and it has a melting current density of 23GA / m2, which is higher than that of copper. The highest level reached by allene fibers. 2. A demonstration production line of graphene fiber bundles was designed and built. The preparation system of graphene fiber bundles from graphene liquid crystal to continuous wet spinning and heat treatment was established by pushing the preparation level of laboratory monofilament to the continuous preparation level of 100 bundles. It is helpful to promote the engineering development of graphene fiber. 3. A "chemical doping" strategy is proposed to prepare the series of graphene fibers doped with electron donor and electron acceptor. The conductivity of graphene fibers is increased to metal level. The mechanism of increasing the conductivity of doped molecules by increasing carrier concentration is revealed, in which the conductivity of potassium doped graphene fibers is as high as 22 Ms / m, which is higher than that of Nickel-doped graphene fibers at 15 Ms / m ~ (-1), and is close to that of Al ~ (35) M / m ~ (-1). It is worth mentioning that, Its specific conductivity (the ratio of conductivity to density) is about 8 times that of nickel and 2 times that of copper, and is comparable to aluminum. This excellent performance makes graphene fibers in light conductors, electric motors, signal transmissions, energy storage and conversion. Electromagnetic shielding and other fields have great application value. The "chemical doping" strategy also provides a new way to upgrade the conductivity of other dimension graphene macroscopical materials. 4. Through gas phase intercalation reaction, The preparation of calcium intercalated flexible superconducting graphene fiber is realized. The superconducting transition temperature is 11K, which is the same as commercial NbTi superconductor. It is the first superconducting fiber in the field of macroscopic carbon materials. In this paper, the high strength and high modulus graphene fiber, high conductive graphene fiber, superconducting graphene fiber series have been developed with the aim of high performance of graphene fiber. The relationship between structure and properties of graphene fibers is studied systematically, which plays an important role in the development of graphene fibers.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ342.74

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