超顺排碳纳米管复合宏观体的构筑、性能与应用

发布时间：2018-07-06 08:08

本文选题：超顺排碳纳米管 + 复合宏观体　；参考：《清华大学》2015年博士论文

【摘要】：碳纳米管作为一种一维纳米管状结构,具有优异的电学、力学与热学性能,因此具有十分广阔的应用前景。然而要满足宏观尺度上的应用要求,常常需要将微纳米量级的碳纳米管与复合材料组装成宏观可操作的结构。超顺排碳纳米管(SACNT)由于相互作用力很强,可以从阵列上抽出连续的长线和薄膜等宏观体,且已有诸多应用实例。在本论文中,将进一步设计和构筑新型的超顺排碳纳米管复合宏观结构,并研究其性能与应用。其中包括:1)通过超声共沉降法(即SACNT与复合颗粒在共同超声分散后会自发地快速共同沉降)获得了“巴基纸”型的二维无序复合膜。该结构中的超顺排碳纳米管添加量虽少(少至1 wt%),却能以无序连续网络的形式均匀分散于整个复合膜中,并将复合颗粒包裹于该网络之中,独立起到了导电和力学支撑网络的作用。所以,该结构具有以下优点:无需粘结剂,分散均匀,导电性优异和柔性等。若将复合颗粒选为商业化的钴酸锂,则该复合膜可以作为锂离子电池正极,且具有优异的循环稳定性,倍率性能(2C倍率下的比容量为134 mAh/g)和更高的能量密度(比传统电极材料高出20%)。除此外,超声共沉降法还具有应用范围广泛、过程简单快速(共沉降过程仅需1 min)、易于控制和实现大规模生产等优点。而实现该方法即超声共沉降现象的关键点在于:碳纳米管间的相互作用力足够强,能够在超声分散后快速地自发形成完整连续网络,目前仅发现超顺排碳纳米管满足此要求。2)通过超声-自组装方法获得的“海绵型”的三维结构。该结构不仅具有轻质(1.3~40 mg/cm3)、疏松多孔(孔隙率大于99%)、导电、自支撑等特点,还有制备工艺简单可控、无需外在粘结剂、仅靠碳纳米管间很强的相互作用力自发组装成三维海绵等特点。通过在该海绵表面包覆一层小于2 nm的完整包覆碳层,能使其成为完全的弹性体。该海绵还具有疏水的特性,在空气中以550oC氧化改性可以使其变为亲水性。这种基于超顺排碳纳米管及改性的海绵具有广泛的应用,包括能源、生物、吸附、催化、模板应用等等。其中,将沉碳改性的海绵作为锂离子电池负极,还表现出了极优异的循环性能和倍率性能(50C倍率下相对于0.1C的容量保持率仍有58%),在高倍率的超长循环下(如1500圈)还具有比容量不断上升的特性。
[Abstract]:As a one-dimensional nanotube structure, carbon nanotubes have excellent electrical, mechanical and thermal properties, so they have a wide application prospect. However, in order to meet the requirements of macro-scale applications, it is often necessary to assemble micro-nanotubes and composites into macroscopically operable structures. Super-cis-emission carbon nanotubes (SACNT) have been widely used in many applications because of their strong interaction and the ability to extract continuous long wires and thin films from the array. In this thesis, a new composite macrostructure of supercis carbon nanotubes will be designed and constructed, and its properties and applications will be studied. Among them, the "base-paper" two-dimensional disordered composite film was obtained by the ultrasonic co-deposition method (i.e. SACNT and composite particles will spontaneously and rapidly settle together after ultrasonic dispersion). Although the amount of supercis carbon nanotubes added in the structure is as small as 1 wt%, it can be uniformly dispersed in the whole composite film in the form of a disordered continuous network, and the composite particles are encapsulated in the network. Independent plays the role of conductive and mechanical support network. Therefore, the structure has the following advantages: no binder, uniform dispersion, excellent conductivity and flexibility. If the composite particles are selected as commercial lithium cobaltate, the composite film can be used as the cathode of lithium ion battery and has excellent cycling stability. The ratio performance (specific capacity at 2C rate is 134 mAh/g) and higher energy density (20% higher than traditional electrode material). In addition, the ultrasonic co-sedimentation method also has the advantages of wide application, simple and fast process (only 1 min), is required for easy control and realization of large-scale production). The key point to realize this method is that the interaction between carbon nanotubes is strong enough to form a complete continuous network spontaneously after ultrasonic dispersion. At present, only supercis carbon nanotubes meet this requirement. 2) the "sponge" 3D structure obtained by ultrasonic-self-assembly method. The structure not only has the characteristics of light weight (1.3 ~ 40 mg/cm3), loose and porous (porosity > 99%), conductive, self-supporting, etc., but also has the advantages of simple and controllable preparation process without external binder. Only by the strong interaction between carbon nanotubes self-assembled into three-dimensional sponge and other characteristics. By coating a carbon layer less than 2 nm on the surface of the sponge, it can be made into a complete elastomer. The sponge also has hydrophobic properties and can be modified to hydrophilicity by oxidation with 550 OC in air. The supercis carbon nanotubes and modified sponges have a wide range of applications, including energy, biology, adsorption, catalysis, template applications and so on. Among them, the sponge modified by carbon deposition is used as the negative electrode of the lithium-ion battery. It also shows excellent cycle performance and rate performance (the capacity retention rate of 50C is still 58% relative to 0.1C), and the specific capacity is increasing under the ultra-long cycle with high rate (such as 1500 cycles).
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ127.11;TB383.1

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