本文選題：超順排碳納米管 + 復(fù)合宏觀體��； 參考：《清華大學(xué)》2015年博士論文

【摘要】：碳納米管作為一種一維納米管狀結(jié)構(gòu),具有優(yōu)異的電學(xué)、力學(xué)與熱學(xué)性能,因此具有十分廣闊的應(yīng)用前景。然而要滿足宏觀尺度上的應(yīng)用要求,常常需要將微納米量級(jí)的碳納米管與復(fù)合材料組裝成宏觀可操作的結(jié)構(gòu)。超順排碳納米管(SACNT)由于相互作用力很強(qiáng),可以從陣列上抽出連續(xù)的長(zhǎng)線和薄膜等宏觀體,且已有諸多應(yīng)用實(shí)例。在本論文中,將進(jìn)一步設(shè)計(jì)和構(gòu)筑新型的超順排碳納米管復(fù)合宏觀結(jié)構(gòu),并研究其性能與應(yīng)用。其中包括:1)通過(guò)超聲共沉降法(即SACNT與復(fù)合顆粒在共同超聲分散后會(huì)自發(fā)地快速共同沉降)獲得了“巴基紙”型的二維無(wú)序復(fù)合膜。該結(jié)構(gòu)中的超順排碳納米管添加量雖少(少至1 wt%),卻能以無(wú)序連續(xù)網(wǎng)絡(luò)的形式均勻分散于整個(gè)復(fù)合膜中,并將復(fù)合顆粒包裹于該網(wǎng)絡(luò)之中,獨(dú)立起到了導(dǎo)電和力學(xué)支撐網(wǎng)絡(luò)的作用。所以,該結(jié)構(gòu)具有以下優(yōu)點(diǎn):無(wú)需粘結(jié)劑,分散均勻,導(dǎo)電性優(yōu)異和柔性等。若將復(fù)合顆粒選為商業(yè)化的鈷酸鋰,則該復(fù)合膜可以作為鋰離子電池正極,且具有優(yōu)異的循環(huán)穩(wěn)定性,倍率性能(2C倍率下的比容量為134 mAh/g)和更高的能量密度(比傳統(tǒng)電極材料高出20%)。除此外,超聲共沉降法還具有應(yīng)用范圍廣泛、過(guò)程簡(jiǎn)單快速(共沉降過(guò)程僅需1 min)、易于控制和實(shí)現(xiàn)大規(guī)模生產(chǎn)等優(yōu)點(diǎn)。而實(shí)現(xiàn)該方法即超聲共沉降現(xiàn)象的關(guān)鍵點(diǎn)在于:碳納米管間的相互作用力足夠強(qiáng),能夠在超聲分散后快速地自發(fā)形成完整連續(xù)網(wǎng)絡(luò),目前僅發(fā)現(xiàn)超順排碳納米管滿足此要求。2)通過(guò)超聲-自組裝方法獲得的“海綿型”的三維結(jié)構(gòu)。該結(jié)構(gòu)不僅具有輕質(zhì)(1.3~40 mg/cm3)、疏松多孔(孔隙率大于99%)、導(dǎo)電、自支撐等特點(diǎn),還有制備工藝簡(jiǎn)單可控、無(wú)需外在粘結(jié)劑、僅靠碳納米管間很強(qiáng)的相互作用力自發(fā)組裝成三維海綿等特點(diǎn)。通過(guò)在該海綿表面包覆一層小于2 nm的完整包覆碳層,能使其成為完全的彈性體。該海綿還具有疏水的特性,在空氣中以550oC氧化改性可以使其變?yōu)橛H水性。這種基于超順排碳納米管及改性的海綿具有廣泛的應(yīng)用,包括能源、生物、吸附、催化、模板應(yīng)用等等。其中,將沉碳改性的海綿作為鋰離子電池負(fù)極,還表現(xiàn)出了極優(yōu)異的循環(huán)性能和倍率性能(50C倍率下相對(duì)于0.1C的容量保持率仍有58%),在高倍率的超長(zhǎng)循環(huán)下(如1500圈)還具有比容量不斷上升的特性。
[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).
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ127.11;TB383.1

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