【摘要】：低維材料，特別是低維碳納米材料，一直是材料學(xué)的研究熱點(diǎn)。自從2004年實(shí)驗(yàn)上成功制備以來(lái)，石墨烯（Graphene）這種由碳原子以sp2雜化軌道組成的六角型蜂巢狀二維結(jié)構(gòu)，憑借其獨(dú)特的性能在碳材料領(lǐng)域備受關(guān)注。繼石墨烯之后，實(shí)驗(yàn)上分別制備出石墨炔（Graphdiyne）等新的碳同素異形體。與石墨烯不同，石墨炔是以sp和sp2雜化形成的二維結(jié)構(gòu)，擁有更豐富的碳化學(xué)鍵，具有與很多石墨烯截然不同的性質(zhì)，甚至在某些性能上有望超越石墨烯，比如其有天然的孔結(jié)構(gòu)、熱導(dǎo)率較低等特性。在傳統(tǒng)能源短缺、新能源亟待開(kāi)發(fā)的大背景下，石墨炔體系具有良好的應(yīng)用前景。因此本文主要針對(duì)其孔結(jié)構(gòu)和低熱導(dǎo)特性，研究了石墨炔體系在鋰電池材料和熱電材料等能源領(lǐng)域的性能。取得的成果如下： （1）石墨炔是以sp2和sp兩種雜化態(tài)形成的二維碳同素異形體。通過(guò)改變碳六元環(huán)之間炔鍵的數(shù)目，可以改變碳鏈的長(zhǎng)度，進(jìn)而得到不同代數(shù)的石墨炔。通過(guò)基于密度泛函理論的第一性原理計(jì)算方法，我們研究了石墨炔體系的儲(chǔ)鋰性能，結(jié)果表明石墨炔體系是一種理想的儲(chǔ)鋰材料，鋰原子通過(guò)向襯底轉(zhuǎn)移電荷而帶正電，彼此之間的庫(kù)侖排斥作用避免了鋰原子的團(tuán)簇化。通過(guò)比較石墨一炔到石墨五炔的儲(chǔ)鋰性能，發(fā)現(xiàn)對(duì)于石墨炔體系，并不是炔鍵數(shù)目越多，原子密度越低，結(jié)構(gòu)對(duì)應(yīng)的儲(chǔ)鋰性能就會(huì)越好，還需考慮炔鍵的增多對(duì)結(jié)構(gòu)穩(wěn)定性的影響。在保證石墨炔類結(jié)構(gòu)穩(wěn)定的前提下，石墨二炔和石墨五炔可以達(dá)到LiC3的最大儲(chǔ)鋰量，對(duì)應(yīng)Li的平均吸附能分別為-2.00和-2.05eV。 （2）通過(guò)將石墨炔納米帶沿固定軸卷曲可以得到石墨炔納米管（GNT）這種一維材料，，并且改變碳六元環(huán)之間炔鍵的數(shù)目，可得到不同代數(shù)的石墨炔納米管，記作GNT-n。利用非平衡分子動(dòng)力學(xué)模擬，我們對(duì)GNT體系的熱導(dǎo)性能進(jìn)行了研究，討論了代數(shù)n、直徑d和長(zhǎng)度L等變量對(duì)體系熱導(dǎo)率的影響。計(jì)算結(jié)果表明隨代數(shù)n增加，熱導(dǎo)率降低并遵循~n0.57關(guān)系。直徑變化對(duì)體系熱導(dǎo)率的影響較弱，當(dāng)d5nm時(shí)遵循~d0.03關(guān)系。隨GNT體系長(zhǎng)度的增加，結(jié)構(gòu)熱導(dǎo)率也增加并符合~L關(guān)系，且關(guān)系曲線存在拐點(diǎn)，拐點(diǎn)兩邊對(duì)應(yīng)不同的指數(shù)。通過(guò)推算我們得到長(zhǎng)度為2.6μm的GNT-n（n=1～5）的熱導(dǎo)率分別為92.4，43.6，30.4，27.4和23.0W/(m.K)，與相同長(zhǎng)度的CNT（λ=2820.6W/(m.K)）相比熱導(dǎo)率小兩個(gè)數(shù)量級(jí)，在二者擁有相同或相近的電導(dǎo)率情況下，更低的熱導(dǎo)率使得GNT相對(duì)于CNT擁有更高的熱電品質(zhì)因子，有望在將來(lái)成為優(yōu)異的熱電材料。
[Abstract]:Low-dimensional materials, especially low-dimensional carbon nanomaterials, have been the focus of materials research. Since its successful preparation in 2004, graphene (Graphene), a hexagonal honeycomb structure composed of carbon atoms and sp2 hybrid orbitals, has attracted much attention in the field of carbon materials due to its unique properties. After graphene, new carbon isomorphs such as graphite acetylene (Graphdiyne) were prepared. Unlike graphene, graphite acetylene is a two-dimensional structure formed by sp and sp2 hybrids. It has a richer carbon chemical bond and has distinct properties from many graphene, and is expected to surpass graphene in some properties. For example, it has natural pore structure, low thermal conductivity and other characteristics. Under the background of the shortage of traditional energy and the urgent development of new energy, graphite acetylene system has a good application prospect. Therefore, based on the pore structure and low thermal conductivity, the performance of graphite system in lithium battery materials and thermoelectric materials is studied in this paper. The results obtained are as follows: (1) Graphite acetylene is a two-dimensional carbon isomorphism formed in two hybrid states of sp2 and sp. The length of carbon chain can be changed by changing the number of acetylene bonds between six carbon rings, and then different algebraic graphite acetylene can be obtained. Based on the density functional theory (DFT), we have studied the lithium storage properties of graphite acetylene system. The results show that graphite acetylene system is an ideal lithium storage material. Lithium atoms are positively charged by transfer of charge to the substrate. The Coulomb repulsion between each other avoids the cluster of lithium atoms. By comparing the lithium-storage properties of graphite-acetylene to graphite-pentylene, it is found that the higher the number of acetylene bonds, the lower the atomic density, and the better the lithium-storage performance of the corresponding structure. It is also necessary to consider the influence of the increase of acetylene bond on the stability of the structure. On the premise of ensuring the stability of graphite acetylene structure, graphite diacetylene and graphite pentylene can reach the maximum lithium storage capacity of LiC3. The average adsorption energies corresponding to Li are -2.00 and -2.05 EV respectively. (2) by curling graphene nanobelts along a fixed axis, one-dimensional materials such as (GNT) can be obtained, and the number of acetylene bonds between carbon six-member rings can be changed. Graphite nanotubes of different algebras can be obtained, denoted as GNT-n. The thermal conductivity of GNT system is studied by using nonequilibrium molecular dynamics simulation. The effects of algebraic variables n, diameter d and length L on the thermal conductivity of the system are discussed. The results show that with the increase of algebra n, the thermal conductivity decreases and follows the n0.57 relation. The influence of diameter change on the thermal conductivity of the system is weak, and the relationship between the thermal conductivity and the thermal conductivity is observed when d5nm is observed. With the increase of the length of GNT system, the thermal conductivity of the structure also increases and accords with the L relation, and the curve has inflection point, and the inflection point corresponds to different exponents on both sides of the inflection point. The thermal conductivities of 2.6 渭 m long GNT-n (ng1 / 5) are 92. 4 渭 m, 43. 6 and 30. 440. 4 and 23.0W/ (m. K), respectively, which are two orders of magnitude smaller than that of CNT of the same length (位 2 820. 6 W / (m 路K). Under the condition of the same or similar electrical conductivity, the thermal conductivity of CNT (位 2 820. 6 W / (m. K) is lower than that of CNT (位 2 820. 6 W / (m 路K). Lower thermal conductivity makes GNT have a higher thermoelectric quality factor than CNT and is expected to be an excellent thermoelectric material in the future.
【學(xué)位授予單位】：華東交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.1;TQ127.11

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 趙晗;周麗娜;魏東山;周新建;史浩飛;;石墨炔類結(jié)構(gòu)儲(chǔ)鋰性能的第一性原理研究[J];高等學(xué)校化學(xué)學(xué)報(bào);2014年08期

本文編號(hào)：2210553