本文選題：多孔石墨烯 + 碳納米管　； 參考：《中國石油大學(北京)》2016年博士論文

【摘要】：近年來,人們對清潔無污染的新型能源越來越關(guān)注。鋰離子電池作為新能源的一種,以其高的能量密度、長的循環(huán)壽命及無記憶效應(yīng)等優(yōu)點被廣泛應(yīng)用于各種便攜式電子設(shè)備,如手機、筆記本電腦和相機等。同時,鋰離子電池在電動汽車領(lǐng)域也表現(xiàn)出了廣闊的應(yīng)用前景,使得具有高能量密度和高功率密度的鋰離子電池成為各國競相開發(fā)的熱點。電極材料是決定鋰離子電池性能的重要因素之一。在負極材料方面,目前商業(yè)化的負極材料主要為石墨,其理論比容量只有372 m Ah g~(-1),遠遠不能滿足電動設(shè)備的實際需求。因此,設(shè)計和制備高性能的鋰離子電池負極材料具有重要的戰(zhàn)略意義。石墨烯作為一種新型的碳材料,因其具有超大的比表面積和超高的導電性等優(yōu)異的性質(zhì),在能源、材料和電化學等領(lǐng)域都有很大的應(yīng)用前景。因此,本文以石墨烯基材料為研究對象,以提高鋰離子電池的能量密度、功率密度及循環(huán)壽命為目的,設(shè)計和制備了一系列高性能的石墨烯基鋰離子電池負極材料。具體內(nèi)容如下:(1)采用化學氣相沉積法,調(diào)控生長制備了具有大比表面積(1620 m g)的多孔石墨烯材料。多孔石墨烯的多孔結(jié)構(gòu)和超高的導電性使其實現(xiàn)了高效的鋰離子和電子傳輸與反應(yīng)。因此,多孔石墨烯表現(xiàn)出優(yōu)異的循環(huán)性能和倍率性能。在電流密度150 m A g~(-1)下循環(huán)50次后,多孔石墨烯的充電比容量從823 m Ah g~(-1)提高到1247 m Ah g~(-1)(提高了34%);在電流密度1000 m A g~(-1)下的充電比容量仍高達455 m Ah g~(-1)。(2)采用化學氣相沉積法,制備了具有三維結(jié)構(gòu)的碳納米管-多孔石墨烯復(fù)合材料。多孔石墨烯的存在有效地抑制了碳納米管的團聚,同時該復(fù)合材料中Fe3C納米顆粒的存在,使其具有了超順磁性,可以應(yīng)用于磁性藥物載體等多個領(lǐng)域。和多孔石墨烯材料相比,碳納米管-多孔石墨烯復(fù)合材料具有更豐富的多孔結(jié)構(gòu),但是由于碳納米管的存在,使其比表面積要比多孔石墨烯小,所以不能提供更多的儲鋰位點,因此其儲鋰性能不如多孔石墨烯材料。(3)多孔石墨烯材料表現(xiàn)出了優(yōu)異的電化學性能,但其超大的比表面積使其首次不可逆容量比較大,因此采用液相沉積法調(diào)控制備了Co3O4-多孔石墨烯復(fù)合材料。Co3O4納米顆粒一方面具有高的理論比容量(890 m Ah g~(-1)),另一方面可以有效地防止多孔石墨烯的堆積和聚并,同時Co3O4納米顆�？梢郧度氲蕉嗫资┑目捉Y(jié)構(gòu)中,降低了復(fù)合材料的比表面積,從而有效地降低了不可逆容量的產(chǎn)生。多孔石墨烯一方面可以緩解Co3O4納米顆粒充放電過程中體積的變化,另一方面其三維多孔網(wǎng)狀結(jié)構(gòu)加速了鋰離子的傳輸,同時其本身是電子的優(yōu)良導體,加速了電子傳輸。因此,Co3O4-多孔石墨烯復(fù)合材料表現(xiàn)出高的質(zhì)量比容量(單位質(zhì)量的活性物質(zhì)的充電容量)和體積比容量(單位體積的活性物質(zhì)的充電容量)。在電流密度150 m A g~(-1)下循環(huán)50次后,70%Co-PGN復(fù)合材料(復(fù)合材料中Co3O4的質(zhì)量分數(shù)為70%)的質(zhì)量比容量由1336 m Ah g~(-1)上升到1439 m Ah g~(-1);當電流密度上升到1000 m A g~(-1)時,70%Co-PGN復(fù)合材料相應(yīng)的質(zhì)量比容量仍然高達1072m Ah g~(-1)。同時,70%Co-PGN復(fù)合材料具有高的體積比容量(在電流密度50和1000m A g~(-1)下,70%Co-PGN復(fù)合材料的體積比容量分別為1993和1678 m Ah cm-3,遠高于多孔石墨烯的體積比容量)。(4)采用液相沉積法制備了具有核@孔@殼結(jié)構(gòu)的Fe_2O_3-多孔石墨烯復(fù)合材料。不同于Co3O4-多孔石墨烯復(fù)合結(jié)構(gòu),在該復(fù)合結(jié)構(gòu)中,Fe_2O_3納米顆粒是通過改變多孔石墨烯的表面結(jié)構(gòu)來提高復(fù)合材料的電化學儲能性能。Fe_2O_3納米顆�？梢源呋纸鈴�(fù)合材料表面形成的SEI膜,從而提高其電化學性能。因此,Fe_2O_3-多孔石墨烯復(fù)合材料表現(xiàn)出優(yōu)異的循環(huán)性能和倍率性能。在電流密度150 m A g~(-1)下循環(huán)50次后,10%Fe-PGN復(fù)合材料(復(fù)合材料中Fe_2O_3的質(zhì)量分數(shù)為10%)的充電比容量由1289 m Ah g~(-1)上升到1567 m Ah g~(-1);在電流密度1000 m A g~(-1)下循環(huán)100次后,10%Fe-PGN復(fù)合材料的充電比容量由814 m Ah g~(-1)上升到883 mAh g~(-1)。
[Abstract]:In recent years, people have paid more and more attention to clean and non polluting new energy sources. As a new energy source, lithium ion batteries have been widely used in all kinds of portable electronic devices, such as mobile phones, notebook electroencephalograph and cameras, etc., with their high energy density, long cycle life and memory free effect. The domain also shows broad application prospects, making lithium ion batteries with high energy density and high power density become the hot spots in the development of various countries. Electrode material is one of the important factors to determine the performance of lithium ion batteries. In the negative electrode material, the commercialized negative material is mainly graphite, its theoretical specific capacity is only 372 m. Ah g~ (-1) can not meet the actual demand of electric equipment. Therefore, the design and preparation of high performance anode materials for lithium ion batteries is of great strategic significance. As a new type of carbon material, graphene has excellent properties, such as high specific surface area and ultra-high conductivity, in the fields of energy, materials and electrochemistry. In order to improve the energy density, power density and cycle life of lithium ion batteries, a series of high performance graphite anode materials for lithium ion batteries are designed and prepared in this paper. The specific contents are as follows: (1) chemical vapor deposition (CVD) is used to regulate and control the growth of the lithium ion battery. Porous graphene material with large specific surface area (1620 m g). Porous graphene's porous structure and ultra-high conductivity make it achieve high efficiency of lithium ion and electron transfer and reaction. Therefore, porous graphene shows excellent cycling performance and multiplying performance. After 50 cycles under the current density of 150 m A g~ (-1), porous graphene The charge specific capacity is increased from 823 m Ah g~ (-1) to 1247 m Ah g~ (-1) (increased by 34%), and the charge specific capacity at 1000 m A g~ (-1) is still up to 455. (2) the carbon nanotube porous graphene composite with three-dimensional structure is prepared by chemical vapor deposition. The presence of porous graphene effectively inhibits carbon The presence of Fe3C nanoparticles in the composite makes it superparamagnetic and can be used in many fields, such as magnetic drug carriers. Compared with the porous graphene material, the carbon nanotube - porous graphene composite has a more abundant porous structure, but the presence of carbon nanotubes makes it more than the surface. The product is smaller than porous graphene, so it can not provide more lithium storage sites, so its lithium storage performance is not as good as porous graphene material. (3) porous graphene exhibits excellent electrochemical performance, but its large specific surface area makes its initial irreversible capacity larger, so Co3O4- multi Kong Shi is controlled by liquid phase deposition. .Co3O4 nanoparticles have high theoretical specific capacity (890 m Ah g~ (-1)) on the one hand, on the other hand, it can effectively prevent the accumulation and accumulation of porous graphene, and Co3O4 nanoparticles can be embedded in the pore structure of porous graphene, reducing the specific surface area of the composite, thus effectively reducing the irreversible capacity. On the one hand, porous graphene can alleviate the volume change in the charge discharge process of Co3O4 nanoparticles, on the other hand, the three-dimensional porous network structure accelerates the transmission of lithium ion. At the same time, it is an excellent conductor of the electron and accelerates the electron transport. Therefore, the Co3O4- polypore graphene composite exhibits high mass ratio capacity. (unit mass active material charging capacity) and volume specific capacity (charge capacity per unit volume of active substance). After 50 cycles under 150 m A g~ (-1) current density, the mass ratio of 70%Co-PGN composites (the mass fraction of Co3O4 in composite materials is 70%) rises from 1336 m Ah g~ (-1) to 1439 m Ah. When up to 1000 m A g~ (-1), the corresponding mass specific capacity of 70%Co-PGN composites is still as high as 1072m Ah g~ (-1). At the same time, the 70%Co-PGN composite has a high volume specific capacity (at the current density of 50 and 1000m A), the volume specific capacity of the composite material is 1993 and 1678, far higher than the volume ratio of the porous graphene. (4) (4) a porous graphene composite with a core @ shell structure is prepared by liquid deposition. Different from the composite structure of Co3O4- porous graphene, the Fe_2O_3 nanoparticles can improve the electrochemical energy storage properties of the composite by changing the surface structure of the porous graphene to improve the electrochemical energy storage properties of.Fe_2O_3 nanoparticles. It can catalyze the decomposition of the SEI film formed on the surface of the composite to improve its electrochemical performance. Therefore, the Fe_2O_3- porous graphene composite exhibits excellent cycling performance and multiplying performance. After 50 cycles under the current density of 150 m A g~ (-1), the specific capacitance of the 10%Fe-PGN composite (the mass fraction of Fe_2O_3 in the composite is 10%) The quantity rises from 1289 m Ah g~ (-1) to 1567 m Ah g~ (-1); after 100 cycles under the current density of 1000 m A g~ (-1), the charge ratio of the composite increases from 814 to 883.
【學位授予單位】：中國石油大學(北京)
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TQ127.11;TB33;TM912

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