本文選題：鋰離子電池 + 負極材料��； 參考：《青島科技大學(xué)》2017年碩士論文

【摘要】：鋰離子電池因其具有能量密度高、循環(huán)壽命長和對環(huán)境友好等優(yōu)點,被認為是最具發(fā)展前景的電能存儲技術(shù)之一。目前商業(yè)化鋰離子電池中普遍采用石墨類型的碳負極材料,但其理論容量低、能量密度小、安全隱患多等缺點已不能滿足人們對高性能、氋安全性的鋰離子電池的需求。因此,研究和開發(fā)新型的、具有高性能表現(xiàn)的鋰離子電池負極材料具有極其重要的現(xiàn)實意義。過渡金屬氧(硫)化物在眾多備選材料中具有理論容量高、資源豐富、環(huán)境友好、安全性高等優(yōu)點得到了廣泛關(guān)注。然而它們也存在著導(dǎo)電性差、首次庫倫效率低和充放電過程中體積變化大導(dǎo)致循環(huán)穩(wěn)定性差的問題。此外,以二硫化鉬為代表的過渡金屬硫化物表現(xiàn)出了優(yōu)異的電催化析氫性能。但二硫化鉬的催化活性位點數(shù)量較少且是一種半導(dǎo)體材料,導(dǎo)電性較差,因此與鉑族貴金屬相比性能仍有很大差距。石墨烯具有電子遷移率高、比表面積大、柔韌性好等獨特的性質(zhì),在納米電子器件、電化學(xué)儲能和能源轉(zhuǎn)換等領(lǐng)域具有廣泛的應(yīng)用。本論文針對過渡金屬氧(硫)化物的特點和存在的缺陷,結(jié)合石墨烯材料的優(yōu)點,分別從材料納米化、電極結(jié)構(gòu)、形貌調(diào)控等方面對其進行了研究以提高其電化學(xué)儲鋰和電催化析氫性能,具體的研究工作如下:1.首次設(shè)計并制備了夾層石墨烯紙@Fe_3O_4納米棒陣列@石墨烯(GPFG)復(fù)合材料,作為高性能鋰離子電池的集成電極。Fe_3O_4納米棒陣列直接生長在導(dǎo)電的石墨烯紙上,確保了快速反應(yīng)動力學(xué)與高可逆性。石墨烯包覆層不僅加速電子轉(zhuǎn)移,還可以緩沖體積變化。因此,電極表現(xiàn)出相當(dāng)大而穩(wěn)定的儲鋰容量,良好的倍率性能和長久的循環(huán)壽命。遺憾的是,石墨烯包覆層只是物理沉積在納米陣列表面,機械穩(wěn)定性較脆弱,在電極充放電過程中容易破碎。在此基礎(chǔ)上,又利用碳膜作為包覆層來制備新穎的夾心狀石墨烯紙@Fe_3O_4納米棒陣列@碳(GFC)自支撐電極。碳膜是通過沉積的聚苯胺(PANI)薄膜原位轉(zhuǎn)化得到,因而具有良好的機械穩(wěn)定性,可很好地包裹納米棒陣列并有效抑制破碎的納米棒進入電解液。正是由于此種獨特的復(fù)合結(jié)構(gòu),此類具有內(nèi)部陣列結(jié)構(gòu)的夾心狀電極展現(xiàn)出出色的電化學(xué)儲鋰性能,尤其是在高電流密度(在2 A g-1循環(huán)1000圈后852 mA g-1)下有著高容量,穩(wěn)定,持久的循環(huán)性能,使其有望作為一種高性能集成電極。2.利用多面體CoSn(OH)_6作為前驅(qū)體,構(gòu)造了石墨烯包裹SnO_2-Co_3O_4立方體(G/SnO_2-Co_3O_4)的柔性集成電極,并用于鋰離子電池。復(fù)合電極組分的合理選擇,材料獨特的多面體納米結(jié)構(gòu)和適當(dāng)?shù)膹?fù)合材料構(gòu)建方法成功產(chǎn)生了協(xié)同儲鋰效應(yīng),實現(xiàn)了SnO_2和石墨烯界面儲鋰的部分可逆轉(zhuǎn)換,使電極在100 mA g-1下循環(huán)100圈后可逆容量仍高達1665 mAh g-1。在1 A g-1大電流密度下,電極依然保持高容量、穩(wěn)定的循環(huán)性能和長效的循環(huán)壽命(循環(huán)1000圈后容量為1208 mAh g-1)。更重要的是,本實驗制備的自支撐電極在反復(fù)300次電化學(xué)循環(huán)后能很好地保持它的柔韌性,這使其有望作為高效而又穩(wěn)定的柔性鋰離子電池電極材料之一。3.利用蒸發(fā)誘導(dǎo)自組裝的方法首次合成了用作鋰離子電池負極材料的介孔正八面體Fe Co_2O_4。尖晶石型混合過渡金屬氧化物中部分金屬被替代可以提高其儲鋰性能。各向異性的正八面體結(jié)構(gòu)可以保持結(jié)構(gòu)的穩(wěn)定性,提高循環(huán)性能。介孔結(jié)構(gòu)能夠縮短電荷傳輸路徑,促進電解液的流動和浸潤,提供更多的表面積吸附鋰離子,還可以提供更多空間緩沖體積變化。擁有多組分的協(xié)同效應(yīng),穩(wěn)定的正八面體結(jié)構(gòu)和介孔結(jié)構(gòu),使得樣品表現(xiàn)出良好的電化學(xué)性能,包括高容量,快速充放電和穩(wěn)定的循環(huán)性能(1 A g-1循環(huán)200圈后為1101 mAh g-1),以及曾報道的Fe Co_2O_4最好的倍率性能(在10 A g-1下為518 m Ah g-1)。4.通過水熱法合理設(shè)計并成功制備了石墨烯量子點摻雜的MoS_2納米片(GQDs/MoS_2),并利用XRD,SEM,TEM和拉曼技術(shù)等對其結(jié)構(gòu)進行表征。摻雜GQDs擴大了MoS_2的層間距,加速電化學(xué)動力學(xué),并緩沖體積效應(yīng),有助于同時增強MoS_2在結(jié)構(gòu)和組成上的優(yōu)勢,提高儲鋰性能。當(dāng)作為一種鋰離子電池負極材料時,GQDs/MoS_2表現(xiàn)出高容量、良好的循環(huán)性能和倍率性能。摻雜到MoS_2中的GQDs在納米片邊緣和基底平面形成大量缺陷,這是其提高催化活性和電導(dǎo)率的關(guān)鍵因素。正因為如此,樣品對電化學(xué)析氫反應(yīng)的催化性能有著顯著提高,其中包括較大的陰極電流(在200 mV的低過電位時為10 mA cm-2和在300mV的低過電位時為74 mA cm-2)和較低的起始電位(140 mV)。
[Abstract]:Lithium ion batteries are considered to be one of the most promising energy storage technologies because of their high energy density, long cycle life and friendly environment. At present, graphite type carbon negative materials are widely used in commercial lithium ion batteries, but their shortcomings such as low theoretical capacity, small energy density and many hidden dangers are not satisfied. Therefore, it is of great practical significance to study and develop a new type of lithium ion battery anode material with high performance. The transition metal oxygen (sulfur) compounds have the advantages of high theoretical capacity, rich resources, friendly environment and high safety in many alternative materials. There is a wide range of concerns. However, they also have poor conductivity, the first Kulun low efficiency and the large volume change in the charge discharge process lead to poor circulation stability. In addition, the transition metal sulfide represented by molybdenum disulfide shows excellent electrocatalytic hydrogen evolution performance. But the number of catalytic active sites of two molybdenum sulfide is less and is less than that of molybdenum sulfide. A semiconductor material has poor conductivity, so there is still a big gap in performance compared with platinum group precious metals. Graphene has a unique property, such as high electron mobility, large specific surface area, good flexibility and so on. It is widely used in the fields of nanoscale electronic devices, electrochemical energy storage and energy conversion. The characteristics and existing defects, combined with the advantages of graphene materials, have been studied in terms of material nanoscale, electrode structure, morphology control, etc. to improve their electrochemical lithium storage and electrocatalytic hydrogen evolution performance. The specific research work is as follows: 1. the first design and preparation of sandwich graphene @Fe_3O_4 nanorod array @ graphene (GP) FG) composites, as an integrated electrode.Fe_3O_4 nanorod array of high performance lithium ion batteries, grow directly on the conductive graphene paper, which ensures fast reaction kinetics and high reversibility. The graphene coating not only accelerates electron transfer, but also can buffer volume change. Therefore, the electrode shows considerable and stable lithium storage capacity. It is regrettable that the graphene coating is only physically deposited on the surface of nanowire arrays, and the mechanical stability is fragile and easily broken during the charge discharge process of the electrode. On this basis, the carbon film is used as a coating to prepare a novel sandwich like graphene paper @Fe_3O_4 nanorod array @ carbon (GFC). Self supporting electrode. The carbon film is obtained by in situ transformation of the deposited polyaniline (PANI) film, thus having good mechanical stability. It can well wrap the nanorod array and effectively suppress the broken nanorods into the electrolyte. It is because of this unique composite structure that the sandwich electrodes with internal array structure show out. The electrochemical lithium-ion storage properties of color, especially at high current density (2 A g-1 cycle 1000 cycles after 852 mA g-1), have high capacity, stable and lasting cycling performance, which makes it promising to use polyhedral CoSn (OH) _6 as a precursor for a high performance integrated electrode.2., and to construct the soft of a graphene wrapped SnO_2-Co_3O_4 cube (G/SnO_2-Co_3O_4). The rational selection of the lithium ion battery, the rational selection of the composition of the composite electrode, the unique polyhedron nanostructure and the appropriate composite material construction method successfully produced the synergistic lithium storage effect, and realized the partial reversible conversion of the SnO_2 and Shi Moxi interface lithium storage, and the reversible capacity of the electric pole was still high after 100 cycles under 100 mA g-1. At the high current density of 1665 mAh g-1. at 1 A g-1, the electrode remains high capacity, stable cycle performance and long effective cycle life (1208 mAh g-1 after 1000 cycles). More importantly, the self supporting electrode prepared in this experiment can maintain its flexibility well after repeated 300 cycles of electrochemical cycle, which makes it expected to be high. One of the effective and stable flexible lithium ion battery electrode materials.3. first synthesized the mesoporous positive eight surface body Fe Co_2O_4. spinel mixed transition metal oxide used as the anode material for lithium ion batteries by the method of evaporation induced self assembly. The replacement of the partial metals in the mixed transition metal oxide of the spinel type of the mesoporous Fe Co_2O_4. can improve the lithium storage property. The structure can maintain the stability of the structure and improve the cycle performance. The mesoporous structure can shorten the charge transmission path, promote the flow and infiltration of the electrolyte, provide more surface area for the adsorption of lithium ion, and provide more space buffer volume. The product showed good electrochemical properties, including high capacity, rapid charge discharge and stable cycling performance (1 A g-1 cycle 200 cycles after 1101 mAh g-1), and the best ratio performance of Fe Co_2O_4 (518 m Ah g-1 under 10 A g-1), which was reasonably set up by hydrothermal method and successfully prepared the graphene quantum dots doped nanoparticle. XRD, GQDs/MoS_2, SEM, TEM and Raman techniques are used to characterize the structure. Doping GQDs expands the spacing of MoS_2, accelerates the electrochemical kinetics, and buffers the volume effect. It helps to enhance the advantages of MoS_2 in the structure and composition and improve the lithium storage energy. As a negative material for lithium ion batteries, GQDs/MoS_2 table High capacity, good cycling performance and multiplying performance. The GQDs doped into MoS_2 forms a large number of defects in the edge and base plane of the nanoscale, which is the key factor to improve the catalytic activity and electrical conductivity. At a low overpotential of 200 mV, it was 10 mA cm-2 and 74 mA cm-2 at low overpotential of 300mV and a low initial potential (140 mV).
【學(xué)位授予單位】：青島科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB383.1;TM912

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本文編號：1916569