本文選題：三氧化鉬 + 二硫化鉬��； 參考：《陜西科技大學(xué)》2017年碩士論文

【摘要】：近年來,電動汽車和可移動電子產(chǎn)品的迅速發(fā)展極大地刺激了人們對于性能優(yōu)異的鋰離子電池的需求。人們正在積極地為鋰離子電池研究和尋找更高性能的電極材料。過渡金屬硫化物(TMS)由于其特殊的合金化或轉(zhuǎn)化反應(yīng)的儲鋰機(jī)制近年來吸引了越來越多的關(guān)注,相比于傳統(tǒng)的碳負(fù)極材料,TMS對實現(xiàn)高比容量更為有優(yōu)勢。其中,二硫化鉬(MoS_2),作為一種典型二維層狀結(jié)構(gòu)的TMS,由于其可以在一個相對較低的電位下儲鋰以及通過轉(zhuǎn)換機(jī)制實現(xiàn)更高的比容量而引起了更加廣泛的興趣。然而由于本身較差的導(dǎo)電性以及循環(huán)過程中結(jié)構(gòu)的不穩(wěn)定性等問題,MoS_2作為電極材料的循環(huán)和倍率性能并不能令人滿意。同樣作為一種過渡金屬化合物,三氧化鉬(MoO_3)與MoS_2具有很多的相似之處,例如高的理論比容量,較差的循環(huán)穩(wěn)定性等。針對這些問題,研究人員發(fā)現(xiàn),將MoS_2和MoO_3與導(dǎo)電性能優(yōu)良的材料結(jié)合構(gòu)建特殊結(jié)構(gòu)的復(fù)合材料可以很有效的改善電極材料的導(dǎo)電性和結(jié)構(gòu)穩(wěn)定性。因此,本論文主要圍繞MoS_2和MoO_3,通過復(fù)合不同的納米材料,構(gòu)建了多種具有特殊結(jié)構(gòu)的MoS_2和MoO_3基復(fù)合材料,以實現(xiàn)提高電化學(xué)性能的目的。通過多種測試手段,如XRD,XPS,Raman,SEM等對各個樣品進(jìn)行了表征,同時以各樣品作為活性材料組裝電池,測試和研究了各樣品的電化學(xué)儲鋰性能。本文主要的研究成果如下:(1)以鉬酸鈉為鉬源,氧化石墨烯為基體,采用一步水熱法制備了MoS_2/石墨烯復(fù)合材料(MoS_2-rGO)。所制備的復(fù)合材料中,MoS_2呈花球結(jié)構(gòu),直徑大約為400 nm,相對均勻地分散在石墨烯基體上。而片狀結(jié)構(gòu)的石墨烯則相互之間交織構(gòu)成了三維的導(dǎo)電網(wǎng)絡(luò)。由于這種特殊的復(fù)合結(jié)構(gòu)以及導(dǎo)電性優(yōu)異的石墨烯的引入,所制備的MoS_2-rGO復(fù)合材料表現(xiàn)出良好的電化學(xué)性能,當(dāng)電池充放電100次之后,電池的比容量能夠穩(wěn)定在900 mAh/g左右。(2)以MoO_3納米棒為無機(jī)前驅(qū)體,加入硫源,通過水熱法使MoO_3與硫離子發(fā)生離子交換,制備了MoO_3@MoS_2復(fù)合材料。通過添加不同量的硫脲(1 mM,3 mM,5 mM),制備了一系列的MoO_3@MoS_2復(fù)合材料。在最佳的硫脲添加量(3 mM)時,所制備的復(fù)合材料(MoO_3@MoS_2-II)是以一維的MoO_3納米棒為核,二維超薄的MoS_2納米片為殼,構(gòu)建的具有一維分層體系的核殼結(jié)構(gòu)復(fù)合材料。在MoO_3@MoS_2-II中,MoS_2納米片原位垂直生長在MoO_3納米棒,反應(yīng)產(chǎn)物一維結(jié)構(gòu)的保持取決于反應(yīng)體系溶劑的組成。電化學(xué)性能測試結(jié)果表明,這種由一維和二維材料構(gòu)建的核殼結(jié)構(gòu)復(fù)合材料具有優(yōu)異的電化學(xué)性能。在電流密度為100 mA/g,300 mA/g,500 mA/g,1000 mA/g對電池進(jìn)行充放電時,電池分別表現(xiàn)出929 mAh/g,642 mAh/g,510 mAh/g,384 mAh/g的平均放電比容量,更重要的是,在電流密度重新設(shè)置為100 mA/g時,電池的容量能夠維持在868 mAh/g,說明所制備的MoO_3@MoS_2具有良好的倍率性能。在電流密度為100 mA/g進(jìn)行充放電時,經(jīng)過100次充放電循環(huán)之后電極材料的比容量基本保持在781 mAh/g,說明MoO_3@MoS_2-II擁有良好的循環(huán)穩(wěn)定性。(3)通過磁力攪拌用氧化石墨烯將MoO_3進(jìn)行包裹,制備了MoO_3@GO復(fù)合材料。電化學(xué)性能測試表明,MoO_3@GO的儲鋰容量相對于MoO_3有了明顯地提高,首次放電容量達(dá)到1350 mAh/g,經(jīng)過60次循環(huán)之后,容量保持在720 mAh/g,并且從阻抗譜中可以看出,氧化石墨烯的加入使MoO_3@GO的導(dǎo)電性大大提高。隨后對MoO_3@GO進(jìn)行了硫化�，F(xiàn)有的測試結(jié)果表明,MoO_3@GO硫化產(chǎn)物(S-MoO_3@GO)可能是引入了硫的MoO_3@GO復(fù)合材料。MoO_3中引入硫之后,可能產(chǎn)生了氧空位,層間距增大,這些有利于電極反應(yīng)過程中電荷的快速運(yùn)動以及可以提高結(jié)構(gòu)的穩(wěn)定性,從充放電測試結(jié)果可以看出,S-MoO_3@GO在循環(huán)過程中除首次循環(huán)外,后續(xù)的容量極為穩(wěn)定,同時材料也表現(xiàn)出極好的倍率性能。
[Abstract]:In recent years, the rapid development of electric vehicles and mobile electronic products has greatly stimulated the needs of lithium ion batteries with excellent performance. People are actively studying and looking for higher performance electrode materials for lithium ion batteries. The transition metal sulfide (TMS) is close to the lithium storage mechanism of its special alloying or conversion reaction. More and more attention has been drawn over the years. Compared to the traditional carbon negative material, TMS has the advantage of achieving high specific capacity. Among them, molybdenum disulfide (MoS_2), as a typical two-dimensional layered structure of TMS, is caused by the ability to store lithium at a relatively low potential and to achieve higher specific capacity through a conversion mechanism. However, because of its poor conductivity and the instability of the structure during the cycle, the cycle and multiplying performance of MoS_2 as an electrode material is not satisfactory. As a transition metal compound, molybdenum trioxide (MoO_3) has a lot of similarities with MoS_2, such as high theoretical specific capacity, In order to solve these problems, the researchers found that the combination of MoS_2 and MoO_3 with excellent conductive materials to build a special composite material can effectively improve the conductivity and structural stability of the electrode materials. Therefore, this paper is mainly around MoS_2 and MoO_3, through the composite of different nanomaterials. A variety of MoS_2 and MoO_3 based composites with special structures were built to improve the electrochemical performance. Various samples were characterized by a variety of testing methods, such as XRD, XPS, Raman, SEM and so on. At the same time, each sample was used as the active material to assemble the battery. The electrochemical lithium storage properties of the samples were tested and studied. The results are as follows: (1) using sodium molybdate as the molybdenum source and graphene oxide as the matrix, MoS_2/ graphene composite (MoS_2-rGO) is prepared by one step hydrothermal method. In the composite materials, MoS_2 has a flower ball structure with a diameter of about 400 nm, which is relatively evenly dispersed on the graphene matrix. The flake structure of graphene is reciprocally crossed. With the introduction of this special composite structure and the introduction of graphene with excellent conductivity, the prepared MoS_2-rGO composite exhibits good electrochemical performance. When the battery is charged and discharged for 100 times, the specific capacity of the battery can be stabilized at about 900 mAh/ G. (2) MoO_3 nanorods as inorganic precursors, MoO_3@MoS_2 composites were prepared by ion exchange between MoO_3 and sulfur ions by hydrothermal method. A series of MoO_3@MoS_2 composites were prepared by adding different amounts of thiourea (1 mM, 3 mM, 5 mM). When the optimum addition of thiourea (3 mM), the prepared composite (MoO_3@MoS_2-II) was a one-dimensional MoO_3 nanorod. Nuclear, two dimensional ultra-thin MoS_2 nanoscale is a shell, and a nuclear shell structure composite with one dimension stratified system is constructed. In MoO_3@MoS_2-II, the MoS_2 nanoscale is in situ perpendicular to the MoO_3 nanorods. The one dimension structure of the reaction product depends on the composition of the reaction system solvent. The electrochemistry test results show that this kind is from one and two. The nuclear shell structure composite constructed by the material has excellent electrochemical performance. When the current density is 100 mA/g, 300 mA/g, 500 mA/g and 1000 mA/g, the battery shows the average discharge ratio of 929 mAh/g, 642 mAh/g, 510 mAh/g, 384 mAh/g, and more importantly, when the current density is reset to 100 mA/g, The capacity of the battery can be maintained at 868 mAh/g, indicating that the prepared MoO_3@MoS_2 has a good multiplier performance. When the current density is 100 mA/g, the specific capacity of the electrode material after 100 charging and discharging cycles is basically kept at 781 mAh/g, indicating that MoO_3@MoS_2-II has a good cycle stability. (3) the use of magnetic stirring is used. The MoO_3 was wrapped and MoO_3@GO composite was prepared by the graphite oxide. The electrochemical performance test showed that the lithium storage capacity of MoO_3@GO was significantly higher than that of MoO_3. The first discharge capacity reached 1350 mAh/g. After 60 cycles, the capacity remained at 720 mAh/g, and the addition of graphene oxide made M from the impedance spectrum. The conductivity of oO_3@GO is greatly improved. MoO_3@GO is then vulcanized. The existing test results show that the MoO_3@GO vulcanization product (S-MoO_3@GO) may be the introduction of sulfur in the MoO_3@GO composite.MoO_3 with sulfur, which may produce oxygen vacancies and increase the interlayer spacing, which are beneficial to the rapid motion of the charge in the electrode reaction. The stability of the structure can be improved. It can be seen from the test results of charge and discharge that the subsequent capacity of S-MoO_3@GO is very stable except for the first cycle in the cycle process, and the material also shows excellent multiplier performance.

【學(xué)位授予單位】：陜西科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB33

【參考文獻(xiàn)】

相關(guān)期刊論文 前4條

1 張晶晶;余愛水;;納米結(jié)構(gòu)過渡金屬氧化物作為鋰離子電池負(fù)極材料（英文）[J];Science Bulletin;2015年09期

2 顏劍;蘇玉長;蘇繼桃;盧普濤;;鋰離子電池負(fù)極材料的研究進(jìn)展[J];電池工業(yè);2006年04期

3 孫艷,馬珩,段潛,陳靜,戴寧;溶膠—凝膠法制備三氧化鉬電致變色薄膜的研究[J];光學(xué)儀器;2004年02期

4 任引哲,王建英,王玉湘;納米級MoO_3微粉的制備與性質(zhì)[J];化學(xué)通報;2002年01期

相關(guān)博士學(xué)位論文 前1條

1 王海騰;基于石墨烯的鋰離子電池負(fù)極材料的研究[D];北京交通大學(xué);2013年

相關(guān)碩士學(xué)位論文 前4條

1 紀(jì)珊珊;二硫化鉬納米復(fù)合材料的制備及其電化學(xué)性能研究[D];復(fù)旦大學(xué);2014年

2 馬鳳蘭;三氧化鉬（MoO_3）微晶的制備及其光催化性能研究[D];陜西科技大學(xué);2014年

3 宮方方;MoO_3的水熱法制備及其電化學(xué)性能研究[D];河南科技大學(xué);2013年

4 王軍;低維納米材料氧化鉬的制備及性能研究[D];華中科技大學(xué);2012年

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本文編號：1798735