【摘要】：隨著高容量、高倍率、高安全性鋰離子電池發(fā)展的要求，石墨因其理論容量較低限制了其進(jìn)一步的研究和改善空間。而鍺基負(fù)極材料因嵌鋰容量高、嵌鋰電位適中和鋰離子擴(kuò)散系數(shù)大等優(yōu)點(diǎn)得到越來(lái)越多研究者們的關(guān)注。但成本高及嵌鋰過(guò)程中體積膨脹過(guò)大并導(dǎo)致循環(huán)性能差是阻礙其商業(yè)化應(yīng)用的關(guān)鍵問(wèn)題。本文以發(fā)展綜合性能優(yōu)良的Ge基體系負(fù)極材料為目標(biāo)，采用高能機(jī)械球磨法特別是首次引入介質(zhì)阻擋放電等離子體（DBDP）輔助高能球磨來(lái)制備Ge-C體系復(fù)合負(fù)極材料，主要研究了不同球磨方法和工藝對(duì)Ge-C復(fù)合材料的微觀結(jié)構(gòu)及電化學(xué)性能的影響。 本研究分別采用常規(guī)高能球磨法和介質(zhì)阻擋放電等離子體(DBDP)輔助高能球磨法，將純Ge粉和天然石墨粉直接混合球磨，，分別制備了不同形態(tài)的石墨包覆納米Ge顆粒結(jié)構(gòu)的Ge50C50材料。DBDP輔助球磨將石墨剝離成性能優(yōu)良的少層石墨烯，這種少層石墨烯對(duì)Ge基負(fù)極材料的結(jié)構(gòu)穩(wěn)定性和電化學(xué)性能的改善作用優(yōu)于常規(guī)球磨法中得到的團(tuán)絮狀石墨。在100mA/g的充/放電電流密度下，DBDP輔助球磨得到的復(fù)合材料Ge50C50經(jīng)過(guò)50次循環(huán)后容量仍保持為812.1mAh/g。將上述兩種球磨方法制備的Ge50C50材料分別添加還原氧化石墨烯(RGO)，并對(duì)比各自添加RGO前后的結(jié)構(gòu)和電化學(xué)性能，發(fā)現(xiàn)經(jīng)過(guò)50次循環(huán)后兩種Ge50C50RGO10復(fù)合材料的放電容量均提高約150mAh/g，但首次庫(kù)倫效率降低，被認(rèn)為是化學(xué)法制備少層石墨烯容易引入雜質(zhì)官能團(tuán)，導(dǎo)致電極材料首次循環(huán)的不可逆容量損失。 將膨脹石墨(EG)與預(yù)磨5h后的純Ge進(jìn)行DBDP輔助球磨10h，得到10層左右的少層石墨烯(FLG)包覆尺寸為150nm的純鍺顆粒的Ge@FLG復(fù)合結(jié)構(gòu)。Ge@FLG復(fù)合材料阻抗約90，循環(huán)50次后放電比容量為846.3mAh/g。隨球磨時(shí)間延長(zhǎng)，Ge@FLG材料的Ge顆粒尺寸無(wú)明顯變化，膨脹石墨被剝離成為少層石墨烯，儲(chǔ)鋰容量增加，循環(huán)更加穩(wěn)定，材料內(nèi)部阻抗降低，鋰離子擴(kuò)散動(dòng)力學(xué)性能提高。但DBDP輔助球磨能量輸出較大，球磨時(shí)間超過(guò)15h時(shí)Ge@FLG復(fù)合材料性能反而下降。
[Abstract]:With the development of high capacity, high rate and high safety lithium ion batteries, graphite has limited its further research and improvement due to its low theoretical capacity. However, germanium based anode materials have attracted more and more attention due to their high lithium intercalation capacity, moderate lithium intercalation potential and large lithium ion diffusion coefficient. However, high cost and excessive volume expansion in the process of lithium intercalation lead to poor cycle performance, which is a key problem that hinders its commercial application. The aim of this paper is to develop GE based negative electrode materials with good comprehensive properties. The high energy mechanical ball milling method, especially the introduction of dielectric barrier discharge plasma (DBDP) assisted high energy ball milling for the first time, is used to prepare Ge-C composite negative electrode materials. The effects of different ball milling methods and processes on the microstructure and electrochemical properties of Ge-C composites were studied. In this study, the pure GE powder and natural graphite powder were mixed directly by conventional high energy ball milling and dielectric barrier discharge plasma (DBDP) assisted high energy ball milling. Ge50C50 materials with different forms of graphite coated with nanocrystalline GE particles were prepared. DBDP-assisted ball milling was used to peel graphite into low-layer graphene with excellent properties. The structure stability and electrochemical performance of the Ge-base anode material were improved by using this kind of low-layer graphene, which was better than that obtained by conventional ball milling method. Under the charge / discharge current density of 100mA/g, the capacity of the composite Ge50C50 obtained by ball-milling is still 812.1mAh / g after 50 cycles. The structure and electrochemical properties of the Ge50C50 materials prepared by the two ball milling methods were compared by adding reduced graphene (RGO), and comparing the structure and electrochemical properties before and after the addition of RGO. It was found that after 50 cycles, the discharge capacity of the two Ge50C50RGO10 composites was increased by about 150mAh/ g, but the first Coulomb efficiency was decreased. It is considered that it is easy to introduce impurity functional groups into the preparation of less layer graphene by chemical method. The irreversible capacity loss of the electrode material is caused by the first cycle. The expanded graphite (EG) and the pure GE after 5 h pre-grinding were milled with DBDP for 10 h. The composite structure of 10 layers of (FLG) coated with pure germanium particles of 150nm was obtained. The impedance of the composite was about 90, and the specific discharge capacity of the composite was 846.3mAh. g after 50 cycles. With the prolongation of ball milling time, the GE particle size of Ge@ FLG material has no obvious change, and the expanded graphite is stripped into less layer graphene, the lithium storage capacity increases, the cycle becomes more stable, the internal impedance of the material decreases, and the diffusion kinetic properties of lithium ion are improved. However, the energy output of DBDP assisted ball milling is large, and the properties of Ge@FLG composites decrease when milling time exceeds 15 h.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM912

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 樂(lè)毅誠(chéng);石磊;吳飛;;鋰離子電池負(fù)極材料的研究進(jìn)展[J];船電技術(shù);2011年06期

2 楊小平;戴樂(lè)陽(yáng);曾美琴;歐陽(yáng)柳章;;介質(zhì)阻擋放電等離子體及其在材料制備中的應(yīng)用[J];材料導(dǎo)報(bào);2010年S1期

3 何向明;李建剛;王莉;任建國(guó);;鋰離子電池發(fā)展的前瞻——第14屆國(guó)際鋰電池會(huì)議評(píng)述[J];電池;2008年04期

4 呂成學(xué),褚嘉宜,翟玉春,田彥文;鋰離子電池氧化物負(fù)極材料的研究[J];東北大學(xué)學(xué)報(bào);2004年06期

5 萬(wàn)傳云;;鋰離子電池正負(fù)極材料市場(chǎng)發(fā)展趨勢(shì)[J];電池工業(yè);2005年06期

6 汪艷,馮熙康,杜友良,王伯良;鋰離子蓄電池材料的研究現(xiàn)狀[J];電源技術(shù);2001年03期

7 �？烧�,金志浩;高溫自潤(rùn)滑陶瓷復(fù)合材料研究進(jìn)展[J];硅酸鹽通報(bào);1998年05期

8 王國(guó)平,張伯蘭,瞿美臻,岳敏,許曉落,于作龍;改性球形天然石墨鋰離子電池負(fù)極材料的研究[J];合成化學(xué);2005年03期

9 呂成學(xué),褚嘉宜,翟玉春,田彥文;鋰離子電池銻基復(fù)合氧化物負(fù)極材料的研究[J];哈爾濱工業(yè)大學(xué)學(xué)報(bào);2004年10期

10 阿榮;王明東;姚宏林;苗琦;;鋰離子電池氧化物負(fù)極材料的研究進(jìn)展[J];化工新型材料;2008年10期

相關(guān)博士學(xué)位論文 前1條

1 胡仁宗;鋰離子電池Sn基薄膜負(fù)極的多相多尺度結(jié)構(gòu)與循環(huán)性能[D];華南理工大學(xué);2011年

本文編號(hào)：2153898