本文關(guān)鍵詞：鋰離子電池負(fù)極材料多孔Si和Ge基材料的合成、表征及應(yīng)用　出處：《浙江大學(xué)》2015年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 鋰離子電池 負(fù)極材料 Si Ge 多孔結(jié)構(gòu)

【摘要】：鋰離子電池作為一種重要的便攜式電池其應(yīng)用日益廣泛,成為國際產(chǎn)業(yè)界和學(xué)術(shù)界關(guān)注的重點領(lǐng)域之一。四族元素材料Si和Ge被認(rèn)為是下一代鋰離子電池負(fù)極材料的理想候選材料,他們具有如下的優(yōu)勢：地殼含量較為豐富,理論比容量高,嵌鋰電位相對低。Ge相對于Si而言,具有更加快速的鋰離子遷移率和電子導(dǎo)電率,從而擁有更加優(yōu)良的電化學(xué)性能,但是其價格也更加的高昂。但是,Si和Ge都是屬于合金型反應(yīng)機理的材料,這二者材料都面臨著在合金化過程中具有較大體積膨脹的這一難題,限制了其實際應(yīng)用。因此,Ge和Si材料制備和合成以及作為鋰離子電池負(fù)極材料的性能成為一個國際上前沿問題。本文在概述了這兩種材料的研究現(xiàn)狀的基礎(chǔ)上,提出了制備Ge、Si多孔材料改善二者鋰離子電池的循環(huán)性能的思路；探究了兩種材料的多孔結(jié)構(gòu)的合成方法,發(fā)現(xiàn)了一種可大量制備多孔Si的新型合成方法；并研究了這兩種材料的多孔結(jié)構(gòu)對于鋰離子電池負(fù)極材料性能的提升。具體而言,論文取得了如下的創(chuàng)新研究成果：(1)通過球磨法制備了Mg2Si合金材料,首先研究了Mg2Si合金作為鋰離子電池負(fù)極材料的應(yīng)用,但是發(fā)現(xiàn)純的Mg2Si材料作為負(fù)極材料其循環(huán)性能非常差。為了改善其循環(huán)性能,采用了氣相法對其進(jìn)行表面碳層的包覆,從而發(fā)現(xiàn)Mg2Si@C材料的性能尤其是循環(huán)穩(wěn)定性得到了大幅提升,并對表面均勻包覆碳層提升電池循環(huán)穩(wěn)定性的機理進(jìn)行了探討。(2)采用Mg2Si為原料,對其熱穩(wěn)定性進(jìn)行了系統(tǒng)研究。研究發(fā)現(xiàn),Mg2Si在有氧的條件下特定的氣氛下高溫?zé)崽幚頃纸?可以得到多孔Si和MgO的前驅(qū)體,將其酸處理去除MgO之后就可以得到多孔Si材料,這是一種制備非常簡單、具備實用價值的多孔硅制備新途徑。論文對合成過程的粒徑因素、氧含量、熱處理溫度等影響因素進(jìn)行了詳細(xì)研究,為該技術(shù)的大規(guī)�；瘧�(yīng)用提供了基礎(chǔ)。進(jìn)一步地,研究不同形式碳包覆制備多孔的Si@C材料,獲得了更加好的鋰離子電池循環(huán)性能。(3)利用Mg2Si和Mg2Ge為原料,通過球磨和熱處理的方法制備得到了多孔SiGe復(fù)合材料。研究發(fā)現(xiàn)其反應(yīng)機理和Mg2Si分解類似；不同Si和Ge比例的材料對于負(fù)極材料的性能有著非常大的影響,Ge的比例越高,其電池的循環(huán)溫度性也越好,但是比容量相對而言比較低。(4)采用Si0為源,通過簡單的熱處理和酸處理制備得到多孔Si材料,從而提出了另外一條新的多孔Si的合成路徑。在詳細(xì)研究SiO在不同的熱處理條件的實驗之后,發(fā)現(xiàn)：在中低溫?zé)崽幚砗虷F處理條件下,可以得到納米si分散于SiOx體系的這一結(jié)構(gòu)；而在高溫?zé)崽幚砗虷F處理的條件下,可以得到多孔的Si-SiO2-SiOx這一結(jié)構(gòu)；用這種方法制備的多孔si作為負(fù)極材料,其電池具有一定的比容量和穩(wěn)定的循環(huán)性能。(5)利用Mg2Ge為源,通過改變反應(yīng)氣氛等條件,合成了新型多孔Ge納米結(jié)構(gòu)和多孔的Ge02納米結(jié)構(gòu)。在實驗中,通過Mg2Ge高溫分解和酸處理得到多孔的Ge,采用氧化性更強的氧氣氣氛或者延長反應(yīng)時間得到了多孔的Ge02納米結(jié)構(gòu)。經(jīng)過碳層包覆之后,該結(jié)構(gòu)作為負(fù)極材料的鋰離子電池表現(xiàn)了優(yōu)秀的循環(huán)性能和倍率性能。
[Abstract]:Lithium ion battery as a portable battery important is used more and more widely, has become one of the key areas of concern in the international industry and academia. The four element materials Si and Ge are considered as ideal candidate materials for lithium ion battery cathode material for the next generation, they have the following advantages: the content is more abundant, than theory high capacity lithium intercalation potential relative low.Ge compared with Si, with a more rapid lithium ion mobility and electronic conductivity, which has more excellent electrochemical performance, but its price is more expensive. However, Si and Ge belong to the reaction mechanism of alloy materials, these two materials are facing with this problem in alloying great volume expansion process, limit its practical application. Therefore, Ge and Si material preparation and synthesis as well as the properties of anode materials for lithium ion batteries become a country On the occasion of the frontier problem. In this paper, summarizes the research status quo of the two kinds of materials, put forward the preparation of Ge, Si porous material two to improve the cycle performance of the lithium ion battery research ideas; a synthesis method of porous structure of two kinds of materials, found a new synthetic method for preparation of large quantity porous Si; and study the promotion of porous structure of the two materials on the performance of anode materials for lithium ion batteries. Specifically, the paper made the following research: (1) were prepared by ball milling Mg2Si alloy, Mg2Si alloy have been studied first application as anode materials for lithium ion batteries, but found pure Mg2Si as anode material for the performance of the cycle is very poor. In order to improve the performance of the cycle, the vapor phase method of the coated carbon layer on the surface, so that the properties of Mg2Si@C materials especially cyclic stability Quality has been greatly improved, and the surface evenly coated carbon layer for improving the cell cycle stability mechanism is discussed. (2) using Mg2Si as raw material, the thermal stability was studied. The study found that the specific heat atmosphere at about the decomposition of Mg2Si under aerobic conditions, can obtain the precursor the porous Si and MgO, after the acid removal of MgO can get Si porous material, which is a kind of preparation is very simple and practical new way of preparing porous silicon. The synthesis process of particle size, oxygen content, heat treatment temperature and other factors were studied in detail. To provide a basis for the large-scale application of the technology. Further, to study the different forms of carbon coated porous Si@C material, the cycle performance of Li ion battery better. (3) using Mg2Si and Mg2Ge as raw materials by ball milling and hot The preparation method of prepared porous SiGe composites. The results indicated that the reaction mechanism and the decomposition of Mg2Si is similar to Si and Ge; different proportion of the material has a very large impact on the performance of anode materials, the ratio of Ge is higher, the temperature of the cell cycle is also better, but the capacity is relatively low. (4) using Si0 as the source, by a simple thermal treatment and acid treatment of the prepared porous Si materials, and put forward a new path in the synthesis of porous Si. Found in a detailed study of SiO after different heat treatment conditions in the experiment: in the middle and low temperature heat treatment and HF treatment under the conditions of this a structure can be obtained Si nanoparticles dispersed in SiOx system; and in high temperature heat treatment and HF treatment conditions, the porous structure can be obtained by the method of Si-SiO2-SiOx; preparation of porous Si as anode material, the battery has a certain Than the cycle performance of capacity and stability. (5) using Mg2Ge as the source, by changing the conditions of reaction atmosphere, Ge02 nano structure porous and porous Ge nanostructures were synthesized. In the experiment, through the decomposition of Mg2Ge at high temperature and acid treatment to obtain the porous Ge by oxidation of more oxygen or prolonging the reaction time the Ge02 nanostructured porous. After carbon coated, the structure as a cathode material of lithium ion battery shows excellent cycle performance and rate performance.

【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TM912;TB383.4

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