【摘要】：摘要：傳統(tǒng)碳材料(天然石墨)因其成本低、安全、循環(huán)穩(wěn)定等特性,被廣泛應(yīng)用于現(xiàn)代商用鋰離子電池負極材料。天然石墨作為鋰離子電池的缺點是比容量低、充放電速率低。而另一類負極材料——氮、硅、錫基氧化物/化合物具有較高的比容量,充放電速率較天然石墨有所提高。但是,氮、硅、錫基氧化物／化合物作為鋰離子電池負極材料具有一個致命的缺點,就是在充放電過程中,其體積變化過大,嚴(yán)重影響鋰離子電池的安全性能,同時存在成本高的問題,從而限制這類負極材料的應(yīng)用�；谝陨�,制備石墨烯及改性石墨烯(石墨烯分別與富勒烯、碳納米管復(fù)合)成為彌補現(xiàn)有兩類負極材料不足的潛在解決方案。 因此,本論文主要做了以下研究： (1)針對性地選取改性Hummers法制備氧化石墨烯,并用熱還原法制得石墨烯,對制得的石墨烯進行AFM、SEM、XRD和Raman光譜分析； (2)研究了石墨烯作為鋰離子電池負極材料的電化學(xué)性能。通過比容量、循環(huán)次數(shù)、庫倫效率等方面進行分析,結(jié)果表明,作為鋰離子電池負極,石墨烯的比容量優(yōu)于天然石墨。天然石墨的理論容量為372mAh/g,石墨烯的理論容量為744mAh/g,而實驗中獲得石墨烯的首次嵌鋰容量平均值為861.5mAh/g.石墨烯在2C倍率下,100次循環(huán)后容量為280mAh/g; (3)研究了石墨烯與富勒烯復(fù)合,作為鋰離子電池負極材料的電化學(xué)性能。通過比容量、循環(huán)次數(shù)、庫倫效率等方面進行分析,結(jié)果表明,作為鋰離子電池負極,石墨烯與富勒烯復(fù)合優(yōu)于純石墨烯。首次嵌鋰容量平均值由861.5mAh/g提升到1026.6mAh/g;2C倍率下,100次循環(huán)后,比容量由280mAh/g提升到301mAh/g;平均庫倫效率由97.7%提升到97.9%； (4)研究了石墨烯與碳納米管復(fù)合,作為鋰離子電池負極材料的電化學(xué)性能。通過比容量、循環(huán)次數(shù)、庫倫效率等方面進行分析,結(jié)果表明,作為鋰離子電池負極,石墨烯與碳納米管復(fù)合優(yōu)于石墨烯與富勒烯復(fù)合。首次嵌鋰容量平均值由1026.6mAh/g提升到1270.6mAh/g;2C倍率下,100次循環(huán)后,比容量由301mAh/g提升到365mAh/g;平均庫倫效率由97.9%提升到98.0%。
[Abstract]:Abstract: traditional carbon materials (natural graphite) are widely used in commercial anode materials for lithium ion batteries due to their low cost, safety, cycle stability and other characteristics. The disadvantages of natural graphite as lithium ion battery are low specific capacity and low charge / discharge rate. The other kind of anode materials nitrogen, silicon, tin based oxides / compounds have higher specific capacity and higher charge-discharge rate than natural graphite. However, nitrogen, silicon and tin oxides / compounds as anode materials for lithium ion batteries have a fatal disadvantage, that is, their volume changes too much during charge and discharge, which seriously affects the safety performance of lithium ion batteries. At the same time, there is the problem of high cost, which limits the application of this kind of negative electrode materials. Based on the above, the preparation of graphene and modified graphene (graphene, fullerene, carbon nanotube (CNT) is a potential solution to make up for the shortage of two kinds of negative electrode materials. Therefore, this paper mainly did the following research: (1) the graphene oxide was prepared by modified Hummers method, and the graphene was prepared by thermal reduction method. The graphene was analyzed by AFM,SEM,XRD and Raman spectra. (2) the electrochemical performance of graphene as anode material for lithium ion battery was studied. The specific capacity, cycle times and Coulomb efficiency are analyzed. The results show that graphene is superior to natural graphite as the anode of lithium ion battery. The theoretical capacity of natural graphite is 372mAh/ g, the theoretical capacity of graphene is 744mAh/ g, and the average of the first lithium intercalation capacity of graphene is 861.5mAh/ g. The capacity of graphene was 280 mg / g after 100 cycles at 2C ratio. (3) the electrochemical properties of graphene and fullerene as anode materials for lithium ion batteries were studied. The results show that graphene and fullerene are superior to pure graphene as anode of lithium ion battery by specific capacity, cycle times and Coulomb efficiency. For the first time, the average lithium intercalation capacity was raised from 861.5mAh/g to 1026.6mAh/ g ~ 2C, after 100 cycles, the specific capacity increased from 280mAh/g to 301 mAh-g, the average Coulomb efficiency increased from 97.7% to 97.9%. (4) the electrochemical properties of graphene and carbon nanotubes as anode materials for lithium ion batteries were studied. The specific capacity, cycle times and Coulomb efficiency were analyzed. The results showed that graphene and carbon nanotube were better than graphene and fullerene as anode of lithium-ion battery. For the first time, the average lithium intercalation capacity was raised from 1026.6mAh/g to 1270.6 mAh/ g ~ 2C. After 100 cycles, the specific capacity increased from 301mAh/g to 365 mAh-g, and the average Coulomb efficiency increased from 97.9% to 98.0%.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM912

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本文編號：2314296