石墨烯在锂离子电池负极中的应用研究
发布时间：2018-11-06 12:39
【摘要】：摘要：传统碳材料(天然石墨)因其成本低、安全、循环稳定等特性,被广泛应用于现代商用锂离子电池负极材料。天然石墨作为锂离子电池的缺点是比容量低、充放电速率低。而另一类负极材料——氮、硅、锡基氧化物/化合物具有较高的比容量,充放电速率较天然石墨有所提高。但是,氮、硅、锡基氧化物／化合物作为锂离子电池负极材料具有一个致命的缺点,就是在充放电过程中,其体积变化过大,严重影响锂离子电池的安全性能,同时存在成本高的问题,从而限制这类负极材料的应用。基于以上,制备石墨烯及改性石墨烯(石墨烯分别与富勒烯、碳纳米管复合)成为弥补现有两类负极材料不足的潜在解决方案。 因此,本论文主要做了以下研究： (1)针对性地选取改性Hummers法制备氧化石墨烯,并用热还原法制得石墨烯,对制得的石墨烯进行AFM、SEM、XRD和Raman光谱分析； (2)研究了石墨烯作为锂离子电池负极材料的电化学性能。通过比容量、循环次数、库伦效率等方面进行分析,结果表明,作为锂离子电池负极,石墨烯的比容量优于天然石墨。天然石墨的理论容量为372mAh/g,石墨烯的理论容量为744mAh/g,而实验中获得石墨烯的首次嵌锂容量平均值为861.5mAh/g.石墨烯在2C倍率下,100次循环后容量为280mAh/g; (3)研究了石墨烯与富勒烯复合,作为锂离子电池负极材料的电化学性能。通过比容量、循环次数、库伦效率等方面进行分析,结果表明,作为锂离子电池负极,石墨烯与富勒烯复合优于纯石墨烯。首次嵌锂容量平均值由861.5mAh/g提升到1026.6mAh/g;2C倍率下,100次循环后,比容量由280mAh/g提升到301mAh/g;平均库伦效率由97.7%提升到97.9%； (4)研究了石墨烯与碳纳米管复合,作为锂离子电池负极材料的电化学性能。通过比容量、循环次数、库伦效率等方面进行分析,结果表明,作为锂离子电池负极,石墨烯与碳纳米管复合优于石墨烯与富勒烯复合。首次嵌锂容量平均值由1026.6mAh/g提升到1270.6mAh/g;2C倍率下,100次循环后,比容量由301mAh/g提升到365mAh/g;平均库伦效率由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%.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912
本文编号：2314296
[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%.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912
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相关期刊论文 前2条
1 杨全红;唐致远;;新型储能材料——石墨烯的储能特性及其前景展望[J];电源技术;2009年04期
2 杨全红;吕伟;杨永岗;王茂章;;自由态二维碳原子晶体—单层石墨烯[J];新型炭材料;2008年02期
，本文编号：2314296
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