碳素纳米材料的制备及其在锂—硫电池和锂离子电池中的应用

发布时间：2018-01-08 19:27

本文关键词：碳素纳米材料的制备及其在锂—硫电池和锂离子电池中的应用　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：石墨烯和氧化石墨烯作为重要的纳米碳材料具有特殊的结构和优异的性能,在能源技术、物理化学、生物医药等多个领域得到广泛应用。多孔结构碳材料用于制备锂离子电池负极材料和锂-硫复合正极材料对提升锂离子电池和锂-硫电池的电化学性能具有重要意义。本学位论文首先综述了氧化石墨烯、还原石墨烯的结构、性能和制备方法以及各种碳材料应用于锂离子电池负极材料和锂-硫电池复合正极材料的研究现状,以实现高效、可靠制备高质量氧化石墨烯、还原石墨烯和提升碳材料应用于锂离子电池和锂-硫电池电化学性能为目标。一方面,采用改进的Hummers法制备氧化石墨,通过设计不同的氧化参数研究氧化石墨中官能团含量和氧化石墨层间距的变化,优化氧化过程;进一步研究了超声和热剥离制备氧化石墨烯和还原石墨烯过程中剥离参数对产物形貌和结构的影响,确定了高效、可靠制备少层氧化石墨烯和还原石墨烯的制备参数。另一方面,通过制备多孔结构碳纳米微球,考察其应用于锂离子电池负极材料和锂-硫电池复合正极材料中的电化学性能;在上述研究的基础上,结合氧化石墨烯、还原石墨烯和多孔碳在锂-硫电池复合正极材料中的优点制备分层结构介孔碳包覆石墨烯复合材料,考察其应用于锂-硫电池复合正极材料的电化学性能。具体研究内容包括以下几个部分:(1).氧化过程中通过IR和XRD检测研究高锰酸钾与石墨的配比、氧化时间和氧化温度对氧化石墨中官能团含量和氧化石墨层间距的影响,得出高锰酸钾与石墨的配比为5:1,在45℃下氧化8 h制备的氧化石墨层间距达到0.97 nm,氧化石墨中含有大量的含氧官能团,该条件下石墨被充分氧化。通过对不同超声功率、超声时间和热剥离温度下氧化石墨烯和还原石墨烯结构形貌的研究,确定了采用超声功率为150-200 W,超声时间3-5 h可以高效制备少层氧化石墨烯;热剥离温度高于750℃条件下,可以高效剥离制备少层还原石墨烯。通过对氧化过程和剥离过程参数的研究使得采用Hummers法制备少层氧化石墨烯和还原石墨烯更加高效、可靠。以优化剥离温度制备得到的少层还原石墨烯作为前驱体,在高温下采用Ar/H2(85:15,v/v)混合气体在800℃下处理4 h进一步还原得到高还原程度还原石墨烯,该还原石墨烯中碳原子含量达到了 97.2%,氧原子含量只有2.8%,具有较高的还原程度。(2).室温下制备球形结构酚醛树脂微球,通过惰性气氛下碳化制备碳纳米微球,进一步采用CO2气氛活化制备高比表面积多孔碳纳米微球,研究碳纳米微球和多孔碳纳米微球作为锂离子电池负极材料的电化学性能,在210 mAg-1电流密度下,碳微纳米微球和多孔碳纳米微球作为负极材料的首次放电比容量达到482.4 mAh g-1和2575.9 mAh g-1,50次循环放电容量保持429.4 mAh-1和1000.0 mAh g-1,相同电流密度下其首次放电容量提升了5.4倍,50次循环放电容量提升了 2.3倍,微孔结构对提升锂离子电池碳基负极材料的比容量具有显著作用。(3).以(2)制备的多孔结构碳纳米微球作为硫的载体高效分散和附载硫制备锂-硫电池复合正极材料,当该复合正极材料中硫含量为53.5%时材料具有较好的电化学性能,在0.1C电流密度下首次放电比容量达到1274.0 mAh g-1,50次循环容量保持776.4 mAh g-1;1C电流密度下首次放电比容量达到830.3 mAh g-1,50次循环容量保持初始容量的78%,充放电效率高达100%。(4).结合氧化石墨烯、石墨烯的和多孔碳的特点和优点采用(1)条件下制备的少层氧化石墨烯作为载体,通过模板法和溶胶凝胶包覆法制备分层结构介孔碳包覆石墨烯复合材料附载硫制备锂-硫电池复合正极材料,该复合正极材料在低电流密度下具有较高的放电比容量,0.1C电流密度下首次放电容量为1158.1 mAh g-1;0.5C电流密度下首次放电比容量达到1131.3 mAh g-1,在大电流密度2C下的首次放电比容量达到600.3 mAh g-1。该复合电极材料在0.1C,0.5C,1C和2C倍率下10次循环的平均容量分别为1009.9 mAh g-1,737.3 mAh g-1,664.4 mAh g-1,492.8 mAh g-1。
[Abstract]:Graphene and graphene oxide as important carbon nano materials have special structure and excellent performance, in energy technology, physical chemistry, has been widely used in many fields such as biomedicine. Porous carbon materials used for the preparation of anode materials for lithium ion batteries and lithium - sulfur composite cathode materials for lithium ion batteries and lithium ascension - plays an important role in the electrochemical performance of sulfur batteries. This thesis reviews the structure of reduced graphene oxide, graphene, performance and preparation method and application of carbon materials in the research status of lithium ion battery cathode material and lithium - sulfur electric Chi Fuhe cathode materials, to achieve efficient and reliable preparation of high quality oxidation graphene, graphene and carbon reduction promotion materials used in the electrochemical performance of lithium ion battery and lithium sulfur battery as the goal. On the one hand, the preparation of graphite oxide by modified Hummers method, through Changes in content of functional groups and graphite oxide layer spacing of graphite oxide oxidation parameters of different design, optimization of oxidation process; further research on ultrasonic and thermal exfoliation of graphene oxide was prepared and the effect of stripping parameters reduced graphene process on the morphology and structure, determine the effective parameters for preparing reliable preparation layer the reduction of graphene oxide and graphene. On the other hand, the porous structure of carbon nanoparticles through the system, its application in the study of electrochemical performance of composite cathode material for lithium ion battery cathode materials and lithium sulfur batteries; based on the above research, combining the advantages of graphene oxide reduction in composite cathode materials lithium sulfur battery in graphene and preparation of porous carbon layer structure of mesoporous carbon coated graphene composite material, its application in the study of electrochemical performance of cathode material of lithium sulfur battery. The concrete research content Includes the following parts: (1) the ratio of IR and XRD. Through the detection of Potassium Permanganate and graphite in the oxidation process, oxidation time and temperature on the effect of functional group content and graphite oxide layer spacing of graphite oxide and graphite, that Potassium Permanganate ratio is 5:1, under the temperature of 45 DEG C oxidation graphite oxide layer spacing of 8 h the preparation of up to 0.97 nm, graphite oxide containing abundant oxygen-containing functional groups, the condition of graphite is fully oxidized. Based on different ultrasonic power, graphene oxide and graphene structure morphology of reduction under ultrasonic treatment time and temperature, were determined by ultrasonic power of 150-200 W, 3-5 h, ultrasonic time preparation of few layer graphene oxide; thermal stripping temperature higher than 750 DEG C under the condition of efficient preparation of stripping layer reduction of graphene. Through the study of the oxidation process and the parameters of the stripping process using Hummers Preparation of few layer graphene oxide and reduced graphene more efficient and reliable. With the reduction of graphene layer stripping temperature optimization prepared as precursor by Ar/H2 at high temperatures (85:15, v/v) H 4 mixed gas treatment and further reduction to obtain high degree of reduction of reduced graphene under 800 degrees, the reduction the content of carbon atoms in graphene reached 97.2%, oxygen content of only 2.8%, the reduction degree is higher. (2). The preparation of spherical structure of phenolic resin microspheres were prepared by carbonization at room temperature under inert atmosphere of carbon nanospheres, with further CO2 atmosphere of preparation of high specific surface area activated carbon nano porous microspheres, research carbon nano porous carbon microspheres and nanospheres electrochemical performance as anode materials for lithium ion batteries, under the current density of 210 mAg-1, carbon nano microspheres and porous carbon microspheres as anode materials of the first discharge capacity Up to 482.4 mAh g-1 and 2575.9 mAh g-1,50 cycles the discharge capacity remained 429.4 mAh-1 and 1000 mAh g-1, the same current density of the first discharge capacity increased by 5.4 times, 50 cycles the discharge capacity of up to 2.3 times, to improve the pore structure of carbon based anode materials for lithium ion battery capacity has a significant role. (3) (2). The porous structure of carbon nanospheres prepared as sulfur carrier dispersion and preparation of high sulfur loaded composite cathode material of lithium sulfur battery, when the sulfur content of the composite cathode materials of 53.5% materials have better electrochemical performance, the current density of 0.1C in the first discharge capacity reached 1274 mAh g-1,50 the cycling capacity retention 776.4 mAh g-1; the current density of 1C the first discharge capacity reached 830.3 mAh g-1,50 cycles the capacity to maintain the initial capacity of 78%, the charge discharge efficiency is as high as 100%. (4). Combined with the graphene oxide, graphite The characteristics and advantages of graphene and porous carbon (1) with few layer graphene oxide as the carrier prepared by template method, and sol gel coating prepared by layered structure of mesoporous carbon coated graphene composite material with sulfur preparation of composite cathode material of lithium sulfur battery, the composite cathode material has high the low current density, the discharge capacity of 0.1C current density under the first discharge capacity of 1158.1 mAh g-1; the current density of 0.5C the first discharge capacity reached 1131.3 mAh g-1, the first discharge at high current density of 2C is lower than the capacity of 600.3 mAh g-1. of the 0.5C composite electrode materials in 0.1C, 1C, and 2C rate average the capacity of 10 cycles was 1009.9 mAh g-1737.3 mAh g-1664.4 mAh g-1492.8 mAh g-1.

【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;TM912

【相似文献】