碳包覆混晶二氧化钛纳米管锂离子电池负极材料的制备及性能研究

发布时间：2018-01-22 06:17

  本文关键词： 锂离子电池 二氧化钛 混晶 纳米管 多巴胺　出处：《北京化工大学》2016年硕士论文　论文类型：学位论文

【摘要】：近年来,随着环境污染问题逐渐得到了大众关注,锂离子电池作为一种清洁的汽车动力能源越来越受到重视,由此对锂离子电池的能量密度和安全性能提出了更高的要求。此外,随着手机等电子产品屏幕越来越大,耗电越来越快,锂离子电池的容量和倍率性能也成了衡量锂离子电池品质的关键。二氧化钛(TiO2)具有廉价、环保的特点,其纳米材料作为锂离子电池负极具有理论容量高、安全性能好、能量密度高、充放电平台高、可快速充放电等优点,是十分有前景的锂离子电池负极材料。其中的一维纳米TiO2由于具有两方向的锂离子传输通道,可以通过很大的电流快速充放电,能够满足人们对电动交通工具和数码产品快速充放电的需要。此外一维纳米TiO2采用水热法制备,操作简便,具有商用推广的条件。本文采用水热法制备一维纳米TiO2,探究水热温度、烧结温度对一维纳米TiO2的形貌和电化学性能的影响,得到两种TiO2-B晶型和锐钛矿晶型同时存在的TiO2纳米管(TiO2-400和TiO2-500),这两种混晶TiO2纳米管均具有较高的容量、良好的循环性能和优异的倍率性能。为进一步提高混晶TiO2纳米管的性能,尝试采用石墨烯和多巴胺包覆对混晶TiO2纳米管进行碳包覆,其中多巴胺包覆6h后700℃碳化所得的材料具有TiO2-B晶型和锐钛矿晶型混合的管型结构,以及合适厚度(-2nm)的碳包覆层,从而同时具有高容量、高倍率性能及高循环稳定性的优点。该材料以200mA·g-1电流密度500次循环后容量保持在177.5mAh·g-1,大电流密度2000mA·g-1下容量为141.2mAh·9-1,600次大电流密度循环后(2000mA·g-1),容量仍然维持在140.5mAh·g-1。
[Abstract]:In recent years, with the environmental pollution problem gradually getting the attention of the public, lithium ion battery as a kind of clean automobile power energy has been paid more and more attention. As a result, the energy density and safety performance of Li-ion batteries are required higher and higher. In addition, as the screen of electronic products such as mobile phones becomes larger and larger, the power consumption becomes faster and faster. The capacity and performance of lithium-ion batteries have also become the key to evaluate the quality of lithium-ion batteries. Titanium dioxide (TIO _ 2) has the characteristics of low cost and environmental protection. As a negative electrode of lithium ion battery, nano-material has the advantages of high theoretical capacity, good safety performance, high energy density, high charging and discharging platform, rapid charging and discharging, and so on. It is a promising cathode material for lithium-ion batteries, in which one-dimensional nanocrystalline TiO2 can charge and discharge rapidly through a large current due to its two-direction lithium ion transmission channel. It can meet the need of rapid charge and discharge of electric vehicles and digital products. In addition, one-dimensional nanocrystalline TiO2 is prepared by hydrothermal method, which is easy to operate. In this paper, one-dimensional nano-TiO _ 2 was prepared by hydrothermal method. The effects of hydrothermal temperature and sintering temperature on the morphology and electrochemical properties of one-dimensional nano-TiO _ 2 were investigated. Two kinds of TiO2 nanotubes, TiO2-400 and TiO2-500, with both TiO2-B and anatase crystal forms were obtained. These two kinds of mixed-crystal TiO2 nanotubes have high capacity, good cycling performance and excellent rate performance, in order to further improve the properties of mixed-crystal TiO2 nanotubes. Carbon coating of mixed crystal TiO2 nanotubes with graphene and dopamine was attempted. The materials obtained by carbonization at 700 鈩，

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