锂离子电池用二氧化钛负极材料的制备研究

发布时间：2018-05-27 06:24

本文选题：锂离子电池 + 负极材料　；参考：《青海大学》2017年硕士论文

【摘要】：锂离子电池由于具有能量密度大、功率密度高、自放电率小、循环寿命长、无记忆效应、体积及质量比能量高、使用温度范围广、环境友好等诸多优点已逐渐在移动通信,手机,笔记本电脑等电子设备中得到了广泛的应用。二氧化钛由于具有较高的工作电压(1.7V vs.Li/Li~+)及良好的结构稳定性,引起了人们的关注。本文以二氧化钛为研究对象制备出了系列材料,采用XRD,SEM,BET,XPS等测试方法对该系列材料进行了表面形貌和结构的表征,并且将其作为负极材料组装成电池,测试其电化学性能。主要的研究内容如下:首先,以三氯化钛为钛源,乙二醇为溶剂,通过溶剂热法合成TiO2-B。测试结果表明:TiO_2-B较锐钛矿具有更加优异的循环稳定性和良好的倍率性能。在5C电流密度下,放电比容量基本维持在147.5mAhg~(-1)左右不衰减。其次,以钛酸丁酯为钛源,溶剂(乙酸乙酯、乙酸、异丙醇)为生长助剂,通过溶剂热法合成不同形貌的二氧化钛。测试结果表明:样品的循环稳定性较差,在5C倍率下循环100次后,放电比容量分别为22.1,25.7,40mAhg-1。最后,采用简单的一步溶剂热法制备了Cu~(2+)掺杂的TiO_2纳米颗粒。电化学测试结果表明:掺杂可以明显提高材料的电化学性能。其中,掺杂的量有一个最佳值(样品S-6wt%),在5C电流密度下,首次放电比容量为83.4mAhg~(-1),经过100次充放电循环后放电比容量仍为76.5mAhg~(-1),具有良好的循环稳定性。
[Abstract]:Lithium-ion batteries have many advantages such as high energy density, high power density, low self-discharge rate, long cycle life, no memory effect, high volume and mass specific energy, wide range of temperature, friendly environment and so on. Mobile phones, laptops and other electronic devices have been widely used. Titanium dioxide has attracted much attention due to its high operating voltage of 1.7V vs.Li _ (r. Li~) and good structural stability. In this paper, a series of titanium dioxide materials were prepared. The surface morphology and structure of the series materials were characterized by means of XRDX SEMBET-XPS, and they were assembled as negative electrode materials to form batteries, and their electrochemical properties were tested. The main contents are as follows: firstly, TiO2-B was synthesized by solvothermal method with titanium trichloride as the source and ethylene glycol as the solvent. The results show that the ratio of TiO2-B to TiO2-B is better than that of anatase. At the current density of 5C, the specific discharge capacity is maintained at about 147.5 mAhg-1). Secondly, using butyl titanate as titanium source and solvent (ethyl acetate, acetic acid, isopropanol) as growth aids, different morphologies of titanium dioxide were synthesized by solvothermal method. The results show that the cycle stability of the sample is poor. After 100 cycles at 5C ratio, the specific discharge capacity is 22.1g ~ 25.7m 路g ~ (-1). Finally, TiO_2 nanoparticles doped with Cu~(2 were prepared by a simple one step solvothermal method. The results of electrochemical measurement show that doping can obviously improve the electrochemical performance of the materials. Among them, the doping amount has an optimum value (sample S-6 wt1). At 5C current density, the first discharge specific capacity is 83.4 mAhgt-1, and the discharge specific capacity is still 76.5 mAhgt-1 after 100 charge-discharge cycles, which shows good cyclic stability.
【学位授予单位】：青海大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ134.11;TM912

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