碳包覆铁系氧化物复合微纳结构的合成与锂电性能研究

发布时间：2018-05-11 07:26

本文选题：锂离子电池 + 复合氧化物　；参考：《山东大学》2015年硕士论文

【摘要】：由于工业化规模的不断扩大,越来越多的国家出现环境污染、资源过度消耗等问题,能源危机已成为二十一世纪人们亟需解决的问题之一。随着传统不可再生资源储量的不断下降,以及地球生态环境持续恶化,仅仅依靠煤碳、石油、天然气等作为供能手段已不能满足人们日益增长的能源需求。寻找一种新型储能设备更显得尤为重要。锂离子电池作为一种新型环保储能载体,具有高效能、易携带、低污染等特点,因此成为人们重点研发的不二之选。目前,寻找新型环保、高寿命、大功率的电极材料来提升锂离子电池的性能成为了锂电池研究领域的重要目标。一直以来研究人员们都在积极寻找高比容量、高安全性、绿色环保、使用寿命长的新型负极材料,而过渡金属氧化物,由于其相当高的理论比容量,吸引了众多科研学者的目光。在此基础上,通过改进合成方法,构筑不同纳米结构的材料则可以更好地提高其电化学性能；此外,通过制备复合过渡金属氧化物,可以使得两种不同组分的特点相结合从而有效提升材料的各项性能。但过渡金属氧化物材料在充放电循环过程中存在巨大的体积形变且存在较高的首次不可逆容量,因此需要通过其他方法来对其进行修饰改进。本文从材料的制备和修饰两个方面展开研究,成功制备出了核壳结构的Fe3O4@C纳米管、蛋黄-蛋壳分离结构的Co2SnO4@C纳米立方块两种负极材料,通过透射电子显微镜(TEM)、扫描电子显微镜(SEM)、能谱仪(EDS)X-射线衍射(XRD)、拉曼光谱分析等分析手段进行研究,并对所制备材料进行了电化学测试。本论文的主要内容可归纳如下：1.采用水热法成功制备出了Fe2O3纳米管,再通过溶胶凝胶法在其表面包覆酚醛树脂(RF),经过氩气保护下煅烧,得到碳包覆的Fe3O4@C复合结构材料。经电化学测试证明了碳包覆后的电极材料具有更优秀的循环性能和倍率性能。2.通过常温下共沉淀反应得到CoSn(OH)6纳米立方块,随后在碱性条件下以正硅酸四乙酯(TEOS)为硅源通过Stober法对其包覆SiO2,再将酚醛树脂(RF)以溶胶凝胶法进行包覆,(?)气保护下煅烧,最后将中间层Si02用碱溶洗掉后得到具有空隙的蛋黄-蛋壳结构的Co2SnO4@C复合结构材料。经电化学测试表明了这种蛋黄-蛋壳结构能够有效地提升材料的循环性能和倍率性能。
[Abstract]:Due to the continuous expansion of industrialization, more and more countries appear environmental pollution, excessive consumption of resources and other issues, energy crisis has become one of the problems that people need to solve in the 21 century. With the unceasing decline of the traditional non-renewable resources and the continuous deterioration of the ecological environment of the earth, coal, oil, natural gas and other means of energy supply can no longer meet the increasing energy demand. It is more important to find a new type of energy storage equipment. As a new type of environmental energy storage carrier, lithium-ion battery has the characteristics of high efficiency, easy to carry, low pollution and so on. At present, it has become an important goal in the research field of lithium battery to find new type electrode materials with high life and high power to improve the performance of lithium ion battery. Researchers have been actively looking for new negative electrode materials with high specific capacity, high safety, green environment, long service life, and transition metal oxides, due to their high theoretical specific capacity. It has attracted the attention of many researchers. On the basis of this, the electrochemical properties of materials with different nanostructures can be improved better by improving the synthesis method, in addition, by preparing composite transition metal oxides, The properties of the materials can be effectively improved by combining the characteristics of the two different components. However, transition metal oxide materials have huge volume deformation and high first irreversible capacity during charge-discharge cycle, so they need to be modified by other methods. In this paper, the preparation and modification of Fe3O4@C nanotubes with core-shell structure and Co2SnO4@C nanoscale with yolk-shell separation structure were successfully prepared. Transmission electron microscopy (TEM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Raman spectroscopy (Raman) were used to study the materials. The main contents of this thesis can be summarized as follows: 1. Fe2O3 nanotubes were successfully prepared by hydrothermal method, and then coated with phenolic resin by sol-gel method. After calcined in argon atmosphere, carbon-coated Fe3O4@C composite structure materials were obtained. The electrochemical test shows that the carbon coated electrode material has better cycling performance and rate performance. 2. CoSn(OH)6 nanorods were prepared by coprecipitation reaction at room temperature. Then SiO2 was coated with tetraethyl orthosilicate (TEOS) as silicon source by Stober method, and phenolic resin was coated by sol-gel method. After calcined under gas protection, the intermediate layer Si02 was dissolved and washed with alkali to obtain the Co2SnO4@C composite structure with voids of yolk and eggshell structure. The electrochemical tests show that the yolk-eggshell structure can effectively improve the cycling performance and the rate performance of the material.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM912

【共引文献】