含锡锂离子电池复合负极材料的制备及其电化学性能研究

发布时间：2018-04-01 20:24

本文选题：锂离子电池　切入点：复合氧化物　出处：《山东大学》2016年硕士论文

【摘要】：随着传统能源的过度消耗,环境污染日益严重,人们对环保高效的新能源需求越来越强烈,其中锂离子电池是其中的佼佼者,已经吸引了广泛的关注。随着移动电子设备,电动汽车以及大型储能装置的广泛应用,需要继续研究以满足锂离子电池长寿命、高容量、高性能的要求。目前大量应用的石墨负极材料,理论可逆容量仅为372 mAh g-1,已不能满足使用者对高性能锂离子电池的需要。二氧化锡用作锂离子电池负极材料具有较高的体积与质量比容量,因而具有非常大的应用前景。但二氧化锡作为负极材料,在锂离子的嵌入和脱出过程中产生巨大体积膨胀,造成电极材料的粉化与团聚,从而使锂离子电池寿命与容量快速衰减。二氧化锡通过与其他物质复合可以充分发挥其自身高体积比容量与高质量比容量的优势,从而获得具有较高性能的锂离子电池负极材料,而且通过二氧化锡与其他材料复合能够发挥异种材料的相互隔离与分散作用。本文主要研究内容如下：(1)通过简单的沉淀法制备了具有不同Ti/Sn摩尔比的Ti-Sn-O复合氧化物,并采用吡啶,吡咯,葡萄糖作为碳源进行包碳处理。对复合氧化物与单一物质进行了电化学性能的测试与分析。相对于单一的物质TiO_2与SnO_2,当复合材料Ti/Sn摩尔比为1.7／0.3时,用吡啶作为碳源进行碳包覆时具有最优异的电化学性能。相对于单一TiO_2与SnO_2,Ti-Sn-O复合材料电化学性能的提高归因于复合物中TiO_2高的结构稳定性,Ti-Sn-O复合氧化物具有相对更小的晶粒尺寸以及在充放电过程中TiO_2与SnO_2两种元素的相互隔离作用,抑制材料晶体颗粒长大。(2)通过草酸锡与二茂铁一步反应合成了Fe3O_4、FeSn、Fe3C和碳纳米管复合材料(Sn-Fe-O-C)。电化学性能测试表明,当草酸锡与二茂铁比例为1／9,烧结温度为550 ℃时达到了较好的电化学性能,这可能是因为较低的烧结温度使无定型碳较多,增加了活性储锂位置。另外复合材料中的碳纳米管能够提高材料的导电性缓解抑制材料的体积膨胀与团聚。Fe-Sn合金中的惰性物质Fe也可有效缓解抑制电化学反应中生成Li-Sn合金产生的体积膨胀及提高材料的导电性。而Fe3O_4外面的Fe_3C层可以有效缓解Fe3O_4的体积膨胀并提高材料的导电性。
[Abstract]:With the excessive consumption of traditional energy and the increasingly serious environmental pollution, people on environmental protection and efficient new energy demand is more and more intense, the lithium ion battery is one of the best, has attracted wide attention. With the development of mobile electronic devices, widely used in electric cars and large energy storage devices, the need to continue to study in order to meet the needs of lithium ion battery long life, high capacity, high performance requirements. The widely used graphite anode material, the theory of reversible capacity is only 372 mAh g-1, has been unable to meet the users of high performance lithium ion batteries. Two tin oxide as anode material for lithium ion batteries with higher volume and quality than the capacity, so it has wide application prospect big. But the two tin oxide as anode materials, huge volume expansion during insertion and extraction process of lithium ion in the resulting powder electrode material together with, so that The rapid attenuation of lithium ion battery life and capacity. By two tin oxide compound with other substances can give full play to its own high volume and high quality than the capacity advantages, so as to obtain anode materials for lithium ion batteries with high performance, and by two he and tin oxide composite materials can play mutual isolation and dispersion of dissimilar materials. The main contents are as follows: (1) through a simple precipitation method to prepare Ti-Sn-O composite oxides with different Ti/Sn molar ratio, and the use of pyridine, pyrrole, glucose as carbon source. The carbon coated composite oxide and single material were tested and analyzed. The electrochemical properties of TiO_2 and SnO_2 compared with the single material when the composite, Ti/Sn molar ratio is 1.7 / 0.3, using pyridine as carbon source has excellent electrochemical performance of carbon coated when compared to the single. A TiO_2 and SnO_2. The electrochemical performance of Ti-Sn-O composites increase due to the high structure stability of the TiO_2 complex, isolated Ti-Sn-O composite oxides with two elements and a relatively smaller grain size of TiO_2 in the process of charge and discharge and SnO_2, inhibit the crystal growth of materials. (2) Fe3O_4, was synthesized by oxalic acid the two step reaction of tin and iron Mao FeSn, Fe3C and carbon nanotube composite material (Sn-Fe-O-C). The electrochemical performance test showed that when oxalate tin and two ferrocene ratio of 1 / 9, the sintering temperature is 550 DEG C to electrochemical performance better, this may be because the low sintering temperature of amorphous carbon. More, increase the activity of lithium storage location. In addition, the composite of carbon nanotubes can improve the conductivity of the material response inhibiting material volume expansion and agglomeration of.Fe-Sn alloy inert material also can relieve Fe The volume expansion and the electrical conductivity of Li-Sn alloy can be inhibited by electrochemical reaction. The Fe_3C layer outside Fe3O_4 can effectively relieve the volume expansion of Fe3O_4 and improve the electrical conductivity of materials.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM912

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