锂离子电池Ge基负极材料的制备及其储锂性能研究

发布时间：2018-05-12 02:20

本文选题：锂离子电池 + Ge负极　；参考：《郑州大学》2017年硕士论文

【摘要】：作为储能设备的锂离子电池(LIBs)具有能量密度高、功率大、寿命长和环境友好等特点。但市售LIBs石墨负极的理论容量仅有372 mAh g~(-1),这难以满足能量储存系统的建立、大型电动汽车等发展的要求。负极材料是LIBs的重要组成部分,因而,高容量负极材料的开发成为提高LIBs性能的决定因素。作为锂离子电池负极材料,Ge具有比容量高,操作电压低、电子传输速率快等优势,有望替代石墨负极。但在循环过程中,Ge体积膨胀严重,造成它的循环性能差,阻碍了实际应用。为了提高Ge负极材料的循环稳定性,研究者提出了纳米结构化和碳材料复合两种方法。具有不同相貌的纳米结构具有表面积大,离子/电子传输快的特点。而碳质材料具有高的导电性、好的机械柔韧性以及热和化学稳定性。在前人工作的基础上,本文开展了以下两方面的内容:(一)以市售的GeO_2、GO和纯水为原料,基于溶解-重结晶的机理制得了GeO_2/graphene复合物。复合物制备过程中所用的化学试剂和仪器无毒且便宜。用作LIBs负极材料进行性能测试时,结果表明:该电极具有好的循环性能和高的可逆容量:首次充电容量高达1637 mAh g~(-1),循环80圈后可逆容量保持在640mAh g~(-1)。(二)针对传统1 D纳米结构合成过程复杂、使用贵金属催化剂的缺点,本文通过静电纺丝的方法合成了Ge/CNFs。该材料表现出良好的储锂性能:在100mA g~(-1)的电流密度下,循环30圈后仍具有643.2 mAh g~(-1)的可逆容量,约为石墨负极的2倍。这主要归因于:(1)多孔结构能够增加电极与电解质的接触面积;(2)Li~+较短的扩散距离;(3)电子沿1 D方向快速传输,提高了电极的导电性。
[Abstract]:Li-ion battery as energy storage equipment has the characteristics of high energy density, high power, long life and friendly environment. However, the theoretical capacity of the LIBs graphite anode is only 372 mAh / g ~ (-1), which is difficult to meet the requirements of the establishment of energy storage system and the development of large electric vehicles. Negative electrode material is an important part of LIBs. Therefore, the development of high capacity anode material becomes the decisive factor to improve the performance of LIBs. As a cathode material for lithium-ion batteries, GE has the advantages of high specific capacity, low operating voltage and fast electron transfer rate, which is expected to replace graphite negative electrode. However, the volume expansion of GE in the process of circulation is serious, which results in its poor cycling performance and hinders its practical application. In order to improve the cyclic stability of GE anode materials, two methods of nanostructured and carbon composite were proposed. The nanostructures with different appearance are characterized by large surface area and fast ion / electron transport. Carbon materials have high electrical conductivity, good mechanical flexibility and thermal and chemical stability. On the basis of previous work, the following two aspects were carried out in this paper: (1) GeO_2/graphene complexes were prepared by using geo _ 2go and pure water as raw materials, based on the mechanism of solution-recrystallization. The chemical reagents and instruments used in the preparation of the complex are nontoxic and inexpensive. When used as LIBs anode material, the results show that the electrode has good cycling performance and high reversible capacity: the initial charge capacity is up to 1637 mAh / g ~ (-1) and the reversible capacity is kept at 640mAh ~ (-1) after 80 cycles. (2) in view of the complex synthesis process of traditional 1D nanostructure and the disadvantage of using noble metal catalyst, Ge- / CNFs were synthesized by electrospinning method in this paper. The material shows good lithium storage performance: at the current density of 100mA / GG ~ (-1), it still has a reversible capacity of 643.2 mAh / g ~ (-1) after 30 cycles, which is about 2 times as high as that of graphite negative electrode. This is mainly attributed to the fact that the porous structure can increase the contact area between the electrode and the electrolyte and increase the diffusion distance between the electrode and the electrolyte. The electron is transported rapidly along the direction of 1D and the conductivity of the electrode is improved.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33;TM912

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