中空多孔结构材料的制备及其电化学储锂性能

发布时间：2018-01-19 10:07

本文关键词： 锂离子电池过渡金属氧化物合金型材料中空或多孔电化学储锂性能　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：现今社会,能源和环境问题日益突出,随着各种化学能源的不断发展,锂离子电池从中凸显了其巨大的价值和优势,得到广泛的认可。过渡金属氧化物以及部分合金型材料因为具有储锂性能优异、成本低廉、环境友好和资源丰富等优点,受到研究人员的广泛关注。但是,它们较低的电导率以及较差的电化学循环稳定性制约了其产业化应用。针对这些问题,本文制备了具有中空或多孔结构的材料,并对其结构和电化学储锂性能进行了表征。通过简单的溶剂热反应,随后在氩气保护下热处理的方法制备了具有中空结构的Mn_xFe_((3-x))O_4材料。通过XRD、Raman、AAS、SEM和TEM等测试方法对Mn_xFe_((3-x))O_4材料的物相和微结构进行了表征。该材料表现出优异的储锂性能。在0.2 A·g~(-1)的电流密度下,循环100圈以后的容量为1130 mAh·g~(-1);在电流密度为0.2、0.5、1、2和3 A·g~(-1)时,可逆容量分别为970、710、578、461和377 mAh·g~(-1)。这主要得益于材料独特的中空结构以及表面纳米片化,提供了更大的比表面积,增加了活性物质与电解液的接触。另外,这样的中空结构的构建,有利于减缓充放电过程中材料的体积变化,从而提高材料的电化学循环稳定性。在此基础上,还研究了水含量与葡萄糖添加量对Mn_xFe_((3-x))O_4材料结构的影响。随着水含量的增加,空心结构更明显；溶剂中葡萄糖的加入,会使得形成的中空材料的表面变得更加致密,这导致材料比表面积的降低,进而引起电池容量的下降。以硅铝粉作为原材料,通过简单溶剂热方法,利用铝离子与对萘二甲酸的配合作用形成配合物,从而获得具有核壳结构的前驱物,进一步通过在氩气中煅烧和酸蚀刻制备了多孔硅基核壳材料。该方法可以对不规则的原材料进行修饰,获得规则的多孔核壳结构材料。该材料独特的多孔核壳结构,提供了较大的电化学活性比表面积,有利于锂离子在材料中的传输,从而提高了材料的储锂性能；同时多孔核壳结构能够缓冲材料嵌锂/脱锂引起的巨大体积变化,使得该材料表现出优异的倍率性能以及循环稳定性。
[Abstract]:Nowadays, energy and environmental issues have become increasingly prominent, with the continuous development of a variety of chemical energy, lithium ion battery has highlighted its great value and advantage in widely recognized. The transition metal oxide and alloy type material because of its excellent lithium storage performance, low cost, friendly environment and the advantages of rich resources, by the attention of researchers. However, their low conductivity and poor electrochemical cycle stability limits its industrial applications. To solve these problems, with a hollow or porous structure materials were synthesized, and the structure and electrochemical properties of lithium storage were investigated. Through simple solvothermal reaction, with a hollow the structure of Mn_xFe_ was prepared after heat treatment in argon ((3-x)) O_4. Through XRD, Raman, AAS, SEM and TEM test method for Mn_xFe_ ((3-x)) O_4. The phase and microstructure were investigated. The material exhibits excellent lithium storage performance. In 0.2 A - g~ (-1) of the current density, capacity after 100 cycles of 1130 mAh - g~ (-1); when the current density is 0.2,0.5,1,2 and 3 A g~ (-1), reversible capacity are 970710578461 and 377 mAh g~ (-1). This is mainly due to the unique hollow structure materials and surface nano film, provides greater specific surface area and increase the active material and the electrolyte contact. In addition, constructing such a hollow structure, is conducive to slow down the process of charge and discharge volume change materials in, so as to improve the electrochemical cycle stability of the material. On this basis, but also on the water content and glucose addition on Mn_xFe_ ((3-x)) O_4 material structure. With the increase of water content, the hollow structure is more obvious; glucose added to the solvent, makes the formation of hollow The surface of the material becomes more dense, which leads to the surface area of the material is reduced, thereby causing a decline in battery capacity. The aluminium silicon powder as raw materials, through a simple solvothermal method, using aluminum ion and complexation of naphthalene two formic acid complexes formed so as to obtain the precursor with core-shell structure, further through porous silica core-shell materials were prepared in argon calcination and acid etching method. The raw materials can be modified for the irregular, irregular porous core-shell materials. Porous core-shell structure of the material provides a unique and electrochemical activity of large surface area, is conducive to the transmission of lithium ion in the material. The improved lithium storage materials; at the same time, the porous shell structure can buffer material of lithium intercalation / deintercalation of the huge volume change, so that the material exhibits excellent rate capability and cycle stability .

【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.4

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