论文总字数：20780字

摘 要

近年来，高能动力型锂离子电池发展迫切。开发高容量，安全可靠的新型负极材料成为锂离子电池发展亟待解决的问题。本文针对纯硅负极材料脱嵌锂的过程中严重的体积膨胀效应，拟选用硅碳复合材料作为研究对象，采用高温热解法对纳米硅粉与碳源进行复合包覆，制备硅碳复合材料，增强机械强度并改善体积膨胀效应。采用TEM表征纳米硅粉的粒度，采用XRD检测纳米硅粉及制备所得硅碳复合材料的相结构，采用SEM观察硅碳复合材料的微观结构；实验研究了纳米硅粉在去离子水中的分散工艺、硅粉对葡萄糖最大吸附量，并对组装成的电池进行了电化学性能的测试。本文获得如下主要结论：

（1）所采用的纳米硅粉为球形颗粒，颗粒尺寸细小而且均匀，其纯度达到99%以上；粒径主要分布在0-100nm之间，平均粒径为62.9nm。

（2）推荐纳米硅粉在去离子水中分散的最佳工艺参数为：在溶液pH=6时，加入3wt%的PEG2000分散剂，超声时间为60min，超声功率为560W。

（3）在葡萄糖浓度不断升高的情况下，硅粉对葡萄糖的吸附率不断升高，符合分子吸附理论。

（4）通过高温热解法制备的硅碳复合材料粉体的各个特征峰与硅和碳的特征峰相匹配，并且纳米硅较为均匀地镶嵌在碳材料中，而碳材料又紧密的镶嵌在一起。

（5）硅碳质量比为3:7的复合材料性能明显优于其他配比，在经过20个循环后，比容量和库伦效率都较高，具有很高的容量保有率。

关键词：锂离子电池；硅碳复合材料；纳米硅粉；制备及分散；电化学性能

Study on the Preparation of Silicon - carbon Composites and their Electrochemical Properties

ABSTRACT

In recent years, high-energy-powered lithium-ion battery development is urgent. Development of high-capacity, safe and reliable new negative materials become lithium ion battery development problems to be solved. In this paper, silica gel composites were selected as the research object, and the nano-silica powders and carbon source were coated with high temperature pyrolysis to prepare the silicon-carbon composites, for enhance mechanical strength and improve the volume expansion effect. The particle size of nano - silica powders was characterized by TEM，XRD was used to detect the phase structure of nano-silica particles and the prepared silicon-carbon composites, and the SEM was used to observe the micro- structure of silicon - carbon composites. The dispersion process of nanometer silicon powders in deionized water was studied experimentally. Silica gel on the maximum amount of glucose adsorption, and assembled into the battery electrochemical performance of the test. This paper obtains the following main conclusions:

(1) Nano-silica powders used in this paper is spherical particles, particle size is small and uniform, the purity of 99% or more; Particle size is mainly distributed between 0-100nm, the average particle size is 62.9nm.

(2) The optimum technological parameters for the dispersion of nano-silica powders in deionized water are as follows: when the solution pH = 6, 3wt% PEG2000 dispersant is added, the ultrasonic time is 60min, and the ultrasonic power is 560W.

(3) In the case of increasing glucose concentration, the adsorption rate of silicon powder on glucose is increasing, which accords with the theory of molecular adsorption.

(4) The characteristic peaks of the silicon-carbon composite powders prepared by high-temperature pyrolysis method are matched with the characteristic peaks of silicon and carbon, and the nanosilica is more evenly embedded in the carbon material, and the carbon material is closely embedded in the together.

(5) The properties of the composites with a silicon-to-carbon ratio of 3: 7 are significantly better than those of the other materials. After 20 cycles, the specific capacity and Coulomb efficiency are high and have a high capacity retention rate.

Keywords: Lithium-ion battery; Silicon-carbon composite material; Nanometer silica powders; Preparation and dispersion; Electrochemical Property

目 录

摘 要 I

ABSTRACT II

目 录 i

第一章 绪论 1

1.1引言 1

1.2 课题的研究背景 1

1.2.1锂离子电池负极材料 1

1.2.2锂离子非硅基电池负极材料研究概况 2

1.2.3锂离子电池硅基负极材料的研究进展 4

1.2.4硅碳复合材料的研究进展 5

第二章 研究目标、内容及方法 6

2.1 研究目标 6

2.2 研究内容 6

2.3实验药品与仪器 6

2.3.1实验药品 6

2.3.2实验仪器 7

2.4 研究方法 8

2.4.1纳米硅粉的表征及分散工艺研究 8

2.4.2葡萄糖最大吸附量测定 9

2.4.3硅碳复合材料的制备 9

2.4.4电极片的制备及电池组装 9

2.4.5电池电化学性能的测试 10

第三章 纳米硅粉表征及其分散工艺研究 11

3.1引言 11

3.2纳米硅粉的物相分析 11

3.2.1纳米硅粉的XRD分析 11

3.2.2纳米硅粉的TEM分析 11

3.2.3纳米硅粉的粒径分析 12

3.2.4硅粉-去离子水的pH-zeta电位图测定 12

3.3硅粉在去离子水中的超声分散工艺研究 13

3.3.1最佳超声分散时间的确定 13

3.3.2分散剂最佳添加量的确定 14

3.3.3最佳超声分散时间和最佳分散剂添加量下对纳米硅粉分散效果 15

3.4本章小结 16

第四章 硅碳复合材料的制备及其电化学性能 17

4.1引言 17

4.2纳米硅粉的葡萄糖最大吸附量测定 17

4.3硅碳复合材料的制备 18

4.4五组样品的电化学性能测试 20

第五章 结论与展望 23

5.1本文结论 23

5.2问题与展望 23

参考文献 25

致 谢 27

第一章 绪 论

1.1引言

近年来，随着世界经济的高速发展，人们对能源的需求日益增长。同时，环境污染和资源短缺的问题也越来越严重，开发清洁高效的新能源成为解决这一问题的关键。

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