论文总字数：22136字

摘 要

开发高容量负极材料是提升锂离子电池能量密度的关键之一。氧化铁材料与已应用于锂离子电池的石墨（372 mAhg^-1）负极材料相比，具有高的理论容量（Fe₂O₃，1007 mAhg^-1），而且无毒性且在自然界的储量丰富。但是以纯的氧化铁作为负极材料，在充放电的过程中会引起剧烈的体积变化、严重破坏负极的稳定性。碳可以用于具有过渡金属氧化物的复合材料中以改善其电化学性能，因为纳米碳不仅可以提供用于降低的反应电阻的高导电性基体，而且还可以提供缓冲层以解决充放电所引起的高体积变化，降低在循环期间活性颗粒团聚。

本文以热分解法制得的FeOCl材料作为制备氧化铁的前驱体，通过吡咯插层FeOCl及随后的热处理来制备氧化铁/碳纳米复合材料。采用X-射线衍射来表征材料的结构，并测试所得材料的充放电性能。主要研究结果如下：

（1）在220 ℃、1 h条件制得了纯相FeOCl材料；随后将FeOCl和吡咯单体混合，在50 ℃的温度条件下，反应2天可获得几乎被聚吡咯完全插层的FeOCl/PPy复合材料；而进一步延长插层时间，会导致FeOCl分解，直接生成Fe₂O₃/PPy复合材料；

（2）热处理结果表明，Fe₂O₃/PPy复合材料经350 ℃处理后，产物主相为Fe₃O₄，说明Fe₂O₃被PPy热分解产生的碳还原；而经600 ℃高温处理后，碳还原反应更加剧烈，产物主相为Fe₃O₄和Fe₃C；

（3）充放电测试结果表明，低温热处理获得的氧化铁/碳复合材料的放电容量为1950mAhg^-1；高温热处理的为1260mAhg^-1。低温热处理的结果更好，可能是由于经过低温热处理后的颗粒细小。

关键字：锂离子电池、FeOCl、氧化铁/碳纳米复合材料、负极

Preparation of Iron Oxide/Carbon Nanocomposite Anode Material and Study on Its Lithium Storage Properties

Abstract

The development of high-capacity anode materials is one of the keys to improving the energy density of lithium-ion batteries. Iron oxide materials have a higher theoretical capacity (Fe₂O₃, 1007 mAhg^-1) than graphite (372 mAhg^-1) anode materials that have been used in lithium ion batteries, and are non-toxic and abundant in natural reserves. However, pure iron oxide is used as a negative electrode material, which causes a drastic volume change and severely destroys the stability of the negative electrode during charge and discharge. Carbon can be used in a composite material having a transition metal oxide to improve its electrochemical performance because nanocarbon can not only provide a highly conductive matrix for reduced reaction resistance, but also can provide a buffer layer to solve the problem of charge and discharge. The high volume change reduces active particle agglomeration during cycling.

In this paper, FeOCl materials prepared by thermal decomposition method were used as precursors for preparing iron oxides, and iron oxide/carbon nanocomposites were prepared through polypyrrole intercalation of FeOCl and subsequent heat treatment. X-ray diffraction was used to characterize the structure of the material and the resulting material was tested for its charge and discharge properties. The main findings are as follows:

1. Pure phase FeOCl material was obtained at 220 °C for 1h. FeOCl and pyrrole monomers were then mixed. At 50°C, FeOCl/PPy composites almost completely intercalated with polypyrrole were obtained after 2 days of reaction. Further prolonging the intercalation time will lead to decomposition of FeOCl and direct formation of Fe₂O₃/PPy composites;
2. The results of heat treatment showed that the main phase of Fe₂O₃/PPy composites was Fe3O4 after treatment at 350°C, which indicated that Fe₂O₃ was reduced by the pyrolysis of PPy. After carbon treatment at 600°C, the carbon reduction reaction was more severe. The main phase of the product was Fe₃O₄ and Fe₃C;
3. The charge and discharge test results show that the discharge capacity of the iron oxide/carbon composite material obtained by the low temperature heat treatment is 1950mAhg^-1, and that of the high temperature heat treatment is 1260mAhg^-1. The better the low-temperature heat treatment may be due to the fine particles after the low-temperature heat treatment.

Key words: Lithium ion battery; FeOCl; iron oxide/carbon nanocomposites; negative electrode

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1 引言 1

1.2 锂电池简介及工作原理 1

1.3 负极材料 2

1.3.1 负极材料特征 2

1.3.2 铁氧化物负极材料 3

1.3.3 铁氧化物负极材料的缺点及其改善方法 5

1.3.4 铁氧化物锂离子电池负极材料的制备方法 7

1.4 本文的研究内容及意义 8

第二章 实验部分 9

2.1 实验仪器及主要原料 9

2.1.1 实验主要仪器 9

2.1.2 实验主要原料 9

2.2 实验流程 10

2.3 实验方案原理 11

2.3.1 FeOCl材料的简介及制备 11

2.3.2 吡咯（插层物）简介及其插层机理 11

2.4 材料表征 12

2.4.1 X射线衍射（XRD） 12

2.4.2 扫描电镜（SEM） 12

2.5 电化学性能测试 13

2.5.1 充放电循环性能测试 13

2.5.2 循环伏安法测试（CV） 13

第三章 实验结果及分析 14

3.1 材料表征测试与分析 14

3.2 电化学性能测试与分析 18

第四章 结论 21

参考文献 22

致 谢 25

第一章 绪论

1.1 引言

现代社会在高速发展的同时科学技术也在不断的进步，但是随着两者不断发展的同时也伴随着一次性能源的消耗也是越来越多，这也导致了其全球储量的日益降低，最终将无法满足人们的日常需求，于是洁净、环保、污染小的二次能源越发受到人们的广泛关注。^[1]在现有的各种二次电池中，可以进行二次充电锂电池（LIBs）由于其本事的能量密度较高，可使用的寿命较长，因此被用在了很多不同的电子设备上，包括手机、数码相机和插入式混合动力电动汽车等高功率应用。^[2-5]石墨目前是锂电池的主要负极材料，因为其在自然界中的储量很多从而价格便宜。不幸的是，低理论比容量（372mAhg^-1）和速率性能不能满足日益增长的要求。^[6]根据以上介绍可知，石墨的低容量已经满足不了现如今的二次电池要求，因此寻找高容量更加优质的材料是现如今的重要研究方向之一。

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