论文总字数：27007字

摘 要

随着科技的进步和发展，人们对清洁可再生能源的需求越来越大。金属锂负极具有高的比能量、极低的电极电势，以及优秀的电化学反应可逆性等优点，成为构建锂金属电池理想的负极材料。然而在充放电循环过程中，锂负极表面易形成枝晶和“死锂”，导致循环效率降低和不可逆容量增大，严重时甚至可能引发内部短路。因此，抑制锂枝晶生长成为开发高性能锂金属负极的重要课题。

本文采用不锈钢网作为三维集流体，通过机械压制法制备了不锈钢网/金属锂（SSM/Li）复合材料，当组装成对称电池时，在电流密度为1mA/cm^-2时过电势稳定在85mV左右，而锂箔负极（Bare Li）稳定在521mV左右；当组装成全电池时，经过300次循环，SSM/Li比容量为128.7mAh/g，Bare Li仅为45.2mAh/g。而且，SEM分析表明SSM/Li的锂枝晶更细小，故SSM/Li的性能明显优于Bare Li。

为了进一步研究不锈钢网目数（60，150和300）对复合电极的影响，制备了SSM-60/Li、SSM-150/Li和SSM-300/Li三种复合负极。由全电池测试得，SSM-60/Li、SSM-150/Li和SSM-300/Li首次充放电容量分别为112mAh/g、71.8mAh/g和69.8mAh/g；由EIS分析得，SSM-60/Li的阻抗弧最小；由SEM分析得，SSM-60/Li表面的锂枝晶形貌细小且均匀。所以SSM-60/Li的性能优于SSM-150/Li和SSM-300/Li，由SEM分析可知，这是由于当网孔变小时，网格线划分的空间不足以容纳锂离子的沉积，迫使其在表面沉积，易造成锂枝晶生长，使得电池的性能降低。

关键词：不锈钢网，金属锂，复合负极，循坏性，安全性

ABSTRACT

With the progress and development of science and technology, people's demand for clean and renewable energy is increasing. Lithium metal anode has the advantages of high specific energy、low electrode potential and excellent reversibility of electrochemical reaction, which makes it an ideal anode material for lithium metal battery. However, during the cycle, dendrites and dead lithium are easy to form on the surface of lithium anode, leading to the reduction of cycle efficiency and the increase of irreversible capacity, and even the internal short-circuit may be caused in serious cases. Therefore, inhibiting the growth of lithium dendrites has become an important project to develop high performance lithium metal anode.

In this paper, stainless steel mesh was used as a three-dimensional current collector, and the composite material of stainless steel mesh/lithium metal (SSM/Li) was manufactured by mechanical pressing method. When the current density was 1mA/cm^-2 in symmetrical battery, the overpotential was about 85mV steadily, while Bare Li was 521mV. When assembled full battery, the specific capacity of SSM/Li was 128.7mAh/g while Bare Li was 45.2 mAh/g after 300 cycles. Moreover, SEM shows that the dendrites of SSM/Li are smaller, so the performance of SSM/Li is obviously better than Bare Li.

In order to further study the influence of stainless steel mesh number (60, 150 and 300) on composite electrode, three composite anode(SSM-60/Li, SSM-150/Li and SSM-300/Li) were manufactured. The first specific capacity of SSM-60/Li, SSM-150/Li and SSM-300/Li was 112mAh/g,71.8mAh/g and 69.8mAh/g, respectively. According to EIS, the impedance arc of SSM-60/Li is the smallest. Besides, the morphology of lithium dendrites on the surface of ssm-60/Li was smallest. Therefore, the performance of SSM-60/Li is better than that of SSM-150/Li and SSM-300/Li, this is because when the mesh becomes smaller, the space divided by the grid line is not enough to accommodate the deposition of lithium ions, forcing them to deposit on the surface, resulting in the growth of lithium dendrites and lowering the performance of the battery.

KEY WORDS: Stainless steel wire mesh, Lithium metal, Composite cathode, Cycle behavior, Security

目 录

摘 要 I

ABSTRACT II

第一章 绪论 1

1.1引言 1

1.2锂离子电池 1

1.2.1锂离子电池的工作原理 1

1.2.2 固体电解质膜 2

1.2.3锂枝晶的生长及问题 3

1.3金属锂负极常用的改性方法 4

1.3.1电解质改性 4

1.3.2人工SEI膜 5

1.3.3合金化 5

1.3.4 表面处理 6

1.2.5三维集流体 6

1.4本文的研究目的和主要研究内容 8

第二章 实验设备及方法 9

2.1 实验材料及仪器 9

2.1.1 实验材料 9

2.1.2 实验仪器 9

2.2 正负极材料的制备 9

2.3扣式电池的组装 10

2.4锂离子电池的性能 11

2.4.1蓝电测试 11

2.4.2电化学阻抗谱技术 12

2.4.3物理形貌 13

2.5本章小结 14

第三章 不锈钢/金属锂复合负极与锂箔负极的对比 15

3.1引言 15

3.2电化学性能测试 15

3.2.1恒流充放电电测试 15

3.2.2倍率测试 17

3.2.3全电池测试 17

3.3 形貌表征 18

3.4本章小结 19

第四章 网孔大小对不锈钢/金属锂复合负极性能的影响 20

4.1引言 20

4.2 电化学性能测试 20

4.2.1恒流充放电电测试 20

4.2.2倍率测试 22

4.3.3全电池测试 23

4.3.3电化学阻抗分析 24

4.3 形貌表征 25

4.4本章小结 26

结论与展望 28

致 谢 29

参考文献 30

第一章 绪论

1.1引言

自1860年干电池的出现开始，电池储能技术不断发展，但是干电池都是一次性电池，用完之后不能充电，对环境的污染十分严重。随着人类社会的进步和科技的发展，对绿色高效的新能源和储能技术需求越来越大，高效的能源存储和转换可以方便人们高效的利用能源。近年来，电子行业对新型储能技术的市场需求越来越大，这促进了电子行业发展迅速，电子设备向小型化、便携化发展。现在的锂电池容量不断增大、质量减轻、体积变小、成本降低、性能稳定，成为许多电子设备的首选。锂离子电池广泛应用于各个领域，生活方面有智能手机、笔记本电脑、相机等；国防方面有GPS定位系统、导弹、雷达等。

目前商业化的锂离子电池负极材料主要是石墨等碳类材料，然而石墨的理论比容量仅为372mAh/g^[1]，而且石墨负极在第一次充放电循环过程中会产生较多的不可逆容量,这些因素都使得以石墨为负极材料的锂电池难以满足新能源技术对高能量密度二次电池的需求。此外，若以硅、锡等作为负极材料，在充放电过程中它们会与金属锂反应形成含锂化合物来存储和脱出锂离子，这将导致电极体积发生剧烈变化，引起负极材料的粉化或从集流体上剥离，使电池容量明显下降，最后会导致电池失效^[2]。

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