论文总字数：23823字

摘 要

锂离子电池（LIBs）的研究一直是近年来的热门领域，然而相关电极材料的性能快要接近极限。随着正极材料的开发达到研究热潮，研究者们追逐更完美电池性能的脚步从未停歇，开发具有高容量且循环稳定的长效负极材料已是势在必得。硫化锰具有三种晶型，绿色的α-MnS、粉色的β-MnS和γ-MnS。根据电化学锂化过程中吉布斯自由能变化 -202.5 kJ·mol^-1以及1.049 V的电动势，可知岩盐结构的硫化锰（α-MnS）具有较高的锂储存容量，且具有生态友好性和良好的成本效益，但致命的缺点就是充放电循环时的体积膨胀会大大降低循环稳定性。为了改善这一问题，较为有效的方法是构建掺杂碳的纳米复合材料，不仅可以有效地抑制形成的多硫化物的溶解，还可以提高导电性，缩短离子迁移率的路径，从而实现长期循环稳定性和高能量密度。

本课题为了改善锂离子电池中α-MnS负极的电化学性能，设计基于碳布原位自支撑的α-MnS用作锂离子电池负极并测试其性能。本文通过X射线衍射分析、扫描透射电子显微镜观察样品微观形貌和相组成，并对样品进行一系列电化学性能测试。通过水热反应和多巴胺包覆获得还原MnO@C，再与S粉在高温Ar条件下反应得到目标产物纯相的α-MnS。纳米材料以其独特的结构优势，是构建多维多功能电化学储能电极结构的理想构件，本课题制备获得的掺杂C基纳米材料，具有良好的电化学可逆性，在0.1 A·g^-1的电流密度下α-MnS@C电池做放电/充电循环测试，得到的初始的库仑效率为86％，随后第二个循环和第五个循环的库仑效应都接近于90%，与CV曲线结果相对应，这样的高库仑效应表明了电池具有良好的可逆性。但在放电/充电循环测试中表现出较差的循环稳定性，α-MnS@C电极的初始放电容量约为590 mAh·g^-1，至第38个循环仍然能够保持570 mAh·g^-1的容量，之后容量出现明显衰减，在第77次循环开始容量稳定率稍有提升，但是对于改善电极材料循环稳定性的效果还有待提升。

关键词：锂离子电池 α-MnS 复合碳基纳米材料

In-situ self-supporting manganese sulfide as lithium ion battery anode

Abstract

The research of lithium ion batteries (LIBs) has been a hot field in recent years, but the performance of related electrode materials is approaching the limit. As the development of cathode materials has reached a research boom, researchers have never stopped to pursue a more perfect battery performance. It is indispensable to find out long-acting anode materials which have high capacity and stable circulation. Manganese sulphide has three crystal forms, green α-MnS, pink β-MnS and γ-MnS. According to the electromotive force of Gibbs free energy change of -202.5 kJ·mol^-1 and 1.049 V during electrochemical lithiation, it is known that the rock salt structure of manganese sulfide (α-MnS) has high lithium storage capacity, and is eco-friendly and good. The cost-effective, but fatal disadvantage is that the volume expansion during the charge and discharge cycle will greatly reduce the cycle stability. In order to improve this problem, a more effective method is to construct a carbon-doped nanocomposite, which can not only effectively inhibit the formation of polysulfide, but also improve conductivity and shorten the path of ion mobility, thereby achieving long-term circulation. Stability and high energy density.

In order to improve the electrochemical performance of α-MnS anode in lithium ion battery, α-MnS based on in-situ self-supporting carbon cloth was designed as the negative electrode of lithium ion battery and its performance was tested. In this paper, the microstructure and phase composition of the sample were observed by X-ray diffraction analysis and scanning electron microscopy, and a series of electrochemical performance tests were carried out on the sample. The reduced MnO@C is obtained by hydrothermal reaction and dopamine coating, and then reacted with the S powder under high temperature Ar conditions to obtain α-MnS of the pure phase of the target product. Nanomaterials, with its unique structural advantages, are ideal components for constructing multi-dimensional multifunctional electrochemical energy storage electrode structures. The doped C-based nanomaterials prepared by this subject have good electrochemical reversibility, and α-MnS@C The electrode was subjected to a discharge/charge cycle test at a current density of 0.1 A·g ^-1 with an initial coulombic efficiency of 86%, followed by a Coulomb effect of both the second cycle and the fifth cycle being close to 90%, with CV curve results. Correspondingly, such a high Coulomb effect indicates that the battery has good reversibility. However, it exhibited poor cycle stability in the discharge/charge cycle test. The initial discharge capacity of the α-MnS @ C electrode was about 590 mAh·g^-1 , and the capacity of 570 mAh·g^-1 was still maintained until the 38th cycle. After that, the capacity showed a significant attenuation, and the capacity stability rate increased slightly at the 77^th cycle, but the effect of improving the cycle stability of the electrode material needs to be improved.

Key Words: Lithium-ion Battery；α-MnS；Composite carbon-based nanomateria

目 录

摘要 I

ABSTRACT II

第一章 绪论 1

1.1 引言 1

1.2锂离子电池介绍 2

1.3锂离子电池电极材料 3

1.3.1 锂离子电池正极材料 3

1.3.2 锂离子电池负极材料 5

1.4二元金属硫化物 6

1.4.1 硫化物作为电极材料的研究现状 6

1.4.2 常见二元硫化物电极材料的性能 8

1.4.3硫化锰材料 8

1.4.4 硫化锰材料用作锂离子电极的研究现状 9

1.5本文的研究意义 10

第二章 实验方法 11

2.1 实验原料与试剂 11

2.2 实验设备与仪器 11

2.3 材料的制备 12

2.4 实验微观分析及表征 13

2.5 电化学性能分析 14

第三章 实验数据与结果讨论 16

3.1 实验形貌分析 16

3.2 实验电化学性能分析 16

第四章 结论与展望 19

4.1 主要结论 19

4.2展望 20

参考文献 21

致谢 24

绪论

引言

二十一世纪，人类社会的经济不断繁荣、科技不断发展、人口数量不断上升，对能源的使用也愈加频繁。预计到下个世纪中叶，人类对能源的需求将会翻倍。目前，人类社会接近百分之九十的能源来自化石燃料的使用^[1]，由于耗尽的传统化石燃料的需求日益增长，锂离子电池（LIBs）因其可逆性和无污染气体排放而成为处理能源困境和严重温室效应的紧迫因素的相当有前景的能源之一。近年来微型能源提供装置在随身设备、电力驱动汽车、智慧型手机等设备中被广泛采用，是一种高效能的新型功能媒介。如：为了提高能量源的利用百分比，可以将其作为能量源的仓储装置，作为新颖能源汽车的能量供给装置已完全消灭污染尾气的排放问题。而电能是当前人类社会的大趋势，则微型能量供给装置（如电池）的发展也深深左右着社会进程的大趋势。

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