论文总字数：25639字

摘 要

随着电动汽车、便携式电子设备的不断革新，人们对于锂离子电池的能量密度和循环寿命提出了更高的要求。硅材料因其理论比容量大、储量丰富、电极电位合适等优势，在用作锂离子电池负极材料方面有着非常大的潜力。但硅负极材料在充放电过程中却面临着体积膨胀巨大，导电性差等问题。以Ti₃C₂T_X为代表的新型二维材料MXene具有优异的导电性、大的比表面积和良好的稳定性，其在锂离子电池负极方面也有很好的表现。然而MXene作为锂电负极时的容量较低，并且容易发生层间堆垛。

本文将纳米硅颗粒与二维Ti₃C₂T_X纳米片复合，添加力学性能和导电性能优异的一维碳纳米管，制备三维多孔泡沫。该结构能有效缓解硅体积膨胀、抑制Ti₃C₂T_X纳米片层间堆垛，构建三维导电网络，有利于电解液的渗透，促进电荷传输。采用HCL LiF刻蚀Ti₃AlC₂，通过手摇剥离、离心制备出表面带有负电的单/少层Ti₃C₂T_X墨汁，再添加Si、改性后的CNT，通过HCl诱导静电自组装得到水凝胶，最后经过冷冻干燥制得Ti₃C₂T_X-CNT/SiNP复合泡沫，并对其进行表征和电化学性能测试。

结果表明：Ti₃C₂T_X-CNT/SiNP复合材料呈现三维多孔结构，且孔隙发达、均匀，Ti₃C₂T_X片层发生褶皱，Si颗粒附着在Ti₃C₂T_X片上和碳纳米管表面。硅含量为60%，电流密度为200 mA/g时，复合泡沫经过100个循环后仍有520 mAh/g的容量。因此，Ti₃C₂T_X-CNT/SiNP复合材料作为锂离子电池负极材料具有优异的电化学性能。结合相关文献预测：硅含量为50%，电极活性物质涂覆厚度为50 μm时，电池倍率性能和循环性能更佳。

关键字：MXene 硅 碳纳米管 锂离子电池复合负极 电化学性能

Preparation and Properties of Ti₃C₂T_X-CNT/SiNP Composite Anode for Lithium-ion Battery

Abstract

With the continuous innovation of electric vehicles and portable electronic devices, people put forward higher requirements for the energy density and cycle life of lithium ion batteries. Silicon materials have great potential in anode for lithium-ion batteries due to their advantages such as large theoretical specific capacity, abundant reserves, and suitable electrode potential. However, silicon anode materials face problems such as huge volume expansion and poor conductivity during charging and discharging. The new two-dimensional material MXene, represented by Ti₃C₂T_X, has excellent conductivity, large surface area and good stability. Thus it has a good performance in the negative electrode of lithium-ion batteries. However, MXene has a relatively low capacity as an anode and easily occur stack between layers.

In this paper, nanometer silicon particles are combined with two-dimensional Ti₃C₂T_X nanosheets, and one-dimensional carbon nanotubes with excellent mechanical properties and electrical conductivity are added to prepare three-dimensional porous foam. The structure can effectively relieve the volume expansion of silicon, inhibit the stacking of nanosheets, and build a three-dimensional conductive network, which is conducive to the penetration of electrolyte and promotes the charge transfer. Using HCL LiF to etch Ti₃C₂T_X, prepare single/few layers of Ti₃C₂T_X ink with negative charge on the surface by hand peeling and centrifugation, then add Si and modified CNT, and induce hydrostatic self-assembly through HCl to obtain a hydrogel. After freeze-drying, Ti₃C₂T_X-CNT/SiNP composite foam was prepared and characterized and tested for electrochemical performance.

The results show that the composite exhibits a three-dimensional porous structure with well-developed and uniform pores. The Ti₃C₂T_X nanosheets are wrinkled, and Si particles are attached to the Ti₃C₂T_X sheet and the surface of the carbon nanotubes. When the silicon content is 60% and the current density is 200 mA/g, the composite foam still has a capacity of 520 mAh/g after 100 cycles. Therefore, Ti3C2TX-CNT/SiNP composite material has excellent electrochemical performance as a negative electrode material for lithium ion batteries. According to related references, it is predicted that when the silicon content is 50% and the electrode active material coating thickness is 50 μm, the battery rate performance and cycle performance are better.

Key Words: MXene; silicon; CNT; Lithium-ion battery composite Anode; electrochemical performance;

目录

摘要 I

Abstract II

第一章 绪论 1

1.1引言 1

1.2锂离子电池概况 1

1.2.1锂离子电池工作原理 2

1.2.2锂离子电池性能 2

1.3锂离子电池负极材料性能要求和种类 3

1.3.1 碳材料 4

1.3.2 非碳材料 4

1.4硅基锂离子电池负极材料简介 5

1.5 MXene材料的研究现状 7

1.5.1 MXene简介 7

1.5.2 MXene性能 8

1.5.3 MXene的应用 8

1.6 MXene在锂离子电池负极材料的应用 10

1.7立题依据与研究内容 11

第二章 实验方法 12

2.1 实验试剂 12

2.2 实验仪器 13

2.3 实验步骤 14

2.3.1 Ti₃C₂T_x MXene的制备 14

2.3.2三维Ti₃C₂T_x MXene泡沫的制备 15

2.3.3 Ti₃C₂T_x-CNT/SiNP复合泡沫制备 15

2.4 材料表征 15

2.4.1 X射线衍射分析（XRD） 15

2.4.2扫描电子显微分析（SEM） 15

2.4.3透射电子显分析(TEM) 15

2.5 电化学性能相关测试 16

2.5.1复合电极制备 16

2.5.2扣式电池的组装 16

2.5.3恒流充放电测试 17

2.5.4循环伏安测试 17

2.5.5交流阻抗谱测试 17

第三章 结果与讨论 18

3.1 Ti₃C₂T_x及三维Ti₃C₂T_x泡沫材料的表征与分析 18

3.1.1 Ti₃C₂T_x表征与分析 18

3.1.2 三维Ti₃C₂T_x泡沫材料的表征与分析 19

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