论文总字数：29479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容量和性能提出了更高的要求。硅基材料因其具有容量大、储量多、电极电位合适等优点，在锂离子电池负极材料方面有着非常大的潜力。但硅负极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，不能满足大能量密度电池的需求。

本文结合硅的高容量和MXene的高导电性，制备了Si-Ti₃C₂T_X锂电复合负极材料。采用HCl LiF刻蚀Ti₃AlC₂制备出表面带有负电的Ti₃C₂T_X，用CTAB对纳米Si颗粒进行改性，使其表面带正电荷。运用静电自组装的思想，复合Si与Ti₃C₂T_X，采用絮凝和冷冻干燥法制得了Si-Ti₃C₂T_X复合材料，并对其进行表征和电化学性能测试。

实验结果表明：Si-Ti₃C₂T_X复合材料呈现三维多孔泡沫状，Si颗粒附着在Ti₃C₂T_X的片层上，而Ti₃C₂T_X片层相互堆叠搭建了良好的导电网络；复合材料的比表面积随着硅含量的上升而增大，硅含量为60%时，比表面积达到了46.39 m²/g，此时的平均孔径尺寸为15.3625 nm；电化学测试表明：复合电极的循环性能和倍率性能都优于纯Si负极，相比于Si含量为40%、60%的复合电极，Si含量为50%时，电极的电化学性能更好，经过200个循环后仍有596 mAh/g的容量，表明Ti₃C₂T_X缓解了硅的体积膨胀，阻止了硅的完全粉碎，多孔结构也更有利于锂离子的传导；循环伏安曲线电位重合度高，表明Si-Ti₃C₂T_X复合负极具有一定的循环稳定性；复合电极的电荷转移电阻比纯Si电极低，说明Ti₃C₂T_X改善了硅基材料导电率差的问题。

关键字：MXene 锂离子电池 硅 复合负极 电化学性能

Preparation, Characterization and Properties of Si-Ti₃C₂T_X 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 capacity and performance of lithium-ion batteries. Silicon-based materials have great potential in the negative materials of lithium-ion batteries due to their large capacity, large reserves and appropriate electrode potential. But the silicon anode has some problems such as volume effect. The new two-dimensional material MXene, represented by Ti₃C₂T_X, whose conductivity is more excellent, has larger surface area and better stability. It also has good performance in the negative electrode of lithium-ion batteries. However, the capacity of MXene as a lithium negative electrode is low, which can not meet the needs of high energy density batteries.

In this paper, Si-Ti₃C₂T_X composite lithium electronegative materials were prepared by combining the high capacity of silicon with the high conductivity of MXene. Ti₃C₂T_X with negative charge was prepared by etching Ti₃AlC₂ with HCL LiF. Using CTAB to modify the nano-Si particles , lead to the positive charge of nano-Si particles. Si-Ti₃C₂T_X composites were synthesized by electrostatic self-assembly, flocculation and freeze-drying method, and their characterization and electrochemical properties were tested.

The experimental results show that the Si-Ti₃C₂T_X composites show three-dimensional porous foams, Si particles adhere to the Ti₃C₂T_X lamellae, while the Ti₃C₂T_X lamellae stack up to form a good conductive network. When the silicon content of the composites is 60%, the area reaches 46.39 m²/g, and the average pore size is 15.3625 nm. The electrochemical tests show that the silicon content is 50% when the electricity is in 100mA/g. There is still a capacity of 596 mAh/g after 100 cycles. This is because Ti₃C₂T_X alleviates the volume expansion of silicon, prevents the side reaction between silicon and electrolyte, and improves the conductivity of silicon. The composition of silicon enhances the interlayer spacing of Ti₃C₂T_X, which is more conducive to the conduction of lithium ions. The high potential coincidence of cyclic voltammetry curve indicates that Si-Ti₃C₂T_X composite negative has cyclic stability, and the charge transfer resistance of composite electrode is much lower than that of pure Si electrode, which indicates that Ti₃C₂T_X improves the conductivity of silicon.

Key Words: MXene; Lithium-ion batteries; silicon; Composite Anode; electrochemical performance

目录

摘 要 I

Abstract II

第一章 绪论 1

1.1 引言 1

1.2 锂电子电池简介 1

1.2.1 锂离子电池的原理 1

1.2.2 锂离子电池的优缺点 2

1.3 锂离子电池负极材料 4

1.3.1 碳基负极材料的研究现状 4

1.3.2 非碳基负极材料的研究现状 5

1.3.3 硅基负极材料的研究现状 6

1.4 MXene的研究现状 7

1.4.1 MXene简介 7

1.4.2 MXene的制备 8

1.4.3 MXene的性质 10

1.4.4 MXene在储能领域的应用 11

1.5 立题依据与研究内容 13

第二章 实验方法 14

2.1 实验试剂 14

2.2 实验仪器 15

2.3 实验流程 16

2.3.1 Ti₃C₂T_x MXene的制备 16

2.3.2 三维Ti₃C₂T_x MXene泡沫的制备 16

2.3.3 Si-Ti₃C₂T_x复合泡沫的制备 17

2.4 材料表征 18

2.4.1 X射线衍射分析(XRD) 18

2.4.2 扫描电子显微分析(SEM) 18

2.4.3 透射电子显微分析(TEM) 18

2.4.4氮气吸脱附测试 18

2.5 电化学性能相关测试 18

2.5.1 复合电极的制备 18

2.5.2 扣式电池的组装 19

2.5.3 恒流充放电测试 19

2.5.4 循环伏安测试‌ 19

2.5.5 交流阻抗谱测试 20

第三章 实验结果与分析 21

3.1 Ti₃C₂T_x及三维Ti₃C₂T_x泡沫材料的表征与分析 21

3.1.1 Ti₃C₂T_x的表征 21

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