摘要：本文通过纳米球磨和喷雾干燥的方法合成出新型三元材料NCM811前驱体，然后采用氧气氛围下高温煅烧的方法制备LiNi0.8Co0.1Mn0.1O2正极材料，探究材料合成的最佳工艺路线。结果表明，当转速为900r/min，球磨时间为120min时，得到的前驱体材料粒径最小，为246nm；煅烧温度为500℃和800℃下分两段煅烧来获得结晶度最好的NCM811材料，经过阻抗分析得知Rb0%的锂离子扩散系数为3.33×10-11cm2·s-11。以上条件下得到的样品首次放电比容量为166.4mAh/g，经过100次循环后，其容量保持率为70.1%。然后根据最佳工艺来制备金属离子Rb掺杂的RbxLi(1-x)Ni0.8Co0.1Mn0.1O2正极材料，探究Rb离子掺杂对三元电极材料的结构和电化学性能的影响，当Rb掺杂量x=0.005时，经过阻抗分析得知Rb0.5%的锂离子扩散系数为1.14×10-10cm2·s-1，是Rb0％的3.42倍。由于锂离子扩散系数的增大有利于锂离子电池的放电比容量的增加，因此样品Rb0.5%在0.5C倍率下的首圈放电比容量达到了188.9 mAh/g，与样品Rb0％相比，提高了13.52％。100次充放电循环后Rb0.5%的容量保持率为88.9％，相比Rb0％提高了18.8％。

关键词：新型三元材料NCM811；正极材料；离子Rb掺杂；电化学性能

Preparation and Modification of NCM811 New type for electric vehicles Cathode Material for Lithium Battery

Abstract: Here we synthesized NCM811 precursor by nano ball milling and spray drying, then LiNi0.8Co0.1Mn0.1O2 cathode material is prepared by high-temperature calcination under oxygen atmosphere.Explore the best route for material synthesis.The result is: when the rotation speed is 900r/min and the milling time is 120min, the obtained precursor material has the smallest particle size of 246nm. Two-stage calcination at 500°C and 800°C yields the best crystallinity of NCM811 material.The Li+ ion diffusion coefficient calculated from EIS turn out a value of 3.33×10-11 cm2·s−1.The initial discharge capacity of the sample obtained under optimal conditions was 166.4 mAh/g. After 100 cycles, the capacity retention rate was 70.1%. The Rb-doped RbxLi(1-x)Ni0.8Co0.1Mn0.1O2 (x = 0, 0.005, 0.01, 0.02) cathode material was prepared by the same method according to the best process. We studied the influence of ion doping on the phase structure and electrochemical properties of the material and explored the optimal Rb doping amount. When x=0.005, that is sample Rb0.5%, the Li+ ion diffusion coefficient calculated from EIS turn out a value of 1.14×10-10 cm2·s−1, which is 3.42 times that of the non-doped sample. As the lithium ion diffusion coefficient increases, the discharge specific capacity of the lithium ion battery is increased. The initial discharge capacity at the 0.5C rate is 188.9 mAh/g, which is 13.52% higher than that of sample Rb0%. The capacity retention rate of Rb 0.5% is 88.9% after 100 cycles, which is 18.8% higher than Rb0%.

KeyWords:New type ternary material NCM811; cathode material; ion Rb doping; electrochemical performance

目录

1 绪论 1

1.1 引言 1

1.2 锂离子电池简介 1

1.2.1 锂离子电池发展状况 1

1.2.2 锂离子电池的结构和工作原理 1

1.2.3 锂离子电池正极材料 2

1.2.4 锂离子电池的正极材料LiNi0.8Co0.1Mn0.1O2的研究进展 2

1.2.5 LiNixCoyMnzO2结构和电化学性能 3

1.2.6 LiNi0.8Co0.1Mn0.1O2的制备方法 3

1.2.7 LiNi0.8Co0.1Mn0.1O2的改性研究 4

1.3 课题的主要内容 5

1.3.1 课题研究的目的和意义 5

1.3.2 论文研究内容 5

1.3.3 实施方案 5

2 实验部分 6

2.1 引言 6

2.2 实验原料 6

2.2.1 正极材料制备所需原料 6

2.2.2 组装电池所用原料 6

2.3 实验仪器 7

2.4 材料的制备及工艺流程图 7

2.5 正极极片的制备 8

2.6 电池组装 9

2.7 结构表征 9

2.7.1 热重-差示扫描量热法（TG-DSC） 9