固相法合成具有纳米尺寸的Li2CrxMn1-xSiO4/C正极材料及其电化学性能的表征
毕业论文关键词： 硅酸锰锂；充放电性能；XRD；铬
Abstract Li2MnSiO4 anode materials were synthesized by high-temperature solid-phase method. The influence of different synthetic temperatures, carbon-coating, different contents of Cr doping and Li on the size distribution, charge-discharge capacity and cyclic performance of Li2MnSiO4 were investigated. Through the phase analysis of Li2MnSiO4 samples by XRD, orthorhombic Li2MnSiO4 (O-Li2MnSiO4)sample was obtained at 700℃, which transfers to monoclinic Li2MnSiO4 (M-Li2MnSiO4) when the synthetic temperature increases to 750℃. The initial specific discharge capacity (31 mAhg-1) and the capacity retention of the O-Li2MnSiO4 sample is better than that of the M-Li2MnSiO4. Coating O-Li2MnSiO4 with carbon (O-Li2MnSiO4/C) drives the initial discharge specific capacity increasing to 43mAhg-1. When the O-Li2MnSiO4/C was doped with varied Cr content from 0 to 0.1, the Li2Cr0.05Mn0.95SiO4/C has the highest initial discharge capacity (90.1 mAhg-1). A 10% Li excess Li2Cr0.05Mn0.95SiO4/C sample has an improved initial discharge specific capacity (138.9 mAhg-1) than that of both the 5% Li excess Li2Cr0.05Mn0.95SiO4/C and no Li excess Li2Cr0.05Mn0.95SiO4/C samples.
Keywords: Manganese lithium silicate；Charge and discharge property；XRD；Chromium
目录
1 绪论 1
1.1 锂离子电池的简介 1
1.1.1 锂离子电池的发展现状 1
1.1.2 锂离子电池的工作原理 2
1.1.3 Li2MSiO4的结构特点 3
1.1.4 Li2MSiO4的制备方法 5
1.1.5 Li2MnSiO4存在的问题及改进方法 7
1.2 课题内容 8
1.2.1 课题研究的目的和意义 8
1.2.2 课题研究内容 8
1.2.3 研究方案 8
2 实验内容 10
2.1 实验原料 10
2.2 实验仪器和设备 10
2.3 Li2CrxMn1-xSiO4/C正极材料的制备 11
2.3.1 原料的预处理 11
2.3.2样品的制备 11
2.3.3 电极片的制作 12
2.3.4 扣式电池的组装 12
2.4 实验研究的方法 12
2.4.1 X射线衍射法物相分析 12
2.4.2充放电性能测试法 12
3 实验结果和分析 13
3.1 物理性能表征 13
3.1.1 不同温度对Li2MnSiO4的影响 13
3.1.2 碳包覆对O-Li2MnSiO4的影响 16
3.1.3 不同Cr含量取代对O-Li2MnSiO4/C的影响 17
3.1.4 Li过量对Li2Cr0.05Mn0.95SiO4/C的影响 25
4.实验结论 29
致谢 30
参考文献 31
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