锂离子电池硅基负极材料的制备与改性研究

发布时间：2018-07-10 13:56

本文选题：锂离子电池 + 硅基复合材料　；参考：《中南大学》2014年硕士论文

【摘要】：摘要：硅基材料具有非常高的理论容量及相对较低的脱嵌锂电位平台,被认为是最具潜力的高能量高性能的锂离子电池负极材料之一。本文就锂离子电池硅基负极材料的研究进展进行了详细综述,初步研究了硅单质的电化学性能。采用两种不同的方法分别制备了硅/石墨/碳复合材料和硅-石墨烯复合材料,并且分别研究了其结构形貌和电化学性能。初步考察了鳞片石墨及纳米硅的电化学性能,在50mAg-1下,纳米硅首次充放电容量高达1800.2mAh g-1和3483.6mAh g-1,20次之后的容量保持率为15.2%。鳞片石墨的首次充电容量为为345.8mAh g-1,首次放电容量为434.9mAh g-1,循环性能稳定且维持在370mAh g-1左右直至20次循环结束。以葡萄糖、纳米硅和鳞片石墨为原料,采用液相固化以及高温热解结合的方法法制备硅/石墨/碳复合材料(Si/G/C复合材料),考察了不同硅与鳞片石墨相对质量比对Si/G/C复合材料的结构及性能的影响。当纳米硅与鳞片石墨的质量之比为3：7时,Si30FG70复合材料的综合电化学性能最佳,首次充电比容量和放电比容量分别为733.6mAh g-1和1048.3mAh g-1,首次库伦效率为69.9%,20次之后的容量保持率为80.1%。以纳米硅和氧化石墨烯为原料,通过一种白组装的手段和水热还原的方法制备了硅-石墨烯复合材料。考察了不同氧化石墨烯水溶液浓度对材料电化学性能的影响,当石墨烯水溶液浓度为2mg/mL时,得到的Si-G-2复合材料循环性能最佳,首次充放电比容量分别为1123.3mAh g-1和2259.4mAh g-1.首次库伦效率为49.7%,50次之后的可逆比容量为871.1mAh g-1,容量保持率为77.5%。
[Abstract]:Abstract: Silicon based materials with very high theoretical capacity and relatively low deintercalated lithium potential platform are considered as one of the most promising high energy and high performance cathode materials for lithium ion batteries. In this paper, the research progress of silicon based anode materials for lithium ion batteries is reviewed in detail, and the electrochemical properties of silicon simple materials are preliminarily studied. Silicon / graphite / carbon composites and silicon-graphene composites were prepared by two different methods, and their structural morphology and electrochemical properties were studied. The electrochemical properties of flake graphite and nanocrystalline silicon were preliminarily investigated. The first charge and discharge capacity of nano-silicon was as high as 1800.2mAh g-1 and 3483.6mAh g-1 after 20 times of 1800.2mAh g ~ (-1) and the capacity retention rate was 15.2g ~ (-1) under 50mAg-1. The initial charging capacity of flake graphite is 345.8mAh g-1 and the initial discharge capacity is 434.9mAh g-1. The cyclic performance of flake graphite is stable and maintained at 370mAh g-1 until the end of 20 cycles. Using glucose, nano-silicon and flake graphite as raw materials, Silicon / graphite / carbon composites (Si / G / C composites) were prepared by liquid solidification and pyrolysis at high temperature. The effects of the relative mass ratio of silicon to flake graphite on the structure and properties of Si / G / C composites were investigated. When the mass ratio of nano-silicon to flake graphite is 3:7, the comprehensive electrochemical properties of Si30FG70 composite are the best. The first charge and discharge specific capacities are 733.6mAh g-1 and 1048.3mAh g-1, respectively, and the capacity retention of Si30FG70 composite is 80.1 after the first Coulomb efficiency is 69.9%. Silicon graphene composites were prepared by white assembly and hydrothermal reduction with nano-silicon and graphene oxide as raw materials. The effect of different concentration of graphene oxide solution on the electrochemical properties of the composite was investigated. When the concentration of graphene aqueous solution was 2 mg / mL, the cyclic performance of Si-G-2 composite was the best. The initial charge-discharge capacity of Si-G-2 composite was 1123.3mAh g-1 and 2259.4mAh g-1, respectively. After the first Coulomb efficiency of 49.7 and 50 times, the reversible specific capacity is 871.1mAh g-1, and the capacity retention is 77.5%.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912

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