锂离子电池自支撑一维多孔碳与硅碳复合负极材料研究

发布时间：2018-01-12 13:02

本文关键词：锂离子电池自支撑一维多孔碳与硅碳复合负极材料研究　出处：《清华大学》2014年博士论文　论文类型：学位论文

【摘要】：随着锂离子电池逐渐广泛使用于动力、储能等大容量、高功率电池领域，锂离子电池的能量密度、功率密度、使用寿命、安全性和成本成为最重要的因素。而高性能负极材料的研发是解决这些问题的关键之一。本文以碳基和非碳基负极材料中颇具潜力的一维多孔碳负极和一维硅碳复合负极材料为研究对象，通过变换碳前驱体、掺氮和材料微观结构设计等方法提高了其电化学性能，同时也揭示了性能提升的原因和内在机制。论文中，选取聚酰亚胺为碳前驱体，，以原位生成SiO2纳米颗粒为牺牲模板，通过电纺丝、热处理和后续的化学处理等方法，首次制备了一种适用于锂离子电池的，具有自支撑结构的聚酰亚胺基一维多孔碳负极材料。相比较聚丙烯腈基一维多孔碳负极材料，聚酰亚胺基一维多孔碳负极材料具有高的比表面积、较好的微孔结构和更为优异的电化学性能。这主要同聚酰亚胺基多孔碳纤维所具有的独特的微孔结构、大的比表面积有关。在碳材料中掺杂氮等异质元素，可起到调控碳材料的性质，提高碳材料电化学性能的目的。在聚丙烯腈中掺入富氮物质——三聚氰胺，通过电纺丝、碳化和活化的方法，首次制备了一种具有自支撑结构锂离子电池用一维掺氮多孔碳负极材料，并同时研究了不同掺氮量和活化造孔方式对一维掺氮多孔碳负极材料结构和电化学性能的影响规律。发现，氨气处理所获得的一维掺氮多孔碳负极材料具有较好的纤维形态、高的掺氮量和良好的微孔结构。同时，此自支撑一维掺氮多孔碳负极材料具有优异的电化学性能。其容量超高，达到1323mAh g-1，是目前所报道的碳基负极材料的容量最高值。且其循环性能和倍率性能也非常优异。究其原因，这同此材料具有独特的微孔结构、高的氮含量、一维纳米结构和含有高于目前文献所报道的大量的吡啶氮有关。 Si具有最高的理论容量（4200mAh g-1）。但因充放电过程中Si有~400%的体积变化导致Si基负极材料循环性能差，严重制约了其实际应用。本文中，以纳米硅粉、聚乙烯醇和酚醛树脂为原料，利用电纺丝、溶液浸渍和热处理的方法，较为简单、经济和安全地得到了具有一定预置空间的锂离子电池自支撑一维硅碳复合负极材料。通过控制浸渍溶液浓度这一简单、有效的办法，调节一维Si/C复合负极材料硅、碳含量和微观结构，获得了优异的电化学性能。
[Abstract]:With the lithium ion battery widely used in power, energy storage and other large capacity, high power battery field, lithium ion battery energy density, power density, service life. Safety and cost are the most important factors, and the research and development of high performance anode materials is one of the key to solve these problems. In this paper, the potential one-dimensional porous carbon anode and one-dimensional silicon carbon in carbon-based and non-carbon-based anode materials are discussed. Composite negative electrode material is the object of study. The electrochemical performance of carbon precursor, nitrogen-doped material and microstructure design were improved, and the reason and mechanism of performance improvement were also revealed. In this paper, polyimide was selected as carbon precursor and SiO2 nanoparticles were prepared as sacrificial template by electrospinning, heat treatment and subsequent chemical treatment. A polyimide based one-dimensional porous carbon anode material with self-supporting structure for lithium-ion batteries was prepared for the first time, and compared with polyacrylonitrile-based one-dimensional porous carbon anode material. Polyimide based one-dimensional porous carbon anode materials have high specific surface area, better micropore structure and better electrochemical performance, which is mainly similar to the unique micropore structure of polyimide-based porous carbon fiber. Large specific surface area related. Doping nitrogen and other heterogeneous elements in carbon materials can regulate the properties of carbon materials and improve the electrochemical properties of carbon materials. Melamine, a nitrogen-rich substance, is added into polyacrylonitrile and electrospun. One dimensional nitrogen-doped porous carbon anode material for lithium-ion batteries with self-supporting structure was prepared by carbonation and activation for the first time. At the same time, the effects of different nitrogen content and activated pore making methods on the structure and electrochemical properties of one-dimensional nitrogen-doped porous carbon anode materials were studied. One-dimensional nitrogen-doped carbon anode materials obtained by ammonia treatment have good fiber morphology, high nitrogen content and good micropore structure. The self-supporting one-dimensional nitrogen-doped carbon anode has excellent electrochemical performance and its capacity is very high, reaching 1323mAh g ~ (-1). It is the highest capacity of carbon based anode material reported at present, and its cycling performance and rate performance are also very good. The reason is that this material has unique micropore structure and high nitrogen content. One-dimensional nanostructures are related to the presence of a higher amount of pyridine nitrogen than that reported in the present literature. Si has the highest theoretical capacity of 4200mAh g-1. However, due to the 400% volume variation of Si during charging and discharging, the cycling performance of Si-based anode materials is poor. In this paper, using nano-silica powder, polyvinyl alcohol and phenolic resin as raw materials, the method of electrospinning, solution impregnation and heat treatment is relatively simple. The self-supporting one-dimensional silicon-carbon composite anode materials for lithium ion batteries with certain preset space were obtained economically and safely. The simple and effective method of controlling the concentration of impregnated solution was adopted. The excellent electrochemical properties were obtained by adjusting the silicon, carbon content and microstructure of one-dimensional Si/C composite anode material.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM912

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