【作者】 唐敏；

【导师】 何建平；

【作者基本信息】 南京航空航天大学 ， 材料学， 2006， 硕士

【摘要】 锂离子二次电池是20世纪90年代发展起来的新型二次电池,因其优异的性能,发展十分迅速,已广泛用于国民经济建设与生活的各个方面。作为一种新型能源,目前锂离子电池仍存在价格较高、安全性不足等问题。而钠离子电池因具有成本低、安全性能高等独特的优势,是一很有潜力的替代品。钠离子电池的优异性能在很大程度上取决于正、负极材料的选择和制备,在当前负极材料的研究取得良好进展的前提下,获得钠离子嵌入/脱嵌性能良好的正极材料成为该类电池发展的一个关键。本文将借助X-射线衍射、扫描电镜、透射电镜、差热分析以及电化学测试等方法,系统研究多种制备法对所合成的钠离子二次电池正极活性材料氟磷酸亚铁钠的微结构以及循环可逆容量、循环伏安性能、交流阻抗谱的影响。首先采用固相法制备了氟磷酸亚铁钠粉体,研究了不同煅烧温度对合成材料显微结构和电化学性能的影响,结果表明750℃下合成材料体现出较好的电化学性能,首次放电容量为60mAh/g,循环20次后,容量下降为51.1mAh/g。随后采用在材料表面覆碳的方法对氟磷酸亚铁钠进行改性,结果表明当掺碳量为5%时,电池的首次放电比容量为111mAh/g,第20次的放电比容量为102.1mAh/g。比较了固相法和溶胶凝胶法合成的氟磷酸亚铁钠粉体的电化学性能,结果表明溶胶凝胶法合成的正极电化学性能明显优于固相法合成的正极电化学性能:首次放电比容量达到了91mAh/g,20次循环后放电比容量为81.71mAh/g。本文还探索了利用溶胶凝胶法在模板中合成氟磷酸亚铁钠纳米线,发现该法制备的材料初次放电容量高达119mAh/g,循环20次后的放电比容量为110mAh/g。更多还原

【Abstract】 Lithium-ion battery is a new type of secondary batteries developed during 1990’s. Rapid progresses have been made in the research on lithium ion batteries due to its superior properties for recent years. As a new energy sources, lithium ion battery has the problem of high price and security trouble, while sodium ion battery prevails over it due to its low cost and excellent security performance, so sodium ion battery will be an attractive potential substitution for lithium ion battery. As we know the excellent performance of sodium ion battery depends deeply on the different type and preparation of anode/cathode material. While the effective research on anode material has already been done, study of cathode material with good electrochemical performance has become a key factor. In this thesis, The physical properties of a series of Na2FePO4F cathode materials synthesized by various routes are instigated and discussed in the light of structural (XRD), thermal (DTA) analyses and particle size distribution. Their microstructures were studied by transmission electron microscope (TEM) and scan electron microscope (SEM). The electrochemistry property were evaluated with cells containing the synthesized Na2FePO4F as positive electrode.The Na2FePO4F cathode materials for sodium ion battery were prepared by solid state reaction and the influence of synthesizing temperature and morphology on the electrochemical performance of Na2FePO4F powders in sodium ion batteries were systematically studied. The results indicate that Na2FePO4F synthesized at 750℃exhibited good electrochemical performance, whose first specific discharge capacity is 60mAh/g, after 20 times cycling, the average specific discharge capacity is 51.1mAh/g. Then we prepared Na2FePO4F cathode material coated with carbon by solid-state reaction. As cathode material, the first discharge capacity is 111mAh/g and the capacity reduces to 102.1mAh/g after 20 cycles. Ultrafine Na2FePO4F powders synthesized by a sol-gel process also shows a good electrochemical performance. Obviously, it is better than the material prepared by solid-state process: the first discharge capacity is 91mAh/g, after 20 cycles the specific capacity is around 81.71mAh/g. Besides, we tried to prepare arrays of nanowires using AAO更多还原