二氧化锡—碳基复合材料的制备及电化学储锂性能的研究

发布时间：2018-06-10 02:15

本文选题：锂离子电池 + 负极材料　；参考：《南昌大学》2017年硕士论文

【摘要】：锂离子电池因其优异的电化学性能一直受到国内外研究人员的关注,也是新能源汽车最有潜力的储能装置。而作为锂离子电池一部分的负极材料,其储锂性能的好坏直接影响到整个电池性能的高低,因而其一直是各国研究人员和电芯生产商关注的焦点。金属氧化物SnO_2因具有较高的比容量、较低的毒性以及低成本等优点成为石墨基负极材料最有潜力的替代材料。然而本身亦存在一些不可避免的缺点。围绕其缺点,国内外研究人员展开了一系列的工作。本文以SnO_2为研究中心,从改变形貌以及与碳材料复合两个方面对SnO_2进行改性研究以提高它的电化学性能,具体内容如下:1、以预先处理后的碳纳米管为容器,通过调控表面张力,利用毛细管作用将含有锡离子的溶液引入碳纳米管空腔,经过原位氧化还原反应生成SnO_2纳米粒子并控制反应时间合成了一系列SnO_2@OCNTs(8 h-100 h)复合材料。经XRD、TG、TEM等理化测试表明,随着填充时间的增加,进入管内的粒子就越多,此结果也与电化学测试结果相一致。当反应时间为100 h,SnO_2@OCNTs(100 h)表现优异的储锂性能。在78 mA g-1电流密度下,首次放电比容量可达2250 mAh g-1,在0.4 A g-1下循环50次,其比容量值为804 mAh g-1,甚至在较大电流密度4 A g-1下循环200圈,材料依然保持了674 mAh g-1的放电比容量。2、以PVP/SnCl_2溶液为前驱体,采用静电纺丝技术,通过控制电压、浓度等纺丝参数制备了不同直径大小的PVP/SnO_2纳米纤维,然经热处理得到SnO_2纳米纤维。再将其与氧化石墨烯GO进行物理混合,经后续的热处理和超声处理制备了三种不同直径大小的SnO_2/rGO的复合材料,并对其进行一系列的物相和电化学表征。电化学测试结果表明,SnO_2纳米纤维直径越小,与r GO复合后,复合材料的电化学性能越优异。其在0.4 A g-1的电流密度下进行充放电,SnO_2/rGO循环50圈后,其比容量值可维持1987 mAh g-1。甚至在4 A g-1极大的电流密度下循环1000圈,SnO_2(2%)/rGO复合材料仍可维持649 mAh g-1,且库伦效率接近100%。
[Abstract]:Lithium ion batteries have been paid attention by researchers at home and abroad because of their excellent electrochemical performance, and they are also the most potential energy storage devices for new energy vehicles. As a part of lithium ion battery anode material, its lithium storage performance directly affects the performance of the entire battery, so it has been the focus of attention of researchers and core manufacturers all over the world. Sno _ 2 has become the most potential substitute for graphite-based anode materials because of its high specific capacity, low toxicity and low cost. However, there are some inevitable shortcomings. Around its shortcomings, researchers at home and abroad began a series of work. In this paper, Sno _ 2 was modified to improve the electrochemical performance of SnO _ 2 by changing its morphology and compounding with carbon materials. The specific contents are as follows: 1, using pre-treated carbon nanotubes as container, and regulating surface tension. A series of SnO2 nanocomposites were synthesized by in-situ redox reaction to SnO2 nanoparticles and a series of SnO2 / OCNTsm 8h-100hs composite materials were synthesized by capillary reaction to introduce tin ions into carbon nanotubes (CNTs) cavities. The physicochemical tests such as XRDX TGX TEM show that the more particles enter the tube with the increase of filling time, the more particles enter the tube, and the results are in agreement with the electrochemical results. When the reaction time is 100 h, SnO _ 2C _ (2) C _ (CNTsN) (100 h) exhibits excellent lithium storage performance. At the current density of 78 Ma g ~ (-1), the specific capacity of the first discharge can reach 2250 mAh g ~ (-1), and the specific capacity is 804 mAh g ~ (-1) for 50 cycles at 0.4 mg ~ (-1), even when the current density is high (4 A g ~ (-1). The specific discharge capacity of 674 mAh g-1 was maintained. Using PVP / SnCl2 solution as precursor, PVP / SnCl _ 2 nanofibers with different diameters were prepared by using electrospinning technology and controlling the spinning parameters such as voltage and concentration. However, SnO _ 2 nanofibers were obtained by heat treatment. Three kinds of SnO _ 2 / rGO composites with different diameters were prepared by subsequent heat treatment and ultrasonic treatment, and a series of phase and electrochemical characterization were carried out. The results of electrochemical measurement show that the smaller the diameter of SnO-2 nanofibers, the better the electrochemical properties of the composites after composite with r go. After charging and discharging SnOs at the current density of 0.4 Ag ~ (-1) for 50 cycles, the specific capacity can be maintained at 1987 mAh g ~ (-1). Even at a maximum current density of 4Ag ~ (-1), the Sno _ 2C _ (2) / R _ (go) composite can still maintain 649 mAh g ~ (-1), and the Coulomb efficiency is close to 100 cycles.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33;TM912

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