【作者】 李丽；

【导师】 吁霁；

【作者基本信息】 南昌大学 ， 化学， 2017， 硕士

【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SnO₂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SnO₂为研究中心,从改变形貌以及与碳材料复合两个方面对SnO₂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SnO₂纳米粒子并控制反应时间合成了一系列SnO₂@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,SnO₂@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/SnCl₂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/SnO₂纳米纤维,然经热处理得到SnO₂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SnO₂/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,SnO₂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,SnO₂/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,SnO₂（2%）/rGO复合材料仍可维持649 mAh g-1,且库伦效率接近100%。更多还原

【Abstract】 lithium ion batteries have been paid much attention by researchers at home and abroad because of their excellent electrochemical performance.and It is also the most potential energy storage device for new energy vehicles.As one of part of lithium ion battery.the lithium storage performance of anode material has a direct impact on the performance of the whole battery,so it has been the focus of attention of researchers and producers.metal oxide SnO₂ with high specific capacity,low toxicity and low cost has become the most potential substitute material for graphite materials.However,it also has some inevitable disadvantages,researchers at home and abroad have launched a series of works around its shortcomings.In this paper,taking SnO₂ as the research center.SnO₂ modification study was carried out by the two aspects of changing the morphology and combineing with carbon materials to improve the electrochemical performance.details are as follows.Taking carbon nanotubes with initial treatment as as containers,solution containing Sn2+ was filled into the empty channels of carbon nanotubes due to surface tension and capillary action,the SnO₂ nanoparticles were grew as a result of in situ oxidation reduction reaction and a series of SnO₂@OCNTs（8 h-100 h）composites were synthesized by controlling the reaction time.The physical and chemical tests of TG and TEM showed that the number of particles in carbon nanotubes was increased with the increase of filling time.the results is in agreement with the electrochemical test results.when the reaction time was 100 h,SnO₂@OCNTs（100 h）showed the best lithium storage performanc in terms of an high initial capacity of 2200 mAh g-1 at the current density of 78 mA g-1,excellent rate performance（804 mAh g-1 at 0.4 A g-1after 50 cycles）and long cycle life（674 mAh g-1 at 4 A g-1after 200cycles）.Using PVP/SnCl₂ solution as precursor,The PVP/SnO₂ nanofibers with different diameters were prepared by electrospinning technique of controlling the spinning parameters such as voltage and concentration.and SnO₂ nanofibers were obtained by heat treatment.than physically mixing it with graphene oxide GO,three kinds of SnO₂/rGO composites with different diameters were prepared by heat treatment and ultrasonic treatment.a series of phase characterization and electrochemical characterization were carried out.The electrochemical results show that the smaller the diameter of the SnO₂ nanofibers,the better electrochemical performance of the composite.the SnO₂（2%）/rGO composites release a super high discharge capacity（1987 mAh g-1 at 0.4 A g-1 after 50s）and long cycle life（649 mAh g-1 at 4 A g-1after 1000 cycles with 99.9% coulombic efficiency）.更多还原