【作者】 靳永利；

【导师】 李娟；

【作者基本信息】 新疆大学 ， 物理化学， 2007， 硕士

【摘要】 由于锂离子电池采用锂离子存贮材料取代金属锂,改善了锂电池由于枝晶生成所造成的安全隐患及循环性能差的缺点,并保留了锂电池高电压的优点,同时还兼具能量密度大,重量轻,体积小,循环寿命长,无记忆效应,环境友好等优点,近来发展较快。本论文就锂离子电池负极材料锡氧化物和尖晶石Li4Ti5O12及其与碳纳米管的复合电极材料进行了研究。主要工作分为以下两部分:(一)本部分采用水热法制备了纯相SnO和SnO2纳米负极材料,采用水热法制备了不同摩尔比的SnO/MWCNTs和SnO2/MWCNTs纳米负极材料。运用X射线衍射(XRD)、红外光谱(FTIR)和透射电镜(TEM)及电化学性能测试对合成材料进行表征和电化学性能研究。主要内容如下:1.纳米SnO和SnO2电极材料水热法合成、表征和电化学测试。X射线衍射谱图分析可知, SnO为Romarchite. Syn型,SnO2为锡石型。TEM测试表明产物为纳米结构。电化学测试表明水热法合成过程中加入PEG-400制备得到的SnO和SnO2负极材料的循环性较未加PEG-400制备得到的SnO和SnO2要好。2.水热法合成不同摩尔比的纳米SnO/MWCNTs复合电极材料。X射线衍射谱图表明水热法成功合成了纳米SnO/MWCNTs复合材料。TEM测试表明复合材料中的SnO为纳米棒,并均匀附着在MWCNTs表面,电化学测试表明碳纳米管的加入可以改善SnO的电化学性能。3.水热法合成不同摩尔比的纳米SnO2/MWCNTs复合电极材料。X射线衍射谱图表明水热法成功合成了纳米SnO2/MWCNTs复合电极材料。TEM测试表明复合材料中的SnO2为纳米粒子,大部分均匀附着在MWCNTs表面,少量进入MWCNTs管内,电化学测试表明复合材料的循环性能较好。(二)本部分采用微波法成功制备尖晶石Li4Ti5O12,并在此基础上研究对其进行多壁碳纳米管的复合改性。采用X射线衍射(XRD)、红外光谱(FTIR)和透射电镜(TEM)系统地研究了微波功率、辐射时间、锂源和反应物配比对合成Li4Ti5O12的影响,并采用电化学测试手段研究了微波法合成Li4Ti5O12的电化学性能。主要内容如下:1.在功率为500W和700W,时间为10min和15min,分别以LiOH·H2O和Li2CO3为锂源(锂源过量8%)探讨微波法合成纳米尖晶石Li4Ti5O12电极材料的条件。对样品进行XRD和FTIR测试分析,发现在700W,15min条件下可以合成较纯的尖晶石Li4Ti5O12,但由于锂源过量,合成样品中有少量Li2TiO3生成。TEM照片表明合成的样品为30nm左右的纳米粒子。对以Li2CO3为锂源在功率500W和700W,15min条件合成的样品进行电化学测试,合成的样品具有良好的循环性能。2.以LiOH·H2O和Li2CO3为锂源,微波法合成纯相尖晶石结构Li4Ti5O12电极材料。反应条件为功率700W,时间为15min。样品的XRD和FTIR测试分析表明,在此条件下可以合成纯相尖晶石Li4Ti5O12。TEM照片表明合成的样品为小于50nm左右的纳米粒子。分别对在此条件合成的样品在不同电流密度下进行电化学测试,结果表明合成的样品具有良好的循环性能。3.微波法合成不同摩尔比尖晶石结构Li4Ti5O12/MWCNTs复合电极材料。反应条件为在功率700W,时间15min,以Li2CO3为锂源。更多还原

【Abstract】 Instead of lithium metal, lithium-storage materials were adopted as negative electrode materials in lithium-ion batteries, the hidden insecurity and poor cyclic performance caused by the formation of lithium crystalline had been improved, and the high-voltage merit of lithium batteries was remained as well. At the same time, the lithium-ion batteries possessed other advantages such as high energy density, little weight, small volume, long cycle-life, little effect of memory and better environment benefits etc,so the lithium ion batteries had been developed rapidly during the past few years. This thesis concentrated on the tin-based oxide, spinel Li4Ti5O12, and their MWCNTs composite materials as anode material for lithium secondary batteries. The major work can be separated two parts.(一) In this section, the SnO and SnO2 nanophase anode materials were prepared by hydrothermal method, the different mole ratio of SnO/MWCNTs and SnO2/MWCNTs anode nanomaterials were prepared by hydrothermal method. The characteristic and electrochemical property of samples were investigated by powder X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and electrochemical tests. The major contents as followed:(1) The SnO and SnO2 anode nanomaterials were prepared by hydrothermal method. The results of XRD showed that the Romarchite. Syn SnO and cassiterite SnO2 were synthesized by hydrothermal method. TEM showed that the microstucture of the sample was nanophase. the results of electrochemical tests showed that the cycliability of SnO and SnO2 which were added PEG-400 in preparing process were better than not added PEG-400.(2) The different mole ratio of SnO/MWCNTs nanocomposites anode materials were prepared by hydrothermal method. The results of XRD showed that the SnO/MWCNTs nanomaterials were successfully prepared by hydrothermal method. TEM photos showed that the SnO microstucture of the nanocomposites was nanorod and homogeneously dispersed on the MWCNTs surface. the results of electrochemical tests showed that MWCNTs could improve the cycliability of SnO.(3) The different mole ratio of SnO2/MWCNTs nanocomposites anode materials were prepared by hydrothermal method. The results of XRD showed that the SnO2/MWCNTs nanomaterials were successfully prepared by hydrothermal method. TEM images showed that the SnO2 microstucture of the nanocomposites were nanoparticles, most of particles were homogeneously dispersed on the MWCNTs surface and a few particles were in the hollow of MWCNTs. The results of electrochemical tests showed that the samples had excellent cycliability.(二) In this section, spinel Li4Ti5O12 has been synthesized by microwave synthesis method. The factors of the microwave power, radiation time, lithium source and reactant ratio which can effect on the final materials were investigated by means of XRD, FTIR, TEM, and electrochemical performances of Li4Ti5O12 were studied by electrochemical techniques. The major contents as followed:(1) The synthesis conditions of spinel Li4Ti5O12 were discussed, the discussed conditions were lithium source which were LiOH·H2O and Li2CO3 (Li excess 8%), microwave power which were 500W and 700W, radiation time which were 10min and 15min. The results of XRD and FTIR showed that the spinel Li4Ti5O12 could be synthesized when microwave power was 700W and radiation time was 15min, but a small amount of Li2TiO3 was found that may be caused by Li excess 8%. TEM showed that the microstucture of the sample were nanoparticles which diameter was about 30nm. The electrochemical performance of samples which were synthesized Li2CO3 as lithium source at 500W and 700W for 15min, the results of tests the samples have excellent cycliability.(2) The nonophase spinel Li4Ti5O12 was synthesized by microwave method. The condition of synthesis was that LiOH·H2O and Li2CO3 as lithium source at 700W for 15min. The results of XRD and FTIR showed that the nonophase spinel Li4Ti5O12 could be synthesized at 700W for 15min. TEM showed that the microstucture of the samples were nanoparticles which diameter was less than 30nm. the results of electrochemical tests showed that the samples had excellent cycliability.(3) The different mole ratio of Li4Ti5O12/MWCNTs nanocomposites anode materials were synthesized by microwave method. The nanocomposites were synthesized when Li2CO3 as lithium source at 700W for 15min.更多还原