【作者】 赵亚飞；

【导师】 刘世斌；

【作者基本信息】 太原理工大学 ， 化学工艺， 2012， 硕士

【摘要】 Li4Ti5O12是一种理想的锂离子电池负极材料,充放电的过程中材料的晶体结构几乎不发生变化,Li+的嵌入和脱嵌对材料的晶体结构几乎没有影响,也就是所谓的“零应变”材料；嵌锂电位较高(1.55V vs.Li+/Li),充放电过程中不会引起金属锂的析出,能够在大多数有机电解液中使用；理论放电比容量为175mAh/g,实际放电比容量可高达150-160mAh/g；锂离子扩散系数比碳材料高一个数量级；库伦效率高、原材料来源广、清洁环保。钛酸锂具备了下一代锂离子电池所必需的充放电次数多、充放电过程快、安全性好的特性。本文采用高温固相法合成锂离子电池负极材料钛酸锂,采用室温恒流充放电、交流阻抗、循环伏安等测试方法,以及XRD.SEM对材料进行了表征。重点考察了Y掺杂、Y和碳协同掺杂、以及不同掺杂量和不同碳源对Li(4-x/3)YxTi(5-2x/3)012(x=0.1)形貌、粒径和电化学性能的影响。结果表明,使用蔗糖为碳源合成的复合材料Li(4-x/3)YxTi(5-2x/3)012/C(x=0.1)表现了相对较好的倍率性能和循环稳定性,在0.15C.0.4C.0.7C.1.4C和3.3C倍率下材料首次放电比容量分别为149.0、144.5、144.5、141.3和118.0mAh/g,3.3C倍率下循环10次后容量仍保持为115.0mAh/g,明显优于纯Li4Ti5012。电化学交流阻抗表明,使用蔗糖为碳源合成的Li(4-x/3)YxTi(5-2x/3)012/C复合材料的阻抗从纯Li4Ti5012的912.5Ω降低到227.7Ω。更多还原

【Abstract】 Spinel Li4Ti5O12is a promising lithium ion battery anode material. It has some evident advantages:there is negligible volume change during charge/discharge process （the so-called "zero-strain insertion material"）, so it possesses excellent reversibility; its Li-insertion potential is at about1.55V vs. Li+/Li, which is high than the reduction voltage of common electrolyte; the diffusion coefficient is2×10-11cm2/s, so it has excellent lithium ion mobility that promising for high-rate battery applications. Furthermore, this material accommodates Li+with theoretical capacity of175mAh/g. Compared with graphite anode material, Li4Ti5O12is considered to be of better rate performance and safety.In this text, Materials for lithium ion batteries was synthesized through a simple solid state reaction in an inert atmosphere using yttria as Y3+dopant source and sucrose or conductive carbon black as carbon source. Composites were characterized by XRD, SEM analysis combined with electrochemical tests, and the effects of Y3+doping, Y3+and carbon doped simultaneously, and different carbon sources such as sucrose or conductive carbon black on the morphology, particle size, electrochemical and performance of anode materials were investigated. It shows that Li（4-x/3）YxTi（5₂x/3）O12（x=0.1） composites using yttria as Y3+dopant source and sucrose as carbon source exhibited a relatively good rate capability and cycling stability. At the charge-discharge rate of0.15C,0.4C,0.7C,1.4C and3.3C, its discharge capacities were149.0,144.5,144.5,141.3and118mAh/g, respectively. After10cycles at3.3C, its discharge capacity remained at115.0mAh/g. The impedance Rct of this material is227.7Ω, while that of the undoped Li4Ti5O12material is912.5Ω.更多还原