【作者】 赵松鹤；

【导师】 唐致远；

【作者基本信息】 天津大学 ， 应用化学， 2008， 硕士

【摘要】 本文分别采用高温固相法和溶胶-凝胶法合成锂离子电池负极材料钛酸锂,并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、TG-DTA对材料进行了表征。考察了固相法制备Li₄Ti₅O₁₂的工艺条件的影响,并对产物进行了循环伏安和交流阻抗的研究。实验结果表明:原料为锐钛矿TiO₂和Li₂CO₃、焙烧温度为900℃、保温时间为16h得到的材料性能最佳;交流阻抗测试表明Li₄Ti₅O₁₂表面并不形成钝化膜,将其用做锂离子电池负极材料,比碳负极材料更安全。对固相法制备的钛酸锂材料进行了Ag⁺、V⁵⁺、Sn⁴⁺、Mo⁶⁺、Ge⁴⁺、Nb⁵⁺等离子的掺杂。结果表明:Ag⁺的掺杂比为0.2时,0.2C下循环20次后电池比容量还保持在140.89mAh/g;掺杂Sn⁴⁺的量为0.1时,0.1C下循环20次后容量还保持在157.10mAh/g;掺杂Mo6+含量为0.2的材料20次循环后比容量保持在145.86 mAh/g;Ge⁴⁺离子掺杂比为0.1时,实验电池表现出了较高的首次放电比容量为174.38mAh/g,接近理论比容量。0.1C循环20次后的比容量还保持156.86mAh/g。采用溶胶-凝胶法合成了Li₄Ti₅O₁₂材料,考察了不同的操作方法、烧结时间对实验的影响,得到了较为理想的工艺流程。900℃热处理20h后得到的未掺杂钛酸锂,比容量一直保持在120mAh/g左右,有较高的充放电效率。并采用溶胶-凝胶法进行了Mo⁶⁺、Nb⁵⁺、Ge⁴⁺的有效掺杂,掺Mo⁶⁺量为0.5材料的大电流放电性能优于未掺杂的,其循环性能也有所改善。更多还原

【Abstract】 Lithium Titanate was synthesized by solid-state reaction and sol-gel method, respectively. The materials were investigated by constant current charge-discharge test, AC impedance, Cycle Voltammagram （CV） and characterized by X-ray Diffraction （XRD）, Scan electron microscope （SEM）, Thermogravimetry-differential thermoanalysis （TG-DTA）.The infection of the synthesis conditions of Li₄Ti₅O₁₂ prepared by solid-state reaction were investigated, CV and AC impedance were used to evaluate the product. The results demonstrated that the materials of best performance were prepared with Li2CO3 and anatase TiO2 as starting materials sintered at 900℃for 16h. There is not passivation film on the surface of Li₄Ti₅O₁₂ indicated that Li₄Ti₅O₁₂ was safer than carbon as Li-ion battery negative material.Solid-state reaction was used to gain ion-doped Li₄Ti₅O₁₂. The results showed that the ions of Ag⁺、V⁵⁺、Sn⁴⁺、Mo⁶⁺、Ge⁴⁺、Nb⁵⁺ were doped availably. The materials doped by Ag⁺、Sn⁴⁺、Mo⁶⁺、Ge⁴⁺ got best performance with different doping content: 0.2 Ag⁺ with 140.89mAh/g discharge capacity after 20cycles at 0.2C, 0.1 Sn⁴⁺ with 157.10mAh/g discharge capacity after 20cycles at 0.1C, 0.2 Mo⁶⁺ with 145.86 mAh/g discharge capacity after 20cycles at 0.2C, 0.1 Ge4+ with174.38mAh/g first discharge capacity 156.86mAh/g discharge capacity after 20 cycles at 0.1C.Li₄Ti₅O₁₂ was synthesized by sol-gel method, different operation ans sintered time were investigated to get the ideal experimental flow. The results showed that the materials sintered at 900℃for 20h got the capacity of 120mAh/g and better high charge-discharge efficiency. Mo⁶⁺、Nb⁵⁺、Ge⁴⁺ could also be doped by sol-gel method, the material doped with 0.5 Mo⁶⁺ was better than other doped. The cyclic stability of doped Li₄Ti₅O₁₂ was improved than pure Li₄Ti₅O₁₂.更多还原