【作者】 王云；

【导师】 顾大明；

【作者基本信息】 哈尔滨工业大学 ， 无机化学， 2010， 硕士

【摘要】 本研究采用溶胶凝胶法和高温固相法两种方法制备了Li₄Ti₅O₁₂负极材料,通过TG-DTA测试确定材料的烧结温度,XRD测试确定产物的物理组成和晶体结构,通过SEM研究颗粒的表面形貌和颗粒尺寸范围,用恒流充放电、循环伏安、交流阻抗测试方式来研究材料的电化学性能。采用溶胶凝胶法,以钛酸四丁酯和Li₂CO₃为原料、柠檬酸为络合剂,将前驱体在650℃烧结8h冷却研磨后再在850℃烧结16h制备了Li₄Ti₅O₁₂负极材料。通过对柠檬酸与Ti（Ⅳ）的摩尔比R的研究,发现当R = 1∶2时得到产物的性能最好,首次放电容量为148.65mAh/g,100次循环后保持在116.82mAh/g,容量保持率为78.59%。用LiAc代替Li₂CO₃作为锂源时,制得的Li₄Ti₅O₁₂负极材料颗粒致密性更好,电化学性能也更好,首次放电比容量为153.61mAh/g,100个循环之后放电比容量为124.37mAh/g,容量保持率为80.96%。采用高温固相法,以无定形TiO2和Li₂CO₃为原料制备了Li₄Ti₅O₁₂负极材料。通过研究各种条件对产物性能的影响,得到最优工艺条件:采用两步煅烧法,在650℃烧结8h再在850℃烧结16h后得到产物的性能最好,首次放电容量为159.16mAh/g,放电平台较长,100次循环后保持在143mAh/g左右,容量保持率约89.9%。尝试用葡萄糖对Li₄Ti₅O₁₂进行碳包覆,在预烧后加入葡萄糖混合充分,包覆质量百分比为20%产物的性能最好,首次放电比容量为172.94mAh/g,100次循环后放电比容量为135.93mAh/g,葡萄糖含量为10%的产物性能有一定的改进,30%的样品电化学性能反而下降。更多还原

【Abstract】 In this paper, Lithium Titannate was synthesized by sol-gel method and solid-state reaction respectively. In addition, Thermogravimetry-Differential Thermoanalysia（TG-DTA） was used to fix the sinter temperature, X-Ray Diffraction（XRD） to analyze micro-structure, Scanning Electron Microscope（SEM） to observe superficial morphology. Galvanostatic charge-discharge test, Cycle Voltammagram（CV） and Electrochemical Impedanc Spectroscopy（EIS） were used to study specific capacity and cyclic behavior.Anode material Li₄Ti₅O₁₂ for lithium ion batteries had been prepared by a sol-gel method with Tetra-n-butyl Titanate and Li₂CO₃ as starting materials and citric acid as a chelating agent. Citric acid can complex with Ti and Li at the same time to realize more uniform distribution of ions and smaller particle size in the solution. The effect of amount of chelating agent on electochemical properties of product was investigated. In our study, the sample synthesized at 650℃for 8h and 850℃for 16h with citric acid to titanium molar ratio R = 1∶2 showed the best discharge capacity of 148.65mAh/g and 116.82mAh/g for the first cycle and the 100th cycle respectively. The capacity retention was 78.59%。Anode material Li₄Ti₅O₁₂ using LiAc as Li source had smaller paricle distance and contacted each other closer. The material had better electochemical properties than the former using Li₂CO₃. It had a first discharge capacity of 153.61mAh/g and obtained 143mAh/g with a capacity retention of 80.96% after 100 cycles.Li₄Ti₅O₁₂ materials synthesized by solid-state reaction were prepared with amorphism TiO2 and Li₂CO₃ as the raw materials. The results demonstrated that the materials of best performance were sintered by two-step method, the raw materials were pre-sintered at 650℃for 8h then were treated at 850℃for 16h. The Li₄Ti₅O₁₂ as the anode materials for lithium ion battery had a first discharge capacity of 159.16mAh/g, and a long platform around the voltage of 1.55V. The sample obtained a capacity of 143mAh/g with a capacity retention of 89.9% after 100 cycles. The materials showed fine cycling properties.The carbon modification using dextrose as carbon source was researched. The results showed that 20%wt was the best carbon doping quantity, the materials had a first discharge of 172.94 mAh·g-1. The sample with 10%wt carbon had a little improvement in cyclic stability and diacharge capacity. However, the 30%wt carbon doped sample’s electrochemical properties were weakened.更多还原