【作者】 胡晨；

【导师】 刘韩星；

【作者基本信息】 武汉理工大学 ， 材料物理与化学， 2007， 博士

【摘要】 全固态薄膜锂微电池的研究引起人们越来越广泛的兴趣。到目前为止对正极薄膜的研究成果较多,而对于负极薄膜性能的研究开展的仍然十分欠缺。因而,研制高性能、低成本的负极薄膜对开发全固态薄膜锂微电池具有非常重要的意义。目前锂离子电池广泛采用的石墨类碳负极材料不可逆容量损失较大,而且存在安全性问题。Li₄Ti₅O₁₂作为锂离子电池负极材料时不存在上述问题,并且在充放电时结构几乎不发生变化,被称为“零应变”材料,具有非常优越的循环性能,因而引起科研工作者的广泛关注。为了获得高比容量和长循环寿命的负极薄膜,本文采用磁控溅射技术和旋涂法来制备Li₄Ti₅O₁₂薄膜;采用柠檬酸辅助溶胶-凝胶燃烧法合成了Li₄Ti₅O₁₂粉末,为磁控溅射镀膜提供靶材。因此,本文的主要研究工作为:系统研究了热处理温度、热处理时间等因素对柠檬酸辅助溶胶—凝胶法合成的Li₄Ti₅O₁₂粉末的结构及电化学性能的影响。采用柠檬酸为络合剂和燃烧剂,用溶胶-凝胶法燃烧法制备出了单相尖晶石Li₄Ti₅O₁₂。柠檬酸可以同时络合Ti（Ⅳ）和Li⁺,使反应物各元素在原子水平上混合均匀,从而降低离子在晶格重组时迁移的距离和迁移所必须的活化能,有利于降低反应温度。在750℃烧结6h的产物分散性好,平均粒度在100nm左右,产物的电化学性能优良。采用RF磁控溅射技术沉积制备了Li₄Ti₅O₁₂薄膜。利用X-射线衍射分析（XRD）、扫描电子显微镜（SEM）、原子力显微镜（AFM）和电化学性能测试等多种方法对Li₄Ti₅O₁₂薄膜进行了分析和表征。系统地研究了各个沉积参数对Li₄Ti₅O₁₂薄膜性能的影响,其中主要有射频功率、气体分压比、基底温度等对Li₄Ti₅O₁₂薄膜的结构形貌和电化学性能的影响。采用旋涂法制备了Li₄Ti₅O₁₂薄膜。结合差热—热重分析（TG/DSC）,XRD,SEM,AFM等测试和电化学性能测试等手段,系统地研究了原料配比、退火温度和时间、干燥温度等工艺参数对Li₄Ti₅O₁₂薄膜的结构、形貌及电化学性能的影响。使用交流阻抗法研究了锂离子在Li₄Ti₅O₁₂薄膜中的扩散过程。测定了锂离子在Li₄Ti₅O₁₂中脱嵌的OCV曲线及微分容量曲线,运用交流阻抗技术（EIS）测定了Li₄Ti₅O₁₂负极材料中锂离子的固相扩散系数。并对尖晶石型Li₄Ti₅O₁₂材料中锂离子的扩散系数随锂离子在材料中嵌入组成的变化规律进行了探讨。更多还原

【Abstract】 All-solid-state thin-film lithium micromatteries are of considerable current researchinterest. In recent years, considerable attention has been devoted to the investigation of the cathode film. By contrast, there have been few reports on the fabrication thin-film anode materials for lithium-ion batteries. Therefore, to develop high performance, low-cost anode thin film has a very important significance on the development of all- solid-state lithium microbatteries. The anode materials are usually carbon in commercial lithium ion batteries. However, the main drawback for carbonaceous materials is the passivation film formed during the first charging, which consumes lithium from the cathode. And there is still some safty concern. Li₄Ti₅O₁₂ is a promising anode material for lithium-ion batteries. During the process of Li⁺ intercalation and de-intercalation, its crystal form does not change and the total volume change is less than 1%, so it is regarded as a "zero strain" material. The lithium ion battery using Li₄Ti₅O₁₂ material as anode material has excellent reversibility, and the safety and reliability of the material is improved compared with that of carbon electrodes, such as graphite. Therefore, spinel Li₄Ti₅O₁₂ anode material has attracted substantial research interests of many scientists.In order to obtain high specific capacity and improve cyclibility of anode thin film, Li₄Ti₅O₁₂ thin film was prepared by spin coating and RF magnetron sputtering methods. As for target materials for RF magnetron sputtering, Li₄Ti₅O₁₂ powder was synthesized by critic acid-assisted sol-gel combustion method. Herein, the main research works are as follows:Li₄Ti₅O₁₂ powders with narrow size distribution and superior dispersion was successfully synthesized by a sol-gel combustion method using citric acid as a chelating agent and an organic fuel.The influence of annealing temperature, annealing time and the ratio of critic acid to metal ions on the structural and electrochemical properties of Li₄Ti₅O₁₂ powder was investigated. Citric acid can complex with Ti and Li at the same time to realize more uniform distribution of ions in molecular level. This decreased the ions rearrangement energy and distance. The sample synthesized at 750℃for 6h with average particle size of 100nm showed the best cycling behavior.Thin film of spinel Li₄Ti₅O₁₂ was successfully prepared by RF magnetron sputtering technology on Si/SiO₂/ Pt substrate. The characteristics of Li₄Ti₅O₁₂ thin films prepared by RF magnetron sputtering were examined by XRD, SEM, AFM, CV and galvanostatic charge/discharge cycling test. The influence of deposition condition, such as sputtering powers, O₂ to Ar gas ratio and substrate temperature, on the characteristic ofLi₄Ti₅O₁₂ thin films have been studied firstly.Thin film of spinel Li₄Ti₅O₁₂ was successfully prepared by a spin-coating technology used sol-gel method. We studied the effect of the preparation condition such as the initial Li /Ti molar ratios, the drying temperature, the annealing temperature and time on the films by means of TG/DSC, XRD, SEM, AFM and galvanostatic charge/discharge cycling test. Using these tests, we can observe the structure, morphology and electrochemical performance of the Li₄Ti₅O₁₂ thin film.The kinetics behaviors related to Li deintercalation/ intercalation process of spinel Li₄Ti₅O₁₂ were studied by means of electrochemical im spectroscopy （EIS） measurements. The open circuit voltage and the differential capacitance plot for Li₄Ti₅O₁₂ with the change of intercalation compositions have been measured. The lithium ion diffusion coefficients have been obtained by EIS method and the results indicate that its values are change with the change of lithium ion intercalation compositions.更多还原