【作者】 甘小燕；

【导师】 刘韩星；

【作者基本信息】 武汉理工大学 ， 材料学， 2006， 硕士

【摘要】 锂微电池可广泛应用于智能卡、CMOS基集成电路和微设备等领域,是近几年电池研究的主要方向之一。近年来,尽管一些全固态薄膜锂微电池逐渐面世,但它们的性能仍需进一步改善,特别是对于正极薄膜性能的改善和制造工艺的优化。因此,研制高性能、低成本的正极薄膜对开发全固态薄膜锂微电池具有非常重要的意义。 本文选择引人注目的锂电池正极材料LiMn₂O₄作为研究对象,采用旋涂技术的溶液沉积法成功制备了尖晶石结构的锂微电池LiMn₂O₄正极膜。考察了采用该法在制备LiMn₂O₄薄膜过程中前驱体溶液中溶剂、溶液浓度、匀胶速度和时间等对薄膜质量的影响。同时还结合TG/DSC,XRD,（FE）SEM,AFM,ICP,CV测试和电化学性能测试等手段,并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LiMn₂O₄薄膜的结构、形貌及电化学性能的影响。对这些工艺参数的优化结果表明:原始Li:Mn配比为1.05:2.00,干燥温度为280℃,在280℃退火30min获得的LiMn₂O₄薄膜具有最佳的综合性能。该条件下制得的薄膜表面均一、致密、无裂痕,在3.0～4.3V以50μA/cm²的电流充放电时,首次放电容量为37.3μAh/（cm²·μm）,经50次循环后的每次容量损失仅为0.011%。 在此基础上,本文还研究了Al³⁺离子掺杂对LiMn₂O₄薄膜结构及电化学性能的影响。研究表明:少量的Al掺杂并没有改变LiMn₂O₄的尖晶石结构,且随着Al³⁺的掺杂量的增多,晶格产生收缩,尖晶石结构的稳定性增强。掺Al之后的LiAl_0.Mn_1.9O₄与没有掺杂的LiMn₂O₄相比,相变程度得到了抑制。充放电结果表明,Al的掺入会降低LiMn₂O₄正极膜的放电容量,但能在一定程度上提高锂锰氧薄膜的循环性能。LiAl_0.05Mn_1.95O₄正极膜不但具有较高的初始放电容量,循环性能也较理想,是一个比较理想的掺杂比例。更多还原

【Abstract】 Lithium micro-battery has wide applications, such as smart cards, COMS-based integrated circuits and micro-devices, and as a result, has become one of the most studied branches of batteries in recent yeas. Many all-solid-state lithium micro-batteries have been reported previously. However, the properties of these batteries still need improving, especially for the improvement of the electrochemical performances of cathode films and the optimization of fabrication techniques of thin films. Accordingly, the fabrication of high-performance and low-cost cathode thin films plays an important role to develop all-solid-state lithium micro-batteries.In this thesis, the remarkable cathode LiMn₂O₄ was chosen as a major subjects investigated. Thin film electrode of spinel LiMn₂O₄ for rechargeable lithium micro-batteries was successfully prepared by a solution deposition route. The Li-Mn-0 solution was deposited on electronically conductive Au substrate by a spin coater. The effects of solvent, concentration of the solution and the rotation speed and time during spin-coating on the quality of the films were explored. At the same time, the film performance has been studied as a function of preparation condition, i.e. the initial Li/Mn molar ration, the drying temperature, the annealing temperature and time. The thermal decomposition behavior of the precursor powder was examined by TG/DSC to determine the temperature of heat-treatment. XRD, SEM and AFM were used to characterize the structures, phase composition, morphology of the thin films. The electrochemical properties of the thin films were also investigated using cyclic voltammeter （CV） and galvanostatic charge/discharge cycling. The thin films obtained from the optimal fabrication condition （Li/Mn= 1.05:2, dried at 280℃, annealed at 800℃ for 30min） were homogeneous, dense, crack-free, and showed good intercalation kinetics and very promising cycling behavior. The first discharge capacity is37.3 μAh/（cm²·μn）, and the capacity loss per cycle is about 0.011 % after 50 cycles at current density of 50μA/cm² between 3.0-4.3V.The influences of Al³⁺ doping on structure and electrochemical properties of LiMn₂O₄ thin films were also studied in this thesis. It is found that Al-doped lithium manganeseoxides keep the same structure as spinel LiMri2O4 The lattice parameters of the samples decreased with increasing amount of doping aluminum, which helps to stabilize the spinel structure. Compared with the un-doped LiMn2O4, the two-phase change of Al-doped LiAlo iMni 9O4 thin film was suppressed. The electrochemical performance tests showed the first discharge capacities decreased with the increase of doping Al, however, the cycleability was improved. According to both the capacity and the cyclic property, LiAloosMnigsC^ thin film had favorable electrochemical performance.更多还原