【作者】 刘建红；

【导师】 吴伯荣；

【作者基本信息】 北京理工大学 ， 环境工程， 2015， 博士

【摘要】 本论文采用多种材料制备方法包括液相共沉淀法、液相球磨法及固相烧结法制备了几种新型车用锂离子动力电池正、负极材料,主要涉及改性LiMn2O4材料、5V尖晶石LiNi0.5Mn1.5O4材料、富锂锰基材料Li1.128Ni0.305Mn0.563O2以及新型钛系负极SrLi2Ti6O14材料。研究了不同掺杂离子对LiNi0.5Mn1.5O4材料不同的改性机理,探讨了富锂锰基材料前驱物的成核过程机制,考察了改性尖晶石锰酸锂材料以及富Li锰基层状材料的电化学性能,研究它们的电化学动力学特征。另外,采用非原位XRD无标样定量分析技术研究了新型钛系负极SrLi2Ti6O14材料固相合成过程机理,总结出最优的烧结制度,并结合全电池工况测试结果证实其具有优异的动力学特征。此外,本文的研究工作还包含了上述材料在全电池中的电化学行为研究结果,这对于各材料的研究发展方向及潜在的应用均有一定的借鉴意义。主要工作内容可概括如下:采用Co/Ni复合掺杂LiMn2O4材料,研究复合掺杂后的材料在3-5V平台和3-4.3V两个不同电压区间的电化学性能差异,并结合阻抗谱技术阑述差异产生的机理原因。研究Al3+、Cu2+及Al3+/Cu2+对LiNi0.5Mn1.5O4材料不同的掺杂效果,对比各种掺杂方式的动力学性能,讨论了两种离子不同的掺杂机理,并结合电化学性能差异阑述Al/Cu复合掺杂所带来的协同效应。研究富锂材料Li1.128Ni0.305Mn0.563O2液相前驱体在空气气氛下合成过程,采用各类测试手段分析了不同时间段前驱物的物相组成、元素组成、颗粒大小及形貌,对前驱物的成核及生长机制展开研究。采用不同的烧结制度制得了一系列具有不同一次颗粒粒径的富锂锰基材料Li1.128Ni0.305Mn0.563O2。结合电化学性能测试、晶体结构精修及化学扩散系数的对比研究,讨论了一次颗粒粒径与电化学动力学参数之间的关系。采用自制的富Li锰基材料Li1.128Ni0.305Mn0.563O2为正极组装成容量为5Ah的全电池,在不同的充放电电压范围内研究其电化学性能行为差异。在4.2V电压范围内,与LiNixMnyCozO2及LiMn2O4全电池作全面的电性能对比,分析了循环前后富锂锰基材料的结构变化,简要讨论了富锂锰基全电池容量衰减机理,总结出富锂锰基全电池电性能特点,对于将来富Li锰基材料潜在的应用方向及领域提出参考建议。研究了新型钛系负极SrLi2Ti6O14的烧结过程,采用非原位XRD无标样定量分析方法分析各烧结温度下的烧结产物物相组成,分析杂相的生成及消除过程,并得到最佳的纯相合成温度。采用合成的纯相SrLi2Ti6O14材料为负极,组装成容量为6Ah的功率型全电池,并采用HPPC方法测试其实际的功率性能,同时与Li4Ti5O12作对比,从动力学因素上全面证明了SrLi2Ti6O14材料具有优异的功率性能,阐述了其在混合动力车上应用的巨大潜力。更多还原

【Abstract】 Several material preparation method, including liquid phase co-precipitation, liquid phase ball-mixing and solid phase sintering, were employed to prepare several cathode/anode material of power lithium ion batteries for electric vehicle. These materials involve modified spinel Li Mn2O4, Li Ni0.5Mn1.5O4, Li-rich layered material and one novel titanium-based anode Sr Li2Ti6O14. In this paper, modified mechanisms of different doped ions for Li Ni0.5Mn1.5O4, growth mechanisms of the precursor of Li-rich material,electrochemical performances and kinetic properties in electrochemical reaction of these materials were discussed. In addition, phase transition mechanism of titanium-based anode Sr Li2Ti6O14 in sinteringwas studied used standardless quantitative analysis of ex-situ X-ray diffraction. The optimal sintering condition of Sr Li2Ti6O14 was presented and potential application in high power batteries was discussed.In addition, some research findings gotten in full cell of above materials were also presented in this paper. The above studies’ results could provide significant reference for material study in lithium ion batteries field.Main results could be summarized as followings:Co/Ni co-doped Li Mn2O4 spinel material was prepared. Differences of electrochemical performances in different voltage ranges were studied. The potential reason was discussed based electrochemical impedance spectrum technology.Doped effect of Al3+, Cu2+ and Al3+/Cu2+ for Li Ni0.5Mn1.5O4 was studied. Kinetic properties of the Li Ni0.5Mn1.5O4 doped by different cation were tested and doped mechanisms of the doped ions were discussed. Combined with their electrochemical performances, the synergistic effect of Al3+/Cu2+ co-doping mode was elucidated.The liquid co-precipitation process of precursor of Li-rich layered material was studied. The phase, element distribution, particle size and morphology were characterized by different method. The cored mechanism and growth process of precursor were discussed.Li-rich layered materials with different primary particle size were prepared. The differences of their electrochemical performances, lattice structure and Li+diffusion capability were compared. The relationship between primary particle size and electrochemical kinetic properties was discussed.The full cells with ~5 Ah using self-produced Li-rich layered material Li1.130Ni0.304Mn0.565O2 as cathode were prepared. Difference of electrochemical performances in different voltage ranges was investigated. In 3-4.2V range, the difference electrochemical behaviors among Li1.130Ni0.304Mn0.565O2,Li Ni0.333Mn0.333Co0.333O2 and Li Mn2O4 were compared. The lattice changing before and after cycling of Li1.130Ni0.304Mn0.565O2 was characterized. The possible capacity decay mechanism of Li1.130Ni0.304Mn0.565O2 full cell was discussed, and electrochemical characterization of Li-rich material full cell was summarized. Some potential applied direction and field were presented.The sintering process of new titanium-based anode Sr Li2Ti6O14 was studied. The phase composition of materials in different sintering temperature was analyzed using standardless quantitative analysis method. Based on the analysis results of impurity generation and elimination, the best sintering condition was presented.Full cells with ~6 Ah were designed and prepared used the pure Sr Li2Ti6O14 and Li4Ti5O12 as anode, respectively. Their power performances of these full cells were compared based on HPPC testing results. The significant power performance of Sr Li2Ti6O14 had been verified.更多还原