Preparation And Performance Of The Novel Materials For Power Lithium Ion Batteries

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.