Preparation Of The Lithium-ion Battery Cathode Materials For Lithium Nickel Cobalt Oxide And Modified

Layered structure LiNi_1-xCo_xO₂ positive materials and LiNio LiNi_0.7Co_0.3-xM_xO₂ (M=A1, Mn) materials of lithium ion secondary batteries were prepared by solid phase mixing reaction and liquid phase chemical methods in this paper. Their crystal structures and electrochemical performances were studied by using XRD, SEM, micro-electrode cyclic voltammetry, galvanostatic charge/discharge test and measurement and so on. The conclusions were showed as following:1. Compared the crystal structures and electrochemical properties of LiNi1_xCoxO2 positive materials which were synthesized by different methods, it could be discovered that the effect of solid solution, the degree of order of cations, charge-discharge capability and cyclic performances of LiNi1-xCoxO2 solid solution prepared by liquid phase chemical method were superior to those of LiNi1_xCoxO2 prepared by solid phase mixing reactio.2. The characters of LiNi1-xCoxO2 solid solution synthesized by different technological conditions, including XRD and electrochemical behavior were studied. The results showed that the optimum heat treatment technological condition was 750 C for 20 hour. As to different x values of LiNi1-xCoxO2 solid solution ,we found that electrochemical behaviors of LiNi0.6Co0.4O2 were better than the others. But obviously polarizations of LiNi1-xCoxO2 solid solution were occurred in the process of galvanostatic charge/discharge. The cyclic performances should be improved.3. LiNio.7Co0.3-xMxO2(M=Al, Mn) prepared by solid phase mixing reaction had the same crystal structures with LiNiO2 layered structure. It revealed that mixing Al to LiNi1-xCoxO2 composition can stabilize their layered structure, but the values of x should be less than 0.10; 750 C were the optimum temperature because that LiNi1-xCoxO2 composition prepared at this temperature showed better structure and electrochemical behavior;4. With x of mixing Mn increasing, the ratio of I(003)/I(104) decreased, the degree of order of cation increased. From the electrochemical behavior, we could conclude, compare to LiNi0.7Co0.3O2, LiNi0.7Co0.20Mn0.10O2 had higher charge-discharge platforms, more.