| The Co-Ni-Mn lithium ion battery cathode materials have advantages of the cobalt acid lithium, manganese acid lithium and nickel acid lithium’s. And they are high cycle stability, high safety and large capacity. Its appearance provides a bright future for the lithium ion secondary battery. But itself also has some defects, and it still needs to improve.This experiment with Na OH as precipitant and ammonia as the complexing agent, using coprecipitation to prepare the layered structure Li Ni1/3Co1/3Mn1/3O2 cathode material. It used XRD, SEM and electrochemical performance testing means to test the materials, and found the optimization of the preparation of the Li Ni1/3Co1/3Mn1/3O2 cathode material. The optimal technological process was: under the condition of p H value of 11, coprecipitation preparation of the anode materials precursor, adding Li/M 1.05:1 lithium hydroxide into the precursors, 500℃ presintering 5h, 850℃ calcination 10 h. The initial discharge specific capacity of Li Ni1/3Co1/3Mn1/3O2 cathode material was 220.301 m Ah·g-1 at voltage from 2.0V to 4.8V and 0.1C ratio. After 20 times cycle, the discharge specific capacity of it was 197 m Ah·g-1. The first discharge specific capacity of Li Ni1/3Co1/3Mn1/3O2 were 182.6m Ah·g-1, 118.5m Ah·g-1 and 104.9m Ah·g-1 which were tested at 0.2C, 0.5C and 1C ratio respectively. The materials’ respective coulomb efficiency was: 98.89%, 97.25% and 98.98%. After 20 cycles, the cycle performance of material was better under different ratio. Discharge specific capacity of material were 169.1m Ah·g-1, 104.9m Ah·g-1, 89.60 m Ah·g-1 which were at 0.2C, 0.5C and 1C ratio respectively. After 20 cycle test, the charge and discharge volume efficiency of material were 94.71%, 91.53% and 87.26%.It had cladding, doping modification research for Li Ni1/3Co1/3Mn1/3O2 cathode material. It studied the different metal oxide(Mg O, Ti O2, Al2O3) coated for the preparation of the Li Ni1/3Co1/3-1/20Mn1/3M1/20O2(M=Mg、Ti、Al), and it tested the positive physical and electrochemical properties of composite materials. Results show that the coated Al2O3 preparation cathode material performance is the best, for the first time discharge specific capacity of cathode material can reach 264.5m Ah·g-1 which was tested under 0.1C and the efficiency can reach 95.69%. After 20 times cycle, the capacity of Al2O3 coated material kept the highest rate which was 92.5%. It studied the different amount of Al2O3 coated on the influence of the physical and electrochemical properties of the material. Research showed that when the amount of Al2O3 coated was 1/20, the performance of the material was the best. And the first discharge specific capacity of it was 264.5m Ah·g-1 at 0.1 C ratio. After 20 times’ charge and discharge cycle, the discharge of the material was 246.0m Ah·g-1 and the corresponding capacity remained at a rate of 93.01%. With using F- and Al3+ doping, it prepared the anode materials Li Ni1/3Co1/3-1/20Mn1/3Al1/20O2F0.05. The first charge and discharge specific capacity of the material were 222.6m Ah·g-1 and 213.4m Ah·g-1 which was tested at 0.1 C ratio and the voltage range from 2.0 V to 4.8 V. And the discharge of the material was 193.4m Ah·g-1, capacity remained at a rate of 90.62% after 20 times’ charge and discharge cycle. |
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