A Ctab-assisted Hydrothermal Synthesis Of Cathode Material LiNi_1/3Co_1/3Mn_1/3O₂ For Lithium Battery

Since Lithium-ion battery was commercialized in 1990, with the development of science and technology, a rising performance requirement of lithium-ion battery was required. The Li CO2 lithium-ion battery could not meet the demand of users. Therefore,development of new type of lithium battery cathode materials becomes a significant key to improve the performance of the lithium battery. Li Ni1/3Co1/3Mn1/3O2 integrates the advangages of Li Co O2, Li Ni O2 and Li Mn O2, and has a better overall performance than any one-element cathode material due to the synergies.In this thesis, we considered the principle of the co-precipitation method,hydrothermal method and solid-phase reaction process to synthesize the lithium-ion batteries material Li Ni1/3Co1/3Mn1/3O2, and studied influence of the preparation process of the hydrothermal, reaction temperature, reaction time the concentration of CTAB.After testing the performance of the material using the XRD、SEM、EDS test methods and battery test system, we optimized condition to prepare the Li Ni1/3Co1/3Mn1/3O2 material.a) According to the study of the mechanism of ammonia complex and comparing the experiments, we found that ammonia plays little role in this hydrothermal method,although it has a great benefit for traditional co-precipitation methods. Complexation ammonia can not adjust the supersaturation of formed precursor in the hydrothermal reaction.b) The temperature of hydrothermal reaction has a great influence on the crystal growth process. When the hydrothermal reaction temperature is too low, the growth process is supresssed, and Li Ni1/3Co1/3Mn1/3O2 can not form a complete layered crystal structure.According to comparison of experimental results, the optimal reaction temperature of the hydrothermal reaction is 170 ℃. At this temperature, the crystal growth process is promoted and matches with crystal nucleation rate. A high temperature condition favors the hydrolysis of CTAB. Increasing the surfactant concentration in the solution of ions is conducive to the synthesis of a special morphology comparative experiment material.c) With the gradual extension of the hydrothermal reaction time, crystalline Li Ni1/3Co1/3Mn1/3O2 material gradually increased, layered structure was gradually improved. We found that after heating 12 h, the microstructure and morphology of the material are collapsed. With the reaction time of increases, the crystallization degree of Li Ni1/3Co1/3Mn1/3O2 instead becomes worse. To change the concentration of the CTAB,we can synthesize different Li Ni1/3Co1/3Mn1/3O2 materials with different morphologies.