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

Layered structral LiNio.7Coo.3O2 positive materials and LiNio.7Coo.3=xAlxO2 materials for rechargable lithium-ion batteries were prepared by traditional solid phase and liquid methods. Measurements such as XRD. SEM. microelectrode cyclic voltammetry. galvamostative charge/discharge test were introduced to study the crystal structures and electrochemical performances of the materials prepared. We arrived the conclusions as following:1 .After comparision of the structures and electromechical properties of LiNi0.7Coo.3O2 positive materials prepared by solid and liquid phase methods espectively, we came to realize that, it was more easier to get pure LiNio.7Co0.33O2 materials by liquid methods, and the charge/discharge capacity . cyclic performances are superial to that materials prepared by solid phase methods.2.Comparing the structrues and electrochemical properties of LiNio.7Co0.33O2 solid solutions under different heat treatment processes, we could see that, with the rising of the sintering temperature and the extension of the sintering period, the crystal of the products appeared more and more perfect, but the electrochemical performances were't determined to be good. As to solid phase method, 800 癈 for about 20 hours was the optimum heat treatment process, and about 20 hours under750 for liquid methods considering of the cost and efficiency.3. The structrues and electrochemical properties of LiNi0.7.7Co0.3O2 positive materials prepared by three kinds of liquid methods were studied, and samples prepared by homogeneous precipitation were proved to have the best electrochemical properties. Samples introducing nickel powder to be Ni source had perfect crystal structures, but the discharge capacity was far from satisfaction. Materials prepared by simultaneous precipitation had excellent combination properties, while the technology was more complex than others, and it was not convinent to control the pH value, which would bring inconvinences to industrial process.4. LiNio.7Co.3-AlO2 prepared by solid phase method had the same crystal structures with layered LiNiO. It was revealed that doping Al to LiNioCooO compounds will stablize the layered structure, but the value of 'x' should be less than 0.10. 80C was the optimum synthesis temperature, and materials generated under the condition had larger ratio value of I and higher degree of order of cation, which leading to stable structures. But the electrochemical properties didn't have dramatic elevation, and further investigations were expected.