| As a new generation cathode material, Lithium nickel oxide (LiNiO2) is a promising cathode candidate for its low cost and high energy density, showing an attractive prospect at minitype-portable electric sources and large-scale power supplies. LiNiO2 and its partially substituted compounds have been studied intensively as a cathode material to replace the presently used LiCoO2. However, the electrochemical properties of LiNiO2 have been greatly affected by the generation of stiochiometric deviation and cation mixing during preparation, and this has become technical problems unsolved world-widely yet.For a solution to these problems, extensive studies have been carried out on the preparation conditions of Co-doped compounds of LiNi1.xCoxO2 in the paper. The sample LiNio.7Coo.3O2, synthesized in air atmosphere but not in oxygen atmosphere directly, shows more satisfactory performance than the one presently prepared in oxygen. The lattice parameters of the hexagonal layered LiCoo.3Nio.7O2 (space group R3m) with an a-NaFeO2 structure are a=0.2870nm, c=1.4209nm. It has an ideal layered structure and the ratio of 1003/1104 is above 1.40. Its initial discharge capacity is 167mAh/g, its initial discharge efficiency is over 90%, and the 40th discharge capacity only deceases 4%, showing good electrochemical stabilities. The experience of using air atmosphere instead of oxygen to prepare LiNi1-xCoxO2 successfully has developed an improved and cost effective method, which makes the industrialized production of LiNi1-xCoxO2 becoming possible.Differed from present cathode materials research thought and method, we have brought forward the idea of emphasizing on the study of the precursor. It has discovered for the first time that the precursor B-Ni1-xCox(OH)2, with pluffy and dendritic morphology, high specific surface area and low tap density, is the best starting material to produce LiNi1-xCoxO2 materials, but not the presently thought that high density and spherical particle of Ni(OH)2 is fitting for the preparation of Ni-cathode materials. Using our own precursor can greatly reduce the degree of cation mixing; improve the electrochemical properties of the aimed materials.The "controlled crystallization method" has been used to prepare the precursor, and the relations between the preparation condition and the chemical activity, crystal structure have been investigated. The results indicate that the process conditions including the type of Ni-salts, pH, and ammonia addition are important for the preparation of the precursor. The XRD analysis find out that the precursor with a perfect crystal form and ordered cell structure, has a lower chemical activity, while the one with much crystal deficiency, and wider width of (hOl) in XRD patterns has a higher chemical activity.A new synthetic method, Like Sol Impregnation Method, was used to synthesis LiCoxNi1-xO2 compounds. Using this method, reactants Ni1-xCox(OH)2 and LiOHH2O can be maximizingmixed through the organic reagent impregnating and the original particle pattern and reactivity of the precursor Ni1-xCox (OH) 2 can be hold. The results indicate that the method has avoids the shortage brought by classical method. The completely mixing of the raw materials made by this method has greatly increased the interionic diffusion velocity and diffusion space at high temperature solid-state reaction; make the reaction at lower temperature and shorter time reach reaction balance. And the resulted sample has an excellent layered structure and the cation mixing and nonstoichiometric products are effectively restrained. Technological conditions of the cathode material LiNi1-xCoxO2 using Like Sol Impregnation Method at air atmosphere have been investigated systematically.The structure and cycling performance of the sample LiNio.7Coo.3O2 obtained at optimal conditions have been further studied too. The results indicates that the sample exhibits good electrochemical properties when cycled at low current density, and the material has little volume changes, showing good stru...
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