| Rapid progresses have been made in the research on lithium ion batteries due to its superior properties for recent years. These properties, however, are greatly affected by the selection and preparation of the materials, such as the electrode materials, the electrolytes and the separators, particularly the cathode materials. The research on cathode materials is focused on layered compounds LixMO2 and spinel compounds LixM2O4 (M=Co, Ni, Mn, V and other transition metal ions). The shortage of the cobalt resources results in the high price of LixCoO2 as cathode material. The cathode material of LixNiO2 with perfect crystal structure is very difficult to be prepared. The capacity of LixMn2O4 falls down rapidly with time in practice. Lithium vanadium oxides display high capacity and low price as cathode materials for lithium ion batteries. Lithium vanadium oxides, however, are hard to be synthesized because of the various valences of vanadium. If the factors of price and comprehensive electrochemical properties are considered, the cathode materials of (lithium) vanadium oxides should be recognized as the most potential cathode materials for lithium ion batteries.In this paper, the preparing technological parameters, formation mechanism and structures of (lithium) vanadium oxides (nanocrystalline VO2, amorphous V2O5, layered Li1+xV3O8 and inverse spinel LiNiVO4) are systematically studied and discussed, and some properties of the products are measured as cathode materials for lithium ion batteries. The main results are as follows:(1) Nanocrystalline VO2 has been successfully synthesized by a solution chemical reaction method in normal temperature and pressure. The procedure involves V2O5 reacts with KOH to form K3VO3 in water and then K3VO3 is reduced with KBH4 around pH=4 forming VO2 precipitation in aqueous. The factors, such as reactant concentration, medium acidity, stirring speed, washing and drying temperature, directly influence purity, structure and yield of the product. The formation mechanism of the product is discussed and the preparation parameters are optimized. Under the optimum preparation conditions, the particle dimension of the resultant VO2 synthesized is 0.5 m, the yield is more than 90% and the purity is 99%.(2) Amorphous V2O5 has been successfully synthesized by an inorganic sol-gel method. The formation mechanism of the sol is analyzed and the influence of thepreparation parameters on the purity and structure of the product is also discussed. The melting temperature, time, preparation of the sol and dry condition of the gel are the key factors affecting the qualities of amorphous V2O5. The experimental results show that the resultant amorphous V2O5 under the optimum preparation conditions has high purity and large specific surface, which is an ideal active cathode material for lithium ion battery.(3) Layered Li1+xV3O8 has been synthesized at low temperature by a citric acid complex method. The synthesis conditions affecting the purity and structure of the product are discussed and the formation mechanism of the resultant is analyzed. The preparation parameters are studied and optimized. Comparing with conventional solid state reaction, the temperature of this method is reduced from around 700癈 to 450癈 and the time is shortened from more than 24 hours to 20 hours. The reaction process is smooth and the contents of lithium and vanadium are not lost during preparation processing, which conduced that the expected Li1+xV3O8 can be easily prepared. Comparing with other wet methods, the technical processing of this one is simple and there is no restriction for the raw materials. The product has perfect-layered structure and high purity, which is favorable to improve its electrochemical properties.(4) Inverse spinel LiNiVO4 has been successfully synthesized by citrate complex sol-gel method. In the preparation process of LiNiVO4, the main factors affecting the structure and purity of the product are the ratio of reactants, the formation process of the sol, the de...
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