Study On Surface-modified Spheroidized Natural Graphite As Cathode Materials In Lithium Ion Batteries

Graphite is a good anode material of lithium batteries. It includes natural graphite and artificial graphite. Artificial graphite is the main anode material of lithium batteries in China for its stable performance, but the cost is higher. Although the performances of natural graphite in China are different because of its producing area and processing technology, the electrochemical performance in LIB (Li-ion batteries) as cathode materials is similarly rather poor, the irreversible capacity is rather high and the cycle life is too short due to the flake structure, which seriously limits its application. In order to improve the performance, many factories have tried hard and now some of them have already obtained the breakthrough of the physical mould of the natural graphite, and there is little difference in the main physicochemical properties between the product and artificial graphite. But it can not be used yet without being modified because of high irreversible capacity and poor cycle life.In this thesis, a kind of spheroidized natural graphite was used as the raw material, which was coated with copper or nickel by electroless plating, and with pitch or resin by liquid immersion respectively. The preparing process is designed by orthogonal test.The structure and the morpholygy are investigated. The electrochemical behavior of the graphite samples was studied in a three-electrode system by cyclic voltammetry (CV)...