| 摘要 |
A composite carbon material of negative electrode in lithium ion, which is made of composite graphite, includes a spherical graphite and a cover layer, wherein the cover layer is pyrolytic carbon of organic substance. Inserted transition metal elements are contained between layers of graphite crystal. Preparation of the negative electrode includes the steps of: crushing graphite, shaping to form a spherical shape, purifying treatment, washing, dewatering and drying, dipped in salt solution doped by transition metal in multivalence, mixed with organic matter, covering treatment, and carbonizing treatment or graphitization treatment. The negative electrode provides advantages of reversible specific capacity larger than 350 mAh/g, coulomb efficiency higher than 94% at first cycle, conservation rate for capacity larger than 8-% in 500 times of circulation.
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