| 摘要 |
PROBLEM TO BE SOLVED: To provide a negative electrode material formed of graphitic powder having high crystallinity and a small specific surface area which provides a lithium ion secondary battery having a high utilizing ratio of electrolyte or Li and a large discharge capacity by constituting the negative electrode material of a specified graphitic carbon powder. SOLUTION: This negative electrode material is formed of a non-spherical graphitic carbon powder having a specific surface area of 1m<2> /g or less and an interlayer distance d002 of 3.352Åor less. The graphitic carbon powder is obtained by thermally treating, for example, tar and/or pitch (e.g. coal tar rich in aromatic content) at 430-520 deg.C, preferably under a reduced pressure of 10-100Torr, to prepare a bulk mesophase having an optically anisotropic microstructure in which the powder residual quantity in fusing property test is 5wt.% or less, heating and carbonizing it to 700-1100 deg.C in the atmosphere of an inert gas after pulverization to about several μ-50μ, and further baking and graphitizing it at 2500 deg.C or more. |
