| 摘要 |
A negative electrode material for lithium ion secondary batteries includes core-shell composite particles prepared by covering the surface of a graphite powder with an amorphous carbon powder via a carbide of binder pitch, the graphite powder having an average particle diameter of 5 to 30 μm and an average lattice spacing d(002) of less than 0.3360 nm, and the amorphous carbon powder having an average particle diameter of 0.05 to 2 μm and an average lattice spacing d(002) of 0.3360 nm or more. A method to produce the negative electrode material includes mixing a graphite powder with pitch having a softening point of 70 to 250° C., adding an amorphous carbon powder to the resulting product, kneading the mixture while applying a mechanical impact to soften the pitch and carbonizing the pitch by heat treatment of the mixture at 750 to 2250° C. in a non-oxidizing atmosphere. |
