Patent ID: 8153303

Claim:
A negative electrode material for lithium ion secondary batteries comprising 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, 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, the composite particles having (1) a specific surface area by nitrogen adsorption of 4.2 to 5.9 m 2 g, (2) an average particle diameter of 7 to 40 μm, and (3) a Raman spectrum intensity ratio of I1360/I1580 of 0.6 or more.