Patent ID: 8728668

Claim:
A negative electrode active material for a lithium ion rechargeable battery, comprising: three kinds of graphite powder A, B and C, having different hardnesses and shapes from each other, in a mixing ratio by weight of 30-60% graphite powder A, 20-50% graphite powder B and 10-30% graphite powder C, based on the total weight of graphite powder A+graphite powder B+graphite powder C=100%, wherein graphite powder A is obtained by pulverizing an artificial graphite block composed of coke and binder pitch, a relationship between press pressure P, in kN, and electrode density D, in g/cm 3 , is D=0.04 to 0.06 P, in a press pressure range of 5 to 20 kN, an average particle diameter D50 in a range of 10 to 20 microns and a D90/D10 ratio in a range of 5 to 7, graphite powder B has a D90/D10 ratio in a range of 2 to 4, is obtained by coating and impregnating spherical natural graphite with pitch, then baking and graphitizing, a relationship between press pressure P, in kN, and electrode density D, in g/cm3, is D=0.04 to 0.06 P, in a press pressure range of 5 to 20 kN and an average particle diameter D50 in a range of 10 to 20 microns, and graphite powder C is obtained by coating and impregnating spherical natural graphite with pitch, subsequently baking at a temperature of from 900 to 1300° C. without graphitizing, a relationship between press pressure P, in kN, and electrode density D, in g/cm3 is D=0.01 to 0.03 P, in a press pressure range of 5 to 20 kN and an average particle diameter D50 in a range of 10 to 20 microns.