Patent ID: 7141229

Claim:
A process for manufacturing a graphite material for negative electrode of lithium secondary battery, which process comprises pulverizing green coke produced from coal- or petroleum-derived heavy oil by a delayed coker to an average particle diameter of 50 μm or less, carbonizing the pulverized green coke at 700–1500° C. to yield coke, adding one kind or more or boron or a compound thereof to the coke, graphitizing the resulting mixture, and controlling the particle size of the graphite material produced, wherein the coke possesses anisotropy due to flow texture, wherein the green coke after pulverization and/or carbonization is subjected to deagglomeration and/or classification to control the average particle diameter of the green coke in the range of 3–50 μm, wherein boron or the compound thereof is added in an amount of 0.1–5.0 wt % as boron, wherein the control of the particle size consists of passing the pulverized particles through a sieve with an opening of 10–120 μm to remove coarse particles, and wherein the graphite material comprises (a) a tap density of 0.95 g/cm 3 or more after tapping 20 times or 1.15 g/cm 3 more after tapping 300 times, and a BET specific surface area of 1.5 m 2 /g or less, and (b) a 10% cumulative particle diameter in the range of 2–12 μm, a 90% cumulative particle diameter in the range of 10–120 μm and an average particle diameter in the range of 5–100 μm.