| 摘要 |
PROBLEM TO BE SOLVED: To stably manufacture a graphite powder suitable as a material for negative electrodes of lithium ion secondary batteries which has a discharge capacity of >=340 mAh/g which is a value close to the theoretical capacity and a charging and discharging efficiency of around 95% or larger, and allows little decrease in its charging and discharging efficiency even at large current discharging or low-temperature discharging. SOLUTION: Tar and/or pitch is heated under a pressure of from 200 to 700 Torr at from 400 to 600 deg.C to obtain a bulk mesophase carbon with a highly developed anisotropy. This bulk mesophase carbon is subjected to grinding, carbonization and graphitization to manufacture a graphite powder. Grinding is conducted prior to graphitization through at least one means chosen from high-speed grinding and high-shear grinding, to yield a powder preferably having an aspect ratio of <=2.0. This process ensures the manufacture of a highly crystalline graphite powder having a small specific surface area and many Li ion- invasion sites.
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