Negative electrode material for use in lithium-ion secondary battery and process for producing the same

摘要

A negative electrode material for use in lithium-ion secondary batteries, comprising milled pitch-based graphite fibers (A) obtained by graphitization at 2400 DEG C or higher and milled pitch-based carbon fibers (B) obtained by carbonization at 550 to 1300 DEG C. In this negative electrode material, it is preferred that both the milled pitch-based graphite fibers (A) and the milled pitch-based carbon fibers (B) have an average particle size of 10 to 30 mu m, that the ratio of milled pitch-based carbon and graphite fibers having a particle size of 5 mu m or less to all the milled pitch-based carbon and graphite fibers is not greater than 10% by weight and that the milled pitch-based graphite fibers (A) and the milled pitch-based carbon fibers (B) are blended at a weight ratio (A/B) of 95/5 to 40/60. A negative electrode which has a large capacity at the time of having been stabilized, exhibits a high charge and discharge efficiency at the initial stage and is excellent in charge and discharge cycle characteristics can be provided by the blending of milled pitch-based carbon fibers with milled pitch-based graphite fibers.