| abstract |
To provide a mixed carbon material for a lithium ion secondary battery having both rapid charge / discharge characteristics and high cycle characteristics. A negative electrode active material comprising the following carbon material A and carbon material B. (Carbon material A) A multi-layer structure carbon material containing graphite particles and amorphous carbon covering the surface thereof, with an interplanar spacing (d002) by X-ray diffraction method of 3.37 mm or less, Lc of 900 mm or more, tap density 0.8 g / cm 3 or more, a carbon material peak intensity ratio R value in the vicinity of 1360 cm -1 to the peak intensity near 1580 cm -1 in the argon ion laser Raman spectrum is 0.25 to 0.6. (Carbon material B) X-ray diffraction plane spacing (d002) is 3.37 mm or less, Lc is 900 mm or more, tap density is 0.8 g / cm 3 or more, and peak intensity around 1580 cm −1 in an argon ion laser Raman spectrum. Carbon material whose peak intensity ratio R value in the vicinity of 1360 cm −1 is 0.11 to 0.2. [Selection figure] None |