Patent ID: 8501047

Claim:
A mixed carbon material comprising carbon material A which has cores of graphite powder having carbon adhered to or coated on the surface of the cores, and carbon material B which is graphite powder, wherein the carbon which is adhered to or coated on the surface of the cores of carbon material A is turbostratic carbon, the compressibility which is expressed by the compressed density defined below is 1.60-1.78 g/cm 3 for carbon material A, 1.75-1.85 g/cm 3 for carbon material B and 1.67 -1.79 g/cm 3 for the mixed carbon material, and the compressibility of carbon material A is less than the compressibility of carbon material B, said compressed density being the density (g/cm 3 ) when 1.00 grams of a material are packed into a cylindrical mold having an inner diameter of 15 mm and compressed by applying a force of 8.7 kN followed by reducing the force to 0.15 kN, the average particle diameter of carbon material B is less than or equal to the average particle diameter of carbon material A, and the mixing ratio of carbon material A to carbon material B (carbon material A/carbon material B) is from 1 to 9 parts of carbon material A to 1 part of carbon material B as a mass ratio.