| 摘要 |
A nonaqueous-electrolyte secondary cell having a negative electrode made of a carbon material which can be doped with lithium and from which dopant lithium can be removed, a positive electrode, a nonaqueous electrolyte prepared by dissolving an electrolyte in a nonaqueous solvent. The carbon material is a pulverized graphite material having a true density of 2.1 g/cm<3> and a bulk density of 0.4 g/cm<3>. This graphite material is such a powder that the mean value of the shape parameter (x) expressed by the following formula is below 125.x = (L/T) x (W/T) where x is the shape parameter of the powder, T is the thickness of powder at the thinnest part, L is the length of powder in the length direction. W is the length of powder in the direction normal to the length direction. The graphite material has a specific surface area of 9 m<2>/g and a cumulative 10 % grain size of 3 mu m, a cumulative 50 % grain size of 10 mu m, and a cumulative 90 % grain size of 70 mu m in the particle size distribution found by a laser diffraction method. Such a graphite material powder is prepared by, for example, graphitizing a molded body of a carbon material by heat treatment and grinding the graphitized molded body. The mean fracture strength value of the particles of the graphitic material is greater than 6.0 kgf/mm<2>. |
