Abstract: A negative electrode active material for a secondary battery including an artificial flake graphite A and an artificial lump graphite B and having a ratio D50(A)/D50(B) of 50% particle diameter D50(A) of the artificial flake graphite A in a volume-based particle size distribution to 50% particle diameter D50(B) of the artificial lump graphite B in a volume-based particle size distribution is more than 0.6 and less than 1.0. The artificial flake graphite A has a surface roughness R of not less than 2.8 and not more than 5.1, the artificial lump graphite B has a surface roughness R of not less than 6.0 and not more than 9.0, and a ratio B/(A+B) of a mass of the artificial lump graphite B to the total mass of the artificial flake graphite A and the artificial lump graphite B is not less than 0.03 and not more than 0.30.

Abstract: Composite graphite particles, including a core material composed of artificial graphite and a coating material for coating the core material. The coating material includes a non-powdery amorphous carbon material and a powdery conductive carbon material. The ratio of the mass of the non-powdery amorphous carbon material to the mass of the core material is 0.2 to 3.8 mass %, and the ratio of the mass of the powdery conductive carbon material to the mass of the core material is 0.3 to 5.0 mass %. Also disclosed is a method for producing the composite graphite particles, a paste containing the composite graphite particles, an electrode sheet including a laminate of a current collector and an electrode layer containing the composite graphite particles, and a lithium ion secondary battery including the electrode sheet as a negative electrode.

Abstract: A graphite material, including high crystallinity graphite and spherical graphite, in which high crystallinity graphite: (1) a rhombohedral crystal ratio by X-ray diffractometry is 0.02 or less, (2) Lc is 90 nm or more, (3) when a pressure of 1 GPa for 10 seconds is applied to the high crystallinity graphite, the increment rate of the BET specific surface area after applying the pressure to the BET specific surface area before applying the pressure is 90% or less, and (4) D10 is 5.0 ?m or more; and in which spherical graphite: (1) a median of the circularity is 0.90 or more, and (2) a tapping density is 1.20 g/cm3 or more; and the ratio by mass of the high crystallinity graphite and the spherical graphite is 95:5 to 40:60; an electrode using the graphite material as an electrode active material; and a lithium ion secondary battery using the electrode.

Abstract: A method for manufacturing a graphite powder for a negative electrode material for a lithium-ion secondary battery, which includes a process of pulverizing a graphite precursor, and subjecting a mixture of the pulverized graphite precursor and an alkaline compound to graphitization treatment by heating the mixture at 2,800 to 3,500° C. Also disclosed is a graphite powder obtained by the manufacturing method, a negative electrode for a lithium-ion secondary battery containing the graphite powder and a lithium-ion battery provided with the negative electrode.