Negative electrode for lithium secondary battery and lithium secondary battery

1. A negative electrode for a lithium secondary battery comprising:

a layer of a mixture containing graphite powder that has an average particle diameter in a range of 1 to 100 μm, a crystallite size Lc (002) in a C-axis direction of a crystal of at least 500 Å, a specific surface area of at most 8 m 2 /g, and an aspect ratio of at most 5, and an organic binder on a current collector,

wherein a diffraction intensity ratio (002)/(110) measured by X-ray diffractometry of the layer of the mixture is at most 500, and

wherein the graphite powder is a secondary power where a plurality of flat primary powders is aggregated or bonded so as to be non-parallel in orientation planes and individual flat primary powders have a size in a range of 1 to 100 μm and an aspect ratio of 100 or less.

2. A method of manufacturing the negative electrode for a lithium secondary battery comprising a layer of a mixture containing graphite powder that has an average particle diameter in a range of 1 to 100 μm, a crystallite size Lc (002) in a C-axis direction of a crystal of at least 500 Å, a specific surface area of at most 8 m 2 /g, and an aspect ratio of at most 5, and an organic binder on a current collector, wherein a diffraction intensity ratio (002)/(110) measured by X-ray diffractometry of the layer of the mixture is at most 500, the method comprising:

blending a graphitizable aggregate or graphite that has an average particle diameter in the range of 1 to 80 μm and an aspect ratio in the range of 1.2 to 500 and a graphitizable binder, followed by pulverizing:

after said pulverizing, blending the pulverized material and 1 to 50% by weight of a graphitizing catalyst, followed by sintering to obtain graphite powder;

subsequently, adding an organic binder and a solvent to the graphite powder, followed by blending;

coating the mixture on a current collector, followed by drying to remove the solvent; and

pressurizing to integrate to obtain a negative electrode for a lithium secondary battery.

3. A lithium secondary battery comprising:

a negative electrode for a lithium secondary battery prepared according to a manufacturing method of claim 2 ; and

a positive electrode containing a lithium compound.

4. The lithium secondary battery of claim 3 , wherein the lithium compound contains at least Ni.

5. The lithium secondary battery of claim 4 , wherein the lithium compound contains at least Ni.

6. A graphite powder that is used in a negative electrode for a lithium secondary battery, which has a layer of a mixture containing graphite powder and an organic binder, the layer of the mixture having a diffraction intensity ratio (002)/(110) measured by X-ray diffractometry of 500 or less, wherein the graphite powder is a secondary powder that has an average particle diameter in a range of 1 to 100 μm, a crystallite size Lc (002) in a C-axis direction of a crystal of 500 Å or more, a specific surface area of 8 m 2 /g or less and an aspect ratio of 5 or less, and where a plurality of flat primary powders is aggregated or bonded so as to be non-parallel in orientation planes, wherein each of the flat primary powders has a size in a range of 1 to 100 μm and an aspect ratio of 100 or less.

7. A lithium secondary battery comprising:

a negative electrode for a lithium secondary battery that uses the graphite powder of claim 6 ; and

a positive electrode containing a lithium compound.

8. The lithium secondary battery of claim 7 , wherein the lithium compound contains at least Ni.

9. A graphite powder that is used in a negative electrode for a lithium secondary battery, which has a layer of a mixture containing graphite powder and an organic binder, the layer of the mixture having a density in the range of 1.5 to 1.95 g/cm 3 , a diffraction intensity ratio (002)/(110) measured by X-ray diffractometry of 500 or less, wherein the graphite powder is a secondary powder that has an average particle diameter in a range of 1 to 100 μm, a crystallite size Lc (002) in a C-axis direction of a crystal of 500 Å or more, a specific surface area of 8 m 2 /g or less and an aspect ratio of 5 or less, and where a plurality of flat primary powders is aggregated or bonded so as to be non-parallel in orientation planes, wherein each of the flat primary powders has a size in a range of 1 to 100 μm and an aspect ratio of 100 or less.

10. The lithium secondary battery comprising:

a negative electrode for a lithium secondary battery that uses the graphite powder of claim 9 ; and

a positive electrode containing a lithium compound.