Graphite anode active material for use in lithium secondary battery
View Patent ↗By a method that includes coking a residue resulting from distillation of crude oil under reduced pressure and having API gravity of 1 to 5, an asphaltene content of 10 to 50%, a resin content of 5 to 30%, and a sulfur content of 1 to 12% to obtain coke, pulverizing the coke to obtain a carbon powder, and heating the carbon powder at 1000 to 3500 deg C., a graphite anode active material for use in a lithium secondary battery is obtained that has, in X-ray powder diffraction, d 002 of not smaller than 0.3354 nm and not greater than 0.337 nm, Lc(004) of smaller than 100 nm, La(110) of not smaller than 100 nm, and a half width of the peak of a plane (101) at a diffraction angle (2θ) of 44 degrees to 45 degrees of not smaller than 0.65 degree.
1. A graphite anode active material for use in a lithium secondary battery wherein the graphite anode active material is, according to X-ray powder diffraction,
not smaller than 0.3354 nm and not greater than 0.337 nm in d 002 ,
smaller than 100 nm in Lc(004),
not smaller than 100 nm in La(110), and
not smaller than 0.65 degree in a half width of the peak of a plane (101) at a diffraction angle (2θ) of 44 degrees to 45 degrees.
2. The graphite anode active material for use in a lithium secondary battery according to claim 1 wherein a ratio I(100)/I(101) of peak intensity in X-ray powder diffraction is not lower than 0.7 and not higher than 1.
3. The graphite anode active material for use in a lithium secondary battery according to claim 1 wherein a layer has a ratio I(110)/I(004) of peak intensity of not lower than 0.2 measured by X-ray diffraction, the layer having density of not lower than 1.5 g/cm 3 and not higher than 1.6 g/cm 3 formed by applying a mixture of the anode active material and a binder to copper foil to be subjected to drying and pressure molding.
4. The graphite anode active material for use in a lithium secondary battery according to claim 1 wherein a BET specific surface area is not greater than 5 m 2 /g and D 50 referring to a volume average particle diameter is not smaller than 3 μm and not greater than 30 μm.
5. The graphite anode active material for use in a lithium secondary battery according to claim 1 wherein a half width of the peak of a plane (101) at a diffraction angle (2θ) of 44 degrees to 45 degrees in X-ray powder diffraction is not smaller than 0.65 degree and not greater than 2 degrees.
6. The graphite anode active material for use in a lithium secondary battery according to claim 1 wherein the graphite anode active material is surface-treated.
7. The graphite anode active material for use in a lithium secondary battery according to claim 1 wherein the graphite anode active material is surface-treated with pitch having a softening point of 200 to 350 deg C. and a fixed carbon content of 50 to 80% by mass.
8. The graphite anode active material for use in a lithium secondary battery according to claim 7 wherein D 50 referring to a volume average particle diameter of the pitch is 1 μm to 10 μm.
9. The graphite anode active material for use in a lithium secondary battery according to claim 7 wherein the pitch is optically isotropic.
10. A method for producing the graphite anode active material for use in the lithium secondary battery according to claim 1 comprising:
coking a residue resulting from distillation of crude oil under reduced pressure and having API gravity of 1 to 5, an asphaltene content of 10 to 50%, a resin content of 5 to 30%, and a sulfur content of 1 to 12% to obtain coke,
pulverizing the coke to obtain a carbon powder, and
heating the carbon powder at 1000 to 3500 deg C.
11. The method according to claim 10 further comprising performing surface treatment by mechanofusion or a wet process.
12. The method according to claim 10 wherein a water content of the coke is not higher than 1.0%.
13. An anode for use in a lithium secondary battery comprising the graphite anode active material for use in a lithium secondary battery according to claim 1 .
14. The anode for use in a lithium secondary battery according to claim 13 further comprising a vapor grown carbon fiber with a fiber diameter of not smaller than 5 nm and not larger than 0.2 μm.
15. A lithium secondary battery comprising the anode for use in a lithium secondary battery according to claim 13 .
16. The lithium secondary battery according to claim 15 comprising at least one solvent selected from a group consisting of ethylene carbonate, diethyl carbonate, dimethyl carbonate, methylethyl carbonate, propylene carbonate, butylene carbonate, ganma-butyrolactone, and vinylene carbonate.
17. A transportation, a power-generating system, or an electrical or electronic equipment comprising the lithium secondary battery according to claim 15 .