Anode active material for use in lithium secondary battery
View Patent ↗An anode active material for use in a lithium secondary battery including a mixture of graphite I that has, according to 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 and another graphite so as to have, according to X-ray powder diffraction, d 002 of not smaller than 0.3354 nm and not greater than 0.337 nm, Lc(004) of not smaller than 80 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 0.5 degree.
1. An anode active material for use in a lithium secondary battery which comprises a mixture of two or more species of graphite, in which the mixture is, according to X-ray powder diffraction,
not smaller than 0.3354 nm and not greater than 0.337 nm in d 002 ,
not smaller than 80 nm in Lc(004),
not smaller than 100 nm in La(110), and
not smaller than 0.5 degree in a half width of the peak of a plane (101) at a diffraction angle (2θ) of 44 degrees to 45 degrees,
wherein one of the graphite species constituting the mixture of two or more species of graphite is graphite I in which the graphite I 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, and
wherein one of the graphite species is graphite II in which the graphite II is, according to X-ray powder diffraction,
not smaller than 0.3354 nm and not greater than 0.337 nm in d 002 ,
not smaller than 100 nm in Lc(004),
not smaller than 100 nm in La(110), and
not greater 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 anode active material for use in a lithium secondary battery according to claim 1 wherein the anode active material has a ratio I(100)/I(101) of peak intensity in X-ray powder diffraction that is not lower than 0.6 and not higher than 1.
3. The anode active material for use in a lithium secondary battery according to claim 1 wherein a layer comprising the anode active material has a ratio I(110)/I(004) of peak intensity of not lower than 0.1 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 anode active material for use in a lithium secondary battery according to claim 1 wherein the anode active material has a BET specific surface area that 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 anode active material for use in a lithium secondary battery according to claim 1 wherein the graphite I has a ratio I(100)/I(101) of peak intensity in X-ray powder diffraction of not lower than 0.7 and not higher than 1.
6. The anode active material for use in a lithium secondary battery according to claim 1 wherein the graphite I has a BET specific surface area of not greater than 5 m 2 /g and D 50 referring to a volume average particle diameter of not smaller than 3 μm and not greater than 30 μm.
7. The anode active material for use in a lithium secondary battery according to claim 1 wherein the content of the graphite I in the anode active material is not less than 40% by mass and not more than 90% by mass.
8. The anode active material for use in a lithium secondary battery according to claim 1 wherein the graphite II 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.
9. The anode active material for use in a lithium secondary battery according to claim 8 wherein D 50 referring to a volume average particle diameter of the pitch is 1 μm to 10 μm.
10. The anode active material for use in a lithium secondary battery according to claim 8 wherein the pitch is optically isotropic.
11. The anode active material for use in a lithium secondary battery according to claim 1 wherein the graphite II is natural graphite that is processed into a sphere.
12. The anode active material for use in a lithium secondary battery according to claim 1 wherein the graphite II is artificial graphite made from mesophase pitch as a raw material.
13. The anode active material for use in a lithium secondary battery according to claim 1 wherein the content of the graphite II in the anode active material is not less than 10% by mass and not more than 60% by mass.
14. An anode for use in a lithium secondary battery comprising the anode active material for use in a lithium secondary battery according to claim 1 .
15. The anode for use in a lithium secondary battery according to claim 14 further comprising a vapor grown carbon fiber with a fiber diameter of not smaller than 5 nm and not larger than 0.2 μm.
16. A lithium secondary battery comprising the anode for use in a lithium secondary battery according to claim 14 .
17. A transportation, a power-generating system, or an electrical or electronic equipment comprising the lithium secondary battery according to claim 16 .