Negative electrode material for lithium-ion secondary battery, method for manufacturing negative electrode material for lithium-ion secondary battery, negative electrode material slurry for lithium-ion secondary battery, negative electrode for lithium-ion secondary battery, and lithium-ion secondary battery
A negative electrode material for a lithium-ion secondary battery, in which the negative electrode material includes a composite particle including a spherical graphite particle and plural graphite particles that have a compressed shape and that aggregate or are combined so as to have nonparallel orientation planes, and the negative electrode material has an R-value in a Raman measurement of from 0.03 to 0.10, and has a pore volume as obtained by mercury porosimetry of from 0.2 mL/g to 1.0 mL/g in a pore diameter range of from 0.1 μm to 8 μm.
1. A negative electrode material for a lithium-ion secondary battery, the negative electrode material comprising a composite particle including a spherical graphite particle and a plurality of graphite particles that have a compressed shape and that aggregate or are combined so as to have nonparallel orientation planes, and the negative electrode material having an R-value in a Raman measurement of from 0.03 to 0.10, and having a pore volume as obtained by mercury porosimetry of from 0.2 mL/g to 1.0 mL/g in a pore diameter range of from 0.1 μm to 8 μm.
2. The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein a specific surface area of the negative electrode material, as measured by a BET method, is from 1.5 m 2 /g to 6.0 m 2 /g.
3. The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein a saturated tap density of the negative electrode material is from 0.8 to 1.2 g/cm 3 .
4. The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein of the negative electrode material has an intensity ratio (P 2 /P 1 ) of a diffraction peak (P 2 ) for a (101) plane of a rhombohedral crystal structure to a diffraction peak (P 1 ) of a (101) plane for a hexagonal crystal structure in a CuKα X-ray diffraction pattern is 0.35 or less.
5. The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein the spherical graphite particle has a circularity of 0.8 or higher.
6. A method of manufacturing the negative electrode material for a lithium-ion secondary battery according to claim 1 , the method comprising steps of:
(a) mixing a graphitizable aggregate or graphite with a graphitizable binder, a graphitization catalyst, and a spherical graphite particle; and
(b) calcining the mixture.
7. The method of manufacturing the negative electrode material for a lithium-ion secondary battery according to claim 6 , comprising, between the steps (a) and (b), at least one step selected from the group consisting of (c) molding the mixture and (d) subjecting the mixture to a heat treatment.
8. A negative electrode material slurry a lithium-ion secondary battery, the negative electrode material slurry comprising:
the negative electrode material for a lithium-ion secondary battery according to claim 1 ;
an organic binder; and
a solvent.
9. A negative electrode for a lithium-ion secondary battery, the negative electrode comprising:
a current collector; and
a negative electrode material layer formed on the current collector and comprising the negative electrode material for a lithium-ion secondary battery according to claim 1 .
10. A lithium-ion secondary battery, comprising:
a positive electrode;
an electrolyte; and
the negative electrode for a lithium-ion secondary battery according to claim 9 .