Negative electrode for lithium ion secondary battery, and lithium ion secondary battery
A negative electrode for a lithium ion secondary battery, the negative electrode including a negative electrode active material, a fine graphite material, a conductive aid, and a binder, wherein the mass ratio of the fine graphite material to the conductive aid is in the range from 1 to 10, and the average particle diameter (median diameter D 50 ) of the fine graphite material is smaller than the average particle diameter of the negative electrode active material, and in the range of 1 to 15 μm.
1. A negative electrode for a lithium ion secondary battery, the negative electrode comprising a negative electrode active material, a fine graphite material, a conductive aid, and a binder,
wherein a mass ratio of the fine graphite material to the conductive aid is in a range from 1 to 10, and
an average particle diameter (median diameter D 50 ) of the fine graphite material is smaller than an average particle diameter (median diameter D 50 ) of the negative electrode active material, and in a range of 1 to 15 μm.
2. A negative electrode for a lithium ion secondary battery, the negative electrode comprising a negative electrode active material, a fine graphite material, a conductive aid, and a binder,
wherein the fine graphite material includes a particle contacting with a particle of the negative electrode active material, or a particle contacting with a particle of the conductive aid contacting with a particle of the negative electrode active material, with an electroconductive path formed between particles of the negative electrode active material via the particle of the fine graphite material,
a mass ratio of the fine graphite material to the conductive aid is in a range from 1 to 10, and
an average particle diameter (median diameter D 50 ) of the fine graphite material is smaller than an average particle diameter (median diameter D 50 ) of the negative electrode active material, and in a range of 1 to 15 μm.
3. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein a ratio of the average particle diameter (D 50 ) of the fine graphite material, Db, to the average particle diameter (D 50 ) of the negative electrode active material, Da, Db/Da, is in a range of 0.2 to 0.7.
4. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein the average particle diameter (D 50 ) of the negative electrode active material is in a range of 10 to 30 μm.
5. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein a ratio of a particle diameter at 90 cumulative % in a cumulative distribution (D 90 ) to the average particle diameter (D 50 ), D 90 /D 50 , of the negative electrode active material is 1.5 or smaller.
6. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein a ratio of a particle diameter at 90 cumulative% in a cumulative distribution (D 90 ) to the average particle diameter (D 50 ), D 90 /D 50 , of the negative electrode active material is 1.3 or smaller.
7. The negative electrode for a lithium ion secondary battery according to claim 5 , wherein a ratio of a particle diameter at 90 cumulative% in a cumulative distribution (D 90 ) to the average particle diameter (D 50 ), D 90 /D 50 , of the fine graphite material is larger than 1.5.
8. The negative electrode for a lithium ion secondary battery according to claim 5 , wherein a ratio of a particle diameter at 90 cumulative % in a cumulative distribution (D 90 ) to the average particle diameter (D 50 ), D 90 /D 50 , of the fine graphite material is 1.65 or larger.
9. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein a specific surface area of the fine graphite material is 45 m 2 /g or smaller.
10. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein the fine graphite material comprises a scale-shaped particle.
11. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein the fine graphite material comprises artificial graphite.
12. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein a content of the fine graphite material based on the negative electrode active material is in a range of 0.1 to 6.0% by mass.
13. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein a content of the conductive aid based on the negative electrode active material is in a range of 0.1 to 3.0% by mass.
14. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein the conductive aid comprises an amorphous carbon particle having an average particle diameter (D 50 ) in a range of 10 to 100 nm, or a nanocarbon material.
15. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein the negative electrode active material comprises a spheroidized active material.
16. The negative electrode for a lithium ion secondary battery according to claim 15 , wherein an average particle roundness of the negative electrode active material is in a range of 0.6 to 1.
17. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein the negative electrode active material comprises a graphite material.
18. The negative electrode for a lithium ion secondary battery according to claim 17 , wherein the graphite material comprises natural graphite or natural graphite covered with amorphous carbon.
19. The negative electrode for a lithium ion secondary battery according to claim 1 , wherein a content of the binder based on the negative electrode active material is in a range of 0.5 to 30% by mass.
20. A lithium ion secondary battery comprising a positive electrode, the negative electrode according to claim 1 , and a non-aqueous electrolytic solution.