Negative electrode material for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery using the same
View Patent ↗A mixed carbon material is useful for an electrode of a nonaqueous secondary battery. The material has two component materials: carbon material A and carbon material B. Both materials have high capacity and rapid charge-discharge characteristics. Carbon material A, a multilayer-structure material containing an amorphous carbon covering the surface of a graphitic particle, has particularly excellent charging-discharging properties. Carbon material B has particularly excellent electrical conductivity properties. A battery with an electrode having the mixed carbon material can have both rapid charge-discharge characteristics and high cycle characteristics.
1. A negative electrode material for nonaqueous electrolyte secondary battery, comprising the following carbon material A and carbon material B:
Carbon material A
a multilayer-structure carbon material containing a graphitic particle and an amorphous carbon covering the surface of the graphitic particle, wherein the carbon material A has an interplanar spacing (d002) of 002 planes by the wide-angle X-ray diffraction method of 3.37 Å or less, an Lc of 900 Å or more, a tap density of 0.8 g/cm 3 or more, and a Raman R value that is a ratio of the peak intensity near 1,360 cm −1 to the peak intensity near 1,580 cm −1 in the argon ion laser Raman spectrum of from 0.25 to 0.6,
Carbon material B
wherein the carbon material B has an interplanar spacing (d002) of 002 planes by the wide-angle X-ray diffraction method of 3.37 Å or less, an Lc of 900 Å or more, a tap density of 0.8 g/cm 3 or more, and a Raman R value that is a ratio of the peak intensity near 1,360 cm −1 to the peak intensity near 1,580 cm −1 in the argon ion laser Raman spectrum of from 0.11 to 0.2, and wherein the carbon material (B) is a multilayer-structure carbon material containing a spheroidized graphitic particle and a graphitic carbon covering the surface of the spheroidized graphitic particle,
wherein the ratio in the average particle diameter between the carbon material A and the carbon material B (average particle diameter of carbon material A/average particle diameter of carbon material B) is from 0.7 to 1.3.
2. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the ratio of the carbon material B is from 30 to 70 wt % based on the total amount of the carbon material A and the carbon material B.
3. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the graphitic particle in the carbon material A has an interplanar spacing (d002) of 002 planes by the wide-angle X-ray diffraction method of 3.37 Å or less, an Lc of 900 Å or more, a tap density of 0.8 g/cm 3 or more, and a Raman R value that is a ratio of the peak intensity near 1,360 cm −1 to the peak intensity near 1,580 cm −1 in the argon ion laser Raman spectrum of from 0.2 to 0.5.
4. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the spheroidized graphitic particle has an interplanar spacing (d002) of 002 planes by the wide-angle X-ray diffraction method of 3.37 Å or less, an Lc of 900 Å or more, a tap density of 0.8 g/cm 3 or more, and a Raman R value that is a ratio of the peak intensity near 1,360 cm −1 to the peak intensity near 1,580 cm −1 in the argon ion laser Raman spectrum of from 0.2 to 0.5.
5. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the specific surface area of the carbon material A is from 0.5 to 8 m 2 /g.
6. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the average degree of circularity of the graphitic particle used for the carbon material A as determined by a flow-type particle analyzer is 0.88 or more.
7. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the average degree of circularity of a spheroidized graphitic particle in the carbon material B as determined by a flow-type particle analyzer is 0.88 or more.
8. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the pore volumes in the range of 10 to 100,000 nm of the carbon material A and the carbon material B as measured by the mercury intrusion method, are 0.4 ml/g or more.
9. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the average particle diameter of the carbon material A is from 2 to 30 μm.
10. A negative electrode for nonaqueous electrolyte secondary battery, comprising: a negative electrode layer containing the negative electrode material for nonaqueous electrolyte secondary battery claimed in claim 1 and a binder resin; and a current collector.
11. A nonaqueous electrolyte secondary battery comprising the negative electrode claimed in claim 10 , a positive electrode capable of storing/releasing lithium ion, and a nonaqueous electrolytic solution.
12. The negative electrode material as claimed in claim 1 , wherein the carbon material B is present in an amount of from 10 to 90 wt % based on the total weight of the carbon material A and the carbon material B.
13. The negative electrode material as claimed in claim 1 , wherein the carbon material B is present in an amount of from 20 to 80 wt % based on the total weight of the carbon material A and the carbon material B.
14. The negative electrode material as claimed in claim 1 , wherein the carbon material B is present in an amount of from 30 to 70 wt % based on the total weight of the carbon material A and the carbon material B.
15. The negative electrode material as claimed in claim 1 , wherein the Raman R value of the carbon material B is from 0.11 to 0.13.
16. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the ratio of carbon material (B) is from 20 to 80 wt % based on the total amount of the carbon material (A) and the carbon material (B).
17. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the ratio in the average particle diameter between the carbon material (A) and the carbon material (B) is from 0.8 to 1.2.
18. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the ratio of the carbon material (B) is from 30 to 50 wt % based on the total amount of the carbon material (A) and the carbon material (B).
19. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the ratio of the carbon material (B) is from 50 to 70 wt % based on the total amount of the carbon material (A) and the carbon material (B).
20. The negative electrode material for nonaqueous electrolyte secondary battery as claimed in claim 1 , wherein the ratio in the average particle diameter between the carbon material (A) and the carbon material (B) is from 0.7 to 0.89.