Negative electrode material 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 includes a silicon oxide and having a diffraction peak attributable to Si (111) in an X-ray diffraction spectrum, in which a size of a silicon crystallite calculated from the diffraction peak is from 2.0 nm to 8.0 nm.
1. A lithium ion secondary battery, comprising:
a positive electrode;
a negative electrode for a lithium ion secondary battery comprising a current collector, and a negative electrode material layer provided on the current collector, the negative electrode material layer comprising a negative electrode material (SiOx-C) comprising:
a silicon oxide represented by a formula SiOx (x is 0<+≤2) having silicon crystallite present and having a diffraction peak attributable to Si (111) in an X-ray diffraction spectrum,
wherein a size of silicon crystallite calculated from the diffraction peak is from 2.0 nm to 8.0 nm,
wherein the silicon oxide further comprises carbon on a part of a surface thereof or the entire surface thereof,
wherein the carbon has an R value in a Raman spectrum of from 0.5 to 1.5, and
wherein a content ratio of the carbon is 0.5% by mass or more and less than 5.0% by mass; and
an electrolyte,
wherein the negative electrode material layer further comprises a carbonaceous negative electrode material (C), and a ratio of the negative electrode material (SiOx-C) to the carbonaceous negative electrode material (C) is from 1:99 to 10:90 in terms of mass.
2. The lithium ion secondary battery according to claim 1 , wherein the carbon is provided on a part of the surface of the silicon oxide.
3. The lithium ion secondary battery according to claim 1 , wherein the carbon is provided on the entire surface of the silicon oxide.
4. The lithium ion secondary battery according to claim 1 , wherein the R value of the carbon in the Raman spectrum is from 0.7 to 1.3.
5. The lithium ion secondary battery according to claim 1 , wherein the R value of the carbon in the Raman spectrum is from 0.8 to 1.2.
6. The lithium ion secondary battery according to claim 1 , wherein the R value of the carbon in the Raman spectrum is from 0.7 to 1.5.
7. The lithium ion secondary battery according to claim 1 , wherein the R value of the carbon in the Raman spectrum is from 0.8 to 1.5.
8. The lithium ion secondary battery according to claim 1 , wherein the R value of the carbon in the Raman spectrum is from 0.5 to 1.3.
9. The lithium ion secondary battery according to claim 1 , wherein the R value of the carbon in the Raman spectrum is from 0.5 to 1.2.
10. The lithium ion secondary battery according to claim 1 , wherein a size of a silicon crystallite calculated from the diffraction peak is from 2.0 nm to 6.0 nm.
11. The lithium ion secondary battery according to claim 1 , wherein the content ratio of the carbon is 0.5% by mass to 4.5% by mass.
12. The lithium ion secondary battery according to claim 1 , wherein a size of a silicon crystallite calculated from the diffraction peak is from 2.0 nm to 5.0 nm.
13. The lithium ion secondary battery according to claim 1 , wherein a size of a silicon crystallite calculated from the diffraction peak is from 3.0 nm to 8.0 nm.
14. The lithium ion secondary battery according to claim 1 , wherein a size of a silicon crystallite calculated from the diffraction peak is from 4.0 nm to 8.0 nm.