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 including carbon over a part or a whole of a surface of an oxide of silicon, in which the content of the carbon is from 0.5 mass-% to less than 5 mass-%.
1. A negative electrode material for a lithium ion secondary battery, comprising:
a negative electrode material (SiOx-C) that includes an oxide of silicon and silicon crystallites, and carbon over a part or a whole of a surface of the oxide of silicon; and
a carbonaceous negative electrode material that includes at least one selected from the group consisting of natural graphite, artificial graphite, and amorphous carbon, wherein:
a content of the carbon with respect to the whole negative electrode material (SiOx-C) is from 0.5 mass % to 4.5 mass %; and
a crystallite size of the silicon crystallites that are included in the negative electrode material (SiOx-C) is 3 nm or more and 6 nm or less;
the carbon that is included in the negative electrode material (SiOx-C) comprises low crystallinity carbon, and has an R value, defined as a ratio Id/Ig of a peak Id in a profile obtained by laser Raman spectrometry with an excitation wavelength of 532 nm observed between 1300 cm −1 and 1400 cm −1 to a peak Ig in a profile obtained by laser Raman spectrometry with an excitation wavelength of 532 nm observed between 1530 cm −1 and 1630 cm −1 , of from 0.7 to 1.3;
the oxide of silicon that is included in the negative electrode material (SiOx-C) is represented by a formula SiOx (x is 0<x≤2); and
a ratio of the negative electrode material (SiOx-C) with respect to the carbonaceous negative electrode material (C) is from 0.1:99.9 to 20:80 in terms of mass.
2. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein the crystallite size of the silicon crystallites is from 2 nm to 8 nm.
3. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein the crystallite size of the silicon crystallites is from 3 nm to 6 nm.
4. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein the carbon comprises low crystallinity carbon, and has an R value, defined as a ratio Id/Ig of a peak Id in a profile obtained by laser Raman spectrometry with an excitation wavelength of 532 nm observed between 1300 cm −1 and 1400 cm −1 to a peak Ig in a profile obtained by laser Raman spectrometry with an excitation wavelength of 532 nm observed between 1530 cm −1 and 1630 cm −1 , of 0.5 or more.
5. The negative electrode material for a lithium ion secondary battery according to claim 4 , wherein the carbon has an R value of from 0.7 to 1.3.
6. The negative electrode material for a lithium ion secondary battery according to claim 4 , wherein the carbon has an R value of from 0.8 to 1.2.
7. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein a diffraction peak assignable to Si (111) is observed when the negative electrode material (SiOx-C) is subjected to a powder X-ray diffraction (XRD) analysis.
8. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein the oxide of silicon is represented by a formula SiOx (x is 0<x≤2).
9. The negative electrode material for a lithium ion secondary battery according to claim 1 , further comprising a carbonaceous negative electrode material (C) that includes at least one selected from the group consisting of natural graphite, artificial graphite, and amorphous carbon.
10. The negative electrode material for a lithium ion secondary battery according to claim 9 , wherein a ratio of the negative electrode material (SiOx-C) with respect to the carbonaceous negative electrode material (C) is from 0.1:99.9 to 20:80 in terms of mass.
11. The negative electrode material for a lithium ion secondary battery according to claim 9 , wherein the crystallite size of the silicon crystallites that is included in the negative electrode material (SiOx-C) is from 2 nm to 8 nm.
12. The negative electrode material for a lithium ion secondary battery according to claim 9 , wherein the crystallite size of the silicon crystallites that is included in the negative electrode material (SiOx-C) is from 3 nm to 6 nm.
13. The negative electrode material for a lithium ion secondary battery according to claim 9 , wherein the carbon that is included in the negative electrode material (SiOx-C) comprises low crystallinity carbon, and has an R value, defined as a ratio Id/Ig of a peak Id in a profile obtained by laser Raman spectrometry with an excitation wavelength of 532 nm observed between 1300 cm −1 and 1400 cm −1 to a peak Ig in a profile obtained by laser Raman spectrometry with an excitation wavelength of 532 nm observed between 1530 cm −1 and 1630 cm −1 , of 0.5 or more.
14. The negative electrode material for a lithium ion secondary battery according to claim 13 , wherein the carbon that is included in the negative electrode material (SiOx-C) has an R value of from 0.7 to 1.3.
15. The negative electrode material for a lithium ion secondary battery according to claim 9 , wherein the oxide of silicon that is included in the negative electrode material (SiOx-C) is represented by a formula SiOx (x is 0<x≤2).
16. A negative electrode for a lithium ion secondary battery, comprising:
a current collector; and
a negative electrode material layer provided on the current collector and comprising the negative electrode material according to claim 1 .
17. A lithium ion secondary battery, comprising:
a positive electrode;
the negative electrode for a lithium ion secondary battery according to claim 16 ; and
an electrolyte.
18. A negative electrode material for a lithium ion secondary battery, comprising:
a negative electrode material (SiOx-C) that includes an oxide of silicon and silicon crystallites, and carbon over a part or a whole of a surface of the oxide of silicon and
a carbonaceous negative electrode material that includes at least one selected from the group consisting of natural graphite, artificial graphite, and amorphous carbon, wherein:
a content of the carbon with respect to the whole negative electrode material (SiOx-C) is from 0.5 mass % to 4.5 mass %;
a crystallite size of the silicon crystallites that are included in the negative electrode material (SiOx-C) is 3 nm or more and 6 nm or less;
the carbon that is included in the negative electrode material (SiOx-C) comprises low crystallinity carbon, and has an R value, defined as a ratio Id/Ig of a peak Id in a profile obtained by laser Raman spectrometry with an excitation wavelength of 532 nm observed between 1300 cm −1 and 1400 cm −1 to a peak Ig in a profile obtained by laser Raman spectrometry with an excitation wavelength of 532 nm observed between 1530 cm −1 and 1630 cm −1 , of from 0.7 to 1.3;
the oxide of silicon that is included in the negative electrode material (SiOx-C) is represented by a formula SiOx (x is 0<x≤2); and
a ratio of the negative electrode material (SiOx-C) with respect to the carbonaceous negative electrode material (C) is from 0.1:99.9 to 20:80 in terms of mass.