Negative electrode active material, raw material for a negative electrode active material, negative electrode, lithium ion secondary battery, method for producing a negative electrode active material, and method for producing a lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-2016233484-A1
Application number	US-201414910201-A
Country	US
Kind code	A1
Filing date	May 30, 2014
Priority date	Aug 21, 2013
Publication date	Aug 11, 2016
Grant date	—

Abstract

A negative electrode active material including: a particle of negative electrode active material containing silicon-based material of SiO x (0.5≦x≦1.6); wherein the intensity A of a peak in a Si-region given in the chemical shift region of from −50 to −95 ppm and the intensity B of a peak in a SiO 2 -region given in the chemical shift region of from −96 to −150 ppm in a 29 Si-MAS-NMR spectrum of the silicon-based material satisfy a relationship that A/B≧0.8. This provides a negative electrode active material which can increase a battery capacity, and can improve cycle characteristics and initial charge/discharge characteristics when used as a negative electrode active material for a lithium ion secondary battery.

First claim

1 . A negative electrode active material comprising:
a particle of negative electrode active material containing silicon-based material consisting of SiO x (0.5≦x≦1.6); wherein the intensity A of a peak in a Si-region given in the chemical shift region of from −50 to −95 ppm and the intensity B of a peak in a SiO 2 -region given in the chemical shift region of from −96 to −150 ppm in a 29 Si-MAS-NMR spectrum of the silicon-based material satisfy a relationship that A/B≧0.8.

2 . The negative electrode active material according to claim 1 , wherein the particle of negative electrode active material has a peak given in the chemical shift region of from −70 to −85 ppm in a 29 Si-MAS-NMR spectrum.

3 . The negative electrode active material according to claim 1 , wherein the particle of negative electrode active material has at least two peaks given in the chemical shift region of from −50 to −95 ppm in a 29 Si-MAS-NMR spectrum.

4 . The negative electrode active material according to claim 1 , wherein the particle of negative electrode active material has at least one peak corresponding to any one or more of Li 2 SiO 3 and Li 4 SiO 4 in a region given in the chemical shift region of from −50 to −95 ppm in a 29 Si-MAS-NMR spectrum.

5 . The negative electrode active material according to claim 1 , wherein the particle of negative electrode active material has a peak corresponding to metal Si in a region given in the chemical shift region of from −50 to −95 ppm in a 29 Si-MAS-NMR spectrum.

6 . The negative electrode active material according to claim 1 , wherein the particle of negative electrode active material contains any one or more of Li 2 SiO 3 , Li 4 SiO 4 , Li 2 O, and Li 2 CO 3 .

7 . The negative electrode active material according to claim 6 , wherein the particle of negative electrode active material contains any two or more of Li 2 SiO 3 , Li 4 SiO 4 , Li 2 O, and Li 2 CO 3 .

8 . The negative electrode active material according to claim 6 , wherein the Li 2 SiO 3 has a diffraction peak near 38.2680° in which the full width at half maximum (2θ) is 0.75° or more in an X-ray diffraction.

9 . The negative electrode active material according to claim 6 , wherein the Li 4 SiO 4 has a diffraction peak near 23.9661° in which the full width at half maximum (2θ) is 0.2° or more in an X-ray diffraction.

10 . The negative electrode active material according to claim 6 , wherein the Li 2 SiO 3 and the Li 4 SiO 4 are amorphous.

11 . The negative electrode active material according to claim 1 , wherein the particle of negative electrode active material contains a fluorine compound in the form of an island, a film, or an unevenness on at least a part of its surface.

12 . The negative electrode active material according to claim 11 , wherein the fluorine compound is lithium fluoride or a decomposition product of LiPF 6 .

13 . The negative electrode active material according to claim 1 , wherein the negative electrode active material has a diffraction peak attributable to (111) crystal face in which the full width at half maximum (2θ) is 1.2° or more in an X-ray diffraction, and the size of the crystallite corresponding to the crystal face is 7.5 nm or less.

14 . The negative electrode active material according to claim 1 , wherein the particle of negative electrode active material has a median diameter of 0.5 μm or more and 20 μm or less.

15 . The negative electrode active material according to claim 1 , wherein the particle of negative electrode active material has carbon material on its surface.

16 . The negative electrode active material according to claim 15 , wherein the average thickness of the coating carbon material is 1 nm or more and 5000 nm or less.

17 . The negative electrode active material according to claim 1 , wherein the particle of negative electrode active material has SiO x , carbon, and a fluorine compound or has SiO x and a fluorine compound at least partially.

18 . The negative electrode active material according to claim 11 , wherein the mean coverage of the coating layer consisting of the fluorine compound is 30% or more.

19 . The negative electrode active material according to claim 15 , wherein the mean coverage of the coating layer consisting of the carbon material is 30% or more.

20 . A raw material for a negative electrode active material comprising the negative electrode active material according to claim 1 ; and a carbon material.

21 . A negative electrode comprising:
a negative electrode active material layer formed by the raw material for a negative electrode active material according to claim 20 ; and a negative electrode current collector, wherein the negative electrode active material layer is formed on the negative electrode current collector; and the negative electrode current collector contains carbon and sulfur, and each content is 100 ppm or less.

22 . A lithium ion secondary battery, wherein the lithium ion secondary battery uses a negative electrode containing the negative electrode active material according to claim 1 .

23 . A method for producing a negative electrode active material containing a particle of negative electrode active material which contains silicon-based material consisting of SiO x , comprising:
selecting and then using a silicon-based material wherein the x is 0.5 or more and 1.6 or less and the intensity A of a peak in a Si-region given in the chemical shift region of from −50 to −95 ppm and the intensity B of a peak in a SiO 2 -region given in the chemical shift region of from −96 to −150 ppm in a 29 Si-MAS-NMR spectrum satisfy a relationship that A/B≧0.8.

24 . A method for producing a lithium ion secondary battery, comprising:
preparing a negative electrode by using a negative electrode active material made by the method for producing a negative electrode active material according to claim 23 ; and producing a lithium ion secondary battery by using the prepared negative electrode.

Assignees

• Shinetsu Chemical Co

Inventors

• Hirose Takakazu
• KAMO Hiromichi
• Yoshikawa Hiroki

Classifications

• H01M2220/30

  Batteries in portable systems, e.g. mobile phone, laptop · CPC title

• H01M4/364

  as mixtures · CPC title

• H01M4/1391

  of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• H01M4/366

  as layered products · CPC title

• H01M4/134

  Electrodes based on metals, Si or alloys · CPC title