Negative electrode active material for non-aqueous electrolyte secondary battery, negative electrode for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery, and method of producing negative electrode active material particles

Patent metadata

Field	Value
Publication number	US-10535872-B2
Application number	US-201615575183-A
Country	US
Kind code	B2
Filing date	Apr 21, 2016
Priority date	Jun 2, 2015
Publication date	Jan 14, 2020
Grant date	Jan 14, 2020

Abstract

A negative electrode active material that includes negative electrode active material particles that contain a silicon compound that contains a Li compound. The silicon compound is at least partially coated with a carbon coating, and the negative electrode active material particles are coated with a coating composed of at least one of a compound having a boron-fluorine bond and a compound having a phosphorous-fluorine bond on at least a part of the surface of either or both of the silicon compound and the carbon coating. The negative electrode active material particles contain a boron or a phosphorous element in a range of 10 to 10000 ppm by mass with respect to the total amount of negative electrode active material particles. These features can provide for a negative electrode active material that can increase battery capacity and improve cycle performance in a non-aqueous electrolyte secondary battery.

First claim

The invention claimed is:

1. A negative electrode active material for a non-aqueous electrolyte secondary battery, comprising:
negative electrode active material particles that contain a silicon compound containing a Li compound;
wherein:
the silicon compound is represented by formula SiO x , where 0.5≤x≤1.6,
the silicon compound is at least partially coated with a first coating that is a carbon coating,
the negative electrode active material particles are coated with a second coating that is composed of at least one compound selected from the group consisting of a compound having a boron-fluorine bond and a compound having a phosphorous-fluorine bond, where the second coating coats at least a part of a surface of the silicon compound, at least a part of a surface of the first coating, or both,
the negative electrode active material particles contain:
(i) a boron element or a phosphorous element in a range of 10 ppm by mass to 10000 ppm by mass with respect to a total amount of the negative electrode active material particles, and
(ii) at least one selected from the group consisting of sodium, potassium, magnesium, calcium, and a salt thereof, where:
(a) the sodium element or the potassium element is present in a range of 10 ppm by mass to 200 ppm by mass on an individual basis with respect to the total amount of the negative electrode active material particles, and/or
(b) the magnesium element or the calcium element is present in a range of 5 ppm by mass to 50 ppm by mass with respect to the total amount of the negative electrode active material particles.

2. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the negative electrode active material particles contain the boron element or the phosphorous element in a range of 500 ppm by mass to 5000 ppm by mass with respect to the total amount of the negative electrode active material particles.

3. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein one or more of the following: (i) the surface of the silicon compound, (ii) the surface of the first coating, and (iii) the surface of second coating contains aluminum oxide, and an amount of an aluminum element is in a range of 50 ppm to 500 ppm with respect to the total amount of the negative electrode active material particles.

4. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the negative electrode active material particles further contain at least one selected from the group consisting of chromium, iron, and copper in a range of 10 ppm by mass to 500 ppm by mass with respect to the total amount of the negative electrode active material particles.

5. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the negative electrode active material particles further contain an acid and a Li salt thereof, and the acid and the Li salt thereof are on an outer periphery of the carbon coating.

6. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the silicon compound contains in its interior at least one Li compound selected from the group consisting of Li 2 SiO 3 , Li 6 Si 2 O 7 , and Li 4 SiO 4 .

7. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the negative electrode active material particles are produced by a process including an electrochemical method.

8. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the carbon coating exhibits scattering peaks at 1330 cm −1 and 1580 cm −1 in Raman spectrometry and satisfies 0.7<I 1330 /I 1580 <2.0 where I 1330 /I 1580 is a ratio of an intensity of the scattering peak at 1330 cm −1 to that at 1580 cm −1 .

9. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein a content of the carbon coating is 5.0% by mass or more and 20% by mass or less with respect to a mass of the negative electrode active material particles.

10. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the silicon compound exhibits a diffraction peak having a half width (2θ) of 1.2° or more, the diffraction peak being attributable to a Si (111) crystal face and obtained by X-ray diffraction, and a crystallite size attributable to the crystal face is 7.5 nm or less.

11. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the silicon compound has a median size D 50 of 0.5 μm or more and 20 μm or less.

12. A negative electrode for a non-aqueous electrolyte secondary battery comprising a negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 and a carbon-based active material.

13. The negative electrode for a non-aqueous electrolyte secondary battery according to claim 12 , wherein a ratio of the negative electrode active material is 5% by mass or more with respect to a total amount of the carbon-based active material and the negative electrode active material.

14. A non-aqueous electrolyte secondary battery comprising a negative electrode for a non-aqueous electrolyte secondary battery according to claim 12 .

Assignees

• Shinetsu Chemical Co

Inventors

• Matsuno Takumi
• KAMO Hiromichi
• Hirose Takakazu
• Yoshikawa Hiroki

Classifications

• H01M4/587

  for inserting or intercalating light metals · CPC title

• C01B32/05

  Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30 · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/483

  for non-aqueous cells (H01M4/485 takes precedence) · CPC title

• H01M4/583

  Carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title