Negative electrode active material, mixed negative electrode active material, and method for producing negative electrode active material

Patent metadata

Field	Value
Publication number	US-11005095-B2
Application number	US-201716091334-A
Country	US
Kind code	B2
Filing date	Apr 10, 2017
Priority date	May 30, 2016
Publication date	May 11, 2021
Grant date	May 11, 2021

Abstract

A negative electrode active material includes a negative electrode active material particle. The negative electrode active material particle includes a silicon compound particle including a silicon compound (SiO x : 0.5≤x≤1.6). The silicon compound particle includes crystalline Li 2 Si 2 O 5 in at least part of the silicon compound particle. Among peak intensities A derived from Li 2 SiO 3 , B derived from Si, a peak intensity C derived from Li 2 Si 2 O 5 , and D derived from SiO 2 which are obtained from a 29 Si-MAS-NMR spectrum of the silicon compound particle, the peak intensity C is the highest intensity, and the peak intensity A and the peak intensity C satisfy a relationship of the formula A<C/3. Thus, a negative electrode active material stabilizes a slurry prepared when a negative electrode of a secondary battery is prepared, and improves initial charge and discharge and cycle characteristics when used as a negative electrode active material for a secondary battery.

First claim

The invention claimed is:

1. A negative electrode active material comprising
a negative electrode active material particle, wherein
the negative electrode active material particle comprises a silicon compound particle comprising a silicon compound (SiO x : 0.5≤x≤1.6),
the silicon compound particle comprises crystalline Li 2 Si 2 O 5 in at least part of the silicon compound particle,
among a peak intensity A derived from Li 2 SiO 3 , a peak intensity B derived from Si, a peak intensity C derived from Li 2 Si 2 O 5 , and a peak intensity D derived from SiO 2 which are obtained from a 29 Si-MAS-NMR spectrum of the silicon compound particle, the peak intensity C is the highest intensity,
the peak intensity A and the peak intensity C satisfy a relationship of the following formula 1,
A<C/ 3, and  formula 1

in the negative electrode active material, a half-value width (2θ) of a diffraction peak attributable to a Si (111) crystal plane obtained by an X-ray diffraction using Cu-Kα ray is 1.2° or more, and a crystallite's size corresponding to the crystal plane is 7.5 nm or less.

2. The negative electrode active material according to claim 1 , wherein the peak intensity A and the peak intensity C in the 29 Si-MAS-NMR spectrum further satisfy a relationship of the following formula 2,
A≤C/ 5.  formula 2

3. The negative electrode active material according to claim 1 , wherein a peak appears in a region near a chemical shift value of −130 ppm in the 29 Si-MAS-NMR spectrum.

4. The negative electrode active material according to claim 1 , wherein the negative electrode active material particles have a median diameter of 1.0 μm or more and 15 μm or less.

5. The negative electrode active material according to claim 1 , wherein the negative electrode active material particle contains a carbon material at a surface layer portion.

6. The negative electrode active material according to claim 5 , wherein the carbon material to be coated has an average thickness of 5 nm or more and 5000 nm or less.

7. A mixed negative electrode active material comprising:
the negative electrode active material according to claim 1 ; and
a carbon-based active material.

8. The mixed negative electrode active material according to claim 7 , wherein a ratio of the negative electrode active material relative to a total amount of the mixed negative electrode active material is 10% by mass or more.

9. A method for producing a negative electrode active material which comprises a negative electrode active material particle comprising a silicon compound particle, the method comprising the steps of:
making silicon compound particles comprising a silicon compound (SiO x : 0.5≤x≤1.6);
inserting lithium into the silicon compound particles so as to include crystalline Li 2 Si 2 O 5 in at least part of the silicon compound particles to prepare negative electrode active material particles;
selecting, from the negative electrode active material particles, such a negative electrode active material particle that, among a peak intensity A derived from Li 2 SiO 3 , a peak intensity B derived from Si, a peak intensity C derived from Li 2 Si 2 O 5 , and a peak intensity D derived from SiO 2 which are obtained from a 29 Si-MAS-NMR spectrum of the negative electrode active material particle, the peak intensity C is the highest intensity, and the peak intensity A and the peak intensity C satisfy a relationship of the following formula 1 and in the negative electrode active material, a half-value width (2θ) of a diffraction peak attributable to a Si (111) crystal plane obtained by an X-ray diffraction using Cu-Kα ray is 1.2° or more, and a crystallite's size corresponding to the crystal plane is 7.5 nm or less; and
producing a negative electrode active material by using the selected negative electrode active material particle,
A<C/ 3.  formula 1

Assignees

• Shinetsu Chemical Co

Inventors

• Hirose Takakazu
• KAMO Hiromichi

Classifications

• C01B33/113

  Silicon oxides; Hydrates thereof {(preparing monoxide by reduction of siliceous material C01B33/182)} · CPC title

• H01M4/58

  of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates · CPC title

• H01M4/48

  of inorganic oxides or hydroxides · CPC title

• H01M4/38

  of elements or alloys · CPC title

• H01M4/36

  Selection of substances as active materials, active masses, active liquids · CPC title