Negative electrode active material and lithium ion secondary battery using the same

• US 10,644,347 B2
• Filed: 02/22/2017
• Issued: 05/05/2020
• Est. Priority Date: 02/29/2016
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Kawasaki, Daisuke, Ohtsuka, Takashi, Tamai, Suguru, Yoshida, Noboru, Sudo, Shinya
• Primary Examiner(s): Usyatinsky, Alexander
• Application Number:
  US16/079,676
• Publication Number:
  US 20190051928A1
• Time in Patent Office: 1,168 Days
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/0566 Liquid materials
• CPC Class Codes: H01M 10/058 Construction or manufacture
• CPC Class Codes: H01M 10/0585 of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/364 as mixtures
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: H01M 4/583 Carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 4/622 being polymers
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A negative electrode active material constituting a lithium ion secondary battery having high energy density and excellent cycle characteristics, and a negative electrode and a lithium ion secondary battery comprising the same are provided. The present invention relates to a negative electrode active material comprising graphite particles and crystalline silicon particles, wherein a median diameter of the crystalline silicon particles is 0.7 μm or less, and a weight ratio of the crystalline silicon particles to the total weight of the graphite particles and the crystalline silicon particles is 1 wt % or more and 25 wt % or less.

Claims

1. A negative electrode active material comprising graphite particles and crystalline silicon particles, wherein

a median diameter of the crystalline silicon particles is 0.7 μ

m or less,

a weight ratio of the crystalline silicon particles to the total weight of the graphite particles and the crystalline silicon particles is 10 wt % or more and 25 wt % or less,

a crystallite size of the crystalline silicon particles is 50 nm or more and 200 nm or less, and

X/Y is 2.22/100 or more and 46.67/100 or less, in which X is a median diameter of the crystalline silicon particles and Y is a median diameter of the graphite particles.

2. The negative electrode active material according to claim 1, further comprising silicon oxide.

3. The negative electrode active material according to claim 1, wherein X/Y is 2.22/100 or more and 40/100 or less, in which X is a median diameter of the crystalline silicon particles and Y is a median diameter of the graphite particles.

4. A negative electrode comprising the negative electrode active material according to claim 1.

5. The negative electrode according to claim 4, further comprising a negative electrode binder comprising polyacrylic acid and/or polyimide.

6. The negative electrode according to claim 5, wherein the polyacrylic acid comprises a monomer unit based on an ethylenically unsaturated carboxylic acid and a monomer unit based on an alkali metal salt of an ethylenically unsaturated carboxylic acid and/or a monomer unit based on an aromatic vinyl compound.

7. A lithium ion secondary battery comprising the negative electrode according to claim 4.

8. The negative electrode active material according to claim 1, wherein the crystallite size of the crystalline silicon particles is 70 nm or more and 200 nm or less.

9. The negative electrode active material according to claim 1, wherein X/Y is 3.33/100 or more and 30/100 or less, in which X is a median diameter of the crystalline silicon particles and Y is a median diameter of the graphite particles.

10. The negative electrode active material according to claim 8, wherein X/Y is 3.33/100 or more and 30/100 or less, in which X is a median diameter of the crystalline silicon particles and Y is a median diameter of the graphite particles.

11. The negative electrode according to claim 4, further comprising a negative electrode binder comprising a copolymer of an ethylenically unsaturated carboxylic acid, an alkali metal salt monomer of an ethylenically unsaturated carboxylic acid, styrene, and butadiene.