Negative electrode active material and lithium secondary battery comprising same

• US 10,586,976 B2
• Filed: 04/22/2015
• Issued: 03/10/2020
• Est. Priority Date: 04/22/2014
• Status: Active Grant

• Current Assignee: Nexeon Limited
• Original Assignee: Nexeon Limited
• Inventors: Cho, Young Tai, Park, Seung Chul, Park, Seon, Seo, Hee Young, Park, Jee Hye, Lee, Yong Eui, Kim, Chul Hwan
• Primary Examiner(s): Jones, Robert S
• Assistant Examiner(s): Lynch, Victoria H
• Application Number:
  US15/305,763
• Publication Number:
  US 20170047580A1
• Time in Patent Office: 1,784 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 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 2220/10 Batteries in stationary systems, e.g. emergency power source in plant
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 2220/30 Batteries in portable systems, e.g. mobile phone, laptop
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/38 of elements or alloys
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: H01M 4/626 Metals
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Provided is a negative active material and a lithium secondary battery including the negative active material. The negative active material for a secondary battery includes silicon particles, wherein circularities of the particles are determined by equation 1 below, and the circularities are 0.5 or greater and 0.9 or less,
Circularity=2(pi×A)^1/2/P  [Equation 1]

• • where A denotes a projected area of the silicon particle that is two-dimensionally projected, and P denotes a circumferential length of the silicon particle that is two-dimensionally projected.

Claims

1. A negative active material for a secondary battery, the negative active material comprising silicon particles,

wherein an average diameter of the silicon particles is in a range from 30 nm to 300 nm, and

wherein circularities of the silicon particles are determined by Equation 1 below, and the circularities are 0.5 or greater and 0.9 or less,

Circularity=2(pi×

A)^1/2/P 

 

[Equation 1]

where A denotes a projected area of a silicon particle that is two-dimensionally projected, and P denotes a circumferential length of the silicon particle that is two-dimensionally projected.

2. The negative active material of claim 1, wherein the silicon particles comprise solid particles.

3. The negative active material of claim 1, wherein the circularities of the silicon particles are 0.6 or greater and 0.8 or less.

4. The negative active material of claim 1, wherein an area of a (110) surface of each of the silicon particles is greater than an area of a (100) surface and an area of a (111) surface.

5. The negative active material of claim 1, wherein the silicon particles comprise a silicon oxide layer formed as a shell on the silicon particles.

6. The negative active material of claim 5, wherein the silicon particles comprise a silicon carbide layer formed as a shell on the silicon oxide layer.

7. The negative active material of claim 5, wherein a thickness of the silicon oxide layer is in a range of 0.5 nm to 20 nm.

8. The negative active material of claim 5, wherein the silicon oxide layer is chemical silicon oxide that is artificially grown using a solvent comprising oxygen.

9. The negative active material of claim 8, wherein the solvent comprising oxygen is alcohol, distilled water, or a peroxide compound.

10. The negative active material of claim 1, further comprising a conductive layer formed on the silicon particles.

11. The negative active material of claim 10, wherein the conductive layer comprises an amorphous carbon layer or conductive metal oxide particles.

12. The negative active material of claim 1, wherein the silicon particles have a purity of 99% or greater.

13. A lithium secondary battery comprising the negative active material of claim 1.

14. The negative active material of claim 1, wherein the silicon particles have irregular shapes.

15. The negative active material of claim 1, wherein a dominant external surface of each of the silicon particles is a {110} surface.