Cathode active material for secondary battery and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-11588152-B2
Application number	US-201716326873-A
Country	US
Kind code	B2
Filing date	Aug 23, 2017
Priority date	Aug 23, 2016
Publication date	Feb 21, 2023
Grant date	Feb 21, 2023

Abstract

The present invention relates to a cathode active material for a secondary battery and a manufacturing method thereof. A cathode active material, according to one embodiment of the present invention, comprises silicon-based primary particles, and a particle size distribution of the silicon-based primary particles is D10≥50 nm and D90≤150 nm. The cathode active material suppresses or reduces tensile hoop stress generated in lithiated silicon particles during a charging of a battery to thus suppress a crack due to a volume expansion of the silicon particles and/or an irreversible reaction caused by the crack, such that the lifetime and capacity of the battery can be improved.

First claim

The invention claimed is:

1. A negative electrode active material for a secondary battery,
wherein the negative electrode active material comprises silicon-based primary particles,
a particle size distribution of the silicon-based primary particles is 50 nm≤D10<80 nm, 80 nm≤D50 (median particle diameter)≤100 nm, and 105 nm<D90≤150 nm,
the particle size distribution width (D90−D10)/D50 of the silicon-based primary particles is 1.0 or less,
circularity of the silicon-based primary particles is in a range of 0.6 to 0.8, wherein the circularity is defined as:

circularity
=

2
⁢

π
⁢
A

P

where A is a projected area of the two-dimensionally projected silicon-based primary particles, and P is a perimeter of the two-dimensionally projected silicon-based primary particles, and
the silicon-based primary particles comprise a silicon particle core and a chemical silicon oxide layer formed by an oxidizing solvent on the core.

2. The negative electrode active material for a secondary battery as claimed in claim 1 , wherein in the silicon-based primary particles the oxygen content relative to the total weight of the silicon particle core and the silicon oxide layer is limited to the range of 9 wt % to 20 wt %.

3. The negative electrode active material for a secondary battery as claimed in claim 2 , wherein in the silicon-based primary particles the oxygen content relative to the total weight of the silicon particle core and the silicon oxide layer is limited to the range of 10 wt % to 17 wt %.

4. The negative electrode active material for a secondary battery as claimed in claim 1 , wherein the purity of the silicon-based primary particles is 99% or greater.

5. The negative electrode active material for a secondary battery as claimed in claim 1 , wherein the particle distribution width of the silicon-based primary particles is 0.9 or less.

6. The negative electrode active material for a secondary battery as claimed in claim 1 , wherein the D100 particle size of the silicon-based primary particles is less than 250 nm.

7. The negative electrode active material of claim 1 , wherein 130 nm≤D90≤150 nm.

8. A method for preparing a negative electrode active material for a secondary battery, the method comprising:
a step of providing silicon powder;
a step of providing a dispersion mixture in which the silicon powder is dispersed in an oxidizing solvent;
a step of applying mechanical stress energy to the silicon powder of the dispersion mixture to form finely granulated silicon particles comprising a silicon particle core and a chemical silicon oxide layer formed by the oxidizing solvent on the core, wherein a particle size distribution of the finely granulated silicon particles is 50 nm≤D10<80 nm, 80 nm≤D50 (median particle diameter)≤100 nm, and 105 nm<D90≤150 nm and the particle size distribution width (D90−D10)/D50 is 1.0 or less, and wherein circularity of the finely granulated silicon particles is in a range of 0.6 to 0.8, wherein the circularity is defined as:

circularity
=

2
⁢

π
⁢
A

P

where A is a projected area of the two-dimensionally projected silicon particles, and P is a perimeter of the two-dimensionally projected silicon particles; and
a step of drying the resulting product comprising the finely granulated silicon particles to obtain silicon-based particles.

9. The method as claimed in claim 8 , wherein the oxidizing solvent comprises water, deionized water, an alcoholic solvent, or a mixture of two or more thereof.

10. The method as claimed in claim 9 , wherein the alcoholic solvent comprises any solvent selected from the group consisting of ethyl alcohol, methyl alcohol, glycerol, propylene glycol, isopropyl alcohol, isobutyl alcohol, polyvinyl alcohol, cyclohexanol, octyl alcohol, decanol, hexadecanol, ethylene glycol, 1,2-octanediol, 1,2-dodecanediol, and 1,2-hexadecanediol, and a mixture thereof.

11. The method as claimed in claim 10 , wherein the D100 particle size of the finely granulated silicon particles is less than 250 nm.

12. The method as claimed in claim 8 , wherein the application of mechanical stress energy is achieved by a mill pulverization process using a composition of abrasive particles along with the oxidizing solvent.

13. The method of claim 8 , wherein before the step of drying the resulting product, an aging step is performed by dispersing and stirring the resulting product into an oxidizing solvent or a mixed solution thereof.

14. The method of claim 8 , wherein 130 nm≤D90≤150 nm.

Assignees

• Nexeon Ltd

Inventors

• Park Seung Chul
• Song Eui Joon
• Cho Young Tai
• Park Jee Hye

Classifications

• H01M4/386 Primary

  Silicon or alloys based on silicon · CPC title

• C01B33/021

  Preparation (chemical coating from the vapour phase C23C16/00) · CPC title

• Y02P70/50

  Manufacturing or production processes characterised by the final manufactured product · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M4/1395

  of electrodes based on metals, Si or alloys · CPC title