Positive electrode active material particle including core including lithium cobalt oxide and shell including lithium cobalt phosphate and preparation method thereof

Patent metadata

Field	Value
Publication number	US-11056682-B2
Application number	US-201716308667-A
Country	US
Kind code	B2
Filing date	Jul 27, 2017
Priority date	Nov 22, 2016
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

Provided is a positive electrode active material particle including a core that includes lithium cobalt oxide represented by the following Chemical Formula 1; and a shell that is located on the surface of the core and includes lithium cobalt phosphate represented by the following Chemical Formula 2, wherein the shell has a tetrahedral phase:

Li a Co (1-x) M x O 2-y A y   (1)

wherein M is at least one of Ti, Mg, Zn, Si, Al, Zr, V, Mn, Nb, or Ni, A is oxygen-substitutional halogen, and 0.95≤a≤1.05, 0≤x≤0.2, 0≤y≤0.2, and 0≤x+y≤0.2,

Li b CoPO 4   (2)

wherein 0≤b≤1.

First claim

The invention claimed is:

1. A positive electrode active material particle comprising a core that includes lithium cobalt oxide represented by the following Chemical Formula 1; and
a tetrahedral phase shell that is located on a surface of the core and includes lithium cobalt phosphate represented by the following Chemical Formula 2:
Li a Co (1-x) M x O 2-y A y   (1)

wherein M is at least one of Ti, Mg, Zn, Si, Al, Zr, V, Mn, Nb, or Ni, A is oxygen-substitutional halogen, and 0.95≤a≤1.05, 0≤x≤0.2, 0≤y≤0.2, and 0≤x+y≤0.2,
Li b CoPO 4   (2)

wherein 0≤b≤1.

2. The positive electrode active material particle of claim 1 , wherein a weight of the tetrahedral phase shell relative to a weight of the core is 0.1% by weight to 3.0% by weight.

3. The positive electrode active material particle of claim 1 , wherein an average particle diameter (D50) of the lithium cobalt oxide is 5 micrometer to 25 micrometer.

4. The positive electrode active material particle of claim 1 , wherein a thickness of the tetrahedral phase shell is 1 Å to 1 μm.

5. The positive electrode active material particle of claim 1 , wherein the tetrahedral phase shell is formed on the area of 50% to 100% with respect to the surface area of the core.

6. The positive electrode active material particle of claim 1 , wherein the lithium cobalt phosphate of the tetrahedral phase shell undergoes a phase transfer to an olivine phase at a temperature of 220° C. or higher.

7. The positive electrode active material particle of claim 6 , wherein a tetrahedral phase of the lithium cobalt phosphate has higher ionic conductivity than the olivine phase.

8. The positive electrode active material particle of claim 1 , wherein due to an electrochemical reaction by Co 2+ /Co 3+ redox coupling at a potential of 4.9 V or higher, the lithium cobalt phosphate of the tetrahedral phase shell has a property of inhibiting an oxygen release phenomenon which is caused by lithium deintercalation in the lithium cobalt oxide of the core during overcharging.

9. The positive electrode active material particle of claim 1 , wherein the surface of the tetrahedral phase shell is coated with Al 2 O 3 .

10. The positive electrode active material particle of claim 9 , wherein a thickness of the Al 2 O 3 coating is 5 nm to 100 nm.

11. A method of preparing the positive electrode active material particle of claim 1 , the method comprising:
preparing a mixed solution in which a cobalt source, a phosphorus source, and a lithium source are mixed;
adding lithium cobalt oxide in a particle state to the mixed solution, followed by mixing to form a solution; and
performing a hydrothermal reaction of the solution.

12. The method of claim 11 , wherein the cobalt source is cobalt oxide or cobalt nitride.

13. The method of claim 11 , wherein the phosphorus source is phosphoric acid or a salt thereof.

14. The method of claim 11 , wherein the lithium source is lithium hydroxide or lithium carbonate.

15. The method of claim 11 , wherein the lithium cobalt oxide is mixed so that a weight ratio of the lithium cobalt phosphate to the lithium cobalt oxide in the positive electrode active material particle prepared by the hydrothermal reaction becomes 0.1% by weight to 3.0% by weight.

16. The method of claim 11 , wherein a shell of lithium cobalt phosphate having a tetrahedral phase is formed on a surface of the lithium cobalt oxide by the hydrothermal reaction.

17. The method of claim 11 , wherein the hydrothermal reaction is performed at a temperature of 200° C. to 400° C. and a pressure of 1 bar to 10 bar for 5 minutes to 20 minutes.

18. A secondary battery comprising a positive electrode including the positive electrode active material particle of claim 1 , a negative electrode, and an electrolyte.

19. The secondary battery of claim 18 , wherein the electrolyte includes electrolyte additives, wherein the electrolyte additives include at least one of ethylene carbonate, vinyl acetate, vinyl ethylene carbonate, thiophene, 1,3-propane sultone, succinic anhydride, or dinitrile additive, and
wherein the dinitrile additive is at least one of malononitrile, succinonitrile, glutaronitrile, adiponitrile, or phthalonitrile.

20. The secondary battery of claim 19 , wherein the dinitrile additive is included in an amount of 5% by weight or less based on the total weight of the electrolyte.

Assignees

• Lg Chemical Ltd

Inventors

• Park Younguk
• Jo Chi Ho
• Lee Bo Ram
• Park Sungbin
• Hur Hyuck
• Jung Wang Mo

Classifications

• C01G51/42

  containing alkali metals, e.g. LiCoO2 · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M4/366 Primary

  as layered products · CPC title

• H01M10/0567

  characterised by the additives · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title