Positive electrode active material for secondary battery, method for preparing the same and lithium secondary battery comprising the same

Patent metadata

Field	Value
Publication number	US-12040484-B2
Application number	US-201916657275-A
Country	US
Kind code	B2
Filing date	Oct 18, 2019
Priority date	Oct 26, 2018
Publication date	Jul 16, 2024
Grant date	Jul 16, 2024

Abstract

A positive electrode active material for a secondary battery is provided, which includes a lithium composite transition metal oxide including nickel (Ni), cobalt (Co), and manganese (Mn), wherein a particle of the lithium composite transition metal oxide includes a core portion and a resistance portion formed on a surface of the core portion, and is composed of a single particle, wherein the core portion has a layered crystal structure of space group R-3m, and the resistance portion has a cubic rock-salt structure of space group Fm-3m.

First claim

The invention claimed is:

1. A positive electrode active material for a secondary battery, the positive electrode active material is a lithium composite transition metal oxide represented by the following formula:
Li p Ni 1−(x1+y1+z1) Co x1 Mn y1 M a z1 O 2+δ   [Formula 1]

wherein, M a is at least one selected from the group consisting of Al, Zr, Ti, Mg, Ta, Nb, Mo, Cr, Ba, Sr, and Ca, 1≤p≤1.3, 0<x1≤0.5, 0<y1<0.5, 0≤z1≤0.1, and −0.1≤δ≤1,
wherein a particle of the lithium composite transition metal oxide comprises a core portion and a resistance portion formed on a surface of the core portion, and is composed of a single particle, and
wherein the core portion has a layered crystal structure of space group R-3m, and the resistance portion has a cubic rock-salt structure of space group Fm-3m.

2. The positive electrode active material for a secondary battery of claim 1 , wherein the resistance portion is formed on a part or entirety of the surface of the core portion.

3. The positive electrode active material for a secondary battery of claim 1 , wherein the core portion has a crystallite size of 180 nm to 400 nm.

4. The positive electrode active material for a secondary battery of claim 1 , wherein an amount of the nickel (Ni) in a total amount of metals excluding lithium (Li) is less than 60 mol %, a main peak with a maximum heat flow is measured at 280° C. or more, and the maximum heat flow is 8 W/g or less when the positive electrode active material is thermally analyzed by differential scanning calorimetry (DSC).

5. The positive electrode active material for a secondary battery of claim 1 , wherein a main peak with a maximum heat flow is measured at 210° C. or more, and the maximum heat flow is 15 W/g or less when the positive electrode active material is thermally analyzed by differential scanning calorimetry (DSC).

6. A positive electrode for a secondary battery, the positive electrode comprising the positive electrode active material of claim 1 .

7. A lithium secondary battery comprising the positive electrode of claim 6 .

8. The positive electrode active material for a secondary battery of claim 1 , wherein an amount of the nickel (Ni) in a total amount of metals excluding lithium (Li) is less than 60 mol %, a main peak with a maximum heat flow is measured at 280° ° C. to 300° C., and the maximum heat flow is 8 W/g or less when the positive electrode active material is thermally analyzed by differential scanning calorimetry (DSC).

9. The positive electrode active material for a secondary battery of claim 1 , wherein a main peak with a maximum heat flow is measured at 210° C. to 250° C., and the maximum heat flow is 15 W/g or less when the positive electrode active material is thermally analyzed by differential scanning calorimetry (DSC).

10. The positive electrode active material for a secondary battery of claim 1 , wherein the lithium composite transition metal oxide particle is composed of a primary particle having an average particle diameter (D 50 ) of 3 μm to 10 μm, and
wherein an amount of the Ni relative to a total amount of metals excluding lithium (Li) in the lithium composite transition metal oxide is 80 mol % or more.

11. A method of preparing the positive electrode active material for the secondary battery of claim 1 , comprising:
preparing a positive electrode active material precursor including nickel (Ni), cobalt (Co), and manganese (Mn) in which an amount of the nickel (Ni) in a total amount of metals is less than 60 mol %;
mixing the positive electrode active material precursor and a lithium raw material, and performing primary sintering on the mixture at a primary sintering temperature of 980° C. or more to form a primary sintered product; and
performing secondary sintering on the primary sintered product at a secondary sintering temperature of 900° C. or less to form the lithium composite transition metal oxide,
wherein the particle of the lithium composite transition metal oxide is composed of the single particle and the particle of the lithium composite transition metal oxide comprises the core portion having the layered crystal structure of space group R-3m; and the resistance portion which is formed on the surface of the core portion and has the cubic rock-salt structure of space group Fm-3m.

12. The method of claim 11 , wherein the primary sintering temperature is in a range of 990° C. to 1,050° C.

13. The method of claim 11 , wherein the secondary sintering temperature is in a range of 600° C. to 900° C.

14. The method of claim 11 , further comprising milling the primary sintered product after the primary sintering and before the secondary sintering.

15. The method of claim 11 , wherein the positive electrode active material precursor is a secondary particle in which primary particles are aggregated.

16. The method of claim 11 , wherein the secondary sintering is performed such that the lithium composite transition metal oxide particle is composed of a primary particle having an average particle diameter (D 50 ) of 1 μm to 20 μm.

17. The method of claim 11 , wherein the secondary sintering is performed such that the core portion has a crystallite size of 180 nm to 400 nm.

18. A method of preparing a positive electrode active material for the secondary battery of claim 1 , comprising:
preparing a positive electrode active material precursor including nickel (Ni), cobalt (Co), and manganese (Mn) in which an amount of the nickel (Ni) in a total amount of metals is 60 mol % or more;
mixing the positive electrode active material precursor and a lithium raw material, and performing primary sintering on the mixture at a primary sintering temperature of 850° C. or more to form a primary sintered product; and
performing secondary sintering on the primary sintered product at a secondary sintering temperature of 800° C. or less to form the lithium composite transition metal oxide,
wherein the particle of the lithium composite transition metal oxide is composed of the single particle and the particle of the lithium composite transition metal oxide comprises the core portion having the layered crystal structure of space group R-3m; and the resistance portion which is formed on the surface of the core portion and has the cubic rock-salt structure of space group Fm-3m.

19. The method of claim 18 , wherein the primary sintering temperature is in a range of 850° C. to 1,000° ° C.

20. The method of claim 18 , wherein the secondary sintering temperature is in a range of 500° C. to 800° C.

Assignees

• Lg Chemical Ltd
• Lg Energy Solution Ltd

Inventors

• Han Gi Beom
• Park Sang Min
• Kim Ji Hye
• Yoo Tae Gu
• Jung Wang Mo

Classifications

• H01M4/366

  as layered products · CPC title

• H01M4/0471 Primary

  involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M10/0525

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