Positive electrode active material, method of preparing the same, positive electrode including the positive electrode active material, and secondary battery including the positive electrode

Patent metadata

Field	Value
Publication number	US-11894558-B2
Application number	US-201917042518-A
Country	US
Kind code	B2
Filing date	Apr 5, 2019
Priority date	Apr 6, 2018
Publication date	Feb 6, 2024
Grant date	Feb 6, 2024

Abstract

A positive electrode active material includes a core and a coating layer disposed on the core, wherein the core includes Li 1+x MO 2+y , wherein M is at least one element selected from the group consisting of nickel (Ni), cobalt (Co), and copper (Cu), and 1≤x≤5 and 0≤y≤2, and the coating layer includes carbon-based particles, wherein the carbon-based particle includes a structure in which a plurality of graphene sheets are connected, the carbon-based particle has an oxygen content of 1 wt % or more in the carbon-based particle, and the carbon-based particle has a D/G peak ratio of 1.55 or less during Raman spectrum measurement. A method of preparing the positive electrode active material, a positive electrode including the positive electrode active material, and a secondary battery including the positive electrode are also provided.

First claim

The invention claimed is:

1. A positive electrode active material comprising a core and a coating layer disposed on the core,
wherein the core comprises Li 1+x MO 2+y , wherein M is at least one element selected from the group consisting of nickel (Ni), cobalt (Co), and copper (Cu), and 1≤x≤5 and 0≤y≤2, and
the coating layer comprises carbon-based particles,
wherein the carbon-based particle comprises a structure in which a plurality of graphene sheets are connected,
the carbon-based particle has an oxygen content of 1 wt % or more in the carbon-based particle, and
the carbon-based particle has a D/G peak ratio of 1.55 or less during Raman spectrum measurement.

2. The positive electrode active material of claim 1 , wherein the Li 1+x MO 2+y comprises at least one selected from the group consisting of Li 2 NiO 2 , Li 6 CoO 4 , and Li 2 CuO 2 .

3. The positive electrode active material of claim 1 , wherein a weight ratio of the core to the coating layer is in a range of 94:6 to 99.5:0.5.

4. The positive electrode active material of claim 1 , wherein each of the graphene sheets have a lateral size of 200 nm or less.

5. The positive electrode active material of claim 1 , wherein the carbon-based particle has a value calculated by Equation 1 of 0.12 or less:



b
-
a



a

[

Equation
⁢

⁢
1

]

wherein, in Equation 1, a is a specific surface area (m 2 /g) of the carbon-based particle which is measured by a nitrogen adsorption Brunauer-Emmett-Teller (BET) method, and b is an iodine adsorption value (mg/g) of the carbon-based particle.

6. The positive electrode active material of claim 1 , further comprising a connection portion connected to at least a part of the graphene sheets of the plurality of graphene sheets,
wherein the connection portion has a non-graphene shape.

7. The positive electrode active material of claim 6 , wherein at least a portion of each of the plurality of graphene sheets is connected to the connection portion.

8. The positive electrode active material of claim 1 , wherein each of the graphene sheets have an average thickness of 10 nm or less.

9. The positive electrode active material of claim 1 , wherein the carbon-based particle has a specific surface area (m 2 /g) measured by a nitrogen adsorption BET method of 200 m 2 /g or more.

10. A method of preparing a positive electrode active material, the method comprising:
preparing carbon-based particles, and disposing the carbon-based particles on a core,
wherein the preparing of the carbon-based particles comprises preparing preliminary carbon-based particles, and modifying the preliminary carbon-based particles by an oxidation treatment,
wherein the modifying of the preliminary carbon-based particles by the oxidation treatment comprises at least one of
a) performing a first heat treatment of the preliminary carbon-based particles at a temperature of 200° C. to 800° C. in at least one atmosphere of an oxygen atmosphere and an air atmosphere; and
b) reacting the preliminary carbon-based particles with an acidic vapor at 120° C. to 300° C., and
the core comprises Li 1+x MO 2+y , wherein M is at least one element selected from the group consisting of nickel (Ni), cobalt (Co), and copper (Cu), and 1≤x≤5 and 0≤y≤2.

11. The method of claim 10 , wherein the preparing of the preliminary carbon-based particles comprises pyrolysis of acetylene gas at a temperature of 1,500° C. or more.

12. The method of claim 10 , wherein the preliminary carbon-based particles comprise at least one selected from the group consisting of acetylene black, furnace black, thermal black, channel black, and lamp black.

13. The method of claim 12 , wherein the preliminary carbon-based particles comprise acetylene black.

14. The method of claim 10 , further comprising performing a second heat treatment of the preliminary carbon-based particles modified by the oxidation treatment at a temperature of 500° C. or more in an inert atmosphere, after the modifying of the preliminary carbon-based particles by the oxidation treatment.

15. A positive electrode comprising the positive electrode active material of claim 1 .

16. A secondary battery comprising:
the positive electrode of claim 15 ;
a negative electrode;
a separator disposed between the positive electrode and the negative electrode; and
an electrolyte.

17. The secondary battery of claim 16 , wherein the negative electrode comprises a negative electrode active material layer, and
the negative electrode active material layer comprises SiO x (0<x<2).

18. The positive electrode active material of claim 8 , wherein the average thickness is 0.34 nm to 10 nm.

19. The positive electrode material of claim 9 , wherein the specific surface area is 200 m 2 /g to 1,100 m 2 /g.

20. The method of claim 11 , wherein the pyrolysis of the acetylene gas is performed at the temperature of 1,500° C. to 2,200° C.

Assignees

• Lg Chemical Ltd
• Lg Energy Solution Ltd

Inventors

• Kim Seul Ki
• Jeon Hye Lim
• Kim Tae Gon
• Jung Wang Mo
• Lee Sang Wook

Classifications

• H01M4/525 Primary

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

• H01M4/0471

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

• H01M4/133

  Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title

• H01M4/1393

  of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title

• H01M2004/027

  Negative electrodes · CPC title