Method for manufacturing positive electrode active material, positive electrode active material manufactured using the method, and rechargeable lithium battery comprising the positive electrode active material

Abstract

A method for manufacturing a positive electrode active material, a positive electrode active material manufactured using the method, and a rechargeable lithium battery including the positive electrode active material are provided. The method includes: performing a first mixing process at a first shear rate to form a mixture of a lithium transition metal complex oxide and graphene; and performing a second mixing process on the mixture at a second shear rate, wherein the first mixing process and the second mixing process are performed using a mixer including a pressure head and a rotating chamber, and the second shear rate is greater than the first shear rate.

Claims

1. A method comprising the following steps: A first mixing process is performed at a first shear rate to form a mixture of lithium transition metal composite oxide and graphene; and The mixture is subjected to a second mixing process at a second shear rate. in, Both the first and second mixing processes are performed using a mixer that includes a pressure head and a rotating chamber. The second shear rate is greater than the first shear rate. The first shear rate is defined by Equation 1, and The second shear rate is defined by Equation 2: Equation 1 First shear rate (s) -1 = First rotational speed of the rotating chamber / First gap, In equation 1, The first rotational speed is between 1000 mm / s and 6000 mm / s, and The first gap is the first gap space between the pressure head and the inner wall of the rotating chamber, and is greater than 0 mm and less than or equal to 1 cm; Equation 2 Second shear rate (s) -1 = Second rotational speed of the rotating chamber / Second gap, In equation 2, The second rotational speed is from 4000 mm / s to 18000 mm / s, and The second gap is the second gap space between the pressure head and the inner wall of the rotating chamber, and is greater than 0 mm and less than or equal to 1 cm. The method described herein is a method for manufacturing positive electrode active materials.

2. The method according to claim 1, wherein, The ratio of the first shear rate to the second shear rate is 1:1.2 to 1:3.

5.

3. The method according to claim 1, wherein, The graphene includes reduced graphene oxide.

4. The method according to claim 1, wherein, The weight ratio of the lithium transition metal composite oxide to the graphene is 99:1 to 99.99:0.

01.

5. The method according to claim 1, wherein, The first mixing process is carried out for 0.5 to 5 minutes.

6. The method according to claim 1, wherein, The second mixing process is carried out for 5 to 20 minutes.

7. The method according to claim 1, wherein, The pressure head has a diameter ranging from 10 mm to 2000 mm.

8. The method according to claim 1, wherein, Both the first mixing process and the second mixing process are dry processes.

9. The method according to claim 1, wherein, The first and second mixing processes require 350 Wh or less of power per kilogram of the manufactured positive electrode active material.

10. The method according to claim 1, wherein, The mixer includes a mechanical fusion unit.

11. A positive electrode active material, said positive electrode active material comprising: The core includes lithium transition metal complex oxides; as well as A carbon coating layer on the surface of the core. The positive electrode active material is prepared by the method according to any one of claims 1 to 10.

12. The positive electrode active material according to claim 11, wherein, The lithium transition metal composite oxide is a lithium nickel oxide, a lithium cobalt oxide, a lithium manganese oxide, a lithium iron phosphate compound, a cobalt-free lithium nickel manganese oxide, or a combination thereof.

13. The positive electrode active material according to claim 11, wherein, The carbon coating layer includes reduced graphene oxide.

14. The positive electrode active material according to claim 11, wherein, The carbon coating comprises graphene with a lateral dimension of 0.1 μm to 1000 μm and a thickness of 1 nm or less.

15. The positive electrode active material according to claim 11, wherein, Based on the total weight of 100wt% of the positive electrode active material, the amount of the carbon coating is from 0.01wt% to 1wt%.

16. The positive electrode active material according to claim 11, wherein, The carbon coating has a thickness of 0.1 nm to 50 nm.

17. The positive electrode active material according to claim 11, wherein, The positive electrode active material includes at least one of large particles and small particles.

18. A rechargeable lithium battery, said rechargeable lithium battery comprising: Positive electrode; negative electrode; as well as A diaphragm is located between the positive electrode and the negative electrode. The positive electrode includes a current collector and a layer of positive electrode active material on the current collector, and The positive electrode active material layer comprises the positive electrode active material according to any one of claims 11 to 17.

19. The rechargeable lithium battery according to claim 18, wherein, The positive electrode active material layer also includes a conductive material, and The weight ratio of the conductive material to the positive electrode active material is 1 / 99.5 to 1 / 97.

20. The rechargeable lithium battery according to claim 18, wherein, The density of the mixture of the positive electrode is from 3.0 g / cc to 5.0 g / cc.

Images