Positive electrode for lithium secondary batteries, and lithium secondary batteries containing the same

Abstract

To provide a positive electrode for a lithium secondary battery, for realizing a prevention of deterioration and a long life of the lithium secondary battery.SOLUTION: A positive electrode active material of a lithium secondary battery, includes: a first positive electrode active material including a first lithium nickel-cobalt-based composite oxide, having in a form of second particles composed of a plurality of primary particles, and having an average particle diameter (D50) of a second particles of 10 μm to 30 μm; a second positive electrode active material including a second lithium nickel-cobalt-based composite oxide, in a form of second particles composed of the plurality of primary particles, and having an average particle diameter (D50) of the second particles is 5 μm to 9 μm; and a third positive electrode active material including a third lithium nickel-cobalt-based composite oxide, in a form of single particles, and having an average particle diameter (D50) of the single particles is 0.5 μm to 4 μm.SELECTED DRAWING: Figure 1

Claims

1. It contains a first lithium nickel-cobalt composite oxide and has a secondary particle form consisting of a plurality of primary particles, and the average particle size of the secondary particles (D 50 The first positive electrode active material has a diameter of 10 μm to 30 μm; It contains a second lithium nickel-cobalt composite oxide and has a secondary particle form consisting of a plurality of primary particles, and the average particle size of the secondary particles (D 50 The second positive electrode active material has a diameter of 5 μm to 9 μm; and It contains a third lithium nickel-cobalt composite oxide, is in single-particle form, and the average particle size of the single particle is D 50 The third positive electrode active material has a diameter of 0.5 μm to 4 μm; Includes, The average particle size (D 50) is the volume-average particle size. Positive electrode active material for lithium secondary batteries that satisfies the following relational equation 1: [Relationship 1] Co 2 >Co 1 >Co 3 In the relational expression 1, Co 1 is the molar percentage content of cobalt with respect to 100 mol% of the metal excluding lithium in the first lithium nickel-cobalt-based composite oxide, Co 2 is the molar percentage content of cobalt with respect to 100 mol% of the metal excluding lithium in the second lithium nickel-cobalt-based composite oxide, Co 3 is the molar percentage content of cobalt with respect to 100 mol% of the metal excluding lithium in the third lithium nickel-cobalt-based composite oxide.

2. The positive electrode active material for a lithium secondary battery according to claim 1, comprising 60 to 90% by weight of the first positive electrode active material relative to 100% by weight of the total of the first positive electrode active material, the second positive electrode active material, and the third positive electrode active material.

3. The positive electrode active material for a lithium secondary battery according to claim 1, comprising 5 to 20% by weight of the second positive electrode active material relative to 100% by weight of the total of the first positive electrode active material, the second positive electrode active material, and the third positive electrode active material.

4. The positive electrode active material for a lithium secondary battery according to claim 1, comprising 5 to 20% by weight of the third positive electrode active material relative to 100% by weight of the total of the first positive electrode active material, the second positive electrode active material, and the third positive electrode active material.

5. The aforementioned Co 2 is Co 1 The positive electrode active material for a lithium secondary battery according to claim 1, wherein the amount is 1.1 to 2 times the amount of the other material.

6. The aforementioned Co 1 is Co 3 The positive electrode active material for a lithium secondary battery according to claim 1, wherein the amount is 1.1 to 3 times the amount of the above.

7. The aforementioned Co 1 The positive electrode active material for lithium secondary batteries according to claim 1, wherein the amount is 5 mol% to 20 mol%.

8. The aforementioned Co 2 The positive electrode active material for lithium secondary batteries according to claim 1, wherein the amount is 10 mol% to 30 mol%.

9. The aforementioned Co 3 The positive electrode active material for lithium secondary batteries according to claim 1, wherein the amount is 1 mol% to 15 mol%.

10. The aforementioned Co 2 Co 1 The positive electrode active material for lithium secondary batteries according to claim 1, which is 1 mol% to 10 mol% or more.

11. The aforementioned Co 1 Co 3 The positive electrode active material for lithium secondary batteries according to claim 1, which is 1 mol% to 10 mol% or more.

12. A positive electrode for a lithium secondary battery, comprising a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector, The positive electrode for a lithium secondary battery comprises a positive electrode active material layer according to any one of claims 1 to 11.

13. The positive electrode for a lithium secondary battery according to claim 12, wherein the density of the positive electrode active material layer is 3.4 g / cc to 3.9 g / cc.

14. The positive electrode for a lithium secondary battery according to claim 12, wherein the amount of cracked first positive electrode active material in the positive electrode active material layer is 0 to 10 percent of the total first positive electrode active material.

15. The positive electrode for a lithium secondary battery according to claim 12, wherein the portion occupied by Ni³⁺ is 1 to 30 area % of the total area 100% of the cross-section of the positive electrode active material layer.

16. A step of preparing a composition in which, based on 100% by weight of the total of the first positive electrode active material, the second positive electrode active material, and the third positive electrode active material, the content of the first positive electrode active material is 60 to 90% by weight, the content of the second positive electrode active material is 5 to 20% by weight, and the content of the third positive electrode active material is 5 to 20% by weight; The step of coating the current collector with the composition; and After drying, the rolling stage; A method for manufacturing a positive electrode for a lithium secondary battery, including, The first positive electrode active material contains a first lithium nickel-cobalt composite oxide and is in the form of secondary particles consisting of a plurality of primary particles, wherein the average particle size of the secondary particles (D 50 The particle size of the second positive electrode active material is 10 μm to 30 μm, and the second positive electrode active material contains a second lithium nickel-cobalt composite oxide and is in the form of secondary particles consisting of a plurality of primary particles, and the average particle size of the secondary particles (D 50 The particle size of the third positive electrode active material is 5 μm to 9 μm, and the third positive electrode active material contains a third lithium nickel-cobalt composite oxide, is in single-particle form, and the average particle size of the single particles is D 50 A method for manufacturing a positive electrode for a lithium secondary battery, wherein the particle size is 0.5 μm to 4 μm, the average particle size (D 50) is the volume average particle size, and the following relational expression 1 is satisfied. [Relationship 1] Co 2 >Co 1 >Co 3 In the aforementioned relational equation 1, Co 1 This is the molar content of cobalt relative to 100 mol% of the metal excluding lithium in the first lithium nickel-cobalt composite oxide, and Co 2 This is the molar content of cobalt relative to 100 mol% of the metal excluding lithium in the second lithium nickel-cobalt composite oxide, and Co 3 This represents the molar content of cobalt relative to 100 mol% of the metal excluding lithium in the third lithium nickel-cobalt composite oxide.

17. Positive electrode for lithium secondary battery according to claim 12; Negative electrode; and electrolyte Lithium-ion batteries, including lithium-ion batteries.

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