Positive electrode active material and lithium secondary battery

Abstract

To provide a lithium-manganese-rich-based positive electrode active material which is capable oof realizing a high capacity per volume by improving volume density while realizing a high capacity and realizes a long lifetime characteristic, and a rechargeable lithium battery including the same.SOLUTION: There are disclosed, a positive electrode active material, and a rechargeable lithium battery. The positive electrode active material includes a first positive electrode active material including a first lithium-manganese-rich composite oxide in which a molar ratio of lithium to a total metal excluding lithium is about 1.06 to about 1.2 and a manganese content based on 100 mol% of a total metal excluding lithium is greater than or equal to about 30 mol%, and a second positive electrode active material including a second lithium-manganese-rich composite oxide in which a molar ratio of lithium to a total metal excluding lithium is greater than about 1.2 and less than or equal to about 2 and a manganese content based on 100 mol% of a total metal excluding lithium is greater than or equal to about 30 mol%, and having the average particle diameter (D50) smaller than the average particle diameter (D50) of the first positive electrode active material.SELECTED DRAWING: Figure 1

Claims

1. A first positive electrode active material containing a first lithium-manganese-rich composite oxide, wherein the molar ratio of lithium to the total metal excluding lithium is 1.06 or more and 1.2 or less, and the manganese content is 30 mol% or more per 100 mol% of the total metal excluding lithium, The second lithium-manganese-rich composite oxide contains a lithium molar ratio of more than 1.2 to 2 or less relative to the total metal excluding lithium, and a manganese content of 30 mol% or more relative to 100 mol% of the total metal excluding lithium, and the average particle size of the first positive electrode active material is D 50 ) Average particle size (D 50 A positive electrode active material comprising a second positive electrode active material having ).

2. The positive electrode active material according to claim 1, wherein, with respect to 100% by weight of the total sum of the first positive electrode active material and the second positive electrode active material, the first positive electrode active material is present in an amount greater than 50% by weight and less than 100% by weight, and the second positive electrode active material is present in an amount greater than 0% by weight and less than 50% by weight.

3. The positive electrode active material according to claim 1, wherein, with respect to 100% by weight of the total sum of the first positive electrode active material and the second positive electrode active material, the first positive electrode active material is present in an amount of 60% to 95% by weight, and the second positive electrode active material is present in an amount of 5% to 40% by weight.

4. Average particle size of the first positive electrode active material (D 50 ) is between 5 μm and 20 μm, Average particle size of the second positive electrode active material (D 50 The positive electrode active material according to claim 1, wherein the diameter of the material is 1 μm or more and 7 μm or less.

5. The first lithium-manganese-rich composite oxide of the first positive electrode active material has a molar ratio of lithium to the total metal excluding lithium that is greater than 1.1 and less than or equal to 1.

2. The positive electrode active material according to claim 1, wherein the second lithium-manganese-rich composite oxide of the second positive electrode active material has a molar ratio of lithium to the total metal excluding lithium that is greater than 1.2 and less than or equal to 1.

5.

6. The first lithium-manganese-rich composite oxide of the first positive electrode active material has a nickel content of 45 mol% or more relative to 100 mol% of the total metal excluding lithium. The positive electrode active material according to claim 1, wherein the second lithium-manganese-rich composite oxide of the second positive electrode active material has a nickel content of less than 45 mol% relative to 100 mol% of the total metal excluding lithium.

7. The first lithium-manganese-rich composite oxide of the first positive electrode active material has a nickel content of 45 mol% to 70 mol% and a manganese content of 30 mol% to 55 mol% relative to a total of 100 mol% of nickel and manganese. The positive electrode active material according to claim 1, wherein the second lithium-manganese-rich composite oxide of the second positive electrode active material has a nickel content of 10 mol% to less than 45 mol% and a manganese content of more than 55 mol% to 90 mol% per 100 mol% of nickel and manganese.

8. The positive electrode active material according to claim 1, wherein in the overall mixture of the first positive electrode active material and the second positive electrode active material, the molar ratio of lithium to the total metal excluding lithium is 1.1 to 1.3, the nickel content is 35 mol% to 65 mol% of the total nickel and manganese 100 mol%, and the manganese content is 35 mol% to 65 mol%.

9. The positive electrode active material according to claim 1, wherein the first lithium-manganese-rich composite oxide of the first positive electrode active material is represented by a metal oxide containing at least one of chemical formula 1 and chemical formula 2: [Chemical formula 1] Li 1+x1 (N y1 Mn z1 M 1 1-y1-z1 ) 1-x1 O 2-b1 X 1 b1 In the above chemical formula 1, 0.03 ≤ x1 ≤ 0.09, 0.45 ≤ y1 ≤ 0.7, 0.3 ≤ z1 ≤ 0.55, and 0 ≤ b1 ≤ 0.1, M 1 is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zr, and X 1 is one or more elements selected from F, P, and S. [Chemical formula 2] (1-12)(i) y2 7N z2 7. 2 1-y2-z2 9 2-b2 8 2 b2 )kx2(ii 2 (7n t1 7. 2 1-t1 )9 3-b3 8 2 b3 )) In the above chemical formula 2, 0.06 ≤ x² ≤ 0.2, 0.5 ≤ y² ≤ 1.0, 0 ≤ z² ≤ 0.5, 0 ≤ b² ≤ 0.1, 0.9 ≤ t¹ ≤ 1, and 0 ≤ b³ ≤ 0.1, M 2 is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zr, and X 2 is one or more elements selected from F, P, and S.

10. The second lithium-manganese-rich composite oxide of the second positive electrode active material is represented by at least one of chemical formula 3 or chemical formula 4, according to claim 1: [Chemical formula 3] Li 1+x3 (N y3 Mn z3 M 3 1-y3-z3 ) 1-x3 O 2-b4 X 3 b4 In the above chemical formula 3, 0.09 < x3 ≤ 0.33, 0.1 ≤ y3 < 0.45, 0.55 < z3 ≤ 0.9, and 0 ≤ b4 ≤ 0.1, M 3 is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zr, and X 3 is one or more elements selected from F, P, and S. [Chemical formula 4] (-x4)(iii) y4 7N z4 7. 4 1-y4-z4 9 2-b5 8 4 b5 )kx5Li 2 (7n t2 7. 4 1-t2 )9 3-b6 8 4 b6 )) In the above chemical formula 4, 0.2 < x₄ ≤ 1, 0.5 ≤ y₄ ≤ 1.0, 0 ≤ z₄ ≤ 0.5, 0 ≤ b₅ ≤ 0.1, 0.9 ≤ t₂ ≤ 1, and 0 ≤ b₶ ≤ 0.1, M 4 is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zr, and X 4 is one or more elements selected from F, P, and S.

11. The positive electrode active material according to claim 1, wherein in the first lithium-manganese-rich composite oxide and the second lithium-manganese-rich composite oxide, the cobalt content relative to 100 mol% of the total metal excluding lithium is 0 mol% to 1 mol%.

12. The first positive electrode active material is in the form of secondary particles, which are aggregated from multiple primary particles. The positive electrode active material according to claim 1, wherein the second positive electrode active material is in the form of secondary particulate matter, single particulate matter, or a combination thereof.

13. Average particle size of the first positive electrode active material (D 50 ) from the average particle size of the second positive electrode active material (D 50 The positive electrode active material according to claim 1, wherein the value obtained by subtracting ) is 6 μm or less.

14. Average particle size of the first positive electrode active material (D 50 ) from the average particle size of the second positive electrode active material (D 50 The positive electrode active material according to claim 11, wherein the value obtained by subtracting ) is 2 μm to 5 μm.

15. The positive electrode active material according to claim 1, wherein the pellet density of the positive electrode active material is 2.9 g / cc or more.

16. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 15, The negative electrode and, A lithium secondary battery containing an electrolyte.

17. The lithium secondary battery according to claim 16, wherein the capacity per unit volume of the positive electrode is 550 mAh / cc or more.

18. The average discharge voltage of the lithium secondary battery is 3.8V (vs. Li / Li + The lithium secondary battery according to claim 16, wherein the above conditions are met.

19. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 15, The negative electrode and, An all-solid-state secondary battery comprising a solid electrolyte layer located between the positive electrode and the negative electrode.

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