Positive electrode active material, and positive electrode and lithium secondary battery containing the same

Abstract

The present invention relates to a positive electrode active material comprising a lithium transition metal oxide in single-particle form, and a positive electrode and a lithium secondary battery comprising the same, wherein the lithium transition metal oxide in single-particle form comprises an external interface forming the outer edge of the particle and an internal interface formed within the particle, and the single-particle positive electrode active material satisfies the condition 0 < length of internal interface / length of external interface < 0.4.

Claims

1. A positive electrode active material containing a lithium transition metal oxide in single-particle form, The lithium transition metal oxide in single-particle form includes an external interface forming the outer edge of the particle and an internal interface formed within the particle, satisfying the following formula 1. [Formula 1] 0 < length of internal interface / length of external interface < 0.4 The positive electrode active material wherein the length of the internal interface is the length obtained by subtracting the length of the interface measured from the EBSD band contrast map from the length of the interface measured from the electron backscatter diffraction (EBSD)-IPF map for the lithium transition metal oxide particles, and the length of the external interface is the length of the external interface of the transition metal oxide particles measured by SEM image resolution.

2. The lithium transition metal oxide in single-particle form further satisfies the following formula 2, wherein the positive electrode active material is as described in claim 1. [Formula 2] The length of the interface measured from the EBSD IPF map / the length of the interface measured from the EBSD band contrast map ≤ 1.4

3. The lithium transition metal oxide in single-particle form further satisfies the following formula 3, wherein the positive electrode active material is as described in claim 1. [Formula 3] 0 ≤ (length of internal interface / length of external interface) - (length of interface measured by (length of internal interface / EBSD band contrast)) ≤ 1

4. The cathode active material according to claim 1, wherein the length of the interface measured from the electron backscatter diffraction (EBSD)-IPF map includes the length of a weak interface contained in the single-particle lithium transition metal oxide particle, which differs only in atomic arrangement and has not undergone crystallinity collapse, and the length of a strong interface formed by the collapse of the layered structure.

5. The cathode active material according to claim 1, wherein the length of the interface measured from the EBSD band contrast map includes the length of the interface formed by the collapse of the layered structure contained in the single-particle lithium transition metal oxide particles.

6. The lithium transition metal oxide in single-particle form comprises 2 to 50 particles, as described in claim 1, for the positive electrode active material.

7. The positive electrode active material according to claim 1, wherein the lithium transition metal oxide is a lithium composite transition metal oxide containing nickel, cobalt, and manganese.

8. The positive electrode active material according to claim 1, wherein the lithium transition metal oxide is a lithium composite transition metal oxide represented by the following chemical formula 1. [Chemical formula 1] Li ａ Ni ｂ Co ｃ Mn ｄ M １ ｅ O ２ In the above chemical formula 1, M １ is one or more elements selected from the group consisting of Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, Sn, Y, Zn, F, P, and S, and satisfies 0.9 ≤ a ≤ 1.1, 0.6 ≤ b < 1, 0 < c < 0.4, 0 < d < 0.4, 0 ≤ e < 0.1, and b + c + d + e = 1.

9. The positive electrode active material according to claim 1, wherein the lithium transition metal oxide is a lithium composite transition metal oxide represented by the following chemical formula 2. [Chemical formula 2] Li ａ Ni ｂ Co ｃ Mn ｄ O ２ In the above chemical formula 2, 0.9 ≤ a ≤ 1.1, 0.6 ≤ b < 1, 0 < c < 0.4, 0 < d < 0.4, and b + c + d = 1.

10. From the aforementioned single-particle form of lithium transition metal oxide, the average particle size (D ５０ ) further contains a small single-particle form of a second lithium transition metal oxide, The positive electrode active material according to claim 1, having a bimodal particle size distribution.

11. The positive electrode active material according to claim 10, wherein the second lithium transition metal oxide is a lithium composite transition metal oxide represented by the following chemical formula 3. [Chemical formula 3] Li ａ３ Ni ｂ３ Co ｃ３ Mn ｄ３ M ３ ｅ３ O ２ In the above chemical formula 3, M ３ is one or more elements selected from the group consisting of Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, Sn, Y, Zn, F, P, and S, and satisfies 0.9 ≤ a3 ≤ 1.1, 0.6 ≤ b3 < 1, 0 < c3 < 0.4, 0 < d3 < 0.4, 0 ≤ e3 < 0.1, and b3 + c3 + d3 + e3 = 1.

12. The positive electrode active material according to claim 10, wherein the weight ratio of the lithium transition metal oxide to the second lithium transition metal oxide is 1 to 9:

1.

13. The rolled density is 3.50 g / cm³. ２ ~3.90 g / cm ２ The positive electrode active material according to claim 10.

14. A positive electrode comprising the positive electrode active material according to any one of claims 1 to 13.

15. A lithium secondary battery comprising the positive electrode described in claim 14.

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