Nickel-based lithium metal composite oxide, method for manufacturing the same, and lithium secondary battery including a positive electrode containing the same

Abstract

To provide a nickel-based lithium metal composite oxide and a manufacturing method thereof, and a lithium secondary battery having a positive electrode that contains the nickel-based lithium metal composite oxide.SOLUTION: A nickel-based lithium metal composite oxide, a manufacturing method thereof, and a lithium secondary battery having a positive electrode containing the nickel-based lithium metal composite oxide are disclosed. The nickel-based lithium metal composite oxide comprises primary particles, and secondary particles including aggregates of the primary particles. In the nickel-based lithium metal composite oxide, a nickel content is 50 mol% or more to a transition metal total content. The secondary particles include large secondary particles of 10 μm or more in particle size, and small secondary particles of 5 μm or less in particle size. The large secondary particles are larger than the small secondary particles in nickel content.SELECTED DRAWING: Figure 1

Claims

1. A nickel-based lithium metal composite oxide containing secondary particles including aggregates of primary particles, wherein the nickel content is 50 mol% or more, based on the total transition metal content in a nickel-based lithium metal composite oxide. The aforementioned secondary particles include large secondary particles with an average particle size (D50) of 10 μm or more, and small secondary particles with an average particle size (D50) of 5 μm or less. A nickel-based lithium metal composite oxide wherein the nickel content of the large secondary particles is greater than the nickel content of the small secondary particles, The aforementioned large secondary particles are a compound represented by the following chemical formula 1-1, and the aforementioned small secondary particles are a compound represented by the following chemical formula 1-2. In a dQ / dV charge-discharge differential curve relating to a lithium secondary battery comprising the aforementioned nickel-based lithium metal composite oxide, the ratio (A2 / A1) of the discharge peak intensity (A2) to the charge peak intensity (A1), which is expressed as a voltage of 4.1V to 4.25V at a current of 1C, is 1.1 or greater for the nickel-based lithium metal composite oxide: 【Chemistry 1-1】 In the above chemical formula 1-1, M is boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zirconium (Zr), or a combination thereof. 0.95 ≤ a ≤ 1.3, 0.88 ≤ 1 - x - y - z ≤ 0.96, 0.01 ≤ x ≤ 0.08, 0.001 ≤ y ≤ 0.05, 0 ≤ z ≤ 0.01, [Chemistry 1-2] In the above chemical formula 1-2, M is boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zirconium (Zr), or a combination thereof. 0.95 ≤ a ≤ 1.3, 0.75 ≤ 1 - x - y - z ≤ 0.85, 0.01 ≤ x ≤ 0.05, 0.001 ≤ y ≤ 0.05, and 0 ≤ z ≤ 0.

01.

2. The nickel-based lithium metal composite oxide according to claim 1, wherein the charging peak is a peak indicated at 4.17V to 4.25V, and the discharging peak is a peak indicated at 4.14V to 4.17V.

3. The nickel-based lithium metal composite oxide according to claim 1, wherein the ratio (A2 / A1) of the discharge peak intensity (A2) to the dQ / dV charge peak intensity (A1) is 1.1 to 1.

5.

4. The nickel-based lithium metal composite oxide according to claim 1, wherein the difference in nickel content between the large secondary particles and the small secondary particles is 10 mol% or more.

5. The nickel-based lithium metal composite oxide according to claim 1, wherein the nickel content in the large secondary particles is 85 to 99 mol%, based on the total content of the transition metal.

6. The nickel-based lithium metal composite oxide according to claim 1, wherein the nickel content in the small secondary particles is 75 to 89 mol%, based on the total transition metal content of the small secondary particles.

7. The nickel-based lithium metal composite oxide according to claim 1, wherein the average particle size (D50) of the large secondary particles is 10 μm to 17 μm.

8. The nickel-based lithium metal composite oxide according to claim 1, wherein the average particle size (D50) of the small secondary particles is 2 μm to 5 μm.

9. The nickel-based lithium metal composite oxide according to claim 1, wherein the content of the large secondary particles is 30 to 90 parts by weight, based on the total content of the large secondary particles and the small secondary particles, which is 100 parts by weight.

10. A large-grained nickel-based metal hydroxide with a nickel content of 50 mol% or more (based on the total transition metal content), a small-grained nickel-based metal hydroxide with a nickel content of 50 mol% or more (based on the total transition metal content), and a lithium precursor are mixed to obtain a precursor mixture, which is then subjected to heat treatment. A method for producing a nickel-based lithium metal composite oxide, comprising the step of obtaining a nickel-based lithium metal composite oxide according to any one of claims 1 to 9.

11. The method for producing a nickel-based lithium metal composite oxide according to claim 10, wherein the heat treatment is performed at 650°C to 800°C.

12. The method for producing a nickel-based lithium metal composite oxide according to claim 10, wherein the large-grained nickel-based metal hydroxide has a higher nickel content than the small-grained nickel-based metal hydroxide, and the difference in nickel content is 10 mol% or more.

13. The nickel content of the aforementioned large-grained nickel-based metal hydroxide is 85 to 99 mol%, based on the total transition metal content of the large-grained nickel-based metal hydroxide. The method for producing a nickel-based lithium metal composite oxide according to claim 10, wherein the nickel content of the small-grained nickel-based metal hydroxide is 75 to 89 mol%, based on the total transition metal content of the small-grained nickel-based metal hydroxide.

14. The method for producing a nickel-based lithium metal composite oxide according to claim 10, wherein the lithium precursor is lithium hydroxide, lithium fluoride, lithium carbonate, or a mixture thereof.

15. A lithium secondary battery comprising a positive electrode, a negative electrode, and an electrolyte interposed between them, all containing a nickel-based lithium metal composite oxide as described in any one of claims 1 to 9.

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