KR-20260064106-A - POSITIVE ACTIVE MATERIAL AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

Abstract

This specification relates to a positive electrode active material and a lithium secondary battery containing the same. More specifically, this specification relates to a positive electrode active material and a lithium secondary battery containing the same, which improves electrochemical properties and stability by removing lithium-containing impurities present on the surface of a lithium composite oxide without a washing process.

Inventors

• 최진혁
• 배진호
• 신세희
• 이슬기
• 김진규

Assignees

• 주식회사 에코프로비엠

Dates

Publication Date

20260507

Application Date

20241031

Claims (15)

1. As a positive electrode active material comprising a lithium composite oxide capable of lithium intercalation and deintercalation, The above lithium composite oxide contains boron and sulfur, and A coating layer containing a sulfur compound is present on at least a portion of the surface of the above lithium composite oxide, Positive active material.
2. In paragraph 1, The above lithium composite oxide comprises at least one transition metal selected from nickel, cobalt, manganese, and aluminum, Positive active material.
3. In paragraph 2, The above lithium composite oxide is a transition metal excluding lithium in which the nickel content is 50 mol% or more, Positive active material.
4. In paragraph 2, In the above lithium composite oxide, the aluminum content is greater than the boron content, Positive active material.
5. In paragraph 2, In the above lithium composite oxide, at least one of aluminum, boron, and sulfur is concentrated on the surface portion of the lithium composite oxide, Positive active material.
6. In paragraph 1, The above sulfur compound includes Li₂SO₄ , Positive active material.
7. In paragraph 6, The above lithium composite oxide has a peak in at least one region selected from the group consisting of 2θ values of Cu-Kα XRD analysis of 22.1°±0.1°, 22.3°±0.1°, 25.8°±0.1°, and 28.3°±0.1°, Positive active material.
8. In paragraph 1, The above lithium composite oxide has a LiOH elution amount of less than 3,279 ppm as measured by a neutralization titration method using HCl, Positive active material.
9. In paragraph 1, The above lithium composite oxide is one in which the sum of the a-axis lattice constant and the c-axis lattice constant is less than 17.0785 Å, Positive active material.
10. In paragraph 1, The above lithium composite oxide is represented by the following chemical formula 1, [Chemical Formula 1] Li a Ni 1-(b+c+d+e) M1 b M2 c Al d B e O 2 (Here, M1 is at least one selected from Co and Mn, and M2 is at least one selected from Ba, Ce, Hf, Ta, Cr, F, Mg, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd and Cu, and 0.5≤a≤1.5, 0≤b≤0.20, 0≤c≤0.20, 0<d≤0.20, 0<e≤0.10) Positive active material.
11. In paragraph 1, The above coating layer further comprises at least one compound represented by the following chemical formula 2, [Chemical Formula 2] Li x M3 y S w O z (Here, M3 is at least one selected from Ni, Mn, Co, Fe, Cu, Nb, Mo, Ti, B, Al, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, P, Eu, Sm, W, Ce, V, Ba, Ta, Sn, Hf, Ce, Gd and Nd, and 0≤x≤8, 0<y≤8, 0≤w≤8, 2≤z≤13) Positive active material.
12. (a) Step of preparing a lithium composite oxide; (b) a step of applying a solution containing a boron-based compound and a sulfate-based compound to the surface of the lithium composite oxide; and (c) a step of firing at a temperature of less than 350℃; comprising, Method for manufacturing positive electrode active material.
13. In Paragraph 12, The above sulfate-based compound is aluminum sulfate, Method for manufacturing positive electrode active material.
14. In Paragraph 12, The content of unreacted residual LiOH and Li₂CO₃ after calcination in step (c) above is 63.3% or less compared to before calcination, Method for manufacturing positive electrode active material.
15. A positive active material comprising any one of claims 1 to 11, Lithium secondary battery.

Description

Positive active material and lithium secondary battery comprising the same This specification relates to a positive electrode active material and a lithium secondary battery containing the same. More specifically, this specification relates to a positive electrode active material and a lithium secondary battery containing the same, which improves electrochemical properties and stability by removing lithium-containing impurities present on the surface of a lithium composite oxide without a washing process. A battery stores electrical power by using materials capable of electrochemical reactions at the positive and negative electrodes. A representative example of such a battery is the lithium secondary battery, which stores electrical energy based on the difference in chemical potential when lithium ions intercalate or deintercalate at the positive and negative electrodes. The above lithium secondary battery is manufactured by using materials capable of reversible intercalation/deintercalation of lithium ions as positive and negative active materials, and by filling an organic electrolyte or a polymer electrolyte between the positive and negative electrodes. Lithium composite oxides are used as positive electrode active materials for lithium secondary batteries, and examples include LiCoO2 , LiMn2O4 , LiNiO2 , LiMnO2 , or composite oxides composed of Ni, Co, Mn, or Al , as described in Korean Patent Publication No. 10-2015-0069334 (published June 23, 2015). Among the above-mentioned cathode active materials, LiCoO2 is the most widely used due to its excellent lifespan characteristics and charge/discharge efficiency, but it has the disadvantage of having limited price competitiveness because it is expensive due to the resource limitations of cobalt used as a raw material. Lithium manganese oxides such as LiMnO2andLiMn2O4 have the advantages of excellent thermal stability and low cost, but they have problems such as low capacity and poor high-temperature characteristics. In addition, LiNiO2 -based cathode active materials exhibit high discharge capacity battery characteristics, but synthesis is difficult due to cation mixing between Li and transition metals, and consequently, there are significant problems with rate characteristics. In addition, depending on the degree of such cation mixing , a large amount of Li byproducts is generated, and most of these Li byproducts consist of compounds of LiOH and Li₂CO₃ , which cause gelation problems during the manufacture of anode paste and gas generation during charge and discharge after electrode manufacturing. Residual Li₂CO₃ not only increases the swelling phenomenon of the cell, thereby reducing the cycle life , but also causes the battery to swell. To compensate for these shortcomings, the demand for High-Ni cathode active materials with a Ni content of 50% or more as cathode active materials for secondary batteries has begun to increase. However, while these High-Ni cathode active materials exhibit high capacity characteristics, there is a problem in that structural instability caused by Li/Ni cation mixing occurs as the Ni content in the cathode active material increases. Due to this structural instability of the cathode active material, the lithium secondary battery can rapidly degrade not only at high temperatures but also at room temperature. Therefore, there is a need to develop cathode active materials to address the issues of these High-Ni cathode active materials. FIG. 1 shows the XRD measurement results for a positive electrode active material according to one embodiment of the present specification; FIG. 2 shows an SEM image of a positive electrode active material according to one embodiment of the present specification; FIG. 3 is a graph showing the characteristics of a positive electrode active material according to one embodiment of the present specification; FIG. 4 shows an SEM image of a positive electrode active material according to one embodiment of the present specification; FIG. 5 shows the electrochemical characteristics of a battery including a positive electrode active material according to one embodiment of the present specification. For convenience of understanding this specification, specific terms are defined herein. Unless otherwise defined herein, scientific and technical terms used herein shall have the meanings generally understood by those skilled in the art. Furthermore, unless specifically indicated in the context, terms in their singular form shall be understood to include their plural form, and terms in their plural form shall be understood to include their singular form. Hereinafter, a positive electrode active material for a lithium secondary battery with improved electrochemical properties and stability according to the present specification and a lithium secondary battery containing the same will be described in more detail. positive electrode active material A positive electrode active material according to one aspect of th