JP-2026514366-A - Cathode material, cathode containing the same, and lithium secondary battery

Abstract

The present invention relates to a positive electrode material comprising a single-particulate first positive electrode active material and a second positive electrode active material which is in the form of secondary particles and has a larger average particle size ( D50 ) than the first positive electrode active material, wherein when a pressure of 6,500 kgf/ cm² is applied to the positive electrode material, the volume of particles with a particle size of 1 μm or less relative to the total volume of particles present in the positive electrode material is 10% or less, and to a positive electrode for a lithium secondary battery and a lithium secondary battery containing the same.

Inventors

• ジン・ヒ・ジュン
• ジン・ウク・ジュ
• ソル・ジン・キム
• ジュン・ソン・キム
• サン・ウォン・ウ
• ジェ・スン・リム
• ジョン・ウォン・キム
• グワン・ソク・チェ

Assignees

• エルジー・ケム・リミテッド

Dates

Publication Date

20260511

Application Date

20240409

Priority Date

20230410

Claims (11)

1. A single-particle first positive electrode active material, A second positive electrode active material which is in the form of secondary particles and has a larger average particle size (D 50 ) than the first positive electrode active material, Includes, A positive electrode material in which, when a pressure of 6,500 kgf/ cm² is applied to the positive electrode material, the volume of particles with a particle size of 1 μm or less relative to the total volume of particles present in the positive electrode material is 10% or less.
2. The cathode material according to claim 1, having a bimodal particle size distribution.
3. The cathode material according to claim 1, wherein the average particle size (D 50 ) of the first cathode active material is 50% or less based on the average particle size (D 50 ) of the second cathode active material.
4. The cathode material according to claim 1, wherein the single-particulate material is single-crystalline.
5. The positive electrode material according to claim 1, wherein the weight ratio of the first positive electrode active material to the second positive electrode active material is 1:0.1 to 10.
6. The positive electrode material according to claim 1, wherein the average particle size (D 50 ) of the first positive electrode active material is 1 μm or more and 10 μm or less.
7. The cathode material according to claim 1, wherein the average particle size (D 50 ) of the second cathode active material is 6 μm or more and 25 μm or less.
8. The cathode material according to claim 1, wherein the first cathode active material has a composition represented by the following chemical formula 1. [Chemical formula 1] Li 1+a1 Ni x1 Co y1 M 1 z1 M 2 w1 O 2 In the aforementioned chemical formula 1, M1 is one or more elements selected from the group consisting of Mn and Al. M2 is one or more elements selected from the group consisting of B, Ba, Ce, Cr, F, Mg, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, S, Sr, Ta, La, and Hf. -0.1 ≤ a1 ≤ 0.3, 0.6 ≤ x1 < 1.0, 0 < y1 < 0.4, 0 < z1 < 0.4, 0 ≤ w1 ≤ 0.1.
9. The cathode material according to claim 1, wherein the second cathode active material has a composition represented by the following chemical formula 2. [Chemical formula 2] Li 1+a2 Ni x2 Co y2 M 3 z2 M 4 w2 O 2 In the aforementioned chemical formula 2, M3 is one or more elements selected from the group consisting of Mn and Al. M4 is one or more elements selected from the group consisting of B, Ba, Ce, Cr, F, Mg, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, S, Sr, Ta, La, and Hf. -0.1 ≤ a² ≤ 0.3, 0.6 ≤ x² < 1.0, 0 < y² < 0.4, 0 < z² < 0.4, 0 ≤ w² ≤ 0.1.
10. A positive electrode comprising a positive electrode active material layer containing the positive electrode material described in any one of claims 1 to 9.
11. A lithium secondary battery comprising the positive electrode described in claim 10.

Description

This application claims priority under Korean Patent Application No. 10-2023-0047003 dated April 10, 2023, and all content disclosed in the said Korean Patent Application is incorporated herein by reference. This invention relates to a positive electrode material for lithium secondary batteries, a positive electrode containing the same, and a lithium secondary battery. As technological development and demand for mobile devices increase, the demand for rechargeable batteries as an energy source is rapidly growing. Among these rechargeable batteries, lithium-ion batteries, which possess high energy density and voltage, long cycle life, and low self-discharge rates, have been commercialized and are widely used. Lithium-complex transition metal oxides are used as positive electrode active materials in lithium secondary batteries, and among them, lithium-cobalt-complex metal oxides such as LiCoO₂ are mainly used because they have a high operating voltage and excellent capacity characteristics. However, LiCoO₂ has poor thermal properties due to the destabilization of its crystal structure by delithiation. In addition, LiCoO₂ is expensive, which limits its use in large quantities as a power source in fields such as electric vehicles. As alternatives to the aforementioned LiCoO2 , lithium manganese composite metal oxides ( such as LiMnO2 or LiMn2O4 ), lithium iron phosphate compounds (such as LiFePO4 ), and lithium nickel composite metal oxides (such as LiNiO2 ) have been developed. Among these, research and development on lithium nickel composite metal oxides, which have a high reversible capacity of approximately 200 mAh/g and facilitate the realization of high-capacity batteries, are being conducted more actively. However , compared to LiCoO2 , LiNiO2 has inferior thermal stability, and if an internal short circuit occurs due to external pressure while charged, the positive electrode active material itself decomposes, causing the battery to rupture and ignite. Therefore, as a method to maintain the excellent reversible capacity of LiNiO2 and improve its low thermal stability, lithium transition metal oxides in which some of the Ni is substituted with Co, Mn, or Al have been developed. In lithium-ion batteries where lithium-compound transition metal oxides, particularly those containing high levels of nickel (Ni-rich), are used as the positive electrode active material, the battery capacity, the presence or absence of high power output, and the presence or absence of gas generation at high temperatures are influenced not only by the chemical properties of the positive electrode active material, such as its composition, impurity content, and the content of lithium by-products present on its surface, but also by its physical properties, such as the size, surface area, density, and shape of the positive electrode active material particles. Generally, to maximize the volumetric energy density of a battery, a method is used in which large-particle positive electrode active material and small-particle positive electrode active material are mixed. The small-particle positive electrode active material fills the gaps between the large-particle positive electrode active material particles, thereby improving the volumetric energy density of the battery. To produce a more dense positive electrode active material layer, a method of rolling the positive electrode active material layer using a roll press is employed. However, in this case, due to the difference in particle strength between the large-particle and small-particle positive electrode active materials, excessive cracking occurs in the particles with relatively weaker particle strength during rolling. This not only causes the particles to lose their original shape but also increases the contact area with the electrolyte excessively, resulting in a problem of reduced battery life when applied to a battery. Therefore, there is a need to develop cathode materials that can improve volumetric energy density and suppress particle cracking during rolling for cathode manufacturing, thereby improving lifetime characteristics. Korean Published Patent No. 2021-0117212 This is an SEM image of the first positive electrode active material produced in manufacturing example 2.This is an SEM image of the second cathode active material produced in Production Example 1.This is an SEM image of the small-particle size secondary particulate cathode active material produced in Comparative Manufacturing Example 1.This is an SEM image of the small-particle, single-particle positive electrode active material produced in comparative manufacturing example 2.This is a particle size distribution curve measured by PSA before and after applying a pressure of 6,500 kgf/ cm² to the cathode material manufactured in Example 1.This is a particle size distribution curve measured by PSA before and after applying a pressure of 6,500 kgf/ cm² to the cathode material manufactured in Example 2.This is a partic