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KR-102963888-B1 - CATHODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

KR102963888B1KR 102963888 B1KR102963888 B1KR 102963888B1KR-102963888-B1

Abstract

The present invention relates to a positive electrode active material for a lithium secondary battery comprising a first lithium metal oxide containing 80 mol% or more of nickel based on the total molar amount of metal excluding lithium, and a second lithium metal oxide containing 80 mol% or more of nickel based on the total molar amount of metal excluding lithium, wherein the average particle size (D50) of the first lithium metal oxide is larger than the average particle size (D50) of the second lithium metal oxide, and the change in pore size showing a maximum peak in a pore size distribution curve measured by the BJH (Barrett-Joyner-Halenda) method before and after the application of a pressure of 6.78 tonf/cm² is 0.35 nm or less.

Inventors

  • 한슬기
  • 정일록
  • 이승재
  • 김득수

Assignees

  • (주)포스코퓨처엠

Dates

Publication Date
20260511
Application Date
20230926

Claims (16)

  1. It comprises a first lithium metal oxide containing 80 mol% or more of nickel based on the total molar amount of metals excluding lithium, and a second lithium metal oxide containing 80 mol% or more of nickel based on the total molar amount of metals excluding lithium, and The average particle size (D50) of the first lithium metal oxide is larger than the average particle size (D50) of the second lithium metal oxide, and The change in pore size exhibiting a maximum peak in the pore size distribution curve measured by the BJH (Barrett-Joyner-Halenda) method before and after the application of a pressure of 6.78 tonf/ cm² is 0.35 nm or less, and A B-containing coating layer disposed on the surface of the first lithium metal oxide, and further comprising a Co-containing coating layer or a Co and Al-containing coating layer disposed on the surface of the second lithium metal oxide. Cathode active material for lithium secondary batteries.
  2. In paragraph 1, The above positive active material is a positive active material for a lithium secondary battery in which the pore size distribution curve measured by the BJH method exhibits a unimodal shape.
  3. In paragraph 1, The above positive active material is a positive active material for a lithium secondary battery in which the pore size distribution curve measured by the BJH method after applying a pressure of 6.78 tonf/ cm² exhibits a unimodal shape.
  4. In paragraph 1, A positive electrode active material for a lithium secondary battery having a pore size of 3.13 to 3.4 nm that exhibits a maximum peak in the pore size distribution curve measured by the BJH method.
  5. In paragraph 1, A positive electrode active material for a lithium secondary battery having an average pore size of 6.4 to 6.62 nm as measured by the BJH method.
  6. In paragraph 1, A positive electrode active material for a lithium secondary battery having a BET specific surface area of 0.19 to 0.25 m² /g.
  7. In paragraph 1, A positive electrode active material for a lithium secondary battery having a pellet density of 3.65 g/ cm³ or higher.
  8. In paragraph 1, A positive electrode active material for a lithium secondary battery, wherein the first lithium metal oxide is a secondary particle and the second lithium metal oxide is a single particle.
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  11. In paragraph 1, A positive electrode active material for a lithium secondary battery, wherein the content of B in the coating layer is 300 to 900 ppm based on the total weight of the first lithium metal oxide.
  12. In paragraph 1, A positive electrode active material for a lithium secondary battery, wherein the content of Co in the coating layer is 9,600 to 16,000 ppm based on the total weight of the second lithium metal oxide.
  13. In paragraph 1, A positive electrode active material for a lithium secondary battery, wherein the average particle size (D50) of the first lithium metal oxide is 9 to 18 μm and the average particle size (D50) of the second lithium metal oxide is 3 to 9 μm.
  14. In paragraph 1, A positive electrode active material for a lithium secondary battery, wherein the weight ratio of the first lithium metal oxide and the second lithium metal oxide is 9:1 to 7:3 (first lithium metal oxide: second lithium metal oxide).
  15. A positive electrode for a lithium secondary battery comprising a positive electrode active material according to any one of claims 1 to 8 and claims 11 to 14.
  16. A lithium secondary battery comprising a positive electrode for a lithium secondary battery according to claim 15.

Description

Cathode active material for lithium secondary battery and lithium secondary battery comprising the same The present invention relates to a positive electrode active material for a lithium secondary battery and a lithium secondary battery comprising the same. As electric vehicles become commercialized, the need for high capacity, high energy density, and safety in lithium-ion batteries is growing. Accordingly, LiCoO2 cathode active materials were widely used in the past, but recently, development is being carried out on high-nickel lithium nickel-cobalt-manganese oxide, which enables high capacity and has excellent price competitiveness. In addition, development is underway for so-called bimodal cathode active materials capable of improving rolling density by mixing small and large particle sizes of cathode active materials to achieve high energy density. However, high-nickel lithium nickel-cobalt-manganese oxide inherently has weak grain strength and low structural stability. Consequently, when the electrode is rolled more intensely to further improve the rolling density of the bimodal cathode active material, there is a problem in that capacity characteristics deteriorate due to the collapse of the cathode active material's surface structure. In other words, increasing the rolling density to raise the energy density of the bimodal cathode active material leads to a degradation of capacity characteristics, resulting in a problem where the effect of improving battery energy density becomes insignificant. Furthermore, the breakdown of the surface structure of such positive electrode active materials increases the generation of fine particles, which intensifies the oxidation reaction of the electrolyte—an exothermic reaction—under high voltage conditions, thereby causing a problem that degrades the thermal safety of the battery. Figure 1 is a pore size distribution curve of the positive electrode active material prepared according to Example 1, measured by the BJH method. Figure 2 is a pore size distribution curve of the positive electrode active material prepared according to Example 2, measured by the BJH method. Figure 3 is a pore size distribution curve of the positive electrode active material prepared according to Comparative Example 1, measured by the BJH method. Figure 4 is a pore size distribution curve of the positive electrode active material prepared according to Comparative Example 2, measured by the BJH method. Figure 5 is a pore size distribution curve of the positive electrode active material prepared according to Comparative Example 3, measured by the BJH method. Figure 6 is a pore size distribution curve of the positive electrode active material prepared according to Comparative Example 4, measured by the BJH method. Figure 7 is a pore size distribution curve of the positive electrode active material prepared according to Comparative Example 5, measured by the BJH method. Terms such as first, second, and third are used to describe various parts, components, regions, layers, and/or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention. The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and/or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and/or components. When it is stated that one part is "above" or "on" another part, it may be directly above or on the other part, or other parts may be involved in between. In contrast, when it is stated that one part is "directly above" another part, no other parts are interposed in between. Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined. Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %. In this specification, the term “combination(s) of these” described in the Markush-type expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-type expressi