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KR-102963845-B1 - CATHODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY, MANUFACTURING METHOD OF THE SAME AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

KR102963845B1KR 102963845 B1KR102963845 B1KR 102963845B1KR-102963845-B1

Abstract

The present invention relates to a positive electrode active material for a lithium secondary battery that is in a bimodal form comprising a large particle size lithium metal oxide and a small particle size lithium metal oxide and satisfies Formula 1 below. [Equation 1] Dv50 / Dn50 ≥ 2.0 In the above Equation 1, Dv50 is the average particle size based on 50% of the cumulative volume of the positive active material, and Dn50 is the average particle size based on 50% of the cumulative number of the positive active material.

Inventors

  • 강춘구
  • 이한주
  • 송혜지
  • 이효빈
  • 김도형
  • 김득수
  • 최권영

Assignees

  • (주)포스코퓨처엠

Dates

Publication Date
20260511
Application Date
20230831

Claims (9)

  1. It is a bimodal form including large-particle lithium metal oxide and small-particle lithium metal oxide, and The above large-particle lithium metal oxide and small-particle lithium metal oxide have the same or different compositions and are independently represented by the following chemical formula 1, and The number-based average particle size (Dn50) of the above-mentioned bimodal lithium metal oxide is 3.5 to 6 μm, and A positive electrode active material for a lithium secondary battery satisfying the following Formula 1: [Equation 1] Dv50 / Dn50 ≥ 2.0 In Equation 1 above, Dv50 is the average particle size based on 50% by volume of the cumulative volume of the positive active material, and Dn50 is the average particle size based on 50% by number of the cumulative number of the positive active material: [Chemical Formula 1] Li a [Ni x Co y Mn z M w ]O 2 In the above chemical formula 1, 0.8≤a≤1.2, 0.5≤x≤0.9, 0≤y≤0.2, 0≤z≤0.4, 0≤w≤0.2, x+y+z+w=1, and M is Zr, Al, B, Y, Mg, Ti, Nb, W, Sc, Si, V, Fe, Y, Mo, Ce, Hf, Ta, La, Sr, or a combination thereof.
  2. In paragraph 1, A positive electrode active material for a lithium secondary battery satisfying the following Equation 2: [Equation 2] (Dv50 / Dn50) * PD ≥ 4.0 In Equation 2 above, PD is the press density (g/ cm³ ) of the positive electrode active material, and the press density is evaluated under the condition that 10g of the positive electrode active material is introduced into a cylindrical mold using a GEOPYC 1365 (Micromeritics) instrument and the mold is pressurized at a pressure of 108N. Dv50 is the average particle size based on 50% of the cumulative volume of the positive active material, and Dn50 is the average particle size based on 50% of the cumulative number of the positive active material.
  3. In paragraph 1, A positive electrode active material for a lithium secondary battery satisfying the following Equation 3: [Equation 3] 0.7 ≤ Span ≤ 1.0 In Equation 3 above, the variance is evaluated as (Dv90-Dv10)/Dv50, and Dv90 is the average particle size based on 90 volume% of the cumulative volume of the positive active material, Dv10 is the average particle size based on 10 volume% of the cumulative volume of the positive active material, and Dv50 is the average particle size based on 50 volume% of the cumulative volume of the positive active material.
  4. In paragraph 1, A positive electrode active material for a lithium secondary battery, wherein, based on 100 weight% of the total positive electrode active material, the large particle size lithium metal oxide is 60 to 70 weight%.
  5. In paragraph 1, A positive electrode active material for a lithium secondary battery, wherein the average particle size (Dn50) based on the number of positive electrode active materials is 3.5 to 6 μm.
  6. In paragraph 1, A positive electrode active material for a lithium secondary battery, wherein the volume-based average particle size (Dv50) of the above positive electrode active material is 6 to 8 μm.
  7. delete
  8. A positive electrode for a lithium secondary battery comprising a positive electrode active material according to any one of claims 1 to 6.
  9. A lithium secondary battery comprising a positive electrode for a lithium secondary battery according to claim 8.

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. In a lithium secondary battery, electrical energy is produced by oxidation and reduction reactions when lithium ions are inserted into or removed from the positive and negative electrodes, while an organic or polymer electrolyte is charged between the positive and negative electrodes, which are composed of active materials capable of lithium ion intercalation and deintercalation. Lithium cobalt oxide ( LiCoO2 ), lithium nickel oxide ( LiNiO2 ), lithium manganese oxide ( LiMnO2 or LiMn2O4 , etc. ), and lithium iron phosphate compounds ( LiFePO4 ) have been used as cathode active materials for lithium secondary batteries. Among these, lithium cobalt oxide ( LiCoO2 ) is widely used and applied as a cathode active material for high voltage applications due to its advantages of high operating voltage and excellent capacity characteristics. However, due to the rising price and supply instability of cobalt (Co), there are limitations to its mass use as a power source in fields such as electric vehicles, leading to the need for the development of cathode active materials that can replace it. Accordingly, a nickel-cobalt-manganese-based lithium composite metal oxide (hereinafter simply referred to as 'NCM-based lithium composite metal oxide') was developed in which a portion of the cobalt (Co) was replaced with nickel (Ni) and manganese (Mn). However, conventionally developed NCM-based lithium composite metal oxides generally have a secondary particle form in which primary particles are aggregated, and have a large specific surface area, low particle strength, and high lithium byproduct content, which results in a large amount of gas generation during cell operation and consequently a decrease in lifespan and stability. Figure 1 is a graph of particle size based on cumulative volume according to bimodal form. Figure 2 is a particle size graph based on the cumulative number according to the bimodal shape. 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 expression, and means including any one or more selected from the group consisting of said components. Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. 1. Cathode active material A positive electrode active material for a lithium secondary battery according to one embodiment of the present invention comprises a bimodal lithium metal oxide. Accordingly, it offers excellent lifespan and safety, and can achieve high energy density of the electrode. In this specification, “secondary particle” means an aggregate, i.e., a secondary str