KR-20260063959-A - CATHODE ACTIVE MATERIAL PREPARED USING THE SAME AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

Abstract

The present invention relates to a positive electrode active material for a lithium secondary battery, wherein the lithium metal oxide is in the form of a secondary particle containing a primary particle and can satisfy the following equation 1. [Relationship 1] 2.20 ≤ {Porosity/(BET/D50^2)/100} ≤ 3.30 (Here, porosity is the percentage (%) of the total area of pores with an area of 3086.4 nm² or larger observed after recognizing pores with ImageJ in the cross-section relative to the cross-sectional area of the lithium metal oxide secondary particle, BET is the specific surface area ( m² /g) of the lithium metal oxide secondary particle, and D50 is the average particle size (μm) of the lithium metal oxide secondary particle.)

Inventors

• 이승재
• 김득수
• 박혜원
• 한슬기
• 정일록
• 송혜지
• 이효빈
• 박도협

Assignees

• (주)포스코퓨처엠

Dates

Publication Date

20260507

Application Date

20241031

Claims (9)

1. As a lithium metal oxide in the form of secondary particles containing primary particles, That which satisfies the following relationship 1, Cathode active material for lithium secondary batteries. [Relationship 1] 2.20 ≤ {Porosity/(BET/D50^2)/100} ≤ 3.30 (Here, porosity is the percentage (%) of the total area of pores with an area of 3086.4 nm² or larger observed after recognizing pores with ImageJ in the cross-section relative to the cross-sectional area of the lithium metal oxide secondary particle; BET is the specific surface area ( m² /g) of the lithium metal oxide secondary particle; and D50 is the average particle size (μm) of the lithium metal oxide secondary particle.)
2. In paragraph 1, That which satisfies the following relationship 2, Cathode active material for lithium secondary batteries. [Relationship 2] 55.0 ≤ {Grain Size / Porosity * BET^2} ≤ 90.0 (Here, porosity is the percentage (%) of the total area of pores with an area of 3086.4 nm² or larger observed after recognizing pores with ImageJ in the cross-section relative to the cross-sectional area of the lithium metal oxide secondary particle; BET is the specific surface area ( m² /g) of the lithium metal oxide secondary particle; and grain size is the average grain size (nm) of the lithium metal oxide.)
3. In paragraph 1, The lithium metal oxide comprises one or more doping elements selected from Al, Zr, V, Co, Mg, Ti, Y, Sr, Nb, Ba, Ca, B, W, Sc, Si, Fe, Mo, Ce, Hf, Ta, and La. Cathode active material for lithium secondary batteries.
4. In paragraph 3, The molar content of the doping element is less than 2.5 mol% (excluding 0) based on the total molar amount of metal excluding lithium of the above lithium metal oxide. Cathode active material for lithium secondary batteries.
5. In paragraph 1, The specific surface area of the lithium metal oxide is 0.80 to 1.5 m² /g, Cathode active material for lithium secondary batteries.
6. In paragraph 1, The crystal grain size of the lithium metal oxide is in the range of 90 to 120 nm. Cathode active material for lithium secondary batteries.
7. In paragraph 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery represented by the following chemical formula 1. [Chemical Formula 1] Li x Ni a Co b Mn c M d O 2 (Here, 0.90≤x≤1.20, 0.80≤a<1.0, 0≤b≤0.20, 0≤c≤0.20, 0≤d≤0.2, a+b+c+d=1, and M is one or more selected from Al, Zr, V, Co, Mg, Ti, Y, Sr, Nb, Ba, Ca, B, W, Sc, Si, Fe, Mo, Ce, Hf, Ta, and La.)
8. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 7.
9. A lithium secondary battery including a positive electrode according to paragraph 8.

Description

Cathode active material prepared using the same 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, which are composed of active materials capable of lithium ion intercalation and deintercalation, with an organic or polymer electrolyte charged between them. 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 transition metal oxide (hereinafter simply referred to as 'NCM-based lithium composite transition metal oxide') was developed in which a portion of the cobalt (Co) was substituted with nickel (Ni) and manganese (Mn). High-content nickel NCM cathode materials with a nickel content of 80% or more have the advantage of high capacity, but have the disadvantage of poor stability in cycle operation environments. To address this, research is being conducted to reduce reactivity with the electrolyte by doping or coating with various elements. However, due to chronic issues with these cathode active materials, such as structural stability and adverse reactions with the electrolyte, limitations are being encountered in increasing capacity, and significant improvements are still required. Therefore, there is a need to develop cathode active materials capable of realizing battery characteristics with excellent capacity and cycle life. Figure 1 shows a cross-sectional SEM image of a positive electrode active material according to Comparative Example 1 of the present invention. Figure 2 shows an image of Figure 1 converted to ImageJ. 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. 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 pres