KR-20260064253-A - CATHODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY AND METHOD OF MANUFACTURING THEREOF AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

Abstract

The present invention relates to a positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same. The positive electrode active material for a lithium secondary battery comprises a lithium metal oxide and a coating layer located on at least a portion of the surface of the lithium metal oxide, and satisfies Formula 1 below. <Equation 1> pH 1st / pH 2nd ≥ 1.18 (In Equation 1 above, pH 1st and pH 2nd represent the pH value before the addition of 0.1N HCl and the pH value at the first equivalence point after the addition of 0.1N HCl, respectively, in the residual lithium titration graph of the cathode active material.)

Inventors

• 서성화
• 김성인
• 박혜정
• 이수진
• 박정현
• 신동기

Assignees

• (주)포스코퓨처엠

Dates

Publication Date

20260507

Application Date

20241031

Claims (14)

1. lithium metal oxide; and It includes a coating layer located in at least a portion of the surface of the lithium metal oxide, and A positive electrode active material for a lithium secondary battery satisfying the following formula 1. <Equation 1> pH 1st / pH 2nd ≥ 1.18 (In Equation 1 above, pH 1st and pH 2nd represent the pH value before the addition of 0.1N HCl and the pH value at the first equivalence point after the addition of 0.1N HCl, respectively, in the residual lithium titration graph of the cathode active material.)
2. In Article 1, The above coating layer is a positive electrode active material for a lithium secondary battery comprising an aluminum-based material.
3. In Article 1, A positive electrode active material for a lithium secondary battery satisfying the following Equation 2. <Equation 2> pH 1st / pH 3rd ≤ 2.4550 (In Equation 2 above, pH 1st and pH 3rd represent the pH value before the addition of 0.1N HCl and the pH value at the second equivalence point after the addition of 0.1N HCl, respectively, in the residual lithium titration graph of the cathode active material.)
4. In Article 1, A positive electrode active material for a lithium secondary battery satisfying the following Equation 3. <Equation 3> (pH 1st - pH 3nd ) /pH 2nd ≥ 0.695 (In Equation 3 above, pH1st, pH2nd, and pH3rd represent the pH value before the addition of 0.1N HCl and the pH values of the first and second equivalence points after the addition of 0.1N HCl, respectively, in the residual lithium titration graph of the cathode active material.)
5. In Article 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery in the form of a single particle.
6. In Article 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery satisfying the following chemical formula 1. <Chemical Formula 1> Li a Ni x Co y Mn z M k O 2 (In the above chemical formula 1, 0.9 ≤ a ≤ 1.1, 0.3 ≤ x ≤ 0.73, 0.01 ≤ y ≤ 0.3, 0.01 ≤ z ≤ 0.4, 0 ≤ k ≤ 0.2, x + y + z + k = 1, and In this case, M is one or more selected from Al, Zr, B, Y, Ti, Nb, W, V, Zn, Na, K, Mg and combinations thereof)
7. A step of preparing a mixture by mixing a precursor containing a transition metal and a lithium raw material; A step of forming a lithium metal oxide by calcining the above mixture; and The method includes the step of mixing the lithium metal oxide and the coating raw material and then heat-treating to form a coating layer located on at least a portion of the surface of the lithium metal oxide. The above coating raw material is a method for manufacturing a positive electrode active material for a lithium secondary battery satisfying Formula 4 below. <Equation 4> 19.5 ≤ (CT BET /CT pH ) ≤25.5 (In Equation 4 above, CT BE and CT pH represent the BET (Brunauer-Emmett-Teller) specific surface area of the coating raw material and the pH value of the coating raw material, respectively.)
8. In Article 7, The above coating raw material is a method for manufacturing a positive electrode active material for a lithium secondary battery satisfying Formula 5 below. <Equation 5> (CT BET × CT pH ) ≥ 450.0 (In Equation 5 above, CT BET and CT pH represent the BET (Brunauer-Emmett-Teller) specific surface area of the coating raw material and the pH value of the coating raw material, respectively.)
9. In Article 7, The above coating raw material is a method for manufacturing a positive electrode active material for a lithium secondary battery containing an aluminum-containing material.
10. In Article 9, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the above aluminum-containing material is one or more selected from Al(OH) 3 , Al2 ( SO4 ) 3 · xH2O , Al2O3, Al( NO3 ) 3 · 9H2O , AlCl3 , and C2H5O4Al .
11. In Article 7, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the BET specific surface area (CT BET ) of the above-mentioned coating raw material is 90 m² /g or more.
12. In Article 7, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the pH value (CT pH ) of the above-mentioned coating raw material is 4.5 or higher.
13. In Article 7, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the above heat treatment is performed at 300 to 500 ℃.
14. A lithium secondary battery comprising a positive active material according to any one of claims 1 to 6.

Description

Cathode active material for lithium secondary battery, method of manufacturing the same, and lithium secondary battery comprising the same The present invention relates to a positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery comprising the same. Lithium cobalt oxide ( LiCoO2 ), lithium nickel oxide ( LiNiO2 ), lithium manganese oxide ( LiMnO2 or LiMnO4, etc.), and lithium iron phosphate compounds ( LiFePO4 ) have been used as cathode active materials for lithium secondary batteries. Among these, lithium cobalt oxide has the advantages of high operating voltage and excellent capacity characteristics; however, it is difficult to apply it commercially to high-capacity batteries due to the high cost and unstable supply of cobalt, which is the raw material. Lithium nickel oxide has poor structural stability, making it difficult to achieve sufficient lifespan characteristics. Meanwhile, lithium manganese oxide has excellent stability but has the problem of poor capacity characteristics. Accordingly, lithium composite transition metal oxides containing two or more transition metals have been developed to compensate for the problems of lithium transition metal oxides containing Ni, Co, or Mn alone. Among these, lithium nickel cobalt manganese oxide containing Ni, Co, and Mn is widely used in the field of electric vehicle batteries. Conventional lithium nickel cobalt manganese oxide was generally in the form of spherical secondary particles formed by the aggregation of tens to hundreds of primary particles. However, in the case of lithium nickel cobalt manganese oxide in the form of secondary particles, there are problems such as particle breakage where primary particles detach during the rolling process in cathode manufacturing, and cracks occurring inside the particles during the charging and discharging process. If particle breakage or cracking occurs in the cathode active material, the contact area with the electrolyte increases, leading to increased gas generation and active material degradation due to side reactions with the electrolyte, which in turn reduces lifespan characteristics. Furthermore, with the recent increase in demand for high-output, high-capacity batteries, such as those for electric vehicles, there is a trend toward gradually increasing the nickel content in cathode active materials (so-called "high-nickel"). While increasing the nickel content in cathode active materials improves initial capacity characteristics, repeated charging and discharging generates a large amount of highly reactive Ni +4 ions, leading to structural breakdown of the cathode active material. This accelerates the degradation rate of the material, resulting in reduced lifespan characteristics and decreased battery safety. To solve the above problem, a technology has been proposed to manufacture a cathode active material in the form of a single particle rather than a secondary particle by increasing the calcination temperature during the production of lithium nickel cobalt manganese oxide. In the case of a cathode active material in the form of a single particle, the contact area with the electrolyte is smaller compared to conventional cathode active materials in the form of secondary particles, so there are fewer side reactions with the electrolyte, and the particle strength is excellent, resulting in less particle breakage during electrode manufacturing. Therefore, when a cathode active material in the form of a single particle is applied, there are advantages such as reduced gas generation and excellent lifespan characteristics. However, due to the rising prices of raw materials such as nickel and cobalt, and the thermal propagation issues that arise when nickel accounts for an excessively high content, the development of raw materials other than nickel, particularly coating materials, is being actively pursued. Figure 1 is an SEM image of a positive electrode active material prepared according to an embodiment of the present invention. 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