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US-20260128299-A1 - Positive Electrode Active Material, and Positive Electrode and Lithium Secondary Battery Including the Same

US20260128299A1US 20260128299 A1US20260128299 A1US 20260128299A1US-20260128299-A1

Abstract

A positive electrode active material includes: (1) a lithium nickel-based transition metal oxide with a large particle diameter; and (2) a lithium nickel-based transition metal oxide with a small particle diameter. The lithium nickel-based transition metal oxide with a large particle diameter is in the form of a secondary particle that is an aggregate of primary particles. The lithium nickel-based transition metal oxide with a small particle diameter is in the form of a single particle formed of one nodule and/or a quasi-single particle that is a composite of 30 or less nodules. The lithium nickel-based transition metal oxide with a large particle diameter has a D 50 of 5 μm to 30 μm, and a Y value defined by the factors of the particle size distribution characteristics is 2.2 or less. The positive electrode active material is applied to a positive electrode to provide a lithium secondary battery.

Inventors

  • Min Kwak
  • Hyeong II Kim
  • Seul Ki CHAE
  • Byung Chun Park

Assignees

  • LG ENERGY SOLUTION, LTD.

Dates

Publication Date
20260507
Application Date
20231222
Priority Date
20221226

Claims (10)

  1. 1 . A positive electrode active material comprising: a lithium nickel-based transition metal oxide with a large particle diameter and a lithium nickel-based transition metal oxide with a small particle diameter, wherein the lithium nickel-based transition metal oxide with a large particle diameter is in the form of a secondary particle that is an aggregate of primary particles, wherein the lithium nickel-based transition metal oxide with a small particle diameter is in the form of at least one of a single particle formed of one nodule and a quasi-single particle that is a composite of 30 or less nodules, and wherein the lithium nickel-based transition metal oxide with a large particle diameter has a D 50 of from 5 μm to 30 μm, and a Y value of 2.2 or less, wherein the Y value is defined by a following Equation 1: Y = I max D / ( D FWHM × R L ) , ( 1 ) wherein: I D max and D FWHM are values obtained from a volume cumulative particle size distribution graph obtained from particle size analysis (PSD) of the lithium nickel-based transition metal oxide with a large particle diameter; D FWHM is a full width at half maximum (FWHM) of a peak, and I D max is a maximum value of a peak; R L refers to a weight fraction of the lithium nickel-based transition metal oxide with a large particle diameter among a total of the positive electrode active material, and is a rational number greater than 0 and less than 1; and I D max , D FWHM , and R L are dimensionless numbers having no unit.
  2. 2 . The positive electrode active material according to claim 1 , wherein the Y value is from 0.7 to 2.0.
  3. 3 . The positive electrode active material according to claim 1 , wherein R L is from 0.4 to 0.9.
  4. 4 . The positive electrode active material according to claim 1 , wherein I D max /D FWHM is from 0.5 to 3.0.
  5. 5 . The positive electrode active material according to claim 1 , wherein a mixed weight ratio of the large-particle-diameter lithium nickel-based transition metal oxide to the small-particle-diameter lithium nickel-based transition metal oxide is from 9:1 to 3:7.
  6. 6 . The positive electrode active material according to claim 1 , wherein the positive electrode active material has an aspect ratio of from 0.60 to 0.99, and a roundness of from 0.60 to 0.99.
  7. 7 . The positive electrode active material according to claim 1 , wherein each of the lithium nickel-based transition metal oxide with a large particle diameter and the lithium nickel-based transition metal oxide with a small particle diameter is independently represented by a following chemical formula (1): wherein: M 1 includes one or more selected from Mn and Al; M 2 includes one or more selected from the group consisting of W, Zr, Y, Ba, Ca, Ti, V, Mg, Ta and Nb; X includes one or more selected from the group consisting of N, P, S, F and Cl; and 0≤x≤0.5, 0.5≤a<1, 0<b≤0.4, 0<c≤0.4, 0≤d≤0.05, and 0≤e≤0.05.
  8. 8 . The positive electrode active material according to claim 1 , wherein each of the lithium nickel-based transition metal oxide with a large particle diameter and the lithium nickel-based transition metal oxide with a small particle diameter independently have a nickel content of 70 mol % or more among all metals except lithium.
  9. 9 . A positive electrode comprising the positive electrode active material according to claim 1 .
  10. 10 . A lithium secondary battery comprising the positive electrode of claim 9 .

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2023/021400, which was filed on Dec. 22, 2023 and claims priority to Korean Patent Application No. 10-2022-0184962, filed on Dec. 26, 2022, all of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a positive electrode active material for a lithium secondary battery, and a positive electrode and a lithium secondary battery including the same. BACKGROUND A lithium secondary battery is generally composed of a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode and the negative electrode include an active material capable of intercalating and deintercalating lithium ions. As a positive electrode active material for the lithium secondary battery, a lithium cobalt oxide (LiCoO2), a lithium nickel oxide (LiNiO2), a lithium manganese oxide (LiMnO2, LiMnO4, or the like), a lithium iron phosphate compound (LiFePO4), etc. have been used. Among them, the lithium cobalt oxide has the advantages of high operating voltage and excellent capacity characteristics, but the price of cobalt, which is a raw material, is high and its supply is unstable, making it difficult to commercially apply it to a large-capacity battery. The lithium nickel oxide has poor structural stability, making it difficult to achieve sufficient lifespan characteristics. Meanwhile, the lithium manganese oxide has excellent stability, but has a problem of poor capacity characteristics. Therefore, in order to compensate for the problems of the lithium transition metal oxides containing Ni, Co, or Mn alone, lithium nickel-based transition metal oxides containing two or more transition metals have been developed, and in particular, a lithium nickel cobalt manganese oxide containing Ni, Co, and Mn are widely used in the field of electric vehicle batteries. Conventional lithium nickel cobalt manganese oxide was generally in the form of a spherical secondary particle in which tens to hundreds of primary particles are aggregated. However, in the case of the lithium nickel cobalt manganese oxide in the form of a secondary particle in which a large number of primary particles are aggregated, there is a problem in that particle breakage, in which primary particles fall off, is likely to occur during the rolling process when manufacturing a positive electrode, and cracks occur inside the particles during the charging and discharging process. When the particle breakage or cracks of the positive electrode active material are generated, the contact area with an electrolyte increases, which increases generation of gas and deterioration of the active material due to side reactions with the electrolyte, thereby degrading lifespan characteristics. SUMMARY Technical Problem The present disclosure is intended to solve the above problems and provide a positive electrode active material that can suppress particle breakage and cracks during the electrode manufacturing and charging/discharging process, and has excellent rolling density. In addition, the present disclosure is to provide a positive electrode and a lithium secondary battery which include the above positive electrode active material, thereby having a low crack rate and thus reduced side reactions with an electrolyte, which lead to improved high temperature lifespan, output, and high temperature storage characteristics. Technical Solution In order to solve the above problems, according to one aspect of the present disclosure, there is provided a positive electrode active material including: a lithium nickel-based transition metal oxide with a large particle diameter and a lithium nickel-based transition metal oxide with a small particle diameter, wherein the lithium nickel-based transition metal oxide with a large particle diameter is in the form of a secondary particle that is an aggregate of primary particles, and the lithium nickel-based transition metal oxide with a small particle diameter is in the form of at least one of a single particle formed of one nodule and a quasi-single particle that is a composite of 30 or less nodules, and wherein the lithium nickel-based transition metal oxide with a large particle diameter has a D50 of 5 μm to 30 μm, and a Y value defined by the following Equation 1 of 2.2 or less: Y=ImaxD/(DFWHM×RL)[Equation⁢ 1]wherein the IDmax and DFWHM are values obtained from a volume cumulative particle size distribution graph obtained from particle size analysis (PSD) of the lithium nickel-based transition metal oxide with a large particle diameter, wherein the DFWHM is a full width at half maximum (FWHM) of a peak, and IDmax is a maximum value of a peak; and the RL refers to a weight ratio of the lithium nickel-based transition metal oxide with a large particle diameter among the total positive electrode active material, and is a rational number great