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CN-122003739-A - Positive electrode active material and method for preparing positive electrode active material

CN122003739ACN 122003739 ACN122003739 ACN 122003739ACN-122003739-A

Abstract

The present invention relates to a positive electrode active material comprising a single-particle type lithium transition metal oxide having a nickel content of 80 mol% or more in metals other than lithium and composed of 1 to 30 nodules, wherein a cation mixing rate satisfies a specific mathematical formula, a method for producing a positive electrode active material comprising a first step of mixing a transition metal precursor oxide having a nickel content of 80 mol% or more in all metals with an anhydrous lithium raw material to produce a mixture, and a second step of firing the mixture to produce a single-particle type lithium transition metal oxide composed of 1 to 30 nodules, wherein a ratio of D 50 of the anhydrous lithium raw material to D 50 of the transition metal precursor oxide is 4 to 20.

Inventors

  • YU JUNYU
  • JIN ZHIHUI
  • Xu Zongxu
  • Zheng Meiji
  • Yin Zhaoyong
  • Pu Bingtian

Assignees

  • 株式会社LG新能源

Dates

Publication Date
20260508
Application Date
20241105
Priority Date
20231108

Claims (15)

  1. 1. A positive electrode active material comprising a single-particle lithium transition metal oxide having a nickel content of 80 mol% or more in a metal other than lithium and consisting of 1 to 30 nodules, wherein a cation mix rate (P) of the positive electrode active material satisfies the following mathematical formula 1: [ mathematics 1] Wherein, in the above formula 1, P is the positive ion miscibility value of the positive electrode active material, and X is the value of the nickel content in the metal other than lithium of the lithium transition metal oxide, Wherein the cation mixing rate is measured in atomic percent, the nickel content is measured in mol percent, but P and X are the number of units without units, and S is the value obtained by multiplying the crystal strain by 10 6 .
  2. 2. The positive electrode active material according to claim 1, wherein D 50 of the positive electrode active material is 3.0 μm to 6.0 μm.
  3. 3. The positive electrode active material according to claim 1, wherein the lithium transition metal oxide has a composition of the following chemical formula 1: [ chemical formula 1] Li 1+x (Ni a Co b M 1 c M 2 d )O 2 Wherein, in the above chemical formula 1, M 1 is Mn, al or a combination thereof, M 2 is one or more selected from the group consisting of W, cu, fe, V, cr, ti, zr, zn, in, ta, Y, la, sr, ga, sc, gd, sm, ca, ce, nb, mg, B and Mo, and 0≤x≤0.50,0.80≤a≤1,0≤b≤0.20,0≤c≤0.20,0≤d≤0.10,a+b+c+d=1。
  4. 4. The positive electrode active material according to claim 1, wherein the positive electrode active material has a cation mixing rate of 2.0 at% or less.
  5. 5. The positive electrode active material according to claim 1, wherein when the positive electrode active material is pressurized with a force of 12 tons, a generation rate of fine particles having a particle diameter of 1 μm or less is 2.0% by volume or less with respect to a total volume of the positive electrode active material.
  6. 6. The positive electrode active material according to claim 1, wherein the positive electrode active material has a single particle size of 3.0 to 4.5 according to the following formula 2: [ math figure 2] Wherein, in the above-mentioned formula 2, R i is a radius value of an ith grain measured by ion milling an electrode fabricated using the positive active material and then analyzing the electrode by Electron Back Scattering Diffraction (EBSD), Wherein the radius of the crystal grain is measured in μm, but R i is the number of units free without units, and n is the total number of crystal grains measured by EBSD analysis, and is 350 to 450.
  7. 7. The positive electrode active material according to claim 1, wherein the positive electrode active material contains LiOH and Li 2 CO 3 on the surface of particles, and the total weight of LiOH and Li 2 CO 3 is 0.50 wt% or less based on the total weight of the positive electrode active material.
  8. 8. A method of preparing a positive electrode active material, the method comprising: A first step of mixing a transition metal precursor oxide having a nickel content of 80 mol% or more in the whole metal with an anhydrous lithium raw material to prepare a mixture, and A second step of firing the mixture to prepare a single-particle lithium transition metal oxide composed of 1 to 30 nodules, Wherein the ratio of D 50 of the anhydrous lithium starting material to D 50 of the transition metal precursor oxide is 4 to 20.
  9. 9. The method of claim 8, wherein the transition metal precursor oxide has a composition of the following chemical formula 2: [ chemical formula 2] Ni a1 Co b1 M 1 c1 M 2 d1 O Wherein, in the above chemical formula 2, M 1 is Mn, al or a combination thereof, M 2 is one or more selected from the group consisting of W, cu, fe, V, cr, ti, zr, zn, in, ta, Y, la, sr, ga, sc, gd, sm, ca, ce, nb, mg, B and Mo, and 0.80≤a1≤1,0≤b1≤0.20,0≤c1≤0.20,0≤d1≤0.10,a1+b1+c1+d1=1。
  10. 10. The method of claim 8, wherein the transition metal precursor oxide has a D 50 of 3 μιη to 6 μιη.
  11. 11. The method of claim 8, wherein the anhydrous lithium feedstock has a D 50 of 12 μιη to 60 μιη.
  12. 12. The method of claim 8, wherein firing of the second step is performed at 650 ℃ to 900 ℃.
  13. 13. The method according to claim 8, wherein the loss rate of the raw material according to the following equation 3 is 5 wt% or less: [ math 3] [1- { Weight of lithium transition metal oxide prepared/(weight of transition metal precursor oxide charged+weight of anhydrous lithium raw material charged) } ]. Times.100 (%).
  14. 14. A positive electrode comprising the positive electrode active material according to claim 1.
  15. 15. A lithium secondary battery, comprising: The positive electrode according to claim 14, a negative electrode comprising a negative electrode active material, a separator sandwiched between the positive electrode and the negative electrode, and an electrolyte.

Description

Positive electrode active material and method for preparing positive electrode active material Technical Field The present application claims priority from korean patent application No. 10-2023-0154027 filed on 8 th 11 of 2023 and korean patent application No. 10-2024-0154763 filed on 4 th 11 of 2024, the disclosures of which are incorporated herein in their entireties. The present invention relates to a positive electrode active material in which the orientation of primary particles is controlled, a method for preparing the same, and a positive electrode and a lithium secondary battery including the positive electrode active material. Background In recent years, due to rapid popularization of electronic devices using batteries, such as mobile phones, notebook computers, and electric vehicles, there has been a rapid increase in demand for small-sized and lightweight secondary batteries having relatively high capacities. In particular, lithium secondary batteries are lightweight and have high energy density, and thus are attracting attention as driving power sources for portable devices. Accordingly, research and development work for improving the performance of lithium secondary batteries has been actively conducted. When an organic electrolyte or a polymer electrolyte between a positive electrode and a negative electrode made of an active material capable of intercalating and deintercalating lithium ions is charged, the lithium secondary battery generates electric energy through oxidation-reduction reaction of intercalation/deintercalation of lithium ions at the positive electrode and the negative electrode. As a positive electrode active material of a lithium secondary battery, lithium cobalt oxide (LiCoO 2), lithium nickel oxide (LiNiO 2), lithium manganese oxide (LiMnO 2, liMn 2O4, or the like), lithium iron phosphate compound (LiFePO 4), or the like has been mainly used. Meanwhile, as a method of improving the thermal stability of LiNiO 2 having a low thermal stability while maintaining its excellent reversible capacity, a lithium composite metal oxide (hereinafter, referred to as "NCM oxide") in which a part of nickel is replaced with cobalt and manganese has been developed. However, the capacity characteristics of the conventional NCM oxide that has been developed are insufficient, so that there is a limitation in its application. In order to overcome the above limitations, in recent years, studies have been made to increase the Ni content in NCM oxide. However, the high Ni positive electrode active material having a high nickel content has problems in that a large amount of gas is generated during charge and discharge due to high reactivity of nickel, and the lattice structure is extremely unstable and the content of lithium impurities remaining on the surface increases due to cation mixing and oxygen deintercalation. Therefore, there is a need to develop a positive electrode material containing a high content of nickel so as to have excellent capacity while ensuring structural stability. Disclosure of Invention Technical problem The present invention aims to provide a high nickel positive electrode active material in a single particle form, which controls crystal strain and cation mixing rate under predetermined conditions, and a method for preparing the positive electrode active material. Technical proposal [1] The present invention provides a positive electrode active material comprising a single-particle lithium transition metal oxide having a nickel content of 80 mol% or more in a metal other than lithium and consisting of 1 to 30 nodules, wherein a cation mixing rate (P) of the positive electrode active material satisfies the following mathematical formula 1. [ Mathematics 1] In the above formula 1, P is a cation mixed rate value of the positive electrode active material, X is a value of nickel content in a metal other than lithium of the lithium transition metal oxide, wherein the cation mixed rate is measured in atomic%, and the nickel content is measured in mol%, but P and X are both unitless numbers without units, and S is a value obtained by multiplying a crystal strain by 10 6. [2] In the above [1], the present invention provides a positive electrode active material, wherein D 50 of the positive electrode active material is 3.0 μm to 6.0 μm. [3] In the above [1] or [2], the present invention provides a positive electrode active material, wherein the lithium transition metal oxide has a composition of the following chemical formula 1. [ Chemical formula 1] Li1+x(NiaCobM1cM2d)O2 In the above chemical formula 1, M 1 is Mn, al, or a combination thereof, M 2 is one or more selected from the group consisting of W, cu, fe, V, cr, ti, zr, zn, in, ta, Y, la, sr, ga, sc, gd, sm, ca, ce, nb, mg, B and Mo, and 0≤x≤ 0.50,0.80≤a≤1, 0≤b≤0.20, 0≤c≤0.20, 0≤d≤0.10, a+b+c+d=1. [4] In the above [1] to [3], the present invention provides a positive electrode active material, wherein the positive electrode ac