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EP-4737396-A1 - METHOD FOR PREPARING POSITIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY COMPRISING POSITIVE ELECTRODE ACTIVE MATERIAL PREPARED THEREBY

EP4737396A1EP 4737396 A1EP4737396 A1EP 4737396A1EP-4737396-A1

Abstract

The present embodiments relate to a method for preparing a positive electrode active material for a lithium secondary battery and a lithium secondary battery comprising the same. A method for preparing a positive electrode active material for a lithium secondary battery according to one embodiment includes: preparing a metal hydroxide comprising nickel, cobalt, and manganese; mixing the metal hydroxide with a lithium raw material and dopant raw materials to prepare a mixture; pre-calcining the mixture to obtain a pre-calcined product; calcining the pre-calcined product in a two-step process comprising a first-step calcination and a second-step calcination to obtain a calcined material in a single-particle form; and mixing the calcined material with coating raw materials and heat-treating the mixture to obtain a metal oxide having a coating layer formed thereon, wherein, in the step of obtaining the calcined material, the first-step calcination may be performed at a temperature of 870°C to 915°C for 2 hours to 6 hours.

Inventors

  • MYUNG, Minhoon
  • LEE, SUBIN
  • LEE, Byong June
  • SIM, Sung Keun
  • LEE, SEUNGWON
  • CHOI, KWONYOUNG

Assignees

  • Posco Future M Co., Ltd.

Dates

Publication Date
20260506
Application Date
20240626

Claims (17)

  1. A method for preparing a positive electrode active material for a lithium secondary battery, comprising: preparing a metal hydroxide comprising nickel, cobalt, and manganese; mixing the metal hydroxide with a lithium raw material and dopant raw materials to prepare a mixture; pre-calcining the mixture to obtain a pre-calcined product; calcining the pre-calcined product in a two-step process comprising a first-step calcination and a second-step calcination to obtain a calcined material in a single-particle form; and mixing the calcined material with coating raw materials and heat-treating the mixture to obtain a metal oxide having a coating layer formed thereon, wherein, in the step of obtaining the calcined material, the first-step calcination is performed at a temperature of 870°C to 915°C for 2 hours to 6 hours hours.
  2. The method of claim 1, wherein the pre-calcination is performed at a temperature of 650°C to 770°C for 3 hours to 10 hours.
  3. The method of claim 1, wherein the second-step calcination is performed at a temperature of 750°C to 870°C for 5 hours to 14 hours.
  4. The method of claim 1, wherein, in the step of preparing the mixture, the dopant raw materials comprise an Al raw material, a Y raw material, and a Zr raw material.
  5. The method of claim 4, wherein the Al raw material is mixed in an amount of 500 ppm to 1000 ppm based on the metal hydroxide.
  6. The method of claim 4, wherein the Y raw material is mixed in an amount of 500 ppm to 1200 ppm based on the metal hydroxide.
  7. The method of claim 4, wherein the Zr raw material is mixed in an amount of 500 ppm to 2000 ppm based on the metal hydroxide.
  8. The method of claim 1, wherein the coating raw materials comprise a Co coating raw material and an Al coating raw material.
  9. The method of claim 8, wherein the Co coating raw material is mixed in an amount of 1.5 mol% to 3 mol% based on the calcined material.
  10. The method of claim 8, wherein the Al coating raw material is mixed in an amount of 500 ppm to 1500 ppm based on the calcined material.
  11. The method of claim 1, wherein the heat treatment for obtaining the metal oxide having the coating layer is performed at a temperature of 660°C to 760°C for 3 hours to 8 hours.
  12. The method of claim 1, wherein, in the step of obtaining the calcined material, a charge amount of the pre-calcined product loaded into the calcination furnace is 4 kg or more.
  13. A positive electrode active material for a lithium secondary battery, comprising: a nickel-containing metal oxide in a single-particle form; and a coating layer disposed on a surface of the nickel-containing metal oxide, wherein the nickel-containing metal oxide comprises at least three kinds of dopant elements, and wherein, when the metal oxide having the coating layer is magnified 5000 times and measured in a SEM image having a size of 2.5 cm × 1.0 cm, the number of non-grown particles is two or fewer.
  14. The positive electrode active material of claim 13, wherein a ratio of lithium hydroxide to lithium carbonate among the residual lithium on the surface of the positive electrode active material (LiOH/Li 2 CO 3 ) is in a range of 1.0 to 2.0.
  15. The positive electrode active material of claim 13, wherein, when the positive electrode active material is pressed five times using a roll press at a press gauge of 0.01 mm, the total amount of fine particles having a particle size of less than 1 µm is 2.5 vol% or less.
  16. A positive electrode for a lithium secondary battery comprising the positive electrode active material prepared according to any one of claims 1 to 12.
  17. A lithium secondary battery comprising the positive electrode of claim 16.

Description

[Technical Field] The present embodiments relate to a method for manufacturing a positive electrode active material for a lithium secondary battery and to a lithium secondary battery comprising a positive electrode active material manufactured by the method. [Background Art] In recent years, driven by the explosive demand for electric vehicles and the need for extended driving ranges, the development of secondary batteries having high capacity and high energy density has been actively pursued worldwide. In particular, high-nickel NCM positive electrode materials having a high nickel content have been used to satisfy such demands. However, as the nickel content increases, particle strength deteriorates, resulting in the generation of microcracks during charge and discharge. In addition, such microcracks increase the specific surface area of the positive electrode material, and accordingly, increase reactions with the electrolyte, which leads to increased gas generation. Furthermore, due to structural instability, unstable Ni3+ is reduced to stable Ni2+ and is converted into stable NiO, thereby increasing cation mixing. Thus, it is difficult to practically apply such materials as positive electrode active materials for lithium-ion batteries for use in electric vehicles or energy storage. To address these issues, an approach has been proposed in which a positive electrode material is prepared in a single-particle form by maximizing the size of primary particles, instead of using a multiparticle form in which primary particles are aggregated into secondary particles. However, to manufacture a positive electrode material in a single-particle form, calcination must be performed at a higher temperature compared to multiparticle materials, and during such calcination, under-sintering commonly occurs, resulting in defects in the layered crystal structure and deterioration of electrochemical characteristics such as capacity and output. In addition, when the calcination temperature is lowered to address this issue, the crystal grain size within the single particle does not sufficiently grow, resulting in deterioration of particle strength and lifespan characteristics. Moreover, to apply such a single-particle positive electrode material to industrial production, productivity improvement is also required. [Detailed Description of the Invention] [Technical Problem] The present embodiments are directed to providing a method for manufacturing a positive electrode active material for a lithium secondary battery that exhibits excellent electrochemical characteristics while also achieving improved productivity, and to providing a lithium secondary battery comprising the same. [Technical Solution] A method for manufacturing a positive electrode active material for a lithium secondary battery according to one embodiment includes: preparing a metal hydroxide comprising nickel, cobalt, and manganese; mixing the metal hydroxide with a lithium raw material and dopant raw materials to prepare a mixture; pre-calcining the mixture to obtain a pre-calcined product; calcining the pre-calcined product in a two-step process comprising a first-step calcination and a second-step calcination to obtain a calcined material in a single-particle form; and mixing the calcined material with coating raw materials and heat-treating the mixture to obtain a metal oxide having a coating layer formed thereon, wherein, in the step of obtaining the calcined material, the first-step calcination may be performed at a temperature of 870°C to 915°C for 2 hours to 6 hours. A positive electrode active material for a lithium secondary battery according to another embodiment includes a nickel-containing metal oxide in a single-particle form; and a coating layer disposed on a surface of the nickel-containing metal oxide, wherein the nickel-containing metal oxide comprises at least three kinds of dopant elements, and wherein, for the metal oxide having the coating layer, the number of non-grown particles measured in a SEM image at 5000× magnification and having a size of 2.5 cm × 1.0 cm may be two or fewer. A lithium secondary battery according to yet another embodiment may include a positive electrode comprising the positive electrode active material for a lithium secondary battery according to the aforementioned embodiment. [Effects of the Invention] According to the present embodiments, by performing a pre-calcination before the main calcination and performing the main calcination in a one-step process comprising a first-step calcination and a second-step calcination, it is possible to provide a method for manufacturing a positive electrode active material for a lithium secondary battery that exhibits excellent electrochemical characteristics while also achieving improved productivity. [Brief Description of the Drawings] FIG. 1 is a SEM image of the positive electrode active material manufactured according to Example 1 at 5000× magnification.FIG. 2 is a SEM ima