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EP-4738457-A1 - CATHODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY. AND LITHIUM SECONDARY BATTERY COMPRISING SAME

EP4738457A1EP 4738457 A1EP4738457 A1EP 4738457A1EP-4738457-A1

Abstract

The present embodiments relate to a positive electrode active material for a lithium secondary battery and a lithium secondary battery comprising the same. The positive electrode active material for a lithium secondary battery according to one embodiment includes a nickel-containing metal oxide in a single-particle form; dopant elements doped into the nickel-containing metal oxide; and a coating layer disposed on a surface of the nickel-containing metal oxide, wherein the dopant elements comprise three or more kinds, and the coating layer may comprise two or more coating elements.

Inventors

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

Assignees

  • Posco Future M Co., Ltd.

Dates

Publication Date
20260506
Application Date
20240626

Claims (17)

  1. A positive electrode active material for a lithium secondary battery, comprising: a nickel-containing metal oxide in a single-particle form; dopant elements doped into the nickel-containing metal oxide; and a coating layer disposed on a surface of the nickel-containing metal oxide, wherein the dopant elements comprise three or more kinds, and wherein the coating layer comprises two or more coating elements.
  2. The positive electrode active material of claim 1, wherein the coating layer comprises Co and Al.
  3. The positive electrode active material of claim 2, wherein an amount of Co in the positive electrode active material having the coating layer is from 0.035 mol to 0.08 mol based on a total of 1 mol of transition metals included in the nickel-containing metal oxide having the coating layer.
  4. The positive electrode active material of claim 2, wherein the dopant elements comprise Al, Y, and Zr.
  5. The positive electrode active material of claim 4, wherein an amount of Al in the positive electrode active material having the coating layer is from 0.001 mol to 0.015 mol based on a total of 1 mol of transition metals included in the nickel-containing metal oxide having the coating layer.
  6. The positive electrode active material of claim 4, wherein an amount of Y is from 400 ppm to 2,000 ppm based on a total weight of the nickel-containing metal oxide having the coating layer.
  7. The positive electrode active material of claim 4, wherein an amount of Zr is from 1,200 ppm to 2,800 ppm based on a total weight of the nickel-containing metal oxide having the coating layer.
  8. The positive electrode active material of claim 1, wherein an amount of nickel is 0.8 mol or more based on a total of 1 mol of transition metals included in the nickel-containing metal oxide having the coating layer.
  9. The positive electrode active material of claim 8, wherein the nickel-containing metal oxide further comprises manganese, and wherein an amount of the manganese is 0.15 mol or less based on a total of 1 mol of transition metals included in the nickel-containing metal oxide having the coating layer.
  10. The positive electrode active material of claim 1, wherein the nickel-containing metal oxide having the coating layer is represented by Formula 1 below: [Formula 1] Li a [Ni x Co γ Mn z M 1w 1 M 2w 2 ]O 2 wherein 0.8 ≤ a ≤ 1.2, 0.8 ≤ x ≤ 0.99, 0 < y ≤ 0.06, 0 < z ≤ 0.14, 0 < w 1 ≤ 0.1, 0 ≤ w 2 ≤ 0.1, and x + y + z + w 1 + w 2 = 1; wherein M 1 comprises Al, Y, and Zr; and wherein M 2 comprises one or more selected from B, Al, Mg, Ti, Nb, W, Sc, Si, V, Fe, Y, Mo, Ce, Hf, Ta, La, and Sr.
  11. The positive electrode active material of claim 1, wherein the positive electrode active material has a moisture increase rate of 80% or less at a temperature of 25 ± 3°C and a relative humidity of 50 ± 15%.
  12. The positive electrode active material of claim 1, wherein the positive electrode active material has a residual-lithium increase rate of 20% or less at a temperature of 25 ± 3°C and a relative humidity of 50 ± 15%.
  13. The positive electrode active material of claim 1, wherein the positive electrode active material having the coating layer has a residual-lithium reduction rate of 55% or more relative to the doped nickel-containing metal oxide.
  14. The positive electrode active material of claim 1, wherein an average particle diameter (D50) of the positive electrode active material is 3 µm or more.
  15. The positive electrode active material of claim 1, wherein a crystal grain size of the nickel-containing metal oxide having the coating layer is 200 nm or more.
  16. A positive electrode for a lithium secondary battery comprising the positive electrode active material of any one of claims 1 to 15.
  17. A lithium secondary battery comprising the positive electrode of claim 16.

Description

[Technical Field] The present embodiments relate to a positive electrode active material for a lithium secondary battery and a lithium secondary battery comprising the same. [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, which contain a high nickel content, have been utilized to meet such demands. However, as the nickel content increases, the particle strength deteriorates, resulting in the generation of microcracks during charge and discharge. In addition, due to such microcracks, the specific surface area of the positive electrode material increases, thereby accelerating reactions with the electrolyte and causing an increase in gas generation. Moreover, due to structural instability, unstable Ni3+ is reduced to stable Ni2+ and is further converted into stable NiO, thereby increasing cation mixing. Accordingly, 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, rather than utilizing a multi-particle structure in which primary particles are aggregated into secondary particles. However, in general, manufacturing a positive electrode material in a single-particle form requires calcination at a higher temperature than that used for multi-particle structures, and in this process, under-sintering or over-sintering commonly occurs, resulting in layered-structure crystal defects that degrade electrochemical properties such as capacity and output. Moreover, when the calcination temperature is lowered to prevent such issues, the crystal grain size within a single particle does not grow sufficiently, leading to deterioration in particle strength and lifespan characteristics. [Detailed Description of the Invention] [Technical Problem] The present embodiments are directed to providing a positive electrode active material for a lithium secondary battery, and a lithium secondary battery including the same, which exhibit excellent electrochemical characteristics and improved lifespan and resistance properties. [Technical Solution] A positive electrode active material for a lithium secondary battery according to one embodiment includes a nickel-containing metal oxide in a single-particle form; dopant elements doped into the nickel-containing metal oxide; and a coating layer disposed on a surface of the nickel-containing metal oxide, wherein the dopant elements comprise three or more kinds, and the coating layer may comprise two or more coating elements. In another embodiment, a lithium secondary battery 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 including at least three kinds of dopant elements in the nickel-containing metal oxide in a single-particle form and including a coating layer disposed on the surface of the nickel-containing metal oxide and comprising at least two kinds of coating elements, it is possible to stabilize the crystal structure and simultaneously improve particle strength. Accordingly, the present embodiments enable the realization of a positive electrode active material that is in a single-particle form while exhibiting excellent electrochemical characteristics as well as improved lifespan and resistance properties. In addition, when the positive electrode active material according to the present embodiments is applied, an electrode of superior quality can be manufactured. [Best Mode for Carrying Out the Invention] The 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 only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Thus, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention. The terminology used herein is intended only to describe particular embodiments and is not intended to limit the present invention. The singular forms used herein include plural forms as well unless the context clearly indicates otherwise. The term "comprising/including/containing" as used in the specification, specifies the presence of stated features, regions, integers, steps, operations, elements, and/or components but does not preclude the presence or addition of one