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EP-4742320-A1 - POSITIVE ELECTRODE ACTIVE MATERIAL COMPOSITE, POSITIVE ELECTRODE COMPRISING SAME, AND LITHIUM-ION SECONDARY BATTERY COMPRISING POSITIVE ELECTRODE

EP4742320A1EP 4742320 A1EP4742320 A1EP 4742320A1EP-4742320-A1

Abstract

The present invention provides a positive electrode active material composite comprising a positive electrode active material substrate and a coating layer coated on the positive electrode active material substrate, wherein the coating layer comprises a coating substrate comprising Li, Ta, Ti, and O, wherein each element in the coating layer has a molar ratio of 3.5≤Li≤4.5, 4.5≤Ti≤5.4, 10<O≤15, and 0.1≤Ta≤0.5, a positive electrode comprising same, and a lithium-ion secondary battery comprising the positive electrode.

Inventors

  • KIM, MYEONGSOO
  • KWON, Hyejin
  • KANG, Sora

Assignees

  • LG Energy Solution, Ltd.

Dates

Publication Date
20260513
Application Date
20240816

Claims (12)

  1. A positive electrode active material composite comprising a positive electrode active material substrate and a coating layer coated on the positive electrode active material substrate, wherein the coating layer includes a coating substrate comprising Li, Ta, Ti, and O, wherein each element in the coating substrate has a molar ratio of 3.5≤Li≤4.5, 4.5≤Ti≤5.4, 10<O≤15, and 0.1≤Ta≤0.5.
  2. The positive electrode active material composite according to claim 1, wherein the coating substrate is lithium titanium oxide (LTO) to which tantalum (Ta) is added, or it is a compound represented by Formula 1. [Formula 1] Li a Ta x Ti b-x O c wherein 3.5≤a≤4.5, 5≤b≤5.5, 10<c≤15, and 0.1≤x≤0.5.
  3. The positive electrode active material composite according to claim 1, wherein the coating substrate is a compound represented by Formula 1, wherein a is 4, b is 5, c is 12, and x is at least 0.1 and less than 0.5.
  4. The positive electrode active material composite according to claim 1, wherein the positive electrode active material substrate is a compound represented by Formula 2. [Formula 2] Li a (Ni 1-x-y-z CO x M1 y M2 z )O 2 wherein M1 is manganese (Mn), aluminum (Al), or a combination thereof; M2 is boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zirconium (Zr), aluminum (Al), or any combination of two or more thereof; and 0.95≤a≤1.3, 0<x<1, 0≤y<1, and 0≤z<1.
  5. The positive electrode active material composite according to claim 1, wherein the coating layer is comprised in an amount of at least 0.05% by weight and less than 5% by weight based on the total weight of the positive electrode active material composite.
  6. The positive electrode active material composite according to claim 1, wherein the coating layer has a thickness of 10 nm to 200 nm.
  7. The positive electrode active material composite according to claim 1, wherein the molar ratio of Ti and Ta in the coating layer is 1 : 0.06 to 0.11.
  8. A positive electrode comprising the positive electrode active material composite according to claim 1.
  9. The positive electrode according to claim 8, which further contains a sulfide-based solid electrolyte.
  10. The positive electrode according to claim 9, wherein the sulfide-based solid electrolyte is a compound represented by Formula 3. [Formula 3] Li x M' y PS z A w wherein x, y, z, and w are independently between 0 to 6, inclusive; M' is at least one of As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta; and A is at least one of F, Cl, Br, or I.
  11. A lithium-ion secondary battery comprising a positive electrode according to claim 8, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and negative electrode.
  12. The lithium-ion secondary battery according to claim 11, wherein the lithium-ion secondary battery is a sulfide-based all-solid-state battery.

Description

[Technical Field] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0106852, filed August 16, 2023, and Korean Patent Application No. 10-2024-0109428, filed August 14, 2024, the disclosures of which are incorporated herein by reference in their entirety. The present invention relates to a positive electrode active material composite, a positive electrode comprising the same, and a lithium-ion secondary battery comprising the positive electrode. [Related Art] Compared to nickel-manganese or nickel-cadmium batteries, lithium-ion secondary batteries have the advantages of higher energy density, lower self-discharge rate, and longer lifetime, but their disadvantages include stability issues against overheating and low power output. To overcome the problems of lithium-ion secondary batteries, all-solid-state batteries have been proposed as an alternative. The all-solid-state battery comprises an electrolyte layer comprising a solid electrolyte, and a positive electrode layer and a negative electrode layer comprising the solid electrolyte are formed on both sides of the electrolyte layer, and each electrode has a structure in which a current collector is coupled. The all-solid-state batteries can be divided into oxide-based, polymer-based, and sulfide-based batteries according to the raw material of the solid electrolyte. The sulfide-based all-solid-state batteries exhibit superior lithium-ion conductivity to other types of batteries. Nevertheless, compared to conventional liquid electrolyte-based batteries, they suffer from low ionic conductivity and high electrical resistance between the positive electrode/negative electrode/solid electrolyte, which reduces their lifespan and power output. In other words, the positive electrode active material and the sulfide-based solid electrolyte are known to react with each other at the interface to form a resistive material that interferes with the operation of the all-solid-state battery. The resistive material reduces the initial capacity of the all-solid-state battery and its efficiency. To address these issues, techniques are known to form various coating layers on the surface of the positive electrode active material. For example, there are known techniques for coating lithium oxides of Li-M-O (wherein M is B, Al, Zr, P, Ti, Nb, W, etc.) on the surface of positive electrode active materials. However, this type of coated positive electrode active material does not appear to be effective enough in reducing the interfacial resistance between the positive electrode active material and the sulfide-based solid electrolyte and improving lithium ion conductivity. [Prior Art Reference] [Patent Reference] Korean Laid-open Patent Publication No. 10-2018-0123369 [Detailed Description of the Invention] [Technical Problem] The present invention is designed to solve the above problems of the prior art, it is an object to provide a positive electrode active material composite, which can improve the drive characteristics and life characteristics of the battery by reducing the interfacial resistance between the positive electrode active material and the solid electrolyte, and by improving the lithium-ion conductivity, a positive electrode comprising the positive electrode active material composite, and a lithium-ion secondary battery comprising the positive electrode. [Technical Solution] To accomplish the above objectives, the present invention provides a positive electrode active material composite comprising a positive electrode active material substrate and a coating layer coated on the positive electrode active material substrate, wherein the coating layer includes a coating substrate comprising Li, Ta, Ti, and O,wherein each element in the coating substrate has a molar ratio of 3.5≤Li≤4.5, 4.5≤Ti≤5.4, 10<O≤15, and 0.1≤Ta≤0.5. The present invention also provides a positive electrode comprising the positive electrode active material composite of the present invention. The present invention also provides a lithium-ion secondary battery comprising a positive electrode of the present invention, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and negative electrode. [Advantageous Effects] The positive electrode active material composite of the present invention provides the effect of reducing the interfacial resistance between the positive electrode active material and the solid electrolyte by a coating layer formed on the surface of the positive electrode active material and improving the lithium ion conductivity. Furthermore, it provides the effect of improving the drive characteristics and life characteristics of the battery by the above effects. By including the positive electrode active material, the lithium-ion secondary battery of the present invention provides excellent drive characteristics and life characteristics. [Best Mode] Hereinafter, the present invention will be described in more detail