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EP-4738461-A1 - POSITIVE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY, PREPARATION METHOD THEREFOR, POSITIVE ELECTRODE COMPRISING SAME, AND LITHIUM SECONDARY BATTERY

EP4738461A1EP 4738461 A1EP4738461 A1EP 4738461A1EP-4738461-A1

Abstract

According to an embodiment of the present disclosure, there is provided a positive electrode active material for lithium secondary battery comprising: a lithium compound represented by the following Chemical Formula 1, and a coating layer formed on the surface of particles of the lithium compound. wherein the coating layer includes a carbon and a surface modifier, and wherein the positive electrode active material has a D/G band ratio value of 0.7 to 0.89 when its surface is measured by Raman spectroscopy. [Chemical Formula 1]     Li 1+a Ti b Mn c O 2-d X d in Chemical Formula 1, 0.1≤a≤0.5, 0.2≤b≤0.6, 0.2≤c≤0.6, 1.1≤(1+a)/(b+c)≤1.5, 0≤d≤0.2, and X is a halogen element, a method for preparing the same, a positive electrode and a lithium secondary battery including the same.

Inventors

  • KIM, DONG HWI
  • JEON, HYELIM
  • SHIN, Seungsun
  • RYU, Kihoon
  • Jang, Joonhyuk

Assignees

  • LG Energy Solution, Ltd.

Dates

Publication Date
20260506
Application Date
20241129

Claims (14)

  1. A positive electrode active material for lithium secondary battery comprising: a lithium compound represented by the following Chemical Formula 1, and a coating layer formed on the surface of particles of the lithium compound. wherein the coating layer includes a carbon and a surface modifier, and wherein the positive electrode active material has a D/G band ratio value of 0.7 to 0.89 when its surface is measured by Raman spectroscopy. [Chemical Formula 1] Li 1+a Ti b Mn c O 2-d X d in Chemical Formula 1, 0.1 ≤ a ≤ 0.5 , 0.2 ≤ b ≤ 0.6 , 0.2 ≤ c ≤ 0.6 , 1.1 ≤ 1 + a / b + c ≤ 1.5 , 0 ≤ d ≤ 0.2 , and X is a halogen element.
  2. The positive electrode active material according to claim 1, wherein in Chemical Formula 1, b+c=0.8.
  3. The positive electrode active material according to claim 1, wherein the positive electrode active material has an average primary particle diameter(D50) of 10 to 100 nanometers and an average secondary particle diameter(D50) of 0.5 to 1.5 micrometers.
  4. The positive electrode active material according to claim 1, wherein the contents of the carbon and the surface modifier is 0.5 to 1.5 wt.% based on the total weight of the positive electrode active material, respectively.
  5. The positive electrode active material according to claim 1, wherein the total content of the carbon and the surface modifier is 1 to 3 wt.% based on the total weight of the positive electrode active material.
  6. The positive electrode active material according to claim 1, wherein the surface modifier is a nonionic surface modifier, which is at least one selected from the group consisting of polyvinylpyrrolidone(PVP) and polyvinyl chloride(PVC).
  7. A method for preparing the positive electrode active material for lithium secondary battery according to claim 1, which is prepared by a solid phase method based on a mixture containing an active material precursor, a carbon precursor, and a surface modifier.
  8. The method for preparing the positive electrode active material according to claim 7, wherein the active material precursor is a lithium source, a manganese source, and a titanium source.
  9. The method for preparing the positive electrode active material according to claim 7, wherein the carbon precursor is at least one selected from the group consisting of citric acid and sucrose.
  10. The method for preparing the positive electrode active material according to claim 7, wherein the surface modifier is a nonionic surface modifier, which is at least one selected from the group consisting of polyvinylpyrrolidone(PVP) and polyvinyl chloride(PVC).
  11. The method for preparing the positive electrode active material according to claim 7, wherein the solid phase method involves calcinating the mixture at 550°C to 1050°C in an inert atmosphere.
  12. A positive electrode in which a positive electrode mixture layer containing the positive electrode active material according to claim 1 is formed on one side or both sides of a positive electrode current collector.
  13. The positive electrode according to claim 12, wherein a ratio of the content of carbon to the content of carbon and metal (Ti and Mn) represented by the following Equation 1 in the positive electrode active material is 0.75 to 0.9. C content / C + Metal content
  14. A lithium secondary battery comprising the positive electrode according to claim 12.

Description

[TECHNICAL FIELD] Cross-Reference to Related Application(s) This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0169859, filed on November 29, 2023, and Korean Patent Application No. 10-2024-0173826, filed on November 28, 2024, with the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entirety. The present disclosure relates to a positive electrode active material for lithium secondary battery, a method for preparing the same, a positive electrode and a lithium secondary battery including the same. [BACKGROUND] Due to the rapid increase in the use of fossil fuels, the demand for the use of alternative energy or clean energy is increasing, and as a part thereof, the fields that are being studied most actively are the fields of power generation and power storage using electrochemistry. Currently, a secondary battery is a representative example of an electrochemical device that utilizes such electrochemical energy, and the range of use thereof tends to be gradually expanding. Recently, with the increase of the technological development and demand for mobile devices such as portable computers, portable phones, and cameras, demand for secondary batteries as an energy source rapidly increases. Among such secondary batteries, many studies have been conducted on a lithium secondary battery that exhibit high energy density and operating potential, have a long cycle life, and a low self-discharge rate, and has been commercialized and widely used. In addition, as interest in environmental issues grows, studies are frequently conducted on an electric vehicle, a hybrid electric vehicle, etc. which can replace a vehicle using fossil fuels such as a gasoline vehicle and a diesel vehicle, which are one of the main causes of air pollution. Although a nickel metal hydride secondary battery is mainly used as a power source for the electric vehicle and the hybrid electric vehicle, numerous studies have been actively made to use a lithium secondary battery having a high energy density and a high discharge voltage, a part of which are in the commercializing stage. A lithium secondary battery generally has a structure in which a non-aqueous electrolytic solution is impregnated into an electrode assembly including a positive electrode, a negative electrode and a porous separator. In general, the positive electrode is prepared by coating a positive electrode mixture containing a positive electrode active material onto an aluminum foil, and the negative electrode is prepared by coating a negative electrode mixture containing a negative electrode active material onto a copper foil. Usually, the positive electrode active material is a lithium transition metal oxide, and the negative electrode active material is a carbon-based material. Recently, however, as lithium secondary batteries are used in various industrial fields, high capacity and high rate characteristics are being studied as important performances, and thus, the positive electrode active materials capable of exhibiting such characteristics are being actively developed. The material that has recently been in the spotlight as such a positive electrode active material is DRX (cation-disordered rock salt transition metal oxide), and this material is a high-capacity material that can express further capacity through not only cation oxidation/reduction but also anion oxidation/reduction reactions (oxygen redox). However, such materials have problems such as gas emission during high-voltage operation of lithium secondary batteries and degradation of lifetime characteristics caused by increased resistance of the material itself, and thus, improvements thereto remain an issue. Therefore, there is an urgent need to develop technology that can solve these problems and achieve secondary battery performance such as high capacity, high rate, and excellent lifetime characteristics. [DETAILED DESCRIPTION OF THE INVENTION] [Technical Problem] It is an object of the present disclosure to provide a positive electrode active material for lithium secondary battery that can exhibit high capacity, high rate and excellent lifetime characteristics, and a method for preparing the same. It is another object of the present disclosure to provide a positive electrode including such a positive electrode active material and a lithium secondary battery including the same. [Technical Solution] According to an embodiment of the present disclosure, there is provided a positive electrode active material for lithium secondary battery comprising: a lithium compound represented by the following Chemical Formula 1, and a coating layer formed on the surface of particles of the lithium compound.wherein the coating layer includes a carbon and a surface modifier, andwherein the positive electrode active material has a D/G band ratio value of 0.7 to 0.89 when its surface is measured by Raman spectroscopy.         [Chem