Search

KR-20260063851-A - Positive electrode active material for secondary battery

KR20260063851AKR 20260063851 AKR20260063851 AKR 20260063851AKR-20260063851-A

Abstract

According to one embodiment of the present invention, the positive active material particle comprises a bulk region and a coating region, wherein the coating region comprises cobalt (Co), the coating region covers a portion of the surface of the bulk region, and the unit coating region refers to a closed coating region that is not connected to another coating region on the surface of the bulk region, wherein the positive active material particle comprises one or more unit coating regions, and when measuring a scanning electron microscope (SEM) image of the surface of the positive active material particle using Image J, the average length (S) of the hypotenuse, where the shortest side drawn from the surface of the bulk region on the side of the unit coating region is called the hypotenuse, may be 40 nm ≤ S ≤ 70 nm.

Inventors

  • 이슬기
  • 오성호
  • 배진호
  • 이동근
  • 신세희

Assignees

  • 주식회사 에코프로비엠

Dates

Publication Date
20260507
Application Date
20241031

Claims (10)

  1. Includes a bulk area; and a coating area; and The above coating region contains cobalt (Co), and The above coating area covers a portion of the surface of the bulk area, and When a unit coating region refers to a closed coating region on the surface of a bulk region that is not connected to other coating regions, the cathode active material particle comprises one or more unit coating regions, and When measuring a Scanning Electron Microscope (SEM) image of the surface of a positive electrode active material particle using Image J, where the shortest side drawn from the surface of the bulk region on the side of the unit coating region is called the hypotenuse, for the average length (S) of the hypotenuse, 40 nm ≤ S ≤ 70 nm, Cathode active material particles.
  2. In Article 1, When a right triangle is drawn with the above hypotenuse as the hypotenuse and the part touching the surface of the bulk area as the base, for the average length of the base (W) and the average length of the height (H) of the right triangle, 0.58 ≤ H / W ≤ 2.75, Cathode active material particles.
  3. In Article 2, 30nm ≤ W ≤ 60nm, Cathode active material particles.
  4. In Article 2, 20nm ≤ H ≤ 50nm, Cathode active material particles.
  5. In Article 1, In a scanning electron microscope (SEM) image of one surface of the above-mentioned positive electrode active material particle, the ratio of the coating area of the said coating region to the total area of the said surface is 50% to 98%, Cathode active material particles.
  6. In Article 1, The above coating region further comprises one or more selected from aluminum (Al), zirconium (Zr), boron (B), tungsten (W), yttrium (Y), and titanium (Ti). Cathode active material particles.
  7. In Article 1, The above bulk region is doped with one or more elements selected from cobalt (Co), zirconium (Zr), barium (Ba), strontium (Sr), aluminum (Al), and titanium (Ti), Cathode active material particles.
  8. In Article 1, The average particle size (D50) of the above positive active material particles is 2.0 μm to 6.0 μm, Cathode active material particles.
  9. In Article 1, The above-mentioned positive active material particle consists of a single particle, or Containing 2 to 8 aggregated single particles Cathode active material particles.
  10. Comprising positive electrode active material particles according to claim 1, Cathode active material.

Description

Positive electrode active material for secondary battery The present invention relates to positive electrode active material particles and a positive electrode active material for a secondary battery containing the same, and more specifically, to a positive electrode active material that significantly improves the stability, lifespan, and output performance of a secondary battery when applied by controlling the composition, coating method, and coating form of a coating material containing cobalt (Co) of a lithium composite oxide. With the advancement of portable mobile electronic devices such as smartphones, MP3 players, and tablet PCs, the demand for rechargeable batteries capable of storing electrical energy is increasing explosively. In particular, the demand for lithium-ion batteries is rising due to the emergence of electric vehicles, medium-to-large energy storage systems, and portable devices requiring high energy density. As a lithium composite oxide included in the cathode active material, the material that has recently been receiving the most attention is lithium nickel (manganese/aluminum) cobalt oxide Li(Ni x Co y( Mn/Al) z )O 2 (where x, y, and z are the atomic fractions of independent oxide composition elements, 0<x≤1, 0<y≤1, 0<z≤1, and 0<x+y+z≤1). This cathode active material has the advantage of producing a high capacity because it is used at high voltage compared to LiCoO 2 , which has been actively researched and used as a cathode active material, and has the advantage of a low cost because the Co content is relatively low. However, these lithium composite oxides undergo volume changes due to the intercalation and deintercalation of lithium ions during charging and discharging. There are problems such as the primary particles of the lithium composite oxide rapidly changing in volume during charging and discharging, cracks occurring in the secondary particles due to repeated charging and discharging, or the collapse of the crystal structure or phase transition of the crystal structure. To compensate for these drawbacks, the demand for high-nickel cathode active materials for secondary batteries, which have a high nickel (Ni) content relative to the total metal content excluding lithium (Li), has begun to increase. However, high-nickel cathode active materials have the disadvantage of reduced lifespan due to poor stability caused by the high Ni content. In addition, due to the high Li/M ratio during manufacturing, the residual lithium content after calcination is high, making cell manufacturing difficult due to gelation during the preparation of the electrode slurry. Accordingly, a washing process is introduced to remove residual lithium, but there is a problem in that the cathode surface is damaged during the washing process, resulting in reduced battery performance. In addition, due to the high Ni content, the structure becomes unstable, and increased reactions with the electrolyte at the particle surface and interface lead to the release of large amounts of gas during repeated charge-discharge processes, resulting in a problem of reduced lifespan characteristics. Figure 1 is an SEM image of the surface of a positive electrode active material particle according to one embodiment of the present invention. Figure 2 is an SEM image of the surface of a positive electrode active material particle according to one embodiment of the present invention. Expressions such as "comprising" as used in this specification should be understood as open-ended terms implying the possibility of including other configurations. As used herein, "preferably" and "preferably" refer to embodiments of the invention that can provide certain advantages under certain conditions. However, it is not intended to exclude other embodiments from the scope of the invention. Furthermore, the singular form used in the specification and the appended claims may be intended to include the plural form unless specifically indicated otherwise in the context. That is, a technical feature of a single particle may mean a technical feature of multiple particles, or may be intended to mean an average technical feature of multiple particles. The numerical ranges used in this specification include lower and upper limits and all values within the range, increments logically derived from the form and width of the defined range, all of which are limited values, and all possible combinations of upper and lower limits of numerical ranges limited in different forms. Unless otherwise specifically defined in this specification, values outside the numerical range that may occur due to experimental error or rounding are also included in the defined numerical range. The meanings of '≤', 'greater than or equal to', or 'less than or equal to' as described in this specification may be replaced with the meanings of '<', 'greater than', or 'less than'. Meanwhile, the technical features described below relate to one embodiment that achieves the intended effe