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KR-20260064065-A - CATHODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY, METHODE OF PREPARING THE SAME AND LITHIUM SECONDARY BATTERY

KR20260064065AKR 20260064065 AKR20260064065 AKR 20260064065AKR-20260064065-A

Abstract

A positive active material for a lithium secondary battery is provided, which is a positive active material comprising a lithium metal oxide and satisfies Formula 1 below. [Equation 1] Charge Transfer Resistance (RCT) ≤ 30 Ω (In Equation 1 above, RCT is based on values measured by electrochemical impedance spectroscopy (EIS) for a half-coin cell including a cathode to which the cathode active material is applied).

Inventors

  • 최지훈
  • 권희준
  • 장지혜

Assignees

  • 에스케이온 주식회사

Dates

Publication Date
20260507
Application Date
20241031

Claims (20)

  1. It is a positive electrode active material containing lithium metal oxide, and A positive electrode active material for a lithium secondary battery satisfying Formula 1 below: [Equation 1] Charge Transfer Resistance ( RCT ) ≤ 30 Ω (In Equation 1 above, R CT is based on the value measured by electrochemical impedance spectroscopy (EIS) for a half-coin cell containing a cathode to which the cathode active material is applied).
  2. In paragraph 1, A positive electrode active material for a lithium secondary battery, wherein the content of residual lithium present on the surface of the above lithium metal oxide is less than 5000 ppm.
  3. In paragraph 1, A positive electrode active material for a lithium secondary battery, further comprising a coating layer formed on at least a portion of the surface of the lithium metal oxide, wherein the coating layer comprises an inorganic material comprising at least one of a metal element, a metalloid element, and a non-metal element.
  4. In paragraph 3, A positive electrode active material for a lithium secondary battery, wherein the metal element comprises at least one selected from the group consisting of aluminum, tungsten, cobalt, zirconium, molybdenum, niobium, and titanium, the metalloid element comprises boron, and the nonmetal element comprises sulfur.
  5. In paragraph 3, The above inorganic material is a positive electrode active material for a lithium secondary battery, comprising tungsten.
  6. In paragraph 3, A positive electrode active material for a lithium secondary battery, wherein the deviation in inorganic content over the entire area of the coating layer is less than 10%.
  7. In paragraph 5, A positive electrode active material for a lithium secondary battery, wherein the deviation of the inorganic content containing tungsten in the entire area of the coating layer is less than 10%.
  8. Step of preparing a preliminary lithium metal oxide; and A method for manufacturing a positive electrode active material for a lithium secondary battery, comprising the step of treating the above-mentioned preliminary lithium metal oxide with flake ice.
  9. In paragraph 8, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the above-mentioned preliminary lithium metal oxide is not treated with water or steam.
  10. In paragraph 8, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the average crystal size of the flake ice is 0.05 mm to 0.5 mm.
  11. In paragraph 8, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the treatment with the flake ice is performed using 1 to 3 parts by weight of the flake ice per 100 parts by weight of the pre-lithium metal oxide.
  12. In paragraph 8, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the above-mentioned treatment with flake ice is performed in a temperature range of -35℃ to 35℃.
  13. In paragraph 8, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the preliminary lithium metal oxide and the flake ice are introduced into the blender and blended to treat the preliminary lithium metal oxide with flake ice.
  14. In paragraph 8, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the above-mentioned preliminary lithium metal oxide and inorganic material are introduced into the above-mentioned blender and blended, and then the above-mentioned flake ice is introduced and blended.
  15. In Paragraph 14, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the above-mentioned inorganic material comprises at least one of a metallic element, a metalloid element, and a non-metallic element.
  16. In Paragraph 14, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the time for blending the preliminary lithium metal oxide and the flake ice from the time the preliminary lithium metal oxide and the inorganic material are introduced into the blender is 3 minutes to 15 minutes.
  17. In Paragraph 14, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the inorganic material is introduced into the blender at a concentration of 1,000 ppm to 9,000 ppm per 1 kg of the pre-lithium metal oxide.
  18. In paragraph 8, A method for manufacturing a positive electrode active material for a lithium secondary battery, further comprising the step of calcining a treated preliminary lithium metal oxide at least once to obtain a lithium metal oxide.
  19. In Paragraph 18, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the loss rate (%) of the lithium metal oxide according to Formula 2 below is less than 0.5%: [Equation 2] Loss rate (%) = (In Equation 2 above, A1 is the amount of lithium metal oxide that has undergone calcination treatment, and A2 is the amount of lithium metal oxide classified by sieving the lithium metal oxide that has undergone calcination treatment through a 325 mesh sieve).
  20. A lithium secondary battery comprising a positive electrode including a positive electrode active material for a lithium secondary battery according to claim 1, and a negative electrode facing the positive electrode.

Description

Cathode active material for lithium secondary battery, method of preparing the same, and lithium secondary battery The disclosure of the present application relates to a positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery. Rechargeable batteries are batteries capable of repeated charging and discharging, and with the advancement of the information and communication and display industries, they are widely applied as power sources for portable electronic communication devices such as camcorders, mobile phones, and laptop PCs. Furthermore, battery packs containing rechargeable batteries are being developed and applied as power sources for eco-friendly vehicles, such as electric vehicles. Examples of secondary batteries include lithium-ion batteries, nickel-cadmium batteries, and nickel-hydrogen batteries; among these, lithium-ion batteries have high operating voltage and energy density per unit weight, and are advantageous for charging speed and weight reduction. Lithium metal oxide is widely used as the cathode material for lithium secondary batteries. In the case of lithium metal oxides, a significant amount of residual lithium exists on their surface, so research and development regarding cleaning processes to remove it are underway. FIG. 1 is a schematic process flow diagram of a method for manufacturing a positive electrode active material for a lithium secondary battery according to exemplary embodiments. Figure 2 is an exemplary image of flake ice. FIG. 3 is a schematic plan view of a lithium secondary battery according to exemplary embodiments. FIG. 4 is a schematic cross-sectional view of a lithium secondary battery according to exemplary embodiments. Figure 5 is a Nyquist plot graph for a half coin cell with the positive active material according to Example 1 and Comparative Example 1. With reference to the drawings below, exemplary embodiments of the present disclosure are described in detail so that those skilled in the art can easily practice the present invention. However, this is merely illustrative and the present invention is not limited to the exemplary embodiments described. Cathode active material for lithium secondary batteries A positive electrode active material according to exemplary embodiments of the present disclosure comprises a lithium metal oxide. The lithium metal oxide satisfies Formula 1 below, and accordingly, a positive electrode to which the positive electrode active material is applied has improved electrical conductivity and the interfacial resistance of the surface can be reduced. [Equation 1] Charge Transfer Resistance ( RCT ) ≤ 30 Ω In Equation 1, R CT is based on the value measured by electrochemical impedance spectroscopy (EIS) for a half-coin cell containing a positive electrode to which the positive active material is applied. R CT can be, for example, 29 Ω or less, 28 Ω or less, 27 Ω or less, and 20 Ω or more. The anode can be formed, for example, by applying an anode slurry containing the anode active material onto an anode current collector and drying under reduced pressure, or by drying and rolling. Accordingly, the anode may include an anode current collector and an anode active material layer. The mass of the anode active material layer per unit area of the anode where R CT is measured can be 9 mg/ cm² to 11 mg/ cm² , and, for example, 10±0.5 mg/ cm² . The composite density of the anode at which R CT is measured can be 34 g/ cm³ to 36 g/ cm³ , and, for example, 3.5 ± 0.1 g/ cm³ . The total thickness of the anode where R CT is measured can be 45㎛ to 55㎛, for example 48㎛ to 52㎛, or 50±1㎛. The above positive current collector may include a metal foil, a metal plate, etc. The metal foil or the metal plate may include, for example, metals such as stainless steel, iron, aluminum, copper, germanium, nickel, titanium, magnesium, or an alloy of two or more of these. The anode slurry may further include at least one selected from the group consisting of, for example, a binder, a conductive material, and a solvent. As a non-limiting example, the binder may include, for example, organic binders such as vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidenefluoride (PVDF), polyacrylonitrile, and polymethylmethacrylate, and water-based binders such as styrene-butadiene rubber (SBR). These may be used alone or in combination of two or more. The binder may be used with a thickener such as carboxymethyl cellulose (CMC). As a non-limiting example, the conductive material may include, for example, a linear conductive material, a point conductive material, or both. The linear conductive material may include, for example, carbon nanotubes (CNT), and the carbon nanotubes (CNT) may include single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT), multi-walled carbon nanotubes (MWCNT), rope carbon nanotubes, etc. The above solvent may include, for exampl