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KR-20260064279-A - CATHODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY INCLUDING THE SAME

KR20260064279AKR 20260064279 AKR20260064279 AKR 20260064279AKR-20260064279-A

Abstract

In the active material for a lithium secondary battery according to exemplary embodiments, S of Formula 1 below may be 100 to 500: [Equation 1] S = A/B (In the equation, A is the maximum peak intensity in the 4.2V to 4.3V region of the dQ/dV discharge graph, and B is the peak intensity at 4.5V in the dQ/dV discharge graph). Accordingly, the positive electrode active material has excellent structural stability, and a secondary battery with improved lifespan characteristics is provided.

Inventors

  • 김홍기
  • 노미정
  • 박혜진
  • 이윤지

Assignees

  • 에스케이온 주식회사

Dates

Publication Date
20260507
Application Date
20241031

Claims (18)

  1. A positive electrode active material for a lithium secondary battery, wherein S of Formula 1 below is 100 to 500: [Equation 1] S = A/B (In the equation, A is the maximum peak intensity in the 4.2V to 4.3V region of the dQ/dV discharge graph, and B is the peak intensity at 4.5V of the dQ/dV discharge graph).
  2. A positive electrode active material for a lithium secondary battery according to claim 1, wherein B is -2 or more and less than 0.
  3. A positive electrode active material for a lithium secondary battery according to claim 1, wherein A is -1,000 or more to -200 or less.
  4. A positive electrode active material for a lithium secondary battery according to claim 1, wherein S is 200 to 500.
  5. A positive electrode active material for a lithium secondary battery according to claim 1, wherein the dQ/dV discharge graph is calculated by performing charging (CC/CV 0.1C 4.6V 0.05C CUT-OFF) and discharging (CV 0.1C 3V CUT-OFF) in a 25℃ chamber for a half cell manufactured with the positive electrode active material, and calculating the change in charge amount with respect to the voltage change measured during the charging and discharging.
  6. A positive active material for a lithium secondary battery according to claim 1, wherein the positive active material comprises a lithium metal oxide represented by the following chemical formula 1: [Chemical Formula 1] Li x Ni a M b O 2+z (In Chemical Formula 1, M is at least one of Co, Mn and Al, and 0.9≤x≤1.2, 0.6≤a≤0.8, 0.2≤b≤0.4, -0.5≤z≤0.1).
  7. A positive active material for a lithium secondary battery according to claim 1, wherein the positive active material comprises a lithium metal oxide represented by the following chemical formula 1-1: [Chemical Formula 1-1] Li x Ni a M1 b1 M2 b2 O 2+z (In Chemical Formula 1-1, M1 is at least one of Co, Mn, and Al, and M2 is at least one of Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si, Sn, Sr, Ba, Ra, P, and Zr, and 0.9≤x≤1.2, 0.6≤a≤0.8, 0.2≤b1+b2≤0.4, -0.5≤z≤0.1).
  8. The positive active material of claim 6, wherein the positive active material is a positive active material for a lithium secondary battery in which M is Co and Mn and 0.6≤a≤0.7.
  9. In claim 6, the positive electrode active material comprises a lithium metal compound core represented by the chemical formula 1 and a coating layer covering at least a portion of the core, and The above coating layer is a positive electrode active material for a lithium secondary battery comprising the element M of the above chemical formula 1.
  10. A positive electrode active material for a lithium secondary battery according to claim 9, wherein the coating element content of the coating layer is 0.5 mol% to 3 mol% based on elements excluding lithium and oxygen in the positive electrode active material.
  11. In claim 7, the positive electrode active material comprises a lithium metal compound core represented by the formula 1-1 and a coating layer covering at least a portion of the core, and The above coating layer is a positive electrode active material for a lithium secondary battery comprising the M1 element of the above chemical formula 1.
  12. A positive electrode active material for a lithium secondary battery according to claim 11, wherein the coating element content of the coating layer is 0.5 mol% to 3 mol% based on elements excluding lithium and oxygen in the positive electrode active material.
  13. The positive active material of claim 1, wherein the positive active material is a positive active material for a lithium secondary battery having a crystal size of (003) planes measured by X-ray diffraction (XRD) of 300 nm to 850 nm.
  14. A method for manufacturing a positive electrode active material for a lithium secondary battery comprising the step of mixing and calcining a transition metal precursor and a lithium precursor, wherein A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the positive electrode active material for the lithium secondary battery has S of Formula 1 below being 100 to 500: [Equation 1] S = A/B (In the equation, A is the maximum peak intensity in the 4.2V to 4.3V region of the dQ/dV discharge graph, and B is the peak intensity at 4.5V of the dQ/dV discharge graph).
  15. A method for manufacturing a positive electrode active material for a lithium secondary battery according to claim 14, wherein the calcination temperature is 900℃ to 1,000℃.
  16. A method for manufacturing a positive electrode active material for a lithium secondary battery according to claim 14, wherein the heating rate in the calcination step is 2℃/min to 4℃/min.
  17. A method for manufacturing a positive electrode active material for a lithium secondary battery according to claim 14, wherein the holding time during calcination is 8 to 14 hours.
  18. Anode; and It includes a cathode positioned opposite to the anode, and A lithium secondary battery comprising a positive electrode according to claim 1.

Description

Cathode active material for lithium secondary battery and lithium secondary battery including the same The present disclosure relates to a positive electrode active material for a lithium secondary battery and a lithium secondary battery comprising the same. More specifically, it relates to a positive electrode active material for a lithium secondary battery having excellent structural stability and a lithium secondary battery comprising the same. Rechargeable batteries are batteries capable of repeated charging and discharging, and with the advancement of the information and communication and display industries, they have been widely applied in portable electronic communication devices such as camcorders, mobile phones, and laptop PCs. Examples of rechargeable batteries include lithium-ion batteries, nickel-cadmium batteries, and nickel-hydrogen batteries; among these, lithium-ion batteries have been actively developed and applied due to their high operating voltage and energy density per unit weight, as well as advantages in charging speed and weight reduction. For example, a lithium secondary battery may include an electrode assembly comprising a positive electrode, a negative electrode, and a separator, and an electrolyte impregnating the electrode assembly. The lithium secondary battery may further include an outer casing, for example, in the form of a pouch, that accommodates the electrode assembly and the electrolyte. Lithium-ion batteries can improve energy density and output performance when operated under high-voltage conditions. However, structural breakdown of the cathode active material and adverse reactions with the electrolyte in high-voltage environments can degrade the stability and performance of the battery. FIG. 1 is a schematic plan view showing a lithium secondary battery according to exemplary embodiments. FIG. 2 is a schematic cross-sectional view showing an electrode assembly according to exemplary embodiments. FIG. 3 is a dQ/dV graph according to Example 1 of the present disclosure. Figure 4 is a dQ/dV graph according to Comparative Example 1. According to embodiments of the present disclosure, a positive active material having a specific peak ratio in a dQ/dV graph is provided. Additionally, according to embodiments of the present disclosure, a lithium secondary battery comprising said positive active material is provided. Hereinafter, specific embodiments of the present disclosure will be described together with the accompanying drawings. However, this is merely an example and the inventive concept of the present disclosure is not limited thereto. Furthermore, the accompanying drawings represent exemplary structures, and the configurations and structures of the present disclosure are not limited to those disclosed in the drawings. <Cathode Active Material> In the positive active material according to exemplary embodiments, S of Formula 1 below may be 100 to 500: [Equation 1] S = A/B (In the equation, A is the maximum peak intensity in the 4.2V to 4.3V region of the dQ/dV discharge graph, and B is the peak intensity at 4.5V of the dQ/dV discharge graph) The dQ/dV graph of a secondary battery can serve as an indicator of chemical and/or physical changes within the battery. The positive electrode active material according to the embodiments of the present disclosure can improve the structural stability of the positive electrode active material during high-voltage operation of the battery by ensuring that the ratio of the maximum peak intensity in the 4.2V to 4.3V region to the peak intensity at 4.5V in the dQ/dV discharge graph falls within the said range. Improved structural stability of the positive electrode active material can improve the lifespan characteristics of the battery. In this regard, for example, S can be 200 to 500, 250 to 500, or 300 to 500. The lifespan characteristics of the battery can be improved within the said range. For example, the peak at 4.5V in the dQ/dV discharge graph can serve as an indicator of structural changes in the positive electrode active material during high-voltage operation. A relatively smaller peak at 4.5V in the dQ/dV discharge graph may indicate that there are fewer structural changes in the positive electrode active material during high-voltage operation, and accordingly, the structural stability of the positive electrode active material may be higher. For example, in Equation 1 above, B may be -2 or more to less than 0, -1.7 or more to less than 0, -1.5 or more to less than 0, -1.3 or more to less than 0, -1.0 or more to less than 0, -0.8 or more to less than 0, or -0.5 or more to less than 0. The structural stability of the positive electrode active material may be higher when B is within the above range. In the same vein, for example, in Formula 1 above, A may be -1,000 or more to -200 or less, -800 or more to -200 or less, -700 or more to -200 or less, or -500 or more to -200 or less. The structural stability of the positive electro