Search

KR-20260067955-A - ANODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY INCLUDING THE SAME

KR20260067955AKR 20260067955 AKR20260067955 AKR 20260067955AKR-20260067955-A

Abstract

The negative electrode active material for a lithium secondary battery according to the embodiments of the present disclosure comprises a silicon-based active material. The silicon-based active material comprises silicon oxide particles and a carbon coating layer formed on at least a portion of the surface of the silicon oxide particles. The O1s peak area ratio defined by a predetermined formula of the silicon-based active material is 0.025 to 0.045.

Inventors

  • 박양규
  • 김선아
  • 이종혁
  • 정주호
  • 최재영

Assignees

  • 에스케이온 주식회사
  • 에스케이이노베이션 주식회사

Dates

Publication Date
20260513
Application Date
20250408
Priority Date
20241104

Claims (20)

  1. A silicon-based active material comprising silicon oxide particles and a carbon coating layer formed on at least a portion of the surface of the silicon oxide particles, and A negative electrode active material for a lithium secondary battery, wherein the O1s peak area ratio, defined by Equation 1 below and measured by X-ray photoemission spectroscopy (XPS) analysis of the above silicon-based active material, is 0.025 to 0.045: [Equation 1] O1s peak area ratio = A O /A H (In Equation 1, A₀ is the area of the O1s peak measured by performing XPS on the silicon-based active material, and A₆H is the area of the Si-OH peak measured by performing XPS on the silicon-based active material).
  2. A negative electrode active material for a lithium secondary battery according to claim 1, wherein the O1s peak area ratio of the silicon-based active material is 0.026 to 0.04.
  3. A negative electrode active material for a lithium secondary battery according to claim 1, wherein the C1s peak area ratio, which is measured by X-ray photoluminescence spectroscopy (XPS) analysis of the silicon-based active material and defined by the following formula 2, is 0.2 to 1: [Equation 2] C1s peak area ratio = AC / A L (In Equation 2, AC is the area of the C1s peak measured by performing XPS on the silicon-based active material, and A L is the area of the Li₂CO₃ peak measured by performing XPS on the silicon-based active material).
  4. A negative electrode active material for a lithium secondary battery according to claim 3, wherein the C1s peak area ratio of the silicon-based active material is 0.4 to 0.8.
  5. A negative electrode active material for a lithium secondary battery according to claim 1, wherein the silicon oxide particles comprise SiO x (0<x≤2).
  6. A negative electrode active material for a lithium secondary battery according to claim 1, wherein the surface arithmetic mean roughness (Ra) measured using an atomic force microscope (AFM) for the silicon-based active material is 0.2 nm to 5 nm.
  7. A negative electrode active material for a lithium secondary battery according to claim 6, wherein the surface arithmetic mean roughness (Ra) of the silicon-based active material is 2 nm to 4.5 nm.
  8. A negative electrode active material for a lithium secondary battery according to claim 6, wherein the surface arithmetic mean roughness (Ra) is the arithmetic mean of roughness values excluding the maximum and minimum values among surface roughness values measured with a scan range of 0.5㎛ × 0.5㎛ for 10 to 20 regions of the surface of the silicon-based active material.
  9. A negative electrode active material for a lithium secondary battery according to claim 8, wherein the standard deviation of roughness values, excluding the maximum and minimum values among the measured surface roughness values, is 1.5 nm to 8 nm.
  10. A negative electrode active material for a lithium secondary battery according to claim 1, wherein the peak intensity ratio of the Raman spectroscopic spectrum defined by the following formula 3 is 0.5 to 5.5: [Equation 3] Raman spectroscopic peak intensity ratio = I(520)/I(470) (In Equation 3, I (520) is the peak intensity of the silicon oxide particle in the region where the wavelength is 520 nm - 1 in the Raman spectroscopic spectrum, and I (470) is the peak intensity of the silicon oxide particle in the region where the wavelength is 470 nm - 1 in the Raman spectroscopic spectrum).
  11. A negative electrode active material for a lithium secondary battery according to claim 1, wherein the crystallite size of the silicon oxide particles, measured by XRD analysis and defined by the following formula 4, is 3 nm to 5 nm: [Equation 4] (In Equation 4, L is the crystallite size (nm), λ is the X-ray wavelength (nm), β is the full width at half maximum of the peak of the (111) plane of the silicon oxide particle (rad), and θ is the diffraction angle (rad).)
  12. A negative electrode active material for a lithium secondary battery according to claim 1, wherein the specific surface area of the silicon-based active material is 1 m² /g to 4 m² /g.
  13. A negative electrode active material for a lithium secondary battery according to claim 1, wherein the average particle size (D50) of the silicon oxide particles is 4 μm to 6 μm.
  14. A negative electrode active material for a lithium secondary battery, wherein the negative electrode active material of claim 1 further comprises a carbon-based active material.
  15. A negative electrode active material for a lithium secondary battery according to claim 14, wherein the carbon-based active material comprises artificial graphite, natural graphite, or a mixture thereof.
  16. A negative electrode active material for a lithium secondary battery according to claim 1, wherein the content of the silicon-based active material is greater than 0% by weight and less than or equal to 10% by weight of the total weight of the negative electrode active material.
  17. A step of obtaining silicon oxide particles by mixing and heat-treating silicon sources; and The method includes the step of obtaining a silicon-based active material by reacting the silicon oxide particles with carbon gas to form a carbon coating layer. A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the O1s peak area ratio, defined by Formula 1 below and measured by X-ray photoemission spectroscopy (XPS) analysis of the silicon-based active material, is 0.025 to 0.045: [Equation 1] O1s peak area ratio = A O /A H (In Equation 1, A₀ is the area of the O1s peak measured by performing XPS on the silicon-based active material, and A₆H is the area of the Si-OH peak measured by performing XPS on the silicon-based active material).
  18. A method for manufacturing a negative electrode active material for a lithium secondary battery according to claim 17, wherein the heat treatment temperature is 800°C to 1200°C.
  19. A method for manufacturing a negative electrode active material for a lithium secondary battery according to claim 17, wherein the silicon source comprises silicon particles and silicon dioxide ( SiO2 ) particles.
  20. A cathode comprising a cathode active material according to claim 1; and A lithium secondary battery comprising a positive electrode facing the above-mentioned negative electrode.

Description

Anode active material for lithium secondary battery, method for manufacturing the same, and lithium secondary battery including the same The present disclosure relates to a negative electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including 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 are widely applied as power sources for portable electronic communication devices such as camcorders, mobile phones, and laptop PCs. Furthermore, recently, battery packs containing rechargeable batteries are being developed and applied as power sources for eco-friendly vehicles, such as hybrid cars. Examples of secondary batteries include lithium-ion batteries, nickel-cadmium batteries, and nickel-hydrogen batteries; among these, active research and development is being conducted on lithium-ion batteries due to their high operating voltage and energy density per unit weight, as well as their advantages in charging speed and weight reduction. For example, a lithium secondary battery may include a positive electrode and a negative electrode. Electrodes such as the positive and negative electrodes contain electrode active materials that can reversibly absorb and release lithium ions. Current can be generated through chemical reactions at the electrodes. Graphite-based or silicon-based materials may be used as the active material for the negative electrode. While silicon-based active materials provide high energy density, volume expansion or mechanical and chemical defects may occur during the charging and discharging process, which can reduce the lifespan of the secondary battery. FIGS. 1 and FIGS. 2 are a schematic plan view and a cross-sectional view of a lithium secondary battery according to exemplary embodiments, respectively. According to embodiments of the present disclosure, a negative electrode active material for a lithium secondary battery comprising a silicon-based active material is provided. According to embodiments of the present disclosure, a cathode and a lithium secondary battery comprising the cathode active material are provided. Hereinafter, embodiments of the present disclosure will be described in detail. However, this is merely illustrative and the present disclosure is not limited to the specific embodiments described illustratively. A negative electrode active material for a lithium secondary battery according to the embodiments of the present disclosure (hereinafter abbreviated as "negative electrode active material") comprises a silicon-based active material. The silicon-based active material comprises silicon oxide particles. Silicon oxide particles possess high energy density, which can improve the initial efficiency and charge/discharge capacity of the cathode active material. However, silicon oxide particles can react with the electrolyte to form a solid electrolyte interphase (SEI), which can cause gas generation and increased resistance due to the irreversible decomposition of the electrolyte, thereby degrading capacity and lifespan characteristics. According to exemplary embodiments of the present disclosure, silicon oxide may include at least a crystal structure. According to one embodiment, the silicon oxide may include both a crystalline structure and an amorphous structure. For example, the volume expansion of the negative electrode active material and side reactions with the electrolyte can be suppressed by the crystalline structure. Additionally, the crystallite size of the silicon oxide particles and the ratio of the crystalline region to the amorphous region can be maintained within an appropriate range by the amorphous structure. Accordingly, a secondary battery with improved capacity characteristics and lifespan characteristics can be provided. According to exemplary embodiments, the O1s peak area ratio, which is measured by X-ray photoemission spectroscopy (XPS) analysis and defined by the following Equation 1, is 0.025 to 0.045. [Equation 1] O1s peak area ratio = A O /A H In Equation 1, A0 is the area of the O1s peak measured by performing XPS on the silicon-based active material, and AH is the area of the Si-OH peak measured by performing XPS on the silicon-based active material. For example, the O1s spectrum according to XPS analysis of the silicon oxide particles may include a Si-OH peak in the region with a binding energy of 530.8 eV, a Si-O X peak in the region with a binding energy of 532.5 eV, and a Si-O-Si peak in the region with a binding energy of 533.7 eV. For example, if the O1s peak area ratio increases, it may indicate that the number of -OH bonds within the silicon oxide particles increases and the crystallinity of the silicon oxide particles decreases. For example, if the O1s peak area ratio decreases, it may indicate that the number of -OH bonds within