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KR-20260064394-A - Negative electrode active material for secondary battery, method for preparing the same and lithium secondary battery including the same

KR20260064394AKR 20260064394 AKR20260064394 AKR 20260064394AKR-20260064394-A

Abstract

One embodiment of the present invention provides a negative electrode active material for a secondary battery comprising silicon-based particles; and a shell located on the silicon-based particles and containing silicon oxynitride (Si-NO), wherein the total amount of nitrogen (N) and oxygen (O) is 12% by weight or less relative to the total weight of the core and the shell. Another embodiment of the present invention provides a method for manufacturing a negative electrode active material for a secondary battery comprising: a preparation step of preparing silicon-based particle raw materials; and a microwave heating step of irradiating the silicon-based particles with microwaves to form a shell containing silicon oxynitride (Si-NO), wherein the microwave heating involves rapidly heating at least a portion of the surface of the silicon-based particles to 1,000°C or higher in a nitrogen atmosphere ( N₂ ).

Inventors

  • 서유경
  • 이동욱
  • 이총민
  • 채태성
  • 전민영

Assignees

  • 주식회사 에코프로비엠

Dates

Publication Date
20260507
Application Date
20241031

Claims (20)

  1. A core containing silicon-based particles; and It comprises a shell located on the above core and containing silicon (Si), nitrogen (N) and oxygen (O), and A negative electrode active material for a secondary battery, wherein, with respect to the total weight of the core and shell, the total sum of nitrogen (N) and oxygen (O) (N+O) is 12 weight% or less and the weight ratio (N/O) is 1 to 10%.
  2. In paragraph 1, A negative electrode active material for a secondary battery, wherein the total amount of nitrogen (N) and oxygen (O) is 0.5 to 4.5 weight% with respect to the total weight of the core and shell.
  3. In paragraph 1, A negative electrode active material for a secondary battery, comprising 0.01 to 2 weight% nitrogen (N) and 1.5 to 4.5 weight% oxygen (O) based on the total weight of the core and shell.
  4. In paragraph 1, A negative electrode active material for a secondary battery in which the ratio of nitrogen (N) weight to oxygen (O) weight (N/O) of the core and shell is 1 to 5%.
  5. In paragraph 1, The above shell is a negative electrode active material for a secondary battery containing silicon oxynitride (Si-NO).
  6. In paragraph 5, The above shell is a negative electrode active material for a secondary battery comprising a compound represented by the following chemical formula 1: [Chemical Formula 1] Si x N y O z In Chemical Formula 1, 1≤x≤4, 0≤y≤5, and 0≤z≤2.
  7. In paragraph 5, A negative electrode active material for a secondary battery, wherein the shell comprises a compound represented by the following chemical formula 1-1, and optionally further comprises a compound represented by the following chemical formula 1-2: [Chemical Formula 1-1] Si x1 N y1 O z1 In the above chemical formula 1-1, 1<x1<4, 1<y<4, 0<z<2, [Chemical Formula 1-2] SiO z2 In the above chemical formula 1-2, 0 < z2 < 2.
  8. In paragraph 1, The above negative electrode active material is a negative electrode active material for a secondary battery having a peak area ratio A/B of 70 to 100 according to X-ray diffraction analysis. (A is the area of the Si (111) peak located at 28.4±0.3° in the X-ray diffraction analysis, and B is the area of the Si 2 N 2 O (110) peak located at 18.9±0.1° in the X-ray diffraction analysis)
  9. In paragraph 1, A negative electrode active material for a secondary battery, wherein the thickness of the shell is 0.5 to 10 nm.
  10. In paragraph 1, The silicon-based particles of the above core are a negative electrode active material for a secondary battery, wherein the silicon (Si) crystal grain size is 10 to 30 nm.
  11. In paragraph 1, The silicon-based particles of the core are a negative electrode active material for a secondary battery, wherein the rate of increase of the silicon (Si) crystallinity after shell formation relative to the silicon (Si) crystallinity before shell formation is 15% or less.
  12. In paragraph 1, The above silicon-based particles comprise at least one selected from silicon (Si) microparticles, silicon (Si) nanoparticles, and silicon oxide (SiOx, 0.8≤x≤2) particles, making it a negative electrode active material for a secondary battery.
  13. a) a preparation step of introducing silicon-based particle raw materials into a reactor; and b) a microwave heating step comprising irradiating the silicon-based particles with microwaves to form a shell containing silicon oxynitride (Si-NO), and A method for manufacturing a negative electrode active material for a secondary battery, wherein the microwave heating is performed by irradiating microwaves in a nitrogen atmosphere ( N₂ ) to rapidly heat at least a portion of the surface of the silicon-based particles to 1,000°C or higher.
  14. In Paragraph 13, A method for manufacturing a negative electrode active material for a secondary battery, wherein the above preparation step a) involves maintaining the reactor at a vacuum of 10⁻⁸ to 10⁻⁴ torr and then injecting nitrogen to a pressure of 0.5 to 2 bar.
  15. In Paragraph 13, A method for manufacturing a negative electrode active material for a secondary battery, wherein, in the above preparation step a), the silicon-based particles comprise a silicon oxide (SiOx, 0<x≤2) film layer on their surface in an amount of 1 to 5 weight%.
  16. In Paragraph 13, A method for manufacturing a negative electrode active material for a secondary battery, wherein in the heating step b) above, the nitrogen atmosphere ( N₂ ) is a gaseous atmosphere of 99 to 99.999 volume% nitrogen.
  17. In Paragraph 13, A method for manufacturing a negative electrode active material for a secondary battery, wherein in the above b) heating step, the microwave heating is performed by irradiating microwaves for 30 seconds to 180 seconds with an output of 1 to 3 kW.
  18. In Paragraph 13, A method for manufacturing a negative electrode active material for a secondary battery, wherein the heating step b) above is performed to satisfy the following equations 1 and 2: [Relationship 1] -55 < (O b -O a )/T a (%) < -45 [Relationship 2] 1 < (N b -N a )/T a (%) < 5 In relational expressions 1 and 2, O a , Na, and T a are, respectively, the oxygen (O) content (weight%) (O a), the nitrogen (N) content (weight%) (Na a ), and the total nitrogen (N) and oxygen (O) content ( weight %) relative to the total elements of the silicon-based particle raw material in the preparation step a ) above, and O b and N b are, respectively, the oxygen (O) content (weight%) (O b ) and nitrogen (N) content (weight%) (N b ) relative to the total elements of the silicon-based particles in which the shell was formed in the heating step b) above.
  19. A negative electrode for a secondary battery comprising a negative electrode active material according to any one of claims 1 to 12.
  20. A secondary battery comprising a negative electrode according to paragraph 19.

Description

Negative electrode active material for secondary battery, method for preparing the same and lithium secondary battery including the same The present invention relates to a negative electrode active material for a secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same. With the recent increase in demand for electronic devices, including mobile phones, technological development for these devices is expanding. Consequently, the demand for lithium-ion batteries, such as lithium batteries, lithium-ion batteries, and lithium-ion polymer batteries, is rising significantly as power sources for these electronic devices. Furthermore, driven by the global trend of tightening regulations on vehicle fuel efficiency and exhaust emissions, the growth of the electric vehicle (EV) market is accelerating. Along with this, demand for medium- and large-sized secondary batteries, such as those for EVs and Energy Storage Systems (ESS), is expected to surge. Meanwhile, as the demand for higher capacity in secondary batteries, such as medium and large-sized batteries, has recently increased, silicon-based anode materials with excellent theoretical capacity are being researched as anode materials for secondary batteries. However, silicon-based anode materials cause significant volume changes during lithium insertion and extraction, leading to electrical delamination due to silicon particle pulverization and reversible capacity loss under repeated cycles. Prior art document 1 (Published patent CN 114420912 A) discloses a silicon anode material in which a silicon nitrogen layer is formed by treating silicon with a hydrofluoric acid solution and then heating it to 780°C in a nitrogen atmosphere. However, the silicon nitrogen layer synthesized in the heating furnace has an excessively high nitrogen content, which causes a problem in that the capacitance characteristics are degraded. Prior art document 2 (Published Patent 10-2005-0016126) relates to a lithium-ion secondary battery negative electrode material in which a metallic silicon powder is surface-oxidized or surface-nitrided in a heating furnace to coat the surface of the metallic silicon with an inert material containing silicon dioxide, silicon carbide, silicon nitride, or silicon oxynitride. However, since a high content of the inert material is coated, there is a problem in that the irreversible phase increases and the capacity is limited. Figure 1 is a TEM (Transmission electron microscopy) image of the negative electrode active material prepared in Example 1. Figure 2 shows the X-ray diffraction (XRD) analysis results of the cathode active materials prepared in Example 1 and Comparative Examples 1 to 3. The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning that is commonly understood by those skilled in the art to which the present invention pertains. Throughout the specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. Additionally, when a part such as a layer, film, region, plate, etc. is described in this specification as being “on” or “on” another part, this includes not only cases where it is “immediately on” another part, but also cases where there is another part in between. In this specification, "A to B" means "A or more and B or less" unless specifically defined otherwise. Additionally, "A and/or B" means at least one selected from the group consisting of A and B, unless specifically defined otherwise. One embodiment of the present invention provides a negative electrode active material for a secondary battery comprising: a core containing silicon-based particles; and a shell positioned on the core containing silicon (Si), nitrogen (N), and oxygen (O), wherein the total sum (N+O) of nitrogen (N) and oxygen (O) is 12 weight% or less and the weight ratio (N/O) is 1 to 10% with respect to the total weight of the core and the shell. Specifically, silicon-based particles have the advantage of high capacity compared to conventional graphite anode active materials; however, it is analyzed that the destru