Search

KR-20260065118-A - Negative electrode active material for secondary battery, method for preparing the same and lithium secondary battery including the same

KR20260065118AKR 20260065118 AKR20260065118 AKR 20260065118AKR-20260065118-A

Abstract

One embodiment of the present invention provides a negative electrode active material for a secondary battery comprising a silicon-based composite comprising silicon (Si); and a first compound composed of at least silicon (Si) and nitrogen (N), satisfying Equation 1.

Inventors

  • 채태성
  • 서유경
  • 이총민
  • 전민영
  • 이동욱

Assignees

  • 주식회사 에코프로비엠

Dates

Publication Date
20260508
Application Date
20241031

Claims (15)

  1. A silicon-based composite comprising silicon (Si); and a first compound composed of at least silicon (Si) and nitrogen (N), and A negative electrode active material for a secondary battery satisfying the following relationship 1: [Relationship 1] 0.5 < B/A (nm/wt%) < 50 In Equation 1, A is the content of N relative to Si (N/Si) (wt%), and B is the Si grain size (nm).
  2. In paragraph 1, The content of N relative to the above Si (N/Si) is 0.5 to 15 wt%, and A negative electrode active material for a secondary battery, wherein the crystal grain size of the silicon (Si) is less than 50 nm.
  3. In paragraph 1, The above-mentioned first compound comprises at least one selected from silicon nitride and silicon oxynitride, a negative electrode active material for a secondary battery.
  4. In paragraph 1, The above silicon-based composite further comprises silicon carbide (SiC), which is a second compound, and A negative electrode active material for a secondary battery having a peak area ratio D/C of 0.1 to 1 according to X-ray diffraction analysis. (C above is the peak area of silicon (Si) in X-ray diffraction analysis, and D above is the peak area of silicon carbide (SiC))
  5. In paragraph 1, It further includes carbon-based materials, The above carbon-based material is at least one selected from the group consisting of natural graphite, artificial graphite, expanded graphite, graphene oxide, carbon nanotubes, carbon fibers, and hard carbon, a negative electrode active material for a secondary battery.
  6. In paragraph 5, A negative electrode active material for a secondary battery comprising the above silicon-based composite and the above carbon-based material in a weight ratio of 6:4 to 9:1.
  7. In paragraph 1, The above silicon-based composite comprises a core containing silicon particles; and a shell formed on at least a portion of the silicon particles. The above shell is a negative electrode active material for a secondary battery comprising a first compound composed of at least silicon (Si) and nitrogen (N).
  8. In Paragraph 7, The above silicon-based composite has an average particle size (D50) of 10 to 800 nm, and The above coating layer is a negative electrode active material for a secondary battery having a thickness of 1 to 100 nm.
  9. In Paragraph 7, The above silicon-based composite is a negative electrode active material for a secondary battery, further comprising an amorphous carbon coating layer formed on the upper surface of the shell.
  10. A method for manufacturing a negative electrode active material for a secondary battery, comprising a microwave heating process in which a silicon-based composite is formed by mixing a silicon raw material and a nitrogen source and then irradiating with microwaves to form silicon particles; and a first compound composed of at least silicon (Si) and nitrogen (N).
  11. In Paragraph 10, The above microwave heating process is, A method for manufacturing a negative electrode active material for a secondary battery, wherein a carbon-based material is further mixed, and then microwaves are irradiated such that an exothermic temperature of 400 to 600°C appears in at least a portion of the carbon-based material.
  12. In Paragraph 10, The above silicon raw material includes nano-sized silicon particles, and A method for manufacturing a negative electrode active material for a secondary battery, wherein the above nitrogen source is a nitrogen (N)-containing organic compound having an N:C mole ratio of 1:1 to 1:5.
  13. In Paragraph 10, A method for manufacturing a negative electrode active material for a secondary battery, comprising a process for forming an amorphous carbon coating layer by mixing and heating the above silicon-based composite and an amorphous carbon source.
  14. A negative electrode for a secondary battery comprising a negative electrode active material according to any one of claims 1 to 9.
  15. A secondary battery comprising a negative electrode according to paragraph 14; a positive electrode; and an electrolyte.

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 the pulverization of silicon-based composites and problems of reversible capacity loss under repeated cycles. Research is being conducted to form a protective film composed of silicon carbide, silicon nitride, and amorphous carbon on the surface of silicon-based particles to improve cycle life characteristics when applying high-capacity silicon-based cathode materials. Prior art 1 (CN 107482200 A) presents a composite material in which silicon nitride and a carbon shell are sequentially formed on a silicon particle core, but there is a problem in that the reversible capacity is reduced because the crystallinity of silicon increases and the proportion of silicon decreases due to the excessive nitriding reaction, as the nitriding reaction is carried out for a long time of 1.5 hours at a high temperature of 1250°C. Prior art 2 (KR 10-2005-0016126 A) is a technology for coating a metallic silicon nucleus with an inert material such as silicon dioxide, silicon carbide, silicon nitride, or silicon oxynitride, and since the reaction proceeds for a long time of 30 minutes to 10 hours at a high temperature of 700 to 1000°C, it is difficult to solve the problem of increased silicon crystallinity and decreased silicon ratio as in Prior art 1. Figure 1 shows the XRD analysis results of the cathode active materials prepared in Examples 1-1 to 1-3 and Comparative Example 1 (Figure 1a), and the surface SEM image of the cathode active materials (Figure 1b). Figure 2 shows the XRD analysis results of the negative electrode active materials prepared in Examples 1-1 to 1-3 and Comparative Example 1 (Figure 2a), and a cross-sectional SEM image of the negative electrode active material (Figure 2b). Figure 3 shows the TGA analysis results of melamine (C₃H₆N₆ ) . Figures 4a to 4c are the XRD analysis results of the cathode active materials prepared in Examples 1-3 and Comparative Examples 4-1 and 4-2. 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 embo