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KR-20260064622-A - Method for manufacturing negative electrode active material for secondary batteries

KR20260064622AKR 20260064622 AKR20260064622 AKR 20260064622AKR-20260064622-A

Abstract

The object of the present invention is to provide a method for manufacturing a negative electrode active material comprising a silicon/carbon composite, wherein the negative electrode active material is manufactured to have high sphericity and a low sphericity SPAN value. One embodiment of the present invention provides a method for manufacturing a negative electrode active material for a secondary battery, comprising: a) a step of preparing a silicon/carbon composite precursor by introducing silicon-based particle powder and amorphous carbon precursor powder into a spheroidizing device and then spheroidizing them by a mechanofusion method at 3,000 to 10,000 rpm for 5 to 60 minutes; and b) a step of preparing a silicon/carbon composite by heat treating the silicon/carbon composite precursor. Accordingly, a negative electrode active material having high sphericity and low sphericity SPAN values can prevent localized lithium concentration increase due to a uniform current density distribution and enable rapid insertion/extraction of lithium ions, thereby providing excellent charge/discharge rate characteristics.

Inventors

  • 이총민
  • 서유경
  • 채태성
  • 전민영
  • 이동욱

Assignees

  • 주식회사 에코프로비엠

Dates

Publication Date
20260507
Application Date
20251030
Priority Date
20241031

Claims (7)

  1. a) a step of preparing a silicon/carbon composite precursor by introducing silicon-based particle powder and amorphous carbon precursor powder into a spheroidizing device and then spheroidizing them by a mechanofusion method at 3,000 to 10,000 rpm for 5 to 60 minutes; and b) a step of heat-treating a precursor of the silicon/carbon composite to produce a silicon/carbon composite; comprising a method for manufacturing a negative electrode active material for a secondary battery.
  2. In paragraph 1, A method for manufacturing a negative electrode active material for a secondary battery, wherein step a) involves introducing the silicon-based particle powder and the amorphous carbon precursor powder into the spheroidizing device in a weight ratio of 60:40 to 80:20.
  3. In paragraph 1, A method for manufacturing a negative electrode active material for a secondary battery, wherein step a) above involves spheroidizing by a mechanofusion method at 5,000 to 10,000 rpm for 5 to 30 minutes in the spheroidizing device.
  4. In paragraph 1, In step a) above, the silicon-based particles are, i) The average particle size (Dv50) is 200 to 600 nm, and ii) A method for manufacturing a negative electrode active material for a secondary battery having a plate-like and/or needle-like shape.
  5. In paragraph 1, A method for manufacturing a negative electrode active material for a secondary battery, wherein step b) above involves heat treatment at 800 to 1,100 ℃ for 1 to 20 hours under an inert atmosphere.
  6. In paragraph 1, A method for manufacturing a negative electrode active material for a secondary battery, wherein the method comprises manufacturing the silicon/carbon composite such that i) an average sphericity of 0.9 or higher and ii) a sphericity SPAN (C90-C10)/C50 value of 0.10 or lower.
  7. In paragraph 1, The above method for manufacturing the negative electrode active material is, A method for manufacturing a negative electrode active material for a secondary battery, wherein the ratio (D1/D2) of the average particle size (Dv50) (D1) of the silicon-based particles to the average particle size (Dv50) (D2) of the silicon/carbon composite is 0.015 to 0.1.

Description

Method for manufacturing negative electrode active material for secondary batteries The present invention relates to a method for manufacturing a negative electrode active material for a secondary battery. Batteries store electricity by using materials capable of electrochemical reactions at the positive and negative electrodes. Representative examples of such batteries include lithium-ion or sodium-ion batteries, which store electrical energy based on the difference in chemical potential when lithium ions are intercalated or deintercalated at the positive and negative electrodes. The above secondary battery is manufactured by using a material capable of reversible intercalation/deintercalation of lithium ions as the active material for the positive and negative electrodes, and by filling an organic electrolyte or a polymer electrolyte between the positive and negative electrodes. Carbon-based materials, such as natural graphite and artificial graphite, which are representative materials used as negative electrode active materials for secondary batteries, have excellent cycle life characteristics but have a low theoretical capacity of about 372 mAh/g. As there is a growing demand for higher capacity secondary batteries, such as medium and large-sized secondary batteries, inorganic negative electrode materials such as silicon (Si), germanium (Ge), tin (Sn), or antimony (Sb), which have a capacity of 500 mAh/g or more and can replace them, are attracting attention. Among inorganic anode materials, silicon-based anode materials exhibit a relatively large amount of alkali metal (lithium, sodium, or potassium) binding. However, silicon-based anode materials can undergo pulverization due to significant volume changes during the insertion or extraction of alkali metals. The aggregation of these pulverized particles can cause the anode active material to detach electrically from the current collector, leading to a loss of reversible capacity under repeated cycles. For this reason, despite the advantages of high capacity, silicon-based anode materials and secondary batteries containing them face significant difficulties in commercialization due to drawbacks such as low cycle life characteristics and capacity retention rates. Accordingly, there is a need to develop silicon-based anode active materials that can effectively control volume changes during the charging and discharging process of secondary batteries and increase the lithium ion conductivity of the anode. Figures 1 to 5 are SEM images of the negative electrode active materials prepared in Comparative Examples 1 to 2 and Examples 1 to 3, respectively. Figures 6a and 6b are SEM images of silicon (primary particles, Dv50: 400 nm, plate-like) and petroleum-based pitch used in Examples 1 to 3, respectively. FIG. 7 is a graph showing the change in the circularity distribution of cathode active material particles prepared in Comparative Examples 1 to 2 and Examples 1 to 3. FIG. 8 is a graph showing i) the relationship between BET specific surface area according to the change in sphericity and ii) the relationship between BET specific surface area according to the change in sphericity SPAN of the negative electrode active materials prepared in Comparative Examples 1 to 2 and Examples 1 to 3. FIGS. 9 to 13 are SEM images of cross-sections of silicon/carbon composites included in the cathode active materials prepared in Examples 1 to 3 and Comparative Examples 1 to 2, and graphs (EDS-line scanning) showing changes in the content of elements (silicon, carbon) within the cross-section of the particles through EDS analysis in the direction indicated by arrows in the SEM images. 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