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KR-20260062548-A - METHOD OF PREPARING METAL-DOPED POROUS SILICON COMPOSITES THROUGH GALVANIC SUBSTITUTION, AND SECONDARY BATTERY ANODE PREPARED USING THE SAME

KR20260062548AKR 20260062548 AKR20260062548 AKR 20260062548AKR-20260062548-A

Abstract

The present invention relates to a method for manufacturing a porous silicon composite and a secondary battery negative electrode comprising the porous silicon composite manufactured according to the same as a negative electrode active material. The porous silicon composite according to the present invention is doped with a highly conductive transition metal, and by increasing the degree of carbonization of the carbon coating through a catalytic reaction by the doped transition metal, the stability of the porous silicon particles and the cycle characteristics of the lithium-ion battery comprising the porous silicon composite are improved, thereby enabling high Coulomb efficiency.

Inventors

  • 류재건
  • 권진용

Assignees

  • 서강대학교산학협력단

Dates

Publication Date
20260507
Application Date
20241029

Claims (13)

  1. (a) dispersing a silicon alloy precursor in an etching solution containing a highly conductive transition metal precursor, etching, and then grinding to obtain porous silicon alloy particles doped with a highly conductive transition metal; and (b) obtaining a porous silicon composite additionally coated with carbon material by mixing the above-mentioned doped porous silicon alloy particles with a carbon coating precursor and heat treating. A method for manufacturing a porous silicon composite comprising
  2. In Article 1, The above silicon alloy precursor is represented as A x Si y (x+y=100, 12 ≤ y ≤ 40) or A p B q Si r (p+q+r=100, 12 ≤ r ≤ 40), and Here, A is Al or Mg, and B is Fe, Co, or Sn, and Method for manufacturing a porous silicon composite.
  3. In Article 1, A method for manufacturing a porous silicon composite, wherein the highly conductive transition metal included in the above highly conductive transition metal precursor has an electrical conductivity of 1.0 × 10⁷ S/cm or more.
  4. In Article 1, A method for manufacturing a porous silicon composite, wherein the above-mentioned high-conductivity transition metal precursor is a salt comprising one or more high-conductivity transition metals selected from Ni, Co, Cu, Ag, and Mn.
  5. In Article 1, A method for manufacturing a porous silicon composite, wherein the etching solution comprises an acidic etching solution.
  6. In Article 1, A method for manufacturing a porous silicon composite, wherein the etching solution comprises 0.1 to 5 parts by weight of a highly conductive transition metal precursor per 100 parts by weight of a silicon alloy precursor.
  7. In Article 1, A method for manufacturing a porous silicon composite, wherein the etching of (a) above is performed by stirring for 2 to 4 hours under an ice bath.
  8. In Article 1, A method for manufacturing a porous silicon composite, further comprising the steps of removing the etching solution and drying after the etching of (a) above.
  9. In Article 1, A method for manufacturing a porous silicon composite, wherein the grinding of (a) above is performed by one or more methods selected from a ball mill, a rod mill, a crushing roll, a hammer mill, a disc friction mill, and an air jet mill.
  10. In Article 1, A method for manufacturing a porous silicon composite, wherein the carbon coating precursor is one or more selected from polymer-based carbonization precursors, pitch-based carbonization precursors, liquid-phase carbonization precursors, or gas-phase carbonization precursors.
  11. In Article 1, A method for manufacturing a porous silicon composite, wherein the carbon coating precursor of (b) above is used in an amount of 5 to 200 parts by weight per 100 parts by weight of the doped silicon alloy particles.
  12. In Article 1, A method for manufacturing a porous silicon composite, wherein the heat treatment of (b) above is performed at a temperature of 800°C to 1,000°C.
  13. A secondary battery negative electrode comprising a porous silicon composite manufactured by the manufacturing method according to claim 1 as a negative electrode active material.

Description

Method of preparing metal-doped porous silicon composites through galvanic substitution and secondary battery anode prepared using the same The present invention relates to a method for manufacturing a porous silicon composite and a secondary battery negative electrode comprising the porous silicon composite manufactured according to the same as a negative electrode active material. Recently, as the demand for electric energy to replace fossil fuels has surged, lithium-ion batteries, which possess high energy density and long lifespan, are being utilized in various fields such as electric vehicles, drones, and electronic devices. However, conventional lithium-ion batteries still fall short of the energy densities required by daily life and industry; consequently, there is growing interest in anode active materials that surpass the low capacity per unit mass (372 mAh/g) of graphite, which is currently used as the anode active material in conventional lithium-ion batteries. Consequently, the development of anode materials (such as silicon and tin) that form alloy reactions with lithium, which possesses high energy density, is underway. Among the anode material candidates, silicon, which exhibits high unit energy capacity, undergoes changes in its crystal structure during the charging and discharging process, resulting in a volume change of up to 300%. This entails stability-related problems, such as detachment from the electrode, the formation of unstable interfaces, and mechanical crushing. To solve these issues, technology to control the structure of silicon is required. Regarding silicon structure control technology, research has been conducted on porous silicon among various silicon structures, as it can efficiently relieve internal stress and suppress cracking within particles during volume expansion. However, porous silicon presents several challenges, including a complex manufacturing process, high production costs, difficulty in doping desired metals into the silicon, and difficulty in synthesizing it in large quantities. Furthermore, due to its large specific surface area, porous silicon suffers from disadvantages such as reduced initial Coulomb efficiency and the occurrence of side reactions; consequently, processes to reduce the specific surface area by treating the surface, such as introducing a carbon layer, are required. Therefore, for the commercialization of lithium-ion batteries, technology is needed to dope elements into porous silicon anode materials and modify their surfaces through simpler processes. Conventional porous silicon processing technology has focused on relieving internal stress by controlling pore size and morphology through multiple heat treatment steps. Consequently, there is currently a lack of technology for improving silicon performance by doping it with elements. Among these, conventional transition metal doping techniques necessarily involve high-energy ball milling and high-temperature heat treatment steps. Consequently, large-scale synthesis of porous silicon is difficult, manufacturing costs are high due to excessive energy consumption, and excessive byproducts with harmful environmental effects are generated. Furthermore, transition metals are doped only onto the exterior of the silicon, preventing uniform doping into the interior. Additionally, when transition metals are doped into silicon according to conventional technology, the nanostructured silicon is unable to withstand the high energy of the ball milling step, leading to structural destruction and other problems. Moreover, carbon modification is performed inefficiently because additional manufacturing steps are required to control the morphology of the carbon coating layer for surface modification, such as altering carbon precursors or adjusting heat treatment conditions. To solve the aforementioned problems, there is a need for a porous silicon manufacturing technology that improves silicon properties by doping silicon with elements in a simpler manufacturing process, while simultaneously modifying the properties of the carbon coating layer. FIG. 1 is a flowchart showing the steps of a method for manufacturing a porous silicon composite according to embodiments of the present invention and a conventional method for manufacturing a porous silicon composite. FIG. 2 is a schematic diagram showing the structure of a porous silicon composite according to a method for manufacturing a porous silicon composite according to embodiments of the present invention. FIGS. 3a and 3b are a graph showing the X-ray diffraction (XRD) results of Examples 1 and 2 and Comparative Examples 1 and 2 in one embodiment of the present invention (Fig. 3a), and an X-ray diffraction analysis graph of Examples 1 and 2 and Comparative Examples 1 and 2 enlarged from the 27.5° to 29.5° portion in FIG. 3a (Fig. 3b). FIGS. 4a to 4d are scanning electron microscope (SEM) images of Comparative Example 1 of the present invention (Fig. 4a), Compar