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KR-102962061-B1 - COMPOSITE MATERIAL

KR102962061B1KR 102962061 B1KR102962061 B1KR 102962061B1KR-102962061-B1

Abstract

The present application provides a composite material, its use as a secondary battery electrode (e.g., a negative electrode), an electrode assembly and a secondary battery comprising the composite material, and a method for manufacturing the composite material. The present application provides an electrode having excellent lifespan characteristics, wherein the electrode is made of a silicon material, exhibits high capacity, and maintains a stable capacity even during repeated charging and discharging.

Inventors

  • 강호영
  • 김병진
  • 이철희
  • 유동우

Assignees

  • 주식회사 엘지화학

Dates

Publication Date
20260507
Application Date
20220113

Claims (15)

  1. A metal alloy foam comprising germanium and a metal alloy comprising a metal different from the germanium; and It includes silicon present on the surface or inside the above metal alloy foam, The above germanium is a composite material that allows silicon to be uniformly formed in a metal alloy foam.
  2. A composite material according to claim 1, wherein the metal other than germanium is one or more selected from the group consisting of stainless steel, aluminum, nickel, titanium, copper, silver, and cadmium.
  3. In claim 1, the metal alloy foam is a composite material containing germanium in an amount of 0.1 weight% to 20 weight%.
  4. In claim 3, the metal alloy foam is a composite material comprising a metal different from germanium in an amount of 500 to 3,000 parts by weight relative to 100 parts by weight of germanium.
  5. In claim 1, the metal alloy foam is a composite material having a porosity within the range of 30% to 90%.
  6. In claim 1, the metal alloy foam is a composite material having a thickness within the range of 0.5 μm to 1,000 μm.
  7. In claim 1, the silicon is a composite material in which a layer is formed by being deposited on the surface or inside of a metal alloy foam.
  8. A composite material according to claim 1, comprising silicon in an amount of 0.1 to 10 mg/ cm² .
  9. A metal alloy foam comprising germanium and a metal alloy comprising a metal different from the germanium; and It includes silicon present on the surface of the above metal alloy foam, The above germanium is a negative electrode for a secondary battery that allows silicon to be uniformly formed on a metal alloy foam.
  10. It includes an anode; a cathode and a separator between the anode and the cathode, and The above cathode is, A metal alloy foam comprising germanium and a metal alloy comprising a metal different from the germanium; and It includes silicon present on the surface of the above metal alloy foam, The above germanium is an electrode assembly that allows silicon to be uniformly formed on a metal alloy foam.
  11. A secondary battery comprising the electrode assembly of claim 10.
  12. A method for manufacturing a composite material comprising the step of forming silicon on the surface or inside a metal alloy foam containing germanium and a metal different from germanium, wherein the germanium allows silicon to be uniformly formed on the metal alloy foam.
  13. A method for manufacturing a composite material according to claim 12, wherein the metal alloy foam is manufactured by undergoing the step of sintering a precursor formed from a slurry comprising germanium powder and powder of a metal different from germanium under an oxygen partial pressure in the range of 1× 10⁻¹⁹ atm to 1× 10⁻¹⁵ atm.
  14. In claim 13, the method for manufacturing a composite material is performed by sintering at a temperature of 700°C to 1100°C.
  15. In claim 12, a method for manufacturing a composite material in which silicon is deposited on the surface or inside of a metal alloy foam by a plating method.

Description

Composite Material This application relates to composite materials and their uses. Rechargeable batteries, such as lithium-ion batteries, can be manufactured to be small and lightweight, have high energy density, and allow for repeated charging and discharging, so they are used in a wide variety of applications. The negative electrode plays a crucial role in the lifespan and capacity of secondary batteries. Currently, graphite is widely used as a negative electrode material, but silicon materials with high theoretical capacity are also being researched. Although silicon materials possess high theoretical capacity, they undergo repeated significant expansion and contraction during charging and discharging. This leads to problems such as the degradation of the active material over time, destruction of the electrode plate structure, and damage to the conductive paths within the electrode. Figure 1 is a diagram showing the results of a charge/discharge test for a coin cell in which the composite material of the present application is applied as a cathode. The present application will be specifically described below through examples and comparative examples, but the scope of the present application is not limited to the following examples. 1. Measurement of the average particle size of metal powder The average particle size of the metal powder (active material) was measured by the laser diffraction method, and the particle size corresponding to 50% of the cumulative volume in the volume-based particle size distribution curve (D50 particle size) was taken as the average particle size. The laser diffraction method was performed according to the KS L 1614 standard. Example 1. Manufacture of metal alloy foam Copper (Cu) powder with an average particle size (D50 particle size) in the range of about 60 μm and germanium (Ge) powder with an average particle size (D50 particle size) of about 0.3 μm were mixed in a weight ratio of 10:1 (Cu:Ge) and used as a metal component. Subsequently, the metal component was mixed with butanol and ethyl cellulose in a weight ratio of 1:0.9:0.1 (metal component:butanol:ethyl cellulose) to prepare a slurry. The above slurry was bar-coated onto a graphite foil with a thickness of about 200 μm to a thickness of about 400 μm. After bar-coating, the coating layer was dried by maintaining it at about 100°C for 30 minutes, and then sintered at 900°C for 2 hours in an H₂ / N₂ gas atmosphere to produce a metal alloy foam. During the sintering, the oxygen partial pressure ( pO₂ ) was controlled to about 2.24 x 10⁻¹⁸ atm. The pore size of the produced metal alloy foam was within the range of about 1 to 10 μm, and the porosity was about 72%. Manufacturing of electrodes Silicon was deposited on the metal alloy foam using an electrochemical plating method. Specifically, a solution was prepared by dissolving SiCl₄ in propylene carbonate at a concentration of approximately 0.5 M and then dissolving tetrabutylammonium chloride at a concentration of approximately 0.1 M. The prepared metal alloy foam was applied to the solution as the working electrode, a Pt plate as the counter electrode, and an Ag wire as the reference electrode. Plating was carried out for about 1 hour at a voltage of -1.5 V, followed by washing with propylene and then washing again with acetone to produce the electrode. During the above process, whether silicon was deposited on the metal alloy foam was confirmed through EDS (Energy Dispersive X-ray Spectroscopy) analysis. The amount of silicon deposited on the metal alloy foam was approximately 0.9 mg/ cm² . The amount of silicon is the value obtained by dividing the amount of silicon, calculated from the weight before and after silicon deposition, by the area of the metal alloy foam. In addition, the thickness and porosity of the silicon-deposited metal alloy foam were approximately the same as those of the metal alloy foam prior to silicon deposition. Comparative Example 1. Manufacturing of metal foam A metal foam was prepared in the same manner as in Example 1, except that only copper (Cu) powder with an average particle size (D50 particle size) within the range of about 60 μm was used as the metal component. The thickness and porosity of the prepared metal foam were the same as those of the metal alloy foam in Example 1. Manufacturing of electrodes Silicon was deposited on the metal foam prepared above in the same manner as in Example 1. Specifically, a solution was prepared by dissolving SiCl4 in propylene carbonate at a concentration of about 0.5 M and then dissolving tetrabutylammonium chloride at a concentration of about 0.1 M. The metal foam prepared above was applied to the solution as a working electrode, a Pt plate as a counter electrode, and an Ag wire as a reference electrode, and plating was carried out for about 1 hour at a voltage of -1.5 V, and then washed with propylene and then washed again with acetone to produce an electrode. Comparative Example 2. An electrode w