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KR-102963238-B1 - CATHOD MATERIAL FOR LITHIUM-SULFUR BATTERY AND LITHIUM-SULFUR BATTERY INCLUDING THE SAME

KR102963238B1KR 102963238 B1KR102963238 B1KR 102963238B1KR-102963238-B1

Abstract

The present invention relates to a carbon composite for use in a positive electrode of a lithium-sulfur battery and a method for manufacturing the same, wherein the carbon composite comprises a porous carbon substrate and metal particles formed on at least a portion of the surface of the porous carbon substrate, and the metal particles are in a spiky shape.

Inventors

  • 박성효
  • 김희탁
  • 이창훈
  • 김일주

Assignees

  • 주식회사 엘지에너지솔루션
  • 한국과학기술원

Dates

Publication Date
20260511
Application Date
20231222
Priority Date
20221227

Claims (15)

  1. A carbon composite for the positive electrode of a lithium-sulfur battery comprising a sulfur-based material as an active material, porous carbon substrate, and It includes metal particles formed on at least a portion of the surface of the porous carbon substrate, and The above metal particles have catalytic activity for the kinetic activity of the redox reaction of the above sulfur-based material, and are in a spiky form, A carbon composite characterized in that, when a position adjacent to the surface of a porous carbon substrate on which the metal particles are formed is designated as the lower position and a position extending outward from the surface of the porous carbon substrate is designated as the upper position, the needle-shaped metal particles have a shape in which the radius of the upper position is smaller than the radius of the lower position and the ratio of the total length to the radius of the lower position (L/D) is 1 or greater.
  2. delete
  3. In claim 1, A carbon composite characterized in that the above-mentioned needle-shaped metal particles have a shape in which the ratio of the total length to the radius of the lower portion (L/D) is 5 or more.
  4. In claim 1, A carbon composite characterized by the upper radius (D 50 ) of the above needle-shaped metal particles being 100 nm or less.
  5. In claim 1, A carbon composite characterized by the lower radius (D 50 ) of the above needle-shaped metal particles being 100 nm to 1,000 nm.
  6. In claim 1, A carbon composite characterized by the total length (D 50 ) of the above-mentioned needle-shaped metal particles being 1 μm to 10 μm.
  7. In claim 1, A carbon composite characterized in that the metal particles include transition metal particles.
  8. In claim 1, A carbon composite characterized in that the porous carbon substrate comprises carbon fiber cloth, carbon nanotube (CNT), graphene, graphene oxide (GO), reduced graphene oxide (rGO), carbon black, graphite, graphite nanofiber (GNF), carbon nanofiber (CNF), activated carbon fiber (ACF), activated carbon, fullerene, or two or more of these materials.
  9. A carbon composite according to any one of claims 1 and claims 3 to 8; and an active material; comprising, A positive electrode for a lithium-sulfur battery characterized by including a sulfur-based material as the active material.
  10. In claim 9, A positive electrode for a lithium-sulfur battery, characterized in that the above-mentioned sulfur-based material is coated on all or part of the surface of the above-mentioned carbon composite.
  11. The electrode assembly comprises an anode, a cathode, and a separator interposed between the anode and the cathode; and an electrolyte; and A lithium-sulfur battery characterized in that the anode is the anode according to claim 9.
  12. In claim 11, A lithium-sulfur battery characterized in that the electrolyte comprises LiBr, LiCl, LiI, LiTf, or a mixture of two or more of these as a lithium salt.
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  14. A method for manufacturing a carbon composite according to any one of claims 1 and claims 3 to 8, wherein A step of preparing a metal particle precursor solution by mixing metal chloride hydrate, ammonium fluoride, and urea; and A method for manufacturing a carbon composite, characterized by comprising the step of forming needle-shaped metal particles on at least a portion of the surface of a porous carbon substrate through a hydrothermal reaction while the porous carbon substrate and the metal particle precursor solution are in contact.
  15. In claim 14, A method for manufacturing a carbon composite, characterized in that the above-mentioned metal chloride hydrate is a transition metal chloride hydrate.

Description

Cathode material for lithium-sulfur battery and lithium-sulfur battery including the same The present invention relates to a cathode material for a lithium-sulfur battery and a lithium-sulfur battery including the same. A lithium-sulfur battery is a battery system that uses a sulfur-based material with S-S (sulfur-sulfur) bonds as the positive electrode active material and lithium metal as the negative electrode active material. Sulfur, the main material of the positive electrode, has the advantages of being abundant globally, non-toxic, and having a low weight per atom. As the application areas of secondary batteries expand to electric vehicles (EVs) and energy storage systems (ESS), lithium-sulfur battery technology, which can theoretically achieve a high energy storage density (~2,600 Wh/kg) compared to lithium-ion secondary batteries with a relatively low energy storage density (~250 Wh/kg), is gaining attention. In a lithium-sulfur battery, during discharge, lithium, which is the negative electrode active material, releases electrons and is oxidized as it ionizes into lithium cations, while sulfur-based material, which is the positive electrode active material, is reduced as it accepts electrons. Here, through the reduction reaction of the sulfur-based material, the SS bond accepts two electrons and is converted into a sulfur anion. The lithium cations generated by the oxidation reaction of lithium are transferred to the positive electrode through the electrolyte, and combine with the sulfur anions generated by the reduction reaction of the sulfur-based compound to form a salt. Specifically, sulfur before discharge has a cyclic S8 structure, which is converted into lithium polysulfide ( Li₂Sx ) through a reduction reaction, and is completely reduced to produce lithium sulfide ( Li₂S ). At this time, due to the phenomenon where lithium sulfide formed accumulates on the surface of the electrode of the lithium-sulfur battery, the lithium-sulfur battery is currently exhibiting only a discharge capacity that falls short of its theoretical capacity. In particular, the automotive market, which has recently been a prominent application field for batteries, demands the development of batteries capable of driving long distances on a single charge. Therefore, lithium-sulfur batteries also need to be developed to meet energy consumption standards to the extent that long-distance driving is possible on a single charge. Accordingly, in order to commercialize lithium-sulfur batteries, it is necessary to develop technology to resolve the passivation phenomenon caused by lithium sulfide accumulating on the electrodes. The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the aforementioned description; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. Figure 1 is the result of evaluating the lifespan characteristics of a battery according to Experimental Example 1 in this specification. Figure 2 is the result of evaluating the discharge capacity of a battery according to Experimental Example 1 in this specification. FIG. 3 is the result of evaluating the resistance curve of a battery according to Experimental Example 2 in this specification. In FIG. 3, the graph of Comparative Example 4 represents 2 Hz. Figure 4 is the result of confirming the shape of lithium sulfide electrodeposited on the electrodes of Example 2 and Example 3 according to an experiment within this specification. Figure 5 is the result of confirming the shape of lithium sulfide electrodeposited on the electrodes of Example 2 and Example 3 according to an experiment within this specification. Figure 6 is the result of XPS analysis of metal particles after lithium sulfide was electrodeposited on the electrodes of Example 2 and Example 3 according to an experiment within this specification. FIG. 7 is a scanning electron microscope image of the surface image of the electrode of Comparative Example 5 according to an experiment within this specification. Figure 8 is the result of confirming the shape of lithium sulfide electrodeposited on the electrode of Comparative Example 5 according to one experiment within the present specification. The present invention will be described in more detail below. Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Throughout this specification, when a part is described as "comprising" or "having" a certain component, unless specifically stated otherwise, this means that it doe