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KR-20260064642-A - AN ELECTRODE, A MANUFACTURING METHOD THEREOF, AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

KR20260064642AKR 20260064642 AKR20260064642 AKR 20260064642AKR-20260064642-A

Abstract

An electrode is provided, a method for manufacturing the same, and a lithium secondary battery comprising the same, the electrode current collector; and an electrode active material layer formed on at least one surface of the electrode current collector, wherein the electrode active material layer comprises an electrode active material and a first conductive material-first binder composite, wherein the first conductive material comprises carbon nanotubes and the first binder has a composite viscosity of 1,500 Pa·s or less at 170°C and 0.1 Hz.

Inventors

  • 이태희
  • 문성식
  • 신정민
  • 한성재

Assignees

  • 주식회사 엘지화학

Dates

Publication Date
20260507
Application Date
20251031
Priority Date
20241031

Claims (17)

  1. The electrode current collector; and an electrode active material layer formed on at least one surface of the electrode current collector, comprising The above electrode active material layer comprises an electrode active material and a first conductive material-first binder composite, and The above first conductive material includes carbon nanotubes, and An electrode characterized in that the first binder has a composite viscosity of 1,500 Pa·s or less at 170°C and 0.1 Hz.
  2. In paragraph 1, An electrode characterized in that the first binder has a composite viscosity of 0.01 Pa·s to 1,500 Pa·s at 170°C and 0.1 Hz.
  3. In paragraph 1, An electrode characterized in that the first conductive material-first binder composite comprises a first binder and a first conductive material bonded to the surface of the first binder.
  4. In paragraph 1, An electrode characterized in that the first binder comprises a polyolefin-based polymer.
  5. In paragraph 1, An electrode characterized in that the first binder comprises polyethylene, polypropylene, polybutylene, polypentene, or two or more of these.
  6. In paragraph 1, An electrode characterized by the weight-average molecular weight of the first binder being 5,000 g/mol to 200,000 g/mol.
  7. In paragraph 1, An electrode characterized in that the weight ratio of the first conductive material and the first binder in the first conductive material-first binder composite is 1:99 to 30:70.
  8. In paragraph 1, An electrode characterized in that the electrode active material layer further comprises one or more of a second conductive material and a second binder.
  9. In paragraph 8, An electrode characterized in that the second binder comprises polytetrafluoroethylene.
  10. In paragraph 8, An electrode characterized in that the weight ratio of the first binder and the second binder is 10:90 to 90:10.
  11. In paragraph 1, An electrode characterized in that the electrode active material layer comprises 90 to 80 parts by weight of an electrode active material and 3 to 20 parts by weight of a first conductive material-first binder composite.
  12. In paragraph 8, An electrode characterized in that the electrode active material layer comprises 90 to 80 parts by weight of an electrode active material, 0.5 to 10 parts by weight of a first conductive material-first binder composite, 0.5 to 5 parts by weight of a second binder, and 0.5 to 5 parts by weight of a second conductive material.
  13. A lithium secondary battery comprising a positive electrode; a negative electrode; a separator disposed between the positive electrode and the negative electrode; and an electrolyte, A lithium secondary battery characterized in that at least one of the above positive and negative electrodes is an electrode according to any one of claims 1 to 12.
  14. A step of preparing a mixture by dry mixing and kneading the electrode active material and the first conductive material-first binder composite without a solvent; A step of grinding the above mixture; A step of manufacturing an electrode sheet by feeding the above-mentioned crushed product between a plurality of rolls and calendering it; and A method for manufacturing an electrode of claim 1, comprising the step of laminating the electrode sheet on at least one surface of a current collector.
  15. In Paragraph 14, The above first conductive material-first binder composite A method for manufacturing an electrode characterized by forming a first conductive material and a first binder by dry fusing them so that the first conductive material is bonded to the surface of the first binder.
  16. In paragraph 15, A method for manufacturing an electrode characterized by performing the above dry fusion at a speed of 1,000 to 9,000 rpm for a period of 5 to 60 minutes.
  17. In Paragraph 14, A method for manufacturing an electrode, characterized in that the step of preparing the above mixture includes a step of mixing and kneading dryly without a solvent, additionally including one or more of a second conductive material and a second binder in addition to the electrode active material and the first conductive material-first binder composite.

Description

Electrode, manufacturing method thereof, and lithium secondary battery comprising the same The present invention relates to an electrode, a method for manufacturing the same, and a lithium secondary battery including the same. Specifically, the invention relates to an electrode having excellent electrochemical performance with improved conductive material dispersibility and binder flowability, a method for manufacturing the same, and a lithium secondary battery including the same. This application claims priority based on Korean Application No. 10-2024-0152842 filed on October 31, 2024, and all contents disclosed in the specification of said application are incorporated into this application. Recently, interest in energy storage technology has been steadily increasing. As application fields expand to include mobile phones, camcorders, laptop PCs, and even electric vehicles, there is a growing demand for higher energy density in batteries used as power sources for these electronic devices. Lithium-ion batteries are the best candidates to meet these demands, and active research is currently underway in this area. Such lithium secondary batteries generally include a positive electrode made of lithium metal oxide, a negative electrode made of carbon material, an electrolyte containing a lithium salt and an organic solvent, and a separator interposed between the positive and negative electrodes to electrically insulate them. Currently, the positive electrode of a lithium secondary battery is manufactured by mixing an active material, a conductive material, and an N-methyl-2-pyrrolidone (NMP) solvent with poly(vinylidene fluoride) (PVdF) as a binder to form a slurry, which is then coated onto a current collector. However, halogen-based PVdF binders have problems such as gas generation or electrode delamination during charging and discharging under high temperature and high voltage. Additionally, NMP, which is used as a solvent, is harmful to the environment and requires recovery facilities. Furthermore, it has a high boiling point of 200°C, making it difficult to ensure processability. Moreover, defects such as cracks may occur in the active material layer as the solvent evaporates during the drying process of the slurry coated on the current collector. Recently, research on manufacturing solvent-free dry electrodes is actively underway. Dry electrodes are manufactured by thoroughly mixing active materials, conductive agents, and binders dry without solvents. Among these, carbon black is used as the conductive agent for manufacturing dry electrodes; however, the reality is that the use of carbon nanotubes, such as MWCNTs with excellent conductivity, is limited due to the difficulty of dispersion. In addition, the binder used to bind the electrode active material and the conductive material acts as a resistor within the electrode. Therefore, there is still a need to develop electrodes with improved electrical conductivity characteristics by improving the dispersibility of linear conductive materials, such as carbon nanotubes, in dry electrodes and reducing the resistance of the binder. 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 description of the invention; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. Meanwhile, the shape, size, scale, or ratio of elements in the drawings included in this specification may be exaggerated to emphasize a clearer explanation. Figure 1 is a photograph of the first conductive material-first binder composite of Example 2 before and after preparation. Figure 2 is a graph showing the results of powder resistance evaluation of the first conductive material-first binder composite prepared in Examples 1, 2, and 3, carbon black, and multi-walled carbon nanotube (MWCNT) conductive material alone. Hereinafter, the present invention will be described in detail with reference to the drawings. Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Therefore, the embodiments described in this specification and the configurations described in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application. Furthermore, throughout the specification, when a part is described as "include, comprise," "hav