Search

CN-122000306-A - Method for manufacturing self-supporting film for lithium secondary battery anode and self-supporting film for lithium secondary battery anode manufactured by the method

CN122000306ACN 122000306 ACN122000306 ACN 122000306ACN-122000306-A

Abstract

The present disclosure relates to a method of manufacturing a self-supporting film for a negative electrode, including the steps of obtaining a negative electrode forming powder by mixing and grinding a negative electrode forming composition including a negative electrode active material, a conductive material, and a binder (S1), and forming a negative electrode active material layer by a film forming process using the negative electrode forming powder (S2). The binder includes a triblock copolymer including a soft block including aliphatic or alicyclic diene monomer units and exhibiting a rubber phase at room temperature, a first hard block connected to one end of the soft block including aromatic ring-containing ethylenically unsaturated monomer units and exhibiting a glass phase at room temperature, and a second hard block connected to the other end of the soft block including aromatic ring-containing ethylenically unsaturated monomer units and exhibiting a glass phase at room temperature, and an average particle diameter (D 50 ) of the binder contained in the anode-forming powder is smaller than an average particle diameter (D 50 ) of the binder contained in the anode-forming composition.

Inventors

  • LI BINGLONG
  • Cui Yixian
  • LIU XIAOMIN
  • ZHANG ZHURONG

Assignees

  • 现代自动车株式会社
  • 起亚株式会社

Dates

Publication Date
20260508
Application Date
20250520
Priority Date
20241105

Claims (17)

  1. 1. A method of manufacturing a self-supporting film for a negative electrode, the method comprising the steps of: s1 step of obtaining a negative electrode forming powder by mixing and grinding a negative electrode forming composition including a negative electrode active material, a conductive material, and a binder, and S2, forming a negative electrode active material layer by a film forming process using the negative electrode forming powder, Wherein the adhesive comprises a triblock copolymer comprising: A soft block comprising aliphatic or cycloaliphatic diene monomer units and exhibiting a rubber phase at room temperature; A first hard block connected to one end of the soft block and comprising ethylenically unsaturated monomer units containing aromatic rings and exhibiting a glassy phase at room temperature, and A second hard block connected to the other end of the soft block and comprising ethylenically unsaturated monomer units containing an aromatic ring and exhibiting a glassy phase at room temperature, and Wherein an average particle diameter D 50 of the binder contained in the anode-forming powder is smaller than an average particle diameter D 50 of the binder contained in the anode-forming composition.
  2. 2. The method of claim 1, wherein the binder included in the negative electrode-forming composition is spherical and has an average sphericity in the range of 0.8 to 1.0.
  3. 3. The method of claim 1, wherein the binder contained in the negative electrode-forming composition comprises particles having an average particle diameter D 50 in the range of 10 μιη to 50 μιη.
  4. 4. The method of claim 1, wherein step S1 is performed by a grinder, and wherein the RPM of the grinder is in the range of 15,000RPM to 25,000 RPM.
  5. 5. The method according to claim 1, wherein the binder contained in the anode-forming powder comprises particles having an average particle diameter D 50 in the range of 1 μm to 5 μm.
  6. 6. The method of claim 1, wherein the film forming process is performed in a dry process.
  7. 7. The method of claim 6, wherein the film forming process comprises calendaring, and wherein the calendaring is performed at a temperature equal to or higher than a first glass transition temperature and a second glass transition temperature corresponding to the first hard block and the second hard block, respectively.
  8. 8. The method of claim 1, wherein the first hard block and the second hard block each have a glass transition temperature in the range of 50 ℃ to 120 ℃, and wherein the soft block has a glass transition temperature in the range of-120 ℃ to-50 ℃.
  9. 9. The method of claim 1, wherein the aliphatic or cycloaliphatic diene monomer used to form the aliphatic or cycloaliphatic diene monomer unit is at least one selected from butadiene-based monomers, pentadiene-based monomers, and hexadiene-based monomers.
  10. 10. The method according to claim 1, wherein the aromatic ring-containing ethylenically unsaturated monomer used to form the aromatic ring-containing ethylenically unsaturated monomer unit is at least one selected from the group consisting of styrene-based monomers and aromatic (meth) acrylic monomers.
  11. 11. A self-supporting film for a negative electrode, the self-supporting film comprising: a plurality of negative electrode active materials, a plurality of conductive materials and a binder, Wherein the adhesive comprises a triblock copolymer comprising: a soft block comprising aliphatic or cycloaliphatic diene monomer units and exhibiting a rubber phase at room temperature, A first hard block connected to one end of the soft block and comprising ethylenically unsaturated monomer units containing aromatic rings and exhibiting a glassy phase at room temperature, and A second hard block connected to the other end of the soft block, comprising ethylenically unsaturated monomer units containing aromatic rings, and exhibiting a glassy phase at room temperature, Wherein the binder is in a discontinuous columnar shape, connects one of the plurality of anode active materials or one of the plurality of conductive materials to another of the plurality of anode active materials or another of the plurality of conductive materials, and Wherein the average value of the width of the adhesive perpendicular to the length direction is 50nm or less.
  12. 12. The self-supporting film according to claim 11, wherein when the self-supporting film for a negative electrode is irradiated with an electron beam of 5.0kV for at least 1 second to obtain a scanning electron microscope SEM image, a surface of the negative electrode active material or a surface of the conductive material contains a molten structure having an average value of widths perpendicular to a length direction of 30nm or less, and Wherein the melt structure comprises the triblock copolymer.
  13. 13. The self-supporting film of claim 11, wherein the first hard block and the second hard block each have a glass transition temperature in the range of 50 ℃ to 120 ℃, and Wherein the soft block has a glass transition temperature in the range of-120 ℃ to-50 ℃.
  14. 14. The self-supporting film of claim 11, wherein the aliphatic or cycloaliphatic diene monomer used to form the aliphatic or cycloaliphatic diene monomer unit is at least one selected from butadiene-based monomers, pentadiene-based monomers, and hexadiene-based monomers.
  15. 15. The self-supporting film of claim 11, wherein the aromatic ring-containing ethylenically unsaturated monomer used to form the aromatic ring-containing ethylenically unsaturated monomer unit is selected from at least one of styrene-based monomers and aromatic (meth) acrylic monomers.
  16. 16. A negative electrode for a lithium secondary battery, comprising: current collector, and The self-supporting film for a negative electrode according to any one of claims 11 to 15, which is provided on the current collector.
  17. 17. A lithium secondary battery comprising: the negative electrode for a lithium secondary battery according to claim 16; Positive electrode for lithium secondary battery, and An electrolyte.

Description

Method for manufacturing self-supporting film for lithium secondary battery anode and self-supporting film for lithium secondary battery anode manufactured by the method Cross Reference to Related Applications The present application claims priority from korean patent application No.10-2024-0155653 filed on month 11 and 5 of 2024 to korean intellectual property office, the entire contents of which are incorporated herein by reference. Technical Field The present disclosure relates to a method of manufacturing a self-supporting film for a negative electrode of a lithium secondary battery by using a triblock copolymer including a soft block and a hard block, and a self-supporting film for a negative electrode of a lithium secondary battery manufactured by the method. Background Since the first commercialization of lithium secondary batteries in the nineties of the twentieth century, lithium secondary batteries have been widely used and continue to receive attention as the most studied energy storage systems. Since the lithium secondary battery has higher driving voltage, higher energy density, lower self-discharge rate, higher rate capability and longer cycle stability, it is suitable as an energy source for electric vehicles. However, lithium secondary batteries applied to electric vehicles face three main problems of stability, running time and cost. Stability and operation time can be solved by all-solid-state batteries, but cost is one factor impeding the wide use of lithium secondary batteries. Accordingly, many researches and researches are directed to reducing the cost of the lithium secondary battery. Reducing the energy consumption required for manufacturing or increasing the electrode thickness is one of the most effective methods for reducing the manufacturing cost of lithium secondary batteries. According to the conventional electrode manufacturing technique, a slurry prepared by mixing an electrode active material, a polymer binder, and a conductive additive with water or an organic solvent is cast onto a current collector, and the resultant product is dried and pressed to form an electrode. In this case, the energy required for preparing the slurry and coating the current collector accounts for 50% of the energy consumption in the entire manufacturing process. Accordingly, research and exploration have been conducted on a process of manufacturing an electrode without using a solvent dry method in order to reduce manufacturing costs of a lithium secondary battery. Typically, as a dry electrode manufacturing process, there has been a technology of manufacturing a positive electrode of a lithium secondary battery using a dry method of Polytetrafluoroethylene (PTFE). PTFE can have the Lowest Unoccupied Molecular Orbital (LUMO) energy level and therefore readily accept electrons. Thus, PTFE is electrochemically unstable in a negative potential environment. Therefore, the lithium secondary battery anode manufactured using PTFE as a binder exhibits poor cycle stability. In addition, when the negative electrode is manufactured using PTFE, the PTFE binder is decomposed during initial charging, resulting in a decrease in initial efficiency of the lithium secondary battery. Although a great deal of research and exploration has been made on the technology of dry-process manufacturing electrodes, there is still insufficient development of dry-process anode manufacturing technology for manufacturing an anode having excellent physical properties in terms of formability, electrochemical stability, or tensile strength. Therefore, research and development of this technology is required. Disclosure of Invention The present disclosure is directed to solving the above-described problems occurring in the prior art, while fully retaining the advantages achieved by the prior art. An aspect of the present disclosure provides a self-supporting film for a lithium secondary battery, which is easy to form, can be stably maintained even at a negative potential, and is firmly bonded to a negative electrode active material by applying a binder including a triblock copolymer including a hard block contributing to achieving excellent mechanical properties and a soft block having flexibility, and is firmly bonded to a negative electrode active material and a conductive material by exhibiting excellent tensile strength and forming a three-dimensional network, a method of manufacturing the self-supporting film, a negative electrode for a lithium secondary battery including the negative electrode self-supporting film, and a lithium secondary battery. The technical problems to be solved by the present disclosure are not limited to the above-described problems, and any other technical problems not mentioned herein will be clearly understood by those skilled in the art to which the present disclosure pertains from the following description. According to one aspect of the present disclosure, there is provided a method of manufacturing a