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EP-4496021-B1 - METHOD OF MANUFACTURING DRY-PROCESSED ELECTRODE AND OBTAINED DRY-PROCESSED ELECTRODE

EP4496021B1EP 4496021 B1EP4496021 B1EP 4496021B1EP-4496021-B1

Inventors

  • ZHOU, Siqiuyue
  • ZHAO, Linyan
  • JI, Yajuan
  • ZHAO, Ruirui

Dates

Publication Date
20260513
Application Date
20240719

Claims (15)

  1. A method of manufacturing a dry-processed electrode, characterized by comprising steps of: formulating a dispersion binder and an aqueous binder into a glue liquid; dry-mixing an active material, a conductive agent, and a main binder to obtain a first dry material; adding the glue liquid to the first dry material for dispersion, and performing a drying treatment to obtain a second dry material; pulverizing the second dry material to form a binder-fibrillized powder; and pressing the powder to obtain a dry-processed electrode; wherein the step of formulating the dispersion binder and the aqueous binder into the glue liquid and the step of dry-mixing the active material, the conductive agent and the main binder to obtain the first dry material are in a non-sequential order.
  2. The method of claim 1, characterized in that the dispersion binder comprises a small molecule polymer binder; wherein the small molecule polymer binder is any one or a combination of at least two of polyvinylpyrrolidone, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, or polyethylene glycol; and preferably, the aqueous binder comprises any one or a combination of at least two of a polyacrylic acid or a salt of the polyacrylic acid or a copolymer of the polyacrylic acid, carboxymethyl cellulose or a salt of the carboxymethyl cellulose or a copolymer of the carboxymethyl cellulose, an alginate, an SBR emulsion, or PEG.
  3. The method of claim 1 or 2, characterized in that a mass ratio of the dispersion binder to the aqueous binder in the glue liquid is (1 to 3):1; preferably, a total mass concentration of binders in the glue liquid is 5wt% to 30wt%; preferably, the step for formulating the dispersion binder and the aqueous binder into the glue liquid comprises: formulating the dispersion binder and the aqueous binder into a liquid A and a liquid B respectively, each having a mass concentration of 5wt% to 30wt%; and mixing the liquid A and the liquid B, and adjusting the mass concentration to 5wt% to 30wt% using a solvent to obtain the glue liquid; and preferably, the solvent comprises water.
  4. The method of any one of claims 1 to 3, characterized in that the main binder comprises polytetrafluoroethylene and/or polytetrafluoroethylene derivative; preferably, the polytetrafluoroethylene derivative comprises any one or a combination of at least two of a tetrafluoroethylene-hexafluoropropylene copolymer, an ethylene-tetrafluoroethylene copolymer, or a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer; preferably, the conductive agent comprises any one or a combination of at least two of conductive carbon black, carbon nanofibers, carbon nanotubes, or graphene; preferably, when the dry-processed electrode is a negative electrode, the active material comprises any one or a combination of at least two of graphite, silicon-carbon composite or silicon-oxygen composite.
  5. The method of any one of claims 1 to 4, characterized in that the step of dry-mixing the active material, the conductive agent, and the main binder to obtain the first dry material comprises: performing a first mixing at a first dry-mixing rotate speed firstly; and then performing a second mixing at a second dry-mixing rotate speed higher than the first dry-mixing rotate speed; preferably, the dry-mixing is carried out in a high-speed mixer with a cutter and a scraper; preferably, under the first dry-mixing rotate speed, a rotate speed of the cutter is 1000 rpm to 30000 rpm, and a rotate speed of the scraper is 50 rpm to 1000 rpm; preferably, under the second dry-mixing rotate speed, a rotate speed of the cutter is 1500 rpm to 30000 rpm, and a rotate speed of the scraper is 50 rpm to 1000 rpm; preferably, a duration of the first mixing is 1 min to 60 min; preferably, a duration of the second mixing is 1 min to 60 min; and preferably, after the dry-mixing, a sieving is performed to obtain a first dry material of 8 mesh to 50 mesh.
  6. The method of any one of claims 1 to 5, characterized in that the glue liquid is added to the first dry material for dispersion so that a solid content of system is 70wt% to 90wt%, and a ratio of a mass of the main binder in the first dry material to a total mass of the dispersion binder and the aqueous binder in the glue liquid is controlled to be (0.5 to 3):1; preferably, a temperature of the drying treatment is 0°C to 120°C, and a duration of the drying treatment is 2 h to 24 h; preferably, the second dry material has a particle size of 8 mesh to 40 mesh; preferably, on a basis that a mass of the second dry material is 100wt%, a mass of the active material is 92wt% to 96wt%; preferably, on a basis that a mass of the second dry material is 100wt%, a mass of the conductive agent is 0.5wt% to 1.5wt%; preferably, on a basis that a mass of the second dry material is 100wt%, a total mass of binders is 2.5wt% to 8.5wt%; preferably, in the second dry material, a mass ratio of the main binder, the dispersion binder, and the aqueous binder is (1 to 12):(1 to 3):1; preferably, on a basis that a mass of the second dry material is 100wt%, a mass of the main binder is 1wt% to 6wt%; preferably, on a basis that a mass of the second dry material is 100wt%, a mass of the dispersion binder is 1wt% to 1.5wt%; and preferably, on a basis that a mass of the second dry material is 100wt%, a mass of the aqueous binder is 0.5wt% to 1wt%.
  7. The method of any one of claims 1 to 6, characterized in that the step of pulverizing the second dry material is carried out in a pulverizer and/or a high-speed pulverizer; preferably, the step of pulverizing the second dry material is carried out at a rotate speed of 1500 rpm to 30000 rpm; preferably, the powder has a particle size of 35 mesh to 200 mesh; and preferably, a method of pressing comprises rolling.
  8. The method of any one of claims 1 to 7, characterized in that the step of formulating the dispersion binder and the aqueous binder into the glue liquid comprises: formulating the dispersion binder and the aqueous binder into a liquid A and a liquid B, each having a mass concentration of 5wt% to 30wt%, using solvent water; and then mixing the liquid A and the liquid B, controlling a mass ratio of the dispersion binder to the aqueous binder to be (1 to 3):1, and adjusting the mass concentration to be 5wt% to 30wt% using solvent water to obtain the glue liquid; and the dispersion binder is a small molecule polymer binder; wherein the small molecule polymer binder is any one or a combination of at least two of polyvinylpyrrolidone, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, or polyethylene glycol; the step of dry-mixing the active material, the conductive agent, and the main binder to obtain the first dry material comprises: dry-mixing the negative electrode active material, the conductive agent, and the main binder in a high-speed mixer, performing a first mixing at a first dry-mixing rotate speed firstly, performing a second mixing at a second dry-mixing rotate speed higher than the first dry-mixing rotate speed, and performing a sieving to obtain a first dry material of 8 mesh to 50 mesh; the main binder comprises polytetrafluoroethylene and/or polytetrafluoroethylene derivative; the step of adding the glue liquid to the first dry material for dispersion, and performing the drying treatment to obtain the second dry material comprises: adding the glue liquid to the first dry material for dispersion so that a solid content of system is 70wt% to 90wt% and a ratio of a mass of the main binder in the first dry material to a total mass of the dispersion binder and the aqueous binder in the glue liquid is controlled to be (0.5 to 3):1; and performing the drying treatment for 2 h to 24 h at 0°C to 120°C to obtain a second dry material with a particle size of 8 mesh to 40 mesh; on a basis that a mass of the second dry material is 100wt%, a mass of the active material is 92wt% to 96wt%, a mass of the conductive agent is 0.5wt% to 1.5wt%, a mass of the main binder is 1wt% to 6wt%, a mass of the dispersion binder is 1wt% to 1.5wt%, and a mass of the aqueous binder is 0.5wt% to 1wt%; in the second dry material, a mass ratio of the main binder, the dispersion binder and the aqueous binder is (1 to 12):(1 to 3):1; the step of pulverizing the second dry material to form the binder-fibrillized powder comprises: pulverizing the second dry material in a pulverizer and/or a high-speed pulverizer at 1500 rpm to 30000 rpm to form the binder-fibrillized powder, the powder has a particle size of 35 mesh to 200 mesh; the step of pressing the powder to obtain the dry-processed electrode comprises calendering the powder using a roller press to obtain a dry-processed negative electrode.
  9. A dry-processed electrode characterized by being obtained using the method of any one of claims 1 to 8.
  10. The dry-processed electrode of claim 9, characterized in that the dispersion binder comprises a small molecule polymer binder; wherein the small molecule polymer binder is any one or a combination of at least two of polyvinylpyrrolidone, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, or polyethylene glycol; and preferably, the aqueous binder comprises any one or a combination of at least two of a polyacrylic acid or a salt of the polyacrylic acid or a copolymer of the polyacrylic acid, carboxymethyl cellulose or a salt of the carboxymethyl cellulose or a copolymer of the carboxymethyl cellulose, an alginate, an SBR emulsion, or PEG.
  11. The dry-processed electrode of claim 9 or 10, characterized in that a mass ratio of the dispersion binder to the aqueous binder in the glue liquid is (1 to 3):1; preferably, a total mass concentration of binders in the glue liquid is 5wt% to 30wt%; preferably, the step for formulating the dispersion binder and the aqueous binder into the glue liquid comprises: formulating the dispersion binder and the aqueous binder into a liquid A and a liquid B respectively, each having a mass concentration of 5wt% to 30wt%; and mixing the liquid A and the liquid B, and adjusting the mass concentration to 5wt% to 30wt% using a solvent to obtain the glue liquid; and preferably, the solvent comprises water.
  12. The dry-processed electrode of any one of claims 9 to 11, characterized in that the main binder comprises polytetrafluoroethylene and/or polytetrafluoroethylene derivative; preferably, the polytetrafluoroethylene derivative comprises any one or a combination of at least two of a tetrafluoroethylene-hexafluoropropylene copolymer, an ethylene-tetrafluoroethylene copolymer, or a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer; preferably, the conductive agent comprises any one or a combination of at least two of conductive carbon black, carbon nanofibers, carbon nanotubes, or graphene; preferably, when the dry-processed electrode is a negative electrode, the active material comprises any one or a combination of at least two of graphite, silicon-carbon composite or silicon-oxygen composite.
  13. The dry-processed electrode of any one of claims 9 to 12, characterized in that the step of dry-mixing the active material, the conductive agent, and the main binder to obtain the first dry material comprises: performing a first mixing at a first dry-mixing rotate speed firstly; and then performing a second mixing at a second dry-mixing rotate speed higher than the first dry-mixing rotate speed; preferably, the dry-mixing is carried out in a high-speed mixer with a cutter and a scraper; preferably, under the first dry-mixing rotate speed, a rotate speed of the cutter is 1000 rpm to 30000 rpm, and a rotate speed of the scraper is 50 rpm to 1000 rpm; preferably, under the second dry-mixing rotate speed, a rotate speed of the cutter is 1500 rpm to 30000 rpm, and a rotate speed of the scraper is 50 rpm to 1000 rpm; preferably, a duration of the first mixing is 1 min to 60 min; preferably, a duration of the second mixing is 1 min to 60 min; and preferably, after the dry-mixing, a sieving is performed to obtain a first dry material of 8 mesh to 50 mesh.
  14. The dry-processed electrode of any one of claims 9 to 13, characterized in that the glue liquid is added to the first dry material for dispersion so that a solid content of system is 70wt% to 90wt%, and a ratio of a mass of the main binder in the first dry material to a total mass of the dispersion binder and the aqueous binder in the glue liquid is controlled to be (0.5 to 3): 1; preferably, a temperature of the drying treatment is 0°C to 120°C, and a duration of the drying treatment is 2 h to 24 h; preferably, the second dry material has a particle size of 8 mesh to 40 mesh; preferably, on a basis that a mass of the second dry material is 100wt%, a mass of the active material is 92wt% to 96wt%; preferably, on a basis that a mass of the second dry material is 100wt%, a mass of the conductive agent is 0.5wt% to 1.5wt%; preferably, on a basis that a mass of the second dry material is 100wt%, a total mass of binders is 2.5wt% to 8.5wt%; preferably, in the second dry material, a mass ratio of the main binder, the dispersion binder, and the aqueous binder is (1 to 12) :(1 to 3):1; preferably, on a basis that a mass of the second dry material is 100wt%, a mass of the main binder is 1wt% to 6wt%; preferably, on a basis that a mass of the second dry material is 100wt%, a mass of the dispersion binder is 1wt% to 1.5wt%; and preferably, on a basis that a mass of the second dry material is 100wt%, a mass of the aqueous binder is 0.5wt% to 1wt%.
  15. A battery characterized by comprising the dry-processed electrode of claims 9 to 14.

Description

BACKGROUND OF DISCLOSURE 1. Field of the Disclosure The present disclosure relates to a technical field of batteries, and in particular to a method for manufacturing a dry-processed electrode and a resulting dry-processed electrode and use thereof. 2. Description of the Related Art Thanks to economic globalization and ever-increasing requirements for carbon neutrality and environmental protection of various countries around the world, replacing traditional energy sources with new energy sources has become a strong development trend. Lithium ion batteries are increasingly indispensable in fields of power and energy storage, and have become the main force in a field of new energy sources. With rapid development of lithium-ion battery technology and significant increase in market proportion, development of lithium-ion power batteries is increasingly moving towards low-cost, high-energy density, and fast charging technology. In terms of battery manufacturing, more attention is paid to resource costs, energy consumption, and recovery of volatile solvents. In terms of improving the energy density performance of the product, more attention is paid to thick electrode manufacturing and initial efficiency performance, and in terms of improving the rapid charging and power of the product, more attention is paid to rate characteristic of the battery. For a manufacturing process of lithium battery cells, key performances of the cells are mainly determined by a manufacturing process of an electrode sheet. In the related art, the manufacturing methods of the electrode sheet are mainly classified as wet process (or slurry-based/solution process) and dry process (or solvent-free process), and the wet process is the mainstream. In the wet process, a binder, a solvent, and a conductive agent are generally prepared into a conductive slurry, and then the active substance is added in portions to stir, and finally the solvent is added to adjust the viscosity of the slurry. However, in a conventional wet process, dispersion of the conductive agent is poor. At the same solid content, the viscosity of the slurry is higher than that of the dry process, and internal resistance of the manufactured battery electrode sheet is also larger. The dry-processed electrode technology is a new manufacturing process different from the wet method, basically does not use or uses a small amount of harmless solvent, and can increase compaction and manufacture a thick electrode, the dry-processed battery may increase energy density by more than 20%, and has more excellent kinetic characteristics, and in the thick electrode, cycle performance, impedance, and the like are preferable, so that the battery manufacturing cost and energy consumption may be greatly reduced, and battery performance may be greatly improved. In the related art, a more feasible dry manufacturing process uses a fibrillizable PTFE binder, for example, PTFE, SP, and graphite are mixed and stirred, to obtain a premix; premix fibrillization, in which the premix is subjected to fibrillization treatment to obtain a fibrillized mixture; baking the mixture, and baking the fibrillized mixture to obtain a cotton candy-like mixture; the mixture is formed into a film, and the cotton candy-like mixture is repeatedly folded and subjected to multiple rolling treatments to obtain a thicker film sheet; a film sheet thinning process for thinning the thicker film sheet to obtain a negative electrode film sheet conforming to requirements for the thickness; the dry film-forming preparation process of the negative electrode and the negative electrode dry film have advantages of simple process, less waste of materials, and low labor and material cost, and may improve production efficiency and production performance. For another example, a dry-processed electrode film is prepared by uniformly mixing an active material, a conductive agent, and a PTFE polymer film to obtain a mixture, performing fibrillization treatment to obtain a mixture, and then performing heating and rolling (or calendering) treatment. This method can greatly reduce the process difficulty of dry preparation of the electrode sheet by using a polymer film, and has low requirements for equipment used for the fibrillization, the fibrillization is more complete, and dispersion uniformity among components is better. However, there is a problem that the PTFE binder is not tolerant in the negative electrode, and the C-F bond may react with lithium during charging, thereby consuming part of the lithium ions and reducing the initial efficiency of the battery, which resulting in capacity loss. Research in the related art mainly carries out PTFE modification or uses other binders to improve this problem. However, PTFE modification is mainly based on addition of fluorine-containing monomers to copolymerize with tetrafluoroethylene, and the side reaction of C-F bond with lithium is still present. Among other binders, the most commonly used are poly