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CN-122000293-A - Flexible electrode film and preparation method and processing equipment thereof

CN122000293ACN 122000293 ACN122000293 ACN 122000293ACN-122000293-A

Abstract

The invention discloses a flexible electrode film, a preparation method and processing equipment thereof, and belongs to the technical field of electrochemistry and environmental engineering. The thickness of the flexible electrode film is 40-1000 mu m, the flexible electrode film is provided with a fiber three-dimensional network, active materials are adhered in the fiber three-dimensional network, pore structures which are mutually interweaved with the fiber three-dimensional network are further arranged in the flexible electrode film, the pore structures are composed of a plurality of holes, and the holes are in a through or semi-through pore shape. The invention introduces soluble salt as a temporary structure regulating component, and forms a uniformly distributed pore structure in the electrode after subsequent removal, thereby improving ion transmission conditions in the thick electrode and improving the utilization rate of active substances. The fibrous three-dimensional network structure and the pore structure formed by salt pore-forming cooperate with each other, so that the electrode has higher effective capacity and energy density in unit area.

Inventors

  • SUN XIANZHONG
  • MA YANWEI
  • SUN YU
  • WANG DONGLIANG

Assignees

  • 齐鲁中科电工先进电磁驱动技术研究院
  • 中国科学院电工研究所

Dates

Publication Date
20260508
Application Date
20260205

Claims (10)

  1. 1. The flexible electrode film is characterized by having a thickness of 40-1000 mu m, a fibrous three-dimensional network is arranged on the flexible electrode film, active materials are adhered in the fibrous three-dimensional network, pore structures which are mutually interweaved with the fibrous three-dimensional network are further arranged in the flexible electrode film, the pore structures are composed of a plurality of holes, and the holes are in a through or semi-through pore morphology.
  2. 2. The flexible electrode film of claim 1, wherein the pores of the fibrillated three-dimensional network have a diameter of no more than 1mm, and the dimensions of the pores are less than the overall thickness of the flexible electrode film.
  3. 3. The method for producing a flexible electrode film according to claim 1 or 2, characterized in that the method comprises the steps of: S1, adding soluble salt accounting for 0.01-10% of the mass of raw materials into the raw materials to obtain a raw material mixture, wherein the raw materials comprise an active material, a conductive additive and a fiberizable binder, and the mass part ratio of the active material to the conductive additive to the fiberizable binder is 60-96:2-20:2-20; s2, premixing the raw material mixture; S3, carrying out fibrosis treatment on the mixture obtained in the step S2 to obtain a fibrosis powder; s4, performing film forming treatment on the fiberized powder to obtain a formed electrode film; S5, carrying out water washing treatment on the formed electrode film to obtain a water-washed electrode film; And S6, drying and rolling the water-washed electrode film to obtain the flexible electrode film.
  4. 4. The method for producing a flexible electrode film according to claim 3, wherein the soluble salt is one or more of sodium chloride, potassium chloride, magnesium chloride, sodium sulfate, potassium sulfate, magnesium nitrate, magnesium sulfate, sodium nitrate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, and ammonium bicarbonate; The soluble salt has a particle size of not more than 1mm.
  5. 5. The method for preparing a flexible electrode film according to claim 3, wherein the active material is one or more of a carbon-based active material and a lithium ion intercalation material, the fiberizable binder is polytetrafluoroethylene or a mixture of polytetrafluoroethylene and carboxymethyl cellulose salt, and the conductive additive is one or more of conductive carbon black, carbon aerogel, carbon nanotubes and graphene.
  6. 6. A method of producing a flexible electrode film according to claim 3, wherein the amount of moisture in the gas used for the fiberizing treatment is not more than 1% by volume; the pressure of the cavity is not lower than 0.4MPa in the fiberizing process.
  7. 7. The method according to any one of claims 3 to 6, wherein the water washing treatment is a water washing treatment of the molded electrode film for 1 to 10 minutes to dissolve soluble salts in the molded electrode film in water, the water washing treatment being a static immersion washing, a slow flow washing or a combination thereof; The drying treatment is low-disturbance drying, including vacuum drying or hot air drying or infrared heating drying.
  8. 8. The processing equipment of the flexible electrode film is characterized by comprising a material premixing device, a fiberizing device, a rolling device, a water washing device, a drying device and a winding device which are sequentially communicated; The material premixing device is used for mixing raw materials to obtain a raw material mixture; the fiberizing device is used for enabling the raw material mixture to complete the fiberizing process to obtain fiberized powder; the rolling device is used for enabling the fiberized powder to finish film forming treatment to obtain a formed electrode film; the washing device is used for washing out soluble salt serving as a temporary structural phase in the formed electrode film so as to form a through pore structure on the premise of keeping the integrity of a fibrous three-dimensional network structure of the formed electrode film; the drying device is used for drying the washed formed electrode film; the winding device is used for winding the dried formed electrode film; The fiberizing apparatus is also in communication with an air supply that causes the pressure inside the fiberizing apparatus to be not lower than 0.4MPa.
  9. 9. The flexible electrode film processing apparatus according to claim 8, further comprising a water removal device between the fiberizing apparatus and the gas supply device, the water removal device causing a volume percentage of moisture in the gas entering the fiberizing apparatus to be not more than 1%.
  10. 10. The flexible electrode film processing apparatus according to claim 9, wherein the water removal device is a multi-stage water removal device, and the water removal device is specifically one or a combination of a plurality of devices selected from a freeze dryer, an adsorption dryer, and a freeze-adsorption combined dryer.

Description

Flexible electrode film and preparation method and processing equipment thereof Technical Field The invention relates to the technical field of electrochemistry and environmental engineering, in particular to a flexible electrode film, a preparation method and processing equipment thereof. Background With the rapid development of energy storage technology, the lithium ion battery is used as an environment-friendly energy storage and release device, and is widely applied to various fields of daily life, traffic, aerospace and the like and becomes a mainstream energy storage device in the current society by virtue of high energy density (more than or equal to 200 Wh/kg), good cycle stability (more than 1000 cycles) and mature production and preparation process. In the rapid development process of new energy industry, the requirement of society on the ongoing electrified revolution is higher and higher, N-methyl pyrrolidone (NMP) required in the traditional wet electrode preparation process has high toxicity and volatility, high cost and serious pollution, and when thick electrodes are manufactured by the wet process, the evaporation of solvent in the drying process of high-quality load slurry can disturb the distribution of adhesive on the electrodes to cause cracks inside the electrodes, and limit the industrialization steps of lithium ion batteries. Compared with the traditional wet electrode, the dry electrode preparation process has no solvent introduction, avoids high pollution and high energy consumption procedures in the wet process, has the advantages of small equipment occupation, low investment, low cost and the like, and can reduce the comprehensive cost by more than 18 percent compared with the wet process, thereby being a necessary path for the industrialization upgrade of the lithium ion battery. The traditional coating process is to mix active materials, conductive agents and binders to prepare slurry, coat the slurry on a current collector by a coating device, and dry the slurry to prepare an electrode, however, the traditional wet electrode technology is limited by critical cracking thickness due to volume shrinkage and stress in the drying process. It is difficult to prepare an electrode exceeding 200 μm according to the critical cracking thickness (CCT, CRITICAL CRACKING THICKNESS) calculation formula: , Wherein h max is the critical cracking thickness, G is the shear modulus of the particle, M is the number of covalent bonds, Is the particle volume fraction at random close packing, R is the particle radius,Is the air-solvent interfacial tension. For example, the thickness of the wet-process lithium nickel cobalt manganese oxide ternary electrode is not more than 175 mu m, the thickness of the wet-process silicon carbon negative electrode is not more than 100 mu m, and the thickness of the wet-process active carbon electrode is not more than 160-200 mu m. Thus requiring dry electrode processes such as the fabrication of thick electrodes. The existing dry electrode preparation process comprises the working procedures of electrode powder mixing, fibrosis, self-supporting film making, hot-pressing compounding and the like, and electrode active materials and conductive agents are bonded together mainly through fibrillation of adhesive polytetrafluoroethylene to form an anode-cathode self-supporting film, the working procedure of the preparation process is complex, and the uniformity of powder mixing and the degree of fibrosis are uncontrollable. Compared with the existing wet coating process, the dry film-making process has lower efficiency, the self-supporting film is difficult to calender to the designed thickness due to the reasons of thickness, hardness, density and the like, and the defects of fracture, cracking, surface particle breakage and the like are caused by overlarge internal stress of the electrode film in the calendering process, so that the cost is increased. In addition, thick film ion diffusion paths are long, and the binder of the dry electrode is hydrophobic, and the wetting time is long, resulting in a problem that electrochemical polarization of the electrode in an electrolyte is large. Disclosure of Invention In order to solve the technical problems, the invention provides a flexible electrode film and a preparation method thereof. The flexible electrode film has a fibrous three-dimensional network and a pore structure which is mutually interweaved with the fibrous network. The pore structure can accelerate the transmission of ions, liquid phase and gas phase, thereby solving the problem of large electrochemical polarization in the thick electrode film. The invention further aims to solve the technical problem of providing processing equipment for the flexible electrode film. In order to achieve the above purpose, the invention adopts the following technical scheme: The thickness of the flexible electrode film is 40-1000 mu m, the flexible electrode film is provided with