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CN-122025640-A - Low-internal-resistance lithium ion battery pole piece structure and manufacturing method thereof

CN122025640ACN 122025640 ACN122025640 ACN 122025640ACN-122025640-A

Abstract

The invention discloses a pole piece structure of a lithium ion battery with low internal resistance and a manufacturing method thereof, wherein the pole piece structure comprises a current collector, a first coating and a second coating which are arranged in a laminated way, the first coating is positioned between the current collector and the second coating, a three-dimensional conductive network is formed by containing linear and punctiform composite conductive agents, and the content of the conductive agents of the second coating is lower; the type of conductive material, the thickness of the coating, the conductive agent duty cycle, and the type of current collector are defined. The manufacturing method comprises the steps of slurry preparation, layered coating, sectional drying, rolling compaction and the like, and the dispersion, drying and rolling parameters are accurately controlled. The invention can obviously reduce the internal resistance of the pole piece, balance the conductivity and the energy density, improve the structural stability of the pole piece and the cycle life of the battery, control the production cost, adapt to the existing production line, have stronger industrialization value, and can meet the application requirements of high-performance lithium ion batteries.

Inventors

  • HAN YONGBIN

Assignees

  • 东莞力朗电池科技有限公司

Dates

Publication Date
20260512
Application Date
20260320

Claims (10)

  1. 1. The low internal resistance lithium ion battery pole piece structure comprises a current collector and an active material layer arranged on at least one surface of the current collector, and is characterized in that the active material layer comprises a first coating and a second coating which are arranged in a laminated manner; The first coating is positioned between the current collector and the second coating, the first coating comprises first active substance particles and a first conductive agent, the first conductive agent comprises linear conductive materials and point-shaped conductive materials, the linear conductive materials are mutually overlapped to form a three-dimensional conductive network framework, and the point-shaped conductive materials are distributed among and on the surfaces of the first active substance particles and connect the first active substance particles with the three-dimensional conductive network framework; the second coating layer contains second active material particles and a second conductive agent, and the content of the second conductive agent in the second coating layer is lower than the total content of the first conductive agent in the first coating layer.
  2. 2. The lithium ion battery pole piece structure with low internal resistance according to claim 1, wherein the linear conductive material is one or more of carbon nanotubes, carbon nanofibers or vapor grown carbon fibers; the punctiform conductive material is one or more of conductive carbon black, acetylene black or ketjen black.
  3. 3. The lithium ion battery pole piece structure of claim 1, wherein the thickness of the first coating layer is 1/5 to 1/3 of the total thickness of the active material layer.
  4. 4. The lithium ion battery pole piece structure of claim 1, wherein in the first coating layer, the mass of the linear conductive material accounts for 0.5 to 3 percent of the total solid content of the first coating layer, and the mass of the punctiform conductive material accounts for 0.5 to 2 percent of the total solid content of the first coating layer.
  5. 5. The lithium ion battery pole piece structure with low internal resistance according to claim 1, wherein the second coating layer does not contain linear conductive materials, the second conductive agent is only punctiform conductive materials, and the mass of the second conductive agent accounts for 0.5-1.5% of the total solid content of the second coating layer.
  6. 6. The lithium ion battery pole piece structure with low internal resistance according to claim 1, wherein the current collector is carbon-coated aluminum foil or photo-aluminum foil, and the conductive coating of the carbon-coated aluminum foil is in contact with the first coating.
  7. 7. The manufacturing method of the low-internal-resistance lithium ion battery pole piece structure is characterized by comprising the following steps: Step S1, preparing a first slurry, mixing a first active substance, a first conductive agent containing linear conductive materials and punctiform conductive materials, a first binder and a first solvent, and dispersing the linear conductive materials through a first dispersing process and mutually overlapping to form a pre-three-dimensional network; step S2, preparing a second slurry, mixing a second active material, a second conductive agent, a second binder and a second solvent, and uniformly dispersing the components through a second dispersing process; step S3, coating the first slurry prepared in the step S1 on the surface of a current collector, and forming a first coated blank after first drying treatment; And S4, coating the second slurry prepared in the step S2 on the surface of the first coating blank, and performing second drying treatment to enable the first coating blank and the second coating to be cured and molded synchronously, so as to form an active substance layer.
  8. 8. The method of manufacturing a low internal resistance lithium ion battery pole piece structure according to claim 7, wherein the first dispersion process in the step S1 is a combination of high-speed shearing dispersion and ultrasonic-assisted dispersion, the dispersion temperature is controlled to be 25-45 ℃, and the viscosity of the slurry after dispersion is 3000-8000 mPas.
  9. 9. The method of manufacturing a low internal resistance lithium ion battery pole piece structure according to claim 7, wherein the first drying process and the second drying process in the step S4 are performed in a sectional drying manner, and the sectional drying manner comprises a low temperature section and a high temperature section, wherein the temperature of the low temperature section is 50 ℃ to 70 ℃, and the temperature of the high temperature section is 80 ℃ to 120 ℃.
  10. 10. The method of manufacturing a low internal resistance lithium ion battery electrode sheet structure according to claim 7, further comprising a step S5 of roll compacting the dried electrode sheet at a temperature of 60 to 90 ℃ to control the porosity of the first coating layer to 25 to 35% and the porosity of the second coating layer to 30 to 40% after the step S4.

Description

Low-internal-resistance lithium ion battery pole piece structure and manufacturing method thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a low-internal-resistance lithium ion battery pole piece structure and a manufacturing method thereof. Background The lithium ion battery is widely applied to the fields of various electronic equipment, energy storage and power batteries due to the advantages of high energy density, long cycle life and the like, and the pole piece is used as a core component for battery energy storage and charge conduction, and the structural design of the pole piece directly determines key performances such as battery internal resistance, energy density and the like. The existing lithium ion battery pole piece mostly adopts a single active substance coating structure, and the conductive agent is mostly single punctiform conductive material, so that the problems of discontinuous conductive network, conductive dead angle and the like are easy to occur, the internal resistance of the pole piece is higher, and the charge and discharge efficiency and high-rate performance of the battery are affected. When the consumption of the conductive agent is increased to reduce the internal resistance, the active material occupies a filling space to reduce the energy density, the single coating is difficult to meet the requirements of conductivity and energy storage, and meanwhile, the contact resistance between the current collector and the coating is larger, so that the improvement of the performance of the pole piece is further restricted. Disclosure of Invention In order to overcome the defects of the prior art, the invention provides a low-internal-resistance lithium ion battery pole piece structure and a manufacturing method thereof, which can effectively solve the problems of the prior art. The technical scheme adopted for solving the technical problems is as follows: the low internal resistance lithium ion battery pole piece structure comprises a current collector and an active material layer arranged on at least one surface of the current collector, wherein the active material layer comprises a first coating and a second coating which are arranged in a laminated manner; The first coating is positioned between the current collector and the second coating, the first coating comprises first active substance particles and a first conductive agent, the first conductive agent comprises linear conductive materials and point-shaped conductive materials, the linear conductive materials are mutually overlapped to form a three-dimensional conductive network framework, and the point-shaped conductive materials are distributed among and on the surfaces of the first active substance particles and connect the first active substance particles with the three-dimensional conductive network framework; the second coating layer contains second active material particles and a second conductive agent, and the content of the second conductive agent in the second coating layer is lower than the total content of the first conductive agent in the first coating layer. As a further description of the above technical solution, the linear conductive material is one or more of carbon nanotubes, carbon nanofibers, or vapor grown carbon fibers; the punctiform conductive material is one or more of conductive carbon black, acetylene black or ketjen black. As a further description of the above technical solutions, the thickness of the first coating layer is 1/5 to 1/3 of the total thickness of the active material layer. As a further description of the above technical solution, in the first coating layer, the mass of the linear conductive material is 0.5% to 3% of the total solid content of the first coating layer, and the mass of the dot-shaped conductive material is 0.5% to 2% of the total solid content of the first coating layer. As a further description of the above technical solution, the second coating layer does not contain a linear conductive material, and the second conductive agent is only a dot-shaped conductive material, and its mass is 0.5% to 1.5% of the total solid content of the second coating layer. As a further description of the above technical solution, the current collector is a carbon coated aluminum foil or a photo-aluminum foil, and the conductive coating of the carbon coated aluminum foil is in contact with the first coating. The manufacturing method of the low-internal-resistance lithium ion battery pole piece structure comprises the following steps: Step S1, preparing a first slurry, mixing a first active substance, a first conductive agent containing linear conductive materials and punctiform conductive materials, a first binder and a first solvent, and dispersing the linear conductive materials through a first dispersing process and mutually overlapping to form a pre-three-dimensional network; step S2, preparing a second slurry, mixing a se