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CN-122025660-A - Porous current collector, pole piece, battery and preparation method

CN122025660ACN 122025660 ACN122025660 ACN 122025660ACN-122025660-A

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a porous current collector, a pole piece, a battery and a preparation method. The porous current collector comprises a matrix functional layer and an antioxidation layer covering the surface of the matrix functional layer; the porous current collector is provided with micropores penetrating through the substrate functional layer and the antioxidation layer; the micropore is of a non-cylindrical structure, and the invention also provides a preparation method of the porous current collector, a pole piece and a battery. The invention solves the problems that the existing porous current collector is difficult to realize effective balance between ion transmission efficiency and mechanical strength, and also solves the problems that the existing porous current collector has low control precision of pore wall morphology, is easy to cause stress concentration and has poor interface binding force of an active coating.

Inventors

  • JIA JUNHUI

Assignees

  • 山西师范大学

Dates

Publication Date
20260512
Application Date
20260309

Claims (10)

  1. 1. The porous current collector is characterized by comprising a matrix functional layer and an antioxidation layer covering the surface of the matrix functional layer; The porous current collector is provided with micropores penetrating through the substrate functional layer and the antioxidation layer; the microwells are of non-cylindrical configuration.
  2. 2. The porous current collector according to claim 1, wherein the inner wall of the micropore is provided with an inclined plane, and an included angle formed by the inclined plane and a horizontal plane is 5-85 degrees; and/or the section of the micropore along the radial direction is circular, elliptic or hexagonal; and/or the inner wall surface of the micropore is an inclined surface, a folded surface or a wavy surface; and/or the section of the micropore along the axial direction is at least one of inverted trapezoid, gourd-like shape and corrugated cylinder shape; And/or micropores on the porous current collector are arranged in parallel, staggered and uniform, circular, rectangular, elliptic or polygonal; And/or the equivalent diameter of the micropores is 10-1000 μm; and/or the opening ratio of the porous current collector is 10-70%.
  3. 3. The porous current collector according to claim 1, wherein the material of the base functional layer is at least one selected from the group consisting of chromium, nickel, copper, aluminum, silver and zinc; and/or the material of the oxidation resistance layer is at least one selected from zinc layer, nickel layer, aluminum layer and chromium; and/or the substrate functional layer is of a single-layer metal structure or a metal cladding structure; and/or the thickness of the porous current collector is 4-30 μm.
  4. 4. A method of preparing a porous current collector according to any one of claims 1 to 3, comprising the steps of: S1, arranging an auxiliary layer on at least one surface of a substrate supporting layer; s2, processing a basal body functional layer with micropores with a non-cylindrical structure on the surface of the auxiliary layer; S3, stripping the substrate functional layer, and performing antioxidation treatment on the surface of the substrate functional layer to obtain the porous current collector.
  5. 5. The method for preparing a porous current collector according to claim 4, wherein in S1, an auxiliary layer is coated on both sides of the base support layer; the step S2 comprises the step of processing a substrate functional layer with micropores with a non-cylindrical structure on the surface of the auxiliary layer by adopting wet etching, laser processing, precision electroforming or mask electrodeposition.
  6. 6. The method for preparing a porous current collector according to claim 5, wherein in the step S1, the coating process parameters of the auxiliary coating layer are that the coating speed is 3-20 m/min, the baking temperature is 60-80 ℃ and the baking time is 30-60S; The S2 comprises the steps of coating positive photoresist on the surface of an auxiliary layer, exposing and developing to obtain a convex structure, growing a substrate functional layer on a part without photoresist through an electroplating thickening process, soaking in acetone solution, and removing redundant photoresist through ultrasonic assistance to form micropores with a non-cylindrical structure on the substrate functional layer.
  7. 7. The method for preparing the porous current collector according to claim 6, wherein in the step S2, the process parameters of coating the positive photoresist on the surface of the auxiliary layer are that the coating speed is 10-25 m/min, the baking temperature is 80-110 ℃, and the baking time is 2-5 min; And/or the technological parameters of exposure and development are that ultraviolet light with the wavelength of 365nm is adopted for exposure, the exposure energy is 100-150 mJ/cm 2 , a developing solution is sodium hydroxide (NaOH) solution, and the development time is 1-3 min; and/or the process parameters of the electroplating thickening process are that the temperature is 20-30 ℃, the cathode current density is 1-6A/dm 2 , the electroplating time is 15-25 min, and the electroplating thickening is at least 7 mu m; And/or the electroplating thickening process adopts electroplating liquid comprising copper sulfate, sulfuric acid, chlorine-containing compounds and brightening agents; And/or the stripping process parameters are that the stripping speed is 3-8 m/min, the unreeling tension is 80-120N, and the reeling tension is 50-100N; And/or the antioxidant treatment has the technological parameters that the components of the passivation solution comprise at least one of silane coupling agent, titanate, benzotriazole, nickel sulfamate, benzotriazole and chromic anhydride, the soaking time is 2-5 min, and the soaking temperature is 45-65 ℃.
  8. 8. The method for preparing a high-performance composite current collector according to claim 4, wherein the substrate supporting layer is made of metal or composite metal, and the thickness of the substrate supporting layer is 5-50 μm; And/or the material components of the auxiliary layer are selected from conductive release agents, wherein the conductive release agent components comprise film forming base materials, conductive fillers, release functional agents, auxiliary agents and solvents, the film forming base materials are selected from one or two of perfluoropolyether acrylate and polysiloxane modified acrylate, the conductive fillers are selected from nano silver wires and graphene quantum dots, the release functional agents are selected from perfluorooctyl triethoxysilane and polytetrafluoroethylene micro powder, the auxiliary agents are selected from polycarboxylate dispersants, organosilicon leveling agents and polyether modified siloxane defoamers, and the solvents are selected from water and isopropanol; and/or the thickness of the auxiliary layer is 20-50 mu m.
  9. 9. A pole piece, characterized in that the current collector of the pole piece is selected from the porous current collector according to any one of claims 1 to 3 or from the porous current collector produced by the production method according to any one of claims 4 to 8.
  10. 10. A battery characterized in that the pole piece of the battery is the pole piece of claim 9.

Description

Porous current collector, pole piece, battery and preparation method Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a porous current collector, a pole piece, a battery and a preparation method. Background With the rapid development of portable electronic devices, electric vehicles and large-scale energy storage industries, the market demand for high-energy-density energy storage devices is increasing. The lithium battery has become the first power supply technology in the fields of electronic equipment, electric automobiles and energy storage systems by virtue of the comprehensive advantages of high energy density, long cycle life, environmental friendliness and the like. The current collector is used as one of key components of the lithium ion battery, and the performance of the current collector has a decisive influence on the internal resistance, the energy density, the multiplying power performance and the structural reliability of the battery. In recent years, porous current collectors have become an important development direction of current collector technology due to their unique three-dimensional topology. However, the porous current collector in the prior art still has the following defects that 1) the microstructure parameters are not optimized cooperatively, the aperture size, the geometric morphology and the arrangement mode are not optimized systematically, the effective balance between the ion transmission efficiency and the mechanical strength is difficult to realize, 2) the hole wall morphology is low in control precision, the hole wall is mostly in a vertical structure or an undefined inclination angle, stress concentration is easy to cause, the interface binding force of an active coating is poor, technical barriers are generated in the forming process (such as a demolding process), 3) the tab area suitability design is lost, the high current density characteristic of a tab connection area is not optimized structurally, the contact resistance of the area is higher, the high current charge and discharge performance of a battery is influenced, 4) the aperture ratio and the thickness matching are unbalanced, the cooperative design of the aperture ratio and the thickness parameter of the current collector is unreasonable, and the multiple requirements of light weight, high load and structural stability are difficult to meet simultaneously. In addition, in the aspect of the preparation process, the problems of complex process flow, high manufacturing cost and the like of a braiding method, a mechanical punching method, a template method and the like exist at present, and the technology is limited by the technology, so that the dual technical indexes of ultrathin design (the thickness is less than or equal to 20 mu m) and high tensile strength (more than or equal to 200 MPa) are difficult to be considered. In view of the foregoing, the prior art still has significant shortcomings in terms of structural optimization and controllable preparation of the porous current collector, and development of a novel porous current collector with excellent electrochemical performance, mechanical performance and manufacturability and a preparation method thereof are needed. Disclosure of Invention In view of the above, one of the purposes of the present invention is to provide a porous current collector to solve the problem that the existing porous current collector is difficult to achieve effective balance between ion transmission efficiency and mechanical strength, and another purpose of the present invention is to provide a preparation method of a porous current collector, a pole piece and a battery to solve the problem that the existing porous current collector is difficult to achieve the dual technical indexes of ultra-thin design (thickness less than or equal to 20 μm) and high tensile strength (more than or equal to 200 MPa). In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: A porous current collector comprises a matrix functional layer and an antioxidation layer covered on the surface of the matrix functional layer; The porous current collector is provided with micropores penetrating through the substrate functional layer and the antioxidation layer; the microwells are of non-cylindrical configuration. By arranging the micropores into a non-cylindrical structure, the dilemma of 'compromise' of stress concentration and uniform mass transfer of the traditional straight holes is effectively broken. The method specifically comprises the steps that multistage stress dispersion nodes are formed on the wall of the variable cross section hole when the variable cross section hole is stretched/compressed, crack propagation paths are continuously deflected, macroscopic mechanical strength is improved, meanwhile, the cross section of the hole channel is periodically contracted-expanded along the thickness dir