Composite current collector preparation equipment for negative electrode of lithium ion secondary battery

Abstract

The utility model belongs to the field of batteries, particularly relates to equipment for preparing a composite current collector for a negative electrode of a lithium ion secondary battery, and provides the following scheme aiming at the problem that the safety of the battery in the aspects of needling and the like is poor due to the fact that the heat resistance and the mechanical strength of the conventional equipment are poor. The melt spinning device is mounted at the top end in the fiber weaving chamber; the electrostatic adsorption device is mounted at the middle end in the fiber weaving chamber; the number of the transfer shafts is four, and the transfer shafts are rotationally connected to the side face of the fiber weaving chamber; the fiber aggregate collecting curtain is in transmission connection with the surfaces of the four transfer shafts, and the composite current collector is used as a negative electrode current collector of the lithium ion secondary battery, so that the energy density of the battery is improved; the internal resistance of the battery is reduced, and the rate capability and cycle life of the battery are improved; and the safety performance of the battery is improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a composite current collector preparation device for the negative electrode of a lithium-ion secondary battery. Background Art

[0002] Current collectors play a crucial role in lithium batteries. They connect powdered active materials through coating, collecting and outputting the current generated by the active materials on one hand, and inputting electrode current to the active materials on the other. Typically, copper foil is used as the negative electrode of lithium battery current collectors.

[0003] Composite current collectors, as one of the important technological paths for the future of batteries, have undergone a structural change compared to traditional current collectors. They employ a "sandwich" structure, with a polymer substrate in the middle layer, covered by a metal layer. This structure offers significant advantages, enabling conductivity through an extremely thin metal layer, thereby drastically reducing the amount of metal used.

[0004] Moreover, the composite current collector exhibits excellent safety performance. Due to its thinner metal layer, the burrs generated by the copper foil are smaller, and the polymer material layer, acting as an insulating material, creates a circuit-breaking effect, reducing the possibility of puncturing the separator and effectively preventing battery spontaneous combustion and thermal runaway.

[0005] However, existing composite current collectors also have some shortcomings. For example, their second metal layer is pure copper, and the surface of pure copper foil is easily oxidized to form copper oxide. Copper oxide has a high surface resistance and poor conductivity, which will lead to a decrease in the electrochemical performance of the battery. In addition, most of the composite current collectors in the existing technology use PET (polyethylene terephthalate), PP (polypropylene), PE (polyethylene) or PI (polyimide) as intermediate substrates, which are lacking in heat resistance and mechanical strength. This will lead to a decrease in battery safety in terms of needle penetration and other aspects. Utility Model Content

[0006] The purpose of this invention is to address the shortcomings of existing technologies in terms of heat resistance and mechanical strength, which leads to a decrease in battery safety in areas such as puncture resistance. This invention proposes a composite current collector preparation device for the negative electrode of a lithium-ion secondary battery.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A composite current collector preparation device for lithium-ion secondary battery negative electrode, comprising:

[0009] Fiber weaving room;

[0010] The melt spinning device is installed at the top of the fiber weaving chamber;

[0011] An electrostatic adsorption device is installed in the middle of the fiber weaving chamber.

[0012] There are four transfer shafts, which are rotatably connected to the side of the fiber weaving chamber.

[0013] The fiber aggregate collection curtain is driven and connected to the surfaces of four transfer shafts;

[0014] Fiber aggregates are produced at the outlet of the melt spinning device;

[0015] The carbon layer coating area is located around the fiber aggregate;

[0016] The microgravure coating machine is installed at the top of the carbon layer coating area. Located on top of the fiber aggregate, poly(p-phenylene terephthalamide) (Kevlar) is electrospun into aramid fiber aggregates with a porosity controlled at 10-90%. A conductive carbon-based slurry is coated on both sides of the poly(p-phenylene terephthalamide) Kevlar fiber aggregate. After drying, the slurry is pressurized to form a composite current collector. This composite current collector serves as the negative electrode current collector for lithium-ion secondary batteries, improving battery energy density, reducing internal resistance, enhancing rate performance and cycle life, and improving battery safety.

[0017] As a preferred embodiment of this utility model, a drying device is provided on the right side of the carbon layer coating area. The fiber aggregate penetrates the interior of the drying device and is dried using the drying device. The drying temperature is 60-100℃, the drying time is 0.5-2min, and the thickness of the single functional layer after drying is controlled at 0.2-5μm.

[0018] As a preferred embodiment of this utility model, a roller pressing device is provided on the right side of the drying equipment, and the fiber aggregate passes through the interior of the roller pressing device, which rolls the fiber aggregate.

[0019] As a preferred embodiment of this utility model, a take-up shaft is provided on the right side of the roller pressing equipment. The surface of the take-up shaft is wound around the right end of the fiber aggregate, and the take-up shaft is used to drive the take-up of the fiber aggregate.

[0020] As a preferred embodiment of this utility model, a collection trough is installed at the bottom of the middle part of the carbon layer coating area. The collection trough is located at the bottom of the fiber aggregate and the microgravure coating machine, and is used to collect the liquid that falls out of the microgravure coating machine.

[0021] In a preferred embodiment of this utility model, the top of the fiber aggregate collecting curtain is attached to the left end of the fiber aggregate surface, and the fiber aggregate collecting curtain is used to assist in the production of fiber aggregates. Beneficial effects

[0022] Poly(p-phenylene terephthalamide) (Kevlar) is electrospun into aramid fiber aggregates with a porosity controlled at 10-90%. A conductive carbon-based slurry is coated on both sides of the poly(p-phenylene terephthalamide) (Kevlar) fiber aggregates. After the slurry dries, it is pressurized to form a composite current collector. The composite current collector is used as the negative electrode current collector in lithium-ion secondary batteries, which improves the battery's energy density, reduces the battery's internal resistance, improves the battery's rate performance and cycle life, and enhances the battery's safety performance. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the production process of this utility model.

[0024] In the diagram: 1. Melt spinning device; 2. Transfer shaft; 3. Electrostatic adsorption device; 4. Fiber aggregate collection curtain; 5. Fiber aggregate; 6. Collection tank; 7. Microgravure coating machine; 8. Carbon coating area; 9. Drying equipment; 10. Roller pressing equipment; 11. Rewinding shaft. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Example

[0026] Reference Figure 1 A composite current collector preparation device for lithium-ion secondary battery negative electrode, comprising:

[0027] Fiber weaving room;

[0028] Melt spinning device 1, which is installed at the top of the fiber weaving chamber;

[0029] Electrostatic adsorption device 3 is installed in the middle of the fiber weaving chamber.

[0030] Transfer shaft 2, four of them are provided, and the transfer shaft 2 is rotatably connected to the side of the fiber weaving chamber;

[0031] Fiber aggregate collection curtain 4 is driven to the surface of four transfer shafts 2;

[0032] Fiber aggregate 5 is produced at the outlet of melt spinning device 1;

[0033] Carbon layer coated area 8 is disposed around the fiber aggregate 5;

[0034] The microgravure coating machine 7 is installed at the top inside the carbon layer coating area 8, and is located on top of the fiber aggregate 5.

[0035] Using the above structure: poly(p-phenylene terephthalamide) Kevlar is electrospun into aramid fiber aggregates with a porosity controlled at 10-90%; a layer of conductive carbon-based slurry is coated on both sides of the poly(p-phenylene terephthalamide) Kevlar fiber aggregates; after the slurry dries, it is pressurized to form a composite current collector. The composite current collector serves as the negative electrode current collector for lithium-ion secondary batteries, improving battery energy density; reducing battery internal resistance; improving battery rate performance and cycle life; and enhancing battery safety performance.

[0036] Please see Figure 1 A drying device 9 is provided on the right side of the carbon layer coating area 8. The fiber aggregate 5 penetrates the interior of the drying device 9 and is dried using the drying device 9. The drying temperature is 60-100℃ and the drying time is 0.5-2min. After drying, the thickness of the single functional layer is controlled at 0.2-5μm.

[0037] Please see Figure 1 A roller pressing device 10 is provided on the right side of the drying equipment 9. The fiber aggregate 5 passes through the interior of the roller pressing device 10, and the roller pressing device 10 rolls the fiber aggregate 5.

[0038] Please see Figure 1 A take-up shaft 11 is provided on the right side of the roller pressing equipment 10. The surface of the take-up shaft 11 is wound around the right end of the fiber aggregate 5. The take-up shaft 11 is used to drive the take-up of the fiber aggregate 5.

[0039] Please see Figure 1 A collection tank 6 is installed at the bottom of the middle of the inner side of the carbon layer coating area 8. The collection tank 6 is located at the bottom of the fiber aggregate 5 and the microgravure coating machine 7. The collection tank 6 is used to collect the liquid that falls out of the microgravure coating machine 7.

[0040] Please see Figure 1 The top of the fiber aggregate collecting curtain 4 is attached to the left end of the surface of the fiber aggregate 5. The fiber aggregate collecting curtain 4 is used to assist in the production of the fiber aggregate 5.

[0041] The operating steps of this utility model are as follows: Preparation of conductive slurry: Dry mix 30 kg of conductive agent, binder, and dispersant in a 200L V-type mixer for 50 min, with a mass ratio of 98.5:1.0:0.5; Transfer the mixture to a 600L slurry mixing tank, add the organic solvent evenly in three portions, and after each addition of water, maintain a stirring speed of 40 r / min, a dispersion disc linear velocity of 80 m / s, and a running time of 60 min; Obtain a conductive slurry with a solid content of 8%; The conductive agent is acetylene black and carbon nanotubes, with a mass ratio of 2:8; The binder is CMC; The dispersant is polyvinylpyrrolidone;

[0042] Fiber weaving chamber: Inside the fiber weaving chamber, in the melt spinning device 1, the melt spinning temperature of poly(p-phenylene terephthalamide) is set in the range of 450-520℃, the diameter of the spun fiber is between 0.2-0.5μm, and the spinning speed is 1-10 m / min. The fibers flowing out from the melt spinning device 1 are treated by the electrostatic adsorption device 3 under the action of electrostatic action, adsorption action and their own temperature, and the transfer shaft 2 and fiber aggregate collection curtain 4 to form fiber aggregates 5 with a porosity of 1-90%. The electrostatic spinning voltage is 20-50KV, and the adsorption wind speed is -0.05MPa to -0.1MPa.

[0043] In carbon coating area 8, the slurry is coated onto fiber aggregate 5 in microgravure coating machine 7. The remaining material is collected in collection tank 6. The thickness of a single wet film is controlled at 3-10μm, the coating speed is 20-100m / min, and the film is dried using drying equipment 9 at a drying temperature of 60-100℃ for 0.5-2min. After drying, the thickness of a single functional layer is controlled at 0.2-5μm, and the belt speed is 10-20m / min.

[0044] The composite current collector obtained in the electrostatic adsorption device 3 is rolled by the hot roller of the rolling equipment 10 at a rolling pressure of 1-10 MPa and a hot roller temperature of 300-500℃ to obtain the final composite current collector, which is then wound up by the winding shaft 11.

[0045] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A device for preparing a composite current collector for a lithium-ion secondary battery negative electrode, characterized in that, include Fiber weaving room; Melt spinning device (1), which is installed at the top of the fiber weaving chamber; Electrostatic adsorption device (3) is installed in the middle of the fiber weaving chamber; Transfer shaft (2), four transfer shafts (2) are provided, and the transfer shafts (2) are rotatably connected to the side of the fiber weaving chamber; Fiber aggregate collection curtain (4) is driven to the surface of four transfer shafts (2); Fiber aggregate (5) is produced at the outlet of the melt spinning device (1); Carbon layer coated area (8) is disposed around the fiber aggregate (5); Microgravure coating machine (7) is installed at the top inside the carbon layer coating area (8) and is located on top of the fiber aggregate (5).

2. The equipment for preparing a composite current collector for a lithium-ion secondary battery negative electrode according to claim 1, characterized in that, A drying device (9) is provided on the right side of the carbon layer coating area (8), and the fiber aggregate (5) penetrates the interior of the drying device (9).

3. The equipment for preparing a composite current collector for a lithium-ion secondary battery negative electrode according to claim 2, characterized in that, A roller pressing device (10) is provided on the right side of the drying device (9), and the fiber aggregate (5) penetrates the interior of the roller pressing device (10).

4. The equipment for preparing a composite current collector for a lithium-ion secondary battery negative electrode according to claim 3, characterized in that, A take-up shaft (11) is provided on the right side of the roller pressing device (10), and the surface of the take-up shaft (11) is wound around the right end of the fiber aggregate (5).

5. The equipment for preparing a composite current collector for a lithium-ion secondary battery negative electrode according to claim 4, characterized in that, A collection trough (6) is installed at the bottom of the inner middle of the carbon layer coating area (8). The collection trough (6) is located at the bottom of the fiber aggregate (5) and the microgravure coating machine (7).

6. The equipment for preparing a composite current collector for a lithium-ion secondary battery negative electrode according to claim 1, characterized in that, The top of the fiber aggregate collecting curtain (4) is attached to the left end of the surface of the fiber aggregate (5).

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