A novel positive electrode sheet and preparation method thereof
By synchronously coating carbon powder and positive electrode active slurry with a double cavity and double lips coating die head during the manufacturing process of the positive electrode sheet, and fibrillation of PTFE and carbon black, the adverse phenomena of carbon coating aluminum foil in the manufacturing process are solved, and a more uniform coating and better conductivity are achieved, cost loss is reduced and the circulation performance of the battery is improved.
Patent Information
- Application Number
- CN202411991603.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-04-08
AI Technical Summary
During the manufacturing process, the carbon-coated aluminum foil of the existing positive electrode sheet is prone to poor phenomena such as uneven thickness of the carbon coating layer, inconsistent color difference, oil droplets, empty foil coating, poor adhesion, etc., resulting in high cost loss and unstable product quality.
The carbon powder and the positive electrode active slurry were synchronized by using a double cavity and double lips coating die head to the substrate, and a new positive electrode sheet was prepared after drying and winding. This method improves the dispersed state of carbon black and the adhesion of active substances through fibrosis treatment between PTFE and carbon black, and enhances the conductivity.
The cost of poor incoming materials is effectively controlled, the uniformity and adhesion of the carbon coating layer is improved, the conductivity is enhanced, the corrosion of organic solvent residues on the aluminum foil substrate is reduced, the circulation performance of the battery is improved, and the advantages of low cost loss and good product quality are provided.
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Figure CN119786534A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of electrode materials, and more specifically, to a novel positive electrode sheet and a preparation method thereof. Background Art
[0002] At present, new energy lithium batteries are in a process of rapid development. The battery is mainly composed of positive electrode sheets, negative electrode sheets, diaphragms, and aluminum shells (steel shells). The positive electrode sheets are mainly composed of active materials, conductive agents, binders, and current collectors. Among them, the positive electrode sheets used by various battery companies in the current market mainly use carbon-coated aluminum foil that has been formed by raw material manufacturers, and then the positive electrode slurry is coated on the carbon-coated aluminum foil, and then the electrode sheet is dried. When the raw material manufacturer manufactures the carbon-coated aluminum foil, the mixed conductive slurry is coated on the substrate, dried, rolled, cut into plates, and then sent to downstream battery manufacturers.
[0003] When raw material manufacturers make carbon-coated aluminum foil, there may be manufacturing process and other reasons that cause uneven thickness of the carbon-coated layer on the formed carbon-coated aluminum foil, inconsistent color difference, oil droplets, empty foil coating, poor adhesion and other undesirable phenomena. In addition, the formed carbon-coated aluminum foil must strictly ensure the sealing of the packaging during transportation. Poor carbon-coated aluminum foil and production environment control will cause great cost losses to the foil factory. For battery manufacturers, it is difficult to control the qualification of the required carbon-coated aluminum foil, and it will increase the cost of the battery. Summary of the invention
[0004] In order to further improve the product quality of carbon-coated aluminum foil, the present application provides a new positive electrode plate and a preparation method thereof.
[0005] In the first aspect, the present application provides a novel positive electrode plate, which adopts the following technical solution:
[0006] A novel positive electrode plate comprises a substrate, wherein a carbon coating layer and a positive electrode slurry layer are simultaneously coated on the surface of the substrate.
[0007] Preferably, the thickness of the substrate is 6-20 μm.
[0008] Preferably, the carbon coating layer consists of PTFE and carbon black.
[0009] Preferably, the mass fraction of PTFE in the carbon coating layer is 5-10%.
[0010] Preferably, the mass fraction of carbon black in the carbon coating layer is 90-95%.
[0011] Preferably, the PTFE and carbon black are subjected to fibrillation treatment.
[0012] Preferably, the carbon coating layer has a thickness of 1-3 μm.
[0013] Preferably, the positive electrode slurry layer is composed of slurry dry powder and a solvent, and the slurry dry powder is composed of lithium iron phosphate, a conductive agent, and a binder.
[0014] Preferably, the mass fraction of lithium iron phosphate in the slurry dry powder is 90-97%;
[0015] And / or, the mass fraction of the conductive agent in the slurry dry powder is 1-4%;
[0016] And / or, the mass fraction of the binder in the slurry dry powder is 2-6%;
[0017] And / or, the mass fraction of dry slurry powder in the positive electrode slurry layer is 50-70%;
[0018] And / or, the mass fraction of the solvent in the positive electrode slurry layer is 30-50%.
[0019] In the second aspect, the present application provides a novel method for preparing a positive electrode pole piece, comprising the following steps: using a double-cavity double-lip coating die head to simultaneously coat carbon-coated powder and positive electrode active slurry onto a substrate, and obtaining the result after drying and winding.
[0020] In summary, this application has the following beneficial effects:
[0021] 1. This application simultaneously coats the carbon-coated powder and the positive electrode active slurry on the substrate, which can effectively control the cost of defective incoming materials. In addition, the original substrate is used, and the initial substrate is cheaper than the carbon-coated aluminum foil, and can be effectively controlled.
[0022] 2. In this application, PTFE and carbon black fibrillation treatment are preferably used as the material of the carbon coating layer, which can effectively improve the dispersion state of carbon black, distribute it more evenly on the substrate, improve the adhesion between the active substance and the substrate, and increase the conductivity. In addition, the carbon coating layer does not use conventional organic solvents or deionized water as solvents, which can reduce the corrosion of residual organic solvents such as NMP to the aluminum foil substrate, and also enhance the adhesion between the carbon coating layer and the substrate, and also improve the adhesion between the positive electrode slurry layer and the carbon coating layer, which greatly improves the cycle performance of the battery.
[0023] 3. The new positive electrode plate prepared by the preparation method of the present application has the advantages of low cost loss and good product quality. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a schematic diagram of the structure of the new positive electrode plate of Examples 1-3 of the present application. DETAILED DESCRIPTION
[0025] The present application is further described in detail below in conjunction with embodiments.
[0026] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.
[0027] Example 1
[0028] The new positive electrode plate of this embodiment, such as Figure 1 As shown, it includes a substrate, and a carbon coating layer and a positive electrode slurry layer are simultaneously coated on the surface of the substrate.
[0029] The method for preparing the novel positive electrode sheet of this embodiment comprises the following steps:
[0030] The PTFE and acetylene black are uniformly mixed to obtain a carbon-coated powder;
[0031] The lithium iron phosphate, the conductive agent and the binder are mixed evenly to obtain a slurry dry powder, and then the slurry dry powder is mixed evenly with NMP to obtain a positive electrode active slurry;
[0032] Take the carbon coating layer powder and the positive electrode active slurry, and use a double-cavity double-lip coating die to simultaneously coat the carbon coating layer powder and the positive electrode active slurry on the substrate; the dry carbon coating layer powder is transported from the lower lip of the lower cavity of the coating die and sprayed on the foil current collector, and the positive electrode active slurry is sprayed on the upper lip of the cavity of the die; after the carbon coating layer and the active layer slurry are coated on the foil, the upper slurry is dried in an oven, and the product is rolled up after drying at the tail of the coating machine.
[0033] The substrate is aluminum foil with a thickness of 6 μm and a grade of 1060.
[0034] The mass fraction of PTFE in the carbon coating layer is 5%. The mass fraction of carbon black in the carbon coating layer is 95%, and the carbon black is acetylene black. The thickness of the carbon coating layer is 1 μm.
[0035] The mass fraction of lithium iron phosphate in the slurry dry powder is 97%, the mass fraction of the conductive agent in the slurry dry powder is 1%, and the mass fraction of the binder in the slurry dry powder is 2%.
[0036] The mass fraction of the dry powder in the positive electrode slurry layer is 50%. The mass fraction of the solvent in the positive electrode slurry layer is 50%, and the solvent is NMP.
[0037] Example 2
[0038] The new positive electrode plate of this embodiment, such as Figure 1 As shown, it includes a substrate, and a carbon coating layer and a positive electrode slurry layer are simultaneously coated on the surface of the substrate.
[0039] The method for preparing the novel positive electrode sheet of this embodiment comprises the following steps:
[0040] The PTFE and acetylene black are uniformly mixed to obtain a carbon-coated powder;
[0041] The lithium iron phosphate, the conductive agent and the binder are mixed evenly to obtain a slurry dry powder, and then the slurry dry powder is mixed evenly with NMP to obtain a positive electrode active slurry;
[0042] Take the carbon coating layer powder and the positive electrode active slurry, and use a double-cavity double-lip coating die to simultaneously coat the carbon coating layer powder and the positive electrode active slurry on the substrate; the dry carbon coating layer powder is transported from the lower lip of the lower cavity of the coating die and sprayed on the foil current collector, and the positive electrode active slurry is sprayed on the upper lip of the cavity of the die; after the carbon coating layer and the active layer slurry are coated on the foil, the upper slurry is dried in an oven, and the product is rolled up after drying at the tail of the coating machine.
[0043] The substrate is aluminum foil with a thickness of 20 μm and a brand of 1235.
[0044] The mass fraction of PTFE in the carbon coating layer is 10%. The mass fraction of carbon black in the carbon coating layer is 90%, and the carbon black is acetylene black. The thickness of the carbon coating layer is 3 μm.
[0045] The mass fraction of lithium iron phosphate in the slurry dry powder is 90%, the mass fraction of the conductive agent in the slurry dry powder is 4%, and the mass fraction of the binder in the slurry dry powder is 6%.
[0046] The mass fraction of the dry powder in the positive electrode slurry layer is 70%. The mass fraction of the solvent in the positive electrode slurry layer is 30%, and the solvent is NMP.
[0047] Example 3
[0048] The new positive electrode plate of this embodiment, such as Figure 1 As shown, it includes a substrate, and a carbon coating layer and a positive electrode slurry layer are simultaneously coated on the surface of the substrate.
[0049] The method for preparing the novel positive electrode sheet of this embodiment comprises the following steps:
[0050] The PTFE and acetylene black are mixed evenly and then subjected to fibrillation treatment to obtain a carbon-coated powder;
[0051] The lithium iron phosphate, the conductive agent and the binder are mixed evenly to obtain a slurry dry powder, and then the slurry dry powder is mixed evenly with NMP to obtain a positive electrode active slurry;
[0052] Take the carbon coating layer powder and the positive electrode active slurry, and use a double-cavity double-lip coating die to simultaneously coat the carbon coating layer powder and the positive electrode active slurry on the substrate; the dry carbon coating layer powder is transported from the lower lip of the lower cavity of the coating die and sprayed on the foil current collector, and the positive electrode active slurry is sprayed on the upper lip of the cavity of the die; after the carbon coating layer and the active layer slurry are coated on the foil, the upper slurry is dried in an oven, and the product is rolled up after drying at the tail of the coating machine.
[0053] The substrate is aluminum foil with a thickness of 10 μm and a grade of 1050.
[0054] The mass fraction of PTFE in the carbon coating layer is 5%. The mass fraction of carbon black in the carbon coating layer is 95%, and the carbon black is acetylene black. The thickness of the carbon coating layer is 2 μm.
[0055] The mass fraction of lithium iron phosphate in the slurry dry powder is 95%, the mass fraction of the conductive agent in the slurry dry powder is 2%, and the mass fraction of the binder in the slurry dry powder is 3%.
[0056] The mass fraction of the dry powder in the positive electrode slurry layer is 60%. The mass fraction of the solvent in the positive electrode slurry layer is 40%, and the solvent is NMP.
[0057] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.
Claims
1. A novel positive electrode plate, characterized in that: The invention comprises a substrate, the surface of which is simultaneously coated with a carbon coating layer and a positive electrode slurry layer.
2. A novel positive electrode plate according to claim 1, characterized in that: The thickness of the substrate is 6-20 μm.
3. A novel positive electrode plate according to claim 1, characterized in that: The carbon coating layer consists of PTFE and carbon black.
4. A novel positive electrode plate according to claim 3, characterized in that: The mass fraction of PTFE in the carbon coating layer is 5-10%.
5. A novel positive electrode plate according to claim 3, characterized in that: The mass fraction of carbon black in the carbon coating layer is 90-95%.
6. A novel positive electrode plate according to claim 3, characterized in that: The PTFE and carbon black are subjected to fibrillation treatment.
7. A novel positive electrode plate according to claim 1, characterized in that: The thickness of the carbon coating layer is 1-3 μm.
8. The novel positive electrode plate according to claim 1, characterized in that: The positive electrode slurry layer is composed of slurry dry powder and a solvent, and the slurry dry powder is composed of lithium iron phosphate, a conductive agent, and a binder.
9. A novel positive electrode plate according to claim 8, characterized in that: The mass fraction of lithium iron phosphate in the slurry dry powder is 90-97%; And / or, the mass fraction of the conductive agent in the slurry dry powder is 1-4%; And / or, the mass fraction of the binder in the slurry dry powder is 2-6%; And / or, the mass fraction of dry slurry powder in the positive electrode slurry layer is 50-70%; And / or, the mass fraction of the solvent in the positive electrode slurry layer is 30-50%.
10. A method for preparing a novel positive electrode sheet, characterized in that: The method comprises the following steps: using a double-cavity double-lip coating die head to simultaneously coat carbon-coated powder and positive electrode active slurry on a substrate, and then drying and rolling the substrate to obtain the product.