A battery cell

Abstract

The present invention belongs to the technical field of lithium-ion batteries and relates to an electric core, comprising a wound core, a negative electrode tab and a positive electrode tab. The wound core is a multi-layer structure formed by winding a bipolar electrode sheet and a separator stacked on one surface of the bipolar electrode sheet. The bipolar electrode sheet includes a plastic film, a negative metal coating, a positive metal coating, a negative active material and a positive active material. The negative metal coating covers one surface of the plastic film and wraps the first end of the plastic film. The positive metal coating covers the other surface of the plastic film and wraps the second end of the plastic film. The negative active material is coated on the surface of the negative metal coating away from the plastic film, and the positive active material is coated on the surface of the positive metal coating away from the plastic film. For the electric core of the present application, the wound core only needs to be wound with one bipolar electrode sheet and one layer of separator, which simplifies the process flow, is light in weight, and has a high energy density.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries and relates to an electrode core. Background Art

[0002] Lithium-ion batteries have the advantages of large capacity, high working voltage, strong charge retention ability, and high safety, and have been widely used in consumer electronics and electric vehicles. With the development of new energy vehicles, people have put forward higher requirements for the driving range of new energy vehicles. Therefore, improving the energy density of lithium-ion batteries is the main development direction of lithium-ion batteries. Reducing the weight of the current collector as one of the directions to improve the lithium-ion energy density does not bring safety risks while improving the energy density, and can also reduce the production cost of the battery, having a broader application prospect.

[0003] At present, the positive current collector of mainstream lithium-ion batteries is aluminum foil, and the negative current collector is copper foil. When the thickness of the metal foil is reduced to a certain extent, its mechanical strength decreases, and the processing difficulty also increases greatly. In order to ensure its mechanical strength and reduce the thickness, a patent has proposed a method of reducing the current collector thickness by plating copper or aluminum on a plastic film.

[0004] Although this method plays a role in reducing the thickness, since the plastic film will have an adverse effect on the welding during the assembly process, it may cause a battery short circuit. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: aiming at the problem that the existing plastic film will have an adverse effect on the welding during the assembly process and may cause a battery short circuit, to provide an electrode core.

[0006] To solve the above technical problem, the present invention provides an electrode core. The electrode core includes a wound core, a negative electrode tab, and a positive electrode tab. The wound core is a multi-layer structure formed by winding a bipolar electrode sheet and a separator stacked on one side surface of the bipolar electrode sheet. The bipolar electrode sheet includes a plastic film, a negative metal coating, a positive metal coating, a negative active material, and a positive active material. The negative metal coating covers one side surface of the plastic film and wraps the first end of the plastic film. The positive metal coating covers the other side surface of the plastic film and wraps the second end of the plastic film. The negative active material is coated on the side surface of the negative metal coating facing away from the plastic film, and the positive active material is coated on the side surface of the positive metal coating facing away from the plastic film. The negative metal coating, the plastic film, and the positive metal coating are stacked and wound into a bipolar current collector, and the negative metal coating is insulated from the positive metal coating;

[0007] The negative electrode tab is connected to the first end of the negative metal coating, and the positive electrode tab is connected to the first end of the positive metal coating.

[0008] Optionally, a first stepped surface is provided on one side surface of the plastic film, and the negative metal coating covers the first stepped surface;

[0009] A second stepped surface is provided on the other side surface of the plastic film, and the positive metal coating covers the second stepped surface.

[0010] Optionally, the negative metal coating is a copper coating, and the positive metal coating is an aluminum coating; the negative electrode tab is a copper foil sheet, and the positive electrode tab is an aluminum foil sheet.

[0011] Optionally, the plastic film is a PET film.

[0012] Optionally, the thickness of the plastic film is 1 - 50 microns;

[0013] The thickness of the negative metal coating is 0.5 - 1 micron, and the thickness of the positive metal coating is 0.5 - 1 micron.

[0014] Optionally, the negative metal coating is covered on one side surface of the plastic film by means of evaporation coating;

[0015] The positive metal coating is covered on the other side surface of the plastic film by means of evaporation coating.

[0016] Optionally, the separator is attached to the positive active material.

[0017] Optionally, the separator is attached to the negative active material.

[0018] The battery cell provided by an embodiment of the present invention includes a wound core, a negative electrode tab, and a positive electrode tab. The wound core is a multi-layer structure formed by winding a bipolar electrode sheet and a separator stacked on one side surface of the bipolar electrode sheet. The bipolar electrode sheet includes a plastic film, a negative metal coating, a positive metal coating, a negative active material, and a positive active material. The negative metal coating covers one side surface of the plastic film and wraps the first end of the plastic film. The positive metal coating covers the other side surface of the plastic film and wraps the first end of the plastic film. The negative active material is coated on the side surface of the negative metal coating facing away from the plastic film. The positive active material is coated on the side surface of the positive metal coating facing away from the plastic film. The negative metal coating, the plastic film, and the positive metal coating are stacked and wound into a bipolar current collector, and the negative metal coating and the positive metal coating are insulated from each other. The negative electrode tab is connected to the first end of the negative metal coating, and the positive electrode tab is connected to the first end of the positive metal coating. The negative electrode tab and the positive electrode tab are located outside the wound core. For the battery cell of the present application, the wound core only needs to be wound with one bipolar electrode sheet and one layer of separator, which simplifies the process flow, has a light weight, and a high energy density. Description of the Drawings

[0019] Figure 1 is a schematic diagram of a bipolar electrode sheet of a battery cell provided by an embodiment of the present invention;

[0020] Figure 2 is a schematic diagram of a bipolar electrode sheet and a separator of a battery cell provided by the first embodiment of the present invention;

[0021] Figure 3 is a schematic diagram of a bipolar electrode sheet and a separator of a battery cell provided by the second embodiment of the present invention;

[0022] Figure 4 is a schematic diagram of a battery cell provided by an embodiment of the present invention.

[0023] The reference numerals in the specification are as follows:

[0024] 10, bipolar electrode sheet; 1, negative electrode tab; 2, negative metal coating; 3, separator; 4, negative active material; 5, plastic film; 6, positive electrode tab; 7, positive active material; 8, positive metal coating. Detailed Embodiments

[0025] In order to make the technical problems, technical solutions, and beneficial effects solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] As Figures 1 to 2As shown in the figure, the battery cell provided by the embodiment of the present invention includes a wound core, a negative electrode tab 1 and a positive electrode tab 6. The wound core is a multi-layer structure formed by winding a bipolar electrode sheet 10 and a separator 3 stacked on one side surface of the bipolar electrode sheet 10. The bipolar electrode sheet 10 includes a plastic film 5, a negative metal coating 2, a positive metal coating 8, a negative active material 4 and a positive active material 7. The negative metal coating 2 covers one side surface of the plastic film 5 and wraps the first end of the plastic film 5. The positive metal coating 8 covers the other side surface of the plastic film 5 and wraps the second end of the plastic film 5. The negative active material 4 is coated on the side surface of the negative metal coating 2 facing away from the plastic film 5. The positive active material 7 is coated on the side surface of the positive metal coating 8 facing away from the plastic film 5. The negative metal coating 2, the plastic film 5 and the positive metal coating 8 are stacked and wound into a bipolar current collector, and the negative metal coating 2 and the positive metal coating 8 are insulated from each other.

[0027] The negative electrode tab 1 is connected to the first end of the negative metal coating 2, and the positive electrode tab 6 is connected to the first end of the positive metal coating 8.

[0028] In one embodiment, a first stepped surface (not shown in the figure) is provided on one side surface of the plastic film 5, and the negative metal coating 2 covers the first stepped surface.

[0029] A second stepped surface (not shown in the figure) is provided on the other side surface of the plastic film 5, and the positive metal coating 8 covers the second stepped surface.

[0030] In one embodiment, the negative metal coating 2 is a copper coating, and the positive metal coating 8 is an aluminum coating.

[0031] The negative electrode tab 1 is a copper foil sheet, and the positive electrode tab 6 is an aluminum foil sheet.

[0032] Optionally, the negative electrode tab 1 is not limited to copper and can also be other metals or alloy elements. The positive electrode tab 6 is not limited to aluminum and can also be other metals or alloy elements.

[0033] In one embodiment, the plastic film 5 is a PET film.

[0034] Optionally, the material of the plastic film 5 includes but is not limited to PET, OPP, PI, CPP, PVC, etc.

[0035] In one embodiment, the thickness of the plastic film 5 is 1-50 microns.

[0036] The thickness of the negative metal coating 2 is 0.5-1 micron, and the thickness of the positive metal coating 8 is 0.5-1 micron.

[0037] In one embodiment, the negative electrode metal coating 2 is covered on one side surface of the plastic film 5 by means of evaporation coating.

[0038] The positive electrode metal coating 8 is covered on the other side surface of the plastic film 5 by means of evaporation coating.

[0039] In one embodiment, the separator 3 is attached to the positive electrode active material 7.

[0040] In one embodiment, the separator 3 is attached to the negative electrode active material 4.

[0041] Optionally, when winding, the plastic film 5 can be located outside the winding core or wrapped inside the winding core.

[0042] For the battery cell according to the embodiment of the present invention, the winding core is a multi-layer structure formed by winding a bipolar electrode plate and a separator stacked on one side surface of the bipolar electrode plate. The bipolar electrode plate includes a plastic film, a negative electrode metal coating, a positive electrode metal coating, a negative electrode active material and a positive electrode active material. The negative electrode metal coating covers one side surface of the plastic film and covers the first end of the plastic film. The positive electrode metal coating covers the other side surface of the plastic film and covers the first end of the plastic film. The negative electrode active material is coated on the side surface of the negative electrode metal coating facing away from the plastic film. The positive electrode active material is coated on the side surface of the positive electrode metal coating facing away from the plastic film. The negative electrode metal coating, the plastic film and the positive electrode metal coating are stacked and wound into a bipolar current collector. The negative electrode metal coating is insulated from the positive electrode metal coating. The negative electrode tab is connected to the first end of the negative electrode metal coating. The positive electrode tab is connected to the first end of the positive electrode metal coating. The negative electrode tab and the positive electrode tab are located outside the winding core. For the battery cell of the present application, the winding core only needs one bipolar electrode plate and one layer of separator to be wound, which simplifies the process flow, is light in weight, and has a high energy density.

[0043] The above are only the preferred embodiments of the present invention, and are not used to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A battery cell, characterized in that, It includes a core, a negative pole tab and a positive pole tab. The core is a multi-layer structure formed by winding a bipolar electrode sheet and a separator stacked on one side surface of the bipolar electrode sheet. The bipolar electrode sheet includes a plastic film, a negative metal coating, a positive metal coating, a negative active material and a positive active material. The negative metal coating covers one side surface of the plastic film and wraps the first end of the plastic film. The positive metal coating covers the other side surface of the plastic film and wraps the second end of the plastic film. The negative active material is coated on the side surface of the negative metal coating facing away from the plastic film. The positive active material is coated on the side surface of the positive metal coating facing away from the plastic film. The negative metal coating, the plastic film and the positive metal coating are stacked and wound into a bipolar current collector, and the negative metal coating is insulated from the positive metal coating; The negative pole tab is connected to the first end of the negative metal coating, and the positive pole tab is connected to the first end of the positive metal coating; One side surface of the plastic film is provided with a first stepped surface, and the first stepped surface is arranged at one end of the plastic film close to the negative pole tab, and the negative metal coating covers the first stepped surface. The other side surface of the plastic film is provided with a second stepped surface, and the second stepped surface is arranged at one end of the plastic film close to the positive pole tab, and the positive metal coating covers the second stepped surface.

2. The battery cell according to claim 1, wherein, The negative metal coating is a copper coating, and the positive metal coating is an aluminum coating; The negative pole tab is a copper foil sheet, and the positive pole tab is an aluminum foil sheet.

3. The battery cell according to claim 1, wherein, The plastic film is a PET film.

4. The battery cell according to any one of claims 1-3, characterized in that, The thickness of the plastic film is 1-50 microns; The thickness of the negative metal coating is 0.5-1 micron, and the thickness of the positive metal coating is 0.5-1 micron.

5. The battery cell according to any one of claims 1-3, characterized in that The negative metal coating is covered on one side surface of the plastic film by means of evaporation coating; The positive metal coating is covered on the other side surface of the plastic film by means of evaporation coating.

6. The battery cell according to claim 1, wherein, The separator is attached to the positive active material.

7. The cell according to claim 1, characterized in that, The separator is attached to the negative active material.

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