Pole piece and lithium-ion battery

Abstract

The present invention belongs to the technical field of lithium-ion batteries, and relates to an electrode sheet and a lithium-ion battery, which include a plastic film, a negative electrode metal coating, a positive electrode metal coating, a negative electrode active material, a positive electrode active material, a negative electrode tab and a positive electrode tab. The negative electrode metal coating covers the upper surface of the plastic film and wraps the first side edge of the plastic film, the positive electrode metal coating covers the lower surface of the plastic film and wraps the second side edge of the plastic film, the negative electrode active material is coated on the upper surface of the negative electrode metal coating, and the positive electrode active material is coated on the lower surface of the positive electrode metal coating; the negative electrode metal coating, the plastic film and the positive electrode metal coating are stacked to form a bipolar current collector. The electrode sheet of the present application can eliminate the risk of short circuit between the positive and negative electrodes, and only the alignment of the entire electrode sheet needs to be controlled during lamination; only one type of electrode sheet is used during lamination, which simplifies the process flow and significantly improves the lamination speed; it is light in weight and high in energy density.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and relates to a pole piece and a lithium-ion battery. 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 products and electric vehicles. With the development of new energy vehicles, people have put forward higher requirements for the cruising 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 increasing the energy density, and can also reduce the production cost of the battery, and has 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 thickness of the current collector 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 short circuit of the battery. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to provide a pole piece and a lithium-ion battery for the problem that the existing current collector may cause a short circuit of the battery due to poor welding during the assembly process.

[0006] To solve the above technical problem, on the one hand, the present invention provides a pole piece. The pole piece includes a plastic film, a negative metal coating, a positive metal coating, a negative active material, a positive active material, a negative pole tab and a positive pole tab. The negative metal coating covers the upper surface of the plastic film and wraps the first side edge of the plastic film. The positive metal coating covers the lower surface of the plastic film and wraps the second side edge of the plastic film. The negative active material is coated on the upper surface of the negative metal coating, and the positive active material is coated on the lower surface of the positive metal coating; the negative metal coating, the plastic film and the positive metal coating are stacked as a bipolar current collector.

[0007] The negative pole tab is connected to the first side edge of the negative metal coating, the positive pole tab is connected to the second side edge of the positive metal coating, and the negative pole tab and the positive pole tab are arranged opposite to each other.

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

[0009] A second stepped surface is provided on the lower surface of the second side of the plastic film, and the negative 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;

[0011] The negative electrode tab is a copper foil sheet, and the positive electrode tab is an aluminum foil sheet.

[0012] Optionally, the plastic film is a PET film.

[0013] Optionally, the thickness of the plastic film is 1 - 50 microns;

[0014] 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.

[0015] Optionally, the negative metal coating is covered on the upper surface of the plastic film by evaporation plating; the positive metal coating is covered on the lower surface of the plastic film by evaporation plating.

[0016] Optionally, separators are provided on both the upper and lower surfaces of the electrode sheet.

[0017] Optionally, the upper surface of the separator covers the positive active material of the upper electrode sheet, and the lower surface of the separator covers the negative active material of the lower electrode sheet.

[0018] Optionally, the upper surface of the separator covers the negative active material of the upper electrode sheet, and the lower surface of the separator covers the positive active material of the lower electrode sheet.

[0019] The pole piece provided by the embodiment of the present invention includes a plastic film, a negative electrode metal coating, a positive electrode metal coating, a negative electrode active material, a positive electrode active material, a negative electrode tab and a positive electrode tab. The negative electrode metal coating covers the upper surface of the plastic film and wraps the first side edge of the plastic film. The positive electrode metal coating covers the lower surface of the plastic film and wraps the second side edge of the plastic film. The negative electrode active material is coated on the upper surface of the negative electrode metal coating, and the positive electrode active material is coated on the lower surface of the positive electrode metal coating. The negative electrode metal coating, the plastic film and the positive electrode metal coating are stacked to form a bipolar current collector. The negative electrode tab is connected to the first side edge of the negative electrode metal coating, and the positive electrode tab is connected to the second side edge of the positive electrode metal coating. The negative electrode tab and the positive electrode tab are arranged oppositely. For the pole piece of the present application, only the alignment of the entire pole piece needs to be controlled during lamination; only one type of pole piece is used during lamination, simplifying the process flow and significantly improving the lamination speed; metal burrs can be eliminated during cutting; it is light in weight; and it has a high energy density.

[0020] On the other hand, the embodiment of the present invention also provides a lithium-ion battery, which includes the above-mentioned pole piece. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the pole piece provided by an embodiment of the present invention.

[0022] The reference numerals in the specification are as follows:

[0023] 1. Negative electrode tab; 2. Negative electrode metal coating; 3. Separator; 4. Negative electrode active material; 5. Plastic film; 6. Positive electrode tab; 7. Positive electrode active material; 8. Positive electrode metal coating. Detailed Embodiments

[0024] 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 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.

[0025] As Figure 1As shown in the figure, the electrode provided by the embodiment of the present invention includes a plastic film 5, a negative metal coating 2, a positive metal coating 8, a negative active material 4, a positive active material 7, a negative electrode tab 1 and a positive electrode tab 6. The negative metal coating 2 covers the upper surface of the plastic film 5 and wraps the first side edge of the plastic film 5. The positive metal coating 8 covers the lower surface of the plastic film 5 and wraps the second side edge of the plastic film 5. The negative active material 4 is coated on the upper surface of the negative metal coating 2, and the positive active material 7 is coated on the lower surface of the positive metal coating 8. The negative metal coating 2, the plastic film 5 and the positive metal coating 8 are stacked as a bipolar current collector.

[0026] The negative electrode tab 1 is connected to the first side edge of the negative metal coating 2, the positive electrode tab 6 is connected to the second side edge of the positive metal coating 8, and the negative electrode tab 1 and the positive electrode tab 6 are arranged oppositely. Only one type of electrode is used during lamination, which simplifies the process flow and significantly improves the lamination speed.

[0027] In one embodiment, a first stepped surface (not shown in the figure) is provided on the upper surface of the first side of the plastic film 5, and the negative metal coating 2 covers the first stepped surface.

[0028] A second stepped surface (not shown in the figure) is provided on the lower surface of the second side of the plastic film 5, and the negative metal coating 2 covers the second stepped surface.

[0029] In one embodiment, the negative metal coating 2 is a copper coating, and the positive metal coating 8 is an aluminum coating.

[0030] The negative electrode tab 1 is a copper foil sheet, and the positive electrode tab 6 is an aluminum foil sheet.

[0031] In one embodiment, the plastic film 5 is a PET film.

[0032] In one embodiment, the thickness of the plastic film 5 is 1 - 50 microns.

[0033] 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.

[0034] In one embodiment, the negative metal coating 2 is covered on the upper surface of the plastic film 5 by means of evaporation coating.

[0035] The positive metal coating 8 is covered on the lower surface of the plastic film 5 by means of evaporation coating.

[0036] In one embodiment, separators 3 are provided on both the upper and lower surfaces of the electrode.

[0037] In one embodiment, the upper surface of the separator 3 covers the positive active material 7 of the upper electrode plate, and the lower surface of the separator 3 covers the negative active material 4 of the lower electrode plate.

[0038] In one embodiment, the upper surface of the separator 3 covers the negative active material 4 of the upper electrode plate, and the lower surface of the separator 3 covers the positive active material 7 of the lower electrode plate.

[0039] The stacking order of the electrode plates in the present invention can be reversed.

[0040] For the electrode plate according to an embodiment of the present invention, the negative metal coating covers the upper surface of the plastic film and wraps the first side edge of the plastic film, the positive metal coating covers the lower surface of the plastic film and wraps the second side edge of the plastic film, the negative active material is coated on the upper surface of the negative metal coating, and the positive active material is coated on the lower surface of the positive metal coating; the negative metal coating, the plastic film and the positive metal coating are stacked to form a bipolar current collector; the negative electrode tab is connected to the first side edge of the negative metal coating, the positive electrode tab is connected to the second side edge of the positive metal coating, and the negative electrode tab and the positive electrode tab are arranged oppositely. The current collector of the present application can eliminate the risk of short circuit between the positive and negative electrodes. When stacking the sheets, only the alignment of the entire electrode plate needs to be controlled; only one type of electrode plate is used during sheet stacking, which simplifies the process flow and significantly improves the sheet stacking speed; metal burrs can be eliminated during cutting; it is light in weight; and it has a high energy density.

[0041] In addition, an embodiment of the present invention further provides a lithium-ion battery, which includes the electrode plate of the above embodiment.

[0042] The above are only the preferred embodiments of the present invention, and are not intended 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 pole piece, characterized in that, It includes a plastic film, a negative metal coating, a positive metal coating, a negative active material, a positive active material, a negative tab and a positive tab. The negative metal coating covers the upper surface of the plastic film and wraps the first side edge of the plastic film. The positive metal coating covers the lower surface of the plastic film and wraps the second side edge of the plastic film. The negative active material is coated on the upper surface of the negative metal coating, and the positive active material is coated on the lower surface of the positive metal coating. The negative metal coating, the plastic film and the positive metal coating are stacked to form a bipolar current collector. The negative tab is connected to the first side edge of the negative metal coating, and the positive tab is connected to the second side edge of the positive metal coating. The negative tab and the positive tab are arranged opposite to each other. A first stepped surface is provided on the upper surface of the first side of the plastic film, and the negative metal coating covers the first stepped surface. A second stepped surface is provided on the lower surface of the second side of the plastic film, and the negative metal coating covers the second stepped surface.

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

3. The pole piece according to claim 1, characterized in that, The plastic film is a PET film.

4. The pole piece 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 electrode sheet according to any one of claims 1-3, characterized in that The negative metal coating is covered on the upper surface of the plastic film by means of evaporation coating. The positive metal coating is covered on the lower surface of the plastic film by means of evaporation coating.

6. A lithium-ion battery, characterized in that, It includes a plurality of electrode plates according to any one of claims 1 - 5. Diaphragms are provided on both the upper and lower surfaces of the electrode plates.

7. The lithium ion battery according to claim 6, wherein, The upper surface of the diaphragm covers the positive active material of the upper - layer electrode plate, and the lower surface of the diaphragm covers the negative active material of the lower - layer electrode plate.

8. The lithium ion battery according to claim 6, wherein, The upper surface of the diaphragm covers the negative active material of the upper - layer electrode plate, and the lower surface of the diaphragm covers the positive active material of the lower - layer electrode plate.

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