Insulating film, pole group structure and battery cell

Abstract

The utility model belongs to the technical field of batteries, and discloses an insulating film, a pole group structure and a battery monomer, the insulating film comprises a first coating part and a second coating part, the first coating part is used for coating the bottom surface of a pole group, the second coating part surrounds and is fixed on the periphery of the first coating part, the second coating part is used for coating all side walls of the pole group, and the first coating part is used for coating the bottom surface of the pole group. The second coating part has plasticity and thermoplasticity, the insulating film can be used as a whole to coat the bottom surface and all side walls of the pole group, and after the pole group is coated, no splicing seam is formed in the insulating film, so that the leakproofness of the pole group coated by the insulating film is greatly improved, and a powerful guarantee can be provided for the insulativity between the pole group and a battery shell.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to an insulating film, electrode structure and battery cell. Background Technology

[0002] A battery cell includes a battery casing and electrode assembly, with the electrode assembly located inside the battery casing. To achieve insulation between the electrode assembly and the battery casing, the outer surface of the electrode assembly is usually insulated. Currently, there are two common methods: attaching insulating tape to the outer surface of the electrode assembly, or attaching insulating sheets to the outer surface of the electrode assembly.

[0003] However, attaching insulating tape to the outer surface of the electrode assembly requires splicing two adjacent pieces of insulating tape, and attaching insulating sheets also requires splicing two adjacent insulating sheets. As a result, seams are likely to appear at the splicing points, exposing the electrode assembly located in the seam area and failing to provide reliable insulation between the electrode assembly and the battery casing.

[0004] Therefore, there is an urgent need to propose an insulating film, electrode structure, and battery cell to solve the above-mentioned technical problems. Utility Model Content

[0005] The first objective of this invention is to provide an insulating film that can be used as a whole to cover the bottom surface and all sidewalls of the electrode assembly, and after the electrode assembly is covered, there are no seams on the insulating film.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] Insulating film, including:

[0008] The first covering part is used to cover the bottom surface of the electrode assembly;

[0009] The second covering portion surrounds and is fixed to the outer periphery of the first covering portion. The second covering portion is used to cover all the sidewalls of the electrode assembly, and the second covering portion is plastic and thermoplastic.

[0010] Optionally, the first coating portion is provided with a liquid permeable structure, through which the electrolyte can penetrate into the space between the first coating portion and the bottom surface of the electrode assembly.

[0011] Optionally, the plasticity of the first covering part is less than that of the second covering part.

[0012] Optionally, the first covering part is made of PP material.

[0013] Optionally, the second covering part is made of PVC material.

[0014] The second objective of this invention is to provide an electrode assembly structure that can significantly improve the tightness of the insulating film covering the electrode assembly.

[0015] To achieve this objective, the present invention adopts the following technical solution:

[0016] The electrode assembly structure includes an electrode assembly and the aforementioned insulating film. The bottom surface of the electrode assembly is covered by a first covering portion, and all sidewalls of the electrode assembly are covered by a second covering portion.

[0017] Optionally, the thickness of the first covering part is greater than the thickness of the second covering part.

[0018] Optionally, the thickness of the first covering part is 0.75mm-1.1mm, and the thickness of the second covering part is 0.3mm-0.65mm.

[0019] The third objective of this invention is to provide a battery cell that can improve the sealing between the electrode assembly and the battery casing.

[0020] To achieve this objective, the present invention adopts the following technical solution:

[0021] A battery cell includes a battery casing and the aforementioned electrode assembly structure, with the electrode assembly structure disposed within the battery casing.

[0022] Optionally, the side of the second covering portion opposite to the first covering portion is higher than the top surface of the electrode assembly and lower than the top of the battery case.

[0023] The beneficial effects of this utility model are:

[0024] The insulating film provided by this utility model includes a first covering part and a second covering part. The second covering part surrounds and is fixed to the outer periphery of the first covering part. The second covering part is plastic and thermoplastic. In actual production, the insulating film is laid flat on a plane, the bottom of the electrode assembly is placed on the first covering part, and then the second covering part is stretched and deformed until it covers all the sidewalls of the electrode assembly. Then, the second covering part is heat-treated to shrink and tightly adhere to all the sidewalls of the electrode assembly. It can be seen that the insulating film can cover the bottom surface and all sidewalls of the electrode assembly as a whole. After the electrode assembly is covered, there are no seams on the insulating film, which greatly improves the tightness of the insulating film covering the electrode assembly and provides strong protection for the insulation between the electrode assembly and the battery casing. In addition, after the second covering part shrinks and tightly adheres to the sidewalls of the electrode assembly, the flatness of the second covering part on the sidewalls of the electrode assembly is high, so the process of installing the electrode assembly covered with the insulating film into the battery casing can be relatively smooth. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the insulating film provided by this utility model;

[0026] Figure 2 This is a schematic diagram of the pole assembly provided by this utility model.

[0027] In the picture:

[0028] 11. First covering part; 12. Second covering part; 13. Liquid-permeable structure; 21. Bottom surface; 22. Side wall. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0030] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0031] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0032] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0033] This embodiment provides an insulating film that can be used as a whole to cover the bottom surface and all sidewalls of the electrode assembly, and there are no seams on the insulating film after the electrode assembly is covered.

[0034] Specifically, such as Figure 1 and Figure 2 As shown, the insulating film includes a first covering portion 11 and a second covering portion 12. The first covering portion 11 is used to cover the bottom surface 21 of the electrode assembly, and the second covering portion 12 surrounds and is fixed to the outer periphery of the first covering portion 11. The second covering portion 12 is used to cover all the sidewalls 22 of the electrode assembly, and the second covering portion 12 has plasticity and thermoplasticity.

[0035] In actual production, the insulating film is laid flat on a plane, the bottom of the electrode assembly is placed on the first covering part 11, and then the second covering part 12 is stretched and deformed until it covers all the sidewalls 22 of the electrode assembly. The second covering part 12 is then heat-treated (e.g., hot air is blown onto it) to cause it to shrink and adhere tightly to all the sidewalls 22 of the electrode assembly. Thus, the insulating film can cover the bottom surface 21 and all the sidewalls 22 of the electrode assembly as a whole. After the electrode assembly is covered, there are no seams on the insulating film, significantly improving the tightness of the insulation film covering the electrode assembly. This provides strong protection for the insulation between the electrode assembly and the battery casing, thereby improving the safety of the individual battery cells. Furthermore, after the second covering portion 12 is heat-shrinked and tightly attached to the side wall 22 of the electrode assembly, the second covering portion 12 has a high degree of flatness on the side wall 22 of the electrode assembly, so the process of inserting the electrode assembly covered with the insulating film into the battery case can be relatively smooth.

[0036] It should be noted that in actual production, the second covering part 12 can be stretched and deformed by manually pulling it, or by using mechanical equipment such as a robotic arm to stretch and deform it.

[0037] Furthermore, the second covering part 12 is made of polyvinyl chloride (PVC). PVC material has good plasticity and thermoplasticity. Using PVC material for the second covering part 12 can reduce the probability of the second covering part 12 being damaged when it is pulled. In addition, PVC material has strong corrosion resistance, which can prevent the second covering part 12 from being corroded by electrolyte.

[0038] Optionally, the first covering part 11 is provided with a liquid permeable structure 13, so that the electrolyte can be immersed in the space between the first covering part 11 and the bottom surface 21 of the electrode assembly through the liquid permeable structure 13, so that the electrode assembly can absorb the electrolyte and fully wet the electrode assembly in the electrolyte.

[0039] Furthermore, the liquid-permeable structure 13 is a liquid-permeable slit. In actual production, the liquid-permeable slit can be scribbled or cut on the first covering part 11 using a scriber or cutter, which helps to reduce production difficulty and improve production efficiency. Of course, in other embodiments, the liquid-permeable structure 13 can also be a liquid-permeable hole or a thinning area, etc.

[0040] Furthermore, there are multiple liquid-permeable structures 13, and these multiple liquid-permeable structures 13 are evenly distributed on the first coating part 11 to improve the electrolyte immersion efficiency and ensure that the structural strength of the first coating part 11 is relatively uniform.

[0041] Optionally, when the electrode group's insulating film is stretched, the second covering portion 12 will transfer some of the stretching force to the first covering portion 11. If the plasticity of the first covering portion 11 is greater than or equal to the plasticity of the second covering portion 12, the first covering portion 11 will also deform when the second covering portion 12 is stretched. Furthermore, the liquid-permeable structure 13 provided on the first covering portion 11 will cause uneven stress on the first covering portion 11, which may easily lead to damage to the first covering portion 11. To solve this problem, the plasticity of the first covering portion 11 provided in this embodiment is less than that of the second covering portion 12, thereby reducing the probability of deformation and damage to the first covering portion 11 when the second covering portion 12 is stretched. In actual production, to avoid deformation of the first covering part 11, it is assumed that the first covering part 11 begins to deform when a force F1 is applied to it, and the second covering part 12 begins to deform when a force F2 is applied to it. When the electrode group is covered with insulating film, the tensile force applied to the second covering part 12 is F. Since the plasticity of the first covering part 11 is less than that of the second covering part 12, F1 > F2. Therefore, it is only necessary to make F2 ≤ F < F1 to both deform the second covering part 12 and prevent the first covering part 11 from deforming.

[0042] It should be noted that since the first covering part 11 does not deform when the second covering part 12 is pulled, and the first covering part 11 needs to cover the bottom surface 21 of the electrode assembly, in actual production, the area of ​​the first covering part 11 needs to be equal to the area of ​​the bottom surface 21 of the electrode assembly, and the shape of the first covering part 11 needs to be equal to the shape of the bottom surface 21 of the electrode assembly. For example, in this embodiment, the electrode assembly is a cuboid structure; therefore, both the first covering part 11 and the bottom surface 21 of the electrode assembly are rectangular, and the area of ​​the first covering part 11 is equal to the area of ​​the bottom surface 21 of the electrode assembly. Of course, in other embodiments, the electrode assembly can also be other shapes, such as cylindrical or pentagonal prisms, as long as the area of ​​the first covering part 11 is equal to the area of ​​the bottom surface 21 of the electrode assembly, and the shape of the first covering part 11 is equal to the shape of the bottom surface 21 of the electrode assembly.

[0043] Furthermore, the first covering part 11 is made of polypropylene (PP). PP material has low plasticity (at least lower than PVC material), which can reduce the probability of the first covering part 11 deforming when the second covering part 12 is stretched. In addition, PP material has strong corrosion resistance, which can avoid the problem of the first covering part 11 being corroded by electrolyte.

[0044] Furthermore, the outer periphery of the first covering part 11 is fixedly connected to the second covering part 12 by adhesive bonding. In actual production, there is no need to consider the different melting points of the first covering part 11 and the second covering part 12. Adhesive can be used to bond the first covering part 11 and the second covering part 12 together.

[0045] This embodiment provides an electrode assembly structure, which includes an electrode assembly and the aforementioned insulating film. The bottom surface 21 of the electrode assembly is covered by a first covering portion 11, and all sidewalls 22 of the electrode assembly are covered by a second covering portion 12. The electrode assembly structure uses the aforementioned insulating film, which can significantly improve the tightness of the insulating film covering the electrode assembly, thereby providing a strong guarantee for the insulation between the electrode assembly and the battery casing.

[0046] Optionally, the thickness of the first covering part 11 is greater than the thickness of the second covering part 12. Since the first covering part 11 is pressed at the bottom of the electrode assembly, the force on the first covering part 11 is greater than the force on the second covering part 12. Making the thickness of the first covering part 11 greater than the thickness of the second covering part 12 can increase the structural strength and durability of the first covering part 11 and reduce the probability of the first covering part 11 being damaged and corroded.

[0047] Furthermore, the thickness of the first covering portion 11 is 0.75mm-1.1mm. For example, the thickness of the first covering portion 11 can be 0.75mm, 0.8mm, 0.9mm, 1mm or 1.1mm, etc., wherein the thickness of the first covering portion 11 is preferably 0.8mm-1mm. The thickness of the second covering portion 12 is 0.3mm-0.65mm. For example, the thickness of the second covering portion 12 can be 0.3mm, 0.4mm, 0.5mm, 0.6mm or 0.65mm, etc., wherein the thickness of the second covering portion 12 is preferably 0.4mm-0.6mm. On the basis that both the first covering portion 11 and the second covering portion 12 have a certain structural strength and tolerance, the thickness of the first covering portion 11 and the second covering portion 12 is reduced as much as possible to reduce the volume of the electrode assembly structure or increase the volume of the electrode assembly, thereby achieving the purpose of improving the energy density of the battery cell.

[0048] It should be noted that the thickness of the second covering part 12 is 0.3mm-0.65mm, which refers to the thickness of the second covering part 12 after it covers the side wall 22 of the electrode assembly, that is, the thickness of the second covering part 12 after it is stretched.

[0049] This embodiment provides a battery cell, which includes a battery casing, a cover plate, and the aforementioned electrode assembly structure. The electrode assembly structure is disposed inside the battery casing, and the top of the battery casing has an opening, which is sealed by the cover plate. The battery cell adopts the aforementioned electrode assembly structure, and the sealing between the electrode assembly and the battery casing is relatively high.

[0050] Optionally, the side of the second covering portion 12 facing away from the first covering portion 11 is higher than the top surface of the electrode assembly and lower than the top of the battery case, so that the top surface of the electrode assembly is surrounded by the side of the second covering portion 12 facing away from the first covering portion 11, preventing metal foreign objects in the battery case from contacting the top of the electrode assembly and causing a micro short circuit problem in the electrode assembly. In addition, the side of the second covering portion 12 facing away from the first covering portion 11 is lower than the top of the battery case, which can avoid the problem of interference between the side of the second covering portion 12 facing away from the first covering portion 11 and the cover plate.

[0051] The main production process of the battery cell provided in this embodiment is briefly described below:

[0052] S1. Lay the insulating film flat on the plane, place the electrode assembly with the top cover plate on the insulating film, so that the bottom of the electrode assembly presses on the first covering part 11, use a robotic arm to pull the second covering part 12 to stretch and deform the second covering part 12 until the second covering part 12 covers all the side walls 22 of the electrode assembly, and then perform heat treatment on the second covering part 12 to make the second covering part 12 shrink and adhere tightly to all the side walls 22 of the electrode assembly.

[0053] S2. Process the side of the second covering part 12 that is away from the first covering part 11 so that the side of the second covering part 12 that is away from the first covering part 11 is lower than the cover plate and slightly higher than the top of the electrode assembly.

[0054] S3. Position the bottom surface 21 of the electrode assembly directly opposite the opening in the battery case, and insert the electrode assembly covered with the insulating film into the battery case.

[0055] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. An insulating film, characterized in that, include: The first covering part (11) is used to cover the bottom surface (21) of the electrode assembly; The second covering part (12) surrounds and is fixed to the outer periphery of the first covering part (11). The second covering part (12) is used to cover all the sidewalls (22) of the pole group, and the second covering part (12) is plastic and thermoplastic.

2. The insulating film according to claim 1, characterized in that, The first covering part (11) is provided with a liquid permeable structure (13), and the electrolyte can be immersed in the space between the first covering part (11) and the bottom surface (21) of the electrode assembly through the liquid permeable structure (13).

3. The insulating film according to claim 2, characterized in that, The plasticity of the first covering part (11) is less than that of the second covering part (12).

4. The insulating film according to claim 3, characterized in that, The first covering part (11) is made of PP material.

5. The insulating film according to any one of claims 1-4, characterized in that, The second covering part (12) is made of PVC material.

6. A pole group structure, characterized in that, The electrode assembly includes an electrode group and an insulating film as described in any one of claims 1-5, wherein the bottom surface (21) of the electrode group is covered by the first covering portion (11), and all sidewalls (22) of the electrode group are covered by the second covering portion (12).

7. The pole assembly structure according to claim 6, characterized in that, The thickness of the first covering part (11) is greater than the thickness of the second covering part (12).

8. The pole assembly structure according to claim 6, characterized in that, The thickness of the first covering part (11) is 0.75mm-1.1mm, and the thickness of the second covering part (12) is 0.3mm-0.65mm.

9. A single battery cell, characterized in that, It includes a battery casing and an electrode assembly structure as described in any one of claims 6-8, wherein the electrode assembly structure is disposed within the battery casing.

10. The battery cell according to claim 9, characterized in that, The side of the second covering part (12) opposite to the first covering part (11) is higher than the top surface of the electrode assembly and lower than the top of the battery case.

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