Explosion-proof valve protective film, battery top cover and battery

Abstract

This utility model discloses an explosion-proof valve protective film, a battery top cover, and a battery, belonging to the field of battery technology. It includes a composite film and an adhesive component. The composite film comprises a PET film with symmetrically arranged first and second sides, and a PP film. The PP film is disposed on the first side, and the projection of the PP film onto the first side is located on the first side. The adhesive component is located between the PP film and the first side, and is used to bond the PP film and the PET film. The PP film has a lower elastic modulus than the PET film, and both the PP film and the PET film are sheet-like structures of uniform thickness. The PP film is used to absorb localized stress generated when the composite film is installed on the top cover and to suppress concave deformation of the composite film's sides. This utility model achieves the technical effects of improving durability, reducing the risk of replacing the protective film, and reducing production costs.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, and specifically relates to an explosion-proof valve protective film, a battery top cover, and a battery. Background Technology

[0002] In lithium battery manufacturing, the explosion-proof valve protective film is a crucial component preventing electrolyte contamination and the intrusion of external impurities. In existing technologies, electrolyte easily splashes onto the explosion-proof valve's protective film during the electrolyte injection and formation processes. When the electrolyte remains on the protective film for an extended period, or when the battery is left to stand at high temperatures, it forms indelible marks. These marks not only affect the battery's appearance but also reduce the film's durability, leading to its failure and requiring replacement. Manual replacement of the protective film can easily result in missed areas or accidental puncture of the explosion-proof valve, rendering the battery unusable. This not only increases production costs but also poses a safety threat to operators.

[0003] Therefore, it is necessary to provide a new technical solution to solve the above-mentioned technical problems. Utility Model Content

[0004] The technical problems to be solved by this utility model are poor durability, high risk of replacing the protective film, and high production cost.

[0005] To solve the above-mentioned technical problems, this utility model provides an explosion-proof valve protective film, which includes a composite film and an adhesive. The composite film includes a PET film with a symmetrically arranged first side and a second side, and a PP film. The PP film is disposed on the first side, and the projection of the PP film onto the first side is located on the first side. The adhesive is located between the PP film and the first side, and the adhesive is used to bond the PP film and the PET film. The elastic modulus of the PP film is less than that of the PET film, and the PP film and the PET film are both sheet-like structures of uniform thickness. The PP film is used to absorb local stress generated when the composite film is installed on the top cover and to suppress the concave deformation of the side of the composite film.

[0006] Optionally, the thickness of the PP film is 25% to 50% of the total thickness of the PET film and the PP film.

[0007] Optionally, the adhesive includes an inner ring edge and an outer ring edge, wherein the inner ring edge and the outer ring edge are concentric ellipses to form an elliptical annular region with a uniform width.

[0008] Optionally, the width of the elliptical annular region ranges from 1.73 mm to 1.77 mm.

[0009] Optionally, one end of the inner ring edge is spaced apart from the other end of the inner ring edge; one end of the outer ring edge is spaced apart from the other end of the outer ring edge.

[0010] Optionally, the distance between one end of the inner ring edge and the other end of the inner ring edge ranges from 0.5 mm to 0.7 mm; the distance between one end of the outer ring edge and the other end of the outer ring edge ranges from 0.5 mm to 0.7 mm.

[0011] Optionally, the adhesive is an acrylic adhesive.

[0012] According to another aspect of the present invention, the present invention also provides a battery top cover, the battery top cover including the explosion-proof valve protective film, and further including a top cover piece having a mounting groove and an explosion-proof valve embedded in the mounting groove, the explosion-proof valve protective film covering the explosion-proof valve, and the explosion-proof valve protective film being attached to the outside of the mounting groove.

[0013] Optionally, the PET film is located between the explosion-proof valve and the PP film.

[0014] According to another aspect of the present invention, the present invention also provides a battery, wherein the battery top cover includes the aforementioned battery top cover.

[0015] Beneficial effects:

[0016] This utility model provides an explosion-proof valve protective film, in which a PP film is disposed on the first side of a PET film in a composite film, and the projection of the PP film toward the first side is located on the first side. An adhesive is located between the PP film and the first side and is used to bond the PP film and the PET film. The elastic modulus of the PP film is less than that of the PET film, and the PP film and the PET film are both sheet-like structures of uniform thickness. The PP film is used to absorb the local stress generated when the composite film is installed on the top cover and to suppress the concave deformation of the side of the composite film. The difference in elastic modulus between the PP and PET films creates a stress transfer gradient. When external stress is applied to the composite film, the lower elastic modulus PP film, acting as a stress buffer layer, deforms preferentially. The adhesive ensures the continuity of the stress transfer path, while the uniform sheet structure achieves homogeneity in stress distribution. This effectively disperses stress to the PP film rather than directly onto the PET film. Furthermore, the design where the PP film's projection completely covers the first side of the PET film prevents edge deformation caused by stress concentration deviation. When the protective film is installed on the top cover, it suppresses side concave deformation of the PET film due to stress concentration. Simultaneously, the deformation absorption of the PP film and its structural integrity with the PET film maintain the overall planar stiffness of the composite film, preventing electrolyte penetration into the film layer gaps or the formation of residual marks. The chemical compatibility of the PP film surface with the electrolyte is superior to that of the PET film, and the electrolyte will not form difficult-to-wipe marks on the protective film, thus improving its durability. This achieves the technical effects of improving durability, reducing the risk of replacing the protective film, and lowering production costs. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of an explosion-proof valve protective film provided in an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the composite membrane structure in an explosion-proof valve protective membrane provided for an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the structure of a battery top cover provided in an embodiment of the present utility model. Detailed Implementation

[0021] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0022] To enable those skilled in the art to better understand the solutions of this application, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] In the embodiments of this application, "at least one" refers to one or more; "multiple" refers to two or more. In the description of this application, the terms "first," "second," "third," etc., are used only for the purpose of distinguishing descriptions and should not be construed as indicating or implying relative importance, nor should they be construed as indicating or implying order.

[0024] In this specification, references such as "one embodiment" or "some embodiments" mean that one or more embodiments of this application include the specific features, structures, or characteristics described in connection with that embodiment. Therefore, the terms "comprising," "including," "having," and variations thereof in this specification all mean "including but not limited to," unless otherwise specifically emphasized. It should be noted that in the embodiments of this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0025] It should be noted that, in the embodiments of this utility model, when a component is referred to as being "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. When a component is considered to be "set on" another component, it can be directly set on the other component or there may be an intervening component. Furthermore, in the embodiments of this application, "connection" can also be understood as an electrical connection; the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components. The terms "vertical," "horizontal," "left," "right," and similar expressions used in the embodiments of this utility model are for illustrative purposes only and are not intended to limit the utility model.

[0026] This utility model provides an explosion-proof valve protective film according to Embodiment 1. Please refer to [link / reference]. Figures 1 to 2 As shown, Figure 1 This is a schematic diagram of the structure of a protective membrane for an explosion-proof valve provided in an embodiment of this utility model. Figure 2 This is a schematic diagram of the composite membrane structure in an explosion-proof valve protective film provided by an embodiment of the present invention. The explosion-proof valve protective film provided by this embodiment of the present invention includes a composite membrane 1 and an adhesive member 13. The composite membrane 1 includes a PET film 11 and a PP film 12. The PET film 11 has a first side 111 and a second side 112 symmetrically arranged. The PP film 12 is disposed on the first side 111, and the projection of the PP film 12 toward the first side 111 is located on the first side 111. The adhesive member 13 is located between the PP film 12 and the first side 111. The adhesive member 13 is used to bond the PP film 12 and the PET film 11. The elastic modulus of the PP film 12 is less than that of the PET film 11, and the PP film 12 is a sheet structure of uniform thickness. The PET film 11 is also a sheet structure of uniform thickness. The PP film 12 is used to absorb local stress generated when the composite membrane 1 is installed on the top cover and to suppress the concave deformation of the sides of the composite membrane 1.

[0027] The projection of the PP film 12 onto the XY plane completely covers the first side 111 contact area of ​​the PET film 11, and the four edges of the PP film 12 are aligned with the edges of the PET film 11.

[0028] The difference in elastic modulus between PET film 11 and PP film 12 can form a stepped stress response mechanism, allowing the low-modulus PP film 12 to absorb more initial stress peaks.

[0029] In this embodiment, a PP film 12 is disposed on the first side 111 of a PET film 11 in the composite film 1, and the projection of the PP film 12 toward the first side 111 is located on the first side 111. An adhesive 13 is located between the PP film 12 and the first side 111. The adhesive 13 is used to bond the PP film 12 and the PET film 11. The elastic modulus of the PP film 12 is less than that of the PET film 11, and the PP film 12 is a sheet structure of uniform thickness. The PET film 11 is a sheet structure of uniform thickness. The PP film 12 is used to absorb the local stress generated when the composite film 1 is installed on the top cover and to suppress the concave deformation of the side of the composite film 1. The difference in elastic modulus between the PP film 12 and the PET film 11 creates a stress transfer gradient. When external stress is applied to the composite film 1, the PP film 12, with its lower elastic modulus, acts as a stress buffer layer and deforms preferentially. The adhesive 13 ensures the continuity of the stress transfer path, while the uniform sheet structure achieves homogeneity in stress distribution. This effectively disperses stress to the PP film 12 rather than directly onto the PET film 11. Furthermore, the design of the PP film 12's projection completely covering the first side 111 of the PET film 11 prevents edge deformation caused by stress point deviation. When the protective film is installed on the top cover, it can suppress the side concave deformation of the PET film 11 caused by stress concentration. Simultaneously, through the deformation absorption of the PP film 12 and the structural maintenance with the PET film 11, the composite film 1 maintains overall planar stiffness, preventing electrolyte from penetrating into the gaps between film layers or forming residual marks. The chemical compatibility between the PP film 12 surface and the electrolyte is superior to that of the PET film 11, and the electrolyte will not form hard-to-wipe marks on the protective film, thus improving the durability of the protective film. This achieves the technical effects of improving durability, reducing the risk of replacing the protective film, and lowering production costs.

[0030] In one embodiment, the thickness of the PP film 12 is 25% to 50% of the total thickness of the PET film 11 and the PP film 12. The total thickness of the PET film 11 and the PP film 12 refers to... Figure 2 The total thickness of the PET film 11 and PP film 12 along the vertical direction is shown. The thickness of the PP film 12 is 25% to 50% of the total thickness of the PET film 11 and PP film 12. The low elastic modulus of the PP film 12 can act as a stress buffer layer to preferentially deform, while maintaining the planar stiffness of the composite film 1 through the remaining thickness. This is beneficial to optimizing the stress absorption capacity of the PP film 12 and the rigid support of the PET film 11, so that the external stress is effectively dispersed to the PP film 12, and the PET film 11 is prevented from undergoing concave deformation due to stress concentration on the side.

[0031] In some embodiments, the adhesive 13 includes an inner ring edge 131 and an outer ring edge 132, which are concentric ellipses to form an elliptical annular region with a uniform width. The inner ring edge 131 and the outer ring edge 132 refer to the edges on opposite sides of the adhesive 13, and the inner ring edge 131 and the outer ring edge 132 can enclose the area where the adhesive 13 is located. The inner ring edge 131 and the outer ring edge 132 of the adhesive 13 are concentric ellipses, which can form an elliptical annular region with a uniform width. The concentric elliptical structure makes the bonding area of ​​the adhesive 13 between the PET film 11 and the PP film 12 uniformly distributed, avoiding local concentration or lack of adhesive force. At the same time, the uniform annular width makes the stress transmission path continuous and uniformly distributed when passing through the adhesive 13, preventing the stress from forming abrupt gradients at the edge of the composite film 1.

[0032] In some embodiments, the width of the elliptical annular region ranges from 1.73 mm to 1.77 mm. The width of the elliptical annular region refers to the distance between the inner ring edge 131 and the outer ring edge 132 in the adhesive member 13. A width range of 1.73 mm to 1.77 mm balances the bonding area and edge structural strength, ensuring that the adhesive member 13 guarantees the interlayer bonding strength of the composite film 1 without restricting the deformation freedom of the PP film 12 due to an excessively wide bonding area. If the width of the elliptical annular region is less than 1.73 mm, insufficient bonding area may lead to delamination risk; if the width of the elliptical annular region is greater than 1.77 mm, the edge area of ​​the elliptical annular region becomes too rigid, hindering the deformation buffering effect of the PP film 12.

[0033] In some embodiments, one end of the inner ring edge 131 is spaced apart from the other end, and one end of the outer ring edge 132 is spaced apart from the other end. The spaced-apart annular edges allow the adhesive 13 to undergo minor deformation in the spaced areas when the composite film 1 is subjected to external stress, forming localized stress relief zones. This helps prevent stress from continuously accumulating along the annular closed path, thereby reducing the risk of deformation on the sides of the PET film 11 due to circumferential stress concentration.

[0034] In some embodiments, the distance between one end of the inner ring edge 131 and the other end of the inner ring edge 131 ranges from 0.5 mm to 0.7 mm, and the distance between one end of the outer ring edge 132 and the other end of the outer ring edge 132 ranges from 0.5 mm to 0.7 mm. The distance between one end of the inner ring edge 131 and the other end of the inner ring edge 131 refers to the distance between the two ends of the inner ring edge 131. When the distance is less than 0.5 mm, the deformation buffer space is insufficient. When the distance is greater than 0.7 mm, the edge may warp due to the excessive length of the adhesive area break. Therefore, the distance between one end of the inner ring edge 131 and the other end of the inner ring edge 131 should be between 0.5 mm and 0.7 mm, and the distance between one end of the outer ring edge 132 and the other end of the outer ring edge 132 should also be between 0.5 mm and 0.7 mm. The spacing area can provide sufficient deformation buffer space to absorb local stress and maintain the integrity of the edge structure of the adhesive part 13.

[0035] In some embodiments, the adhesive 13 is an acrylic adhesive, which has high bonding strength and resistance to electrolyte corrosion. The polar groups in the molecular chain of the acrylic adhesive form stable chemical bonds with the surfaces of the PET film 11 and the PP film 12. When the composite film 1 is installed onto the top cover, the acrylic adhesive bonds the PP film 12 and the PET film 11 interface through uniform adhesive force, which can avoid the interruption of stress transmission path due to local delamination. At the same time, the low hygroscopicity of the acrylic adhesive can also reduce the risk of electrolyte penetration into the gaps between the adhesive layers.

[0036] To provide a detailed description of the battery top cover 2 provided by this utility model, the above embodiment 1 provides a detailed description of an explosion-proof valve protective film. Based on the same utility model concept, this application also provides a battery top cover 2, as detailed in embodiment 2.

[0037] Please see Figure 3 As shown, Figure 3This is a schematic diagram of a battery top cover provided in an embodiment of the present invention. Embodiment two of the present invention provides a battery top cover 2, including a top cover piece 21 and an explosion-proof valve. The top cover piece 21 has a mounting groove 211, the explosion-proof valve is embedded inside the mounting groove 211, a protective film covers the explosion-proof valve, and the protective film is affixed to the outside of the mounting groove 211. Those skilled in the art will understand that the specific structure of the explosion-proof valve in the battery top cover 2 provided in Embodiment two of the present invention is not limited. It is only necessary that when the internal pressure of the battery rises sharply above a safety threshold, the explosion-proof valve can quickly open through mechanical deformation or rupture to release internal gas and pressure, preventing the battery casing from bursting due to overpressure. The PET film 11 is located between the explosion-proof valve and the PP film 12. By affixing the protective film to the outside of the mounting groove 211, direct contact between the protective film and the operating area of ​​the explosion-proof valve can be avoided, thus eliminating the dynamic shear force on the protective film when the explosion-proof valve opens and closes. The PP film 12 layer of the protective film preferentially absorbs the local stress during top cover assembly, and the PET film 11 layer can also maintain the overall planar rigidity. Meanwhile, the PP film 12, as the outer layer, is directly exposed to the electrolyte environment. It can take advantage of the chemical compatibility between the PP film 12 and the electrolyte to avoid the formation of residues after the electrolyte comes into contact with the PET film 11. The PET film 11, as the intermediate layer, supports the rebound of the PP film 12 after deformation through the high elastic modulus of the PET film 11, thus maintaining the overall flatness of the composite film 1.

[0038] This utility model provides a battery top cover 2, in which a PP film 12 is disposed on a first side 111 of a PET film 11 in a composite film 1, and the projection of the PP film 12 toward the first side 111 is located on the first side 111. An adhesive 13 is located between the PP film 12 and the first side 111. The adhesive 13 is used to bond the PP film 12 and the PET film 11. The elastic modulus of the PP film 12 is less than that of the PET film 11, and the PP film 12 is a sheet structure of uniform thickness. The PET film 11 is a sheet structure of uniform thickness. The PP film 12 is used to absorb the local stress generated when the composite film 1 is installed on the top cover and to suppress the concave deformation of the side of the composite film 1. The difference in elastic modulus between the PP film 12 and the PET film 11 creates a stress transfer gradient. When external stress is applied to the composite film 1, the PP film 12, with its lower elastic modulus, acts as a stress buffer layer and deforms preferentially. The adhesive 13 ensures the continuity of the stress transfer path, while the uniform sheet structure achieves homogeneity in stress distribution. This effectively disperses stress to the PP film 12 rather than directly onto the PET film 11. Furthermore, the design of the PP film 12's projection completely covering the first side 111 of the PET film 11 prevents edge deformation caused by stress point deviation. When the protective film is installed on the top cover, it can suppress the side concave deformation of the PET film 11 caused by stress concentration. Simultaneously, through the deformation absorption of the PP film 12 and the structural maintenance with the PET film 11, the composite film 1 maintains overall planar stiffness, preventing electrolyte from penetrating into the gaps between film layers or forming residual marks. The chemical compatibility between the PP film 12 surface and the electrolyte is superior to that of the PET film 11, and the electrolyte will not form hard-to-wipe marks on the protective film, thus improving the durability of the protective film. This achieves the technical effects of improving durability, reducing the risk of replacing the protective film, and lowering production costs.

[0039] To provide a detailed description of the battery provided by this utility model, the above embodiment 1 provides a detailed description of an explosion-proof valve protective film. Based on the same utility model concept, this application also provides a battery, as detailed in embodiment 3.

[0040] This utility model embodiment three provides a battery, the battery top cover 2 including the aforementioned battery top cover 2. The battery top cover 2 protects the explosion-proof valve by covering it with an explosion-proof valve protective film. When the internal pressure of the battery is abnormal, the protective film can still maintain the interface integrity during the operation of the explosion-proof valve. The stress absorption capacity of the PP film 12 will prevent the stress of the top cover assembly from being transmitted to the internal structure of the battery, and the rigid support of the PET film 11 will prevent the protective film from swelling and deforming due to electrolyte immersion.

[0041] This utility model provides a battery in which a PP film 12 is disposed on a first side 111 of a PET film 11 in a composite film 1, and the projection of the PP film 12 toward the first side 111 is located on the first side 111. An adhesive 13 is located between the PP film 12 and the first side 111. The adhesive 13 is used to bond the PP film 12 and the PET film 11. The elastic modulus of the PP film 12 is less than that of the PET film 11, and the PP film 12 is a sheet structure of uniform thickness. The PET film 11 is a sheet structure of uniform thickness. The PP film 12 is used to absorb the local stress generated when the composite film 1 is installed on the top cover and to suppress the concave deformation of the side of the composite film 1. The difference in elastic modulus between the PP film 12 and the PET film 11 creates a stress transfer gradient. When external stress is applied to the composite film 1, the PP film 12, with its lower elastic modulus, acts as a stress buffer layer and deforms preferentially. The adhesive 13 ensures the continuity of the stress transfer path, while the uniform sheet structure achieves homogeneity in stress distribution. This effectively disperses stress to the PP film 12 rather than directly onto the PET film 11. Furthermore, the design of the PP film 12's projection completely covering the first side 111 of the PET film 11 prevents edge deformation caused by stress point deviation. When the protective film is installed on the top cover, it can suppress the side concave deformation of the PET film 11 caused by stress concentration. Simultaneously, through the deformation absorption of the PP film 12 and the structural maintenance with the PET film 11, the composite film 1 maintains overall planar stiffness, preventing electrolyte from penetrating into the gaps between film layers or forming residual marks. The chemical compatibility between the PP film 12 surface and the electrolyte is superior to that of the PET film 11, and the electrolyte will not form hard-to-wipe marks on the protective film, thus improving the durability of the protective film. This achieves the technical effects of improving durability, reducing the risk of replacing the protective film, and lowering production costs.

[0042] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although this utility model has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the claims of this utility model.

Claims

1. An explosion valve protection membrane, characterized in that The explosion-proof valve protective film includes a composite film and an adhesive. The composite film includes a PET film having a first side and a second side symmetrically arranged, and a PP film. The PP film is disposed on the first side, and the projection of the PP film onto the first side is located on the first side. The adhesive is located between the PP film and the first side surface, and the adhesive is used to bond the PP film and the PET film. The PP film has a lower elastic modulus than the PET film, and the PP film is a sheet structure of uniform thickness, as is the PET film. The PP film is used to absorb local stress generated when the composite film is installed on the top cover and to suppress the side concave deformation of the composite film.

2. The burst valve protection membrane of claim 1, wherein, The thickness of the PP film is 25% to 50% of the total thickness of the PET film and the PP film.

3. The burst valve protection membrane of claim 1, wherein, The adhesive includes an inner ring edge and an outer ring edge, wherein the inner ring edge and the outer ring edge are concentric ellipses to form an elliptical annular region with a uniform width.

4. The burst valve protection membrane of claim 3, wherein, The width of the elliptical annular region ranges from 1.73 mm to 1.77 mm.

5. The burst valve protection membrane of claim 3, wherein, One end of the inner ring edge is spaced apart from the other end of the inner ring edge; one end of the outer ring edge is spaced apart from the other end of the outer ring edge.

6. The burst valve protection membrane of claim 5, wherein, The distance between one end of the inner ring edge and the other end of the inner ring edge ranges from 0.5 mm to 0.7 mm; the distance between one end of the outer ring edge and the other end of the outer ring edge ranges from 0.5 mm to 0.7 mm.

7. The burst valve protection membrane of claim 1, wherein, The adhesive is an acrylic adhesive.

8. A battery top cover characterized by, The battery top cover includes an explosion-proof valve protective film as described in any one of claims 1 to 7, and also includes a top cover plate with a mounting groove and an explosion-proof valve embedded in the mounting groove, wherein the explosion-proof valve protective film covers the explosion-proof valve and is attached to the outside of the mounting groove.

9. The battery top cover according to claim 8, characterized in that, The PET film is located between the explosion-proof valve and the PP film.

10. A battery, characterized in that, The battery top cover includes the battery top cover as described in claim 8.

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