Protective film, cover plate assembly and battery

Abstract

A protective film (100), a cover plate assembly and a battery. The protective film (100) comprises: a first film layer (1), which is provided with a mounting surface (1A), the mounting surface (1A) being located on one side of the first film layer (1); an adhesive layer (2), which is attached to the mounting surface (1A), the adhesive layer (2) comprising a first area (21) and a second area (22) arranged around the first area (21); and a second film layer (3), which is provided on the side of the adhesive layer (2) facing away from the first film layer (1) and is located in the first area (21), wherein the second area (22) of the adhesive layer (2) is configured to be connected to a top cover (7) of a battery.

Description

Protective film, cover plate assembly and battery

[0001] The present application claims priority to the Chinese patent application No. 202421134766.4 filed on May 22, 2024 with the China Patent Office, the whole content of the above application is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of battery, in particular to a protective film, a cover plate assembly and a battery. BACKGROUND

[0003] In the related art, in order to prevent sharp objects from damaging the explosion-proof valve or foreign matter and dust from falling into the explosion-proof valve, a protective film for the explosion-proof valve is needed to be arranged on the upper surface of the explosion-proof valve; generally, the protective film for the explosion-proof valve is adhered to the top cover of the battery by glue, and the commonly used way is to coat the whole surface of the adhesive surface of the protective film for the explosion-proof valve with glue or to coat the adhesive surface of the protective film for the explosion-proof valve with annular glue. SUMMARY

[0004] In the way of coating the whole surface of the adhesive surface of the protective film for the explosion-proof valve with glue, the protective film for the explosion-proof valve may be sucked back to be adhered to the explosion-proof valve under thermal expansion and contraction and negative pressure, so that the protective film for the explosion-proof valve is uneven and easy to fall off; in the way of coating the adhesive surface of the protective film for the explosion-proof valve with annular glue, the adhesive surface of the protective film for the explosion-proof valve is coated with glue, and then part of the glue is removed to form annular glue, so that the process of adhering the protective film for the explosion-proof valve is increased, and compared with the way of coating the whole surface of the adhesive surface of the protective film for the explosion-proof valve with glue, the way of coating the adhesive surface of the protective film for the explosion-proof valve with annular glue also has higher requirements for the precision of the equipment, thereby increasing the cost.

[0005] In one aspect, the present application provides a protective film, comprising:

[0006] A first film layer is provided with a mounting surface, and the mounting surface is located on one side of the first film layer;

[0007] A glue layer is attached to the mounting surface, and the glue layer comprises a first region and a second region arranged around the first region; and

[0008] A second film layer is arranged on the side of the glue layer away from the first film layer and located in the first region;

[0009] The second region of the glue layer is configured to be connected with the top cover of the battery.

[0010] In a second aspect, the present application provides a cover plate assembly, comprising:

[0011] A top cover is provided with a mounting hole;

[0012] An explosion-proof valve is arranged in the mounting hole; and

[0013] The protective film comprises the first film layer, the adhesive layer and the second film layer, the second film layer covers the first area of the adhesive layer.

[0014] In a third aspect, the application provides a battery comprising the cover plate assembly of the second aspect. Advantages

[0015] The protective film, the cover plate assembly and the battery provided by the application have the following advantages: the first film layer, the adhesive layer and the second film layer are stacked in sequence to form the protective film, and the second film layer covers the first area of the adhesive layer. Since the second film layer is located between the adhesive layer and the explosion-proof valve, when the protective film is in thermal expansion and contraction and negative pressure and is sucked back, the adhesive layer can be prevented from directly contacting the explosion-proof valve and the protective film from being bonded to the explosion-proof valve. In addition, since the adhesive layer is full-area and not annular, compared with the annular adhesive layer used in the related art, the technical solution of the application eliminates the process step of removing part of the adhesive layer on the explosion-proof valve, that is, part of the adhesive layer in the first area does not need to be removed, thereby reducing the process before the protective film is bonded to the top cover of the battery and reducing the production cost of the protective film. BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is a perspective view of the protective film according to an implementation of the application;

[0017] FIG. 2 is a perspective view and a partial enlarged view of the protective film according to an implementation of the application;

[0018] FIG. 3 is a structural schematic view and a partial enlarged view of the protective film according to an implementation of the application;

[0019] FIG. 4 is a structural schematic view of the adhesive layer according to an implementation of the application;

[0020] FIG. 5 is a structural schematic view of the first film layer according to an implementation of the application;

[0021] FIG. 6 is an enlarged view of A in FIG. 5;

[0022] FIG. 7 is an exploded schematic view of the cover plate assembly according to an implementation of the application.

[0023] REFERENCE SIGNS

[0024] 100, protective film; 1, first film layer; 1A, mounting surface; 2, adhesive layer; 21, first area; 211, first sub-area; 212, second sub-area; 22, second area; 3, second film layer; 4, boundary line; 5, edge line; 6, air hole; 61, hole segment; 7, top cover; 8, mounting hole; 9, explosion-proof valve. IMPLEMENTATION OF THE INVENTION

[0025] In the present application, the orientation words such as "upper" and "lower" generally refer to the upper and lower positions of the device in the actual use or working state, and specifically refer to the orientation of the drawing surface in the drawings, unless otherwise specified. The "inner" and "outer" refer to the profile of the device.

[0026] The present application provides a protective film, and Figs. 1 to 6 are some embodiments of the present application.

[0027] Please refer to Figs. 1 to 3, in some embodiments of the present application, the protective film 100 comprises a first film layer 1, the first film layer 1 is provided with a mounting surface 1A, the mounting surface 1A is located on one side of the first film layer 1; wherein the mounting surface 1A faces the top cover 7 of the battery.

[0028] In some embodiments of the present application, the protective film 100 further comprises a glue layer 2, the glue layer 2 is attached to the mounting surface 1A; wherein the glue layer 2 can cover the entire surface of the mounting surface 1A, or can cover part of the mounting surface 1A, which is not limited herein; in a specific embodiment of the present application, the glue layer 2 is arranged on the entire surface of the mounting surface 1A, and when the corresponding gluing operation is performed on the first film layer 1 by manual or equipment, it is not necessary to control the gluing range, so that the glue layer 2 can be coated on the entire surface of the mounting surface 1A, and compared with the gluing method using the annular glue layer in the related art, part of the glue removal process is saved. Similarly, the glue layer 2 arranged on the entire surface of the mounting surface 1A can also enable the first film layer 1 and the glue layer 2 to be produced by die cutting, and after die cutting, the combined structure of the first film layer 1 and the glue layer 2 according to the embodiments of the present application is directly formed.

[0029] The glue layer 2 comprises a first area 21 and a second area 22 arranged around the first area 21, the second film layer 3 is arranged on the side of the glue layer 2 away from the first film layer 1 and located in the first area 21; that is, the glue layer 2 located in the first area 21 can bond the first film layer 1 and the second film layer 3 to form the protective film 100; the glue layer 2 located in the second area 22 is in an exposed state, configured to be bonded with the top cover 7 of the battery, to realize the connection between the protective film 100 and the top cover 7 of the battery, and thus the protective film 100 can protect the explosion-proof valve 9 in the top cover 7.

[0030] In the technical solution of the present application, the first film layer 1, the glue layer 2 and the second film layer 3 are sequentially stacked to form the protective film 100, and the second film layer 3 covers the first area 21 of the glue layer 2. Since the second film layer 3 is located between the glue layer 2 and the explosion-proof valve 9, when the protective film 100 is in thermal expansion and contraction and negative pressure and is sucked back, the direct contact between the glue layer 2 and the explosion-proof valve 9 can be reduced, and the situation that the protective film 100 is bonded to the explosion-proof valve 9 can be avoided. Similarly, since the glue layer 2 is an integral surface and not annular, compared with the annular gluing method for the explosion-proof valve film in the related art, the technical solution of the embodiment of the present application eliminates the process step of removing part of the glue on the explosion-proof valve film, that is, part of the glue layer 2 located in the first area 21 does not need to be removed, thereby reducing the process before the protective film 100 is pasted to the top cover 7 of the battery, and reducing the production cost of the protective film 100.

[0031] In addition, since the protective film 100 of the embodiment of the present application adopts a multi-layer film superposition form, that is, the first film layer 1 and the second film layer 3 are stacked together by the glue layer 2 to form a double-layer film structure, the thickness of the double-layer film structure is increased compared with the single-layer film, so that the hardness of the existing double-layer film structure is increased, and the anti-deformation ability is stronger, and compared with the explosion-proof valve film in the related art, the deformation problem is less likely to occur, and the initial shape can be effectively maintained under the condition of thermal expansion and contraction and negative pressure.

[0032] It can be understood that, in order to ensure the protection effect of the protective film 100 on the explosion-proof valve 9, the protective film 100 has a certain tensile strength and flexibility; in an embodiment of the present application, the material of the first film layer 1 is one of polyethylene glycol terephthalate (PET), polyethylene (PE) and polyimide (PI); in another embodiment of the present application, the material of the second film layer 3 is one of polyethylene glycol terephthalate (PET), polyethylene (PE) and polyimide (PI).

[0033] In order to ensure the tensile strength and flexibility of the protective film 100, at least one of the two embodiments is provided. That is, in a specific embodiment of the present application, the material of the first film layer 1 and the second film layer 3 is one of polyethylene glycol terephthalate (PET), polyethylene (PE) and polyimide (PI).

[0034] In this embodiment, since the first film layer 1 is bonded to the top cover 7 of the battery via the adhesive layer 2, the thickness of the adhesive layer 2, together with the thickness of the first film layer 1, increases the overall thickness of the protective film 100. Simultaneously, it allows the protective film 100 to adhere more firmly to the top cover 7 of the battery. In some embodiments of this application, the thickness of the protective film 100 in the first direction is H, and the thickness of the first film layer 1 in the first direction is H1. H and H1 satisfy: 1 / 3H ≤ H1 ≤ 2 / 3H. That is, setting the thickness H1 of the first film layer 1 to satisfy this range satisfies the adhesion strength requirements of the protective film 100. If the value of H1 is less than 1 / 3H, the thickness of the first film layer 1 is too thin, which may result in low adhesion strength of the protective film 100. If the value of H1 is greater than 2 / 3H, the thickness of the first film layer 1 is too thick, thereby increasing the production cost of the protective film 100.

[0035] It should be noted that the first direction is the X direction in Figure 3, which is the stacking direction of the first film layer 1, the adhesive layer 2 and the second film layer 3. The following text will describe the first direction X.

[0036] In some embodiments of this application, the thickness of the adhesive layer 2 in the first direction X is H2; wherein H and H2 satisfy: 1 / 3H ≤ H2 ≤ 2 / 3H. The thickness H2 of the adhesive layer 2 is set to meet this range because the adhesive layer 2 mainly functions as an adhesive. This setting ensures that the adhesive layer 2 meets the bonding strength requirements of the protective film 100, while also preventing the adhesive layer 2 from being too thick and affecting the tensile strength and flexibility of the protective film 100. If the value of H2 is less than 1 / 3H, the thickness of the adhesive layer 2 is too thin, which will affect the bonding effect between the first film layer 1 and the second film layer 3, and between the first film layer 1 and the top cover 7 of the battery. If the value of H2 is greater than 2 / 3H, the thickness of the adhesive layer 2 is too thick, which not only affects the tensile strength and flexibility of the protective film 100, but also increases the manufacturing cost of the adhesive layer 2.

[0037] In some embodiments of the present application, H also satisfies: 0.05mm≤H≤3mm. That is, setting H to satisfy this interval range can make the protective film 100 have excellent adhesion effect, while also effectively reducing the material cost of the protective film 100. If the value of H is less than 0.05mm, there may be a problem that the thickness of the protective film 100 is too thin to cause poor adhesion effect; if the value of H is greater than 3mm, the material cost of the protective film 100 is increased. The value of H can be 0.05mm, 0.10mm, 0.20mm, 0.30mm, 0.40mm, 0.50mm, 0.60mm, 0.70mm, 0.80mm, 0.90mm, 1.00mm, 1.10mm, 1.20mm, 1.30mm, 1.40mm, 1.42mm, 1.45mm, 1.47mm, 1.50mm, 1.60mm, 1.70mm, 1.80mm, 1.90mm, 2.00mm, 2.10mm, 2.20mm, 2.30mm, 2.40mm, 2.50mm, 2.60mm, 2.70mm, 2.80mm, 2.90mm, 3.00mm. The value of H is not limited to the listed values, and other values not listed in this range are also applicable.

[0038] Referring to FIGS. 3 and 4, in some embodiments of the present application, the vertical distance between the boundary line 4 between the first region 21 and the second region 22 of the adhesive layer 2 and the edge line 5 of the second region 22 of the adhesive layer 2 is L; wherein L satisfies: 0.1mm≤L≤6mm. It can be understood that the value of L determines the size of the second region 22, and setting L to satisfy this interval range can improve the tolerance range of the protective film 100 when pasted, while also improving the adhesion of the protective film 100.

[0039] If the value of L is less than 0.1mm, the size of the adhesive layer 2 in the second region 22 is too small. Since the adhesive layer 2 in the second region 22 is bonded with the top cover 7 of the battery, this makes the protective film 100 have higher accuracy requirements for positioning equipment when pasted to the window position of the explosion-proof valve 9, and the tolerance range of the paste is smaller, while the contact area between the adhesive layer 2 in the second region 22 and the top cover 7 is smaller, resulting in poor adhesion of the protective film 100; if the value of L is greater than 6mm, the size of the adhesive layer 2 in the second region 22 is too large, which not only slightly improves the deformation resistance of the protective film 100 under vacuum baking and negative pressure state, but also increases the material cost of the protective film 100.

[0040] The value of L can be 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4 mm, 4.2 mm, 4.4 mm, 4.6 mm, 4.8 mm, 5 mm, 5.2 mm, 5.4 mm, 5.6 mm, 5.8 mm, 6 mm. The value of L is not limited to the listed values, and other values in the range are also applicable.

[0041] In addition, the vertical distance from the boundary line 4 of the first area 21 and the second area 22 to the edge line 5 of the second area 22 can be the same or different, which is not limited here, as long as the value of L meets the above-mentioned range. It should be noted that, referring to FIG. 4, the boundary line 4 is the dashed line part indicated by the arrow 4 in FIG. 4.

[0042] Referring to FIG. 5, the protective film 100 is provided with at least one air hole 6; the air hole 6 is located in the first area 21 and penetrates the protective film 100 from the first film layer 1 to the second film layer 3. The air hole 6 is provided to ensure that the space formed between the explosion-proof valve 9, the protective film 100 and the top cover 7 is in communication with the external environment, and the space formed between the explosion-proof valve 9, the protective film 100 and the top cover 7 has no pressure difference with the outside, so as to avoid the problem of uneven protective film 100 caused by back suction of the protective film 100 under the conditions of thermal expansion and cold contraction and negative pressure, thereby affecting the appearance of the battery. It can be understood that the number of air holes 6 is not limited, which can be one or more. Similarly, the shape of the air hole 6 is not limited, which can be round, polygonal or special-shaped structure.

[0043] In some embodiments of the present application, the air hole 6 includes at least one hole section 61, and the hole section 61 is arranged in a strip shape. That is, the air hole 6 can be composed of one hole section 61, or composed of a plurality of hole sections 61 combined together; and the shape of the air hole 6 can be a straight line type, an L type, a cross type, etc., which is not limited here.

[0044] Please refer to FIG. 6, in some embodiments of the present application, the hole width of hole section 61 is W; wherein W satisfies: 0.05mm≤W≤0.5mm. That is, the value of W satisfies this interval range, which can meet the air permeability requirement of protective film 100 and avoid dust and foreign matter entering the space formed between explosion-proof valve 9, protective film 100 and top cover 7; if the value of W is less than 0.05mm, air permeable hole 6 cannot meet the air permeability requirement of protective film 100; if the value of W is greater than 0.5mm, the size of air permeable hole 6 is too large, which cannot achieve better protection effect on dust and foreign matter. The value of W can be 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm. The value of W is not limited to the listed values, and other values not listed in this range are also applicable.

[0045] In some embodiments of the present application, the length of hole section in its extension direction is L1; wherein L1 satisfies: 1.5mm≤L1≤3mm. That is, setting the value of L1 to satisfy this interval range can meet the air permeability requirement of protective film 100 and avoid dust and foreign matter entering the space formed between explosion-proof valve 9, protective film 100 and top cover 7; if L1 is greater than 3mm, the size of air permeable hole 6 is too large, which cannot achieve better protection effect on dust and foreign matter, and at the same time, it may also affect the tensile strength and flexibility of protective film 100 due to the too large size of air permeable hole 6; if the value of L1 is less than 1.5mm, air permeable hole 6 cannot meet the air permeability requirement of protective film 100. The value of L1 can be 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.22mm, 2.24mm, 2.26mm, 2.28mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm. The value of L1 is not limited to the listed values, and other values not listed in this range are also applicable.

[0046] In some embodiments of the present application, the number of hole sections 61 is multiple, and multiple hole sections 61 are intersected and communicated with each other. That is, in this embodiment, two hole sections 61 can be intersected to form air permeable hole 6, three hole sections 61 can be intersected to form air permeable hole 6, or more than three hole sections 61 can be intersected to form air permeable hole 6, which is not limited herein.

[0047] In a specific embodiment of the present application, the number of hole segments 61 is two, and the two hole segments 61 are arranged in a cross shape; that is, the air vent hole 6 is a cross hole, and the length of the two hole segments 61 in the respective extension directions is the length and width of the air vent hole 6; on the basis that the W value and the L1 value of the hole segment 61 are limited, the length and width of the cross hole are both between 1.5 mm and 3 mm.

[0048] In addition, the position of the air vent hole 6 is not limited and can be at any position on the protective film 100, as long as the space formed between the explosion-proof valve 9, the protective film 100, and the top cover 7 is in communication with the external environment. In some embodiments of the present application, the first region 21 includes a first sub-region 211 and a second sub-region 212 arranged around the first sub-region 211, and the second sub-region 212 is located between the first sub-region 211 and the second region 22; wherein the air vent hole 6 is located in the first sub-region 211. The second region 22 is the edge region of the protective film 100, and such an arrangement avoids the air vent hole 6 being located close to the second region 22, so that the adhesion between the first film layer 1 and the top cover 7 of the battery is not affected when the protective film 100 is inverted, and the aesthetic level of the protective film 100 is also improved.

[0049] It should be noted that, referring to FIG. 4, the dashed line between the first sub-region 211 and the second sub-region 212 is the boundary between the first sub-region 211 and the second sub-region 212.

[0050] Referring to FIG. 7, the present application also provides a cover plate assembly, which includes a top cover 7, an explosion-proof valve 9, and a protective film 100. The top cover 7 is provided with a mounting hole 8, and the explosion-proof valve 9 is arranged in the mounting hole 8. The protective film 100 is as described above, and the protective film 100 is arranged on the mounting hole 8, and the second region 22 of the adhesive layer 2 is connected to the top cover 7. Since the cover plate assembly adopts all the technical solutions of the above-mentioned embodiments, it at least has the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here.

[0051] The protective film 100 is arranged on the mounting hole 8 to protect the explosion-proof valve 9 located in the mounting hole 8.

[0052] The present application also provides a battery, which includes a cover plate assembly as described above. Since the battery adopts all the technical solutions of the above-mentioned embodiments, it at least has the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here.

Claims

1. A protective film (100), comprising: a first film layer (1) provided with a mounting surface (1A) on one side of the first film layer (1); an adhesive layer (2) attached to the mounting surface (1A), the adhesive layer (2) comprising a first region (21) and a second region (22) disposed around the first region (21); and a second film layer (3) disposed on the side of the adhesive layer (2) away from the first film layer (1) and located within the first region (21); wherein the second region (22) of the adhesive layer (2) is configured to be connected to a top cover (7) of a battery.

2. The protective film (100) according to claim 1, wherein The first film layer (1), the adhesive layer (2), and the second film layer (3) are stacked in a first direction, the thickness of the protective film (100) in the first direction is H, and the thickness of the first film layer (1) in the first direction is H1; wherein the H and the H1 satisfy: 1 / 3H≤H1≤2 / 3H.

3. The protective film (100) according to claim 1, wherein The first film layer (1), the adhesive layer (2), and the second film layer (3) are stacked in a first direction, the thickness of the protective film (100) in the first direction is H, and the thickness of the adhesive layer (2) in the first direction is H2; wherein the H and the H2 satisfy: 1 / 3H≤H2≤2 / 3H.

4. The protective film (100) according to claim 2 or 3, wherein The H also satisfies: 0.05mm≤H≤3mm.

5. The protective film (100) according to any one of claims 1 to 3, wherein The vertical distance between the boundary line (4) between the first region (21) and the second region (22) of the adhesive layer (2) and the edge line (5) of the second region (22) of the adhesive layer (2) is L; wherein the L satisfies: 0.1mm≤L≤6mm.

6. The protective film (100) according to any one of claims 1 to 3, wherein The protective film (100) is provided with at least one air hole (6), the air hole (6) is located within the first region (21) and penetrates the protective film (100) from the first film layer (1) to the second film layer (3).

7. The protective film (100) according to claim 6, wherein The air hole (6) comprises at least one hole section (61), and the hole section (61) is arranged in a strip shape.

8. The protective film (100) according to claim 7, wherein The hole width of the hole section (61) is W, and the length of the hole section (61) in its extension direction is L1; wherein the W and the L1 satisfy: 0.05mm≤W≤0.5mm; and 1.5mm≤L1≤3mm.

9. The protective film (100) according to claim 7, wherein The number of hole sections (61) is multiple, and multiple hole sections (61) are intersected and communicated with each other.

10. The protective film (100) according to claim 7, wherein The number of hole sections (61) is two, and the two hole sections (61) are arranged in a cross shape.

11. The protective film (100) according to claim 6, wherein The first region (21) comprises a first sub-region (211) and a second sub-region (212) disposed around the first sub-region (211), and the second sub-region (212) is located between the first sub-region (211) and the second region (22); wherein the air hole (6) is located within the first sub-region (211).

12. The protective film (100) according to any one of claims 1 to 3, wherein The material of the first film layer (1) is one of polyethylene terephthalate, polyethylene, and polyimide.

13. The protective film (100) according to any one of claims 1 to 3, wherein The material of the second film layer (3) is one of polyethylene terephthalate, polyethylene and polyimide.

14. The protective film (100) according to any one of claims 1 to 3, wherein The material of the first film layer (1) is one of polyethylene terephthalate, polyethylene and polyimide, and the material of the second film layer (3) is one of polyethylene terephthalate, polyethylene and polyimide.

15. A cover plate assembly comprising: a top cover (7) provided with a mounting hole (8); an explosion-proof valve (9) arranged in the mounting hole (8); and a protective film (100) comprising the protective film (100) according to any one of claims 1 to 12, the protective film (100) being arranged on the mounting hole (8), and the second area (22) of the adhesive layer (2) being connected with the top cover (7).

16. A battery comprising the cover plate assembly according to claim 15.

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