Protective film, cover plate assembly and battery

Abstract

The utility model provides a protective film, a cover plate assembly and a battery. The protective film comprises a first film layer, an adhesive layer and a second film layer, according to the technical scheme, the second film layer covers the first area of the adhesive layer, and due to the fact that the second film layer is located between the adhesive layer and the anti-explosion valve, when the protective film is under the conditions of thermal expansion and cold contraction and negative pressure and is sucked back, the situation that the protective film and the anti-explosion valve are bonded due to direct contact of the adhesive layer and the anti-explosion valve can be reduced; similarly, because the glue layer is whole-surface and not annular, compared with an annular gluing mode adopted for the anti-explosion valve film in the related technology, the technical scheme of the embodiment of the utility model omits the process step of removing part of glue on the anti-explosion valve film, namely, part of the glue layer located in the first area does not need to be removed, so that the anti-explosion valve film can be conveniently and rapidly glued. Therefore, the procedure before the protective film is adhered to the top cover of the battery can be reduced, and the production cost of the protective film is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a protective film, a cover plate assembly and a battery. Background Art

[0002] 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, it is necessary to set an explosion-proof valve film on the upper surface of the explosion-proof valve; generally, the explosion-proof valve film is bonded to the battery top cover by glue, and a commonly used method is to apply glue on the entire adhesive surface of the explosion-proof valve film or to apply a ring-shaped glue on the adhesive surface of the explosion-proof valve film.

[0003] Among them, the method of applying glue to the entire adhesive surface of the explosion-proof valve film may cause the explosion-proof valve film to be sucked back to adhere to the explosion-proof valve under thermal expansion and contraction and negative pressure, making the explosion-proof valve film uneven and easy to fall off; the method of applying ring-shaped glue to the adhesive surface of the explosion-proof valve film is to remove part of the glue to form a ring-shaped glue after applying glue to the entire adhesive surface of the explosion-proof valve film, which increases the number of steps for pasting the explosion-proof valve film, and compared with the method of applying glue to the entire adhesive surface of the explosion-proof valve film, the method of applying ring-shaped glue to the adhesive surface of the explosion-proof valve film also requires higher accuracy of the equipment, thereby increasing the cost. Utility Model Content

[0004] The embodiments of the utility model provide a protective film, a cover plate assembly and a battery, which can improve the problem that the explosion-proof valve film is uneven and easy to fall off, and is sucked back to adhere to the explosion-proof valve under negative pressure, thereby reducing the cost of annular glue coating.

[0005] In a first aspect, an embodiment of the present utility model provides a protective film, comprising:

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

[0007] An adhesive layer is attached to the mounting surface, the adhesive layer comprising a first area and a second area surrounding the first area; and

[0008] The second film layer is arranged on a side of the adhesive layer away from the first film layer and is located in the first area;

[0009] The second area of ​​the adhesive layer is configured to be connected to the top cover of the battery.

[0010] In one embodiment, the stacking direction of the first film layer, the adhesive layer and the second film layer is defined as the first direction, the thickness of the protective film in the first direction is H, and the thickness of the first film layer in the first direction is H1; wherein H and H1 satisfy: 1 / 3H≤H1≤2 / 3H.

[0011] In one embodiment, the stacking direction of the first film layer, the adhesive layer and the second film layer is defined as the first direction, the thickness of the protective film in the first direction is H, and the thickness of the adhesive layer in the first direction is H2; wherein H and H2 satisfy: 1 / 3H≤H2≤2 / 3H.

[0012] In one embodiment, H also satisfies:

[0013] 0.05mm≤H≤3mm.

[0014] In one embodiment, a vertical distance between a boundary line between the first region and the second region of the adhesive layer and a side line of the second region of the adhesive layer is defined as L; wherein L satisfies:

[0015] 0.1mm≤L≤6mm.

[0016] In one embodiment, at least one vent hole is disposed on the protective film. The vent hole is located in the first region and penetrates the protective film from the first film layer to the second film layer.

[0017] In one embodiment, the air-permeable hole includes at least one hole segment, and the hole segment is arranged in a strip shape.

[0018] In one embodiment, the hole width of the hole segment is defined as W, and the length of the hole segment in its extension direction is defined as L1; wherein W and L1 satisfy:

[0019] 0.05mm≤W≤0.5mm; and

[0020] 1.5mm≤L1≤3mm.

[0021] In one embodiment, there are multiple hole segments, and the multiple hole segments intersect and communicate with each other.

[0022] In one embodiment, the number of the hole segments is two, and the two hole segments are arranged in a cross shape.

[0023] In one embodiment, the first region includes a first sub-region and a second sub-region arranged around the first sub-region, and the second sub-region is located between the first sub-region and the second region;

[0024] The ventilation holes are located in the first sub-region.

[0025] In one embodiment, the material of the first film layer is one of polyethylene terephthalate, polyethylene and polyimide; and / or

[0026] The material of the second film layer is one of polyethylene terephthalate, polyethylene and polyimide.

[0027] In a second aspect, an embodiment of the present utility model provides a cover plate assembly, comprising:

[0028] A top cover, wherein a mounting hole is provided on the top cover;

[0029] an explosion-proof valve, disposed in the mounting hole; and

[0030] The protective film comprises the above-mentioned protective film, wherein the protective film cover is arranged on the mounting hole, and the second area of ​​the adhesive layer is connected to the top cover.

[0031] In a third aspect, an embodiment of the present utility model provides a battery, comprising the above-mentioned cover plate assembly.

[0032] Beneficial effects of the embodiments of the utility model:

[0033] In the technical solution of the present application, the first film layer, the glue layer and the second film layer are stacked in sequence to form a protective film, and the second film layer covers the first area of ​​the glue layer. Since the second film layer is located between the glue layer and the explosion-proof valve, when the protective film is in a state of thermal expansion and contraction and negative pressure and is sucked back, the glue layer can be reduced from being in direct contact with the explosion-proof valve and causing the protective film and the explosion-proof valve to be bonded together. Similarly, since the glue layer is a whole surface and not annular, compared with the related art of using annular glue coating on the explosion-proof valve film, the technical solution of the embodiment of the present application omits the process step of removing part of the glue on the explosion-proof valve film, that is, there is no need to remove part of the glue layer located in the first area, thereby reducing the process before the protective film is pasted to the top cover of the battery, thereby reducing the production cost of the protective film. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 It is a three-dimensional schematic diagram of a protective film provided by an embodiment of the utility model from one viewing angle;

[0036] Figure 2 It is a three-dimensional schematic diagram and a partial enlarged diagram of the protective film provided by the embodiment of the utility model from another viewing angle;

[0037] Figure 3 It is a structural schematic diagram and a partial enlarged diagram of the protective film provided by the embodiment of the utility model;

[0038] Figure 4 It is a schematic diagram of the structure of the adhesive layer provided in the embodiment of the utility model;

[0039] Figure 5 It is a schematic structural diagram of the first film layer provided in an embodiment of the utility model;

[0040] Figure 6 yes Figure 5 The enlarged schematic diagram of point A in the middle;

[0041] Figure 7 It is an exploded schematic diagram of a cover plate assembly provided in an embodiment of the utility model.

[0042] Reference numerals:

[0043] 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, dividing line; 5, edge line; 6, air vent; 61, hole section; 7, top cover; 8, mounting hole; 9, explosion-proof valve. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the utility model, and are not used to limit the utility model. In the utility model, unless otherwise stated, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0045] The utility model provides a protective film. Figures 1 to 6 These are some embodiments of the present application.

[0046] See also Figures 1 to 3 In some embodiments of the present application, the protective film 100 includes a first film layer 1, and the first film layer 1 is provided with a mounting surface 1A, and 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.

[0047] In some embodiments of the present application, the protective film 100 also includes an adhesive layer 2, which is attached to the mounting surface 1A; wherein the adhesive layer 2 may cover the entire surface of the mounting surface 1A, or may cover a portion of the mounting surface 1A, and this is not limited here; in a specific embodiment of the present application, the adhesive layer 2 is arranged on the entire surface of the mounting surface 1A, and when the corresponding glue coating operation is performed manually or by equipment on the first film layer 1, there is no need to control the glue coating range, and it is sufficient to ensure that the adhesive layer 2 is coated on the entire surface of the mounting surface 1A, and compared with the use of an annular adhesive layer for glue coating in the related art, part of the glue removal process is omitted. Similarly, the adhesive layer 2 is arranged on the entire surface of the mounting surface 1A, and the first film layer 1 and the adhesive layer 2 can also be produced by die-cutting, and a combined structure of the first film layer 1 and the adhesive layer 2 as in the embodiment of the present application is directly formed after die-cutting.

[0048] Among them, the adhesive layer 2 includes a first area 21 and a second area 22 arranged around the first area 21, and the second film layer 3 is arranged on the side of the adhesive layer 2 away from the first film layer 1 and is located in the first area 21; that is, the adhesive layer 2 located in the first area 21 can bond the first film layer 1 and the second film layer 3 to form a protective film 100; the adhesive layer 2 located in the second area 22 is in an exposed state, so as to be configured to be bonded to the top cover 7 of the battery, thereby realizing the connection between the protective film 100 and the battery top cover 7, so that the protective film 100 can protect the explosion-proof valve 9 in the top cover 7.

[0049] In the technical solution of the present application, the first film layer 1, the glue layer 2 and the second film layer 3 are stacked in sequence to form a 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 a state of thermal expansion and contraction and negative pressure and is sucked back, the glue layer 2 can be reduced from directly contacting the explosion-proof valve 9, thereby reducing the adhesion of the protective film 100 to the explosion-proof valve 9. Similarly, since the glue layer 2 is a whole surface and not annular, compared with the annular glue coating method for the explosion-proof valve film in the related art, the technical solution of the embodiment of the present application omits the process step of removing part of the glue on the explosion-proof valve film, that is, there is no need to remove part of the glue layer 2 located in the first area 21, 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.

[0050] 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 through the adhesive layer 2 to form a double-layer film structure, the thickness of the double-layer film structure is increased compared to the single-layer film, so that the structural hardness of the existing double-layer film is increased and the deformation resistance is stronger. Compared with the explosion-proof valve film in the related technology, it is less likely to deform and can effectively maintain the original shape under the conditions of thermal expansion and contraction and negative pressure.

[0051] It can be understood that in order to ensure the protective effect of the protective film 100 on the explosion-proof valve 9, the protective film 100 has a certain tensile strength and flexibility; in one 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).

[0052] To ensure the tensile strength and flexibility of the protective film 100, the present application has at least one of the above two embodiments. 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).

[0053] Among them, since the first film layer 1 is bonded to the top cover 7 of the battery through the adhesive layer 2, the thickness of the adhesive layer 2 and the thickness of the first film layer 1 together increase the overall thickness of the protective film 100, and at the same time, the protective film 100 can be more firmly attached to the top cover 7 of the battery; in some embodiments of the present application, the thickness of the protective film 100 in the first direction is defined as H, and the thickness of the first film layer 1 in the first direction is defined as H1; wherein H and H1 satisfy: 1 / 3H≤H1≤2 / 3H. That is, the thickness H1 of the first film layer 1 is set to meet this interval range, so that the attachment strength requirement of the protective film 100 can be met; if the value of H1 is less than 1 / 3H, the thickness of the first film layer 1 is too thin, so there may be a problem of low attachment 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.

[0054] It should be noted that the first direction is Figure 3 The X direction in FIG. 1 is the stacking direction of the first film layer 1 , the adhesive layer 2 and the second film layer 3 , and the first direction X is used in the following description.

[0055] In some embodiments of the present application, the thickness of the adhesive layer 2 in the first direction X is defined as H2; wherein H and H2 satisfy: 1 / 3H≤H2≤2 / 3H. The thickness H2 of the adhesive layer 2 is set to satisfy this interval range because the adhesive layer 2 mainly plays a bonding role. Such a setting can make the adhesive layer 2 meet the adhesive strength requirements of the protective film 100, and at the same time, it can also avoid the thickness of the adhesive layer 2 being too thick to affect 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 adhesion effect between the first film layer 1 and the second film layer 3 and the first film layer 1 and the top cover 7 of the battery. If the value of H2 is greater than 2 / 3L, 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 production cost of the adhesive layer 2.

[0056] 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, and can also effectively reduce the material cost of the protective film 100. If the H value is less than 0.05mm, the thickness of the protective film 100 may be too thin, resulting in poor adhesion; if the H value is greater than 3mm, the material cost of the protective film 100 increases. Wherein, 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 within the numerical range are also applicable.

[0057] See also Figure 3 and Figure 4 In some embodiments of the present application, the vertical distance between the boundary line 4 between the first area 21 and the second area 22 of the adhesive layer 2 and the edge line 5 of the second area 22 of the adhesive layer 2 is defined as L; wherein L satisfies: 0.1mm≤L≤6mm. It can be understood that the value of L determines the area size of the second area 22. Setting L to meet this interval range can improve the tolerance range of the protective film 100 during pasting, and at the same time, can also improve the adhesion of the protective film 100.

[0058] If the value of L is less than 0.1mm, the size of the glue layer 2 located in the second area 22 is too small. Since the glue layer 2 in the second area 22 is bonded to the top cover 7 of the battery, the protective film 100 has higher requirements on the accuracy of the positioning equipment when it is pasted to the window position of the explosion-proof valve 9, and the tolerance range of pasting is smaller. At the same time, the contact area between the glue layer 2 in the second area 22 and the top cover 7 is small, resulting in poor adhesion of the protective film 100; if the value of L is greater than 6mm, the size of the glue layer 2 in the second area 22 is too large, which not only has little improvement on the deformation resistance of the protective film 100 under vacuum baking and negative pressure conditions, but also increases the material cost of the protective film 100.

[0059] Wherein, the value of L can be 0.1mm, 0.3mm, 0.5mm, 0.7mm, 0.9mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4mm, 4.2mm, 4.4mm, 4.6mm, 4.8mm, 5mm, 5.2mm, 5.4mm, 5.6mm, 5.8mm, 6mm. The value of L is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0060] In addition, the vertical distances from the boundary line 4 between the first region 21 and the second region 22 to the side line 5 of the second region 22 can be the same or different, and there is no limitation here, as long as the L value meets the range of the above embodiment. Figure 4 , dividing line 4 is Figure 4 The dotted line portion indicated by the arrow 4 in the figure.

[0061] See also Figure 5 , at least one air hole 6 is provided on the protective film 100; 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. Among them, the provision of the air hole 6 allows the space formed between the explosion-proof valve 9, the protective film 100 and the top cover 7 to be connected to the external environment, ensuring that there is no pressure difference between the space formed between the explosion-proof valve 9, the protective film 100 and the top cover 7 and the outside world, so as to avoid the problem that the protective film 100 is uneven and easy to fall off due to thermal expansion and contraction and negative pressure, thereby affecting the appearance of the battery. It can be understood that there is no limit to the number of air holes 6, which can be one or more. Similarly, there is no limit to the shape of the air hole 6, which can be circular, polygonal or special-shaped.

[0062] Furthermore, in some embodiments of the present application, the air vent 6 includes at least one hole segment 61, and the hole segment 61 is arranged in a strip shape. That is, the air vent 6 can be composed of one hole segment 61, or a combination of multiple hole segments 61; and the shape of the air vent 6 can be a straight line, an L shape, or a cross shape, etc., which is not limited here.

[0063] See also Figure 6 In some embodiments of the present application, the hole width of the hole section 61 is defined as W; wherein W satisfies: 0.05mm≤W≤0.5mm. That is, the W value satisfies this interval range, which can meet the air permeability requirements of the protective film 100 and prevent dust and foreign matter from entering the space formed between the explosion-proof valve 9, the protective film 100 and the top cover 7; if the W value is less than 0.05mm, the air vent 6 cannot meet the air permeability requirements of the protective film 100; if the W value is greater than 0.5mm, the size of the air vent 6 is too large and cannot provide better protection against dust and foreign matter. Among them, the W value 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 numerical range are also applicable.

[0064] In some embodiments of the present application, the length of the hole segment in its extension direction is defined as L1; wherein L1 satisfies: 1.5mm≤L1≤3mm. That is, setting the L1 value to satisfy this interval can meet the ventilation requirements of the protective film 100 and prevent dust and foreign matter from entering the space formed between the explosion-proof valve 9, the protective film 100 and the top cover 7; if L1 is greater than 3mm, the size of the air hole 6 is too large, and it cannot provide a better protection against dust and foreign matter. At the same time, the tensile strength and flexibility of the protective film 100 may also be affected due to the excessive size of the air hole 6; if the L1 value is less than 1.5mm, the air hole 6 cannot meet the ventilation requirements of the 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 the numerical range are also applicable.

[0065] In some embodiments of the present application, there are multiple hole segments 61, and the multiple hole segments 61 intersect and communicate with each other. That is, in this embodiment, two hole segments 61 may intersect to form the air vent 6, three hole segments 61 may intersect to form the air vent 6, or more than three hole segments 61 may intersect to form the air vent 6, and this is not limited here.

[0066] 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 6 is a cross hole, and the lengths of the two hole segments 61 in their respective extension directions are the length and width dimensions of the air vent 6; based on the fact that the W value and L1 value of the above-mentioned hole segment 61 are both limited, the length and width dimensions of the cross hole are both between 1.5 mm and 3 mm.

[0067] In addition, there is no restriction on the opening position of the air hole 6, which can be 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 connected to the external environment. In some embodiments of the present application, the first area 21 includes a first sub-area 211 and a second sub-area 212 arranged around the first sub-area 211, and the second sub-area 212 is located between the first sub-area 211 and the second area 22; wherein the air hole 6 is located in the first sub-area 211. Among them, the second area 22 is the edge area of ​​the protective film 100. Such an arrangement avoids the opening position of the air hole 6 being close to the second area 22, and when the protective film 100 is sucked back, it will not cause the part of the first film layer 1 to be loosely adhered to the top cover 7 of the battery, and at the same time, it can also improve the aesthetics of the protective film 100.

[0068] In addition, please refer to Figure 4 The dotted line portion between the first sub-region 211 and the second sub-region 212 is a boundary line between the first sub-region 211 and the second sub-region 212 .

[0069] See also Figure 7 The utility model further proposes 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, the explosion-proof valve 9 is arranged in the mounting hole 8, the protective film 100 is as described above, the protective film 100 is covered on the mounting hole 8, and the second area 22 of the adhesive layer 2 is connected to the top cover 7. Since the cover plate assembly adopts all the technical solutions of all the above embodiments, it has at least the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here one by one.

[0070] The protective film 100 is covered on the mounting hole 8 to protect the explosion-proof valve 9 located in the mounting hole 8 .

[0071] Furthermore, the utility model also proposes a battery, the battery includes a cover assembly, the cover assembly is as described above, since the battery adopts all the technical solutions of all the above embodiments, it at least has the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0072] The above is a detailed introduction to the embodiments of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for technicians in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A protective film, characterized in that: include: The first film layer is provided with a mounting surface, and the mounting surface is located on one side of the first film layer; An adhesive layer, attached to the mounting surface, the adhesive layer comprising a first area and a second area arranged around the first area; and A second film layer is disposed on a side of the adhesive layer away from the first film layer and is located in the first region; Wherein, the second area of ​​the adhesive layer is configured to be connected to the top cover of the battery.

2. The protective film according to claim 1, characterized in that: The stacking direction of the first film layer, the glue layer and the second film layer is defined as a first direction, the thickness of the protective film in the first direction is H, and the thickness of the first film layer in the first direction is H1; wherein H and H1 satisfy: 1 / 3H≤H1≤2 / 3H.

3. The protective film according to claim 1, characterized in that: The stacking direction of the first film layer, the adhesive layer and the second film layer is defined as a first direction, the thickness of the protective film in the first direction is H, and the thickness of the adhesive layer in the first direction is H2; wherein H and H2 satisfy: 1 / 3H≤H2≤2 / 3H.

4. The protective film according to claim 2 or 3, characterized in that: The H also satisfies: 0.05mm≤H≤3mm.

5. The protective film according to any one of claims 1 to 3, characterized in that: The vertical distance between the boundary line between the first area and the second area of ​​the adhesive layer and the edge line of the second area of ​​the adhesive layer is defined as L; wherein L satisfies: 0.1mm≤L≤6mm.

6. The protective film according to any one of claims 1 to 3, characterized in that: At least one vent hole is disposed on the protective film. The vent hole is located in the first region and penetrates the protective film from the first film layer to the second film layer.

7. The protective film according to claim 6, characterized in that: The ventilation hole includes at least one hole segment, and the hole segment is arranged in a strip shape.

8. The protective film according to claim 7, characterized in that: The hole width of the hole segment is defined as W, and the length of the hole segment in its extension direction is defined as L1; wherein W and L1 satisfy: 0.05mm≤W≤0.5mm; and 1.5mm≤L1≤3mm.

9. The protective film according to claim 7, characterized in that: There are multiple hole segments, and the multiple hole segments intersect and communicate with each other.

10. The protective film according to claim 7, characterized in that: The number of the hole segments is two, and the two hole segments are arranged in a cross shape.

11. The protective film according to claim 6, characterized in that: The first region includes a first sub-region and a second sub-region arranged around the first sub-region, and the second sub-region is located between the first sub-region and the second region; Wherein, the ventilation hole is located in the first sub-region.

12. The protective film according to any one of claims 1 to 3, characterized in that: The material of the first film layer is one of polyethylene terephthalate, polyethylene and polyimide; and / or The material of the second film layer is one of polyethylene terephthalate, polyethylene and polyimide.

13. A cover plate assembly, characterized in that: include: A top cover, wherein a mounting hole is provided on the top cover; An explosion-proof valve, arranged in the mounting hole; and A protective film, comprising the protective film according to any one of claims 1 to 12, wherein the protective film cover is arranged on the mounting hole, and the second area of ​​the adhesive layer is connected to the top cover.

14. A battery, characterized in that: Comprising the cover plate assembly as claimed in claim 13.

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