Power battery wrapping film and power battery applying same

Abstract

The utility model discloses a power battery wrapping film which comprises at least one PET (polyethylene terephthalate) layer and at least one adhesive layer, and the PET layers and the adhesive layers are alternately compounded in sequence; wherein the PET layer between any two adjacent adhesive layers is provided with a plurality of pore structures which extend along the thickness direction of the PET layer and penetrate through the PET layer, so that any two adjacent adhesive layers are communicated through the pore structures. The adjacent adhesive layers are communicated through the pore structures, so that the adhesive property between the adhesive layers can be enhanced, the shearing force between the film layers can be improved, and the problems of interlayer slippage and falling caused by low surface energy of the PET layer and insufficient shearing strength between the film layers can be effectively solved on the basis of not changing the existing process route; and the protection effect of the wrapping film on the power battery is enhanced. For the adjacent PET layer and adhesive layer, the adhesive of the adhesive layer is embedded into the pore structure to form an embedded structure on the contact interface of the adhesive layer and the PET layer, so that a mechanical interlocking effect is formed between the PET layer and the adhesive layer, the adhesive property between the PET layer and the adhesive layer is improved, the stability between the film layers is improved, and the service life of the film is prolonged. The problems of interlayer slippage and falling of the wrapping film are further improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of adhesive, especially relates to a wrapping film for power battery and power battery applying same. BACKGROUND

[0002] In today's era, the new energy automobile industry is developing rapidly, and the safety performance of the power battery has undoubtedly become the focus of manufacturers and consumers. The wrapping film plays a protective role in the manufacturing, assembly and use of the power battery. As a key barrier to ensure the safety of the power battery, the technical progress of the battery wrapping material plays a decisive role in improving the safety performance of the whole vehicle.

[0003] The basic structure of the power battery wrapping film in the prior art adopts a composite structure of double-layer PET (polyethylene terephthalate) substrate + adhesive layer. For example, a vehicle-mounted lithium ion battery wrapping blue film disclosed in patent No. 202223152916.8 includes a first PET film layer and a second PET film layer, and a blue glue layer is arranged between the first PET film layer and the second PET film layer. In addition, a battery noise reduction wrapping material and a preparation method thereof disclosed in application No. 202311804872.9 include a first adhesive layer, a first PET substrate, a second adhesive layer and a second PET substrate which are stacked in sequence.

[0004] Such a structure design has the following defects and deficiencies: since the PET substrate belongs to a low surface energy material, the adhesive force between the adhesive layers and the PET substrates is very limited. When the power battery pack is subjected to external force impact, the adhesive layer is easily damaged from the interface between the PET substrates, resulting in slippage and falling off, and thus reducing the insulation protection function of the wrapping film and easily causing electrical disasters and other safety hazards.

[0005] Therefore, it is of great value and significance to study the power battery wrapping film adhesive tape with improved interlayer adhesion performance to improve the safety performance of the power battery. CONTENT OF THE UTILITY MODEL

[0006] In order to overcome the technical problem of poor interlayer adhesion of the traditional power battery wrapping film, which easily causes interlayer slippage and falling off, the utility model provides a power battery wrapping film and a power battery applying same.

[0007] The utility model adopts the technical scheme of:

[0008] A power battery wrapping film comprises a PET layer and an adhesive layer, the number of layers of the PET layer and the adhesive layer is at least greater than one, and the PET layer and the adhesive layer are alternately compounded in sequence; wherein the PET layer between any two adjacent adhesive layers has a plurality of aperture structures extending along the thickness direction of the PET layer and arranged through the PET layer, so that any two adjacent adhesive layers are connected through the aperture structures.

[0009] Further, the aperture structure has a pore size of 10-500 μm.

[0010] Further, the PET layer has a porosity of 3-50%.

[0011] Further, the cross-sectional shape of the aperture structure is at least one of regular or irregular circular, diamond, square, star shape.

[0012] Further, the PET layer comprises a first PET layer and a second PET layer, the adhesive layer comprises a first adhesive layer and a second adhesive layer, and the first PET layer, the first adhesive layer, the second PET layer and the second adhesive layer are compounded in sequence; wherein the second PET layer is provided with the aperture structure.

[0013] Further, at least one of the first PET layer and the second PET layer is a colored layer.

[0014] Further, the thickness of the second PET layer is 5-40 μm, and the thickness of the power battery wrapping film is 30-150 μm.

[0015] Further, the power battery wrapping film further comprises a release layer, one side of the power battery wrapping film is the PET layer, and the other side opposite to the PET layer is the release layer.

[0016] Further, the thickness of the release layer is 15-50 μm.

[0017] Based on the same design idea, the utility model further provides a power battery applying the above power battery wrapping film, and the power battery further comprises a battery cell, and the power battery wrapping film is wrapped on the outer surface of the battery cell.

[0018] In summary, the power battery wrapping film provided by the utility model has at least the following technical effects compared with the prior art:

[0019] The utility model discloses a power battery wrapping film, which comprises a plurality of PET layers and a plurality of adhesive layers which are alternately and sequentially compounded, a plurality of pore structures penetrating through the PET layer in the thickness direction are arranged between the adjacent two adhesive layers, and the pore structures are filled with the adhesive of the adhesive layer after the wrapping film is formed.

[0020] In addition, compared with the traditional solid film layer, the PET layer of the present application can reduce the shear modulus and bulk modulus of the film material by adopting the multi-pore structure design, reduce the phenomenon that the edges and corners of the wrapping film are prone to natural warping after wrapping the battery cell, and improve the bending degree at the micro level. When the wrapping film is bent to wrap the power battery or is stretched, the wrapping film is provided with a certain deformation space, thereby improving the flexibility of the wrapping film and further strengthening the protection effect of the wrapping film on the power battery. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 FIG. 1 is a schematic view of the interlayer structure of the power battery wrapping film of the utility model;

[0022] Figure 2 FIG. 2 is an expanded schematic view of the planar extension direction of the second PET layer of the utility model;

[0023] Figure 3 FIG. 3 is a schematic view of the structure of the power battery of the utility model.

[0024] In the drawings, the meanings of the reference signs are as follows:

[0025] 1, power battery wrapping film; 2, first PET layer; 3, first adhesive layer; 4, second PET layer; 5, second adhesive layer; 6, release layer; 7, pore structure; 8, battery cell. DETAILED DESCRIPTION

[0026] In order to better understand and implement, the technical solutions in the embodiments of the utility model will be clearly and completely described below in combination with the drawings in the embodiments of the utility model.

[0027] In the description of the utility model, it is necessary to explain that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the utility model belongs. The terms used in the specification of the utility model herein are only for the purpose of describing specific embodiments and are not intended to limit the utility model.

[0029] According to the technical scheme of the utility model, the power battery wrapping film 1 comprises a PET layer and an adhesive layer, the number of layers of the PET layer and the adhesive layer is at least greater than one, and the PET layer and the adhesive layer are alternately and sequentially compounded, that is, after the product is formed, the interlayer structure of the power battery wrapping film 1 is arranged in the form of "PET layer-adhesive layer-PET layer-adhesive layer..." For example, taking the number of PET layers and adhesive layers as two layers, the interlayer structure of the power battery wrapping film 1 is: PET layer-adhesive layer-PET layer-adhesive layer.

[0030] The PET (polyethylene terephthalate) layer is used as the base material structure of the entire power battery wrapping film 1, and because it is an insulating material, it can be used to play an insulating protection role after wrapping the power battery. The purpose of the adhesive layer provided on the power battery wrapping film 1 is: on the one hand, the outermost adhesive layer can be tightly bonded with the outer surface of the power battery, realizing the fixing and wrapping effect of the power battery wrapping film 1 on the battery; on the other hand, the adhesive layer between the layers can realize the tight bonding between the two adjacent PET layers, so that the power battery wrapping film 1 can form a multi-film layer composite structure with the PET layer and the adhesive layer arranged alternately, improving the overall structural strength and stability.

[0031] Referring to Figure 2As shown, in the technical scheme of the utility model, the PET layer between any two adjacent adhesive layers has a plurality of pore structures 7, the pore structure 7 extends along the thickness direction of the PET layer and is arranged through the PET layer, after the power battery wrapping film 1 is formed, the pore structure 7 is filled by the adhesive of the adhesive layer, so that any two adjacent adhesive layers are communicated through the pore structure 7. For the adjacent adhesive layers, the communication is realized through the pore structure 7, the bonding performance between the adhesive layers can be enhanced, the shear force between the film layers is improved, the interlayer slip and falling problem caused by the low surface energy of the PET layer and the insufficient shear strength between the film layers is effectively solved on the basis of not changing the existing process route, and the protection effect of the power battery wrapping film 1 on the power battery is strengthened. For the adjacent PET layer and adhesive layer, at the contact interface of the adhesive layer and the PET layer, the adhesive of the adhesive layer is embedded in the pore structure 7 to form an embedded structure, so that the mechanical interlocking effect is formed between the PET layer and the adhesive layer, the bonding performance between the two is improved, the stability between the film layers is improved, and the interlayer slip and falling problem of the power battery wrapping film 1 is further improved.

[0032] More specifically, compared with the traditional solid film layer, the PET layer of the scheme can reduce the shear modulus and bulk modulus of the film material by adopting the porous structure design, reduce the natural warping phenomenon of the edge corner of the power battery wrapping film 1 after wrapping the battery cell, and improve the bending degree at the microscopic level. When the power battery wrapping film 1 is bent to wrap the power battery or is stretched, a certain deformation space is provided for the wrapping film, so that the flexibility of the wrapping film is improved, and the protection effect of the power battery wrapping film 1 on the power battery is further strengthened.

[0033] Preferably, referring to Figure 2 As shown, the pore structure 7 of the PET layer can be regularly arranged or irregularly arranged. The cross-sectional shape of the pore structure 7 can be at least one of regular or irregular circular, diamond, square, star shapes. In particular, from the perspective of process convenience, the cross section of the pore structure 7 is preferably set to a circular shape.

[0034] Preferably, the pore size of the pore structure 7 is 10-500 μm, and preferably 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm.

[0035] Preferably, for the PET layer provided with the pore structure 7, the porosity size is 3-50%, and preferably 3%, 10%, 20%, 30%, 40% or 50%.

[0036] Further, referring to Figure 1As shown, the power battery wrapping film 1 further comprises a release layer 6, one side of the power battery wrapping film 1 is a PET layer, and the other side away from the PET layer is the release layer 6. Among them, the release layer 6 is used to protect the adhesive layer (such as the second adhesive layer 5 shown in the embodiment) on the outermost side of the power battery wrapping film 1, which can prevent the outermost adhesive layer from delamination and peeling off when the power battery wrapping film 1 is unwound. Figure 1

[0037] Preferably, the thickness of the release layer 6 is 15-50 μm, and preferably 15 μm, 20 μm, 30 μm, 40 μm or 50 μm.

[0038] Embodiment 1

[0039] In a preferred embodiment of the utility model, a specific structure design scheme of the power battery wrapping film 1 is provided.

[0040] Referring to Figure 1 and Figure 2 As shown, in the technical scheme of this embodiment, the PET layer comprises a first PET layer 2 and a second PET layer 4, the adhesive layer comprises a first adhesive layer 3 and a second adhesive layer 5, and the first PET layer 2, the first adhesive layer 3, the second PET layer 4 and the second adhesive layer 5 are sequentially compounded. Among them, the second PET layer 2 is provided with a pore structure 7, and the first PET layer 2 is not provided with a pore structure 7, that is, it is a solid film layer structure formed by PET film material.

[0041] Specifically, the first PET layer 2 is located on the outermost side of the power battery wrapping film 1, and its main function is as a substrate structure, and since it is an insulating material, it can be used to play an insulating protection role after wrapping the power battery. The second PET layer 2 is located in the interlayer structure and is used as an internal structure reinforcing layer to improve the overall structural strength and stability of the multi-film layer composite structure, and its pore structure 7 can be used to fill the adhesive of the first adhesive layer 3 and the second adhesive layer 5 on the adjacent two sides to enhance the bonding performance between the adhesive layers and the stability between the film layers. The first adhesive layer 3 is located in the interlayer structure and is used to realize the close bonding between the first PET layer 2 and the second PET layer 4, so that the power battery wrapping film 1 can form a multi-film layer composite structure with alternating PET layers and adhesive layers. The second adhesive layer 5 is located on the outermost side of the power battery wrapping film 1 away from the first PET layer 2, and is used to be closely bonded with the outer surface of the power battery to realize the fixing and wrapping of the power battery by the power battery wrapping film 1.

[0042] In a preferred scheme of this embodiment, at least one of the first PET layer 2 and the second PET layer 4 is a colored layer. The so-called colored layer is a functional layer 3 provided with a color different from other film layers, which is used to play a color identification role, facilitating identification and thus completing the film pasting operation.

[0043] ​The color of the colored layer can be set to any one of blue, green, brown, tan and black, and preferably blue.

[0044] In particular, since the first PET layer 2 is located at the outermost side of the power battery wrapping film 1, the first PET layer 2 is preferably set as a colored layer, and the color thereof is blue, thereby further facilitating identification of the film.

[0045] Further, the thickness of the second PET layer 4 is 5-40 μm, and preferably 5 μm, 15 μm, 25 μm, 35 μm or 40 μm.

[0046] The thickness of the power battery wrapping film 1 is 30-150 μm, and preferably 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm or 150 μm.

[0047] Preparation Example 1

[0048] Specifically, in the present preparation example:

[0049] (1) The PET film with a thickness of 25 μm is used as the first PET layer 2 and the second PET layer 4.

[0050] (2) The acrylate type glue or adhesive is used as the glue for forming the first adhesive layer 3 and the second adhesive layer 5, and in actual application, other existing glue or adhesive (such as acrylic glue or hot melt glue, etc.) can also be used to form the first adhesive layer 3 and the second adhesive layer 5.

[0051] (3) The plurality of uniformly distributed circular pore structures 7 are formed on the second PET layer 4 by mechanical punching or tensile hole forming, wherein the pore diameter of the pore structure 7 is 10 μm, and the porosity of the second PET layer 4 is 5%.

[0052] Based on the above material information, the power battery wrapping film 1 is prepared according to the following process:

[0053] The glue or adhesive for forming the second adhesive layer 5 is coated on the surface of the release layer 6 by a coating machine using a coating process, and the second adhesive layer 5 is formed, wherein the thickness of the second adhesive layer 5 is 10 μm; then the second PET layer 4 is attached to the side of the second adhesive layer 5 away from the release layer 6; the glue or adhesive for forming the first adhesive layer 3 is coated on the surface of the second PET layer 4 away from the second adhesive layer 5, and the first adhesive layer 3 is formed, wherein the thickness of the first adhesive layer 3 is 10 μm; then the first PET layer 2 is attached to the surface of the first adhesive layer 3.

[0054] Thus, a plurality of power battery wrapping films 1 of Preparation Example 1 are obtained.

[0055] Preparation Example 2

[0056] The preparation example refers to the preparation of a number of power battery wrapping films 1 according to Preparation Example 1, and the difference between Preparation Example 1 is that the thickness of the first PET layer 2 and the second PET layer 4 in this preparation example is 35 μm, the pore size of the pore structure 7 is 10 μm, and the porosity of the second PET layer 4 is 5%. In addition to the above differences, the other materials used to prepare the power battery wrapping film 1 and the related preparation process of this preparation example are consistent with Preparation Example 1.

[0057] Preparation Example 3

[0058] Specifically, in this preparation example:

[0059] (1) The PET film with a thickness of 25 μm is used as the first PET layer 2 and the second PET layer 4.

[0060] (2) Acrylate glue or adhesive is used as the glue for forming the first adhesive layer 3 and the second adhesive layer 5. In actual application, other existing glues or adhesives (such as acrylic glue or hot melt glue, etc.) can also be used to form the first adhesive layer 3 and the second adhesive layer 5.

[0061] Based on the above material information, the power battery wrapping film 1 is prepared according to the following process:

[0062] The glue or adhesive used to form the second adhesive layer 5 is coated on the surface of the release layer 6 by a coating machine to form the second adhesive layer 5, wherein the thickness of the second adhesive layer 5 is 10 μm; then the second PET layer 4 is attached to the side of the second adhesive layer 5 away from the release layer 6; the glue or adhesive used to form the first adhesive layer 3 is coated on the surface of the second PET layer 4 away from the second adhesive layer 5 to form the first adhesive layer 3, and the thickness of the first adhesive layer 3 is 10 μm; then the first PET layer 2 is attached to the surface of the first adhesive layer 3.

[0063] Thus a number of power battery wrapping films 1 of Preparation Example 3 are obtained.

[0064] Preparation Example 4

[0065] The preparation example refers to the preparation of a number of power battery wrapping films 1 according to Preparation Example 3, and the difference between Preparation Example 3 is that the thickness of the first PET layer 2 and the second PET layer 4 in this preparation example is 35 μm. In addition to the above differences, the other materials used to prepare the power battery wrapping film 1 and the related preparation process of this preparation example are consistent with Preparation Example 3.

[0066] Test Example

[0067] 1. Test object

[0068] The power battery wrapping film 1 prepared in Preparation Example 1-4 is taken as a test object.

[0069] 2. Tensile shear strength test

[0070] The power battery wrapping film 1 prepared in Preparation Example 1-4 is respectively subjected to shear performance test according to shear force test standard GB / T 7124-2008. During the test, the tensile testing machine is tested at a constant test speed, the test speed of the shear strength is 5 mm / min, the general breaking time is 60±5S, the maximum load of the shear breaking of the test sample is recorded as the breaking load (N), and the experimental result is expressed as the arithmetic mean value of the tensile shear strength (MPa) of the effective test sample, which is calculated by dividing the breaking load (N) by the shear area (mm2).

[0071] 3. Peeling force test

[0072] The power battery wrapping film 1 prepared in Preparation Example 1-4 is respectively subjected to peeling force test according to peeling force test standard ASTM D 3330. During the test, the test object is laid on a steel plate, the second adhesive layer 5 faces the steel plate, and the other side of the test object is sequentially pasted with a 5000NS adhesive tape and a steel plate. The steel plates respectively arranged on the two sides of the test object are clamped by a Jianjian tensile tester to test the peeling force, the peeling speed is 300 mm / min, the peeling angle is 180°, the peeling force data is recorded, the average value of a length of 60 mm after the reading is stable is taken (if a serious jagged curve appears, the average value of the maximum value of the curve every 10 mm after the curve is stable is taken), and the average value of 5 parallel samples is taken as the judgment standard.

[0073] 4. Test results

[0074] The test results are shown in Table 1. In this test example, the power battery wrapping film 1 provided with the pore structure 7 is far superior to the power battery wrapping film 1 without the pore structure 7 in terms of shear strength and peeling force performance. Therefore, by providing the pore structure 7 in the PET layer in the interlayer structure, the bonding performance between the strong adhesive layers can be significantly enhanced, the shear force between the film layers can be improved, the slipping and falling problems of the wrapping film between the film layers can be improved, and the protection effect of the wrapping film on the power battery can be improved.

[0075] Table 1. Test result statistics of the test example

[0076] Group Shear strength (MPa) Peeling force (N / mm) Preparation Example 1 5.8 0.69 Preparation Example 2 5.5 0.65 Preparation Example 3 4.1 0.52 Preparation Example 4 3.7 0.49

[0077] Example 2

[0078] Based on the same design idea, the utility model also provides an embodiment about a power battery, and the power battery of the embodiment applies the power battery wrapping film 1 described in the above embodiment.

[0079] Referring toFigure 3 As shown in the technical scheme of the embodiment, the power battery includes the battery cell 8, and the power battery wrapping film 1 is wrapped on the outer surface of the battery cell 8. Under the close bonding wrapping effect of the power battery wrapping film 1, the battery cell 8 of the power battery can be fixed and protected. In addition, in the case of external force impact and the like, since the adjacent adhesive layers of the power battery wrapping film 1 are connected through the pore structure, the bonding performance between the adhesive layers can be enhanced, the shear force between the film layers can be improved, and the interlayer slip and falling off of the film layers are not prone to occur; and since the adhesive of the adhesive layer is embedded in the pore structure at the contact interface to form an embedded structure, the mechanical interlocking effect between the functional layer and the adhesive layer is formed, the stability between the film layers is improved, the interlayer slip and falling off of the wrapping film are further improved, and the protection effect of the power battery wrapping film 1 on the battery cell 8 is enhanced.

[0080] The technical means disclosed in the utility model scheme is not limited to the technical means disclosed in the above-mentioned embodiment, and also includes the technical scheme composed of any combination of the above technical features. It should be pointed out that, for ordinary skilled persons in the art, without departing from the principle of the utility model, some improvements and refinements can be made, and these improvements and refinements are also considered to be within the protection scope of the utility model.

Claims

1. A power battery wrapping film, characterized in that, The power battery wrapping film comprises a PET layer and an adhesive layer, the number of layers of the PET layer and the adhesive layer is at least greater than one, and the PET layer and the adhesive layer are alternately and sequentially compounded; wherein the PET layer between any two adjacent adhesive layers has a plurality of aperture structures extending along the thickness direction of the PET layer and arranged through the PET layer, so that any two adjacent adhesive layers are connected through the aperture structures.

2. The power battery wrapping film according to claim 1, wherein, The aperture structure has a pore size of 10-500 μm.

3. The power battery wrapping film of claim 1, wherein, The PET layer has a porosity of 3-50%.

4. The power battery wrapping film according to any one of claims 1-3, wherein, The cross-sectional shape of the aperture structure is at least one of a circular shape, a diamond shape, a square shape, and a star shape.

5. The power battery wrapping film of claim 1, wherein, The PET layer comprises a first PET layer and a second PET layer, the adhesive layer comprises a first adhesive layer and a second adhesive layer, and the first PET layer, the first adhesive layer, the second PET layer, and the second adhesive layer are sequentially compounded; wherein the second PET layer is provided with the aperture structure.

6. The power battery wrapping film according to claim 5, wherein, At least one of the first PET layer and the second PET layer is a colored layer.

7. The power battery wrapping film according to claim 5, wherein, The thickness of the second PET layer is 5-40 μm, and the thickness of the power battery wrapping film is 30-150 μm.

8. The power battery wrapping film of claim 1, wherein, The power battery wrapping film further comprises a release layer, one side of the power battery wrapping film is the PET layer, and the other side opposite to the PET layer is the release layer.

9. The power battery wrapping film of claim 8, wherein, The thickness of the release layer is 15-50 μm.

10. A power battery wrapped with the power battery wrapping film according to any one of claims 1-9, characterized in that, The power battery further comprises a battery cell, and the power battery wrapping film is wrapped on the outer surface of the battery cell.

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