Enhanced easy-to-exhaust battery core wrapping film

Abstract

The utility model discloses a reinforced battery core wrapping film easy to exhaust. The reinforced battery core wrapping film comprises a base material layer, a structural reinforcer arranged on the base material layer, a thermosensitive layer and an exhaust channel arranged on the thermosensitive layer. Wherein the structural reinforcer is used for improving the overall structural strength of the wrapping film and preventing the wrapping film from being bent in a natural state to influence a shell entering process, and the wrapping film has relatively high structural performance under the condition that the thickness of a film material does not need to be increased, so that the design space of the battery cell is prevented from being compressed and the energy density of the battery cell is prevented from being reduced. The exhaust channel is used for providing a flowing channel for exhausting gas generated in the high-temperature hot-pressing process and reducing the moving distance when the gas is exhausted, so that bubbles in the wrapping film can be exhausted in time, the overall film surface flatness of the wrapping film after a battery cell is wrapped is improved, the effective bonding area of the thermosensitive layer is increased, the bonding effect of the wrapping film is optimized, and the service life of the wrapping film is prolonged. And the bonding and fitting stability between the wrapping film and the battery cell is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of adhesives, in particular to a wrapping film applied to a bare battery cell. Background Art

[0002] The battery cell wrapping film is an adhesive tape used to wrap a power battery cell into a shell, protecting the battery cell from piercing the diaphragm by the shell during the process of inserting the battery cell into the shell, and reducing the local short circuit of the battery cell caused by the rupture of the diaphragm.

[0003] At present, most of the commonly used battery cell wrapping films have a structure of mylar film + hot melt adhesive. For example, the Chinese patent application with the publication number CN117080692A discloses a battery cell mylar film, an energy storage device and an electrical equipment using the same, and the battery cell mylar film is wrapped around the outer periphery of the bare battery cell; the Chinese patent with the publication number CN219267771U provides a battery cell and a battery, which includes a mylar film and a battery cell, and the mylar film is adhered to the battery cell through an adhesive layer. However, such a structural design has the following defects:

[0004] 1) For the convenience of use, the battery cell wrapping film needs to have appropriate stiffness. Otherwise, it will affect the shell insertion process due to bending in the natural state. Conventional mylar films have poor heat resistance and low elastic modulus. Therefore, the mylar film needs to be thickened and specially heat-treated, resulting in inconvenient film application and occupying a large space of the battery cell. Moreover, the increase in the film thickness will compress the design space of the battery cell and reduce the energy density of the battery cell, which is not conducive to industrial production and use;

[0005] 2) When the hot melt adhesive enters the shell, it is in direct contact with the bare battery cell. During the hot pressing and bonding process, there may be irregular gaps between the two, which are filled with gas. After hot pressing and bonding, the melted hot melt adhesive hinders the discharge of some gas, and the gas finally remains inside the tape to form bubbles, affecting the flatness of the film surface of the wrapping film, and further affecting the bonding stability between the wrapping film and the battery cell.

[0006] Therefore, there is an urgent need in the prior art to invent a battery cell wrapping film that can ensure structural strength under low thickness conditions and improve the flatness of the film surface after wrapping the battery cell. Summary of the Utility Model

[0007] In order to overcome the technical problems of the battery cell wrapping film in the prior art, such as affecting the shell insertion process due to low structural strength, affecting the shell insertion process and compressing the design space of the battery cell due to large thickness, and affecting the flatness of the film surface due to the presence of bubbles during the hot pressing process, the utility model provides a battery cell wrapping film with the characteristics of low thickness, high structural strength and good exhaust performance.

[0008] The technical solution adopted by the utility model to solve its problems is:

[0009] The utility model provides a reinforced and easily exhaustible cell wrapping film, which comprises a wrapping film body. The wrapping film body includes a base material layer and a thermal-sensitive layer; a structural reinforcement member disposed on the base material layer, and a plurality of structural reinforcement members are arranged at intervals in sequence along the length direction of the wrapping film body; a first exhaust channel disposed on the thermal-sensitive layer, and a plurality of first exhaust channels are arranged at intervals in sequence along the length direction of the wrapping film body and extend along the width direction of the wrapping film body; wherein, the first exhaust channel is provided with at least one opening for discharging the gas in the wrapping film body.

[0010] In one preferred embodiment, the utility model provides a technical solution regarding the position, quantity and structural design of the structural reinforcement member on the base material layer.

[0011] In the technical solution of this embodiment, the structural reinforcement member is disposed inside the base material layer; and / or the structural reinforcement member is disposed on the surface of the base material layer.

[0012] Further, at least two rows of structural reinforcement members are provided along the width direction of the wrapping film body, and the structural reinforcement members are arranged in a staggered manner along the length direction of the wrapping film body.

[0013] Further, the structural reinforcement member is of a symmetrical structure, and the distance between two adjacent structural reinforcement members in any row of the structural reinforcement members is equal.

[0014] In another preferred embodiment, the utility model provides a technical solution regarding the specific position design among the first exhaust channel, the second exhaust channel and the structural reinforcement member.

[0015] In the technical solution of this embodiment, the cell wrapping film includes a second exhaust channel disposed on the thermal-sensitive layer. The second exhaust channels are arranged at intervals in sequence along the width direction of the wrapping film body and extend along the length direction of the wrapping film body, and the second exhaust channel is provided with at least one opening.

[0016] Further, the first exhaust channel and the second exhaust channel are arranged in a staggered manner so that they are distributed in a grid pattern, and the grid spaces formed by the structural reinforcement member and the first exhaust channel and the second exhaust channel correspond to each other.

[0017] Further, the cross section of the first exhaust channel and the second exhaust channel is any one or several of a circular shape, an elliptical shape or a rectangular shape.

[0018] In another preferred embodiment, the utility model provides a technical solution regarding the specific material of the structural reinforcement member.

[0019] The elastic modulus of the structural reinforcement member is greater than that of the base material layer, and specifically may be at least one of polyamide, polypropylene or polyethylene.

[0020] In another preferred embodiment, the present utility model provides a technical solution regarding the structural design of the base material layer.

[0021] Among them, the thickness of the wrapping film body is 30 - 80 μm, the thickness of the base material layer is 25 - 60 μm, and the thickness of the thermal-sensitive layer is 1 - 20 μm.

[0022] Furthermore, the base material layer at least includes a CPP layer, a polyolefin layer, and a PP layer, and the CPP layer, the polyolefin layer, and the PP layer are arranged in sequence along the direction close to the thermal-sensitive layer.

[0023] To sum up, compared with the prior art, the cell wrapping film provided by the present utility model has at least the following technical effects:

[0024] 1) The base material layer of the cell wrapping film is provided with a structural reinforcement member having a relatively large elastic modulus, which is used to improve the overall structural strength of the wrapping film, avoid the wrapping film from bending in the natural state and affecting the shelling process, and enable the wrapping film to have high structural performance without increasing the thickness of the film material, thereby avoiding compressing the design space of the cell and reducing the energy density of the cell;

[0025] 2) The thermal-sensitive layer of the cell wrapping film is provided with an exhaust channel, which is used to provide a flow channel for the gas generated during the high-temperature hot pressing process to be discharged, reduce the moving distance when the gas is discharged, thereby facilitating the timely discharge of the bubbles in the wrapping film, improving the overall film surface flatness after the wrapping film wraps the cell, increasing the effective bonding area of the thermal-sensitive layer, optimizing the pasting effect of the wrapping film, and enhancing the bonding and fitting stability between the wrapping film and the cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the interlayer structure of the cell wrapping film of the present utility model;

[0027] Figure 2 is a first schematic diagram of the cell wrapping film of the present utility model projected orthogonally along its thickness direction;

[0028] Figure 3 is a second schematic diagram of the cell wrapping film of the present utility model projected orthogonally along its thickness direction;

[0029] Figure 4 is a third schematic diagram of the cell wrapping film of the present utility model projected orthogonally along its thickness direction.

[0030] Among them, the meanings of the reference numerals are as follows:

[0031] 1. Wrapping film body; 2. Base material layer; 21. CPP layer; 22. Polyolefin layer; 23. PP layer; 3. Thermal-sensitive layer; 4. Structural reinforcement member; 5. First exhaust channel; 6. Second exhaust channel. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] For better understanding and implementation, the technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present utility model.

[0033] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present utility model belongs. The terms used in the description of the present utility model herein are only for the purpose of describing specific embodiments and are not intended to limit the present utility model.

[0035] See Figure 1 As shown, the enhanced easy-exhausting cell wrapping film provided by the present utility model includes a wrapping film body 1, and the wrapping film body 1 includes a base material layer 2 and a thermosensitive layer 3, which are bonded and compounded. Among them, the base material layer 2 is used to improve the stability of the cell wrapping film and play a role in fixing the thermosensitive layer 3. The thermosensitive layer 3 is an adhesive layer for bonding the cell wrapping film to the cell. The thermosensitive layer 3 has no viscosity at normal temperature and has a fast release of viscosity under high temperature conditions, and has the characteristics of sticking when heated and sticking when cooled. During specific operation, the thermosensitive layer 3 is directly contacted with the bare cell, and then the whole contact surface of the thermosensitive layer 3 and the bare cell can be quickly and strongly bonded through a hot press, so that the cell wrapping film is wrapped on the outer surface of the bare cell, preventing the diaphragm from being scratched or punctured by the aluminum shell during the process of putting the bare cell into the shell, and being arranged between the bare cell and the battery housing after being put into the shell, playing a role of insulation protection.

[0036] See Figure 2 As shown, in the technical solution of the present utility model, the base material layer 2 is provided with a plurality of structural reinforcement members 4, and the structural reinforcement members 4 are arranged at intervals in sequence along the length direction of the wrapping film body 1. Among them, the structural reinforcement members 4 are used to improve the overall structural performance of the wrapping film body 1, compensate for the problem of the decrease in the film surface stiffness caused by the reduction of the thickness of the base material layer 2, and avoid the bending of the wrapping film in the natural state, which may affect the process of putting the cell into the shell. And, without increasing the thickness of the film material, the wrapping film has high structural performance, thus solving the technical problem in the prior art that the design space of the compressed cell is reduced and the energy density of the cell is reduced due to the too large thickness of the cell wrapping film.

[0037] When ensuring the structural performance of the cell wrapping film structure by setting the structural reinforcement 4, the thickness of the wrapping film body 1 of the present utility model can be set to 30-80 μm, the thickness of the substrate layer 2 can be set to 25-60 μm, and the thickness of the thermal-sensitive layer 3 can be set to 1-20 μm. Compared with the Mylar film that needs to be thickened in the prior art, etc., the present utility model has significant advantages in terms of thickness setting. Preferably, the thickness of the wrapping film body 1 is set to 60 μm, the thickness of the substrate layer 2 is set to 50 μm, and the thickness of the thermal-sensitive layer 3 is set to 10 μm.

[0038] See Figure 3 As shown, the thermal-sensitive layer 3 of the present utility model is provided with a plurality of first exhaust channels 5, which are arranged at intervals in sequence along the length direction of the wrapping film body 1, and the first exhaust channels 5 extend along the width direction of the wrapping film body 1. Among them, the first exhaust channel 5 is provided with at least one opening for exhausting the gas of the wrapping film body 1 in the width direction of the wrapping film body 1. Specifically, the first exhaust channel 5 is used to provide a flow channel for exhausting the gas (bubbles) generated by the thermal-sensitive layer 3 during the high-temperature hot pressing process, so that the gas is discharged from the opening of the exhaust channel during the hot pressing process, effectively avoiding the molten hot melt adhesive from hindering the gas discharge and reducing the moving distance during the gas discharge, thereby facilitating the timely discharge of the bubbles of the wrapping film. At the same time, since the gas in the wrapping film is discharged in time, a uniform and stable wrapping film layer can be obtained after hot pressing, improving the overall film surface flatness of the cell wrapping film after wrapping the cell, increasing the effective bonding area of the thermal-sensitive layer 3, optimizing the pasting effect of the cell wrapping film, and improving the bonding and fitting stability between the wrapping film and the cell without special treatment processes.

[0039] Preferably, the first exhaust channel 5 provided by the present utility model can be set to have two openings (such as Figure 3 shown), that is, the first exhaust channel 5 extends along the width direction of the wrapping film body 1 and penetrates it. Through the structural design method of two openings, the exhaust rate and exhaust speed of the gas can be further improved, that is, the film surface flatness of the cell wrapping film is further improved.

[0040] Embodiment 1

[0041] See Figure 2 As shown, Embodiment 1 of the present utility model provides a technical solution regarding the position, quantity, and structural design of the structural reinforcement 4 in the substrate layer 2.

[0042] In a preferred solution of this embodiment, the maximum length of the structural reinforcement 4 in the thickness direction of the wrapping film body 1 does not exceed 5 μm, and there are three forms of its position design:

[0043] 1) The structural reinforcement member 4 is disposed inside the base material layer 2. At this time, the height of the structural reinforcement member 4 in the thickness direction of the wrapping film body 1 is not higher than the film surface of the base material layer 2 on the side away from the thermal-sensitive layer 3.

[0044] 2) The structural reinforcement member 4 is disposed on the surface of the base material layer 2. At this time, the structural reinforcement member 4 can extend into the surface of the base material layer 2 to form a flat film surface, reducing the influence on the flatness of the film surface while strengthening the structural strength of the wrapping film body 1; the structural reinforcement member 4 can also protrude from the joint surface between the base material layer 2 and the thermal-sensitive layer 3, thereby strengthening the joint stability between the base material layer 2 and the thermal-sensitive layer 3.

[0045] 3) The structural reinforcement member 4 is disposed inside the base material layer 2 and on the surface of the base material layer 2. At this time, preferably three rows of structural reinforcement members 4 can be disposed in the thickness direction of the wrapping film body 1 (one row is inside the base material layer 2, one row is on the surface of the base material layer 2, and one row is at the joint surface between the base material layer 2 and the thermal-sensitive layer 3). This structural design method is the optimal setting method of the present utility model, and it has the best effect on enhancing the structural performance of the wrapping film body 1.

[0046] See Figure 2 As shown, in another preferred solution of this embodiment, in the width direction of the wrapping film body 1, the base material layer 2 is provided with at least two rows of structural reinforcement members 4, and the structural reinforcement members 4 between each row are arranged staggered with each other in the length direction of the wrapping film body. Among them, by setting at least two rows of structural reinforcement members 4 arranged in a staggered manner, the structural performance of the wrapping film body 1 can be further improved, ensuring that no local bending phenomenon occurs at any position of the wrapping film body 1 in the width direction when it is put into the shell, and improving the efficiency of the battery cell packaging process.

[0047] Furthermore, see Figure 2 As shown, the structural reinforcement member 4 is a symmetric structure, and can be specifically set to any one or several of the structural forms such as star-shaped, cross-shaped, pentagonal, Y-shaped, and circular. And, in any row of the structural reinforcement members 4, the distance between any two adjacent structural reinforcement members 4 is equal, that is, the structural reinforcement members 4 are evenly distributed in the base material layer 2. Through this structural design method, it can be ensured that the structural reinforcement member 4 can provide uniform and stable structural performance for the base material layer 2, and at the same time can improve the overall flatness of the wrapping film body 1 after wrapping the battery cell.

[0048] Embodiment 2

[0049] See Figure 3 and Figure 4 As shown, Embodiment 2 of the present utility model provides a technical solution regarding the position design among the first exhaust passage 5, the second exhaust passage 6, and the structural reinforcement member 4.

[0050] See Figure 3As shown, in the technical solution of this embodiment, the thermal-sensitive layer 3 is further provided with a plurality of second exhaust channels 6. The second exhaust channels 6 are arranged at intervals in sequence along the width direction of the wrapping film body 1 and extend along the length direction of the wrapping film body 1. Similarly, the second exhaust channels 6 are also provided with at least one opening for exhausting the gas of the wrapping film body 1 in the length direction of the wrapping film body 1. Specifically, on the basis of setting the first exhaust channel 5, adding the second exhaust channel 6 can further increase the flow channels for exhausting the gas generated during the high-temperature hot pressing process, so that the gas (bubbles) can be exhausted from the exhaust channels at the openings in the length direction or width direction of the wrapping film body 1 during the hot pressing process, further improving the exhaust rate and exhaust speed of the gas in the wrapping film, that is, further improving the flatness of the film surface of the battery cell wrapping film.

[0051] See Figure 4 As shown, in a preferred solution of this embodiment, the first exhaust channel 5 and the second exhaust channel 6 are arranged in a staggered manner so that the two exhaust channels are distributed in a grid pattern, thereby providing flow channels and discharge ports for the gas in the wrapping film in both the length direction and the width direction of the wrapping film body 1, and improving the exhaust performance of the wrapping film body 1.

[0052] Among them, when viewed along the thickness direction of the wrapping film body 1, the position of the structural reinforcement 4 corresponds to the grid space position formed by the first exhaust channel 5 and the second exhaust channel 6. Specifically, in the thickness direction of the wrapping film body 1, the thickness of the thermal-sensitive layer 3 at the grid space position is greater than the thickness of the two exhaust channel positions (since this is a hollow design here), and the structural reinforcement 4 is used to enhance the structural performance of the base material layer 2, and the base material layer 2 is used to fix the thermal-sensitive layer 3. Therefore, in the present invention, the structural reinforcement 4 is arranged at a position corresponding to the grid space formed by the two exhaust channels, which can enable the base material layer 2 to better provide support and fixation for the thermal-sensitive layer 3.

[0053] In another preferred solution of this embodiment, the cross-sectional shapes and sizes of the first exhaust channel 5 and the second exhaust channel 6 can be adjusted accordingly according to the specific design requirements of different battery models. For example, the cross-sections of the first exhaust channel 5 and the second exhaust channel 6 can be set to any one or several of circular, elliptical or rectangular shapes.

[0054] Embodiment 3

[0055] Embodiment 3 of the present invention provides a technical solution regarding the specific material of the structural reinforcement 4.

[0056] In the technical solution of this embodiment, the structural reinforcement member 4 is made of a material with a relatively large elastic modulus. At least one of polyamide, polypropylene, or polyethylene with an elastic modulus greater than that of the base material layer 2 can be preferentially used. Specifically, in the case of setting a low-thickness wrapping film, by adding the structural reinforcement member 4 with a relatively large elastic modulus to the base material layer 2, the problem of the decrease in the film surface stiffness caused by the reduction in the thickness of the base material layer 2 can be compensated, and the wrapping film can be prevented from bending in the natural state, which may affect the process of inserting it into the shell. Moreover, the structural reinforcement member 4 can endow the wrapping film with high structural performance without increasing the thickness of the film material, thereby solving the technical problems in the prior art that the excessive thickness of the battery cell wrapping film leads to the reduction of the design space for compressing the battery cell and the reduction of the energy density of the battery cell.

[0057] During specific production, the wrapping film can be prepared by processes such as co-extrusion or blown film. Taking the co-extrusion process as an example, materials such as polyamide, polypropylene, or polyethylene with a larger elastic modulus are synchronously set at the position of the extrusion head, and thus the structural reinforcement member 4 can be added to the base material layer 2. Taking the blown film process as an example, materials such as polyamide, polypropylene, or polyethylene with a larger elastic modulus are added when the base material is heated and melted to form a melt flow state, and after cooling and shaping, the base material layer 2 with the added structural reinforcement member 4 can be formed.

[0058] Certainly, the preparation process of the wrapping film is not limited to the above two, and any technical solution that can achieve the addition of the structural reinforcement member 4 to the base material layer 2 is within the protection scope of the present utility model.

[0059] Embodiment 4

[0060] See Figure 1 As shown in the figure, Embodiment 4 of the present utility model provides a technical solution regarding the structural design of the base material layer 2.

[0061] In the technical solution of this embodiment, the base material layer 2 is a multi-layer composite structure, and at least a three-layer composite structure.

[0062] Specifically, as shown in Figure 1 the figure, the base material layer 2 at least includes a CPP (cast polypropylene) layer 21, a polyolefin layer 22, and a PP (polypropylene) layer 23, and the CPP layer 21, the polyolefin layer 22, and the PP layer 23 are arranged in sequence along the direction close to the thermosensitive layer. Among them, the above-mentioned layer structure of the base material layer 2 has good high-temperature resistance, insulation, and bonding properties, and each layer structure can be separately prepared and compounded by processes such as co-extrusion, blown film, and blow molding.

[0063] The technical means disclosed by the solution of the present utility model are not limited to the technical means disclosed in the above embodiments, but also include technical solutions formed by any combination of the above technical features. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present utility model, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present utility model.

Claims

1. A reinforced and easily vented battery cell wrapping film, characterized in that: include: A wrapping film body, wherein the wrapping film body comprises a substrate layer and a heat-sensitive layer; A structural reinforcement member disposed on the substrate layer, wherein a plurality of the structural reinforcement members are sequentially spaced apart along the length direction of the wrapping film body; A first exhaust channel is provided in the heat-sensitive layer, wherein a plurality of the first exhaust channels are sequentially arranged at intervals along the length direction of the wrapping film body and extend along the width direction of the wrapping film body; Wherein, the first exhaust channel is provided with at least one opening for exhausting the gas in the wrapping film body.

2. The enhanced easy-to-exhaust battery cell wrapping film according to claim 1, characterized in that: The structural reinforcement member is disposed inside the substrate layer; And / or the structural reinforcement is arranged on the surface of the substrate layer.

3. The enhanced easy-to-exhaust battery cell wrapping film according to claim 1, characterized in that: At least two rows of the structural reinforcement members are arranged along the width direction of the wrapping film body, and the structural reinforcement members are arranged alternately along the length direction of the wrapping film body.

4. The enhanced easy-to-exhaust battery cell wrapping film according to claim 3, characterized in that: The structural reinforcement members are of symmetrical structure, and the distance between two adjacent structural reinforcement members in any row of the structural reinforcement members is equal.

5. The enhanced easy-to-exhaust battery cell wrapping film according to claim 1, characterized in that: The battery cell wrapping film also includes a second exhaust channel arranged on the thermosensitive layer. The second exhaust channels are arranged in sequence and spaced apart along the width direction of the wrapping film body and extend along the length direction of the wrapping film body. The second exhaust channel has at least one opening.

6. The enhanced easy-to-exhaust battery cell wrapping film according to claim 5, characterized in that: The first exhaust channel and the second exhaust channel are arranged alternately so as to be distributed in a grid shape, and the structural reinforcement corresponds to the grid space formed by the first exhaust channel and the second exhaust channel.

7. The enhanced easy-to-exhaust battery cell wrapping film according to claim 5, characterized in that: The cross-sections of the first exhaust channel and the second exhaust channel are any one or more of circular, elliptical or rectangular.

8. The enhanced easy-to-vent battery cell wrapping film according to any one of claims 1 to 7, characterized in that: The structural reinforcement is at least one of polyamide, polypropylene or polyethylene.

9. The enhanced easy-to-vent battery cell wrapping film according to any one of claims 1 to 7, characterized in that: The thickness of the wrapping film body is 30-80 μm, the thickness of the substrate layer is 25-60 μm, and the thickness of the heat-sensitive layer is 1-20 μm.

10. The enhanced easy-to-vent battery cell wrapping film according to any one of claims 1 to 7, characterized in that: The substrate layer at least includes a CPP layer, a polyolefin layer and a PP layer, and the CPP layer, the polyolefin layer and the PP layer are arranged in sequence along a direction close to the heat-sensitive layer.

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