Polyester film for coating lithium battery core

Abstract

The utility model provides a polyester film for coating a lithium battery core, which relates to the technical field of lithium batteries and comprises a bottom film, a side large film, a connecting area and an extension section, wherein the surface of the bottom film is provided with a plurality of through-hole-shaped air holes, the side large film is arranged on two sides of the bottom film and is integrated with the bottom film, and the connecting area and the extension section are arranged on two sides of the side large film and are integrated with the other two sides of the bottom film. An adhesion area is arranged in the extension section, the adhesion area is adhered to the connecting area, at least part of the outer surface of the extension section is a rough surface, creases are arranged at the connecting position of the bottom film and the side large film and the connecting position of the bottom film and the extension section, and the outward expanding length of the extension section does not exceed the length of the extension section. The connection friction force between the connection area and the adhesion area can be increased through the rough surface, so that the connection area and the adhesion area are not easy to separate, the adhesion strength is improved, as the extension section and the connection area are cut, a part of materials can be saved, the protection of the naked battery cell is not influenced while the cost is reduced, and the structure is particularly suitable for mass production.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, and more specifically, to a polyester film for coating lithium battery cells. Background Technology

[0002] Traditionally, bare battery cells are wrapped with a polyester film, commonly known as Mylar, when they are installed in a casing. After Mylar covers the bare battery cell, there is a certain gap at the rounded corners of the bare battery cell. The corners of the bare battery cell are prone to scratching against the inner wall of the aluminum casing. This poses a risk of contact between the electrode and the aluminum casing, which can lead to electrical contact between the negative electrode and the aluminum casing, causing adverse reactions such as casing corrosion and leakage. This can result in a decrease in battery insulation performance, performance degradation, and may even lead to safety risks.

[0003] Therefore, we propose a method to completely encapsulate the bare battery cell with Mylar to prevent electrical contact between the negative electrode and the aluminum casing, while improving the safety and reliability of the battery product. Utility Model Content

[0004] The technical problem to be solved by this utility model is that after Mylar coats the bare battery cell, there is a certain space gap at the R-corner position of the bare battery cell, which may cause safety risks. In view of the problems existing in the prior art, a polyester film for coating lithium battery cells is provided.

[0005] The purpose and effect of this utility model are achieved by the following specific technical means: a polyester film for coating lithium battery cells, comprising:

[0006] The bottom film has several through-hole-like pores on its surface;

[0007] Side membranes are disposed on both sides of the bottom membrane and are integrated therewith, and connecting areas are provided on both sides of the side membranes;

[0008] An extension section is provided on both sides of the bottom film and is integrated with it. The extension section is provided with an adhesive area, which is adhered to the connecting area. At least part of the outer surface of the extension section is a rough surface.

[0009] This design, through the extension section and the large side film, can provide good protection for the outside of the bare cell, and the rough surface can make the connection between the adhesive area and the connection area tighter.

[0010] A further preferred embodiment: creases are provided at the connection points between the bottom film and the side film, as well as at the connection points between the bottom film and the extension section;

[0011] This design allows the side and bottom films to be folded and wrapped around the bare battery cell, and the creases can be positioned to correspond to the radius (R) of the bare battery cell.

[0012] A further preferred embodiment: the outward extension length of the extension segment does not exceed the length of the extension segment itself;

[0013] The length of the extended section extending outward is preferably equal to the length of the side membrane extending outward.

[0014] A further preferred embodiment: the side membrane and the extended section, when folded and erected, together with the bottom membrane, form a rectangular body with an open top.

[0015] The connecting area folds onto the outer surface of the extension section and adheres to the adhesive area to form an overlapping area.

[0016] A further preferred embodiment: the entire outer surface of the extension section or only the outer surface of the adhesive area is a rough surface, and the overlapping area corresponds to the rough surface.

[0017] A further preferred embodiment: the adhesive area is located at both ends of the extension section, or is arranged in multiple intervals within the extension section.

[0018] The beneficial effects of this utility model are:

[0019] When the adhesion requirements are high, the adhesion area can be the outer surface of the entire extension section. The outward extension length of the extension section is equal to the outward extension length of the side membrane. After the extension section and the side membrane are folded and erected, the connection area is folded towards the extension section. The connection areas on the same side of the two side membranes cover the extension section, each occupying half of the area of ​​the extension section. Then the two connection areas just wrap the outer wall of the extension section. The connection area is then glued to the outer wall of the extension section using adhesive. This method has the largest adhesion area and the highest adhesion strength, which can effectively protect the outer wall of the bare cell from scratching the aluminum shell.

[0020] The rough surface increases the friction between the connection area and the adhesive area, making it less likely to separate and improving the adhesion strength. Because the extension section and the connection area are cut off, some materials can be saved, reducing costs without affecting the protection of the bare cell, which is especially suitable for mass production. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings.

[0022] Figure 1 This is a top view of the overall structure of this utility model;

[0023] Figure 2 This is a top view of the overall structure of this utility model;

[0024] Figure 3 This utility model Figure 2 A three-dimensional diagram of the overall structure;

[0025] Figure 4 This is a schematic diagram of the overall structure of this utility model;

[0026] Figure 5 This is a schematic diagram of the overall structure of this utility model;

[0027] Figure 6 This utility model Figure 1 A schematic diagram of the overall structure (with the battery cell enclosed);

[0028] Figure 7 This utility model Figure 4 A schematic diagram of the overall structure (with the battery cell enclosed);

[0029] Figure 8 This is a schematic diagram of the layered structure of the extension section of this utility model.

[0030] Figures 1-8 Middle: bottom membrane (1), pores (101), side membrane (2), connecting area (201), extension section (3), adhesive area (301), overlapping area (4). Detailed Implementation

[0031] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are merely examples for implementing this utility model. It must be pointed out that the disclosed embodiments do not limit the scope of this utility model. On the contrary, any modifications and refinements made without departing from the scope of this utility model are within the patent protection scope of this utility model.

[0032] Please see Figures 1-8 A polyester film for coating lithium battery cells, comprising:

[0033] The bottom film 1 has several through-hole-shaped pores 101 on its surface. When wrapping the battery cell, the bottom film 1 corresponds to the bottom of the bare battery cell (e.g., Figure 3 As shown in the figure, the arrangement of pores 101 facilitates the penetration of electrolyte into the electrode.

[0034] The side membrane 2 is disposed on both sides of the bottom membrane 1 and is integral with it. The side membrane 2 has connecting areas 201 on both sides. When wrapping the battery cell, the side membrane 2 corresponds to the large end face of the bare battery cell (e.g., Figure 3 (as shown)

[0035] Extension section 3 is disposed on both sides of the bottom film 1 and is integrated with it. When wrapping the battery cell, extension section 3 corresponds to the small end face of the bare battery cell (e.g., Figure 3 (as shown)

[0036] Preferably, creases are provided at the connection points between the bottom film 1 and the side film 2, as well as between the bottom film 1 and the extension section 3. Since the corner of the bare cell is an arc-shaped R-angle, one or two creases can be provided. When there are two creases, the two creases correspond to the beginning and end of the arc-shaped R-angle of the bare cell, respectively. The side film 2 and the extension section 3 can be precisely bent through the creases, so that the side film 2 and the extension section 3 are folded more precisely outside the bare cell. The bottom film 1 just covers the bottom surface of the bare cell. When the side film 2 and the extension section 3 are folded and upright, they form a rectangular body with a top opening with the bottom film 1, which wraps around the outer wall of the bare cell. The top opening is reserved for the position of the top cover of the cell, which is convenient for later assembly with the aluminum shell.

[0037] Please see Figures 1-5 The extension section 3 is provided with an adhesive area 301, which is adhered to the connecting area 201, and at least part of the outer surface of the extension section 3 is a rough surface.

[0038] Preferred, such as Figure 3 As shown, when the adhesion requirement is high, the adhesion area 301 can be the outer surface of the entire extension section 3. The outward extension length of the extension section 3 is equal to the outward extension length of the side large film 2. After the extension section 3 and the side large film 2 are folded and erected, the connection area 201 is folded towards the extension section 3. The connection areas 201 on the same side of the two side large films 2 cover the extension section 3, each occupying half of the area of ​​the extension section 3. Then the two connection areas 201 just wrap the outer wall of the extension section 3. The connection area 201 is glued to the outer wall of the extension section 3 using adhesive. This method has the largest adhesion area and the highest adhesion strength, which can effectively protect the outer wall of the bare cell from scratching the aluminum shell.

[0039] Preferred, such as Figure 4 , Figure 5 As shown, to reduce material costs, this application also provides another embodiment, in which the extension section 3 is processed into a narrower shape, with a width half the width of the bare cell side surface, and the adhesive area 301 is processed into a wider shape and disposed at both ends of the extension section 3, such as an I-shape (e.g., Figure 4 (As shown), or multiple adhesive areas 301 can be set, and the multiple adhesive areas 301 can be set in multiple segments at intervals in the extension section 3 (such as...). Figure 5 As shown), the outer end of the connecting area 201 is also cut with an outward protrusion corresponding to the adhesive area 301. When the extension section 3 and the side large film 2 are folded to wrap the bare cell, the connecting area 201 is folded over the adhesive area 301, and the two will overlap and correspond to each other (as shown). Figure 7As shown), if the extension section 3 and the adhesive area 301 are in an I-shape, then the connection area 201 on the same side of the two large side films 2 and the adhesive area 301 will form a four-point bond, forming a rectangular four-point overlapping area 4, which can ensure the strength of the bond. At the same time, because the entire outer surface of the extension section 3 or only the outer surface of the adhesive area 301 is a rough surface, and the overlapping area 4 corresponds to the rough surface, the friction between the connection area 201 and the adhesive area 301 can be increased through the rough surface, making it more difficult to separate and improving the bond strength. Because the extension section 3 and the connection area 201 are cut, some materials can be saved, achieving cost reduction without affecting the protection of the bare cell, which is especially suitable for mass production.

[0040] Preferred, such as Figure 1 , Figure 6 Regarding cost reduction of materials, this application also provides another implementation method, in which the length of the extension section 3 is set to 3cm, the extension section 3 is folded to wrap around the bottom R-corner of the bare cell, and the two connection areas 201 are folded to overlap and stick together. The two connection areas 201 extend to the small end face of the bare cell to protect it, which can also achieve the same protective effect, save the material of the extension section 3, and also achieve the same cost reduction effect.

Claims

1. A polyester film for coating lithium battery cells, characterized in that, include: The bottom film has several through-hole-like pores on its surface; Side membranes are disposed on both sides of the bottom membrane and are integrated therewith, and connecting areas are provided on both sides of the side membranes; An extension section is disposed on both sides of the bottom film and integrated therewith. The extension section is provided with an adhesive area, which is adhered to the connecting area, and at least part of the outer surface of the extension section is a rough surface.

2. The polyester film for coating lithium battery cells according to claim 1, characterized in that: Creases are provided at the connection points between the bottom membrane and the side membrane, as well as between the bottom membrane and the extension section.

3. The polyester film for coating lithium battery cells according to claim 1, characterized in that: The outward extension of the extension segment does not exceed the length of the extension segment itself.

4. The polyester film for coating lithium battery cells according to claim 1, characterized in that: When the side membrane and the extended section are folded and erected, they together with the bottom membrane form a rectangular body with an open top. The connecting area folds onto the outer surface of the extension section and adheres to the adhesive area to form an overlapping area.

5. The polyester film for coating lithium battery cells according to claim 4, characterized in that: The entire outer surface of the extension section or only the outer surface of the adhesive area is rough, and the overlapping area corresponds to the rough surface.

6. The polyester film for coating lithium battery cells according to claim 5, characterized in that: The adhesive area is located at both ends of the extension section, or is arranged in multiple intervals within the extension section.

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