Battery cell protection film, battery cell, and battery module

Abstract

The utility model discloses a kind of cell protective films, for cladding cell, comprising: film body, for the outer surface of adhering cladding cell;Multiple score, extend along the length direction of film body, multiple score interval distribution along the width direction of film body, film body can be folded from score place;Notch portion, located at both ends of each score, from the edge of film body inwardly recessed along length direction, notch portion includes: first notch, from the edge of film body inwardly recessed;Second notch, from the side of first notch away from the edge of film body continue inwardly recessed;Wherein, the area of second notch is less than the area of first notch, and the edge of first notch and the edge of second notch are connected to form stepped profile.Can prevent four corner places after edge hot melting to form sharp protrusion and shell scratch to cause cell damage by first notch and second notch.The utility model further discloses a kind of cell and a kind of battery module.

Description

Technical Field

[0001] This utility model relates to the field of batteries, and in particular to a cell protective film, a cell, and a battery module. Background Technology

[0002] In recent years, the global new energy vehicle industry has entered a phase of explosive growth. Consumer acceptance and market penetration of new energy vehicles have continued to rise, directly driving exponential growth in market demand for power batteries (mainly lithium batteries). Against this backdrop, market competition in the new energy vehicle and power battery industries has become increasingly fierce. In order to seize market share, companies have entered a stage of competition centered on cost control and efficiency improvement. Especially in the lithium battery field, cost and yield have become key factors determining a company's core competitiveness.

[0003] The manufacturing process of lithium batteries is complex, involving multiple key steps such as slurry preparation, electrode manufacturing, stacking assembly, cell packaging, and liquid injection formation. These steps are highly interconnected; a problem in any one step can not only lead to the scrapping of products from that step but may also render all previous steps futile, directly lowering the overall production yield. Among these, the cell assembly process involves three core steps: stacking and wrapping, cell insertion, and peripheral welding. Yield control in this process is particularly critical. In traditional processes, referencing... Figure 2 (melting point) Figure 2 (Illustration of three solid rectangles within a dashed rectangle), using, as... Figure 1 The cell protective film 01 shown covers the cell 07, as follows: Figure 3 As shown, after the coating is hot-melted, sharp protrusions are easily formed at the corners, which can cause scratches when inserting into the casing and thus damage the battery cell. In the subsequent peripheral welding process, defects such as glue jamming and explosion points may occur due to the deformation and protrusion of the coating material. These problems not only lead to a lot of rework and scrap, but also increase labor and material costs.

[0004] Given the current state of the industry, there is an urgent need for a technical solution that can optimize the stacking and coating effect, improve the yield of cell insertion and peripheral welding, reduce defect losses from the manufacturing process, lower production costs, and meet the urgent needs of the new energy vehicle industry for high-yield and low-cost lithium batteries. Utility Model Content

[0005] To address the aforementioned technical problems, this utility model discloses a cell protective film for coating battery cells, comprising:

[0006] The membrane body is used to adhere to and coat the outer surface of the battery cell;

[0007] Multiple grooves extend along the length of the membrane body and are spaced apart along the width of the membrane body. The membrane body can be folded from the grooves.

[0008] The notch, located at both ends of each notch, is recessed inward along the length of the membrane body from the edge. The notch includes:

[0009] The first gap is recessed inward from the edge of the membrane body;

[0010] The second gap continues to be recessed inward from the side of the first gap away from the edge of the membrane body;

[0011] The area of ​​the second gap is smaller than that of the first gap, and the edges of the first gap and the second gap are connected to form a stepped outline.

[0012] By adopting the above technical solution, the second notch can prevent sharp protrusions from forming at the four corners after the edge is folded and heat-melted, avoiding damage to the battery cell or glue jamming around the weld after insertion into the casing. The first notch provides extension space for the edge protective film to extend due to deformation caused by heat melting, further preventing damage to the battery cell or glue jamming. At the same time, the gradient design of the first and second notches can ensure the strength at the notch.

[0013] Optionally, the stepped contour includes a first arc group, a platform segment, and a second arc group connected in sequence. The first arc group and the second arc group each include multiple arc segments connected in sequence. Each arc segment is a part of an independent circle, and the two independent circles corresponding to two adjacent arc segments are externally tangent.

[0014] Optionally, along the extending directions of the first arc group, the platform segment, and the second arc group, the stepped profile exhibits a trend of first rising, then leveling off, and then falling.

[0015] Optionally, the length of the first notch is 7-10 mm along the width direction, and / or the length of the second notch is 4-5 mm along the width direction.

[0016] Optionally, the recess depth of both the first notch and the second notch is 1.5-2.5 mm.

[0017] Optionally, the length of the membrane body is 500-620 mm, and / or the width of the membrane body is 280-320 mm.

[0018] Optionally, the cell protective film includes four grooves spaced apart in sequence. The film body is divided into a first film, a second film, a third film, a fourth film, and a fifth film connected in sequence by the four grooves. The width of the first film and the fifth film is 10-18 mm, and / or the width of the second film and the fourth film is 110-130 mm, and / or the width of the third film is 15-22 mm.

[0019] Optionally, the depth of each of the aforementioned grooves is 0.02-0.04 mm.

[0020] The present invention also discloses a battery cell, wherein the battery cell is covered by the aforementioned battery cell protective film.

[0021] By adopting the above technical solutions, the quality of the battery cells is guaranteed, stability is improved, yield is increased, and manufacturing costs are reduced.

[0022] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a battery module including the above-mentioned battery cell.

[0023] By adopting the above technical solution, a low-cost and highly stable battery module can be obtained. Attached Figure Description

[0024] Figure 1 A schematic diagram showing the flat structure of the cell protective film in a traditional process is provided.

[0025] Figure 2 This diagram illustrates the relative positions of a portion of the protective film on the battery cell and a portion of the hot-melt points during the coating process in traditional manufacturing.

[0026] Figure 3 Show Figure 2 Enlarged schematic diagram of part A after coating;

[0027] Figure 4 This diagram shows a schematic of the flat structure of the battery cell protective film in one embodiment of the present invention.

[0028] Figure 5 This diagram shows a structural schematic of a notch portion in one embodiment of the present invention;

[0029] Figure 6 This diagram illustrates the structure of multiple arc segments in a stepped contour according to one embodiment of the present invention.

[0030] Figure 7 This diagram illustrates the relative position of a notch in the protective film of the battery cell and a portion of the hot-melt point during the coating process in one embodiment of the present invention.

[0031] Figure 8 Show Figure 7 Enlarged schematic diagram of part B after coating.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Cell protective film, 2. Film body, 3. Scratches, 4. Notch, 5. First notch, 6. Second notch, 7. Cell, 8. Plateau segment. Detailed Implementation

[0034] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Although the description of this utility model will be presented in conjunction with preferred embodiments, this does not mean that the features of this utility model are limited to this embodiment. On the contrary, the purpose of describing the utility model in conjunction with the embodiments is to cover other options or modifications that may be derived based on the claims of this utility model. To provide a deep understanding of this utility model, many specific details will be included in the following description. This utility model may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of this utility model, some specific details will be omitted in the description. It should be noted that, without conflict, the embodiments and features in the embodiments of this utility model can be combined with each other.

[0035] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] The terms “first”, “second”, etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0037] In the description of this embodiment, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment based on the specific circumstances.

[0038] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0039] like Figure 4 As shown, and refer to Figure 5 The first aspect of this utility model discloses a cell protective film 1, used to cover the cell ( Figure 4 and Figure 5 (not shown in the image), including:

[0040] Membrane body 2 is used to adhere to the outer surface of the battery cell;

[0041] Multiple scratches Figure 4 Only one of the grooves 3 is indicated in the image, along the length of the membrane body 2 (e.g., ...). Figure 4As shown in direction C), multiple grooves extend along the width direction of the membrane body 2 (e.g., ...). Figure 4 As shown in the diagram, the membrane body 2 is spaced out in direction D, and can be folded from the grooves to cover the battery cell;

[0042] Notch ( Figure 4 Only one notch 4 is indicated in the middle, located at both ends of each notch, and is recessed inward along the length direction from the edge of the membrane body 2.

[0043] The notch includes:

[0044] The first notch 5 is recessed inward from the edge of the membrane body 2;

[0045] The second notch 6 is recessed inward from the side of the first notch 5 away from the edge of the membrane body 2. Furthermore, the area of ​​the second notch 6 is smaller than the area of ​​the first notch 5, and the edges of the first notch 5 and the edges of the second notch 6 connect to form a stepped profile.

[0046] In this invention, each notch has a notch at both ends. One notch corresponds to two notches, two notches correspond to four notches, and so on. Each notch is not a regular shape, but an irregular shape formed by the first notch 5 and the second notch 6. The edges of the first notch 5 and the second notch 6 connect to form a stepped contour. Specifically, the notch as a whole can be an axially symmetrical structure, which can be regarded as two frustums / cylinders of different sizes stacked together, with the top surface area of ​​the lower frustum / cylinder being larger than the bottom surface area of ​​the upper frustum / cylinder. The edges of the longitudinal sections of these two frustums / cylinders form a stepped contour. In other words, the width of the notch changes non-gradually along the concave direction. Figure 7 As shown, the battery cell 7 is covered by a protective film 1. The first notch 5 and the second notch 6 correspond to the hot melting point (the hot melting point is expressed as follows). Figure 7 (Illustration of three solid rectangles within a dashed rectangle, see reference) Figure 8In this scenario, the second notch 6 directly prevents sharp protrusions at the corners of the battery cell during hot-melt folding, preventing scratches on the cell surface during casing insertion that could lead to rework or scrapping, and also preventing weld spalling caused by adhesive inclusions during surrounding welding. The first notch 5, with its larger area, further provides extension space for the hot-melt deformation of the edge film, eliminating cell damage caused by film deformation, while also reducing adhesive inclusions during surrounding welding and preventing weld spalling. The first notch 5 and the second notch 6 reduce production costs, improve production efficiency and yield, and ensure the quality of subsequent products. Under this solution, the flatness of the battery cell coating is better, the first-time defect rate of coating insertion is reduced to 0.01%, and the first-time defect rate of weld spalling caused by the battery cell protective film is reduced to 0.3%, significantly reducing manufacturing costs. Furthermore, compared to directly forming regular structural gaps, such as directly forming U-shaped gaps, the gradient setting of the first gap 5 and the second gap 6 can improve the strength of the membrane at the gap, make the stress evenly distributed, avoid the membrane cracking caused by local stress concentration, improve the tear resistance of the gap edge, reduce the risk of membrane damage during folding, transportation and heat melting, and extend the effective protection period of the protective film.

[0047] In one specific embodiment of this utility model, the first notch 5 and the second notch 6 are connected by a transition. The first notch 5 transitions smoothly to the edge of the membrane, and the corner of the edge of the second notch 6 also transitions smoothly, for example, it can be a rounded transition or a chamfered transition, further improving the overall strength of the notch portion.

[0048] In a specific embodiment of this utility model, reference is made to... Figure 6 The stepped contour includes a first group of circular arcs, a platform segment, and a second group of circular arcs connected in sequence. Each of the first and second groups of circular arcs comprises multiple segments of circular arcs connected in sequence. Each segment is a part of an independent circle, and the two independent circles corresponding to adjacent segments of circular arcs are externally tangent. Figure 6 For example, the first arc group includes four arcs arranged in sequence, with the centers of the independent circles constituting each arc represented by O1, O2, O3, and O4, and the radii of the independent circles represented by R1, R2, R3, and R4; the second arc group includes four arcs arranged in sequence, with the centers of the independent circles constituting each arc represented by O5, O6, O7, and O8, and the radii of the independent circles represented by R5, R6, R7, and R8. Preferably, the first and second arc groups are axially symmetrically distributed; the platform segment 8 is between the first and second arc groups and can be a line segment or a relatively gentle arc segment, preferably a line segment. The stepped contour formed by multiple circumscribed arcs can evenly distribute stress along the entire notch edge, significantly reducing the film breakage rate during the process. The smooth edge without sharp corners or steps is also less likely to snag onto the grippers or conveyor rollers of automated wrapping equipment, improving production efficiency.

[0049] In a specific embodiment of this utility model, reference is made to... Figure 6 Along the extension direction of the first arc group, the platform segment 8, and the second arc group, the stepped contour shows a trend of first rising, then leveling off, and then falling. This can fully match the structure of the cell protection film 1, ensuring that the function of the notch is fully realized and that the strength of the notch is guaranteed.

[0050] In a specific embodiment of this utility model, the length of the first notch 5 is 7-10mm. This size is compatible with multiple arc segments, which can not only disperse the folding and hot-melting stress and improve the tear resistance of the membrane material, but also provide sufficient space for deformation to prevent corner protrusions, reduce the scratches during casing insertion and welding adhesive, and at the same time adapt to automated equipment and multiple specifications of battery cells, thereby improving the encapsulation efficiency.

[0051] In a specific embodiment of this utility model, the length of the second notch 6 along the width direction is 4-5mm. This arrangement can prevent the formation of corner protrusions and fully cooperate with the first notch 5 to play a role, resulting in good mechanical properties.

[0052] In a specific embodiment of this utility model, the recess depth of the first notch 5 and the second notch 6 is 1.5-2.5mm, that is, the total recess depth of a recessed part from the edge of the film body 2 is 3-5mm, which will not affect the protective film from performing its function, and can prevent corner protrusions and fully improve the hot melt stability.

[0053] In one specific embodiment of this utility model, the length of the membrane body 2 is 500-620mm.

[0054] In one specific embodiment of this utility model, the width of the membrane body 2 is 280-320mm.

[0055] In a specific embodiment of this utility model, reference is made to... Figure 1 The battery cell protective film 1 includes four grooves spaced apart in sequence. The film body 2 is divided by the four grooves into a first film M1, a second film M2, a third film M3, a fourth film M4, and a fifth film M5, which are connected in sequence. Specifically, the width of the first film M1 and the fifth film M5 is 10-18 mm. Specifically, the width of the second film and the fourth film is 110-130 mm. Specifically, the width of the third film is 15-22 mm.

[0056] With the above settings, the diaphragm size enables precise coating of each area of ​​the battery cell, avoiding local coating that is too tight or too loose. It works in conjunction with the design of the notch to improve the overall coating adaptability and solve the problem of local process defects. At the same time, it is compatible with automated equipment, effectively improving the battery cell production yield and protection reliability.

[0057] Specifically, the notch is made by a stamping process.

[0058] Specifically, the cell protective film is a polyester film, that is, a Mylar film.

[0059] The second aspect of this utility model discloses a battery cell, which is covered by the battery cell protective film described in the above embodiments. This ensures the quality of the battery cell, improves its stability, increases yield, and reduces manufacturing costs.

[0060] The third aspect of this utility model discloses a battery module, including a battery cell covered by the cell protection film described in the above embodiments, which can obtain a low-cost and high-stability battery module.

[0061] Although the present invention has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above description is a further detailed explanation of the present invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the present invention to these descriptions. Those skilled in the art can make various changes in form and detail, including some simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Images