Battery cell and battery cell packaging method

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a battery cell packaging method. The battery cell comprises a pole group which comprises a pole group body and a pole lug; the packaging film structure comprises a first packaging film and a second packaging film which are buckled with each other, at least one of the first packaging film and the second packaging film is provided with a pit, and the pit is suitable for accommodating the pole group body; the adhesive tape is arranged between the first packaging film and the second packaging film, the adhesive tape and the pit are arranged at intervals, and the packaging film structure is suitable for heat sealing at the position corresponding to the adhesive tape. The adhesive tape is additionally arranged between the first packaging film and the second packaging film, and the position where the adhesive tape is located is the heat sealing position of the packaging film structure, so that in the heat sealing process of the battery cell, sufficient bonding substances can be provided after the adhesive tape is melted, the thickness of a final sealing strip can be increased, and the packaging strength is improved; the problem of insufficient sealing strength caused by thin thickness of the heat sealing layer is solved, the cost can be saved, the weight of the battery cell is reduced, and the energy density of the battery cell is favorably improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to battery cells and battery cell packaging methods. Background Technology

[0002] A battery cell mainly consists of electrode groups and an encapsulation film wrapped around the electrode groups. The encapsulation film has a PP (Polypropylene) layer. During battery cell encapsulation, the end cap heats the encapsulation film, causing the PP layer to melt. After the end cap is removed, the PP layer cools and solidifies to form a uniform phase, thus bonding the two aluminum-plastic films together to achieve a seal. However, because the PP layer is usually relatively thin, it is more prone to over-sealing. After heat melting, the overall thickness of the PP adhesive layer is relatively thin, resulting in low sealing strength and insufficient encapsulation strength. The encapsulation is prone to delamination, failing to effectively prevent external air from entering the battery cell, seriously affecting the safety of the battery cell. Summary of the Invention

[0003] In view of this, the present invention provides a battery cell and a battery cell packaging method to solve the problem of insufficient battery cell packaging strength.

[0004] In a first aspect, the present invention provides a battery cell, comprising: an electrode assembly including an electrode assembly body and electrode tabs; an encapsulation film structure including a first encapsulation film and a second encapsulation film that are interlocked, wherein at least one of the first encapsulation film and the second encapsulation film has a recess, the recess being adapted to accommodate the electrode assembly body; and an adhesive strip disposed between the first encapsulation film and the second encapsulation film and spaced apart from the recess, wherein the encapsulation film structure is adapted to be heat-sealed at a position corresponding to the adhesive strip.

[0005] Beneficial effects: By adding an adhesive strip between the first and second encapsulation films, with the strip located at the heat-sealing position of the encapsulation film structure, the melted adhesive strip provides sufficient adhesive material during the heat-sealing process of the battery cell. This increases the thickness of the final sealing strip, thereby increasing the encapsulation strength and solving the problem of insufficient sealing strength due to a thin heat-sealing layer. Furthermore, it does not affect the thickness of the encapsulation film at other locations of the encapsulation film structure. Compared to the traditional method of increasing the thickness of the heat-sealing layer of the entire encapsulation film structure, this method effectively saves costs, reduces battery cell weight, and helps improve the energy density of the battery cell.

[0006] In one alternative embodiment, the adhesive strip is arranged circumferentially around the recess.

[0007] Beneficial effects: By setting the adhesive strip around the circumference of the recess, it can be ensured that the four sides of the encapsulation film structure can be effectively heat-sealed, thereby improving the encapsulation reliability and sealing performance of the entire cell.

[0008] In one optional embodiment, the adhesive strip includes a first adhesive strip and a second adhesive strip disposed on both sides of the recess along the X direction, and a third adhesive strip and a fourth adhesive strip disposed on both sides of the recess along the Y direction.

[0009] Beneficial effects: By setting four adhesive strips corresponding to the four sides of the recess, all adhesive strips can be arranged around the circumference of the recess, and each adhesive strip can be assembled and positioned with the encapsulation film, which is convenient for operation and helps to improve production efficiency.

[0010] In one optional embodiment, at least a portion of the tab is located between the first encapsulation film and the second encapsulation film, and at least a portion extends out of the encapsulation film structure; the adhesive strip extends along the X or Y direction, and in the direction perpendicular to the extension of the adhesive strip, the distance between the adhesive strip corresponding to the tab and the edge of the recess is A, and the distance between the adhesive strip not corresponding to the tab and the edge of the recess is B, wherein A is greater than B.

[0011] Beneficial effects: By setting the distance A between the adhesive strip corresponding to the tab and the edge of the recess to be greater than the distance B between the adhesive strip not corresponding to the tab and the edge of the recess, it is possible to better adapt to the encapsulation requirements of the encapsulation film structure at different positions, ensuring that the adhesive strip can be set close to the edge of the encapsulation film structure, improving the reliability and stability of the encapsulation, while avoiding excessively large adhesive strip width and unnecessary material waste.

[0012] In one optional implementation, the value of A is in the range of 8 mm ≤ A ≤ 11 mm; and / or, the value of B is in the range of 3 mm ≤ B ≤ 6 mm.

[0013] Beneficial effects: By limiting A to a value between 8 mm and 11 mm, waste of adhesive strip material and increased weight can be avoided, which is conducive to improving the energy density of the battery cell. At the same time, the sealing strength can be guaranteed, improving the sealing and safety of the battery cell. And / or, by limiting B to a value between 3 mm and 6 mm, a reasonable distance between the adhesive strip and the side of the recess can be ensured. This can avoid interference between the packaging and the recess, facilitate the smooth progress of the packaging process, ensure the pass rate of the battery cell, and also ensure the sealing strength, improving the sealing and safety of the battery cell.

[0014] In one optional embodiment, the distance between the adhesive strip and the edge of the encapsulation film structure along the X or Y direction is C, wherein the value of C ranges from 1 mm to 2 mm.

[0015] Beneficial effects: By limiting C to a value between 1 mm and 2 mm, it can be ensured that the adhesive after the adhesive strip is heated can effectively cover the side edges of the encapsulation film structure, protect the aluminum layer, reduce the risk of short circuit, and avoid excessive adhesive overflow that would affect the dimensional accuracy and assembly effect of the battery cell. It also ensures that enough adhesive remains between the first and second encapsulation films, thereby ensuring the encapsulation strength.

[0016] In one optional embodiment, the width of the adhesive strip along the X or Y direction is W, wherein the value of W is in the range of 3 mm ≤ W ≤ 10 mm. And / or, the thickness of the adhesive strip along the Z direction ranges from 100 μm to 500 μm.

[0017] Beneficial effects: By limiting W to a value between 3 mm and 10 mm, it is possible to ensure that the adhesive strip forms a sufficiently thick adhesive layer after heat sealing to enhance the sealing strength, while avoiding material waste and heat sealing defects, thereby improving the overall performance and safety of the battery cell. And / or, by limiting the thickness of the adhesive strip along the Z direction to between 100 μm and 500 μm, it is possible to ensure that the adhesive strip forms a sufficiently thick adhesive layer after heat sealing to enhance the encapsulation strength, while avoiding material waste and heat sealing defects, and protecting the electrode assembly inside the cell from pressure, thereby improving the overall performance and safety of the cell.

[0018] Secondly, the present invention also provides a cell packaging method, the cell packaging method being used to manufacture the aforementioned cell, the cell packaging method comprising: The aluminum-plastic film is perforated and cut to obtain a semi-finished encapsulation film, which includes a first film and a second film, with recesses formed on the first film and / or the second film. An adhesive strip is preheated and pressed to a predetermined position on the first film or the second film. An electrode assembly is placed in the recess, and the first film and the second film are fastened together. The position on the semi-finished encapsulation film corresponding to the adhesive strip is a sealing area. The semi-finished encapsulation film is first encapsulated along the sealing area to press the sealing area to a first predetermined thickness. The battery cell is then injected with electrolyte, formed, and vented. Excess edges on the semi-finished encapsulation film are trimmed to obtain an encapsulation film structure. The encapsulation film structure is second encapsulated along the sealing area to press the sealing area to a second predetermined thickness, wherein the second predetermined thickness is less than the first predetermined thickness. Since the battery cell encapsulation method is used to manufacture the aforementioned battery cell and has the same effect, it will not be elaborated further here.

[0019] In one optional implementation, the first preset thickness is 1.1 to 1.5 times the second preset thickness.

[0020] Beneficial effects: By limiting the first preset thickness to between 1.1 and 1.5 times the second preset thickness, it can ensure that the adhesive fully overflows and seals the aluminum layer during the second encapsulation, improving the safety and reliability of the battery cell, while also ensuring that the seal obtained from the first encapsulation has sufficient strength to prevent battery cell failure.

[0021] In one optional embodiment, the heat sealing temperature used in the second encapsulation process is 180 ℃~210 ℃, the heat sealing pressure is 0.3 MP~0.6 MP, and the heat sealing time is 3 s~5 s.

[0022] Beneficial effects: By increasing the heat sealing temperature and pressure, the adhesive strip can be fully melted, and the melted adhesive strip can provide sufficient adhesive material, thereby forming a high-strength and thick sealing strip, which effectively avoids false sealing. At the same time, during the heat sealing process, the adhesive will overflow and cover the cut surface of the aluminum-plastic film, forming a sealing effect on the aluminum layer, which can effectively reduce the possibility of the aluminum layer of the aluminum-plastic film short-circuiting with the negative electrode through conductive materials. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a top view of an encapsulation film structure before cutting, according to an embodiment of the present invention; Figure 2 for Figure 1 A magnified view of part of E in the diagram; Figure 3 for Figure 1 A magnified view of part of F; Figure 4 This is a schematic diagram of the unfolded structure of the side seal of an encapsulation film structure according to an embodiment of the present invention; Figure 5 for Figure 4 A magnified view of a portion of G; Figure 6 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the aluminum-plastic film structure.

[0025] Explanation of reference numerals in the attached figures: 10. Encapsulation film structure; 101. First encapsulation film; 102. Second encapsulation film; 103. Recess; 104. Cutting line; 11. First preset position; 12. Second preset position; 13. Third preset position; 14. Fourth preset position; 1011. Protective layer; 1012. Aluminum layer; 1013. Heat-sealing layer; 1014. First adhesive layer; 1015. Second adhesive layer; 1016. Nylon layer; 1017. PET layer; 20. Adhesive strip; 30. Tab. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Soft-pack battery cells typically use aluminum-plastic film as the outer casing material. This film is a multi-layered membrane composed of an outer nylon layer, an adhesive, an inner aluminum foil (Al), and an inner heat-sealing layer (PP), forming the outer packaging material for soft-pack batteries. The nylon layer effectively prevents the penetration of oxygen from the air, ensuring a stable internal environment for the cell, while also possessing good deformation elasticity. The aluminum layer effectively blocks the penetration of water molecules from the air, preventing damage to the cell's electrochemical performance. The PP layer, after being heated, acts as an adhesive, bonding the two aluminum-plastic film layers together. Simultaneously, the PP layer has strong chemical stability, preventing direct contact between the internal electrolyte and the aluminum layer, thus preventing corrosion. During cell packaging, the sealing head heats the aluminum-plastic film, melting the PP layer while applying pressure. The two PP layers fuse together, and after the sealing head is removed, the PP layer cools and solidifies to form a uniform phase, thus bonding the two aluminum-plastic film layers together, creating a seal that protects against electrolyte leakage and prevents outside air from entering. Currently, the PP layer in aluminum-plastic film products on the market is generally tens of micrometers in diameter, rarely exceeding 100 μm. Thinner PP layers are more prone to over-sealing. After heat sealing, the overall thickness of the PP adhesive layer is relatively thin, resulting in lower sealing strength and making it easy for the adhesive to come unglued, failing to prevent external air from entering the cell. Simultaneously, an over-sealed PP layer cannot prevent the aluminum layer from contacting the electrolyte, leading to poor edge voltage and edge resistance within the cell. These two points are the main causes of failure in pouch cells. Therefore, it is urgent to find a method to improve the problems of insufficient encapsulation strength due to the thin PP layer and poor edge resistance caused by over-sealing in pouch cells.

[0028] In related technologies, the encapsulation strength is increased by directly thickening the PP layer of the aluminum-plastic film. However, this leads to an increase in the amount of material used in the entire aluminum-plastic film, resulting in increased costs and weight, which reduces the energy density of the battery cell. Furthermore, the PP layer thickness in existing technologies is already sufficient to isolate the electrolyte, so increasing the thickness of the PP layer of the aluminum-plastic film would also cause unnecessary waste.

[0029] The following is combined with Figures 1 to 7 The following describes embodiments of the present invention.

[0030] According to an embodiment of the present invention, a battery cell is provided, comprising: an electrode assembly, an encapsulation film structure 10, and an adhesive strip 20. The electrode assembly includes an electrode assembly body and electrode tabs 30; the encapsulation film structure 10 includes a first encapsulation film 101 and a second encapsulation film 102 that are interlocked, at least one of the first encapsulation film 101 and the second encapsulation film 102 having a recess 103, the recess 103 being adapted to accommodate the electrode assembly body; the adhesive strip 20 is disposed between the first encapsulation film 101 and the second encapsulation film 102 and is spaced apart from the recess 103, the encapsulation film structure 10 being adapted to heat seal at positions corresponding to the adhesive strip 20.

[0031] It should be noted that the encapsulation film structure 10 is made of aluminum-plastic film. The aluminum-plastic film includes a protective layer 1011, an aluminum layer 1012, and a heat-sealing layer 1013 stacked together. The heat-sealing layer 1013 of the first encapsulation film 101 and the heat-sealing layer 1013 of the second encapsulation film 102 are disposed opposite to each other. The material of the heat-sealing layer 1013 is preferably PP.

[0032] The battery cell using this embodiment, by adding an adhesive strip 20 between the first encapsulation film 101 and the second encapsulation film 102, and the location of the adhesive strip 20 being the heat-sealing position of the encapsulation film structure 10, provides sufficient adhesive material after the adhesive strip 20 melts during the heat-sealing process of the battery cell. This increases the thickness of the final sealing strip, thereby increasing the encapsulation strength and solving the problem of insufficient sealing strength due to the thin heat-sealing layer. Furthermore, it does not affect the thickness of the encapsulation film at other positions of the encapsulation film structure 10 besides the encapsulation position. Compared with the traditional method of increasing the thickness of the heat-sealing layer of the entire encapsulation film structure, this method can effectively save costs and reduce the weight of the battery cell, which is beneficial to improving the energy density of the battery cell.

[0033] It should be noted that a battery cell has three perpendicular directions: X, Y, and Z. These directions form a Cartesian coordinate system. The X direction refers to... Figures 1 to 6 The direction indicated by the middle arrow ("X") is the direction of the Y direction. Figures 1 to 6 The direction indicated by the middle arrow (Y) is the same as the direction indicated by the Z arrow (Z). Figures 4 to 6The direction indicated by the middle arrow is "Z". Specifically, the Z direction is the thickness direction of the battery cell. The first encapsulation film 101 and the second encapsulation film 102 are stacked and fastened along the Z direction. The opening of the pit 103 on one encapsulation film faces the other encapsulation film to form a sealed space to accommodate the electrode assembly body.

[0034] It should be noted that the electrode assembly is composed of a positive electrode plate, a negative electrode plate, and a separator located between the positive electrode plate and the negative electrode plate. Optionally, the positive electrode plate, the negative electrode plate, and the separator are all of several layers. The positive electrode plate includes a positive current collector and a positive active material layer coated on the positive current collector. The negative electrode plate includes a negative current collector and a negative active layer coated on the negative current collector. The tab 30 includes a positive tab and a negative tab. The positive tab extends from a portion of the positive current collector, and the negative tab extends from a portion of the negative current collector.

[0035] It should be noted that the first encapsulation film 101 and the second encapsulation film 102 are film sheets. The recess 103 is formed by stamping on the film sheet using a stamping device. Optionally, the recess 103 is stamped on the second encapsulation film 102, and the first encapsulation film 101 is not stamped; or, the recess 103 is stamped on the first encapsulation film 101, and the second encapsulation film 102 is not stamped; or, both the first encapsulation film 101 and the second encapsulation film 102 have recesses stamped on them, and the two recesses are arranged opposite each other to form a receiving space for accommodating the electrode assembly body.

[0036] In one embodiment, the adhesive strip 20 is made of the same material as the heat-sealing layer 1013 of the encapsulation film structure 10, ensuring that the adhesive strip 20 can fuse with the heat-sealing layer 1013 of the encapsulation film structure 10 during the heat-sealing process, increasing the thickness of the heat-sealing layer at the heat-sealing point, thereby increasing the encapsulation strength and solving the problem of insufficient sealing strength due to a thin heat-sealing layer. Preferably, the adhesive strip 20 is made of PP.

[0037] In one embodiment, the adhesive strip 20 is arranged circumferentially around the recess 103. By arranging the adhesive strip 20 circumferentially around the recess 103, effective heat sealing reinforcement can be ensured on all four sides of the encapsulation film structure 10, thereby improving the encapsulation reliability and sealing performance of the entire battery cell.

[0038] In one embodiment, the adhesive strip 20 includes a first adhesive strip and a second adhesive strip disposed on both sides of the recess 103 along the X direction, and a third adhesive strip and a fourth adhesive strip disposed on both sides of the recess 103 along the Y direction. It should be noted that the opening shape of the recess 103 is typically rectangular, and the adhesive strip 20 is elongated. During the cell manufacturing process, the adhesive strip 20 is preheated and pressed onto the first encapsulation film 101 or the second encapsulation film 102 to facilitate subsequent encapsulation of the encapsulation film structure 10. By setting four adhesive strips corresponding to the four sides of the recess 103, all adhesive strips 20 can be arranged circumferentially around the recess 103, and each adhesive strip 20 can be individually assembled and positioned with the encapsulation film, facilitating operation and improving production efficiency.

[0039] In other embodiments, the adhesive strip can also be a single strip, with the entire strip 20 being bent to create a circumference of the recess 103.

[0040] In one embodiment, at least a portion of the tab 30 is located between the first encapsulation film 101 and the second encapsulation film 102, and at least a portion extends out of the encapsulation film structure 10. The adhesive strip 20 extends along the X or Y direction. In the direction perpendicular to the extension of the adhesive strip 20, the distance between the adhesive strip 20 corresponding to the tab 30 and the edge of the recess 103 is A, and the distance between the adhesive strip 20 not corresponding to the tab 30 and the edge of the recess 103 is B, where A is greater than B. It should be noted that the adhesive strip 20 extends along the X or Y direction, and the extension direction of the adhesive strip 20 is parallel to the extension direction of the side of the recess 103 corresponding to it. For the position where the tab 30 is provided, the encapsulation edge of the encapsulation film structure 10 is usually wider, and the distance between the edge of the side of the encapsulation film structure 10 corresponding to the tab 30 and the recess 103 is smaller than the distance between the edge of the side of the encapsulation film structure 10 not having the tab 30 and the recess 103. Therefore, by setting the distance A between the adhesive strip 20 corresponding to the tab 30 and the edge of the recess 103 to be greater than the distance B between the adhesive strip 20 not corresponding to the tab 30 and the edge of the recess 103, it is possible to better adapt to the encapsulation requirements of the encapsulation film structure 10 at different positions, ensure that the adhesive strip 20 can be set close to the edge of the encapsulation film structure 10, improve the reliability and stability of the encapsulation, and at the same time avoid the adhesive strip 20 being too wide, thus avoiding unnecessary material waste.

[0041] It should be noted that A and B are the dimensions when the adhesive strip 20 is pre-pressed and fixed on the encapsulation film. That is, before the battery cell is heat-sealed, in the direction perpendicular to the extension of the adhesive strip 20, the distance between the adhesive strip 20 corresponding to the tab 30 and the edge of the recess 103 is A, and the distance between the adhesive strip 20 not corresponding to the tab 30 and the edge of the recess 103 is B.

[0042] In one embodiment, the value of A is in the range of 8 mm ≤ A ≤ 11 mm. If A is less than 8 mm, the adhesive strip 20 corresponding to the tab 30 is too close to the recess 103. Since the distance between the edge of the side of the encapsulation film structure 10 where the tab 30 is located and the edge of the recess 103 is relatively large, in order to ensure a reasonable distance between the adhesive strip 20 and the edge of the encapsulation film structure 10, the required width of the adhesive strip 20 is relatively wide, resulting in material waste and increased weight, which is not conducive to improving the energy density of the battery cell. If A is greater than 11 mm, the adhesive strip 20 is too far from the recess 103, and the width of the adhesive strip 20 is insufficient, resulting in insufficient encapsulation strength and easy problems such as delamination, affecting the sealing and safety of the battery cell. Therefore, by limiting A to a value between 8 mm and 11 mm, it is possible to avoid the waste of adhesive strip 20 material, avoid increasing weight, and improve the energy density of the battery cell, while also ensuring encapsulation strength and improving the sealing and safety of the battery cell.

[0043] Optionally, the value of A is any one of 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 10.5 mm, 11 mm, or a value between any two of these values.

[0044] In one embodiment, the value of B is in the range of 3 mm ≤ B ≤ 6 mm. If B is less than 3 mm, the adhesive strip 20 is too close to the recess 103, affecting the positioning and encapsulation of the packaging equipment. This may cause interference between the end cap and the recess 103 during the packaging process, thereby damaging the electrode assembly inside the recess 103, resulting in cell damage and a reduced pass rate. If B is greater than 6 mm, the adhesive strip 20 is too far from the recess 103, and the width of the adhesive strip 20 is insufficient, resulting in insufficient packaging strength and easy problems such as delamination, affecting the sealing and safety of the cell. Therefore, by limiting B to a value between 3 mm and 6 mm, a reasonable distance is maintained between the adhesive strip 20 and the side of the recess 103. This avoids interference between the packaging and the recess 103, facilitates the smooth progress of the packaging process, ensures the pass rate of the cell, and also ensures packaging strength, improving the sealing and safety of the cell.

[0045] Optionally, the value of B is any one of 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, or a value between any two of these values.

[0046] In one embodiment, the first encapsulation film 101 has preset positions for setting adhesive strips 20, specifically including a first preset position 11, a second preset position 12, a third preset position 13, and a fourth preset position 14 respectively corresponding to the first adhesive strip, the second adhesive strip, the third adhesive strip, and the fourth adhesive strip.

[0047] In one embodiment, further combination Figures 1 to 4As shown, the battery cell has a tab 30 on one side. The first adhesive strip is disposed on the side with the tab 30. The first preset position 11 is located on the side of the first encapsulation film 101 corresponding to the tab 30. The first adhesive strip extends along the Y direction, and the distance between the first adhesive strip and the recess 103 along the X direction is A, that is, the distance between the first preset position 11 and the recess 103 along the X direction is A. The second adhesive strip extends along the Y direction, and the distance between the second adhesive strip and the recess 103 along the X direction is B. The third and fourth adhesive strips both extend along the X direction, and the distances between the third and fourth adhesive strips and the recess 103 along the Y direction are B, respectively.

[0048] In one embodiment, further combination Figures 4 to 5 As shown, the distance between the adhesive strip 20 and the edge of the encapsulation film structure 10 along the X or Y direction is C, where the value of C ranges from 1 mm to 2 mm. It should be noted that the encapsulation film structure 10 is cut from an aluminum-plastic film. The adhesive strip 20 is suitable for melting into adhesive liquid when heated and extruded during heat sealing and covering the side edge of the encapsulation film structure 10 adjacent to the adhesive strip 20. That is, the adhesive liquid will overflow and cover the cut surface of the aluminum-plastic film, protecting the edge of the encapsulation film structure 10 and forming a sealing effect on the aluminum layer 1012. This can effectively reduce the possibility of the aluminum layer 1012 of the aluminum-plastic film being short-circuited to the negative electrode through a conductive material. C refers to the distance between the adhesive strip 20 and the edge of the encapsulation film structure 10 and the edge adjacent to the adhesive strip 20 along the direction perpendicular to the extension of the adhesive strip 20. If C is less than 1 mm, the distance between the adhesive strip 20 and the edge of the encapsulation film structure 10 is too small. During the heat sealing and extrusion process, too much adhesive will overflow from the adhesive strip 20 to the outside of the encapsulation film structure, affecting the appearance of the battery cell, the dimensional accuracy of the battery cell, and the assembly effect. It will also result in too little adhesive remaining between the first encapsulation film 101 and the second encapsulation film 102, making it difficult to effectively strengthen the encapsulation strength. If C is greater than 2 mm, the distance between the adhesive strip 20 and the edge of the encapsulation film structure 10 is too large. The overflow of adhesive may not be able to completely cover the side edge of the encapsulation film structure 10, resulting in the exposure of the aluminum layer 1012, increasing the risk of short circuit between the aluminum layer 1012 and the negative electrode, and affecting the safety and reliability of the battery cell.

[0049] Therefore, by limiting C to a value between 1 mm and 2 mm, it is possible to ensure that the adhesive liquid after the adhesive strip 20 is melted can effectively cover the side edge of the encapsulation film structure 10, protect the aluminum layer 1012, reduce the risk of short circuit, and avoid excessive adhesive overflow that would affect the dimensional accuracy and assembly effect of the battery cell. It also ensures that enough adhesive liquid remains between the first encapsulation film 101 and the second encapsulation film 102, thereby ensuring the encapsulation strength.

[0050] Optionally, the value of C is any one of 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, or a value between any two of these values.

[0051] In one embodiment, the width of the adhesive strip 20 along the X or Y direction is W, where W ranges from 3mm ≤ W ≤ 10 mm. It should be noted that the width of the adhesive strip 20 refers to its dimension in the direction perpendicular to its extension direction; for the first and second adhesive strips extending along the Y direction, the width of the adhesive strip 20 along the X direction is W; for the third and fourth adhesive strips extending along the X direction, the width of the adhesive strip 20 along the Y direction is W. If the width of the adhesive strip 20 is less than 3mm, the adhesive strip 20 is too narrow, and during the heat sealing process, the thickness of the adhesive layer formed after the adhesive strip 20 melts is insufficient, making it difficult to effectively enhance the sealing strength and easily leading to problems such as delamination or incomplete sealing; if the width of the adhesive strip 20 is greater than 10mm, the adhesive strip 20 is too wide, which not only increases material costs but also causes excessive adhesive overflow during heat sealing, affecting the appearance and dimensional accuracy of the battery cell. Therefore, by limiting W to a value between 3 mm and 10 mm, it is possible to ensure that the adhesive strip 20 forms a sufficiently thick adhesive layer after heat sealing to enhance the sealing strength, while avoiding material waste and heat sealing defects, thereby improving the overall performance and safety of the battery cell.

[0052] Optionally, the value of W is any one of 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or a value between any two of these values.

[0053] In one embodiment, the thickness of the adhesive strip 20 along the Z direction ranges from 100 μm to 500 μm. If Z is less than 100 μm, the thickness of the adhesive strip 20 is too small. During the heat sealing process, the adhesive layer formed after the adhesive strip 20 melts may be too thin, failing to effectively enhance the encapsulation strength and leading to a decrease in the sealing performance and safety of the battery cell. If Z is greater than 500 μm, the thickness of the adhesive strip 20 is too large, which not only increases material costs but may also cause excessive overflow of adhesive during heat sealing, affecting the appearance and dimensional accuracy of the battery cell. It may even put pressure on the electrode assembly inside the battery cell, affecting the performance of the battery cell.

[0054] Therefore, by limiting the thickness of the adhesive strip 20 along the Z direction to between 100 μm and 500 μm, it is possible to ensure that the adhesive strip 20 forms a sufficiently thick adhesive layer after heat sealing to enhance the encapsulation strength, while avoiding material waste and heat sealing defects. At the same time, it protects the electrode assembly inside the battery cell from pressure, thereby improving the overall performance and safety of the battery cell.

[0055] Optionally, the value of Z is any one of 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm or a value between any two of these values.

[0056] In one embodiment, the battery cell further includes tab adhesive, which is disposed between the first encapsulation film 101 and the second encapsulation film 102 and wraps around the tab 30. The tab adhesive is used to improve the insulation between the tab 30 and the encapsulation film structure 10 and to ensure the sealing between the tab 30 and the encapsulation film structure 10. In this embodiment, the adhesive strip 20 is an additional adhesive strip provided on the basis of the tab adhesive to improve the overall encapsulation strength and sealing of the encapsulation film structure 10 along the circumference of the encapsulation film structure 10.

[0057] According to an embodiment of the present invention, in another aspect, a battery cell packaging method is also provided. The battery cell packaging method is used to manufacture the battery cell described above. The battery cell packaging method includes the following steps: Step S101: Punch and cut the aluminum-plastic film to obtain a semi-finished encapsulation film. The semi-finished encapsulation film includes a first film and a second film, and the first film and / or the second film have pits 103 formed on them.

[0058] It should be noted that the aluminum-plastic film is the raw material for the encapsulation film structure 10, and further combined with... Figure 7 As shown, the aluminum-plastic film includes a protective layer 1011, an aluminum layer 1012, a heat-sealing layer 1013, a first adhesive layer 1014 located between the protective layer 1011 and the aluminum layer 1012, and a second adhesive layer 1015 located between the aluminum layer 1012 and the heat-sealing layer 1013. The encapsulation film structure 10 includes a first encapsulation film 101 and a second encapsulation film 102. The heat-sealing layer 1013 of the first encapsulation film 101 and the heat-sealing layer 1013 of the second encapsulation film 102 are disposed opposite to each other to facilitate heat sealing.

[0059] Optionally, the heat-sealing layer 1013 is made of PP, and its thickness is preferably 80 μm; the protective layer 1011 includes a nylon layer 1016 and a PET layer 1017, the PET (Polyethylene Terephthalate) layer is located on the side of the nylon layer 1016 facing away from the aluminum layer 1012, the thickness of the nylon layer 1016 is preferably 20 μm, the thickness of the PET layer 1017 is preferably 5 μm; the thickness of the aluminum layer 1012 is preferably 40 μm; the first adhesive layer 1014 and the second adhesive layer 1015 are both Adhesive Layers (ADH), the thickness of the first adhesive layer 1014 is preferably 3 μm, and the thickness of the second adhesive layer 1015 is preferably 4 μm.

[0060] It should be noted that the encapsulation film semi-finished product, such as Figure 1 As shown, the encapsulation film structure 10 required for the final battery cell includes an air pocket and excess edges. The first film includes a first encapsulation film 101 and its extended area for forming an air pocket and excess edges. The second film includes a second encapsulation film 102 and its extended area for forming an air pocket and excess edges.

[0061] Step S102: Preheat and press the adhesive strip 20 to a preset position on the first or second diaphragm.

[0062] It should be noted that the first and second films are interlocked, and the preset positions are located on the side of one of the two films facing the other, and around the circumference of the recess 103, so that the adhesive strip 20 is located between the first encapsulation film 101 and the second encapsulation film 102. The preset positions specifically include the first preset position 11 and the second preset position 12 respectively located on both sides of the recess 103 along the X direction, and the third preset position 13 and the fourth preset position 14 respectively located on both sides of the recess 103 along the Y direction. The first preset position 11, the second preset position 12, the third preset position 13, and the fourth preset position 14 are the preset positions of the first adhesive strip, the second adhesive strip, the third adhesive strip, and the fourth adhesive strip, respectively. After the aluminum-plastic film is punched, the adhesive strip 20 is placed in the preset position, and the hot press machine presses it onto the film to pre-seal the adhesive strip 20 to the heat-sealing position. The preset position ensures the accuracy of the pre-sealing position of the adhesive strip 20 and ensures the subsequent heat-sealing effect. Preferably, the first diaphragm has a recess 103 punched in it, and the preset position is located on the second diaphragm.

[0063] The length of the adhesive strip 20 along its forward extension direction matches the top and side dimensions of the battery cell, and the ends of two adjacent adhesive strips overlap each other, thereby ensuring that all adhesive strips 20 can wrap around the encapsulation film structure 10, thus ensuring a sealing effect.

[0064] Step S103: Place the electrode assembly in the recess 103 and fasten the first diaphragm and the second diaphragm together.

[0065] Specifically, the electrode assembly includes an electrode assembly body and electrode tabs 30. The electrode assembly body is located in the recess 103, and the electrode tabs extend out of the recess and at least partially extend beyond the encapsulation film structure 10. After the electrode assembly is normally placed in the recess 103, the encapsulation film semi-finished product is folded in half so that the first film and the second film are fastened together, wrapping the electrode assembly body and forming protection for the electrode assembly.

[0066] Step S104: The position on the encapsulation film semi-finished product corresponding to the adhesive strip 20 is the sealing area. The encapsulation film semi-finished product is first encapsulated along the sealing area to press the sealing area to the first preset thickness.

[0067] The first encapsulation process involves heat sealing. During heat sealing, the adhesive strip 20 melts into a liquid adhesive, and the heat sealing layer 1013 on the inner side of the encapsulation film semi-finished product also melts. Since the heat sealing layer 1013 and the adhesive strip 20 are made of the same material, PP, they can fuse together. Thus, the adhesive strip 20 and the heat sealing layer 1013 together form the PP layer of the sealing area. The total thickness of the PP layer can prevent over-sealing. The increased sealing thickness can effectively increase the encapsulation strength, prevent delamination, effectively isolate external air from entering the battery cell, and prevent the aluminum layer 1012 from contacting the electrolyte. This also prevents poor edge voltage and edge resistance of the battery cell, improves the reliability of the battery cell, and prevents battery cell failure.

[0068] Specifically, the first encapsulation uses a heat sealing device for heat sealing. The heat sealing device applies heat to the upper and lower sides of the encapsulation film semi-finished product along the Z direction with a certain heat sealing temperature, heat sealing pressure and heat sealing time, so as to press the first film and the second film to the first preset thickness along the circumferential edge of the encapsulation film semi-finished product, forming a stable sealing structure.

[0069] Step S105: Perform electrolyte injection, formation, and venting on the battery cell.

[0070] Specifically, the electrolyte injection process involves injecting electrolyte into the cell. As a medium for ion transport, the electrolyte plays a crucial role in the cell's performance. The formation process is the initial charging of the cell, causing a chemical reaction inside to form a stable solid electrolyte interphase (SEI) film. This process has a significant impact on the cell's cycle life and safety. After the cell is formed, some gas is generated. The gas bag set in the encapsulation film semi-finished product can collect the gas. The degassing (DEGAS) process is to expel the gas from the gas bag to avoid residual gas causing cell bulging, performance degradation, or safety risks. DEGAS is usually completed in a vacuum degassing machine to ensure that the cell's "pre-reserved opening edge" (the incompletely sealed edge intentionally left during encapsulation before formation, or a small opening made by laser cutting) is aligned with the venting channel. After DEGAS, the reserved electrolyte injection port side also needs to be heat-sealed to close the tiny channel left during degassing, further ensuring the cell's airtightness. The heat-sealing parameters are the same as the first heat-sealing parameters.

[0071] Step S106: Trim the excess edges of the encapsulation film semi-finished product to obtain the encapsulation film structure 10.

[0072] The cutting process includes removing excess edges around the air bag and encapsulation film structure 10 to obtain the encapsulation film structure 10 required for the finished battery cell. During air bag cutting... Figure 1 Cut along the cutting line 104.

[0073] Step S107: Perform a second encapsulation on the encapsulation film structure along the sealing area to press the sealing area to a second preset thickness, wherein the second preset thickness is less than the first preset thickness.

[0074] It should be noted that after the battery cell completes the DEGAS sealing, the excess edges are trimmed. At this point, an additional encapsulation step is added, where the PP layer is heat-pressed to the final target thickness. The second preset thickness is the final target thickness. The second encapsulation also uses a heat-sealing method. By precisely controlling parameters such as heat-sealing temperature, pressure, and time, the sealing area is further pressed to the second preset thickness. By adding a second encapsulation, the PP adhesive can overflow during the second heat-pressing to seal the aluminum layer 1012 on the cut surface of the aluminum-plastic film, achieving the purpose of insulating the aluminum layer 1012 from the outside environment. After the second encapsulation, the finished battery cell is obtained. The final finished battery cell is as follows: Figure 6 As shown.

[0075] In one embodiment, the first preset thickness is 1.1 to 1.5 times the second preset thickness.

[0076] It should be noted that if the ratio of the first preset thickness to the second preset thickness is less than 1.1 times, the thickness difference between the first and second encapsulation is too small, resulting in insufficient PP adhesive overflow during the second encapsulation. This makes it difficult to completely seal the aluminum layer 1012 on the cut surface of the aluminum-plastic film, leaving the aluminum layer 1012 exposed and affecting the safety and reliability of the battery cell. If the ratio of the first preset thickness to the second preset thickness is greater than 1.5 times, the thickness difference between the first and second encapsulation is too large, resulting in insufficient seal strength during the first encapsulation. This can easily lead to delamination during the battery cell formation process, causing battery cell failure. Therefore, by limiting the first preset thickness to between 1.1 and 1.5 times the second preset thickness, it is possible to ensure that the PP adhesive fully overflows and seals the aluminum layer 1012 during the second encapsulation, improving the safety and reliability of the battery cell, while also ensuring that the seal obtained during the first encapsulation has sufficient strength to prevent battery cell failure.

[0077] In one embodiment, the heat sealing temperature used in the second encapsulation process is 180℃~210℃, the heat sealing pressure is 0.3 MPa~0.6 MPa, and the heat sealing time is 3 s~5 s. It should be noted that due to electrolyte contamination at the DEGAS seal, false sealing is more likely to occur here, affecting the final sealing performance of the battery cell. This embodiment uses a heat sealing temperature of 180℃~210℃ in the second encapsulation process, which is 5℃~10℃ higher than the traditional heat sealing temperature. Simultaneously, the heat sealing pressure is also increased compared to the traditional heat sealing pressure. By increasing the heat sealing temperature and pressure, the adhesive strip 20 can be fully melted, and the melted adhesive strip 20 provides sufficient adhesive material, thereby forming a high-strength, thick sealing strip, effectively preventing false sealing. Simultaneously, during the heat sealing compression, the adhesive strip 20 overflows and covers the cut surface of the aluminum-plastic film, forming a sealing effect on the aluminum layer, effectively reducing the possibility of short circuit between the aluminum layer of the aluminum-plastic film and the negative electrode through conductive materials.

[0078] The following examples and comparative examples verify the impact of different heat sealing parameter values ​​on the packaging results during the second packaging process. The examples and comparative examples are shown in Table 1.

[0079] Table 1

[0080] It should be noted that, for the battery cell of Example 1, the aluminum-plastic film is cut and perforated according to the normal process. The adhesive strip 20 is fixed in the preset position by preheating and pressing. The electrode group is inserted into the perforation normally. The aluminum-plastic film is folded in half for the first encapsulation. At this time, the top and side seals control the seal thickness. The seal thickness is controlled to be 1.1-1.5 times the final target thickness. The PP layer thickness is also 1.1-1.5 times the final PP layer thickness. The process continues according to the normal process. After the battery cell completes the DEGAS seal, the excess edges are cut off. At this time, a second encapsulation is added. During the heat sealing process, the heat sealing temperature is 180°C, the heat sealing pressure is 0.3MPa, and the heat sealing time is 3s. The seal and PP layer are heat-pressed to the final target thickness. The battery cell of Example 2 follows the same process as in Example 1 before the second encapsulation. The difference is that the heat sealing temperature used in the second encapsulation is 180°C, the heat sealing pressure is 0.4 MPa, and the heat sealing time is 4 seconds. The battery cell of Example 3 follows the same process as in Example 1 before the second encapsulation. The difference is that the heat sealing temperature used in the second encapsulation is 180°C, the heat sealing pressure is 0.5 MPa, and the heat sealing time is 5 seconds. The battery cell of Example 4 follows the same process as in Example 1 before the second encapsulation. The difference is that the heat sealing temperature used in the second encapsulation is 190°C, the heat sealing pressure is 0.3 MPa, and the heat sealing time is 4 seconds. The battery cell of Example 5 follows the same process as in Example 1 before the second encapsulation. The difference is that the heat sealing temperature used in the second encapsulation is 190°C, the heat sealing pressure is 0.4 MPa, and the heat sealing time is 5 seconds. The battery cell of Example 6 follows the same process as in Example 1 before the second encapsulation. The difference is that the heat sealing temperature used in the second encapsulation is 190°C, the heat sealing pressure is 0.5 MPa, and the heat sealing time is 3 seconds. The battery cell of Example 7 follows the same process as in Example 1 before the second encapsulation. The difference is that the heat sealing temperature used in the second encapsulation is 200°C, the heat sealing pressure is 0.3 MPa, and the heat sealing time is 5 seconds. The battery cell of Example 8 follows the same process as in Example 1 before the second encapsulation. The difference is that the heat sealing temperature used in the second encapsulation is 200°C, the heat sealing pressure is 0.4 MPa, and the heat sealing time is 3 seconds. The battery cell of Example 9 follows the same process as in Example 1 before the second encapsulation. The difference is that the heat sealing temperature used in the second encapsulation is 200°C, the heat sealing pressure is 0.5 MPa, and the heat sealing time is 4 seconds.

[0081] For the battery cell of Comparative Example 1, the process before the second packaging is the same as in Example 1. The difference is that the heat sealing temperature used in the second packaging is 170°C, the heat sealing pressure is 0.3 MPa, and the heat sealing time is 5s.

[0082] For the battery cell of Comparative Example 2, the process before the second packaging is the same as in Example 1. The difference is that the heat sealing temperature used in the second packaging is 220°C, the heat sealing pressure is 0.3 MPa, and the heat sealing time is 5s.

[0083] For the battery cell of Comparative Example 3, the process before the second packaging is the same as in Example 1. The difference is that the heat sealing temperature used in the second packaging is 200°C, the heat sealing pressure is 0.2 MPa, and the heat sealing time is 5s.

[0084] For the battery cell of Comparative Example 4, the process before the second packaging is the same as in Example 1. The difference is that the heat sealing temperature used in the second packaging is 200°C, the heat sealing pressure is 0.7 MPa, and the heat sealing time is 5s.

[0085] For the battery cell of Comparative Example 5, the process before the second packaging is the same as in Example 1. The difference is that the heat sealing temperature used in the second packaging is 200°C, the heat sealing pressure is 0.3 MPa, and the heat sealing time is 2s.

[0086] For the battery cell of Comparative Example 6, the process before the second packaging is the same as in Example 1. The difference is that the heat sealing temperature used in the second packaging is 190°C, the heat sealing pressure is 0.5 MPa, and the heat sealing time is 6 seconds.

[0087] For the battery cells of Examples 1 to 9, the heat sealing parameters are all within the range defined in this application. After the battery cell is packaged, the sealing strength test is performed on the battery cell. The results show that the tensile force that the seal can withstand for the battery cells of Examples 1 to 9 is 258 N / 25cm, 269 N / 25cm, 298 N / 25cm, 283 N / 25cm, 295 N / 25cm, 303 N / 25cm, 308 N / 25cm, 296 N / 25cm, and 285 N / 25cm, respectively. The tensile force that the seal can withstand is relatively large, and the sealing strength test is qualified.

[0088] For the battery cell of Comparative Example 1, the heat sealing temperature used during the second encapsulation was 170°C, which is lower than the lower limit of 180°C defined in this application and is not within the range defined in this application. After the battery cell was encapsulated, the battery cell was subjected to a seal strength test. The tensile force that the battery cell seal could withstand was 217 N / 25 cm, which is significantly lower than that of the embodiment.

[0089] In Comparative Example 2, the heat sealing temperature used during the second encapsulation of the battery cell was 220°C, which is higher than the upper limit of 210°C defined in this application and is not within the range defined in this application. After the battery cell was encapsulated, the sealing strength test was performed on the battery cell. The tensile force that the battery cell's seal could withstand was 198 N / 25cm, which is significantly lower than that of the embodiment.

[0090] In Comparative Example 3, the heat sealing pressure used during the second encapsulation of the battery cell was 0.2 MPa, which is less than the lower limit of 0.3 MPa defined in this application and is not within the range defined in this application. After the battery cell was encapsulated, the sealing strength test was performed on the battery cell. The tensile force that the battery cell's seal could withstand was 189 N / 25 cm, which is significantly lower than that of the embodiment.

[0091] In Comparative Example 4, the heat sealing pressure used during the second encapsulation of the battery cell was 0.7 MPa, which is greater than the upper limit of 0.6 MPa defined in this application and is not within the range defined in this application. After the battery cell was encapsulated, the battery cell was subjected to a seal strength test. The tensile force that the battery cell seal could withstand was 206 N / 25 cm, which is significantly lower than that of the embodiment.

[0092] In Comparative Example 5, the heat sealing time during the second encapsulation was 2 seconds, which is less than the lower limit of 2 seconds defined in this application and is not within the range defined in this application. After the cell encapsulation was completed, the cell was subjected to a seal strength test. The tensile force that the cell seal could withstand was 199 N / 25 cm, which is significantly lower than that of the embodiment.

[0093] In Comparative Example 6, the heat sealing time during the second encapsulation was 6 seconds, which is greater than the upper limit of 5 seconds defined in this application and is not within the range defined in this application. After the cell encapsulation was completed, the cell was subjected to a seal strength test. The tensile force that the cell seal could withstand was 220 N / 25 cm, which is significantly lower than that of the embodiment.

[0094] In summary, when any one of the heat sealing temperature, heat sealing pressure, or heat sealing time used in the second encapsulation exceeds the range defined in this application, the heat sealing strength is significantly reduced compared to the embodiments, and it is not suitable for use.

[0095] It is evident that the range of heat sealing temperature, heat sealing pressure, and heat sealing time used for the second sealing as defined in this application is the optimal range. By setting the heat sealing parameters within the range defined in this application, sufficient strength of the seal can be guaranteed.

[0096] In addition, the seal in Example 7 can withstand the greatest tensile force and has the highest seal strength. It can be seen that selecting heat sealing process parameters of 200°C, 0.3 MPa, and 5s can achieve the best heat sealing effect.

[0097] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using testing methods commonly used in the art, such as testing the tensile strength that the seal can withstand using an electronic universal testing machine or a peel testing machine. Unless otherwise stated, the test temperature for all parameters is 25°C.

[0098] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An electric cell, characterized by, include: The pole assembly includes the pole assembly body and the pole tabs; The encapsulation film structure includes a first encapsulation film and a second encapsulation film that are interlocked with each other. At least one of the first encapsulation film and the second encapsulation film is provided with a pit, which is adapted to accommodate the electrode assembly body. An adhesive strip is disposed between the first encapsulation film and the second encapsulation film, and is spaced apart from the recess. The encapsulation film structure is adapted to be heat-sealed at a position corresponding to the adhesive strip.

2. The electric cell of claim 1, wherein, The adhesive strip is arranged circumferentially around the recess.

3. The electric cell of claim 2, wherein, The adhesive strip includes a first adhesive strip and a second adhesive strip disposed on both sides of the recess along the X direction, and a third adhesive strip and a fourth adhesive strip disposed on both sides of the recess along the Y direction.

4. The electric cell of claim 3, wherein, At least a portion of the tab is located between the first encapsulation film and the second encapsulation film, and at least a portion extends out of the encapsulation film structure; The adhesive strip extends along the X or Y direction. In the direction perpendicular to the extension of the adhesive strip, the distance between the adhesive strip corresponding to the tab and the edge of the recess is A, and the distance between the adhesive strip not corresponding to the tab and the edge of the recess is B, wherein A is greater than B.

5. The electric cell of claim 4, wherein, The range of values ​​for A is: 8 mm ≤ A ≤ 11 mm; and / or, the range of values ​​for B is: 3 mm ≤ B ≤ 6 mm.

6. The electric cell of claim 1, wherein, The distance between the adhesive strip and the edge of the encapsulation film structure along the X or Y direction is C, where the value of C ranges from 1 mm to 2 mm.

7. The electric cell of any one of claims 1 to 6, wherein, The width of the adhesive strip along the X or Y direction is W, wherein the value of W is in the range of 3 mm ≤ W ≤ 10 mm; And / or, the thickness of the adhesive strip along the Z direction ranges from 100 μm to 500 μm.

8. A method of packaging a battery cell, the method comprising: The cell packaging method is used to manufacture the cell according to any one of claims 1 to 7, the cell packaging method comprising: The aluminum-plastic film is punched and cut to obtain a semi-finished encapsulation film, which includes a first film and a second film, and the first film and / or the second film have pits formed on them. The adhesive strip is preheated and pressed to a preset position on the first or second diaphragm; The electrode assembly is placed in the recess, and the first diaphragm and the second diaphragm are fastened together. The position on the encapsulation film semi-finished product corresponding to the adhesive strip is the sealing area. The encapsulation film semi-finished product is first encapsulated along the sealing area to press the sealing area to a first preset thickness. The battery cell is subjected to electrolyte injection, formation, and venting. The excess edges of the encapsulation film semi-finished product are trimmed to obtain the encapsulation film structure; The encapsulation film structure is encapsulated a second time along the sealing area to press the sealing area to a second preset thickness, wherein the second preset thickness is less than the first preset thickness.

9. The method of claim 8, wherein, The first preset thickness is 1.1 to 1.5 times the second preset thickness.

10. The method of claim 8, wherein, The heat sealing temperature used in the second encapsulation process is 180 ℃~210 ℃, the heat sealing pressure is 0.3 MP~0.6 MP, and the heat sealing time is 3 s~5 s.

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