Battery monomer

Abstract

The utility model relates to the technical field of batteries, and discloses a battery monomer, which comprises a shell, a roll core accommodated in the shell and an insulating film, the insulating film comprises a main body film and an end surface film, the end surface film is connected with the main body film, the roll core has a first direction, one end of the roll core in the first direction is connected with a tab, and the tab is connected with the shell. The end face film wraps the end, away from the tab, of the roll core in the first direction, the roll core is provided with a peripheral side face arranged around the first direction, the two ends of the main body film wrap the peripheral side face around the first direction to form an overlapping connecting part, and the overlapping connecting part is located on one face of the peripheral side face of the roll core. According to the battery monomer disclosed by the utility model, the number of interfaces of the insulating film on the peripheral side of the roll core is reduced, namely the overlapping part of the insulating film on the peripheral side of the roll core is reduced, the poor coating condition is reduced, the total use amount of the insulating film is reduced, and the production cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a battery monomer. Background Art

[0002] At present, power batteries use insulating film to wrap the core to achieve insulation inside the cell. The existing one-piece insulating film is wrapped in a U-shaped wrapping method. After wrapping, the two opposite sides of the cell have overlapping parts and are sealed after hot melting. Since two seals need to be hot-melted, the number of seals is large, and poor wrapping is prone to occur during hot melting. The outer circumference of the core after wrapping the insulating film exceeds the expected design size. When the core is assembled with the aluminum shell, the side of the core will interfere with the aluminum shell, causing scratches and affecting subsequent tooling, thereby affecting the performance, safety and production of the cell. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. The utility model provides a battery cell, which reduces the number of interfaces of the insulating film on the side of the winding core, that is, reduces the overlapping part of the insulating film on the side of the winding core, reduces the poor coating situation, reduces the overall amount of the insulating film, and reduces the production cost.

[0004] In order to achieve the above-mentioned purpose, the utility model provides a battery cell, including a shell, a winding core accommodated in the shell and an insulating film, the insulating film including a main body film and an end face film, the end face film is connected to the main body film, the winding core has a first direction, the winding core is connected to a pole ear at one end in the first direction, the end face film is coated on the end of the winding core away from the pole ear in the first direction, the winding core has a peripheral side surface arranged around the first direction, the two ends of the main body film are coated on the peripheral side surface around the first direction to form an overlapping connection portion, and the overlapping connection portion is located on one side of the peripheral side surface of the winding core.

[0005] As a preferred embodiment, the winding core has a second direction, the first direction intersects with the second direction, and the main body film includes a main body surrounding portion wrapped around the peripheral side surface, a first connecting portion and a second connecting portion, the first connecting portion and the second connecting portion are both connected to the opposite sides of the main body surrounding portion in the second direction, and the first connecting portion and the second connecting portion at least partially overlap and are connected to form the overlapping connecting portion.

[0006] As a preferred solution, the width W of the overlapping connection portion in the second direction is set at 8-10 mm.

[0007] As a preferred solution, the main body surrounding portion includes a first side surface and two second side surfaces oppositely arranged along the second direction. The area of the second side surface is larger than that of the first side surface. The two second side surfaces are oppositely connected to the first side surface in the second direction. The first connecting portion is connected to one side of the second side surface away from the first side surface in the second direction, and the second connecting portion is connected to the other side of the second side surface away from the first side surface in the second direction.

[0008] As a preferred solution, the end face film includes a first end face film and a second end face film. The winding core has a second direction, and the first direction intersects with the second direction. The first end face film and the second end face film are respectively oppositely connected to the main body film in the second direction, and the opposite faces of the first end face film and the second end face film are spliced to form the end face film.

[0009] As a preferred solution, the winding core has a third direction, and the third direction intersects with the first direction and the second direction respectively. Both the first end face film and the second end face film extend along the third direction, and the opposite faces of the first end face film and the second end face film in the second direction are spliced.

[0010] As a preferred solution, the winding core has a third direction, and the third direction intersects with the first direction and the second direction respectively. At least two first end face films are provided. The adjacent first end face films are arranged at intervals along the third direction to form a splicing port, and the second end face film is located at the splicing port and is spliced with the first end face film.

[0011] As a preferred solution, the battery cell further includes a support plate, and the support plate is connected between the end face film and the housing.

[0012] As a preferred solution, the winding core has a second direction and a third direction, and the third direction intersects with the first direction and the second direction respectively. The battery cell further includes an adhesive tape. There is a connection port between one end of the main body film in the third direction and the end face film. A part of the adhesive tape is connected to the main body film, and a part of the adhesive tape is connected to the support plate. The connection port is covered by the adhesive tape.

[0013] As a preferred solution, the battery further includes a top cover assembly. The top cover assembly includes a top cover sheet and a lower plastic. One end of the housing in the first direction is provided with a cover plate installation port. The insulating film is installed in the housing through the cover plate installation port. The lower plastic is connected to the side of the top cover sheet facing the housing. The lower plastic is inserted into the housing through the cover plate installation port and is heat-melted and connected to the overlapping connection portion. The top cover sheet is installed in the cover plate installation port and is connected to the housing.

[0014] Compared with the prior art, an embodiment of the present utility model has the following beneficial effects: The housing is used to place the winding core and the insulating film. The insulating film and the winding core are accommodated in the housing, and the winding core is insulated from the housing through the insulating film. Among them, the insulating film includes a main body film and an end face film. The end face film is connected to the main body film and covers one end of the winding core in the first direction. The end face film is located between the housing and the winding core to achieve insulation between one end of the winding core in the first direction and the housing. The main body film wraps around the circumferential side of the winding core in the first direction to achieve insulation between the winding core and the housing on the circumferential side. The main body film forms an overlapping connection part on the circumferential side of the winding core. After the insulating film covers the winding core, the overall thickness on the circumferential side is small, avoiding interference on the circumferential side during the assembly of the winding core and the housing, avoiding abrasion between the insulating film and the housing, reducing the impact on subsequent tooling, ensuring the performance and use safety of the battery cell, and improving the production yield. At the same time, the number of overlapping connection parts is small, reducing the risk of poor covering caused by hot melting of the overlapping connection parts. Description of the Drawings

[0015] Figure 1 is a schematic structural diagram of the insulating film covering the winding core in an embodiment of the present utility model.

[0016] Figure 2 is a schematic structural diagram of the insulating film when unfolded in an embodiment of the present utility model.

[0017] Figure 3 is a schematic structural diagram of the top cover assembly assembled to the housing in an embodiment of the present utility model.

[0018] Figure 4 is a schematic structural diagram of the adhesive tape and the tray respectively assembled with the insulating film in an embodiment of the present utility model.

[0019] Figure 5 is a schematic structural diagram of the adhesive tape and the tray respectively disassembled from the insulating film in an embodiment of the present utility model.

[0020] Figure 6 is a schematic structural diagram of the tray in an embodiment of the present utility model.

[0021] Figure 7 is a schematic structural diagram of the insulating film assembled with the top cover assembly in an embodiment of the present utility model.

[0022] Figure 8 is a schematic structural diagram of the insulating film disassembled from the top cover assembly in an embodiment of the present utility model.

[0023] Figure 9 is a schematic structural diagram of the insulating film during cutting in an embodiment of the present utility model.

[0024] In the figure:

[0025] 10. Housing; 11. Cover plate mounting opening;

[0026] 20. Core; 21. Tab

[0027] 30. Insulating film; 31. Main body film; 311. Main body surrounding part; 3111. First side; 3112. Second side; 312. First connecting part; 313. Second connecting part; 314. Overlapping connecting part; 32. End face film; 321. First end face film; 3211. Joint; 322. Second end face film; 323. First infiltration hole; 33. Connecting port

[0028] 40. Support plate; 41. Second infiltration hole

[0029] 50. Adhesive sticker

[0030] 60. Top cover assembly; 61. Top cover sheet; 62. Lower plastic; 621. Heat-melt surface

[0031] X. First direction; Y. Second direction; Z. Third direction Detailed implementation manners

[0032] The following combines the drawings and embodiments to further describe in detail the specific implementation manners of the present utility model. The following embodiments are used to illustrate the present utility model, but are not used to limit the scope of the present utility model

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

[0034] In this application, the term "parallel" not only includes the case of absolute parallelism, but also includes the case of approximately parallelism commonly recognized in engineering. For example, "parallel" means that the angle formed by a straight line and a straight line, a straight line and a plane, or a plane and a plane is in the state of -1° to 1°; at the same time, "perpendicular" not only includes the case of absolute perpendicularity, but also includes the case of approximately perpendicularity commonly recognized in engineering. For example, "perpendicular" means that the angle formed by a straight line and a straight line, a straight line and a plane, or a plane and a plane is in the state of 89° to 91°. Equal distance or equal angle not only includes the case of absolute equality, but also includes the case of approximately equality commonly recognized in engineering, that is, there can be a certain error, such as the state within the tolerance range of -1% to 1%

[0035] In the description of the present invention, it should be understood that the terms "connected", "connected", "fixed" and the like used in the present invention should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, or a welding connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] like Figure 1 , Figure 4 as well as Figures 7 to 8 As shown, a battery cell of a preferred embodiment of the utility model embodiment comprises a shell 10, a winding core 20 accommodated in the shell 10 and an insulating film 30, the insulating film 30 comprises a main body film 31 and an end face film 32, the end face film 32 is connected to the main body film 31, the winding core 20 has a first direction X, the winding core 20 is connected to the pole ear 21 at one end in the first direction X, the end face film 32 is coated on the end of the winding core 20 away from the pole ear 21 in the first direction X, the winding core 20 has a peripheral side surface arranged around the first direction X, the two ends of the main body film 31 are coated on the peripheral side surface around the first direction X, and an overlapping connection portion 314 is formed, and the overlapping connection portion 314 is located on one side of the peripheral side surface of the winding core 20.

[0037] In the battery cell of the present invention, the shell 10 is used to place the winding core 20 and the insulating film 30. The insulating film 30 and the winding core 20 are contained in the shell 10, and the winding core 20 is insulated from the shell 10 by the insulating film 30. The insulating film 30 includes a main body film 31 and an end face film 32. The end face film 32 is connected to the main body film 31 and covers one end of the winding core 20 in the first direction X. The end face film 32 is located between the shell 10 and the winding core 20, so as to achieve the insulation between one end of the winding core 20 in the first direction X and the shell 10. The main body film 31 is wrapped around the side surface of the core 20 in the first direction X to achieve the insulation setting of the core 20 and the shell 10 on the side surface. The main body film 31 forms an overlapping connection part 314 on the side surface of the core 20. After the insulating film 30 is wrapped around the core 20, the overall thickness of the side surface is small, which avoids interference on the side surface when the core 20 and the shell 10 are assembled, and avoids scratches between the insulating film 30 and the shell 10, reducing the impact on subsequent tooling, ensuring the performance and safety of the battery cell, and improving the production yield. At the same time, the number of overlapping connection parts 314 is small, reducing the risk of poor coating caused by hot melting of the overlapping connection parts 314.

[0038] Further, such as Figures 1 to 2As shown, the core 20 has a second direction Y, and a first direction X intersects with the second direction Y. The main body film 31 includes a main body surrounding portion 311 covering the circumferential side surface, a first connecting portion 312, and a second connecting portion 313. Both the first connecting portion 312 and the second connecting portion 313 are connected to opposite sides of the main body surrounding portion 311 in the second direction Y. The first connecting portion 312 and the second connecting portion 313 at least partially overlap and are connected to form an overlapping connecting portion 314. The first connecting portion 312 and the second connecting portion 313 are respectively connected to opposite sides of the main body surrounding portion 311 in the second direction Y, and at least a part of the ends of the first connecting portion 312 and the second connecting portion 313 away from the main body surrounding portion 311 overlap in the second direction Y, so as to be thermally fused to form the overlapping connecting portion 314, improving the yield rate of the overlapping connecting portion 314.

[0039] Further, as Figure 1 shown, the width W of the overlapping connecting portion 314 in the second direction Y is set to be 8 - 10 mm. The width W of the overlapping connecting portion 314 is set within a suitable range, which can avoid material waste and save production costs on the basis of ensuring the thermal fusion yield rate of the overlapping connecting portion 314.

[0040] Further, as Figure 2 and Figure 9 shown, the main body surrounding portion 311 includes a first side surface 3111 and two second side surfaces 3112 oppositely arranged along the second direction Y. The area of the second side surfaces 3112 is larger than that of the first side surface 3111. The two second side surfaces 3112 are oppositely connected to the first side surface 3111 in the second direction Y. The first connecting portion 312 is connected to one side of one of the second side surfaces 3112 away from the first side surface 3111 in the second direction Y, and the second connecting portion 313 is connected to one side of the other second side surface 3112 away from the first side surface 3111 in the second direction Y. The main body surrounding portion 311 is integrally formed by connecting the first side surface 3111 with the two second side surfaces 3112 respectively. The main body surrounding portion 311 covers most of the area of the circumferential side surface of the core 20, reducing the number of overlapping connecting portions 314 and reducing the risk of poor coating caused by thermal fusion of the overlapping connecting portions 314.

[0041] Further, as Figure 2 and Figure 5 and Figure 9As shown in the figure, the end face film 32 includes a first end face film 321 and a second end face film 322. The core 20 has a second direction Y, the first direction X intersects with the second direction Y, the first end face film 321 and the second end face film 322 are respectively connected to the main body film 31 relatively in the second direction Y, and the opposite faces of the first end face film 321 and the second end face film 322 are spliced to form the end face film 32. One end of the first end face film 321 in the second direction Y is connected to one end of the main body film 31 in the first direction X, one end of the second end face film 322 in the second direction Y is connected to one end of the main body film 31 in the first direction X, and the first end face film 321 and the second end face film 322 respectively form opposite faces on the side away from the main body film 31 for splicing, so as to cover one end face of the core 20 in the first direction X, so as to realize the insulation setting of the end face of the core 20 and the housing 10.

[0042] Further, as Figure 2 and Figure 5 shown in the figure, the core 20 has a third direction Z, the third direction Z intersects with the first direction X and the second direction Y respectively, the first end face film 321 and the second end face film 322 both extend along the third direction Z, and the opposite faces of the first end face film 321 and the second end face film 322 in the second direction Y are spliced. The first end face film 321 and the second end face film 322 extend along the third direction Z and are spliced on the opposite faces in the second direction Y. The splicing structure is simple, convenient for processing, and improves production efficiency.

[0043] Further, as Figure 9 shown in the figure, the core 20 has a third direction Z, the third direction Z intersects with the first direction X and the second direction Y respectively, at least two first end face films 321 are provided, and the adjacent first end face films 321 are arranged at intervals along the third direction Z to form a splicing port 3211, and the second end face film 322 is located at the splicing port 3211 and is spliced with the first end face film 321. The second end face film 322 and the first end face film 321 are spliced to form opposite faces in the third direction Z. The splicing structure is simple, convenient for processing, and improves production efficiency. At the same time, as Figure 9 shown in the figure, when the insulating film is cut as a whole, two insulating films are cut synchronously, the operation is simple, and material waste is reduced.

[0044] Further, as Figures 4 to 6 shown in the figure, the battery cell further includes a support plate 40, and the support plate 40 is connected between the end face film 32 and the housing 10. The bottom support strength of the battery is strengthened through the support plate 40.

[0045] Further, as Figures 4 to 6As shown in the figure, the end face film 32 is provided with a first infiltration hole 323, and the support plate 40 is provided with a second infiltration hole 41. The first infiltration hole 323 and the second infiltration hole 41 are arranged in a staggered manner. After the packaged core 20 is installed in the housing 10, electrolyte is injected into the core 20. The electrolyte contacts the core 20 through the first infiltration hole 323, improving the infiltration effect of the electrolyte on the core 20 and enhancing the working efficiency of the battery. During the process of assembling the core 20 into the housing 10, conductive foreign matters (such as aluminum chips, copper chips, powder chips, etc.) may enter the housing 10. The first infiltration hole 323 and the second infiltration hole 41 are arranged in a staggered manner, isolating the conductive contact between the core 20 and the housing 10 through the conductive foreign matters, and preventing the core 20 from conducting electricity with the housing 10, thereby avoiding the corrosion of the housing 10.

[0046] Further, as Figures 4 to 5 shown, the core 20 has a second direction Y and a third direction Z. The third direction Z intersects with the first direction X and the second direction Y respectively. The battery cell further includes an adhesive patch 50. There is a connection port 33 between one end of the main body film 31 in the third direction Z and the end face film 32. A part of the adhesive patch 50 is connected to the main body film 31, and a part of the adhesive patch 50 is connected to the support plate 40. The connection port 33 is covered by the adhesive patch 50. The end face film 32 and the main body film 31 are fixed by the adhesive patch 50, preventing the end face film 32 and the main body film 31 from shifting during the assembly process, resulting in the failure of the insulation between the core 20 and the housing 10, ensuring the performance and use safety of the battery core, and improving the production yield.

[0047] Further, as Figure 3 and Figures 7 to 8 shown, the battery further includes a top cover assembly 60. The top cover assembly 60 includes a top cover piece 61 and a lower plastic 62. One end of the housing 10 in the first direction X is provided with a cover plate installation port 11. The insulating film 30 is installed in the housing 10 through the cover plate installation port 11. The lower plastic 62 is connected to the side of the top cover piece 61 facing the housing 10. The lower plastic 62 is inserted into the housing 10 through the cover plate installation port 11 and is heat-melted and connected to the overlapping connection part 314. The top cover piece 61 is installed in the cover plate installation port 11 and is connected to the housing 10. The core 20 is installed in the housing 10, and the top cover assembly 60 closes the cover plate installation port 11 of the housing 10 to form a whole battery, preventing foreign matters from entering the core 20 and playing a protective role for the core 20. Specifically, the top cover piece 61 is connected to the housing 10 to close the cover plate installation port 11. One end of the lower plastic 62 in the first direction X is connected to the top cover piece 61, and the other end of the lower plastic 62 in the first direction X is inserted into the housing 10 through the cover plate installation port 11 and is heat-melted with the overlapping connection part 314, fixing one end of the insulating film 30 in the first direction X and preventing the insulating film 30 from shifting during use, thereby enhancing the use safety.

[0048] In summary, the embodiment of the present utility model provides a battery. The housing 10 is used to place the winding core 20 and the insulating film 30. The insulating film 30 and the winding core 20 are accommodated in the housing 10, and the winding core 20 is insulated from the housing 10 through the insulating film 30. Among them, the insulating film 30 includes a main body film 31 and an end face film 32. The end face film 32 is connected to the main body film 31 and covers one end of the winding core 20 in the first direction X. The end face film 32 is located between the housing 10 and the winding core 20 to insulate one end of the winding core 20 in the first direction X from the housing 10. The main body film 31 wraps around the circumferential side surface of the winding core 20 in the first direction X to insulate the winding core 20 from the housing 10 on the circumferential side surface. The main body film 31 forms an overlapping connection part 314 on the circumferential side surface of the winding core 20. After the insulating film 30 wraps around the winding core 20, the overall thickness on the circumferential side surface is small, which avoids interference on the circumferential side surface when the winding core 20 and the housing 10 are assembled, avoids rubbing between the insulating film 30 and the housing 10, reduces the influence on subsequent tooling, ensures the performance and use safety of the battery cell, and improves the production yield. At the same time, the number of overlapping connection parts 314 is small, reducing the risk of poor coating caused by hot melting of the overlapping connection parts 314.

[0049] The above is only the preferred embodiment of the present utility model. It should be noted that for those of ordinary skill in the art of this technology, without departing from the technical principle of the present utility model, several improvements and replacements can be made, and these improvements and replacements should also be regarded as the protection scope of the present utility model.

Claims

1. A battery cell, characterized in that: The invention comprises a shell (10), a winding core (20) accommodated in the shell (10), and an insulating film (30), wherein the insulating film (30) comprises a main body film (31) and an end face film (32), wherein the end face film (32) is connected to the main body film (31), the winding core (20) has a first direction (X), and the winding core (20) is connected to a pole ear (21) at one end in the first direction (X), and the end face film (32) is coated on an end of the winding core (20) away from the pole ear (21) in the first direction (X), and the winding core (20) has a peripheral side surface arranged around the first direction (X), and the two ends of the main body film (31) are coated on the peripheral side surface around the first direction (X), forming an overlapping connection portion (314), and the overlapping connection portion (314) is located on one side of the peripheral side surface of the winding core (20).

2. The battery cell according to claim 1, characterized in that: The winding core (20) has a second direction (Y), the first direction (X) intersects with the second direction (Y), the main body film (31) includes a main body surrounding portion (311) wrapped around the peripheral side surface, a first connecting portion (312) and a second connecting portion (313), the first connecting portion (312) and the second connecting portion (313) are both connected to the main body surrounding portion (311) on opposite sides of the second direction (Y), the first connecting portion (312) and the second connecting portion (313) at least partially overlap and are connected to form the overlapping connecting portion (314).

3. The battery cell according to claim 2, characterized in that: The width W of the overlapping connection portion (314) in the second direction (Y) is set at 8-10 mm.

4. The battery cell according to claim 3, characterized in that: The main body surrounding portion (311) includes a first side surface (3111) and two second side surfaces (3112) arranged opposite to each other along the second direction (Y), the area of ​​the second side surface (3112) is larger than that of the first side surface (3111), the two second side surfaces (3112) are relatively connected to the first side surface (3111) in the second direction (Y), the first connecting portion (312) is connected to a side of one of the second side surfaces (3112) away from the first side surface (3111) in the second direction (Y), and the second connecting portion (313) is connected to a side of the other second side surface (3112) away from the first side surface (3111) in the second direction (Y).

5. The battery cell according to claim 1, characterized in that: The end face membrane (32) comprises a first end face membrane (321) and a second end face membrane (322); the winding core (20) has a second direction (Y); the first direction (X) intersects with the second direction (Y); the first end face membrane (321) and the second end face membrane (322) are respectively connected to the main body membrane (31) in the second direction (Y); the opposite surfaces of the first end face membrane (321) and the second end face membrane (322) are spliced ​​to form the end face membrane (32).

6. The battery cell according to claim 5, characterized in that: The winding core (20) has a third direction (Z), and the third direction (Z) intersects with the first direction (X) and the second direction (Y) respectively. The first end face film (321) and the second end face film (322) both extend along the third direction (Z), and the first end face film (321) and the second end face film (322) are spliced ​​at opposite surfaces in the second direction (Y).

7. The battery cell according to claim 5, characterized in that: The winding core (20) has a third direction (Z), and the third direction (Z) intersects with the first direction (X) and the second direction (Y) respectively. At least two first end face films (321) are provided, and adjacent first end face films (321) are arranged at intervals along the third direction (Z) to form a splicing interface (3211). The second end face film (322) is located at the splicing interface (3211) and is spliced ​​with the first end face film (321).

8. The battery cell according to claim 1, characterized in that: The battery cell further comprises a support plate (40), wherein the support plate (40) is connected between the end surface membrane (32) and the shell (10).

9. The battery cell according to claim 8, characterized in that: The end face membrane (32) is provided with a first wetting hole (323), the support plate (40) is provided with a second wetting hole (41), and the first wetting hole (323) and the second wetting hole (41) are arranged in a staggered manner.

10. The battery cell according to claim 8, characterized in that: The winding core (20) has a second direction (Y) and a third direction (Z), and the third direction (Z) intersects with the first direction (X) and the second direction (Y) respectively. The battery cell also includes a sticker (50), and the main body film (31) has a connection port (33) between one end in the third direction (Z) and the end face film (32). A portion of the sticker (50) is connected to the main body film (31), and a portion of the sticker (50) is connected to the support plate (40), and the connection port (33) is covered by the sticker (50).

11. The battery cell according to claim 1, characterized in that: The battery cell further comprises a top cover assembly (60), the top cover assembly (60) comprising a top cover sheet (61) and a lower plastic (62); the shell (10) is provided with a cover plate mounting opening (11) at one end in the first direction (X); the insulating film (30) is mounted in the shell (10) through the cover plate mounting opening (11); the lower plastic (62) is connected to a side of the top cover sheet (61) facing the shell (10); the lower plastic (62) is inserted into the shell (10) through the cover plate mounting opening (11) and is thermally melt-connected to the overlapping connection portion (314); the top cover sheet (61) is mounted on the cover plate mounting opening (11) and is connected to the shell (10).

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