Film sleeving device for battery cell assembly

Abstract

The invention relates to the technical field of batteries, and provides a film sleeving device for battery cell assembly, and the film sleeving device comprises a shaping mechanism which is used for shaping a tubular insulating film, so that the opening shape of the insulating film is matched with the cross section shape of the peripheral side wall of a pole group, and the shaped insulating film can move along the axial direction of the insulating film under the action of external traction; the guiding tool comprises an assembling part and a guiding part, the assembling part is provided with a first end and a second end which are opposite, the first end is suitable for being assembled with one end of the pole group, the second end is connected with the guiding part, and the guiding part is gradually shrunk in the direction away from the first end; a slot is formed in the first end of the assembling part, one end of the pole group can be inserted into the slot, and an avoiding slot is formed in the slot and is suitable for accommodating a pole lug of the pole group; when the insulating film moves in the axial direction, the insulating film can be arranged on the outer side of the pole group in a sleeving mode under the guiding effect of the guiding part. According to the invention, rapid film sleeving of the pole group can be realized, and the film sleeving efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a film sleeve device for assembling battery cells. Background Art

[0002] As lithium-ion battery technology matures, it is widely used as a power battery in electric vehicles and energy storage, leading to increasing demands for performance and safety. The assembly process for blade lithium batteries involves first coating the electrode assembly with an insulating film, inserting the electrode assembly into the housing, and finally sealing the cover plate with the housing to enclose the electrode assembly within the housing to form a battery cell. The battery cell is charged and discharged through the positive and negative electrode covers at both ends, with the insulating film preventing short circuits between the electrode assembly and the housing.

[0003] In the prior art, when the insulating film wraps the electrode group and then enters the shell, the insulating film at the end of the electrode group entering the shell is prone to large wrinkles, which may cause the insulating film to be scratched. During the shell entry process, the bulging area of ​​the insulating film is also easily scratched by the shell opening, and the insulating film is prone to slippage, resulting in a small distance between the insulating film and the cover plate, which makes it easy for explosion points to occur when the cover plate and the shell are welded.

[0004] Related technologies use heat shrinking to wrap an insulating film around the sidewalls of the electrode assembly, which can alleviate issues with film breakage and slippage during insertion into the battery case. However, to ensure uniform heat shrinkage, a tubular insulating film is required. During production, this tubular insulating film must be applied to the electrode assembly, but the relatively small opening in the insulating film results in low film application efficiency, significantly impacting battery cell production efficiency. Summary of the Invention

[0005] The present invention provides a film sleeve device for battery core assembly, which is used to solve the problem of low efficiency in sleeve-coating a tubular insulating film on an electrode group in the related art.

[0006] The present invention provides a film covering device for battery cell assembly, comprising: A shaping mechanism is used to shape the tubular insulating film so that the opening shape of the insulating film is adapted to the cross-sectional shape of the peripheral side wall of the pole group, and the shaped insulating film can move along the axial direction of the insulating film under the action of external pulling; The guide fixture includes an assembly portion and a guide portion, wherein the assembly portion has a first end and a second end opposite to each other, the first end being adapted to be assembled with one end of the electrode group, the second end being connected to the guide portion, and the guide portion being tapered away from the first end; a slot is provided at the first end of the assembly portion, into which one end of the electrode group can be inserted, and an avoidance groove is provided in the slot, which is adapted to accommodate the electrode tab of the electrode group; Wherein, when the insulating film moves along the axial direction, it can be sleeved to the outside of the pole group under the guidance of the guide part.

[0007] According to a film covering device for battery cell assembly provided by the present invention, the shaping mechanism includes: a blower for blowing air into the insulating film to expand the insulating film; The pressing plate assembly comprises a first pressing plate and a second pressing plate which are arranged opposite to each other and spaced apart. The first pressing plate and the second pressing plate are used for pressing on two opposite sides of the expanded insulating film respectively.

[0008] According to a film covering device for battery cell assembly provided by the present invention, the shaping mechanism further comprises: The suction cup assembly includes a first suction cup and a second suction cup that are arranged opposite to and spaced apart from each other. The first suction cup and the second suction cup are used to be respectively adsorbed on opposite sides of the expanded insulating film. The pressure plate assembly and the suction cup assembly are distributed in sequence along the moving direction of the insulating film.

[0009] According to a film sleeve device for cell assembly provided by the present invention, an assembly gap between the insulating film and the assembly portion is g1, and 0.2 mm ≤ g1 ≤ 10 mm.

[0010] According to a film sleeve device for cell assembly provided by the present invention, the depth of the slot is d1, 5mm≤d1≤50mm; and / or the assembly gap between the slot and the electrode group is g2, 0.05mm≤g2≤3mm.

[0011] According to a film sleeve device for cell assembly provided by the present invention, the depth of the slot is d1, the assembly gap between the slot and the electrode group is g2, and the film sleeve device satisfies at least one of the two conditions of 5mm≤d1≤50mm and 0.05mm≤g2≤3mm.

[0012] According to a casing device for assembling a battery cell provided by the present invention, the outer peripheral surface of the assembly portion includes multiple planes for surrounding the electrode group, and the outer peripheral surface of the guide portion includes multiple guide surfaces. The multiple guide surfaces are connected to the multiple planes in a one-to-one correspondence, and the guide surfaces are inclined relative to the planes connected thereto in a direction close to the guide portions.

[0013] According to a film covering device for battery cell assembly provided by the present invention, the guide surface has an inclination angle α relative to the plane connected thereto, and 3°≤α≤80°; According to a film covering device for cell assembly provided by the present invention, the dimension of the guide surface in the extension direction of the outer surface of the assembly portion is w1, 3mm≤w1≤1000mm; According to a membrane device for battery cell assembly provided by the present invention, the outer peripheral wall of the electrode group includes multiple side surfaces surrounding the electrode group, multiple planes and multiple side surfaces are arranged in parallel in a one-to-one correspondence, and the height difference between the corresponding planes and the side surfaces in a direction perpendicular to the planes is h, 0.5mm≤h≤20mm.

[0014] According to the present invention, a film covering device for cell assembly satisfies at least one of the following two conditions: the roughness of the outer peripheral surface of the guide portion is less than Ra3.2; and at least the assembly portion of the guide tool is a rubber part.

[0015] The wrapping device for battery cell assembly provided by the present invention comprises a shaping mechanism and a guiding fixture. The guiding fixture is used to assemble with the end of the electrode group, thereby providing the end of the electrode group with a tapered guide portion. During the wrapping operation, the shaping mechanism shapes the tubular insulating film, and the guiding fixture is assembled at the end of the electrode group. The insulating film, shaped by the shaping mechanism, can be moved axially by external pulling, and then guided by the guiding portion to be wrapped around the outside of the electrode group, achieving rapid wrapping and improving wrapping efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 It is a structural schematic diagram of the film sleeve device for battery cell assembly provided by the present invention.

[0018] Figure 2 It is an exploded schematic diagram of the guide tooling and the pole group in the film sleeve device for battery cell assembly provided by the present invention.

[0019] Figure 3 yes Figure 1 Cross-sectional view of the guide fixture and pole group assembly structure at AA.

[0020] Figure 4 yes Figure 1 A partial enlarged view of point C circled in the middle.

[0021] Figure 5 It is a structural schematic diagram of a guide tool in a film wrapping device for battery cell assembly provided by the present invention.

[0022] Figure 6 yes Figure 1Cross-sectional view of the guide fixture and pole group assembly structure at BB.

[0023] Reference numerals: 11. Shaping mechanism; 111. Press plate assembly; 111a. First press plate; 111b. Second press plate; 112. Suction cup assembly; 112a. First suction cup; 112b. Second suction cup; 12. Guide fixture; 121. Assembly portion; 1211. Plane; 122. Guide portion; 1221. Guide surface; 123. Slot; 1231. Slot wall; 124. Avoidance groove; 3. Insulating film; 4. Pole group; 41. Pole ear; 42. Side; X, length direction of the pole group; Y, width direction of the pole group; Z, thickness direction of the pole group. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0025] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "first" and "second" are for the purpose of clearly describing the numbering of product components and do not represent any substantial difference. The terms "installed", "connected" and "connected" 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 direct connection, or an indirect connection through an intermediate medium, or it can be a connection between the two components. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances. In addition, the meaning of "multiple" is two or more. "And / or" in the specification and claims means at least one of the connected objects, and the character " / " generally indicates that the related objects before and after are in an "or" relationship.

[0026] The following combination Figures 1-6 The present invention describes a film sleeve device for battery cell assembly.

[0027] like Figure 1As shown, the film-wrapping device for cell assembly provided by an embodiment of the present invention includes a shaping mechanism 11 and a guide tool 12. The shaping mechanism 11 is used to shape the tubular insulating film 3 so that the opening shape of the insulating film 3 is adapted to the cross-sectional shape of the peripheral side wall of the pole group 4, and the shaped insulating film 3 can move along the axial direction of the insulating film 3 under the action of external pulling. The guide tool 12 includes an assembly portion 121 and a guide portion 122. The assembly portion 121 has a first end and a second end opposite to each other, the first end is suitable for assembly with one end of the pole group 4, and the second end is connected to the guide portion 122, and the guide portion 122 is tapered in the direction away from the first end of the assembly portion 121. Wherein, when the insulating film 3 moves in the axial direction, it can be sleeved to the outside of the pole group 4 under the guidance of the guide portion 122.

[0028] The shaped insulating film 3 can be moved axially under the action of external pulling. This means that the shaping mechanism 11 adjusts the shape of the tubular insulating film 3 along the radial direction of the insulating film 3 without interfering with the axial movement of the insulating film 3. In actual production, the insulating film 3 can be pulled from the shaping mechanism 11 onto the electrode group 4 by machine or manually to complete the sheathing operation. The shaping mechanism 11 can be arranged vertically, and the electrode group 4 is placed below the shaping mechanism 11. The insulating film 3 is pulled from top to bottom to perform sheathing. After the sheathing is completed, the electrode group 4 sheathed with the insulating film 3 is transferred to a heat shrink device for heat shrinking.

[0029] See also Figure 2 The assembly portion 121 is used to assemble and connect with one end of the electrode group 4 in the longitudinal direction. When the two are assembled and connected, the assembly portion 121 and the guide portion 122 are distributed along the longitudinal direction of the electrode group 4. During the actual film covering operation, the longitudinal direction of the electrode group 4 is usually aligned with the movement direction of the insulating film 3 to facilitate smooth film covering.

[0030] The guide portion 122 tapers away from the assembly portion 121, i.e., the cross-section of the guide portion 122 gradually decreases away from the assembly portion 121. During the sheathing operation, the guide fixture 12 is first assembled with one end of the electrode assembly 4 through the assembly portion 121. Then, the end of the electrode assembly 4 equipped with the guide fixture 12 is directed toward the shaping mechanism 11. Under the action of external traction, the insulating film 3 moves along its axial direction toward the electrode assembly 4, sequentially sliding onto the guide portion 122, the assembly portion 121, and the electrode assembly 4. The tapered guide portion 122 allows the guide fixture 12 to slide smoothly into the insulating film 3, thereby allowing the insulating film 3 to be smoothly sheathed onto the outside of the electrode assembly 4, achieving efficient sheathing.

[0031] The sheathing device for cell assembly provided in an embodiment of the present invention comprises a shaping mechanism 11 and a guide fixture 12. The guide fixture 12 is configured to assemble with the end of the electrode group 4, providing the end of the electrode group 4 with a tapered guide portion 122. During the sheathing operation, the tubular insulating film 3 is shaped by the shaping mechanism 11, and the guide fixture 12 is assembled at the end of the electrode group 4. After being shaped by the shaping mechanism 11, the insulating film 3 can be moved axially by external traction, and then guided by the guide portion 122 to be sheathed onto the outside of the electrode group 4, achieving rapid sheathing and improving sheathing efficiency.

[0032] Alternatively, see Figure 1 The shaping mechanism 11 includes a fan (not shown) and a pressure plate assembly 111. The fan is used to blow air into the insulating film 3, causing the insulating film 3 to expand. The pressure plate assembly 111 includes a first pressure plate 111a and a second pressure plate 111b, which are spaced apart and opposed to each other. The first pressure plate 111a and the second pressure plate 111b are respectively adapted to be pressed against opposite sides of the expanded insulating film 3.

[0033] Specifically, a shaping channel is formed between the first pressing plate 111a and the second pressing plate 111b for the axial movement of the insulating film 3. During the sleeve operation, the electrode group 4 is located at the outlet side of the shaping channel. The shaping channel can be arranged in a vertical direction. The expanded insulating film 3 moves from top to bottom under the action of external traction and is shaped as it passes through the first pressing plate 111a and the second pressing plate 111b. During the removal process, it is simultaneously sleeved onto the electrode group 4. The number of pressing plate assemblies 111 can be one or more, and multiple pressing plate assemblies 111 are arranged at intervals along the movement direction of the insulating film 3. The specific number is determined by the length of the insulating film 3 and the length of the pressing plate.

[0034] Optionally, the first pressing plate 111a and the second pressing plate 111b can move closer to and farther from each other. During the film covering operation, the first pressing plate 111a and the second pressing plate 111b are first moved away from each other to allow the expanded insulating film 3 to move between the first pressing plate 111a and the second pressing plate 111b. The first pressing plate 111a and the second pressing plate 111b are then moved closer to a set distance to reshape the insulating film 3.

[0035] It should be noted that this embodiment is not limited to shaping the insulating film 3 by the fan and pressure plate assembly 111. For example, the shaping mechanism 11 includes two opposing support plates that can extend into the insulating film 3, and the insulating film 3 is shaped by moving the two support plates away from each other.

[0036] Furthermore, the shaping mechanism 11 includes a suction cup assembly 112. The suction cup assembly 112 comprises a first suction cup 112a and a second suction cup 112b, which are positioned opposite and spaced apart from each other. The first suction cup 112a and the second suction cup 112b are configured to adhere to opposite sides of the expanded insulating film 3. The pressure plate assembly 111 and the suction cup assembly 112 are sequentially arranged along the direction of movement of the insulating film 3.

[0037] It will be appreciated that during the film covering operation, the insulating film 3 removed from the pressure plate assembly 111 passes through the suction cup assembly 112, passing between the first suction cup 112a and the second suction cup 112b before being covered with the electrode assembly 4. The first suction cup 112a and the second suction cup 112b hold the opposing sides of the insulating film 3, maintaining the shape of the opening of the insulating film 3 stable, facilitating smoother covering of the electrode assembly 4.

[0038] The first suction cup 112a and the second suction cup 112b are capable of moving closer to and further away from each other. During the film covering operation, the first suction cup 112a and the second suction cup 112b are first moved away from each other so that the insulating film 3 removed from the pressure plate assembly 111 can be smoothly moved between the first suction cup 112a and the second suction cup 112b. The first suction cup 112a and the second suction cup 112b are then moved closer to each other to a predetermined distance to fix the opening shape of the insulating film 3.

[0039] See also Figure 4 In some embodiments of the present invention, the assembly gap between the insulating film 3 and the assembly portion 121 is g1, where g1 ≥ 0.2 mm. A smaller g1 can make it difficult to insert the guide fixture 12. For example, if the electrode assembly 4 has a rectangular cross-section, the inner width of the rectangular opening of the shaped insulating film 3 is M1 and the inner length is L1. The width of the assembly portion 121 is M2 and the length is L2. M1-M2 ≥ 0.4 mm, and L1-L2 ≥ 0.4 mm.

[0040] Furthermore, g1 ≤ 10 mm. A larger g1 indicates a longer circumference of the insulating film 3, which can easily lead to poor thickness uniformity after heat shrinkage and loose wrapping, making it prone to slippage when inserted into the housing. Optionally, g1 can be 0.4 mm, 0.8 mm, 1.2 mm, 2 mm, 5 mm, or 8 mm.

[0041] See also Figure 4 In some embodiments of the present invention, a slot 123 is provided at the first end of the assembly portion 121, and one end of the electrode group 4 can be inserted into the slot 123. The assembly portion 121 and the electrode group 4 can be conveniently assembled by plugging together.

[0042] Furthermore, the depth of slot 123 is d1, where 5mm≤d1≤50mm. If the insertion depth is too small, the insertion may be loose, and the guide tool 12 may easily fall during operation. If the insertion depth is too large, the guide tool 12 may be increased in size and weight, increasing material costs and causing operational inconvenience. Optionally, the value of d1 may be 5mm, 10mm, 20mm, 40mm, or 50mm.

[0043] In some embodiments of the present invention, the assembly clearance between the slot 123 and the electrode group 4 is g2, with a range of 0.05 mm ≤ g2 ≤ 3 mm. If g2 is too small, insertion may become difficult; if g2 is too large, insertion may become loose, and the guide fixture 12 may easily slip off the electrode group 4. For example, if the cross-section of the electrode group 4 is rectangular, the dimension of the slot 123 in the thickness direction of the electrode group 4 is M3, and the dimension of the slot 123 in the width direction of the electrode group 4 is L3. The thickness of the electrode group 4 is M4, and the width of the electrode group 4 is L4. 0.1 mm ≤ M3 - M4 ≤ 6 mm, and 0.1 mm ≤ L3 - L4 ≤ 6 mm.

[0044] In some embodiments of the present invention, 5 mm ≤ d1 ≤ 50 mm, and 0.05 mm ≤ g2 ≤ 3 mm, which can ensure reliable and convenient plugging of the guide tooling 12 and the electrode group 4 without increasing the volume and weight of the guide tooling 12 .

[0045] like Figure 3-Figure 6 As shown, in some embodiments of the present invention, a relief groove 124 is provided within the slot 123. The relief groove 124 is adapted to accommodate the tab 41 of the electrode assembly 4. Specifically, the electrode assembly 4 includes a body and a tab 41. The body has an end surface at one end in the longitudinal direction of the electrode assembly 4, and the tab 41 protrudes from the end surface. The slot 123 is configured to be plugged into the body of the electrode assembly 4. The relief groove 124 within the slot 123 can accommodate the tab 41 to prevent the guide tool 12 from crushing the tab 41.

[0046] The avoidance groove 124 is recessed at least in the bottom of the slot 123. When the assembly portion 121 is assembled with the electrode assembly 4, the bottom of the slot 123 limits the insertion depth of the electrode assembly 4, defining a cavity between the end surface of the electrode assembly and the bottom of the avoidance groove 124 that can accommodate the electrode tab 41. The width of the electrode tab 41 is consistent with the width of the electrode assembly 4. Typically, the width of the electrode tab 41 is smaller than the width of the electrode assembly 4. Therefore, the avoidance groove 124 is also smaller than the slot 123 in the width direction of the electrode assembly 4.

[0047] Furthermore, in the thickness direction of the pole group 4, the size of the avoidance groove 124 is larger than the size of the slot 123. Figure 5 and Figure 6The slot 123 has two slot walls 1231 arranged opposite to each other in the thickness direction of the pole group 4, and the avoidance groove 124 is recessed in the bottom of the slot 123 and the two slot walls 1231. This can increase the avoidance space of the avoidance groove 124 in the thickness direction of the pole group 4 to avoid the pole ear 41 from scratching the assembly part 121 during the assembly process of the guide tooling 12 and the pole group 4.

[0048] See also Figure 2 and Figure 4 In some embodiments of the present invention, the outer circumference of the assembly portion 121 includes a plurality of flat surfaces 1211 for surrounding the electrode group 4, and the outer circumference of the guide portion 122 includes a plurality of guide surfaces 1221. The plurality of guide surfaces 1221 are connected to the plurality of flat surfaces 1211 in a one-to-one correspondence, and the guide surfaces 1221 are inclined relative to the flat surfaces 1211 to which they are connected, toward the guide portion 122.

[0049] After the assembly portion 121 is assembled with the electrode assembly 4, the multiple flat surfaces 1211 of the assembly portion 121 surround the outside of the electrode assembly 4, allowing the insulating film 3 to slide through the outer peripheral surface of the assembly portion 121 to the outside of the electrode assembly 4. Optionally, the outer peripheral surface of the assembly portion 121 is contoured to the peripheral sidewall of the electrode assembly 4, which includes multiple side surfaces 42 surrounding the electrode assembly 4. The multiple flat surfaces 1211 of the assembly portion 121 are arranged in parallel with the multiple side surfaces 42 of the electrode assembly 4 in a one-to-one correspondence. Each guide surface 1221 of the guide portion 122 is inclined relative to the flat surface 1211 connected thereto toward the guide portion 122, causing the guide portion 122 to gradually taper away from the assembly portion 121.

[0050] For example, the outer sidewall of the rectangular pole group 4 includes four side surfaces 42 surrounding the pole group 4. The outer peripheral surface of the mounting portion 121 includes four flat surfaces 1211 surrounding the pole group 4. These four flat surfaces 1211 are arranged parallel to the four side surfaces 42 of the pole group 4 in a one-to-one correspondence. The outer peripheral surface of the guide portion 122 includes four guide surfaces 1221, which are connected to the four flat surfaces 1211 in a one-to-one correspondence.

[0051] It should be noted that the guide surface 1221 is not limited to the inclined surface described in the above embodiment. For example, the guide surface 1221 may also be an arc-shaped surface that bulges away from the guide portion 122 .

[0052] See also Figure 4 In some embodiments of the present invention, the guide surface 1221 has an inclination angle α relative to the plane 1211 to which it is connected, with a range of 3°≤α≤80°. If the inclination angle is too small, it is difficult to quickly insert the guide tool 12 into the insulating film 3. If the inclination angle is too large, the insulating film 3 may easily hit the wall, hindering the smooth sliding of the insulating film 3 toward the electrode group 4. Optionally, α can be 10°, 40°, 45°, or 70°.

[0053] See also Figure 4 In some embodiments of the present invention, the dimension of the guide surface 1221 in the extension direction of the outer surface of the assembly portion 121 is w1, 3mm≤w1≤1000mm. In which, when the assembly portion 121 is assembled and connected to one end of the pole group 4 in the length direction, the extension direction of the outer surface of the assembly portion 121 is the length direction of the pole group 4. If the dimension of the guide surface 1221 in this direction is too small, the guide area will be too small, and it will not play a good role in guiding the deformation of the pipe mouth of the insulating film 3 and the sliding toward the pole group 4; if the dimension of the guide surface 1221 in this direction is too large, the volume and weight of the guide tooling 12 will be increased, which will increase the material cost and bring inconvenience to the operation. Optionally, w1 takes a value of 100mm, 300mm, 500mm or 800mm, etc.

[0054] See also Figure 4 In some embodiments of the present invention, the outer peripheral wall of the pole group 4 includes a plurality of side surfaces 42 surrounding the pole group 4, and the plurality of planes 1211 of the assembly portion 121 are arranged in parallel with the plurality of side surfaces 42 of the pole group 4 in a one-to-one correspondence. The height difference between the corresponding planes 1211 and the side surfaces 42 in a direction perpendicular to the plane 1211 is h, and 0.5mm≤h≤20mm. If h is too small, the outer peripheral wall of the pole group 4 is not flat enough, which may easily cause the insulating film 3 to get stuck when sliding on the outside of the pole group 4, making it difficult to insert. If h is too large, it means that the circumference of the insulating film 3 is also too large, which may easily cause the thickness uniformity of the insulating film 3 after heat shrinkage to be poor, and the wrapping is not tight, which may easily cause slippage when inserting into the shell. Optionally, h is 1mm, 5mm, 10mm or 15mm, etc.

[0055] Furthermore, the roughness of the outer peripheral surface of the guide portion 122 is less than Ra3.2. If the roughness is too large, the film covering failure or film covering defect will easily occur under the production line rhythm, causing the equipment to alarm.

[0056] Optionally, at least the assembly portion 121 of the guide fixture 12 is a rubber member. For example, the assembly portion 121 can be made of a soft rubber material such as fluororubber or EPDM. The rubber assembly portion 121 allows for flexible contact with the electrode assembly 4, preventing scratches during assembly. The guide portion 122 can also be a rubber member, with the guide portion 122 and assembly portion 121 integrally formed. Alternatively, the guide portion 122 can be a hard plastic member, which facilitates obtaining a smoother guide surface 1221.

[0057] The ranges of values ​​for α, g1, and h defined in the above embodiments were tested using the following experimental process, yielding the experimental data shown in Table 1. Experimental process: Using guide fixtures 12 corresponding to different values ​​of α, g1, and h, multiple pole groups 4 were sheathed. A traction mechanism was used to pull the insulating film 3 along its axial direction for sheathing. A force sensor was installed in the traction mechanism to detect the traction force during sheathing. If a traction force greater than 50N was detected, indicating difficulty in sheathing the insulating film 3, the device would sound an alarm. After sheathing, the insulating film 3 was heat-shrunk, and the thickness uniformity of the heat-shrunk insulating film 3 was measured. The heat-shrunk pole groups 4 were then placed into shells to test the difficulty of insertion.

[0058] Table 1: Film handling test of guide fixtures for different α, g1 and h values

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A film covering device for battery cell assembly, characterized in that: include: A shaping mechanism is used to shape the tubular insulating film so that the opening shape of the insulating film is adapted to the cross-sectional shape of the peripheral side wall of the pole group, and the shaped insulating film can move along the axial direction of the insulating film under the action of external pulling; The guide fixture includes an assembly portion and a guide portion, wherein the assembly portion has a first end and a second end opposite to each other, the first end being adapted to be assembled with one end of the electrode group, the second end being connected to the guide portion, and the guide portion being tapered away from the first end; a slot is provided at the first end of the assembly portion, into which one end of the electrode group can be inserted, and an avoidance groove is provided in the slot, which is adapted to accommodate the electrode tab of the electrode group; Wherein, when the insulating film moves along the axial direction, it can be sleeved to the outside of the pole group under the guidance of the guide part.

2. The film covering device for battery cell assembly according to claim 1, characterized in that: The shaping mechanism comprises: a blower for blowing air into the insulating film to expand the insulating film; The pressing plate assembly comprises a first pressing plate and a second pressing plate which are arranged opposite to each other and spaced apart. The first pressing plate and the second pressing plate are used for pressing on two opposite sides of the expanded insulating film respectively.

3. The film covering device for battery cell assembly according to claim 2, characterized in that: The shaping mechanism also includes: The suction cup assembly includes a first suction cup and a second suction cup that are arranged opposite to and spaced apart from each other. The first suction cup and the second suction cup are used to be respectively adsorbed on opposite sides of the expanded insulating film. The pressure plate assembly and the suction cup assembly are distributed in sequence along the moving direction of the insulating film.

4. The film covering device for battery cell assembly according to claim 1, characterized in that: An assembly gap between the insulating film and the assembly portion is g1, 0.2 mm ≤ g1 ≤ 10 mm.

5. The film covering device for battery cell assembly according to claim 1, characterized in that: The depth of the slot is d1, the assembly gap between the slot and the electrode group is g2, and the membrane device satisfies at least one of the two conditions of 5mm≤d1≤50mm and 0.05mm≤g2≤3mm.

6. The film covering device for battery cell assembly according to claim 1, characterized in that: The outer peripheral surface of the assembly portion includes multiple planes for surrounding the pole group, and the outer peripheral surface of the guide portion includes multiple guide surfaces. The multiple guide surfaces are connected to the multiple planes in a one-to-one correspondence, and the guide surfaces are inclined relative to the planes connected thereto toward the direction close to the guide portion.

7. The film covering device for battery cell assembly according to claim 6, characterized in that: The guide surface has an inclination angle α relative to the plane connected thereto, and the angle is 3°≤α≤80°.

8. The film covering device for battery cell assembly according to claim 6, characterized in that: A dimension of the guide surface in an extending direction of the outer surface of the fitting portion is w1, 3 mm ≤ w1 ≤ 1000 mm.

9. The film covering device for battery cell assembly according to claim 6, characterized in that: The outer peripheral wall of the pole group includes multiple side surfaces surrounding the pole group, and the multiple planes and the multiple side surfaces are arranged in parallel in a one-to-one correspondence. The height difference between the corresponding planes and the side surfaces in a direction perpendicular to the planes is h, 0.5mm≤h≤20mm.

10. The film covering device for battery cell assembly according to claim 1, characterized in that: The film covering device satisfies at least one of the following two conditions: the roughness of the outer peripheral surface of the guide portion is less than Ra3.2; and at least the assembly portion of the guide fixture is a rubber member.

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