An insulating film, a cell wrapping structure, an assembly method and a secondary battery

Abstract

The present invention provides an insulating film, a cell wrapping structure, an assembly method and a secondary battery, which include two film bodies and a connecting film connected between the two film bodies. The film bodies are used to wrap a bare cell; avoidance holes are respectively formed at both ends of the connecting film in the length direction, and the avoidance holes are used for a battery adapter plate to pass through; a first protective film is arranged on one side of the avoidance hole facing the middle of the connecting film, and the first protective film is used to paste on the side of the battery adapter plate away from the tab of the bare cell; a second protective film is arranged on the top surface of the side of the avoidance hole away from the first protective film, and the second protective film is used to paste on the surface of the tab of the bare cell and the surface of the battery adapter plate away from the pole column. The insulating film disclosed by the present invention can be used for wrapping the bare cell and also for pasting glue on the tabs of the bare cell, reducing the glue pasting step, optimizing the wrapping form, and providing comprehensive protection for the bare cell and the tab area.

Description

Technical Field

[0001] The present invention relates to the technical field of battery manufacturing, and in particular, to an insulating film, a cell wrapping structure, an assembly method, and a secondary battery. Background Art

[0002] When manufacturing a lithium battery cell, welding needs to be performed on the tab. After the welding is completed, solder joints will be generated on the tab. Moreover, since the protruding height position of the tab may not be suitable for our requirements, the tab generally needs to be bent. In this case, short circuits are likely to occur. Therefore, insulating tape needs to be pasted on the welding position, and insulating tape needs to be pasted on both sides of the tab.

[0003] Since insulating tape needs to be pasted on the front and back of the positive and negative tabs of the cell, a total of 4 insulating tape pasting operations are required. In order to improve the space utilization rate of the pasting mechanism, generally two stations are used for pasting: one for pasting insulating tape on the front and back of the positive electrode; the other for pasting insulating tape on the front and back of the negative electrode. Thus, a mechanism for simultaneously pasting insulating tape on both sides of the lithium battery cell tab is required. In addition, after the production of the bare cell by stacking or winding is completed, wrapping with an insulating film is an essential process, which plays a role in protecting and insulating the cell. In the prior art, generally, after the cell tabs are welded, insulating tape is pasted, and then after the insulating tape is pasted, the insulating film is wrapped. For example, in the patent with the publication number CN207587896 U, the disclosed insulating film is only for realizing the wrapping operation of the bare cell, and separate insulating tape pasting operations on the tabs are required before wrapping. The above-mentioned insulating tape pasting and wrapping steps are cumbersome, and the production efficiency of lithium batteries is relatively low. Summary of the Invention

[0004] In view of this, the present invention provides an insulating film, a cell wrapping structure, an assembly method, and a secondary battery, which can be used as an insulating film and can also be used for pasting insulating tape, reducing the insulating tape pasting steps, optimizing the wrapping form, and providing comprehensive protection for the bare cell and the tab area.

[0005] The technical solution of the present invention is realized as follows:

[0006] On the one hand, the present invention provides an insulating film, which includes two film bodies and a connecting film connected between the two film bodies. The film bodies are used to wrap the bare cell;

[0007] Avoidance holes are respectively opened at both ends in the length direction of the connecting film, and the avoidance holes are used for the battery connection piece to pass through;

[0008] A first protective film is arranged on one side of the avoidance hole facing the middle of the connecting film, and the first protective film is used to paste on the side of the battery connection piece away from the bare cell tab;

[0009] On the side of the avoidance hole away from the first protective film, a second protective film is provided on the top surface, and the second protective film is used to be pasted on the surface of the bare cell tab and the surface of the battery adapter away from the pole column.

[0010] Based on the above technical solution, preferably, the area of the first protective film is greater than or equal to the area of the welding region of the tab on the battery adapter.

[0011] Furthermore, preferably, a first double-sided tape is provided on the front surface of the first protective film, and the first double-sided tape is used to be pasted on the surface of the battery adapter away from the tab welding region.

[0012] Based on the above technical solution, preferably, the area of the second protective film is greater than or equal to the total area of the welding of the tab and the pole column on the battery adapter.

[0013] Furthermore, preferably, a second double-sided tape is provided on the back surface of the second protective film, and the second double-sided tape is used to bond with the surface of the tab and the side of the battery adapter away from the pole column.

[0014] On the other hand, the present invention provides a cell encapsulation structure, including a top cover, a battery adapter, a bare cell and the insulating film. Two bare cells are provided and are respectively laid flat on the film body. The tabs of the two bare cells are arranged opposite to each other. The tabs on the bare cells are welded on the front surface of the battery adapter. The battery adapter is located at the avoidance hole. The first protective film is pasted on the surface of the battery adapter away from the tab welding region. The top cover is arranged on the bottom surface of the connecting film. The pole column on the top cover is welded to one end of the bottom surface of the battery adapter away from the first protective film. The second protective film is pasted on the surface of the tab and the side of the battery adapter away from the pole column. The film body wraps the outer surface of the bare cell.

[0015] Based on the above technical solution, preferably, on both sides of the top cover in the length direction and facing the connecting film, stop posts are symmetrically arranged. The distance between the two stop posts is greater than or equal to the length of the connecting film. A stop hole connected to the stop posts is opened at one end of the second protective film away from the avoidance hole.

[0016] Furthermore, preferably, a plurality of stop grooves are provided on one side of the stop post facing the length direction of the top cover. The plurality of stop grooves are arranged at intervals along the axial direction of the stop post. The stop hole is used to be clamped on the stop groove.

[0017] In the third aspect, the present invention discloses an assembly method of a cell encapsulation structure, including the following steps:

[0018] S1. Ultrasonically weld the tabs of the bare cell and the battery adapter;

[0019] S2. Lay the insulating film flat, place the bare cell flat on the film body, and place the battery adapter in the avoidance hole of the connecting film;

[0020] S3. Paste the first protective film on the surface of the battery adapter away from the welding area of the tab.

[0021] S4. Place the top cover on the side of the connecting film away from the bare cell, and laser-weld the pole column on the top cover and the battery adapter.

[0022] S5. Paste the second protective film on the surface of the tab and the side of the battery adapter away from the pole column.

[0023] S6. Wrap the film body around the outer surface of the bare cell.

[0024] The present invention also discloses a secondary battery, including a housing and the cell wrapping structure described above. Two bare cells are arranged side by side in the housing, and the cover plate is hermetically connected to the open end of the housing.

[0025] The present invention has the following beneficial effects compared with the prior art:

[0026] (1) For the insulating film disclosed in the present invention, by respectively arranging film bodies on both sides of the connecting film, after the tabs of the bare cell are welded to the battery adapter, the bare cell can be horizontally placed on the film body, and the film body can wrap the bare cell. By arranging avoidance holes on the connecting film, the battery adapter can pass through. By respectively arranging the first protective film and the second protective film on both sides in the length direction of the avoidance hole, the first protective film can be pasted on the side of the battery adapter away from the tabs of the bare cell. After the battery adapter is welded to the pole column on the top cover, the second protective film can be pasted on the surface of the tabs of the bare cell and the side of the battery adapter away from the pole column, so as to realize that the insulating film can be used for wrapping the bare cell and can also be used for pasting glue on the tabs of the bare cell, reducing the glue-pasting steps, optimizing the wrapping form, and providing comprehensive protection for the bare cell and the tab area.

[0027] (2) Before the battery adapter is welded to the pole column, the first protective film can protect the surface of the battery adapter away from the welding area of the tab. After the battery adapter is welded to the pole column, the second protective film can protect the tabs and the side of the battery adapter away from the pole column. The first protective film and the second protective film can comprehensively cover the tabs and the battery adapter, minimizing the generation of welding slag and avoiding pollution and short circuit caused by welding slag.

[0028] (3) By symmetrically arranging stop posts at both ends of the top cover in the opposite direction of its length, and arranging stop holes at one end of the second protective film away from the avoidance hole, by folding the second protective film outward along the length direction of the avoidance hole and sleeving the stop holes on the stop posts, the position of the second protective film outside the avoidance hole can be restricted, avoiding the second protective film from blocking the avoidance hole and facilitating the welding of the top surface of the battery adapter and the pole column.

[0029] (4) By providing a plurality of stop grooves on one side of the stop post in the length direction towards the top cover, and arranging the plurality of stop grooves at intervals along the axial direction of the stop post, the second protective film can be snap-fitted into the stop grooves through the stop holes, preventing the stop holes from detaching from the stop post during the welding vibration of the battery adapter piece and the pole column, thus affecting the normal progress of welding. Brief Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 Schematic three-dimensional structure diagram of the insulating film disclosed in the present invention;

[0032] Figure 2 Schematic first-perspective assembly structure diagram of the insulating film and the bare battery cell disclosed in the present invention;

[0033] Figure 3 Schematic second-perspective assembly structure diagram of the insulating film and the bare battery cell disclosed in the present invention;

[0034] Figure 4 Schematic structure diagram of the bare battery cell, insulating film and top cover disclosed in the present invention;

[0035] Figure 5 For Figure 4 Local enlarged view at A in

[0036] Figure 6 Schematic three-dimensional structure diagram of the bare battery cell coating structure disclosed in the present invention;

[0037] Figure 7 Top view of the bare battery cell coating structure disclosed in the present invention;

[0038] Figure 8 For Figure 7 Cross-sectional view taken along line B-B in

[0039] Figure 9 For Figure 8 Local enlarged view at C in

[0040] Reference Numerals:

[0041] 1, insulating film; 11, film body; 12, connecting film; 120, avoidance hole; 13, first protective film; 14, second protective film; 2, top cover; 3, battery adapter piece; 4, bare battery cell; 41, tab; 21, pole column; 22, stop post; 141, stop hole; 221, stop groove. Detailed implementation mode

[0042] Next, in combination with the implementation mode of the present invention, the technical solutions in the implementation mode of the present invention will be clearly and completely described. Obviously, the described implementation mode is only a part of the implementation modes of the present invention, rather than all the implementation modes. Based on the implementation modes in the present invention, all other implementation modes obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0043] As Figure 1 shown, in combination with Figures 2-3 , an insulating film 1 is disclosed in an embodiment of the present invention. The insulating film 1 in this embodiment is preferably a Mylar film. The insulating film 1 includes two film bodies 11 and a connecting film 12 connected between the two film bodies 11. The film body 11 is used to wrap the bare battery cell 4. The insulating film 1 in this embodiment is applicable to the double battery cell wrapping operation.

[0044] In the prior art, the connecting film 12 is usually used to avoid the welding positions of the electrode tab 41 and the electrode post 21, and at the same time to provide a liquid injection channel and an explosion-proof valve channel. The existing insulating film 1 usually only realizes the wrapping of the bare battery cell 4. Since some welding slag will be generated after the electrode tab 41 is welded to the battery connection piece 3 and accumulates between the electrode tab 41 and the battery connection piece 3, after the welding of the electrode tab 41 and the battery connection piece 3 is completed, it is necessary to wrap the welding area of the electrode tab 41 to prevent the welding slag from flowing out and entering the bare battery cell 4 to cause pollution or short circuit.

[0045] Generally, the electrode tab 41 is welded at one end in the length direction of the battery connection piece 3. After the welding of the electrode tab 41 on the battery connection piece 3 is completed, a protective film is usually first pasted on the surface of the welding area of the electrode tab 41. The protective film here can prevent the welding slag from leaking from the gap between the electrode tab 41 and the battery connection piece 3. At the same time, a protective film is pasted on the side of the battery connection piece 3 away from the electrode tab 41, and it is ensured that the protective film does not cover the welding area of the battery connection piece 3 and the electrode post 21. This is to avoid the accumulation of welding slag on the side of the battery connection piece 3 away from the electrode post 21 during the welding of the electrode tab 41 and the battery connection piece 3. Before the welding of the electrode post 21, the other end in the length direction of the battery connection piece 3 is not laminated. When the electrode post 21 on the top cover 2 is welded to the battery connection piece 3, a protective film is pasted on the side of the battery connection piece 3 away from the electrode post 21 to avoid the pollution of the welding slag and its leakage into the bare battery cell 4 to cause a short circuit.

[0046] In the prior art, after the welding of the electrode tab 41 is completed, glue is applied, and then the insulating film 1 is wrapped after the glue is applied. The above steps of applying glue and wrapping the film are cumbersome, and the production efficiency of lithium batteries is relatively low.

[0047] To this end, in this embodiment, avoidance holes 120 are respectively formed at both ends of the connecting film 12 in the length direction. The avoidance holes 120 are used for the battery adapter piece 3 to pass through. After the tab 41 of the bare battery cell 4 is welded to the battery adapter piece 3, the bare battery cell 4 can be horizontally placed on the film body 11. The film body 11 can wrap the bare battery cell 4, and the avoidance holes 120 can allow the battery adapter piece 3 to pass through, which is convenient for welding with the pole column 21 on the top cover 2.

[0048] In order to realize that the insulating film 1 applies glue to the tab 41, in this embodiment, a first protective film 13 is arranged on one side of the avoidance hole 120 facing the middle of the connecting film 12. The first protective film 13 is used for pasting on the side of the battery adapter piece 3 away from the tab 41 of the bare battery cell 4. During the welding process of the tab 41 and the battery adapter piece 3, the generated welding slag will adhere to the side of the battery adapter piece 3 away from the pole column 21. The first protective film 13 can cover the welding slag on the side of the battery adapter piece 3 away from the pole column 21. It can prevent the welding slag from causing pollution on the battery adapter piece 3 or leaking into the bare battery cell 4 to cause a short circuit.

[0049] On the top surface of the side of the avoidance hole 120 away from the first protective film 13, a second protective film 14 is arranged. The second protective film 14 is used for pasting on the surface of the tab 41 of the bare battery cell 4 and the surface of the battery adapter piece 3 away from the pole column 21. After the battery adapter piece 3 is welded to the pole column 21 on the top cover 2, there will be welding slag on the side of the battery adapter piece 3 away from the pole column 21. At the same time, welding slag will also be generated after the tab 41 is welded to the battery adapter piece 3. At this time, through the second protective film 14, it can directly cover the surface of the tab 41 and the side of the battery adapter piece 3 away from the pole column 21, preventing the welding slag from leaking into the bare battery cell 4 during the subsequent process of forming a battery with the bare battery cell 4, causing pollution or short circuit.

[0050] In addition, in this embodiment, only by the first protective film 13 and the second protective film 14, the full gluing of the welding areas of the tab 41, the pole column 21 and the battery adapter piece 3 can be completed. The gluing steps are reduced and the process is simple. At the same time, after the gluing of the tab 41 is completed, the wrapping of the bare battery cell 4 is immediately completed. Compared with the prior art, there is no need to separately apply glue to the tab 41 through an insulating tape. The insulating film 1 in this embodiment can be used to wrap the bare battery cell 4 and also apply glue to the tab 41 of the bare battery cell 4, reducing the gluing steps, optimizing the wrapping form, providing comprehensive protection for the bare battery cell 4 and the tab 41 area, and greatly improving the operation efficiency of gluing and wrapping the bare battery cell.

[0051] As some preferred embodiments, in order to enable the first protective film 13 to cover a larger area of the surface of the battery adapter piece 3 away from the pole column 21. In this embodiment, the area of the first protective film 13 is set to be greater than or equal to the area of the welding area of the tab 41 on the battery adapter piece 3. Thus, it can be realized that the first protective film 13 can cover more welding slag on the surface of the battery adapter piece 3, reducing the leakage of welding slag.

[0052] In some embodiments, when cutting the avoidance hole 120 on the connection film 12, the first protective film 13 can be directly cut out. The width of the first protective film 13 is adapted to the width of the avoidance hole 120, and the length of the first protective film 13 is 1 mm - 2 mm greater than the length of the welding area of the tab 41. Thus, when the bare battery cell 4 is placed on the insulating film 1, under the mutual cooperation of the connection film 12 and the first protective film 13, after the first protective film 13 is attached to the battery adapter plate 3, it coincides with the incision in the width direction of the avoidance hole 120, thereby realizing the full-glue operation.

[0053] In order to enable the first protective film 13 to be firmly adhered to the surface of the battery adapter plate 3, in this embodiment, a first double-sided tape (not shown in the figure) is provided on the front surface of the first protective film 13. The area of the first double-sided tape is equal to the area of the first protective film 13. After the tab 41 is welded to the battery adapter plate 3, the two lying bare battery cells 4 are placed on the insulating film 1, the first protective film 13 is folded to the lower part of the avoidance hole 120, the backing adhesive on the first double-sided tape is torn off, and then the first protective film 13 is adhered to the side of the battery adapter plate 3 away from the tab 41. At this time, the two sides in the width direction of the first protective film 13 coincide with the two sides in the width direction of the avoidance hole 120, realizing the combination of the first protective film 13 and the connection film 12 into one body, and can completely cover the bottom surface of the battery adapter plate 3 corresponding to the welding area of the tab 41 for comprehensive protection. At the same time, the opening area of the avoidance hole 120 is just adapted to the area of the terminal post 21, facilitating the welding of the terminal post 21 to the battery adapter plate 3 and avoiding the leakage of welding slag from the avoidance hole 120.

[0054] During the actual operation process, the top cover 2 is horizontally placed on the side of the connection film 12 away from the bare battery cell 4, and the terminal post 21 on the top cover 2 is welded to the battery adapter plate 3 through the avoidance hole 120. Welding slag will be generated during the welding process of the battery adapter plate 3 and the terminal post 21. At the same time, since welding slag will be generated in the welding area of the tab 41 and the battery adapter plate 3 during the previous welding of the tab 41 to the battery adapter plate 3, in order to prevent the above-mentioned welding slag from falling into the bare battery cell 4 and causing a short circuit after the two bare battery cells 4 are folded and stacked.

[0055] In this embodiment, the second protective film 14 is adhered to the surface of the tab 41 and the side of the battery adapter 3 away from the terminal 21 simultaneously. Preferably, the area of the second protective film 14 is greater than or equal to the sum of the welding areas of the tab 41 and the terminal 21 on the battery adapter 3. This is to enable the second protective film 14 to cover more of the surfaces of the tab 41 and the battery adapter 3. In some embodiments, the area of the second protective film 14 can be equal to the area of the avoidance hole 120. In this way, after the second protective film 14 is adhered, it can coincide with the avoidance hole 120. In some other embodiments, since the tab 41 has a certain thickness on the battery adapter 3, the second protective film 14 is not flat after being adhered. By making the area of the second protective film 14 larger than the area of the avoidance hole 120, the second protective film 14 can completely cover the avoidance hole 120. With the mutual cooperation of the connecting film 12, the first protective film 13, and the second protective film 14, the whole formed by the battery adapter 3 and the tab 41 is completely covered on the upper and lower surfaces. In this way, it can prevent the welding slag generated during the welding process from leaking and causing a short circuit to the bare cell 4.

[0056] To enable the second protective film 14 to be firmly adhered to the surface of the battery adapter 3 and the tab 41, in this embodiment, a second double-sided tape (not shown in the figure) is provided on the back of the second protective film 14. During the actual operation, the second protective film 14 is pre-bonded to one end of the avoidance hole 120 away from the first protective film 13. After the welding of the terminal 21 and the battery adapter 3 is completed, by tearing off the back glue of the second double-sided tape, the second protective film 14 is directly adhered horizontally to the surfaces of the tab 41 and the battery adapter 3, and the second protective film 14 is made to cover the connecting film 12 surface outside the avoidance hole 120, so as to cooperate with the first protective film 13 to achieve the full adhesive operation on the upper and lower surfaces of the tab 41 and the battery adapter 3.

[0057] The present invention also discloses a cell encapsulation structure. Referring to the attached Figures 4-9 figure, it includes a top cover 2, a battery adapter 3, a bare cell 4, and the above-disclosed insulating film 1. Two bare cells 4 are provided and are respectively laid flat on the film body 11. The tabs 41 of the two bare cells 4 are arranged opposite to each other. The tabs 41 on the bare cells 4 are welded to the front surface of the battery adapter 3. The battery adapter 3 is located at the avoidance hole 120. The first protective film 13 is adhered to the surface of the battery adapter 3 away from the welding area of the tab 41. The top cover 2 is arranged on the bottom surface of the connecting film 12. The terminal 21 on the top cover 2 is welded to one end of the bottom surface of the battery adapter 3 away from the first protective film 13. The second protective film 14 is adhered to the surface of the tab 41 and the side of the battery adapter 3 away from the terminal 21. The film body 11 is wrapped around the outer surface of the bare cell 4.

[0058] With the above technical solution, before the battery adapter tab 3 is welded to the pole column 21, the first protective film 13 can protect the surface of the battery adapter tab 3 away from the welding area of the tab 41. After the battery adapter tab 3 is welded to the pole column 21, the second protective film 14 can protect the tab 41 and the side of the battery adapter tab 3 away from the pole column 21. The first protective film 13 and the second protective film 14 can comprehensively cover the tab 41 and the battery adapter tab 3, minimizing the generation of welding slag to the greatest extent and avoiding pollution and short circuits caused by welding slag.

[0059] Since the second protective film 14 is pre-bonded to the top surface of the end of the avoidance hole 120 away from the first protective film 13, when the bare battery cell 4 lies flat on the film body 11, the battery adapter tab 3 is just located at the avoidance hole 120, and the top cover 2 is located at the bottom film of the connecting film 12. At this time, welding of the battery adapter tab 3 and the pole column 21 needs to be carried out through above the avoidance hole 120. And because one end of the second protective film 14 is bonded to the top surface of the edge of the avoidance hole 120, and the second protective film 14 has a certain flexibility and will collapse downward, thus blocking the avoidance hole 120 and affecting the welding of the battery adapter tab 3 and the pole column 21.

[0060] Therefore, referring to the attached Figure 5 and 6 As shown, in this embodiment, stop posts 22 are symmetrically arranged on one side of the two ends of the top cover 2 in the length direction facing the connecting film 12, and the distance between the two stop posts 22 is greater than or equal to the length of the connecting film 12. A stop hole 141 connected to the stop post 22 is opened at one end of the second protective film 14 away from the avoidance hole 120.

[0061] With this setting, by folding the second protective film 14 outward along the length direction of the avoidance hole 120 and sleeving the stop hole 141 at the end of the second protective film 14 on the stop post 22, position constraint of the second protective film 14 outside the avoidance hole 120 can be achieved, avoiding the second protective film 14 from blocking the avoidance hole 120 and facilitating welding of the top surface of the battery adapter tab 3 and the pole column 21.

[0062] In order to conveniently and quickly sleeve the stop hole 141 on the stop post 22, in this embodiment, the stop hole 141 and the stop post 22 are in clearance fit. However, during the laser welding process of the battery adapter tab 3 and the pole column 21, there is a certain mechanical vibration, which will cause the second protective film 14 to break away from the stop post 22, thus affecting the welding operation between the battery adapter tab 3 and the pole column 21. It is necessary to manually sleeve the second protective film 14 on the stop post 22 through the stop hole 141 again, which will affect the welding efficiency.

[0063] To this end, in this embodiment, a plurality of stop grooves 221 are provided on one side of the stop post 22 in the length direction toward the top cover 2, and the plurality of stop grooves 221 are arranged at intervals along the axial direction of the stop post 22. The second protective film 14 can be clamped in the stop grooves 221 through the stop holes 141, so as to prevent the stop holes 141 from detaching from the stop post 22 during the welding vibration of the battery adapter piece 3 and the pole column 21, affecting the normal progress of welding.

[0064] The present invention also discloses an assembly method for a cell packaging structure, including the following steps:

[0065] S1. Ultrasonically weld the pole ears 41 of the bare cell 4 to the battery adapter piece 3; Place two bare cells 4 flat, with the pole ears 41 facing each other. The positive pole ears on the two bare cells 4 are welded through one battery adapter piece 3, and the negative pole ears on the two bare cells 4 are welded through one battery adapter piece 3, and both the positive and negative pole ears are welded on the front surface of the battery adapter piece 3.

[0066] S2. Lay the insulating film 1 flat, place the bare cell 4 flat on the film body 11, and place the battery adapter piece 3 in the avoidance hole 120 of the connecting film 12. In this embodiment, the area of the avoidance hole 120 is larger than the area of the battery adapter piece 3, facilitating the battery adapter piece 3 to pass through the avoidance hole 120.

[0067] S3. Paste the first protective film 13 on the surface of the battery adapter piece 3 away from the welding area of the pole ear 41.

[0068] S4. Place the top cover 2 on the side of the connecting film 12 away from the bare cell 4, and laser weld the pole column 21 on the top cover 2 and the battery adapter piece 3;

[0069] S5. Paste the second protective film 14 on the surface of the pole ear 41 and the side of the battery adapter piece 3 away from the pole column 21; Before performing step S5, first sleeved the second protective film 14 on the stop post 22 at the end of the top cover 2 through the stop hole 141 at its end, so that the second protective film 14 avoids the avoidance hole 120, facilitating the welding of the battery adapter piece 3 and the pole column 21.

[0070] S6. Wrap the film body 11 around the outer surface of the bare cell 4. After the film body 11 is wrapped around the outer surface of the bare cell 4, the joint of the film body 11 is welded by a thermal melting method. In this embodiment, the method of wrapping the film body 11 around the bare cell belongs to the prior art.

[0071] The present invention also discloses a secondary battery, including a housing and the cell packaging structure described above. Two bare cells 4 are arranged side by side in the housing, and the cover plate is hermetically connected to the open end of the housing.

[0072] Through the cell film wrapping structure disclosed in this embodiment, before the battery connection tab 3 is welded to the pole column 21, the first protective film 13 can protect the surface of the battery connection tab 3 away from the welding area of the tab 41. After the battery connection tab 3 is welded to the pole column 21, the second protective film 14 can protect the tab 41 and the side of the battery connection tab 3 away from the pole column 21. The first protective film 13 and the second protective film 14 can completely wrap the tab 41 and the battery connection tab 3, minimizing the generation of welding slag to the greatest extent and avoiding the pollution and short circuit caused by the welding slag. At the same time, the insulating film 1 of this embodiment can be used to wrap the bare cell 4 and can also be used to stick the tab 41 of the bare cell 4, reducing the sticking step, optimizing the film wrapping form, and providing comprehensive protection for the bare cell 4 and the tab 41 area.

[0073] By adopting the above-mentioned insulating film 1 and the cell film wrapping structure, the secondary battery of this embodiment can avoid the short circuit caused by the welding slag generated during the production of the secondary battery to the inside of the bare cell 4, improving the safety and reliability of the secondary battery.

[0074] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An insulating film, which comprises two film bodies (11) and a connecting film (12) connected between the two film bodies (11), and the film bodies (11) are used for wrapping a bare battery cell (4); It is characterized in that: Both ends in the length direction of the connecting film (12) are respectively provided with avoidance holes (120), and the avoidance holes (120) are used for allowing a battery connecting piece (3) to pass through; One end of the avoidance hole (120) facing the middle of the connecting film (12) is provided with a first protective film (13), and the first protective film (13) is used for sticking to one side of the battery connecting piece (3) away from the tab (41) of the bare battery cell (4); The top surface of one end of the avoidance hole (120) away from the first protective film (13) is provided with a second protective film (14), and the second protective film (14) is used for sticking to the surface of the tab (41) of the bare battery cell (4) and one side of the battery connecting piece (3) away from the terminal post (21); 2. The insulating film according to claim 1, wherein: The area of the first protective film (13) is greater than or equal to the area of the welding region of the tab (41) on the battery connecting piece (3); 3. The insulating film according to claim 2, wherein: The front surface of the first protective film (13) is provided with a first double-sided adhesive tape, and the first double-sided adhesive tape is used for sticking to one side of the battery connecting piece (3) away from the tab (41); 4. The insulating film according to claim 1, characterized in that: The area of the second protective film (14) is greater than or equal to the total area of the welding of the tab (41) and the terminal post (21) on the battery connecting piece (3); 5. The insulating film according to claim 4, wherein: The back surface of the second protective film (14) is provided with a second double-sided adhesive tape, and the second double-sided adhesive tape is used for bonding with the surface of the tab (41) and one side of the battery connecting piece (3) away from the terminal post (21); 6. A battery cell packaging structure, which comprises a top cover (2), a battery connecting piece (3), a bare battery cell (4) and the insulating film according to any one of claims 1 to 5, and is characterized in that: Two bare battery cells (4) are provided, and are respectively laid flat on the film body (11), the tabs (41) of the two bare battery cells (4) are arranged oppositely, the tabs (41) on the bare battery cells (4) are welded to the front surface of the battery connecting piece (3), and the battery connecting piece (3) is located at the avoidance hole (120); The first protective film (13) is stuck to one side of the battery connecting piece (3) away from the tab (41), and the top cover (2) is arranged on the bottom surface of the connecting film (12); The terminal post (21) on the top cover (2) is welded to the surface of one end of the battery connecting piece (3) away from the first protective film (13); The second protective film (14) is stuck to the surface of the tab (41) and one side of the battery connecting piece (3) away from the terminal post (21), and the film body (11) wraps the outer surface of the bare battery cell (4); 7. The cell coating structure according to claim 6, wherein: Both ends in the length direction of the top cover (2) are symmetrically provided with stop posts (22) on one side facing the connecting film (12), the distance between the two stop posts (22) is greater than or equal to the length of the connecting film (12), and a stop hole (141) connected to the stop post (22) is opened at one end of the second protective film (14) away from the avoidance hole (120).

8. The cell coating structure according to claim 7, characterized in that: A plurality of stopping grooves (221) are arranged on one side of the stopping column (22) in the length direction of the top cover (2). The plurality of stopping grooves (221) are arranged at intervals along the axial direction of the stopping column (22). The stopping hole (141) is used for being clamped on the stopping groove (221).

9. An assembly method of the cell coating structure as described in claim 6, characterized in that: It includes the following steps: S1. Ultrasonically weld the tab (41) of the bare battery cell (4) to the battery adapter plate (3). S2. Lay the insulating film flat, place the bare battery cell (4) flat on the film body (11), and place the battery adapter plate (3) in the avoidance hole (120) of the connecting film (12). S3. Paste the first protective film (13) on the side of the battery adapter plate (3) away from the tab (41). S4. Place the top cover (2) on the side of the connecting film (12) away from the bare battery cell (4), and laser-weld the pole column (21) on the top cover (2) and the battery adapter plate (3). S5. Paste the second protective film (14) on the surface of the tab (41) and the side of the battery adapter plate (3) away from the pole column (21). S6. Wrap the film body (11) around the outer surface of the bare battery cell (4).

10. A secondary battery, comprising a housing and the cell coating structure as described in claim 6, characterized in that: Two bare battery cells (4) are arranged side by side in the shell, and the cover plate is hermetically connected to the open end of the shell.

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