Insulating film, battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and provides an insulating film, a battery cell and a battery pack, the insulating film comprises a first film group and a second film group; the first film group comprises a first film body, a second film body and a third film body which are connected in sequence, and the second film body is provided with an avoiding hole through which a tab penetrates and a containing table protruding towards one side; the first film body or the third film body is provided with a bottom supporting plate, and the bottom supporting plate is provided with an exhaust structure. The two sides of the first membrane set are each connected with a second membrane set, and each second membrane set comprises a first turnover body, a second turnover body and a third turnover body. Wherein the first film body and the third film body can be folded relative to the second film bodies and connected, the first folding body, the second folding body and the third folding body of each second film group can be folded relative to the first film group and connected, so that the first film group and the two second film groups define a box body structure, and the bottom supporting plate is located on the outer side of the box body structure. According to the invention, the shell entering yield and the exhaust effect of the battery cell are improved, and the safety performance of the battery cell is improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to an insulating film, a battery cell, and a battery pack. Background Technology

[0002] The battery pack includes a housing and battery modules assembled inside the housing. Each battery module consists of multiple cells, and the terminals of the multiple cells are electrically connected through busbars. The housing provides physical support and protection for the battery modules. Each battery cell includes a housing, a top cover assembly, and terminal groups, which are disposed within a cavity formed by the housing and top cover assembly.

[0003] The top cover assembly includes a top cover body, pole posts, and an insulating component. The pole posts are disposed on the top cover body, and the top cover body is welded and sealed to the housing. The insulating component is located between the cover body and the pole group and defines a space for accommodating the pole group's tabs.

[0004] In traditional battery cell structures, an insulating film is wrapped around the outside of the electrode assembly to achieve insulation between the electrode assembly and the casing. The insulating film and the insulating component are fixed together by heat fusion. However, in some battery cell structures, the insulating component is relatively thin, which affects the low bonding yield between it and the insulating film, thus impacting the performance of the battery cell. Summary of the Invention

[0005] This invention provides an insulating film, a battery cell, and a battery pack to solve the problem of low yield of insulating film fixation in the battery cell structure in the prior art.

[0006] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, the present invention provides an insulating film for use in a battery cell, comprising: The first membrane assembly includes a first membrane body, a second membrane body, and a third membrane body connected sequentially along a first direction. The second membrane body is provided with a clearance hole for the electrode tab to pass through. On the side of the clearance hole, the second membrane body forms a receiving platform that protrudes to one side, and the receiving platform is used to receive a support platform for the electrode assembly. The end of the first membrane body or the third membrane body opposite to the second membrane body is provided with a bottom support plate in a direction perpendicular to the first direction, and the bottom support plate has a venting structure. The second membrane group is connected to the first membrane group on both sides of the second direction. The second membrane group includes a first folding body, a second folding body and a third folding body distributed along the first direction. The first folding body is connected to the first membrane body, the second folding body is connected to the second membrane body, and the third folding body is connected to the third membrane body. The first membrane and the third membrane can be folded and connected relative to the second membrane, and the first folding body, the second folding body and the third folding body of each second membrane group can be folded and connected relative to the first membrane group, so that the first membrane group and the two second membrane groups form a box structure, and the bottom support plate is located on the outside of the box structure.

[0007] According to an insulating film provided by the present invention, the first film body includes a first wrapping portion and a second wrapping portion, the first wrapping portion being connected to the second film body; the third film body includes a third wrapping portion and a fourth wrapping portion, the third wrapping portion being connected to the second film body. The second wrapping portion is foldable relative to the first wrapping portion, and the fourth wrapping portion is foldable relative to the third wrapping portion, such that the second wrapping portion and the fourth wrapping portion at least partially overlap and are opposite to the second film body, and the bottom support plate is located outside the second wrapping portion or the fourth wrapping portion.

[0008] According to an insulating film provided by the present invention, the exhaust structure is provided in multiple ways, and the multiple exhaust structures are arranged in parallel and spaced apart along the first direction.

[0009] According to an insulating film provided by the present invention, the venting structure is an arc-shaped groove, which extends along the length direction of the battery cell.

[0010] According to an insulating film provided by the present invention, the thickness of the end of the first film body or the third film body away from the second film body is t5, the height of the bottom support plate is t6, and the distance between the bottom of the arc-shaped groove and the end of the first film body or the third film body away from the second film body is t7, satisfying: 0.08mm≤t5≤0.15mm, 0.8mm≤t6≤1.5mm, 0.3≤t7 / t6≤0.6; And / or, along the first direction, the distance between the groove opening end of the arc-shaped groove and the edge of the bottom support plate is W3, and the distance between the groove opening ends of adjacent arc-shaped grooves is W4, satisfying: W3≥2mm, W4≥2mm.

[0011] According to an insulating film provided by the present invention, the first film body or the third film body has a fourth adhesive layer at one end opposite to the second film body, and the bottom support plate is bonded and fixed to the first film body or the third film body opposite to the second film body through the fourth adhesive layer. The thickness of the fourth adhesive layer is t3, which satisfies: 0.1mm≤t3≤0.15mm.

[0012] According to an insulating film provided by the present invention, along the width direction of the battery cell, the width of the fourth adhesive layer is W1, and the width of the bottom support plate is W2, satisfying the following: 2.5mm≤(W2-W1) / 2≤5mm, 0.2≤(2W3+W4) / W2≤0.35.

[0013] In a second aspect, the present invention provides a battery cell comprising: a top cover assembly, an electrode group, a housing, and an insulating film as described above; The housing has an opening, the top cover assembly is disposed in the opening and surrounds the housing to form a receiving cavity, the electrode group is disposed in the receiving cavity, and the insulating film is located between the electrode group and the housing; The electrode assembly has a first end face and a second end face facing away from each other, and two first side faces and two second side faces connected between the first end face and the second end face. The two first side faces are arranged facing away from each other, and the two second side faces are arranged facing away from each other. An electrode tab is connected to the first end face, and the electrode tab passes through the clearance hole. A support platform is formed on the side of the electrode tab on the first end face. The support platform is arranged opposite to the receiving platform. The second membrane body is wrapped around the first end face. The first membrane body and the third membrane body are respectively wrapped around the two first side faces and the second end face. The two second membrane assemblies are folded relative to the first membrane assembly and are wrapped around the two second side faces one by one.

[0014] According to a battery cell provided by the present invention, along the height direction of the battery cell, the height of the support platform of the electrode group is H1, and the height of the receiving platform is H2; along the length direction of the battery cell, the length of the support platform is L1, and the length of the receiving platform is L2; ​​satisfying: 0.5mm≤(L2-L1) / 2≤1mm, 0.2mm≤(H2-H1) / 2≤0.5mm.

[0015] Thirdly, the present invention provides a battery pack, comprising: a busbar, a housing, and battery cells as described above; The housing forms a receiving cavity, and multiple battery cells are provided, with the multiple battery cells stacked in the receiving cavity; the busbar is connected to the terminals of the multiple battery cells.

[0016] The insulating film, battery cell, and battery pack provided by this invention, by setting a first film group and two second film groups, with a second film group connected to each side of the first film group in the second direction, can use the first film group to wrap two end faces and two opposite sides of the electrode group, and use the three folding bodies of the second film group to fold relative to the first film group to wrap the other two opposite sides of the electrode group, to achieve complete wrapping of the six faces of the cubic electrode group. There is no need to heat-melt the insulating film to the insulating component on the top cover body, thus eliminating the adverse effects on the performance of the battery cell caused by the low yield of heat-melting the insulating film and the insulating component. Furthermore, since the insulating film completely covers the outer surface of the electrode assembly, it can prevent short circuits between the electrode assembly and the casing, improve the insulation of the insulating film inside the cell, and reduce the risk of short circuits between the electrode assembly and the casing. In addition, the second membrane has a receiving platform protruding to one side to receive the support platform of the electrode assembly. By limiting the support platform through the receiving platform, the fixing effect of the electrode assembly in the cell is improved, preventing the electrode assembly from moving around, improving the insulation effect inside the cell, and increasing the cell capacity. Moreover, a bottom support plate is provided at the end of the first membrane or the third membrane away from the second membrane along the vertical direction of the first direction, and the bottom support plate has a venting structure. When the insulating film surrounds and forms a box structure, the bottom support plate is located on the outside of the box structure, which improves the cell's casing yield and venting effect, and improves the cell's safety performance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is an unfolded diagram of the insulating film provided by the present invention.

[0019] Figure 2 This is one of the schematic diagrams of the three-dimensional structure of the insulating film after folding provided by the present invention.

[0020] Figure 3 This is the second schematic diagram of the three-dimensional structure of the insulating film after folding provided by the present invention.

[0021] Figure 4 This is a top view of the insulating film provided by the present invention after folding.

[0022] Figure 5 This is one of the partial front views of the insulating film after folding provided by the present invention.

[0023] Figure 6 This is the second partial front view of the insulating film after folding provided by the present invention.

[0024] Figure 7 This is a front view of the insulating film folded without the bottom support plate provided by the present invention.

[0025] Figure 8 This is a front view of the pole group provided by the present invention.

[0026] Figure 9 This is a top view of the pole group provided by the present invention.

[0027] Figure 10 This is one of the three-dimensional structural diagrams of the insulating film and electrode assembly provided by the present invention.

[0028] Figure 11 This is the second schematic diagram of the three-dimensional structure of the insulating film and electrode assembly provided by the present invention.

[0029] Figure 12 This is one of the three-dimensional structural schematic diagrams of the top cover assembly provided by the present invention.

[0030] Figure 13 This is a front view of the top cover assembly provided by the present invention.

[0031] Figure 14 This is a three-dimensional structural diagram of the top cover body provided by the present invention.

[0032] Figure 15 This is the second three-dimensional structural schematic diagram of the top cover assembly provided by the present invention.

[0033] Figure 16 This is a bottom view of the first type of top cover assembly provided by the present invention.

[0034] Figure 17 This is a schematic diagram of the folding plate of the first type of top cover assembly provided by the present invention in the open state.

[0035] Figure 18 This is a bottom view of the second type of top cover assembly provided by the present invention.

[0036] Figure 19 This is a schematic diagram of the folding plate of the second type of top cover assembly provided by the present invention in the open state.

[0037] Figure 20 This is a three-dimensional structural diagram of the battery cell provided by the present invention.

[0038] Figure label: 1. Insulating film; 11. First membrane assembly; 12. Second membrane assembly; 13. First adhesive layer; 14. Second adhesive layer; 15. Third adhesive layer; 16. Base plate; 17. Fourth adhesive layer; 18. Crease; 111. First membrane body; 112. Second membrane body; 113. Third membrane body; 121. First fold body; 122. Second fold body; 123. Third fold body; 161. Venting structure; 1111. First wrapping part; 1112. Second wrapping part; 1121. Clearance hole; 1122. Receiving platform; 1131. Third wrapping part; 1132. Fourth wrapping part; 2. Top cover assembly; 21. Top cover body; 22. Pole post; 23. Explosion-proof valve; 24. Insulating component; 25. Connecting piece; 211. First protrusion; 212. Second protrusion; 213. Rib; 214. Vent hole; 241. Slot; 242. Fixing plate; 243. Folding plate; 251. Base part; 252. Extension part; 2131. First rib; 2132. Second rib; 2421. Fitting part; 2422. Supporting part; 2423. First venting structure; 2431. First plate; 2432. Second plate; 2433. Third plate; 2434. Second venting structure; 24211. First fitting plate; 24212. Second fitting plate; 24213. Third fitting plate; 24221. Groove; 3. Pole assembly; 31. First side surface; 32. Second side surface; 33. First end face; 34. Second end face; 35. Pole tab; 331. Support platform; 3311. Exhaust groove; 4. Casing; 100. Battery cell. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] The following is combined Figures 1 to 20 The insulating film, battery cell, and battery pack provided in the embodiments of the present invention will be described in detail through specific embodiments and application scenarios.

[0041] Firstly, such as Figure 1 and Figure 2 As shown, this embodiment provides an insulating film 1, which is applied to a battery cell 100, including: a first film assembly 11 and a second film assembly 12.

[0042] The first membrane assembly 11 includes a first membrane body 111, a second membrane body 112, and a third membrane body 113 connected sequentially along a first direction. The second membrane body 112 is provided with a clearance hole 1121 through which the electrode tab 35 passes. On the side of the clearance hole 1121, the second membrane body 112 forms a receiving platform 1122 protruding to one side, which is used to receive the support platform 331 of the electrode assembly 3. The end of the first membrane body 111 or the third membrane body 113 opposite to the second membrane body 112 is provided with a bottom support plate 16 in the direction perpendicular to the first direction. The bottom support plate 16 has an exhaust structure 161.

[0043] The first membrane group 11 is connected to a second membrane group 12 on each side of the second direction. The second membrane group 12 includes a first folding body 121, a second folding body 122 and a third folding body 123 distributed along the first direction. The first folding body 121 is connected to the first membrane group 111, the second folding body 122 is connected to the second membrane group 112, and the third folding body 123 is connected to the third membrane group 113.

[0044] The first membrane 111 and the third membrane 113 can be folded and connected relative to the second membrane 112 respectively. The first folding body 121, the second folding body 122 and the third folding body 123 of each second membrane group 12 can be folded and connected relative to the first membrane group 11, so that the first membrane group 11 and the two second membrane groups 12 form a box structure, and the bottom support plate 16 is located on the outside of the box structure.

[0045] Understandably, in this embodiment, the insulating film 1 is applied to the cubic structure of the battery cell 100 to wrap around the outside of the cubic electrode assembly 3. During the assembly of the battery cell 100, the insulating film 1 is supplied as a pre-cut sheet insulating film.

[0046] Two second membrane units 12 are respectively connected to the two sides of the first membrane unit 11. A first folding body 121 is connected to each side of the first membrane 111, a second folding body 122 is connected to each side of the second membrane 112, and a third folding body 123 is connected to each side of the third membrane 113.

[0047] like Figure 8 and Figure 9 As shown, the electrode assembly 3 has a first end face 33 and a second end face 34 facing away from each other. An electrode tab 35 is connected to the first end face 33, and two first side faces 31 and two second side faces 32 are connected between the first end face 33 and the second end face 34. The two first side faces 31 are arranged facing away from each other, and the two second side faces 32 are arranged facing away from each other.

[0048] Furthermore, a receiving platform 1122 is formed beside the clearance hole 1121. The receiving space of the receiving platform 1122 faces the electrode group 3, and the receiving space is used to receive the support platform 331 of the electrode group 3. The length of the support platform 331 is less than the length of the receiving platform 1122. Since the support platform 331 is assembled into the receiving platform 1122, the receiving platform 1122 can limit the displacement of the electrode group 3 within the insulating film 1. The peripheral wall of the receiving platform 1122 stops the electrode group 3 from the length and width directions of the cell 100, thus fixing the electrode group 3. When the cell 100 is subjected to impact force, it prevents the electrode group 3 from moving along the length and width directions of the cell 100, which would lead to poor insulation of the electrode group 3. Since both the insulating film 1 and the electrode group 3 protrude towards the top cover assembly 2, the capacity of the cell 100 is increased.

[0049] When the insulating film 1 is wrapped around the electrode assembly 3, the second film 112 can be wrapped around the first end face 33, and the electrode tab 35 can be passed through the clearance hole 1121, so that the support platform 331 of the electrode assembly 3 extends into the receiving platform 1122. The first film 111 and the third film 113 are both folded relative to the second film 112, so that the first film 111 wraps around at least a part of a first side face 31 and a second end face 34, and the other second film 112 wraps around at least a part of another first side face 31 and a second end face 34. Then, the first folding body 121 of one of the second membrane groups 12 is folded relative to the first membrane body 111, the second folding body 122 is folded relative to the second membrane body 112, and the third folding body 123 is folded relative to the third membrane body 113. The first folding body 121, the second folding body 122, and the third folding body 123 are stacked on a second side surface 32. Similarly, the first folding body 121, the second folding body 122, and the third folding body 123 of the other second membrane group 12 are stacked on another second side surface 32.

[0050] The insulating film 1 wraps around the six sides of the electrode assembly 3, namely the first end face 33, the second end face 34, the two first side faces 31, and the two second side faces 32, forming a cubic box structure. The first membrane body 111 and the third membrane body 113 can be fixedly connected by adhesive, as can the first folded body 121, the second folded body 122, and the third folded body 123.

[0051] In traditional technology, only the four sides of the insulating film 1 and the electrode group 3 are covered. The insulating film 1 needs to be thermally fused to the insulating component on the top cover assembly 2. If the thickness of the insulating component is too thin, it will reduce the yield of the thermal fusion fixation between the insulating film 1 and the insulating component, and affect the performance of the cell 100.

[0052] Furthermore, in this embodiment, a bottom support plate 16 is integrated on the insulating film 1. The bottom support plate 16 is located on the insulating film 1 corresponding to the second end face 34 of the electrode assembly 3, and supports the insulating film 1 at the bottom of the electrode assembly 3. Since the bottom support plate 16 is located on the outside of the box structure formed by the insulating film 1 wrapping the electrode assembly 3, after the electrode assembly 3 is installed into the housing 4, the bottom support plate 16 is located between the bottom of the electrode assembly 3 and the housing 4, so that a certain gap is maintained between the housing 4 and the bottom of the electrode assembly 3. Since the bottom support plate 16 is inserted into the housing 4 along with the insulating film 1 when the electrode assembly 3 and the insulating film 1 are installed, the bottom of the insulating film 1 is always kept flat due to the supporting effect of the bottom support plate 16, which can prevent the insulating film 1 wrapped at the bottom of the electrode assembly 3 from being damaged by the housing 4. Furthermore, the bottom plate 16 has an exhaust structure 161, which can provide an exhaust channel between the housing 4 and the electrode group 3. When the cell 100 experiences high-temperature thermal runaway, the high-temperature gas can converge towards the explosion-proof valve through the exhaust structure 161, reducing the risk of housing 4 rupture and fire explosion caused by poor exhaust, and improving the safety performance of the cell 100.

[0053] Since the bottom support plate 16 located on the bottom surface of the electrode group 3 extends along the length direction of the cell 100, it provides maximum support for the first membrane 111 or the third membrane 113, thereby enhancing the support effect.

[0054] Specifically, the venting structure 161 also extends along the length of the cell 100. The venting structure 161 can be arranged along a straight line, an arc, or a broken line. The venting structure 161 can be a recessed part or an additional venting pipe. There can be only one venting structure 161 or multiple venting structures 161.

[0055] Specifically, the base plate 16 can be fixed to the first membrane 111 or the third membrane 113 either by adhesive or by ultrasonic welding. There is no specific limitation on either method; the only requirement is that the base plate 16 is located outside the housing structure after the insulating film 1 wraps around the electrode group 3. Since the insulating film 1 and the base plate 16 are assembled before leaving the factory, during the assembly of the battery cell 100, the insulating film 1 with the base plate 16 is directly wrapped around the electrode group 3 before being installed into the housing 4, thus improving the assembly efficiency of the battery cell 100.

[0056] The insulating film 1 provided by this invention is applied to the battery cell 100. By setting a first film group 11 and two second film groups 12, the first film group 11 is connected to a second film group 12 on each side in the second direction. The first film group 11 can wrap the two end faces and two opposite sides of the electrode group 3. The three folding bodies of the second film group 12 are folded relative to the first film group 11 to wrap the other two opposite sides of the electrode group 3, so as to achieve complete wrapping of the six faces of the cubic electrode group 3. There is no need to heat-melt the insulating film 1 to the insulating component on the top cover body, thus eliminating the adverse effects on the performance of the battery cell 100 caused by the low heat-melting yield of the insulating film 1 to the insulating component. Furthermore, since the insulating film 1 completely covers the outer surface of the electrode group 3, it can prevent the electrode group 3 from short-circuiting with the housing 4, improve the insulation of the insulating film 1 inside the cell 100, and reduce the risk of short circuit between the electrode group 3 and the housing 4. In addition, the second film 112 has a receiving platform 1122 protruding to one side for receiving the support platform 331 of the electrode group 3. By limiting the support platform 331 by the receiving platform 1122, the fixing effect of the electrode group 3 inside the cell 100 is improved, preventing the electrode group 3 from moving, improving the insulation effect inside the cell 100, and increasing the capacity of the cell 100. In addition, a bottom support plate 16 is provided at the end of the first film 111 or the third film 113 away from the second film 112 along the vertical direction of the first direction, and the bottom support plate 16 has an exhaust structure 161. When the insulating film 1 is enclosed to form a box structure, the bottom support plate 16 is located outside the box structure, which improves the casing yield and exhaust effect of the cell 100 and improves the safety performance of the cell 100.

[0057] like Figure 2 and Figure 3 As shown, the first membrane 111 in this embodiment includes a first wrapping portion 1111 and a second wrapping portion 1112, with the first wrapping portion 1111 connected to the second membrane 112; the third membrane 113 includes a third wrapping portion 1131 and a fourth wrapping portion 1132, with the third wrapping portion 1131 connected to the second membrane 112.

[0058] The second wrapping portion 1112 can be folded relative to the first wrapping portion 1111, and the fourth wrapping portion 1132 can be folded relative to the third wrapping portion 1131, so that the second wrapping portion 1112 and the fourth wrapping portion 1132 at least partially overlap and are opposite to the second film 112, and the bottom support plate 16 is located outside the second wrapping portion 1112 or the fourth wrapping portion 1132.

[0059] Understandably, the first wrapping portion 1111 and the third wrapping portion 1131 respectively cover the two first side surfaces 31 of the pole assembly 3. The second wrapping portion 1112 is folded over relative to the first wrapping portion 1111 and covers at least a portion of the second end face 34. The fourth wrapping portion 1132 is folded over relative to the third wrapping portion 1131 and covers at least a portion of the second end face 34. The second wrapping portion 1112 and the fourth wrapping portion 1132 overlap and cover the second end face 34, and the two can be fixedly connected by adhesive.

[0060] Optionally, a crease 18 is provided at the connection between the first wrapping part 1111 and the second wrapping part 1112, and a crease 18 is provided at the connection between the third wrapping part 1131 and the fourth wrapping part 1132. The crease 18 can be formed by mechanical creasing or hot creasing.

[0061] Since the bottom plate 16 is located outside the second wrapping portion 1112 or the fourth wrapping portion 1132, when the insulating film 1 wraps the electrode group 3 to form a box structure, the bottom plate 16 has an exhaust structure 161 outside the second wrapping portion 1112 or the fourth wrapping portion 1132 for exhausting the battery cell 100 when thermal runaway occurs.

[0062] like Figure 2 As shown, the exhaust structure 161 of this embodiment is provided in multiple ways, and the multiple exhaust structures 161 are arranged in parallel at intervals along the first direction.

[0063] Understandably, in order to improve the exhaust effect of the base plate 16, multiple exhaust structures 161 are provided on the base plate 16 in this embodiment. The multiple exhaust structures 161 are arranged in parallel at intervals, and the multiple exhaust structures 161 form an exhaust channel covering the second end face 34 of the electrode group 3, thereby enhancing the exhaust effect.

[0064] like Figure 5 and Figure 6 As shown, the exhaust structure 161 in this embodiment is an arc-shaped groove, which extends along the length of the battery cell 100.

[0065] Understandably, the smooth flow lines within the arc-shaped groove can significantly reduce gas flow resistance and evenly distribute stress, avoiding stress concentration at sharp corners, thereby extending the service life of the exhaust structure 161.

[0066] like Figure 5 As shown, in this embodiment, the thickness of the end of the first membrane 111 or the third membrane 113 away from the second membrane 112 is t5, the height of the bottom support plate 16 is t6, and the distance between the bottom of the arc-shaped groove and the end of the first membrane 111 or the third membrane 113 away from the second membrane 112 is t7, satisfying: 0.08mm≤t5≤0.15mm, 0.8mm≤t6≤1.5mm, 0.3≤t7 / t6≤0.6.

[0067] Understandably, in order to ensure the insulation quality of the end of the first membrane 111 or the third membrane 113 facing away from the second membrane 112 to the bottom of the electrode assembly 3, the thickness of the end of the first membrane 111 or the third membrane 113 facing away from the second membrane 112 in this embodiment needs to meet a certain range. Furthermore, in order to ensure the supporting strength of the bottom support plate 16 to the insulating film 1 at the bottom of the electrode assembly 3, the height of the bottom support plate 16 also needs to meet a certain range. Since the height of the bottom support plate 16 is pressed between the insulating film 1 and the housing 4, and the distance between the bottom of the arc-shaped groove in the venting structure 161 and the side of the bottom support plate 16 near the insulating film 1 is also a solid structure, in order to ensure that the bottom support plate 16 meets the supporting strength while venting, the ratio of the distance between the bottom of the arc-shaped groove and the end of the first membrane 111 or the third membrane 113 facing away from the second membrane 112 to the height of the bottom support plate 16 needs to meet a certain range.

[0068] Specifically, t5 can be 0.08mm, 0.115mm, or 0.15mm. t6 can be 0.8mm, 1.15mm, or 1.5mm. t7 / t6 can be 0.3mm, 0.45mm, or 0.6mm.

[0069] like Figure 6 As shown, along the first direction, the distance between the groove end of the arc-shaped groove and the edge of the bottom support plate 16 in this embodiment is W3, and the distance between the groove ends of adjacent arc-shaped grooves is W4, satisfying: W3≥2mm, W4≥2mm.

[0070] Understandably, taking two parallel arc-shaped grooves on a base plate 16 as an example, in order to ensure the strength of the support of the base plate 16 without arc-shaped grooves to the insulating film 1 at the bottom of the housing 4 and the pole group 3, the distance between the groove opening end of the arc-shaped groove and the edge of the base plate 16, as well as the distance between the groove opening ends of adjacent arc-shaped grooves, must meet certain ranges.

[0071] Specifically, W3 can be 2mm, 2.5mm, or 3mm. W4 can be 2mm, 2.5mm, or 3mm.

[0072] like Figure 5 As shown, in this embodiment, the first membrane 111 or the third membrane 113 has a fourth adhesive layer 17 at the end opposite to the second membrane 112. The bottom plate 16 is bonded and fixed to the end of the first membrane 111 or the third membrane 113 opposite to the second membrane 112 through the fourth adhesive layer 17. The thickness of the fourth adhesive layer 17 is t3, which satisfies: 0.1mm≤t3≤0.15mm.

[0073] Understandably, in this embodiment, a fourth adhesive layer 17 is provided at the position where the base plate 16 is fixed on the insulating film 1. When the base plate 16 is fixed to the insulating film 1, the base plate 16 and the insulating film 1 are adhered and fixed by the fourth adhesive layer 17. In this embodiment, the fourth adhesive layer 17 is provided on the insulating film 1 in advance. When fixing the base plate 16, it is only necessary to peel off the self-adhesive sticker on the surface of the fourth adhesive layer 17 to expose the adhesive surface, and the adhesion between the base plate 16 and the insulating film 1 can be completed. Since there is no need for an additional tape wrapping and pasting step, the assembly process of the base plate 16 and the insulating film 1 is simplified, and the process efficiency is improved.

[0074] Specifically, t3 can be 0.1mm, 0.125mm, or 0.15mm.

[0075] like Figure 6 As shown, in this embodiment, along the width direction of the cell 100, the width of the fourth adhesive layer 17 is W1, and the width of the bottom support plate 16 is W2, satisfying: 2.5mm≤(W2-W1) / 2≤5mm, 0.2≤(2W3+W4) / W2≤0.35.

[0076] Understandably, the difference between the width of the base plate 16 and the width of the fourth adhesive layer 17 needs to meet a certain range. If the fourth adhesive layer 17 is too wide, adhesive overflow will occur; if the fourth adhesive layer 17 is too narrow, the bonding strength of the base plate 16 will be insufficient, and the base plate 16 will easily fall off the insulating film 1. Furthermore, the sum of the distance between the groove ends of the two arc-shaped grooves and the edge of the base plate 16 and the distance between the groove ends of adjacent arc-shaped grooves represents the length of the contact between the base plate 16 and the housing 4. In order to ensure the supporting strength of the base plate 16 to the housing 4 and the smoothness of the venting structure 161, the ratio of the contact length between the base plate 16 and the housing 4 to the width of the base plate 16 needs to meet a certain range.

[0077] Specifically, (W2-W1) / 2 can be 2.5mm, 3.75mm, or 5mm; (2W3+W4) / W2 can be 0.2, 0.275, or 0.35.

[0078] like Figure 3 and Figure 4 As shown, in this embodiment, the first membrane 111 or the third membrane 113 is provided with a first adhesive layer 13 at the end opposite to the second membrane 112, the second folding body 122 is provided with a second adhesive layer 14, and the first folding body 121 or the third folding body 123 is provided with a third adhesive layer 15. The insulating film 1 is bonded and fixed by the first adhesive layer 13, the second adhesive layer 14 and the third adhesive layer 15. The thickness of the first adhesive layer 13, the second adhesive layer 14 and the third adhesive layer 15 is t1, which satisfies: 0.05mm≤t1≤0.1mm.

[0079] Understandably, when the insulating film 1 forms the box structure, it is glued and fixed by the first adhesive layer 13, the second adhesive layer 14, and the third adhesive layer 15. Compared to the prior art where the insulating film 1 is folded to form a box, and then tape is wrapped around the outer surface of the box for fixation, this embodiment pre-sets three adhesive layers on the insulating film 1. When fixing the insulating film 1, it is only necessary to peel off the self-adhesive stickers on the surfaces of the three adhesive layers to expose the adhesive surfaces, thereby completing the gluing of the first film 111 and the third film 113 at the end away from the second film 112, the gluing of the second folded body 122 to the second side 32 of the electrode assembly 3, and the gluing of the first folded body 121 and the third folded body 123. Since no additional tape wrapping and gluing steps are required, the assembly process of the insulating film 1 and the electrode assembly 3 is simplified, and the process efficiency is improved.

[0080] For ease of processing, the first adhesive layer 13, the second adhesive layer 14, and the third adhesive layer 15 in this embodiment have equal thicknesses. Furthermore, this embodiment uses cotton adhesive, which possesses excellent temperature resistance, good insulation properties, flexibility, and adhesion. This facilitates the bonding of the first membrane 111 and the third membrane 113 at the end opposite to the second membrane 112, the bonding of the second folded body 122 to the second side surface 32 of the electrode assembly 3, and the bonding of the first folded body 121 and the third folded body 123.

[0081] Specifically, t1 can be 0.05mm, 0.075mm, or 0.1mm.

[0082] like Figure 3 As shown, in this embodiment, the distance between the first adhesive layer 13, the second adhesive layer 14 and the third adhesive layer 15 and the edge of the insulating film 1 is a, which satisfies: a≥3mm.

[0083] Understandably, to avoid adhesive overflow, the distances between the first adhesive layer 13, the second adhesive layer 14, and the third adhesive layer 15 and the edge of the insulating film 1 cannot be too small. Specifically, the distance between the position of the first adhesive layer 13 at the end of the first film 111 or the third film 113 opposite to the edge of the end of the first film 111 or the third film 113 opposite to the second film 112 is a; the distance between the position of the second adhesive layer 14 on the second folded body 122 and the edge of the second folded body 122 is a; and the distance between the position of the third adhesive layer 15 on the first folded body 121 or the third folded body 123 and the first folded body 121 or the third folded body 123 is a.

[0084] Specifically, 'a' can be 3mm, 3.5mm, or 4mm.

[0085] like Figure 1 and Figure 2As shown, in this embodiment, a crease 18 is provided at the connection between the first membrane 111 and the second membrane 112, and a crease 18 is provided at the connection between the second membrane 112 and the third membrane 113; a crease 18 is provided at the connection between the first folding body 121 and the first membrane 111, a crease 18 is provided at the connection between the second folding body 122 and the second membrane 112, and a crease 18 is provided at the connection between the third folding body 123 and the third membrane 113.

[0086] Understandably, in order to optimize the covering effect of the insulating film 1, this embodiment provides creases 18 at the connection between the first film 111 and the second film 112, the connection between the second film 112 and the third film 113, the connection between the first folding body 121 and the first film 111, the connection between the second folding body 122 and the second film 112, and the connection between the third folding body 123 and the third film 113.

[0087] In this embodiment, the crease 18 is a continuous indentation used to pre-bend the insulating film 1, so that the insulating film 1 is quickly bent along the crease 18 during the process of covering the electrode assembly 3. The insulating film 1 can be permanently creased by means of mechanical indentation or thermal indentation.

[0088] In some embodiments of the present invention, the distance between the creases 18 at both ends of the second membrane 112 in the first direction and the clearance hole 1121 is D1, where D1 ≥ 1 mm. This ensures that the second membrane 112 covers the edge of the second end face 34. If the value of D1 is too small, when the insulating film 1 wraps the electrode group 3, it is easy to cause a short circuit when the portion of the first side 31 or the second side 32 near the first end face 33 comes into contact with the housing 4.

[0089] like Figure 7 As shown, along the height direction of the cell 100, the height of the receiving platform 1122 in this embodiment is H2; the thickness of the second membrane 112 is t2; satisfying: 15≤H2 / t2≤20.

[0090] Understandably, on the second membrane 112, the height of the receiving platform 1122 above the rest of the second membrane 112 is H2, and the thickness of the second membrane 112 is t2. In order to ensure that the receiving platform 1122 cooperates with the support platform 331 to fix the electrode group 3, the ratio of the height of the receiving platform 1122 to the thickness of the second membrane 112 needs to meet a certain range.

[0091] Specifically, H2 / t2 can be 15, 17.5, or 20.

[0092] like Figure 7 As shown, the outer surface area of ​​the receiving platform 1122 in this embodiment is S01, and the projected area of ​​the receiving platform 1122 in the length and width directions of the battery cell 100 is S0, satisfying: 1.8≤S01 / S0≤2.0.

[0093] Understandably, the receiving platform 1122 can be stamped on the insulating film 1. In order to meet the structural strength and process requirements of the stamped receiving platform 1122, the ratio of the outer surface area of ​​the receiving platform 1122 to the projected area of ​​the receiving platform 1122 in the length and width directions of the cell 100 needs to meet a certain range.

[0094] Specifically, S01 / S0 can be 1.8, 1.9, or 2.0.

[0095] like Figure 2 As shown, this embodiment has two clearance holes 1121, which are located on both sides of the receiving platform 1122 along the length of the battery cell 100.

[0096] Understandably, the electrode assembly 3 in this embodiment is provided with two tabs 35, one positive tab and one negative tab. Along the length of the cell 100, the positive tab and the negative tab pass through two clearance holes 1121 on both sides of the receiving platform 1122, respectively. The positive tab is connected to the positive terminal of the top cover assembly 2, and the negative tab is connected to the negative terminal of the top cover assembly 2.

[0097] Furthermore, the receiving platform 1122 is located in the middle of the two clearance holes 1121 and is equidistant from the two clearance holes 1121, making the structure of the second membrane 112 more regular and easier to process and manufacture.

[0098] Secondly, such as Figure 20 As shown, this embodiment provides a battery cell 100, including: a top cover assembly 2, an electrode group 3, a housing 4, and an insulating film 1 as described above.

[0099] The housing 4 has an opening, the top cover assembly 2 is disposed in the opening and surrounds the housing 4 to form a receiving cavity, the electrode group 3 is disposed in the receiving cavity, and the insulating film 1 is located between the electrode group 3 and the housing 4.

[0100] The electrode assembly 3 has a first end face 33 and a second end face 34 facing away from each other, and two first side faces 31 and two second side faces 32 connected between the first end face 33 and the second end face 34. The two first side faces 31 are arranged facing away from each other, and the two second side faces 32 are arranged facing away from each other. The first end face 33 is connected to an electrode tab 35, which passes through a clearance hole 1121. A support platform 331 is formed on the side of the electrode tab 35 on the first end face 33. The support platform 331 is arranged opposite to the receiving platform 1122. The second membrane 112 is wrapped around the first end face 33. The first membrane 111 and the third membrane 113 are respectively wrapped around the two first side faces 31 and the second end face 34. The two second membrane assemblies 12 are folded relative to the first membrane assembly 11 and are wrapped around the two second side faces 32 one by one.

[0101] Specifically, since the battery cell 100 includes an insulating film 1, and the specific structure of the insulating film 1 is as described in the above embodiments, the battery cell 100 shown in this embodiment includes all the technical solutions of the above embodiments. Therefore, it has at least all the beneficial effects obtained by all the technical solutions of the above embodiments, which will not be described in detail here.

[0102] Understandably, the electrode assembly 3 is installed inside the housing 4, and the top cover assembly 2 is placed over the opening of the housing 4. The electrode assembly 3 is electrically connected to the pole of the top cover assembly 2 through the electrode tab 35 to realize the transmission of current. The insulating film 1 is wrapped around the outside of the electrode assembly 3 and is installed inside the housing 4 together with the electrode assembly 3.

[0103] Optionally, the first folded body 121, the second folded body 122, and the third folded body 123 of the same second membrane assembly 12 are bonded and fixed together. The end of the first membrane body 111 away from the second membrane body 112 and the end of the third membrane body 113 away from the second membrane body 112 are bonded and fixed together. For example, they are bonded and fixed together with tape or glue, so that the folded second membrane assembly 12 forms a whole and wraps around the second side surface 32, and the second wrapping part 1112 of the first membrane body 111 and the fourth wrapping part 1132 of the third membrane body 113 wrap around the second end face 34.

[0104] When the first folding body 121, the second folding body 122, and the third folding body 123 are folded to the second side 32, the stacking order of the three is not restricted. For example, the first folding body 121 and the third folding body 123 can be pressed on the outside of the third folding body 123.

[0105] Because the support platform 331 of the electrode assembly 3 in this embodiment extends into the receiving platform 1122 of the second membrane 112, the displacement of the electrode assembly 3 along the length and width directions of the cell 100 is limited, which improves the fixing effect of the electrode assembly 3 within the cell 100, prevents poor insulation caused by the movement of the electrode assembly 3, and increases the capacity of the cell 100. Furthermore, by providing a bottom support plate 16 in the vertical direction of the first direction at the end of the first membrane 111 or the third membrane 113 away from the second membrane 112, and the bottom support plate 16 has a venting structure 161, when the insulating film 1 is enclosed to form a box structure, the bottom support plate 16 is located outside the box structure, which improves the casing yield and venting effect of the cell 100, and improves the safety performance of the cell 100.

[0106] like Figure 8 As shown, along the height direction of the cell 100, the height of the support platform 331 of the electrode group 3 in this embodiment is H1, and the height of the receiving platform 1122 is H2; along the length direction of the cell 100, the length of the support platform 331 is L1, and the length of the receiving platform 1122 is L2; ​​satisfying: 0.5mm≤(L2-L1) / 2≤1mm, 0.2mm≤(H2-H1) / 2≤0.5mm.

[0107] Understandably, in order to facilitate the normal assembly of the support platform 331 of the electrode assembly 3 and the receiving platform 1122 of the insulating film 1, the support platform 331 can be fully inserted into the receiving platform 1122, and the insulating film 1 can fully wrap the electrode assembly 3. The difference between the length of the support platform 331 and the length of the receiving platform 1122, as well as the difference between the height of the support platform 331 and the height of the receiving platform 1122, need to meet certain ranges.

[0108] Specifically, (L2-L1) / 2 can be 0.5mm, 0.75mm, or 1mm. (H2-H1) / 2 can be 0.2mm, 0.35mm, or 0.5mm.

[0109] like Figure 9 As shown, in this embodiment, the support platform 331 of the electrode group 3 is provided with an exhaust groove 3311 on the side facing the top cover assembly 2; the exhaust groove 3311 extends along the length or width direction of the cell 100.

[0110] Understandably, in order to ensure the smooth flow of the explosion-proof valve exhaust channel, the support platform 331 of the electrode group 3 in this embodiment is provided with an exhaust groove 3311. There are multiple exhaust grooves 3311, some of which extend along the length direction of the battery cell 100, and the remaining parts of which extend along the width direction of the battery cell 100. The exhaust grooves 3311 along the length direction and the exhaust grooves 3311 along the width direction intersect.

[0111] The exhaust groove 3311 is connected to the exhaust channel of the explosion-proof valve, allowing sufficient space for the high-temperature gas to flow until it reaches the explosion-proof valve. Furthermore, since the exhaust groove 3311 is arranged along the length and width of the cell 100, the high-temperature gas from other parts of the electrode group 3 can also enter the exhaust groove 3311 from the side of the support platform 331, which is beneficial to the flow of high-temperature gas.

[0112] like Figure 12 , Figure 13 and Figure 14 As shown, the top cover assembly 2 provided in this embodiment of the invention includes a top cover body 21, a terminal post 22, and an explosion-proof valve 23. The top cover body 21 is bent to form a boss, which includes a plurality of protrusions stacked along the height direction of the top cover body 21. The topmost protrusion has a vent hole 214 penetrating the top cover body 21, and at least one of the other protrusions is adapted to be connected to the battery pack housing support. The terminal post 22 is inserted into the top cover body 21 along the height direction and is spaced apart from the boss along the length direction of the top cover body 21. The explosion-proof valve 23 is installed on the topmost protrusion and is opposite to the vent hole 214.

[0113] See the length, width, and height directions of the top cover body 21. Figure 12Specifically, the top cover body 21 has a first side and a second side facing away from each other in its height direction. The first side faces the outside of the battery cell 100, and the second side faces the electrode group 3 inside the accommodating cavity. A boss is formed by bending the top cover body 21 along its length direction, thus forming a boss on the first side. This boss can be manufactured by a stamping process, and the bent shape of the boss helps to improve its processing stability. Correspondingly, a recess is formed on the second side of the top cover body 21 corresponding to the position of the boss, and this recess extends through the opposite sides of the top cover body 21 along its width direction.

[0114] Specifically, the top cover body 21 includes a base plate portion and a bent portion. The bent portion is connected to the base plate portion at both ends in the length direction of the top cover body 21. The bent portion is bent relative to the base plate portion to form a boss, and two pole posts 22 are correspondingly inserted into the two base plate portions.

[0115] Understandably, in the protruding direction of the boss, the cross-sectional area of ​​multiple protrusions decreases sequentially, forming a stepped boss, with the topmost protrusion having an exhaust port 214 for installing the explosion-proof valve 23. When the boss is formed by stamping, it can be formed by multiple stamping processes, which can reduce the height of a single stamping, avoid sheet metal breakage, and ensure the structural strength of the boss.

[0116] like Figure 12 As shown, taking a boss with two protrusions as an example, the two protrusions are a first protrusion 211 and a second protrusion 212. The second protrusion 212 protrudes from the upper surface of the first protrusion 211, and the upper surface of the first protrusion 211 is connected to the battery pack housing support. A vent 214 is provided on the second protrusion 212. The second protrusion 212 is located at the middle of the first protrusion 211 along the length of the top cover body 21, which facilitates stamping. Furthermore, the first protrusion 211 can be connected to the battery pack housing support through its portions located on both sides of the second protrusion 212 to provide more stable support.

[0117] like Figure 12 As shown, in some embodiments of the present invention, the boss is provided with ribs 213, which extend from one protrusion to another. It can be understood that a portion of the rib 213 is connected to one protrusion and another portion is connected to another protrusion. The rib 213 connects at least two adjacent protrusions to locally reinforce multiple protrusions and improve the overall impact resistance of the boss.

[0118] like Figure 12 , Figure 16 and Figure 18 As shown, the top cover assembly 2 in this embodiment also includes an insulating member 24. The insulating member 24 is disposed on the side of the top cover body 21 away from the boss, and the insulating member 24 has an exhaust structure opposite to the exhaust port 214, and the pole post 22 passes through the insulating member 24.

[0119] When the top cover assembly 2 is installed in the housing, the insulating member 24 is located between the top cover body 21 and the electrode group 3, serving as insulation between them. The electrode post 22 passes through both the top cover body 21 and the insulating member 24, with one end of the electrode post 22 located on the side of the insulating member 24 away from the top cover body 21, for connection to the electrode tab 35 of the electrode group 3. The vent 214 communicates with the venting structure, allowing gas inside the cell 100 to be discharged through the explosion-proof valve 23.

[0120] Furthermore, such as Figure 13 As shown, a recess 241 is formed on the side of the insulating member 24 away from the top cover body 21, corresponding to the position of the boss. The recess 241 is adapted to accommodate the tabs 35 of the electrode assembly. The top cover assembly 2 also includes a connecting piece 25, which is connected to the pole post 22 and extends from the pole post 22 into the recess 241. The connecting piece 25 located in the recess 241 is used to connect the tabs 35.

[0121] like Figure 16 and Figure 18 As shown, in some embodiments of the present invention, the insulating member 24 includes a fixing plate 242 and a folding plate 243. The fixing plate 242 is located on the side of the top cover body 21 away from the boss and has a support portion 2422 protruding towards the side away from the top cover body 21. The folding plate 243 is folded and connected to the support portion 2422, so that the folding plate 243 can be fastened or opened relative to the fixing plate 242. The pole post 22 passes through the top cover body 21 and the fixing plate 242 along the height direction of the top cover body 21, and is spaced apart from the boss and the support portion 2422 in the length direction of the top cover body 21. Wherein, when the folding plate 243 is fastened to the fixing plate 242, the folding plate 243 covers the pole post 22, and both the support portion 2422 and the folding plate 243 are adapted to abut against the pole group 3 of the cell 100.

[0122] Specifically, the fixing plate 242 has a fitting portion 2421 and a support portion 2422 protruding from the fitting portion 2421. The fitting portion 2421 is fitted to the top cover body 21, and the support portion 2422 protrudes from the fitting portion 2421 on the side away from the top cover body 21, that is, the support portion 2422 is a locally thickened portion on the fixing plate 242. The folding plate 243 and the support portion 2422 are arranged along the length direction of the top cover body 21, and one end of the folding plate 243 in the length direction is folded and connected to the support portion 2422. Optionally, in the length direction of the top cover body 21, the pole post 22 is located between the support portion 2422 and the boss.

[0123] In some alternative embodiments, the fixing plate 242 has two support portions 2422 spaced apart along the length of the top cover body 21. One end of the folding plate 243 is folded and connected to one support portion 2422, allowing the folding plate 243 to be fastened or opened relative to the fixing plate 242. When the folding plate 243 is fastened to the fixing plate 242, the other end of the folding plate 243 is connected to the other support portion 2422.

[0124] It is understood that this embodiment only provides one folding plate 243. When it is fastened to the fixed plate 242, the folding plate 243 is connected between the two support parts 2422, which simplifies the assembly steps of the top cover assembly 2 and the pole group 3.

[0125] The folding plate 243 has a folding connecting end and a free end opposite to each other along the length of the top cover body 21. The folding connecting end is folded and connected to one support part 2422, and the free end overlaps with another support part 2422. Specifically, the other support part 2422 is provided with a slot 24221. When the folding plate 243 is fastened to the fixing plate 242, the free end is located within the slot 24221. Optionally, the support part 2422 and the free end are engaged in a limiting fit along the width of the top cover body 21 to ensure accurate positioning of the fastening position of the folding plate 243.

[0126] In an embodiment where the top cover assembly 2 is provided with a folding plate 243, the folding plate 243 can be configured as a bent plate conformally to the fixed plate 242, so as to ensure that when the folding plate 243 is fastened to the fixed plate 242, a groove 241 is formed on the side of the insulating member 24 away from the top cover body 21.

[0127] like Figure 19 As shown, in some embodiments of the present invention, the folding plate 243 has a first plate 2431 and a second plate 2432. The first plate 2431 is folded and connected to the support portion 2422 and covers the base portion 251. The second plate 2432 is located in the groove and covers the extension portion 252. It can be understood that the first plate 2431 is located outside the groove, and the folding plate 243 extends from the support portion 2422 into the groove according to the shape of the fixing plate 242.

[0128] When the folding plate 243 is fastened to the fixing plate 242, the side of the first plate 2431 away from the fixing plate 242 is flush with the support portion 2422. After the top cover assembly 2 and the pole group 3 are assembled, the support portion 2422 and the first plate 2431 simultaneously abut against the end face of the pole group 3.

[0129] The fixing plate 242 has a first bonding plate 24211, a first connecting plate, a second bonding plate 24212, a second connecting plate, and a third bonding plate 24213 connected in sequence to form a stepped plate. A support portion 2422 protrudes from the first bonding plate 24211, and a connecting piece 25 extends from the first bonding plate 24211 to the second bonding plate 24212. The first bonding plate 24211 is bonded to the substrate portion, the second bonding plate 24212 is bonded to the top wall of the first protrusion 211, and the third bonding plate 24213 is bonded to the top wall of the second protrusion 212. The first connecting plate is opposite to the side wall of the first protrusion 211, and the second connecting plate is opposite to the side wall of the second protrusion 212. The two ends of the third bonding plate 24213 are symmetrically connected to each other and are sequentially linked with the second connecting plate, the second bonding plate 24212, the first connecting plate, and the first bonding plate 24211.

[0130] In an embodiment where the top cover assembly 2 has two folding plates 243, each folding plate 243 includes a first plate 2431 and a second plate 2432, and the two folding plates 243 are symmetrically arranged about the boss.

[0131] In an embodiment where the top cover assembly 2 includes a folding plate 243, the folding plate 243 comprises two first plates 2431, two second plates 2432, and a third plate 2433. Along the length of the top cover body 21, the two second plates 2432 are respectively connected to both ends of the third plate 2433, and the two first plates 2431 are correspondingly connected to the ends of the two second plates 2432 furthest from the third plate 2433. To prevent the folding plate 243 from affecting the exhaust of the explosion-proof valve 23, the third plate 2433 is provided with a second exhaust structure 2434 communicating with the first exhaust structure 2423.

[0132] like Figure 10 , Figure 11 and Figure 20 Taking a battery cell 100 with two electrode groups 3 as an example, the process of assembling the electrode group 3 with the insulating film 1 and the top cover assembly 2 is explained. First, a single electrode group 3 is assembled with the insulating film 1. The insulating film 1 is wrapped around the outside of the electrode assembly 3. The two tabs 35 of the electrode assembly 3 pass through the clearance holes 1121 of the second membrane body 112. The support platform 331 of the electrode assembly 3 extends into the receiving platform 1122, ensuring that the bottom plate 16 is located outside the box structure that wraps the insulating film 1 of the electrode assembly 3. Then, the electrode assembly 3 and the tabs 35 are flattened. The two electrode assemblies 3 covered with the insulating film 1 are placed on both sides of the top cover body along the width direction of the top cover body. The two tabs 35 are aligned with the two pole posts, and the tabs 35 are welded to the pole posts. Next, the two electrode assemblies 3 are rotated 90° away from the top cover assembly 2, so that the top cover assembly 2 is located on the side of the electrode assembly 3. Finally, the electrode assembly 3 covered with the insulating film 1 is installed into the housing 4, and the top cover assembly 2 is located at the opening end of the housing 4.

[0133] In this embodiment, the production line tests various parameters of the battery cell 100 to verify the technical effects of different data. The following parameters are changed sequentially: the thickness t5 of the end of the first membrane 111 or the third membrane 113 away from the second membrane 112; the thickness t3 of the fourth adhesive layer 17; the height t6 of the base plate 16; the distance t7 between the bottom of the arc-shaped groove and the end of the first membrane 111 or the third membrane 113 away from the second membrane 112; the width W1 of the fourth adhesive layer 17; the width W2 of the base plate 16; the distance W3 between the groove opening and the edge of the base plate 16; and the distance between adjacent arc-shaped grooves. The ratio of the spacing W4 at the slot end, the distance between the bottom of the arc-shaped groove and the end of the first membrane 111 or the third membrane 113 away from the second membrane 112 to the height of the bottom support plate 16 is t7 / t6, half of the difference between the width of the bottom support plate 16 and the width of the fourth adhesive layer 17 is (W2-W1) / 2, and the ratio of the length of the bottom support plate 16 abutting against the shell 4 to the width of the bottom support plate 16 is (2W3+W4) / W2. The battery cell 100 is simulated and analyzed.

[0134] As can be seen from Tables 1 and 2, when the structural design of the insulating film 1 meets the above requirements, there is no problem of glue overflow at the adhesive layer of the insulating film 1, the bottom support plate 16 has smooth air venting, the safety performance of the battery cell 100 is improved, and the assembly process of the battery cell 100 is shortened, production efficiency is improved, and equipment and labor input are saved.

[0135] Table 1

[0136] Table 2

[0137] Thirdly, this embodiment provides a battery pack, including: a busbar, a housing, and the battery cell 100 as described above.

[0138] The housing forms a receiving cavity, and multiple battery cells 100 are provided, with multiple battery cells 100 stacked in the receiving cavity; the busbar is connected to the terminals of the multiple battery cells 100.

[0139] Specifically, since the battery pack includes a cell 100, and the specific structure of the cell 100 is as described in the above embodiments, the battery pack shown in this embodiment includes all the technical solutions of the above embodiments. Therefore, it has at least all the beneficial effects achieved by all the technical solutions of the above embodiments, which will not be described in detail here.

[0140] Understandably, after the cells 100 are grouped together, the terminal of each cell 100 is welded to the tab on the busbar. The busbar connects the stacked cells 100 into groups, and the tab is fixedly connected to the battery pack housing through a heat-conducting layer. Since the support platform 331 of the electrode group 3 in this embodiment extends into the receiving platform 1122 of the second membrane 112, it limits the displacement of the electrode group 3 along the length and width directions of the cell 100, improving the fixing effect of the electrode group 3 within the cell 100, preventing insulation defects caused by the movement of the electrode group 3, and simultaneously increasing the capacity of the cell 100. Meanwhile, a bottom support plate 16 is provided at the end of the first membrane 111 or the third membrane 113 facing away from the second membrane 112, perpendicular to the first direction. When the insulating film 1 encloses the box structure, the bottom support plate 16 is located outside the box structure, improving the cell 100's casing yield and venting effect, and enhancing the safety performance of the cell 100.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An insulating film applied to a battery cell, characterized in that, include: The first membrane assembly includes a first membrane body, a second membrane body, and a third membrane body connected sequentially along a first direction. The second membrane body is provided with a clearance hole for the electrode tab to pass through. On the side of the clearance hole, the second membrane body forms a receiving platform that protrudes to one side, and the receiving platform is used to receive a support platform for the electrode assembly. The end of the first membrane body or the third membrane body opposite to the second membrane body is provided with a bottom support plate in a direction perpendicular to the first direction, and the bottom support plate has a venting structure. The second membrane group is connected to the first membrane group on both sides of the second direction. The second membrane group includes a first folding body, a second folding body and a third folding body distributed along the first direction. The first folding body is connected to the first membrane body, the second folding body is connected to the second membrane body, and the third folding body is connected to the third membrane body. The first membrane and the third membrane can be folded and connected relative to the second membrane, and the first folding body, the second folding body and the third folding body of each second membrane group can be folded and connected relative to the first membrane group, so that the first membrane group and the two second membrane groups form a box structure, and the bottom support plate is located on the outside of the box structure.

2. The insulating film according to claim 1, characterized in that, The first membrane includes a first wrapping portion and a second wrapping portion, the first wrapping portion being connected to the second membrane; the third membrane includes a third wrapping portion and a fourth wrapping portion, the third wrapping portion being connected to the second membrane. The second wrapping portion is foldable relative to the first wrapping portion, and the fourth wrapping portion is foldable relative to the third wrapping portion, such that the second wrapping portion and the fourth wrapping portion at least partially overlap and are opposite to the second film body, and the bottom support plate is located outside the second wrapping portion or the fourth wrapping portion.

3. The insulating film according to claim 1, characterized in that, The exhaust structure is provided in multiple ways, and the multiple exhaust structures are arranged in parallel and spaced apart along the first direction.

4. The insulating film according to claim 3, characterized in that, The exhaust structure is an arc-shaped groove, which extends along the length of the battery cell.

5. The insulating film according to claim 4, characterized in that, The thickness of the end of the first membrane or the third membrane away from the second membrane is t5, the height of the bottom support plate is t6, and the distance between the bottom of the arc-shaped groove and the end of the first membrane or the third membrane away from the second membrane is t7, satisfying: 0.08mm≤t5≤0.15mm, 0.8mm≤t6≤1.5mm, 0.3≤t7 / t6≤0.6; And / or, along the first direction, the distance between the groove opening end of the arc-shaped groove and the edge of the bottom support plate is W3, and the distance between the groove opening ends of adjacent arc-shaped grooves is W4, satisfying: W3≥2mm, W4≥2mm.

6. The insulating film according to claim 5, characterized in that, The first membrane or the third membrane has a fourth adhesive layer at the end opposite to the second membrane. The base plate is bonded and fixed to the end of the first membrane or the third membrane opposite to the second membrane through the fourth adhesive layer. The thickness of the fourth adhesive layer is t3, which satisfies: 0.1mm≤t3≤0.15mm.

7. The insulating film according to claim 6, characterized in that, Along the width direction of the battery cell, the width of the fourth adhesive layer is W1, and the width of the bottom support plate is W2, satisfying the following: 2.5mm≤(W2-W1) / 2≤5mm, 0.2≤(2W3+W4) / W2≤0.

35.

8. A battery cell, characterized in that, include: Top cover assembly, electrode assembly, housing, and insulating film as described in any one of claims 1 to 7; The housing has an opening, the top cover assembly is disposed in the opening and surrounds the housing to form a receiving cavity, the electrode group is disposed in the receiving cavity, and the insulating film is located between the electrode group and the housing; The electrode assembly has a first end face and a second end face facing away from each other, and two first side faces and two second side faces connected between the first end face and the second end face. The two first side faces are arranged facing away from each other, and the two second side faces are arranged facing away from each other. An electrode tab is connected to the first end face, and the electrode tab passes through the clearance hole. A support platform is formed on the side of the electrode tab on the first end face. The support platform is arranged opposite to the receiving platform. The second membrane body is wrapped around the first end face. The first membrane body and the third membrane body are respectively wrapped around the two first side faces and the second end face. The two second membrane assemblies are folded relative to the first membrane assembly and are wrapped around the two second side faces one by one.

9. The battery cell according to claim 8, characterized in that, Along the height direction of the battery cell, the height of the support platform of the electrode assembly is H1, and the height of the receiving platform is H2; along the length direction of the battery cell, the length of the support platform is L1, and the length of the receiving platform is L2; ​​satisfying: 0.5mm≤(L2-L1) / 2≤1mm, 0.2mm≤(H2-H1) / 2≤0.5mm.

10. A battery pack, characterized in that, include: Busbar, housing, and battery cell as described in any one of claims 8 to 9; The housing forms a receiving cavity, and multiple battery cells are provided, with the multiple battery cells stacked in the receiving cavity; the busbar is connected to the terminals of the multiple battery cells.

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