Insulating film and battery cell

Abstract

The invention relates to the technical field of batteries, and provides an insulating film and a battery cell, the insulating film is used for wrapping the outer side of a pole group of the battery cell, the insulating film comprises a first film group, a second film group and a third film group, the first film group comprises a first film body, a second film body and a third film body, the first film body, the second film body and the third film body are sequentially connected along a first direction, and the second film body is provided with step-shaped raised parts and via holes which are arranged at intervals in a second direction; the first direction is perpendicular to the second direction; the two ends, in the second direction, of the first film set are each connected with a second film set, each second film set comprises a first turnover body, a second turnover body and a third turnover body which are distributed in the first direction, the first turnover bodies are connected with the first film bodies, the second turnover bodies are connected with the second film bodies, and the third turnover bodies are connected with the third film bodies; the first film body and the third film body can be folded relative to the second film bodies and connected with each other, and 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 with each other, so that the first film group and the two second film groups define a box body structure.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to an insulating film and a battery cell. 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 cell housing, a cell cover, and an electrode assembly, which is located within a cavity formed by the cell housing and the cell cover.

[0003] The cell cover includes a cover body, electrode posts, and an insulating component. The electrode posts are disposed on the cover body, which is welded and sealed to the cell housing. The insulating component is located between the cover body and the electrode assembly, defining a space for accommodating the electrode assembly's tabs. An insulating film is wrapped around the outside of the electrode assembly to achieve insulation between the electrode assembly and the cell housing. In traditional cell structures, the insulating film and the insulating component are fixed by heat fusion. However, in some cell structures, the insulating component is relatively thin, resulting in a low fixation yield with the insulating film and affecting the cell's performance. Summary of the Invention

[0004] This invention provides an insulating film and a battery cell to solve the problem of low yield rate of insulating film fixation in existing battery cells.

[0005] This invention provides an insulating film for wrapping the outer side of the electrode assembly of 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 has stepped protrusions and through holes spaced apart in a second direction. The stepped protrusions are adapted to cover the stepped protrusions on the end face of the electrode assembly, and the through holes are adapted to allow the tabs of the electrode assembly to pass through. The first direction and the second direction are perpendicular. The second membrane group is connected to the first membrane group at both ends in the second direction. The second membrane group includes a first folded body, a second folded body and a third folded body distributed along the first direction. The first folded body is connected to the first membrane body, the second folded body is connected to the second membrane body, and the third folded 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.

[0006] According to an insulating film provided by the present invention, the first film body includes a first wrapping portion and a second wrapping portion connected together, 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 connected together, 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 the overlapping portion is opposite to the second film.

[0007] According to an insulating film provided by the present invention, the second wrapping portion includes a fourth folding body and a fifth folding body connected in the first direction, the fourth folding body being connected to the first wrapping portion; the fifth folding body is foldable relative to the fourth folding body, so that the fifth folding body is connected to the third wrapping portion and opposite to the first wrapping portion.

[0008] According to an insulating film provided by the present invention, the inner side of the fifth folded body is provided with an adhesive layer, and the fifth folded body can be bonded to the third wrapping part through the adhesive layer; And / or, the extension length of the fifth folding body relative to the fourth folding body in the first direction is h, where 10mm ≤ h ≤ 20mm.

[0009] According to an insulating film provided by the present invention, the stepped raised portion includes a first raised portion and a second raised portion connected sequentially in a second direction, wherein the raised height of the first raised portion is greater than the raised height of the second raised portion; Wherein, the wall thickness of the top wall of the first raised portion and the second raised portion is T1, the wall thickness of other areas is T2, the raised height of the first raised portion is H1, the raised height of the second raised portion is H2, 0.25mm≤T1≤0.35mm, 0.08mm≤T2≤0.15mm, H1 / T1≤20, H2 / T1≤8; and / or, the top wall of the first raised portion is provided with an inlet for the electrolyte to pass through.

[0010] The present invention also provides a battery cell, comprising: The battery cell casing has an opening; A battery cell cover plate includes a cover plate body, the cover plate body being disposed at the opening and surrounding the battery cell housing to form a receiving cavity, the cover plate body having a protrusion on the side away from the receiving cavity, and the battery cell cover plate having a stepped groove on the side facing the receiving cavity corresponding to the position of the protrusion; An electrode assembly is disposed within the receiving cavity and has a first end face and a second end face facing away from each other, as well as 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. A stepped protrusion is provided on the first end face. The electrode lug of the electrode assembly is connected to the first end face, and the stepped protrusion is received in the stepped groove. As described above, an insulating film is located between the electrode group and the cell housing. The second film wraps around the first end face. The first film and the third film respectively wrap around the two first side faces and the second end face. The two second film groups are folded relative to the first film group and wrapped around the two second side faces one by one. The stepped protrusion covers the stepped convex portion. The electrode tab passes through the through hole.

[0011] According to a battery cell provided by the present invention, the battery cell cover plate further includes an electrode post, and the boss includes a first support platform, a mounting platform and a second support platform arranged along the length direction of the cover plate body. The mounting platform is connected between the first support platform and the second support platform. The electrode post passes through the cover plate body and protrudes from the mounting platform. The side of the battery cell cover plate facing the receiving cavity has a first sink groove, a third sink groove and a second sink groove respectively formed at the positions of the first support platform, the mounting platform and the second support platform. The first sink groove and the third sink groove are connected to form the stepped sink groove, and the second sink groove is connected to the third sink groove. The stepped protrusion includes a first protrusion and a second protrusion connected in the length direction. The first protrusion is received in the first sinker, the second protrusion is received in the third sinker, and the electrode tab is received in the second sinker.

[0012] According to a battery cell provided by the present invention, the number of electrode groups is two, each electrode group corresponds to one insulating film, the electrode group has the electrode tab, the stepped protrusion is flush with one of the first side surfaces and has a gap with the other first side surface, one first side surface of the two electrode groups is abutted, such that two stepped protrusions opposite each other in the width direction are abutted to form a stepped convex hull, the stepped convex hull is received in the stepped groove and is limited and matched with the first groove.

[0013] According to a battery cell provided by the present invention, there are two mounting platforms and two second support platforms, with the first support platform located between the two second support platforms, and the two mounting platforms respectively disposed on both sides of the first support platform, with each mounting platform having a terminal post inserted through it.

[0014] According to a battery cell provided by the present invention, the battery cell cover plate further includes an insulating member, the insulating member is disposed on the side of the cover plate body near the electrode group, the electrode post passes through the insulating member, and the side of the cover plate body near the electrode group forms a groove corresponding to the positions of the first support platform, the mounting platform and the second support platform; The insulating component engages with the groove, and the side of the insulating component away from the cover plate body forms the first recess, the second recess, and the third recess respectively, corresponding to the positions of the first support platform, the mounting platform, and the second support platform.

[0015] The insulating film battery cell provided by this invention, by setting a first film group and two second film groups connected to the first film group, utilizes the first film group to wrap around two end faces and two opposite sides of the electrode group, and utilizes the first, second, and third folding bodies of the second film group to fold relative to the first film group to wrap around the other two opposite sides of the electrode group, thus achieving full wrapping of all six sides of the square electrode group. This eliminates the need for heat-sealing the insulating film to the insulating components on the battery cell cover, preventing the adverse effects on battery cell performance caused by low heat-sealing yield of the insulating film and insulating components. Simultaneously, it improves the insulation of the insulating film inside the battery cell, reducing the risk of short circuits between the electrode group and the casing. Attached Figure Description

[0016] 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.

[0017] Figure 1 This is a schematic diagram of the structure of the insulating film provided by the present invention.

[0018] Figure 2 This is a schematic diagram of the insulating film provided by the present invention in a folded state.

[0019] Figure 3 This is a schematic diagram from another perspective of the insulating film provided by the present invention in a folded state.

[0020] Figure 4 This is a schematic diagram of the battery cell provided by the present invention.

[0021] Figure 5 This is a schematic diagram of the assembly of the cell cover plate, electrode group and insulating film in the battery cell provided by the present invention.

[0022] Figure 6 This is a cross-sectional view of the assembly structure of the electrode group and the cell cover plate of the battery cell provided by the present invention.

[0023] Figure 7 This is one of the structural schematic diagrams of the battery cell cover plate provided by the present invention.

[0024] Figure 8 This is a schematic diagram of the structure of the cover plate body in the battery cell provided by the present invention.

[0025] Figure 9 This is the second schematic diagram of the structure of the battery cell cover plate provided by the present invention.

[0026] Figure 10 This is a partial structural cross-sectional view of the battery cell cover plate provided by the present invention.

[0027] Figure 11 This is one of the structural schematic diagrams of the electrode assembly in the battery cell provided by the present invention.

[0028] Figure 12 This is the second schematic diagram of the structure of the electrode assembly in the battery cell provided by the present invention.

[0029] Figure 13 This is a partial structural schematic diagram of the electrode group unit in the battery cell provided by the present invention.

[0030] Figure 14 This is one of the schematic diagrams showing the wrapping of the insulating film and the electrode assembly provided by the present invention.

[0031] Figure 15 This is the second schematic diagram of the insulating film and electrode assembly provided by the present invention.

[0032] Figure label: 1. Cover plate body; 101. First groove; 102. Second groove; 103. Third groove; 10. Substrate; 11. First support platform; 12. Second support platform; 13. Mounting platform; 2. Terminal post; 3. Insulating component; 301. First recess; 302. Second recess; 303. Third recess; 4. Insulating film; 41. First membrane assembly; 411. First membrane body; 4111. First wrapping part; 4112. Second wrapping part; 41121. Fourth folding body; 41122. Fifth folding body; 412. Second membrane body; 4121. First raised part; 4122. Second raised part; 4 123. Through hole; 413. Third membrane body; 4131. Third wrapping part; 4132. Fourth wrapping part; 42. Second membrane assembly; 421. First folding body; 422. Second folding body; 423. Third folding body; 43. Adhesive layer; 5. Connecting piece; 51. Welding part; 52. Base part; 53. Connecting part; 6. Cell housing; 7. Electrode assembly; 701. First protrusion; 702. Second protrusion; 703. First end face; 704. First side face; 705. Second side face; 71. First convex bud; 72. Second convex bud; 74. Electrode tab; 741. Root section; 742. Closing section. Detailed Implementation

[0033] 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.

[0034] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "first" and "second" are numbered for the purpose of clearly identifying product components and do not represent any substantial difference. The terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances. Furthermore, "multiple" means two or more. In the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0035] The following is combined with Figures 1-15 The insulating film and battery cell of the present invention are described.

[0036] like Figures 1-3 As shown, the insulating film 4 provided in this embodiment of the invention is used to wrap the outside of the electrode assembly 7 of the battery cell, and includes a first film assembly 41 and a second film assembly 42. The first module includes a first film body 411, a second film body 412 and a third film body 413 connected sequentially along a first direction. The second film body 412 has stepped raised portions and through holes 4123 spaced apart in a second direction. (The stepped raised portion can be referred to...) Figure 1 The first raised portion 4121 and the second raised portion 4122 are adapted to cover the stepped protrusion on the end face of the electrode assembly 7, and the through hole 4123 is adapted to allow the tab 74 of the electrode assembly 7 to pass through. The first direction and the second direction are perpendicular. A second membrane assembly 42 is connected to each end of the first membrane assembly 41 in the second direction. The second membrane assembly 42 includes a first folded body 421, a second folded body 422 and a third folded body 423 distributed along the first direction. The first folded body 421 is connected to the first membrane body 411, the second folded body 422 is connected to the second membrane body 412, and the third folded body 423 is connected to the third membrane body 413.

[0037] The first membrane 411 and the third membrane 413 can be folded and connected relative to the second membrane 412 respectively. The first folding body 421, the second folding body 422 and the third folding body 423 of each second membrane group 42 can be folded and connected relative to the first membrane group 41, so that the first membrane group 41 and the two second membrane groups 42 form a box structure.

[0038] The insulating film 4 provided by this invention is applied to a square battery cell to wrap around the outside of a square electrode assembly 7 with a protrusion at one end. During battery cell assembly, the insulating film 4 is a pre-cut sheet insulating film 4 with stepped protrusions.

[0039] It is understandable that the two second membrane groups 42 are respectively connected to the two sides of the first membrane group 41, the two sides of the first membrane 411 are respectively connected to a first folding body 421, the two sides of the second membrane 412 are respectively connected to a second folding body 422, and the two sides of the third membrane 413 are respectively connected to a third folding body 423.

[0040] like Figure 11 As shown, the electrode assembly 7 has a first end face 703 and a second end face facing away from each other, and two first side faces 704 and two second side faces 705 connected between the first end face 703 and the second end face. The two first side faces 704 are arranged facing away from each other, and the two second side faces 705 are arranged facing away from each other. The first end face 703 has a protrusion and is connected to an electrode tab 74.

[0041] See Figure 2 , Figure 11 , Figure 14 and Figure 15 As shown, when the insulating film 4 is wrapped around the electrode assembly 7, the second film 412 can be wrapped around the first end face 703, while the stepped protrusion covers the stepped convex portion, and the electrode tab 74 passes through the through hole 4123. The first film 411 and the third film 413 are both folded relative to the second film 412, so that the first film 411 wraps around at least a portion of a first side face 704 and a second end face, and the third film 413 wraps around at least a portion of another first side face 704 and a second end face. Then, the first folding body 421 of one of the second membrane groups 42 is folded relative to the first membrane body 411, the second folding body 422 is folded relative to the second membrane body 412, and the third folding body 423 is folded relative to the third membrane body 413. The first folding body 421, the second folding body 422, and the third folding body 423 are stacked on one second side surface 705. Similarly, the first folding body 421, the second folding body 422, and the third folding body 423 of the other second membrane group 42 are stacked on another second side surface 705.

[0042] It is understood that the insulating film 4, through the aforementioned folded cuboid box structure, is used to wrap around the six sides of the electrode assembly 7. The first film 411 and the third film 413 can be fixedly connected by adhesive, as can the first folded body 421, the second folded body 422, and the third folded body 423.

[0043] In traditional technology, the insulating film 4 is only covered on the four sides of the electrode group 7. The insulating film 4 needs to be thermally fused to the insulating component 3 on the cell cover. If the thickness of the insulating component 3 is too thin, it will reduce the yield of the thermal fusion fixation between the insulating film 4 and the insulating component 3, and affect the performance of the cell.

[0044] The insulating film 4 for the battery cell provided in this embodiment of the invention, by setting a first film group 41 and two second film groups 42 connected to the first film group 41, utilizes the first film group 41 to wrap two end faces and two opposite sides of the electrode group 7, and utilizes the first folding body 421, the second folding body 422, and the third folding body 423 of the second film group 42 to fold relative to the first film group 41 to wrap the other two opposite sides of the electrode group 7, thereby achieving wrapping of all six sides of the square electrode group 7. This eliminates the need for heat-fusion fixing of the insulating film 4 to the insulating component 3 on the battery cell cover, preventing the adverse effects on battery cell performance caused by low heat-fusion yield of the insulating film 4 and the insulating component 3. Simultaneously, it improves the insulation of the insulating film 4 inside the battery cell, reducing the risk of short circuit between the electrode group 7 and the casing.

[0045] In this embodiment of the invention, a crease is provided at the connection between the first membrane 411 and the second membrane 412, and a crease is provided at the connection between the third membrane 413 and the second membrane 412. A crease is provided at the connection between the first folding body 421 and the first membrane 411, a crease is provided at the connection between the second folding body 422 and the second membrane 412, and a crease is provided at the connection between the third folding body 423 and the third membrane 413. The insulating film 4 can be permanently creased using mechanical indentation or thermal indentation methods to facilitate the wrapping of the electrode assembly 7 with the insulating film 4.

[0046] like Figure 1 As shown, in some embodiments of the present invention, the first membrane 411 includes a first wrapping portion 4111 and a second wrapping portion 4112 connected together. The first wrapping portion 4111 is connected to the second membrane 412. The third membrane 413 includes a third wrapping portion 4131 and a fourth wrapping portion 4132 connected together, with the third wrapping portion 4131 connected to the third membrane 413. The second wrapping portion 4112 is foldable relative to the first wrapping portion 4111, and the fourth wrapping portion 4132 is foldable relative to the third wrapping portion 4131, such that the second wrapping portion 4112 and the fourth wrapping portion 4132 at least partially overlap, and the overlapping portion is opposite to the second membrane 412.

[0047] The first wrapping portion 4111 is foldable relative to the second membrane 412 to cover a first side surface 704. The third wrapping portion 4131 is foldable relative to the second membrane 412 to cover another first side surface 704 of the electrode assembly 7. The second wrapping portion 4112 is folded relative to the first wrapping portion 4111 and covers at least a portion of the second end face. The fourth wrapping portion 4132 is folded relative to the third wrapping portion 4131 and covers at least a portion of the second end face. At least a portion of the second wrapping portion 4112 and at least a portion of the fourth wrapping portion 4132 overlap the second end face.

[0048] Optionally, a crease is provided at the connection between the first wrapping part 4111 and the second wrapping part 4112, and a crease is provided at the connection between the third wrapping part 4131 and the fourth wrapping part 4132. This crease can be formed by mechanical indentation or thermal indentation.

[0049] like Figure 1 As shown, in some embodiments, the second wrapping portion 4112 includes a fourth folding body 41121 and a fifth folding body 41122 connected in a first direction. The fourth folding body 41121 is connected to the first wrapping portion 4111. The fifth folding body 41122 is foldable relative to the fourth folding body 41121, so that the fifth folding body 41122 is connected to the third wrapping portion 4131 and opposite to the first wrapping portion 4111.

[0050] Understandably, when the first wrapping portion 4111 and the third wrapping portion 4131 are folded relative to the second membrane 412, and the fourth folding body 41121 is folded relative to the first wrapping portion 4111 to be opposite to the second membrane 412, the fifth folding body 41122 can be folded relative to the fourth folding body 41121 to fit against the third wrapping portion 4131. This facilitates the connection of the tail ends of the first membrane 411 and the second membrane 412, while also achieving good wrapping of the bottom of the electrode assembly, making it easier for the electrode assembly 7 to be inserted into the housing.

[0051] Furthermore, combined Figure 2 The inner surface of the fifth folding body 41122 is provided with an adhesive layer 43, which allows the fifth folding body 41122 to be bonded to the third wrapping part 4131. Optionally, the adhesive layer 43 extends along the second direction to achieve good adhesion to the third wrapping part 4131. Of course, the outer surfaces of the fifth folding body 41122 and the third wrapping part 4131 can also be bonded together with adhesive tape.

[0052] Optionally, the extension length of the fifth folding body 41122 relative to the fourth folding body 41121 in the first direction is h, where 10mm ≤ h ≤ 20mm. If the value of h is too small, the contact area between the fifth folding body 41122 and the third wrapping part 4131 is too small, making it inconvenient to perform the wrapping and bonding operation when using adhesive tape, and the area of ​​the adhesive layer 43 on the inner side of the fifth folding body 41122 is insufficient. If the value of h is too large, it increases the material cost.

[0053] In some embodiments, the fourth wrapping portion 4132 is provided with a plurality of vent holes (not shown in the figure), and the fourth folding body 41121 is used to be stacked on the outside of the fourth wrapping portion 4132. It is understood that the gas in the electrode assembly 7 can be discharged to the outside of the fourth wrapping portion 4132 through the plurality of vent holes, and then discharged from the insulating film 4 between the fourth wrapping portion 4132 and the fourth folding body 41121, thereby reducing the heat accumulation of the electrode assembly 7.

[0054] like Figure 1 and Figure 2 As shown in the embodiment of the present invention, the stepped raised portion includes a first raised portion 4121 and a second raised portion 4122 connected sequentially in the second direction, and the raised height of the first raised portion 4121 is greater than the raised height of the second raised portion 4122.

[0055] Optionally, the top wall of the first raised portion 4121 is provided with an inlet for the passage of electrolyte. Correspondingly, the cell cover plate may be provided with an injection port (not shown in the figure) at the position corresponding to the inlet, so as to inject electrolyte into the electrode assembly 7 after the cell is assembled.

[0056] Optionally, the wall thickness of the top wall of the first raised portion 4121 and the second raised portion 4122 is T1, and the wall thickness of other areas is T2. The raised height of the first raised portion 4121 is H1, and the raised height of the second raised portion 4122 is H2. 0.25mm≤T1≤0.35mm, 0.08mm≤T2≤0.15mm, H1 / T1≤20, H2 / T1≤8.

[0057] The top walls of the first raised portion 4121 and the second raised portion 4122 are thicker than those of other areas, resulting in higher hardness of the top walls. This helps maintain their shape and improves their insulation, while also maintaining good flexibility in other areas. If the T1 value is too small, the hardness is insufficient, the insulation is poor, and insulation defects are likely to occur. If the T1 value is too large, it affects the stamping yield. If the T2 value is too small, the insulating film 4 is too thin, resulting in poor insulation and making it difficult to achieve the desired top wall thickness. If the T2 value is too large, the flexibility is poor, and the material cost of the insulating film 4 is increased.

[0058] During the assembly of the cell cover and electrode group 7, a thicker top wall with greater hardness can provide good protection and insulation for the stepped protrusions of the electrode group 7. The first raised portion 4121 and the second raised portion 4122 of the insulating film 4 can be formed by stamping, and their raised height will affect the thickness of their top wall. When the T1 value is constant, if H1 and H2 are too large, it will affect the stamping yield of the stepped raised portion. If the material thickness of the first raised portion 4121 and the second raised portion 4122 is insufficient, poor insulation is likely to occur.

[0059] Optionally, the insulating film 4 is made of PP (Polypropylene) material with a tensile strength ≥50 MPa, an elastic modulus E ≥1100 MPa, and an elongation A ≥85%, to meet the requirements for stamping the first raised portion 4121 and the second raised portion 4122.

[0060] like Figures 4-6 As shown, this embodiment of the invention also provides a battery cell, including a battery cell housing 6, a battery cell cover plate, an electrode assembly 7, and an insulating film 4 as described in any of the above embodiments. The battery cell housing 6 has an opening. The battery cell cover plate includes a cover plate body 1. The cover plate body 1 is disposed at the opening and surrounds the battery cell housing 6 to form a receiving cavity. A boss is provided on the side of the cover plate body 1 away from the receiving cavity. A stepped groove is formed on the side of the battery cell cover plate facing the receiving cavity, corresponding to the position of the boss.

[0061] The pole group 7 is disposed within the receiving cavity. See also Figure 11 The electrode assembly 7 has a first end face 703 and a second end face facing away from each other, and two first side faces 704 and two second side faces 705 connecting the first end face 703 and the second end face. The two first side faces 704 are arranged facing away from each other, and the two second side faces 705 are arranged facing away from each other. The first end face 703 has a stepped protrusion, and the electrode tabs 74 of the electrode assembly 7 are connected to the first end face 703. The stepped protrusion is received in a stepped groove. The insulating film 4 is located between the electrode assembly 7 and the cell housing 6. The second film 412 is wrapped around the first end face 703, and the first film 411 and the third film 413 are respectively wrapped around the two first side faces 704 and the second end face. The two second film groups 42 are folded relative to the first film group 41 and are wrapped around the two second side faces 705 one by one. The stepped protrusion covers the stepped protrusion, and the electrode tabs 74 pass through the through hole 4123.

[0062] The cell housing 6 is a cavity structure with an opening on one side. The cover plate body 1 is welded to the cell housing 6 to form the outer shell of the cell, providing protection for the internal components and withstanding certain external impacts. The electrode group 7 is formed by stacking multiple electrode sheets in the width direction of the cover plate body 1. Each electrode sheet has a protrusion at one end corresponding to the tab 74, and the protrusions of multiple electrode sheets are stacked to form a stepped protrusion.

[0063] The battery cell provided in this embodiment of the invention eliminates the adverse effects of low heat-fusion yield of the insulating film 4 and the insulating component 3 on the battery cell performance, improves the insulation of the insulating film 4 inside the battery cell, and reduces the risk of short circuit between the electrode assembly 7 and the casing. Simultaneously, by forming a stepped groove on the side of the battery cell cover facing the receiving cavity corresponding to the protrusion, the internal space of the battery cell is expanded. The stepped protrusion is accommodated within the stepped groove, increasing the volume of the electrode assembly 7 and thus increasing the battery cell capacity.

[0064] In traditional battery pack structures, the battery pack relies solely on the casing to withstand external impacts. However, the casing plate opposite the terminal 2 has a large area, making it prone to deformation if its rigidity is insufficient. To prevent casing deformation from causing compression damage to the busbar and terminal 2, a large space needs to be reserved between the busbar and the casing in the structural design, with supporting foam installed between them. Some designs also incorporate concave and convex structures on the casing plate to enhance rigidity and prevent deformation. However, these measures result in a large gap between the cells and the casing, wasting space. Increasing the casing thickness to increase rigidity would increase the weight of the battery pack, hindering lightweight design. Furthermore, the heat from the cell cover is dissipated only through conduction between the terminal 2 and the busbar, and through its own thermal radiation, resulting in low heat dissipation efficiency and easy heat accumulation.

[0065] It should be noted that the battery cell has two terminals 2, namely a positive terminal and a negative terminal. In this embodiment of the invention, the number of terminals 2 on the battery cell cover can be one or two. The number of mounting platforms 13 can be determined based on the number of terminals 2, with each terminal 2 corresponding to one mounting platform 13.

[0066] like Figure 7 and Figure 9 As shown, in some embodiments, the cell cover plate further includes a terminal post 2. The boss includes a first support platform 11, a mounting platform 13, and a second support platform 12 arranged along the length of the cover plate body 1. The mounting platform 13 is connected between the first support platform 11 and the second support platform 12. The terminal post 2 passes through the cover plate body 1 and protrudes from the mounting platform 13. The terminal post 2 is connected to a tab 74. On the side of the cell cover plate facing the receiving cavity, corresponding to the positions of the first support platform 11, the mounting platform 13, and the second support platform 12, a first recess 301, a third recess 303, and a second recess 302 are formed, respectively. The first recess 301 and the third recess 303 are connected to form a stepped recess, and the second recess 302 is connected to the third recess 303. The stepped protrusion includes a first protrusion 701 and a second protrusion 702 connected in the length direction of the cover plate body 1. The first protrusion 701 is received in the first sink 301, the second protrusion 702 is received in the third sink 303, and the tab 74 is received in the second sink 302.

[0067] The terminal post 2 protrudes from the outer surface of the cover plate body 1 to form a terminal post 2 terminal, which is used to connect with the busbar so that multiple cells can be connected through the busbar to form a battery module. The other end of the terminal post 2 is located in the receiving cavity and is connected to the tab 74 of the electrode group 7. The battery module is assembled in the housing to form a battery pack. Each electrode piece has a first protrusion and a second protrusion at one end corresponding to the tab 74. The first protrusions of multiple electrode pieces are stacked to form a first protrusion 701, and the second protrusions of multiple electrode pieces are stacked to form a second protrusion 702.

[0068] For the length and width directions of the cover plate body 1, see [reference]. Figure 4 The thickness direction of the cover plate body 1 is perpendicular to the length and width directions. Specifically, the cover plate body 1 has a first side and a second side that are opposite to each other in its thickness direction. The first side faces the outside of the battery cell and is provided with a first support platform 11, a second support platform 12, and a mounting platform 13. The mounting platform 13 is provided with a through hole 132 penetrating the cover plate body 1. The electrode post 2 passes through the through hole 132 and protrudes from the mounting platform 13. One end of the electrode post 2 protruding from the mounting platform 13 forms a terminal of the electrode post 2. The second side faces the electrode group 7 inside the receiving cavity.

[0069] The first support platform 11 and the second support platform 12 of the boss are adapted to be connected to the battery pack housing for support. In the battery pack's operating state, the first support platform 11 and the second support platform 12 can be located on the top or side of the battery cell and abut against the housing to bear the impact force transmitted from the housing. The part of the housing connected to the boss for support can be the housing shell; alternatively, the housing includes a shell and a cold plate, with the cold plate located between the shell and the battery cell, and the boss connected to the cold plate for support. The top surface of the boss can be coated with structural adhesive to bond it to the housing, ensuring good contact and thermal conductivity between the boss and the housing.

[0070] The first support platform 11, the second support platform 12, and the mounting platform 13 are arranged along the length of the cover plate body 1. Correspondingly, the first protrusion 71, the second protrusion 72, and the electrode ear 74 on the electrode assembly 7 are arranged along the length of the cover plate body 1. In the thickness direction of the cover plate body 1, the first support platform 11 is opposite to the first protrusion 71, the second support platform 12 is opposite to the electrode ear 74, and the mounting platform 13 is opposite to the second protrusion 72.

[0071] It can be understood that the first support platform 11, the mounting platform 13 and the second support platform 12 are connected to form an integral boss, and the first sink 301, the third sink 303 and the second sink 302 are connected to form an integral sink. The first support platform 11 and the mounting platform 13 are connected to form a stepped boss. Correspondingly, the first sink 301 and the third sink 303 are connected to form a stepped sink. The first convex portion 701 is received in the first sink 301, and the second convex portion 702 is received in the third sink 303, increasing the volume of the electrode group 7. The electrode tab 74 is received in the second sink 302, increasing the space utilization rate inside the battery cell housing 6, enabling a larger space to be provided inside the battery cell for arranging the electrode group body, and further increasing the capacity of the battery cell.

[0072] In an embodiment of the present invention, the cover body 1 has a reference surface, and the first support platform 11, the second support platform 12 and the mounting platform 13 protrude from the reference surface. Optionally, the protruding height of the first support platform 11 and the second support platform 12 relative to the reference surface is greater than the protruding height of the end of the pole 2 protruding from the mounting platform 13 relative to the reference surface, so as to reserve a certain space between the pole 2 and the box body for arranging the bus bar.

[0073] Specifically, referring to Figure 7 , the cover body 1 includes a substrate 10, a first support platform 11, a second support platform 12 and a mounting platform 13. The first support platform 11, the second support platform 12 and the mounting platform 13 are connected to the substrate 10 and protrude from the substrate 10 along the thickness direction of the cover body 1. The reference surface of the cover body 1 is formed on the substrate 10.

[0074] It can be understood that the height of the first support platform 11 and the second support platform 12 relative to the reference surface is greater than the height of the mounting platform 13 relative to the reference surface. Correspondingly, the height of the first convex portion 701 relative to the first end face 703 is greater than the height of the second convex portion 702 relative to the first end face 703. When the number of the mounting platform 13 and the second support platform 12 is two, the two second convex portions 702 are respectively arranged on both sides of the first convex portion 701, forming a "convex"-shaped stepped convex portion. Correspondingly, the two second convex packages 72 are respectively arranged on both sides of the first convex package 71, forming a "convex"-shaped stepped convex package.

[0075] The battery cell provided in this embodiment of the invention features a protrusion on the cover plate body 1. This protrusion is used to support and connect with the battery pack housing, allowing the cell's outer shell to also function as a load-bearing component. This prevents significant deformation of the housing, reduces its thickness, and lightens the battery pack weight. Furthermore, while ensuring the housing does not cause compression damage to the busbars and terminals 2, it reduces the distance between the busbars and the housing, thereby increasing the cell's volume, fully utilizing the internal space of the housing, improving the battery pack's energy density, and increasing the cell's capacity. The cell's heat can be transferred to the housing through the protrusion, improving its heat dissipation efficiency. The mounting platform 13 on the cover plate body 1 increases the structural strength of the area corresponding to the terminals 2, reducing the risk of short circuits caused by deformation of the cover plate body 1 under impact that could compress the terminals 2.

[0076] like Figure 7 As shown, in some embodiments, there are two mounting platforms 13 and two second support platforms 12. The first support platform 11 is located between the two second support platforms 12, and the two mounting platforms 13 are respectively disposed on both sides of the first support platform 11. Each mounting platform 13 is provided with a pole post 2. There are two second protrusions 702, which are respectively disposed on both sides of the first protrusion 701.

[0077] Understandably, the battery cell cover plate has a first support platform 11 and a second support platform 12 on both sides corresponding to each terminal post 2, which are connected to the battery pack housing for support and protection, reducing the risk of pressure on the terminal post 2. Optionally, the first support platform 11 and the second support platform 12 are at the same height relative to the reference plane, so that the first support platform 11 and the second support platform 12 are connected to the housing on the same plane.

[0078] The first support platform 11, the second support platform 12, and the mounting platform 13 all have a top wall and side walls connected to the top wall. For example... Figure 10 As shown, in some embodiments, the angle between the sidewalls of the first support platform 11, the second support platform 12, and the mounting platform 13 and the reference plane is 90°+β, where 15°≤β≤25°. This helps ensure the manufacturability, structural strength, and uniform stress distribution of the first support platform 11, the second support platform 12, and the mounting platform 13, thereby improving production yield. Given the limited size of the cover plate body 1, this also increases the accommodating space of the first settling tank 301, the second settling tank 302, and the third settling tank 303. If the angle is too small, it is not conducive to the stamping process and easily causes significant stress concentration; if the angle is too large, the impact resistance is insufficient, and the first support platform 11, the second support platform 12, and the mounting platform 13 occupy a large area, which is not conducive to structural layout.

[0079] like Figure 5 and Figure 11As shown, there are two pole groups 7, each corresponding to an insulating film 4. Each pole group 7 has a tab 74, with a stepped protrusion flush with one of the first side faces 704, and a gap between the tab and the other first side face 704 in the width direction of the cover body 1. The first side faces 704 of the two pole groups 7 are abutted together, such that the two stepped protrusions opposite each other in the width direction abut together to form a stepped convex hull. The stepped convex hull is received within a stepped recess and is positioned within the first recess 301.

[0080] Specifically, the integrated boss has a gap between itself and the edge of the cover plate body 1 in the width direction. After the two pole groups 7 are attached, their first end faces 703 are flush to form a connecting end face, and the stepped protrusions of the two pole groups 7 are attached to form a stepped protrusion protruding on the connecting end face. This stepped protrusion has a gap between itself and the edge of the pole group 7 in the width direction of the cover plate body 1 so as to match the integrated boss.

[0081] In the width direction of the cover plate body 1, the first protrusions 701 of the two pole groups 7 are joined to form a first convex 71, and the second protrusions 702 of the two pole groups 7 are joined to form a second convex 72. The first convex 71 and the second convex 72 are connected in the length direction of the cover plate body 1 to form a stepped convex 72. See [link / reference] Figure 6 The first convex bulge 71 is housed within the first sink trough 301 and is positioned within the first sink trough 301. The second convex bulge 72 is housed within the third sink trough 303.

[0082] During the cell assembly process, after the two pole groups 7 are wrapped with insulating film 4, the tabs 74 of the two pole groups 7 are welded to the pole post 2 of the cell cover plate. Then, the first side 704 of the two pole groups 7 are attached together. The assembly of the two pole groups 7, insulating film 4 and cell cover plate is then installed into the cell housing 6. Finally, the cover plate body 1 is welded to the cell housing 6 to form the cell.

[0083] During the cell assembly process, when assembling the assembled cell cover plate with the electrode group 7, the first recess 301 and the first protrusion 71 provide a limiting fit, which serves to position the two components during assembly. When the cell is subjected to external impact, the first recess 301 can also prevent the electrode group 7 from shifting within the casing and damaging the electrode tabs 74.

[0084] It should be noted that when there is only one pole group 7, the stepped protrusion of a single pole group 7 forms the stepped protrusion that is matched with the first sink 301.

[0085] like Figure 9 and Figure 10As shown, some embodiments of the present invention provide a cell cover plate that further includes a connecting piece 5. The connecting piece 5 is located within a recess. The connecting piece 5 includes a base portion 52, a connecting portion 53, and a welding portion 51 connected in sequence. The base portion 52 is located within a third recess 303 and connected to the electrode post 2, while the welding portion 51 is located within a second recess 302 opposite to and connected to the electrode tab 74. The connecting piece 5 being located within a recess further improves the space utilization rate inside the cell housing 6, which is beneficial for increasing the cell capacity.

[0086] The tabs 74 of the two electrode groups 7 are arranged opposite each other in the width direction of the cover plate body 1, and the two opposite tabs 74 can be connected to the same connecting piece 5. In this way, the tabs 74 of the two electrode groups 7 can be welded to different areas of the same pole post 2, reducing the thickness of the tabs 74 of a single electrode group 7, which can reduce the heat of welding in a single area and improve the welding yield of the electrode group 7 and the pole post 2.

[0087] like Figures 7-9 As shown, the cell cover also includes an insulating member 3. The insulating member 3 is disposed on the side of the cover body 1 near the electrode group 7, and the electrode post 2 passes through the insulating member 3. On the side of the cover body 1 near the electrode group 7, grooves are formed at positions corresponding to the first support platform 11, the mounting platform 13, and the second support platform 12. The insulating member 3 engages with the grooves, and on the side of the insulating member 3 away from the cover body 1, a first recessed groove 301, a second recessed groove 302, and a third recessed groove 303 are formed at positions corresponding to the first support platform 11, the mounting platform 13, and the second support platform 12, respectively.

[0088] When the cell cover is installed on the cell housing 6, the insulating component 3 is located between the cover body 1 and the electrode group 7, serving as insulation between the cover body 1 and the electrode group 7. The electrode post 2 passes through both the cover body 1 and the insulating component 3, with one end of the electrode post 2 located on the side of the insulating component 3 away from the cover body 1, for connection with the electrode tab 74 of the electrode group 7.

[0089] Specifically, see Figure 8 A first groove 101 is formed on the side of the cover plate body 1 near the pole group 7, corresponding to the position of the first support platform 11; a second groove 102 is formed corresponding to the position of the second support platform 12; and a third groove 103 is formed corresponding to the position of the mounting platform 13. The first groove 101, the second groove 102, and the third groove 103 are connected to form an integral groove. A protrusion is formed on the side of the insulating member 3 near the cover plate body 1. The protrusion is located in the integral groove, and the integral recess is formed on the side of the insulating member 3 away from the cover plate body 1, corresponding to the position of the protrusion. This includes a first recess 301 corresponding to the first groove 101, a second recess 302 corresponding to the second groove 102, and a third recess 303 corresponding to the third groove 103.

[0090] Furthermore, the protrusions and integrated grooves are designed to match the shape of the grooves in the cover plate body 1 and the protrusions in the insulating member 3, thus making greater use of the internal space of the protrusions.

[0091] See Figure 10 and Figure 12 An integral boss protrudes from the reference surface of the cover plate body 1. The angle between the side wall of the integral boss and the reference surface is 90°+β. The angle between the side of the first protrusion 71 and the first end face 703 is 90°+θ, 15°≤β≤25°, 15°≤θ≤25°, and -3≤θ-β≤3°.

[0092] The integrated boss has a top wall and multiple side walls connected to the top wall, each side wall having an angle of 90°+β with the reference plane. Multiple sides of the first boss 71 correspond one-to-one with the multiple side walls of the integrated boss, each side having an angle of 90°+θ with the first end face 703. Considering manufacturing errors, setting 15°≤θ≤25° and -3≤θ-β≤3° helps ensure interference-free assembly between the first boss 71 and the cell cover plate.

[0093] The angle between the side surfaces of the first convex hull 71 and the second convex hull 72 and the first end face 703 is 90° + θ. (See also...) Figure 3 The first raised portion 4121 and the second raised portion 4122 each have a top wall and multiple oblique sidewalls connected to the top wall. The second membrane body 412 includes a membrane body, and the first raised portion 4121 and the second raised portion 4122 protrude from the membrane body. The angle between the oblique sidewalls of the first raised portion 4121 and the second raised portion 4122 and the membrane body is γ+90°.

[0094] The membrane body is attached to the first end face 703 of the electrode assembly 7. The top wall of the first raised portion 4121 is attached to the top surface of the first convex shroud 71, and the oblique side wall is attached to the side surface of the first convex shroud 71. The top wall of the second raised portion 4122 is attached to the top surface of the second convex shroud 72, and the oblique side wall is attached to the side surface of the second convex shroud 72. Optionally, 3°≤θ-γ≤8°. If θ-γ is too small, the cell cover 2 will easily interfere with the first raised portion 4121 when assembling with the electrode assembly 73; if θ-γ is too large, the first raised portion 4121 will not easily fit with the convex shroud 32.

[0095] like Figure 13As shown in the illustration, as a specific example, the stepped protrusion is flush with one of the first side faces 704 in the width direction of the cover plate body 1, and the distance between it and the other first side face 704 is b, where 7mm ≤ b ≤ 15mm. The distance between the stepped protrusion and the first side face 704 is related to the distance between the integral boss and the edge of the cover plate body 1. If the value of b is too small, the distance between the integral boss and the edge of the cover plate body 1 will be too small, affecting the stamping yield, or the integral protrusion may easily interfere with the integral recess. If the value of b is too large, it will reduce the load-bearing area of ​​the first support platform 11 and the second support platform 12, affecting the structural strength of the integral boss, or causing a waste of recess space and affecting the positioning effect of the pole assembly 7.

[0096] like Figure 13 As shown, in this embodiment of the invention, the electrode tab 74 has a root section 741 and a closing section 742. The root section 741 is connected to the first end face 703, and the closing section 742 is connected to the end of the root section 741 away from the first end face 703. The position where the root section 741 and the closing section 742 are connected is the closing position of the electrode tab 74. The distance between the first side surface 704 of the electrode group 7 on one side of the cover plate body 1 in the width direction and the closing position is a, where 1mm ≤ a ≤ 3mm. When there are two electrode groups 7, the distance between the closing position and the edge of the two electrode groups 7 that is far away from each other is a.

[0097] In this assembly, the conductive portions extending from each electrode sheet of the electrode group 7 are stacked to form tabs 74. After the cell cover and electrode group 7 are assembled, the tabs 74 bend and close between the cell cover and the electrode group body from their closed position. If the value of a is too small, the tabs 74 may extend beyond the edge of the electrode group 7 after bending and closing, and may be easily scratched by the cell housing 6 when the electrode group 7 is inserted into the housing. If the value of a is too large, the closed section 742 may easily spread out, making it difficult for the tabs 74 to bend and close.

[0098] See Figure 14 In some embodiments, in the width direction of the cover plate body 1, one side of the through hole 4123 is flush with the outer edge of the pole group 7, and the distance between the other side of the through hole 4123 and the retracted position of the pole tab 74 is c, where 1.5mm≤c≤4mm. Since the height of the root segment 741 near the retracted position is higher than that of other positions, by setting 1.5mm≤a≤4mm, assembly interference between the insulating film 4 and the root segment 741 can be avoided.

[0099] Optionally, along the length of the cover plate body 1, the distance between the tab 74 and the through hole 4123 is G1, where 2 ≤ G1 ≤ 4 mm. See details... Figure 3 and Figure 12The dimension of the tab 74 along the length of the cover plate body 1 is W1, and the dimension of the through hole 4123 along the length of the cover plate body 1 is W2, where G1 = (W2 - W1) / 2. Given a fixed width of the tab 74, if the value of G1 is too small, the tab 74 may easily interfere with the insulating film 4 when passing through the through hole 4123; if the value of G1 is too large, it will increase the space it occupies along the length of the cover plate body 1, which is not conducive to the dimensional setting of the stepped protrusion.

[0100] Design of Experiments (DOE) was conducted to test certain parameter ranges defined in the embodiments of this invention. During the production of the insulating film, damage during the stamping process was detected. During the electrode group coating and cell assembly processes, structural interference was detected. The experimental results are shown in Table 1, where T1, T2, H1, H2, W1, W2, a, and G1 are in mm.

[0101] Table 1: Experimental Data 1

[0102] 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 for wrapping the outer side of the electrode assembly of 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 has stepped protrusions and through holes spaced apart in a second direction. The stepped protrusions are adapted to cover the stepped protrusions on the end face of the electrode assembly, and the through holes are adapted to allow the tabs of the electrode assembly to pass through. The first direction and the second direction are perpendicular. The second membrane group is connected to the first membrane group at both ends in the second direction. The second membrane group includes a first folded body, a second folded body and a third folded body distributed along the first direction. The first folded body is connected to the first membrane body, the second folded body is connected to the second membrane body, and the third folded 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.

2. The insulating film according to claim 1, characterized in that, The first membrane includes a first wrapping portion and a second wrapping portion connected together, the first wrapping portion being connected to the second membrane; the third membrane includes a third wrapping portion and a fourth wrapping portion connected together, 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 the overlapping portion is opposite to the second film.

3. The insulating film according to claim 2, characterized in that, The second package includes a fourth folding body and a fifth folding body connected in the first direction. The fourth folding body is connected to the first package. The fifth folding body is foldable relative to the fourth folding body, so that the fifth folding body is connected to the third package and opposite to the first package.

4. The insulating film according to claim 3, characterized in that, The inner surface of the fifth folding body is provided with an adhesive layer, and the fifth folding body can be bonded to the third wrapping part through the adhesive layer; And / or, the extension length of the fifth folding body relative to the fourth folding body in the first direction is h, where 10mm ≤ h ≤ 20mm.

5. The insulating film according to claim 1, characterized in that, The stepped raised portion includes a first raised portion and a second raised portion connected sequentially in the second direction, wherein the raised height of the first raised portion is greater than the raised height of the second raised portion; Wherein, the wall thickness of the top wall of the first raised portion and the second raised portion is T1, the wall thickness of other areas is T2, the raised height of the first raised portion is H1, the raised height of the second raised portion is H2, 0.25mm≤T1≤0.35mm, 0.08mm≤T2≤0.15mm, H1 / T1≤20, H2 / T1≤8; and / or, the top wall of the first raised portion is provided with an inlet for the electrolyte to pass through.

6. A battery cell, characterized in that, include: The battery cell casing has an opening; A battery cell cover plate includes a cover plate body, the cover plate body being disposed at the opening and surrounding the battery cell housing to form a receiving cavity, the cover plate body having a protrusion on the side away from the receiving cavity, and the battery cell cover plate having a stepped groove on the side facing the receiving cavity corresponding to the position of the protrusion; An electrode assembly is disposed within the receiving cavity and has a first end face and a second end face facing away from each other, as well as 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. A stepped protrusion is provided on the first end face. The electrode lug of the electrode assembly is connected to the first end face, and the stepped protrusion is received in the stepped groove. The insulating film as described in any one of claims 1 to 5 is located between the electrode group and the cell housing. The second film body wraps around the first end face. The first film body and the third film body respectively wrap around the two first side faces and the second end face. The two second film groups are folded relative to the first film group and wrapped around the two second side faces one by one. The stepped protrusion covers the stepped convex portion. The electrode tab passes through the through hole.

7. The battery cell according to claim 6, characterized in that, The cell cover plate also includes a pole post. The boss includes a first support platform, a mounting platform and a second support platform arranged along the length direction of the cover plate body. The mounting platform is connected between the first support platform and the second support platform. The pole post passes through the cover plate body and protrudes from the mounting platform. The pole post is connected to the electrode tab. The side of the cell cover plate facing the receiving cavity has a first recess, a third recess and a second recess respectively formed at the positions of the first support platform, the mounting platform and the second support platform. The first recess and the third recess are connected to form the stepped recess. The second recess is connected to the third recess. The stepped protrusion includes a first protrusion and a second protrusion connected in the length direction. The first protrusion is received in the first sinker, the second protrusion is received in the third sinker, and the electrode tab is received in the second sinker.

8. The battery cell according to claim 7, characterized in that, The number of electrode groups is two, each electrode group corresponds to one insulating film, the electrode group has the electrode tab, the stepped protrusion is flush with one of the first side surfaces and has a gap with the other first side surface, one first side surface of the two electrode groups is attached to each other, such that two stepped protrusions opposite each other in the width direction of the cover plate body are attached to form a stepped protrusion, the stepped protrusion is received in the stepped groove and is limited and matched with the first groove.

9. The battery cell according to claim 7, characterized in that, There are two mounting platforms and two second support platforms. The first support platform is located between the two second support platforms, and the two mounting platforms are respectively located on both sides of the first support platform. Each mounting platform is provided with the pole post.

10. The battery cell according to claim 7, characterized in that, The cell cover plate also includes an insulating component, which is disposed on the side of the cover plate body near the electrode group. The electrode post passes through the insulating component. The side of the cover plate body near the electrode group forms a groove corresponding to the positions of the first support platform, the mounting platform and the second support platform. The insulating component engages with the groove, and the side of the insulating component away from the cover plate body forms the first recess, the second recess, and the third recess respectively, corresponding to the positions of the first support platform, the mounting platform, and the second support platform.

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