Battery cell and preparation method thereof

Abstract

The present application relates to a battery cell and a preparation method thereof. The battery cell includes an end cover, an electrode assembly, an insulating filler and a thermally conductive adhesive. The end cover includes a cover plate and a pole arranged on the cover plate. The electrode assembly has a pole ear end arranged facing the cover plate, and a pole ear is protruding from the pole ear end. The insulating filler is arranged between the electrode assembly and the cover plate. It has a filling space and an avoidance hole connected to the filling space. The end of the insulating filler facing the pole ear end is provided with an opening. The pole ear extends into the filling space through the opening. The pole column is provided with an avoidance hole and is connected to the pole ear in the filling space. The thermally conductive adhesive is filled in the filling space through the opening and covers the pole ear and the pole column. The technical solution of the present application improves the heat dissipation capacity of the battery cell and enhances the reliability of the battery cell.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to battery cells and methods for preparing the same. Background Art

[0002] As the charge rate of battery cells increases, the internal temperature of the battery cells increases during the charging process. The main source of high temperatures in the battery cells is the electrode assembly within them. The high temperature of the electrode assembly can be transferred through the tabs to the terminal, where it then exchanges heat with the external liquid cooling structure. If the connection between the terminal and the tab is not secure, it will affect the heat dissipation of the electrode assembly and reduce the reliability of the battery cells. Summary of the Invention

[0003] Based on this, a battery cell and a preparation method thereof are provided, which can improve the heat dissipation capability of the battery cell and enhance its reliability.

[0004] In a first aspect, the present application provides a battery cell, comprising:

[0005] An end cover, comprising a cover plate and a pole arranged on the cover plate;

[0006] The electrode assembly has a tab end facing the cover plate, and the tab end is provided with a tab protruding therefrom;

[0007] an insulating filler, disposed between the electrode assembly and the cover plate, having a filler space and a relief hole communicating with the filler space; an opening is provided at one end of the insulating filler facing the tab, the tab extends into the filler space through the opening, the pole passes through the relief hole, and is connected to the tab within the filler space; and

[0008] The thermal conductive adhesive is filled into the adhesive filling space through the opening and covers the tab and the pole.

[0009] In some embodiments, a projection of the opening along the thickness direction of the cover plate includes a projection of the tab end along the thickness direction.

[0010] In some embodiments, the pole includes a matching section, and the matching section is matched with the avoidance hole itself or through a sealing member.

[0011] In some embodiments, the pole includes the matching section and a welding section adjacent to the matching section, the welding section is located in the glue-filled space and welded to the tab; along the thickness direction of the cover plate, the projection of the welding section exceeds the projection of the matching section and the projection of the avoidance hole;

[0012] The inner wall of the avoidance hole is configured to be deformable.

[0013] In some embodiments, a plurality of notches are formed on the hole wall of the avoidance hole, and the plurality of notches are arranged at intervals along the circumference of the avoidance hole;

[0014] Each of the notches passes through the wall of the insulating filler along the thickness direction, so that the inner wall of the avoidance hole can be bent and deformed.

[0015] In some embodiments, the insulating filler comprises a separator bar and / or a boss;

[0016] The separator is located in the glue-filled space and divides the glue-filled space into a main space and a glue overflow space. The avoidance hole is connected to the main space, and the tab extends into the main space. The separator forms a glue overflow channel connecting the glue overflow space with the main space. At least the main space is filled with the thermally conductive glue.

[0017] A liquid injection hole is provided on the cover plate, the convex column is located in the glue-filled space, extends toward the pole ear end to pass through the opening, and is spaced apart from the pole ear end; a liquid injection channel connected to the liquid injection hole is formed in the convex column; along the thickness direction of the cover plate, the projection of the outlet end of the liquid injection hole is located within the projection range of the inlet end of the liquid injection channel.

[0018] In some embodiments, the battery cell further includes an insulating support member, which is disposed at the terminal end of the tab and is disposed opposite to the thermally conductive adhesive;

[0019] The insulating support is provided with a hollow portion which is provided through the thickness direction of the cover plate, and the hollow portion is sleeved on the periphery of the pole ear.

[0020] In some embodiments, the cover plate has an outer end surface set away from the electrode assembly; each of the poles has a first flow-through surface set away from the electrode assembly, and the area S1 of the first flow-through surface of all the poles and the area S2 of the outer end surface satisfy: 0.45S2≤S1<S2.

[0021] In some embodiments, each of the poles has a second flow surface disposed opposite to the first flow surface, and the area S1' of the second flow surface of all the poles and the area S2 of the outer end surface satisfy: 0.5S2≤S1'<S2.

[0022] In some embodiments, the end cover includes N poles, and the N poles are arranged side by side and spaced apart along the length direction of the cover plate, where N is greater than or equal to 4 and is an even number.

[0023] In some embodiments, within the plane where the outer end surface is located, the interval between the first flow surfaces of adjacent poles is m, the distance between the first flow surfaces of the first and last poles and the edge of the outer end surface in the length direction is p, and the distance between the first flow surfaces of all poles and the edge of the outer end surface in the width direction is n;

[0024] Satisfies: S2=(a+2n)*[N*b+2p+(N-1)*m], where m≥2mm, n≥4mm, p≥4mm.

[0025] In some embodiments, there are a plurality of tabs, which are spaced apart along the length direction of the cover plate. Each pole is welded to a corresponding tab, and the polarities of adjacent tabs are opposite.

[0026] In some embodiments, in the length direction of the cover plate, the length L1 of the negative electrode tab and the length L2 of the positive electrode tab satisfy:

[0027] L1≤L2, or, 0.25L2≤L1≤0.9L2.

[0028] In a second aspect, the present application provides a method for preparing a battery cell, which is applied to the battery cell described in any of the above embodiments. The method comprises:

[0029] Pass the pole on the end cover through the avoidance hole of the insulating filler so that the pole extends into the filling space of the insulating filler;

[0030] The opening of the insulating filler is facing upwards, and the tab of the electrode assembly in a flat state is welded to the electrode post located in the filler space; when in the flat state, the tab end of the electrode assembly is located on one side of the electrode assembly in the horizontal direction;

[0031] pouring thermal conductive glue into the glue filling space through the opening;

[0032] The electrode tab is bent and the electrode assembly is turned over until the end of the electrode tab of the electrode assembly is arranged opposite to the opening of the insulating filler.

[0033] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0034] In the above-mentioned battery cell, an insulating filler is provided between the cover plate of the end cap and the tab end of the electrode assembly. The pole and the tab both extend into the filler space within the insulating filler. During the preparation of the battery cell, the thermally conductive glue is poured into the filler space through the opening of the insulating filler, ensuring that the thermally conductive glue effectively covers the pole and the tab, enhancing the connection reliability between the two, and also increasing the heat transfer area between the two to a certain extent, thereby improving the heat transfer efficiency of the two. Moreover, by using the filler space to limit the amount of thermally conductive glue used, the consumption of thermally conductive glue can be reduced, thereby reducing costs. In summary, the heat dissipation capacity of the battery cell proposed in this application is improved, and its reliability is also improved.

[0035] In the battery cell manufacturing method described above, the insulating filler is inverted with its opening facing upward. When the electrode assembly is placed flat, the tab is inserted through the opening into the filler space and welded to the terminal post within the filler space. This simplifies and facilitates the welding of the tab and post. Furthermore, after the tab and post are welded, thermally conductive adhesive can be poured through the opening, ensuring effective coverage of the tab and post, and making the pouring process easier to control. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0037] Figure 1 Schematic diagrams showing the appearance of battery cells according to some embodiments.

[0038] Figure 2 Shown Figure 1 Exploded diagram of a battery cell shown.

[0039] Figure 3 Shown Figure 1 Schematic diagram of the internal structure of a battery cell.

[0040] Figure 4 Schematic diagrams of the structures of insulating fillers according to some embodiments are shown.

[0041] Figure 5 Shown Figure 3 Enlarged view of point I in the middle.

[0042] Figure 6 An exploded schematic view of an end cap according to some embodiments is shown.

[0043] Figure 7 An internal cross-sectional view of a seal according to some embodiments is shown.

[0044] Figure 8Shown Figure 4 Another orientation view of the insulating filler is shown.

[0045] Figure 9 Shown Figure 8 Enlarged view of point II in the middle.

[0046] Figure 10 Schematic diagrams of partial structures of cover plates of some embodiments are shown.

[0047] Figure 11 Schematic diagrams of the structures of sealing pins according to some embodiments are shown.

[0048] Figure 12 Schematic diagrams of partial structures of insulating fillers in some embodiments are shown.

[0049] Figure 13 Shown Figure 2 Enlarged schematic diagram of point III in the middle.

[0050] Figure 14 Schematic diagrams of the structures of insulating supports of some embodiments are shown.

[0051] Figure 15 Shown Figure 14 Another orientation view of the insulating support is shown.

[0052] Figure 16 A partial structural schematic diagram of a battery cell according to some embodiments is shown.

[0053] Figure 17 An exploded schematic diagram of a battery cell according to some embodiments is shown.

[0054] Figure 18 Shown Figure 17 Another orientation view of the battery cell is shown.

[0055] Figure 19 Schematic diagrams of the structures of end caps of some embodiments are shown.

[0056] Figure 20 Schematic cross-sectional views of end caps according to some embodiments are shown.

[0057] Figure 21 A schematic flow chart showing a method for preparing a battery cell according to some embodiments is shown.

[0058] Figure 22 A schematic diagram showing the state changes of the electrode assembly during the preparation process of the battery cell is shown.

[0059] The accompanying drawings in the specific implementation manner are as follows:

[0060] 100, battery cell; Z, thickness direction; X, length direction; Y, width direction; 10, end cap; 11, cover plate; 11a, injection hole; a1, sink; a2, through hole; 11b, pole hole; 12, pole; 12b, matching section; 12c, welding section; GL1, first flow surface; GL2, second flow surface; 13, seal; 13d, mounting hole; 13e, first sealing groove; 13i, second sealing groove; 14, sealing pin; 14g, boss; 14k, column; W, outer end surface; T, spacer; 20, electrode assembly; J, tab end; 21, tab; 21a, root section ; 21b, tail section; 21c, bending section; 30, insulating glue filling part; 31, bottom plate; 32, side panel; 30h, glue filling space; h1, main space; h2, glue overflow space; 30i, avoidance hole; 30m, opening; 30n, notch; 30p, corner position; 33, dividing strip; 33q, glue overflow channel; 34, convex column; 34r, liquid injection channel; 40, thermal conductive adhesive; 50, insulating support part; 50u, hollow position; u1, support groove; u11, opening; d1, first end face; d2, second end face; 51, reinforcing rib; 50v, liquid hole; 60, shell; 70, thermal conductive covering part. DETAILED DESCRIPTION

[0061] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0062] In the description of the present application, it should be understood that, if any, terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0063] Furthermore, if used, the terms "first" and "second," if present, are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0064] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connected," and "fixed" should be interpreted broadly. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components, unless otherwise expressly limited. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0065] To improve the heat dissipation of the electrode assembly, the applicant is considering placing thermally conductive adhesive between the end caps of the battery cell and the electrode assembly. This allows the adhesive to cover the poles and tabs, improving the reliability of the connection between the two. It also allows the adhesive to increase the heat transfer path, improve the heat dissipation effect, and reduce the temperature difference in the height direction of the battery cell. When considering the placement of the thermally conductive adhesive, if a dispensing method (such as applying the thermally conductive adhesive directly to the connection between the poles and tabs, or applying the thermally conductive adhesive to the inside of the end cap) is used to cover the connection between the tabs and the poles, the efficiency is not only low, but also prone to uneven distribution of the thermally conductive adhesive. If a glue injection hole is provided on the end cap and glue is injected into the battery cell through the glue injection hole, a large amount of thermally conductive adhesive needs to be filled to fill the space between the end cap and the electrode assembly, ensuring that the thermally conductive adhesive can effectively cover the connection between the poles and tabs, which is costly.

[0066] Based on this, an embodiment of the present application proposes a battery cell and a preparation method thereof, by configuring an insulating filler between the end cover and the electrode assembly, and using the filling space of the insulating filler to limit the amount of thermal conductive adhesive. During the preparation of the battery cell, the thermal conductive adhesive is injected into the filling space through the opening of the insulating filler. While reducing the amount of thermal conductive adhesive, it is ensured that the thermal conductive adhesive can well cover the pole and the ear, thereby improving the heat dissipation capacity of the battery cell and thereby improving the reliability of the battery cell.

[0067] The battery cells in the embodiments of the present application are described in detail below.

[0068] Figure 1 Schematic diagrams of the appearance of a battery cell 100 according to some embodiments are shown. Figure 2 Shown Figure 1 An exploded schematic diagram of a battery cell 100 is shown. Figure 3 Shown Figure 1 Schematic diagram of the internal structure of the battery cell 100 is shown.

[0069] Please combine Figures 1 to 3 The battery cell 100 proposed in the embodiment of the present application includes an end cap 10, an electrode assembly 20, an insulating filler 30, and a thermally conductive adhesive 40. The end cap 10 includes a cover plate 11 and a pole post 12 provided on the cover plate 11. The electrode assembly 20 has a tab end J facing the cover plate 11, and a tab 21 is protruding from the tab end J. The insulating filler 30 is provided between the electrode assembly 20 and the cover plate 11. It has a filling space 30h and an avoidance hole 30i connected to the filling space 30h. The insulating filler 30 has an opening 30m at one end facing the tab end J. The tab 21 extends into the filling space 30h through the opening 30m. The pole post 12 is provided with the avoidance hole 30i and is connected to the tab 21 in the filling space 30h. The thermally conductive adhesive 40 is filled into the filling space 30h through the opening 30m and covers the tab 21 and the pole post 12.

[0070] Specifically, the cover plate 11 of the end cap 10 covers the open end of the outer shell 60. The tab end J is located at one or both ends of the electrode assembly 20. When the tab end J is located at one end of the electrode assembly 20, it is typically provided with a positive tab and a negative tab protruding therefrom. Accordingly, the cover plate 11 covers one open end of the outer shell 60. When the tab end J is located at opposite ends of the electrode assembly 20, at least one tab 21 protruding therefrom is provided. Accordingly, the cover plate 11 covers both open ends of the outer shell 60. It is possible, but not limited to, that the battery cell 100 is a prismatic battery and the cover plate 11 is a square plate.

[0071] Typically, the cover plate 11 is provided with a post hole 11b. The post 12 passes through the post hole 11b. One end of the post 12 extends outside the cover plate 11 to be directly or indirectly electrically connected to an external circuit, and the other end of the post 12 extends inside the cover plate 11 (the side facing the electrode assembly 20) to be connected to the tab 21. The connection between the post 12 and the tab 21 includes welding, clamping, etc.

[0072] The insulating filler 30 is arranged between the tab end J and the cover plate 11 to insulate the tab end J from the cover plate 11 and reduce the risk of electrical leakage from the cover plate 11. The insulating filler 30 forms a filler space 30h. An opening 30m is provided on the end facing the tab end J. The opening 30m is an open hole / opening structure that connects the filler space 30h with the tab end J.

[0073] One end of the pole 12 is provided with a clearance hole 30i extending into the glue filling space 30h. The pole tab 21 is provided with an opening 30m extending into the glue filling space 30h. The two are connected within the glue filling space 30h, with the connection between the two located within the glue filling space 30h. The insulating glue filling 30 and the cover plate 11 can be assembled, bonded, or otherwise secured in position. Of course, other methods can be used to secure the insulating glue filling 30.

[0074] Figure 4 The schematic diagram of the structure of the insulating filler 30 of some embodiments is shown. Figure 4 The insulating filler 30 can be formed from a base plate 31 and side plates 32. The side plates 32 are arranged in a circle around the edge of the base plate 31, and together they form a filler space 30h. The end of the side plate 32 facing away from the base plate 31 is completely open to form the aforementioned opening 30m. The base plate 31 is positioned adjacent to the cover plate 11, and the avoidance hole 30i is located on the base plate 31. In this case, the insulating filler 30 has a simple structure, which can reduce manufacturing costs. The shape of the base plate 31 can generally match that of the cover plate 11. For example, if the cover plate 11 is a square plate, the base plate 31 can also be a square plate.

[0075] In other embodiments, the insulating filler 30 may further include a sealing plate (not shown), disposed at the end of the side plate 32 facing away from the bottom plate 31 and opposite the bottom plate 31. The sealing plate is provided with an opening facing the tab end J, which serves as the aforementioned opening 30m. In this case, one or more openings may be provided in the sealing plate, each of which may extend through one or more tabs 21 and into the filler space 30h.

[0076] Specifically, the number of insulating fillers 30 can be configured as one or more. If multiple insulating fillers 30 are configured, different tabs 21 and different poles 12 can be inserted into the filling space of each insulating filler 30, that is, one set of tabs 21 and poles 12 is correspondingly configured with one insulating filler 30. Figure 2 and Figure 3 As shown, only one insulating filler 30 is provided, and all the tabs 21 and all the poles 12 are located in the filling space 30 h of the insulating filler 30 , thereby simplifying the structure of the battery cell 100 .

[0077] During the preparation of the battery cell 100, after the insulating filler 30 is secured (with its opening 30m facing away from the cover plate 11), the tab 21 and the terminal post 12 are secured within the filler space 30h (e.g., by welding or clamping). Then, flowing thermally conductive adhesive 40 is injected into the filler space 30h through the opening 30m and allowed to solidify. It should be noted that the thermally conductive adhesive 40 can completely fill the filler space 30h and be in thermal contact with the tab end J of the electrode assembly 20. Alternatively, the thermally conductive adhesive 40 can only partially fill the filler space 30h, as long as it effectively covers the tab 21 and the terminal post 12.

[0078] In the battery cell 100 described above, an insulating filler 30 is provided between the cover plate 11 of the end cap 10 and the tab end J of the electrode assembly 20. The pole 12 and the tab 21 both extend into the filler space 30h within the insulating filler 30. During the preparation process of the battery cell 100, the thermally conductive adhesive 40 is poured into the filler space 30h through the opening 30m of the insulating filler 30, ensuring that the thermally conductive adhesive 40 effectively covers the pole 12 and the tab 21, enhancing the connection reliability between the two, and also increasing the heat transfer area between the two to a certain extent, improving the heat transfer efficiency between the two, thereby reducing the temperature difference between the two. Moreover, by using the filler space 30h to limit the amount of thermally conductive adhesive 40, the consumption of thermally conductive adhesive 40 can be reduced, thereby reducing costs. Compared with the prior art, the heat dissipation capacity of the battery cell 100 proposed in this application is improved, and its reliability is improved.

[0079] Typically, but not exclusively, the insulating filler 30 is thermally connected to the cover plate 11. Specifically, the insulating filler 30 can be directly bonded to the inner side of the cover plate 11 or adhesively bonded. In this case, the insulating filler 30 is configured to conduct heat between the cover plate 11 and the tab 21 and the post 12. Heat is transferred from the tab 21 and the post 12 to the cover plate 11 through the thermally conductive adhesive 40 and the insulating filler 30. Heat is then exchanged between the cover plate 11 and the external liquid cooling structure, thereby improving the heat dissipation capability of the battery cell 100.

[0080] To facilitate the injection of the thermally conductive adhesive 40, in some embodiments, during the injection of the thermally conductive adhesive 40, the end of the insulating filler 30 where the opening 30m is located is aligned with and spaced from the tab end J. After the battery cell 100 is assembled, whether the end where the opening 30m is located is spaced from the tab end J is not specified. For example, before the tab 21 is bent, it extends into the filler space 30h, at which point the opening 30m is spaced from the tab end J. After the injection of the thermally conductive adhesive 40 is completed, the tab 21 is bent so that the tab end J and the opening 30m are aligned until the tab end J closes the opening 30m.

[0081] In some embodiments, combined Figure 3 It is understood that the projection of the opening 30 m along the thickness direction Z of the cover plate 11 includes the projection of the tab end J along the thickness direction Z.

[0082] At this time, the open area of ​​the opening 30m is relatively large. When the tab 21 and the pole 12 are welded, the welding operation of the pole 12 and the tab 21 is facilitated within the glue filling space 30h. It also allows visualization of the glue filling process, ensuring that the thermally conductive glue 40 effectively covers the pole 12 and the tab 21. Specifically, the projection of the opening 30m can exceed the projection range of the tab end J. Specifically, the opening 30m can be formed by the end of the side plate 32 facing away from the bottom plate 31.

[0083] Figure 5 Shown Figure 3 Enlarged view of point I in the middle.

[0084] In some embodiments, combined Figure 5 It is understood that the pole 12 includes a matching section 12 b , and the matching section 12 b is matched with the avoidance hole 30 i by itself or through the sealing member 13 .

[0085] In one example (not shown), the coupling section 12b itself is coupled with the avoidance hole 30i, for example, a coupling groove is provided on one of the two, and a coupling protrusion is provided on the other to be locked in the coupling groove. Figure 5 In the illustrated example, the mating section 12 b of the pole 12 is mated with the avoidance hole 30 i via the sealing member 13 .

[0086] At this time, since the mating section 12b is directly or indirectly mated with the avoidance hole 30i, the positional relationship between the two is fixed. Thus, through the cooperation between the mating section 12b of the pole 12 and the avoidance hole 30i, the position of the insulating filler 30 and the cover plate 11 can be fixed, thereby achieving the installation of the insulating filler 30.

[0087] When the mating section 12b mates with the avoidance hole 30i, the insulating filler 30 can be positioned and installed by mating the mating section 12b and the avoidance hole 30i. Positioning and installation of the insulating filler 30 is independent of the cover plate 11, and therefore whether the insulating filler 30 is thermally connected to the cover plate 11 is not a limitation. Of course, regardless of whether the mating section 12b mates with the avoidance hole 30i, the insulating filler 30 can also be installed by bonding, snapping, or fastening the cover plate 11.

[0088] Figure 6 An exploded schematic view of the end cap 10 is shown in accordance with some embodiments. Figure 7 An internal cross-sectional view of the seal 13 is shown for some embodiments.

[0089] In a specific embodiment, combining Figure 5 、 Figure 6 and Figure 7It is understood that the cover plate 11 includes a pole hole 11b, and the seal 13 is installed in the pole hole 11b. The seal 13 is provided with a first sealing groove 13e that is concave-convexly matched with the hole wall of the pole hole 11b. The seal 13 has a mounting hole 13d, and the matching section 12b passes through the mounting hole 13d. A second sealing groove 13i is formed on the hole wall of the mounting hole 13d that is concave-convexly matched with the matching section 12b.

[0090] The seal 13 can be made of a soft material such as silicone or rubber. The seal 13 is annular, such as a circular or square ring. The inner wall of the seal 13 encloses a mounting hole 13d, which is provided through the cover 11 in the thickness direction Z. The seal 13 penetrates the pole hole 11b and is sealed with the concave-convex structure on the wall of the pole hole 11b via a first sealing groove 13e. The mounting hole 13d of the seal 13 is penetrated by the mating section 12b of the pole 12, and the concave-convex structure on its outer wall is sealed with the second sealing groove 13i.

[0091] At this time, the pole 12 and the pole hole 11b of the cover plate 11 are sealed and connected via the concave-convex seal 13. The sealing path is long, which can effectively ensure the sealing performance of the connection between the pole 12 and the cover plate 11 and play an insulating effect.

[0092] Specifically, if Figure 5 As shown, the inner wall of the avoidance hole 30i of the insulating filler 30 can be matched with the hole wall of the pole hole 11b in the first sealing groove 13e.

[0093] In some embodiments, the terminal 12 includes the aforementioned mating section 12b and a welding section 12c adjacent to and connected to the mating section 12b. The welding section 12c is located in the glue-filled space 30h and welded to the terminal tab 21. Along the thickness direction Z of the cover plate 11, the projection of the welding section 12c extends beyond both the projection of the mating section 12b and the projection of the avoidance hole 30i. The inner wall of the avoidance hole 30i is configured to be deformable.

[0094] The projected shapes of the welding section 12c, the mating section 12b, and the avoidance hole 30i generally match. For example, if all three projected shapes are circular, the outer diameter of the welding section 12c is larger than the outer diameter of the mating section 12b, and the inner diameter of the avoidance hole 30i is smaller than the outer diameter of the welding section 12c. For another example, if all three projected shapes are square, the dimensions of the welding section 12c are larger than the dimensions of the mating section 12b and the avoidance hole 30i in both the length direction (X) and the width direction (Y) of the square projection.

[0095] The inner wall of the avoidance hole 30i is deformable, which means that the avoidance hole 30i can change shape with the action of external force to allow the welding section 12c to pass through the avoidance hole 30i. To achieve the internal deformation of the avoidance hole 30i, the insulating filler 30 can be made of a soft structure, such as silicone or rubber.

[0096] When assembling the battery cell 100, the insulating filler 30 is installed on the inner side of the end cover 10. During this process, as the insulating filler 30 gradually approaches the inner side of the cover plate 11, the avoidance hole 30i is first inserted into the welding section 12c (during this process, the avoidance hole 30i is deformed under the action of the welding section 12c). After the welding section 12c passes through the avoidance hole 30i, the avoidance hole 30i reaches the position where it mates with the mating section 12b (the avoidance hole 30i returns to its initial state).

[0097] At this time, the portion of the insulating filler 30 where the avoidance hole 30 i is located cannot escape from the welding section 12 c of the pole 12 in the thickness direction Z of the cover plate 11 , thereby improving the installation stability of the insulating filler 30 .

[0098] Figure 8 Shown Figure 4 Another orientation view of the insulating filler 30 is shown. Figure 9 Shown Figure 8 Enlarged view of point II in the middle.

[0099] Specifically in the embodiment, refer to Figure 4 、 Figure 8 and Figure 9 The inner wall of the avoidance hole 30i is recessed to form a plurality of notches 30n, which are spaced apart along the circumference of the avoidance hole 30i. Each notch 30n penetrates the wall of the insulating filler 30 along the thickness direction Z, allowing the inner wall of the avoidance hole 30i to bend and deform.

[0100] During assembly of the battery cell 100, as the insulating filler 30 gradually approaches the inside of the cover plate 11, the avoidance hole 30i engages with the welding section 12c. Due to the compression of the welding section 12c, the inner wall portions of the avoidance hole 30i on either side of the notch 30n bend toward the interior of the filler space 30h, enlarging the hole structure formed by the avoidance hole 30i and allowing the welding section 12c to pass through the avoidance hole 30i. Once the welding section 12c passes through the avoidance hole 30i, the compression effect of the welding section 12c disappears, and the bent portion of the insulating filler 30 rebounds to its original state, successfully mating with the mating section 12b.

[0101] At this time, by setting a plurality of notches 30n on the circumference of the avoidance hole 30i, the notches 30n can realize the deformation of the hole wall of the avoidance hole 30i to allow the welding section 12c to pass through. There is no requirement for whether the material of the insulating filler 30 is a flexible material, so that the material selection range of the insulating filler 30 is wider, and the overall strength of the insulating filler 30 can be improved.

[0102] In one embodiment, if Figure 4 and Figure 8As shown, the avoidance hole 30i is a square hole, and the notch 30n is arranged at the corner position 30p of the avoidance hole 30i. In this case, the notch 30n is arranged at the corner position 30p of the avoidance hole 30i, so that the inner wall of the avoidance hole 30i is more likely to bend and deform. At the same time, when returning to the original state after bending and deformation, it can prevent the notch 30n from being unable to deform or the notch 30n from being torn and deformed and unable to recover, which would affect the sealing effect.

[0103] In some embodiments, combined Figure 8 and Figure 9 It is understood that the insulating filler 30 includes a separator 33. The separator 33 is located in the filler space 30h and divides the filler space 30h into a main space h1 and an overflow space h2. The avoidance hole 30i is connected to the main space h1, and the tab 21 extends into the main space h1. The separator 33 forms an overflow channel 33q that connects the overflow space h2 with the main space h1. At least the main space h1 is filled with thermally conductive adhesive 40.

[0104] As can be understood, the pole 12 extends into the main space h1 after being provided with the avoidance hole 30i, thereby connecting with the tab 21 located in the main space h1. When the insulating filler 30 is formed by the base plate 31 and the side plates 32, the separator 33 is disposed on the base plate 31. Specifically, the separator 33 can enclose the filler space 30h to form a glue overflow space h2, or the separator 33 can be separated from the side plates 32 to form a glue overflow space h2.

[0105] The overflow glue channel 33q is used for storing excess thermal conductive glue 40 in the overflow glue space h2 when the required amount of thermal conductive glue 40 in the main space h1 is reached, so as to prevent the thermal conductive glue 40 from overflowing the glue filling space 30h.

[0106] In one embodiment, the glue overflow channel 33q comprises a glue overflow hole formed in the separator bar 33 itself. The height of the glue overflow hole in the thickness direction Z of the cover plate 11 is no less than the thickness of the thermally conductive adhesive 40 required within the main space h1. In another embodiment, the separator bar 33 is positioned below the end surface where the opening 30m is located (i.e., the separator bar 33 is lower than the end of the side panel 32 facing away from the bottom panel 31), thereby forming the glue overflow channel 33q between the separator bar 33 and the end surface where the opening 30m is located. The height of the separator bar 33 determines the thickness of the thermally conductive adhesive 40. This approach can simplify the structure of the separator bar 33.

[0107] During the glue filling process, thermally conductive adhesive 40 is injected into main space h1 through opening 30m until it effectively encapsulates tab 21 and post 12. If the required amount of thermally conductive adhesive 40 is reached in main space h1 and the injection is not stopped promptly, excess thermally conductive adhesive 40 can flow through overflow channel 33q into overflow space h2. This prevents overflow of thermally conductive adhesive 40 from filling space 30h and facilitates determining whether the thermally conductive adhesive 40 has been properly filled, effectively controlling the amount of thermally conductive adhesive 40 used.

[0108] In one embodiment, the separator strip 33 and the sidewall of the glue-filled space 30h (formed by the side plate 32) are separated to form a glue overflow groove, which serves as the glue overflow space h2. In this case, the glue overflow space h2 is located at the edge of the glue-filled space 30h, facilitating the layout of the tabs 21 and the poles 12.

[0109] In some embodiments, combined Figure 3 and Figure 8 It is understood that the insulating filler 30 includes a protrusion 34. A liquid injection hole 11a is provided on the cover plate 11. The protrusion 34 is located in the filler space 30h and extends toward the tab end J, passing through the opening 30m and spaced from the tab end J. A liquid injection channel 34r is formed within the protrusion 34, communicating with the liquid injection hole 11a. Along the thickness direction Z of the cover plate 11, the projection of the outlet end of the liquid injection hole 11a is located within the projection of the inlet end of the liquid injection channel 34r.

[0110] Specifically, the bottom plate 31 is bonded to the cover plate 11. A protruding column 34 is provided on the bottom plate 31 at a position corresponding to the injection hole 11a, projecting toward the tab end J. An injection channel 34r within the protruding column 34 is arranged opposite the injection hole 11a. Electrolyte injected through the injection hole 11a first flows through the injection channel 34r before reaching the tab end J of the electrode assembly 20.

[0111] Because the projection of the outlet of the injection hole 11a lies within the projection of the inlet of the injection channel 34r (i.e., the inner diameter of the inlet of the injection channel 34r is larger than the inner diameter of the outlet of the injection hole 11a), the electrolyte, after exiting the injection hole 11a, smoothly enters the injection channel 34r and does not flow out of the injection channel 34r. Because the protrusion 34 extends beyond the opening by 30m, the thermally conductive adhesive 40 does not clog the injection channel 34r during the glue pouring process. Because the protrusion 34 is spaced from the tab end J, the electrolyte, after exiting the injection channel 34r, can flow toward all areas of the tab end J, ensuring more uniform electrolyte penetration into the electrode assembly 20.

[0112] In this way, the provision of the protrusion 34 allows the electrolyte to be smoothly injected into the battery cell 100 and facilitates the uniform distribution of the electrolyte within the electrode assembly 20 .

[0113] Figure 10 Schematic diagrams of the partial structures of the cover plate 11 of some embodiments are shown. Figure 11 Schematic diagrams of the structures of the sealing pins 14 of some embodiments are shown. Figure 12 Schematic diagrams of partial structures of insulating fillers 30 according to some embodiments are shown.

[0114] In some embodiments, reference Figure 3 The end cap 10 further includes a sealing pin 14 disposed at the injection hole 11a. The sealing pin 14 is sealed at the injection hole 11a to prevent the free electrolyte inside the battery cell 100 from leaking from the injection hole 11a.

[0115] Specifically in the embodiment, combined with Figure 3 、 Figure 10 and Figure 11 It is understood that the injection hole 11a includes adjacent and connected grooves a1 and through-hole a2, and the sealing nail 14 includes a connected boss portion 14g and a column portion 14k. The boss portion 14g is supported on the bottom wall of the groove a1 and is spaced apart from the side wall of the groove a1, and the column portion 14k is fitted in the through-hole a2; the inner diameter D1 of the through-hole a2, the inner diameter D2 of the groove a1, the outer diameter D3 of the boss portion 14g, and the outer diameter D4 of the column portion 14k satisfy: D4<D1<D3, 0.7D2<D3<D2.

[0116] D4<D1<D3. On the one hand, it makes it easier to insert the column part 14k into the through hole a2. On the other hand, during the process of inserting the sealing nail 14, when the boss part 14g is limited by the bottom of the groove a1, it indicates that the sealing nail 14 is installed in place, and the installation of the sealing nail 14 is more reliable.

[0117] 0.7D2<D3<D2, indicating that there is a certain gap between the boss portion 14g and the side wall of the sink a1, which can be used for welding the gap between the sealing pin 14 and the injection hole 11a to improve the sealing effect.

[0118] In some embodiments, combined Figure 10 and Figure 12 It is understood that the aperture D5 of the injection channel 34r satisfies: D5>D1. In this way, the electrolyte can smoothly flow from the injection hole 11a into the injection channel 34r without leakage.

[0119] In some embodiments, reference Figure 3 and Figure 14 The battery cell 100 further includes an insulating support member 50, which is disposed at the tab end J and opposite to the thermally conductive adhesive 40. The insulating support member 50 is provided with a hollow portion 50u extending through the thickness direction Z of the cover plate 11, and the hollow portion 50u is sleeved around the outer periphery of the tab 21.

[0120] Specifically, the hollow portion 50 u may be a hole structure or a slot structure, as long as it can be sleeved around the outer periphery of the tab 21 .

[0121] The insulating support 50 provides insulation and reinforces the separation between the cover plate 11 and the electrode assembly 20. The insulating support 50 supports the tab end J. The tab 21 at the tab end J is sequentially penetrated by a hollow portion 50u and an opening 30m, extending into the glue-filled space 30h. The tab 21 is typically thin in shape, and the hollow portion 50u is positioned around the periphery of the tab 21, providing some support and enhancing its structural stability.

[0122] Specifically, the insulating filler 30 and the insulating support 50 in the embodiment of the present application can be made of polymer materials with good insulating properties, such as nylon (Polyamide, PA for short), polycarbonate (Polycarbonate, PC for short), polybutylene terephthalate (Polybutylene terephthalate, PBT for short), acrylonitrile-styrene-butadiene copolymer (Acrylonitrile Butadiene Styrene, ABS for short), etc., and fillers that enhance thermal conductivity and insulation (such as Al2O3, AlN, BN, MgO, ZnO, NiO, Si3N4, etc.) can also be added to these polymer materials.

[0123] Figure 13 Shown Figure 2 Enlarged schematic diagram of point III in the middle. Figure 14 Schematic diagrams of the structures of the insulating support member 50 of some embodiments are shown. Figure 15 Shown Figure 14 Another orientation view of the insulating support member 50 is shown.

[0124] It is worth noting that, in one embodiment, Figure 13 As shown, the tab 21 includes a root segment 21a and a tail segment 21b that are intersectingly arranged, and a curved segment 21c that is zigzag connected between the root segment 21a and the tail segment 21b. The tail segment 21b is located in the glue-filled space 30h and is welded to the pole 12. The root segment 21a is penetrated by a hollow position 50u; the thermal conductive glue 40 at least covers the tail segment 21b.

[0125] Specifically, the thermally conductive adhesive 40 may also cover the bent section 21c. In actual use, before the tab 21 is bent, the electrode assembly 20 is in a horizontal position, with its tab end J and the cover plate 11 staggered in a horizontal plane. Because the tab 21 protrudes from the tab end J, the tab 21 is approximately horizontal, making it easier to weld it to the terminal post 12 within the adhesive-filled space 30h. After the tail section 21b of the tab 21 is welded to the terminal post 12, the tab 21 is bent until its tab end J is aligned with the cover plate 11. Specifically, the root section 21a of the tab 21 is provided with a hollow portion 50u.

[0126] Specifically in the embodiment, refer to Figure 14 and Figure 15 The hollow position 50u includes a strip-shaped support groove u1, one end of which is closed in the longitudinal direction and the other end is configured as an opening u11. The insulating support member 50 allows the tab 21 to be inserted into the support groove u1 through the opening u11.

[0127] When the cover plate 11 is a square plate, the longitudinal direction of the support groove u1 corresponds to the length direction X of the cover plate 11 .

[0128] In actual operation, the opening u11 of the support slot u1 is oriented toward the tab 21, and the insulating support member 50 is moved along the tab end J in the longitudinal direction of the support slot u1. During this process, the tab 21 is continuously inserted into the support slot u1 from the opening u11 until it is fully inserted (for example, when it abuts against the closed end). Typically, the width of the support slot u1 (the dimension of the support slot u1 in a direction perpendicular to its longitudinal direction) is slightly greater than or equal to the width of the tab 21. This facilitates insertion of the tab 21 while allowing the supporting insulating member to effectively support the tab 21.

[0129] In this way, the assembly process of the insulating support member 50 and the tab 21 is simpler and easier to implement.

[0130] In some embodiments, reference Figure 14 and Figure 15 The opening u11 of the support groove u1 is arranged in a trumpet shape, and its large-diameter end is arranged away from the closed end of the support groove u1 relative to its small-diameter end.

[0131] The size of the opening u11 of the support groove u1 in the groove width direction decreases from the large-diameter end to the small-diameter end.

[0132] When inserting the tab 21, the tab 21 first passes through the large diameter end of the opening u11 and then through the small diameter end of the opening u11 into the support groove u1. The opening u11 is designed to be trumpet-shaped, making it easier for the tab 21 to be inserted into the support groove u1.

[0133] Figure 16 A partial structural schematic diagram of a battery cell 100 according to some embodiments is shown.

[0134] In some embodiments, combined Figure 2 、 Figure 3 and Figure 16 It is understood that multiple tabs 21 are spaced apart and arranged side by side along the longitudinal direction of the support slot u1. Two insulating support members 50 are provided, with adjacent tabs 21 extending through the support slot u1 of one insulating support member 50, and the remaining adjacent tabs 21 extending through the support slot u1 of the other insulating support member 50. The support slots u1 of the two insulating support members 50 are spaced apart, and the openings u11 are arranged opposite each other.

[0135] Obviously, the term "adjacent tabs 21" here refers to adjacent tabs along the longitudinal direction of the support slot u1. In one embodiment, multiple tabs 21 are provided at the tab end J of each electrode assembly 20. These multiple tabs 21 are spaced side by side along the longitudinal direction X of the cover plate 11. Specifically, these multiple tabs 21 may include one or more positive tabs and one or more negative tabs. Along the longitudinal direction X of the cover plate 11 (corresponding to the longitudinal direction of the support slot u1), all tabs 21 on each electrode assembly 20 are divided into two groups. One group of tabs 21 is inserted into the support slot u1 of one insulating support member 50, and the other group of tabs 21 is inserted into the support slot u1 of the other insulating support member 50. The support slots u1 of the two insulating support members 50 are configured with their openings u11 facing each other. When the two insulating support members 50 are movable relative to each other along the longitudinal direction of the support slot u1, each group of tabs 21 is inserted into the corresponding support slot u1.

[0136] At this time, at least one tab 21 is inserted into each support groove u1 of each insulating support member 50, which can reduce the number of insulating support members 50 and reduce costs. On the other hand, it can improve the installation efficiency of the insulating support members 50 and thus improve the assembly efficiency of the battery cell 100.

[0137] It is worth noting that the same electrode post 12 can be connected to the electrode tab 21 on one electrode assembly 20 , or can be connected to the electrode tabs 21 on different electrode assemblies 20 at the same time.

[0138] In one embodiment, combining Figure 2 It is understood that in order to improve the performance of the battery cell 100, at least two electrode assemblies 20 are configured inside the battery cell 100. Each of the at least two electrode assemblies 20 has a tab 21 connected to the same pole 12, and these tabs 21 are spaced apart along the direction of the slot width of the support slot u1. It is possible that there are multiple support slots u1 on the insulating support member 50, and the multiple support slots u1 extend in the same longitudinal direction and are arranged side by side in a direction perpendicular to the longitudinal direction. Each support slot u1 corresponds to a tab 21, so that the same insulating support member 50 can support multiple tabs 21 connected to the same pole 12, thereby improving the assembly efficiency of the battery cell 100 and reducing costs.

[0139] Of course, only one support slot u1 may be provided on the insulating support 50 , and each pole tab 21 may be correspondingly inserted into the support slot u1 of the insulating support 50 , or multiple pole tabs 21 connected to the same pole 12 may be correspondingly inserted into the support slot u1 of the insulating support 50 at the same time.

[0140] In one specific embodiment, two electrode assemblies 20 and two insulating supports 50 are each configured. Each electrode assembly 20 is configured with multiple tabs 21 on the tab end J at the same end. All tabs 21 on each electrode assembly 20 are spaced apart along the length direction X of the cover plate 11, and all tabs 21 of the two electrode assemblies 20 are arranged in a one-to-one correspondence along the width direction Y of the cover plate 11. The two corresponding tabs 21 on the two electrode assemblies 20 are connected to the same pole 12 and are respectively inserted into two different support grooves u1 on the same insulating support member 50. The openings u11 of the support grooves u1 on the two insulating supports 50 are arranged opposite each other. As recorded above, the support groove u1 of one of the insulating supports 50 is inserted into the adjacent portion of the tabs 21 in the length direction X of the cover plate 11, and the support groove u1 of the other insulating support member 50 is inserted into the other adjacent portion of the tabs 21.

[0141] In some embodiments, combined Figure 3 It is understood that a liquid injection hole 11 a is provided on the cover plate 11 , and along the thickness direction Z of the cover plate 11 , the projection of the insulating support member 50 is staggered with the projection of the liquid injection hole 11 a .

[0142] Specifically, in one example (such as Figure 3 As shown, two insulating support members 50 are provided, spaced apart in the longitudinal direction X of the cover plate 11, with the space between them corresponding to the injection hole 11a. In other examples, a clearance hole may also be provided in the insulating support member 50, with the clearance hole and the injection hole 11a being arranged opposite each other.

[0143] When the above-mentioned protrusion 34 is provided on the insulating filler 30 , the projection of the protrusion 34 includes the projection of the injection hole 11 a , and the projection of the protrusion 34 is set to be staggered with the projection of the insulating support 50 .

[0144] At this time, the insulating support 50 will not hinder the electrolyte from flowing toward the tab end J, which is conducive to the electrolyte smoothly infiltrating the electrode assembly 20.

[0145] In some embodiments, reference Figure 14 、 Figure 15 and Figure 16 The insulating support member 50 is provided with a liquid hole 50v, which connects the liquid injection hole 11a and the electrode assembly 20, and is staggered with the hollow position 50u.

[0146] Specifically, the liquid-passing hole 50v is disposed throughout the insulating support member 50 along the thickness direction Z of the cover plate 11. It is staggered with the hollow portion 50u. This prevents the tab 21 in the hollow portion 50u from interfering with the liquid-passing hole 50v and affecting its flow. Multiple liquid-passing holes 50v are typically provided on the insulating support member 50 to increase liquid-passing capacity. These multiple liquid-passing holes 50v are dispersed throughout the insulating support member 50 to allow electrolyte to flow to multiple locations in the electrode assembly 20.

[0147] Since the insulating support 50 is supported on the tab end J, it will, to a certain extent, hinder the flow of electrolyte to the electrode assembly 20. In this case, the provision of the liquid hole 50v on the insulating support 50 can increase the path for the electrolyte to flow to the tab end J, allowing the electrolyte to more evenly penetrate the interior of the electrode assembly 20, thereby improving the circulation capacity of the electrode assembly 20.

[0148] In some embodiments, combined Figure 14 and Figure 15 The insulating support member 50 includes a first end surface d1 and a second end surface d2 disposed opposite to each other along the thickness direction Z of the cover plate 11. The first end surface d1 is configured as a planar structure that fits the electrode assembly 20. A reinforcing rib 51 is provided on the second end surface d2, and the hollow portion 50u is penetrated by the reinforcing rib 51.

[0149] The first end surface d1 is flat and has a larger contact area with the tab end J. The pressure exerted by the insulating support 50 on the electrode assembly 20 is more uniform, thus preventing the electrode assembly 20 from being locally squeezed and causing safety problems.

[0150] The second end surface d2 of the insulating support member 50 can be provided with a plurality of reinforcing ribs 51. Each rib 51 is arranged in a strip shape, and the plurality of reinforcing ribs 51 can be crisscrossed to form a mesh structure. The provision of the reinforcing ribs 51 not only enhances the overall strength of the insulating support member 50, but also, the hollow portions 50u extending through the reinforcing ribs 51 enhance the support provided by the insulating support member 50 to the tab 21 passing through the hollow portions 50u.

[0151] It is worth mentioning that a liquid hole 50v is provided on the insulating support 50. Since the liquid hole 50v passes through the second end surface d2, even if a reinforcing rib 51 is provided on the second end surface d2, the electrolyte can be prevented from accumulating on the second end surface d2, thereby ensuring smooth outflow of the electrolyte.

[0152] Figure 17 and Figure 18 Schematic diagrams of battery cells 100 in different orientations according to some embodiments are shown.

[0153] In some embodiments, combined Figure 17 and Figure 18It is understood that the cover plate 11 has an outer end surface W set away from the electrode assembly 20, and one end surface of each pole 12 protruding from the outer end surface W is a first flow surface GL1. The area S1 of the first flow surface GL1 of all poles 12 and the area S2 of the outer end surface W satisfy: 0.45S2≤S1<S2.

[0154] It can be understood that the pole 12 is arranged to protrude from the outer end surface W of the cover plate 11. One end surface of the pole 12 in the thickness direction Z of the cover plate 11 is the first flow surface GL1. The first flow surface GL1 is located outside the battery cell 100, opposite to the electrode assembly 20, and is located at the end of the pole 12 protruding from the outer end surface W. The first flow surface GL1 of the pole 12 and the outer end surface W of the cover plate 11 can be, but are not limited to, planes. Area S1 can be understood as the sum of the projected areas of the first flow surfaces GL1 of all poles 12 in the thickness direction Z of the cover plate 11. Area S2 can be understood as the sum of the projected areas of the outer end surfaces W in the thickness direction Z of the cover plate 11.

[0155] Generally, the shape and size of each of the poles 12 are consistent, and the areas of the first flow-through surfaces GL1 thereof are the same.

[0156] In actual use, the pole 12 connects to the wires, conductive bars, etc. through the first flow-through surface GL1 to connect to the external circuit. If the outer end surface W of the cover plate 11 has the same dimensions, the larger the value of S1 / S2, the larger the area S1 of the first flow-through surface GL1 of all poles 12. This increases the contact area between the pole 12 and the wires, conductive bars, etc., reduces the contact resistance, strengthens the current carrying capacity of the pole 12, and improves the current transmission efficiency. Furthermore, a larger first flow-through surface GL1 area improves heat dissipation between the pole 12 and the external environment, thereby enhancing the heat dissipation capacity of the battery cell 100.

[0157] In this embodiment, the ratio S1 / S2 is within the range of [0.45, 1), so that the area S1 of the first flow surface GL1 of all the poles 12 is larger, which can effectively improve the flow capacity and heat dissipation capacity of the poles 12, thereby improving the performance of the battery cell 100.

[0158] Specifically, S1 / S2 can be selected to be 0.45, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, or any value between adjacent selected values. Furthermore, to ensure the strength of the cover 11 and the electrical clearance between the poles 12, S1 / S2 ≤ 0.8.

[0159] In some embodiments, each pole 12 has a second flow surface GL2 disposed opposite to the first flow surface GL1 , and the area S1 ′ of the second flow surface GL2 of all poles 12 and the area S2 of the outer end satisfy 0.5S2 ≤ S1 ′ < S2 .

[0160] The other end surface of the electrode 12 in the thickness direction Z of the cover plate 11 is the second flow surface GL2. The second flow surface GL2 faces the electrode assembly 20 and is connected to the electrode tab 21. The second flow surface GL2 can be, but is not limited to, a plane. The area S1' can be understood as the sum of the projected areas of the second flow surfaces GL2 of all the electrodes 12 in the thickness direction Z of the cover plate 11.

[0161] A larger S1' / S2 value increases the area S1' of the second current-passing surface GL2 of all the terminals 12. At the same current, this not only reduces the internal resistance of the battery cell 100 but also disperses the current distribution, lowering current density and minimizing polarization caused by excessive local current density, thereby improving charge and discharge efficiency. Furthermore, it facilitates the conduction of internal heat from the battery cell 100 to the external environment through the terminals 12, lowering operating temperatures and preventing performance degradation or safety hazards (such as thermal runaway) caused by overheating.

[0162] In this embodiment, the ratio S1' / S2 is within the range of [0.5, 1), and the area S1' of the second current flow surface GL2 of all the poles 12 is large, which can effectively reduce the current density, improve the charging and discharging efficiency, and enhance the heat dissipation and thermal conductivity inside the battery cell 100, thereby improving the performance of the battery cell 100.

[0163] Specifically, S1' / S2 can be selected to be 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, or any value between adjacent selected values. Furthermore, to ensure the strength of the cover 11 and the electrical clearance between the poles 12, S1' / S2 ≤ 0.8.

[0164] In some embodiments, the thermally conductive adhesive 40 can insulate and coat the side of the electrode post 12 facing the tab 21, thereby maintaining electrical clearance between the electrode posts 12 within adjacent battery cells 100 and maximizing the projected area of ​​the second flow surface GL2. The thermally conductive adhesive 40 is insulating and can coat the entire side of the electrode post 12 facing the tab 21 (including the weld area between the electrode post 12 and the tab 21), thereby covering the second flow surface GL2 of the electrode post 12 and achieving electrical isolation between adjacent electrode posts 12.

[0165] Based on this, the projected area of ​​the second flow surface GL2 of the pole 12 can be larger than the projected area of ​​the first flow surface GL1 of the pole 12. That is, S1' is larger than S1. When the second flow surface GL2 of the pole 12 is designed to be larger, the heat generated inside the battery cell is reduced. At the same time, the larger contact area can provide more flow paths for the current, so that the current is evenly distributed in the connection area between the pole 12 and the tab 21, avoiding local overheating caused by excessive local current density. In addition, it can also increase the connection strength between the tab 21 and the pole 12, so that it can withstand greater mechanical stress and avoid problems such as loosening and breaking the connection caused by vibration and impact. In addition, the projected area of ​​the first flow surface GL1 of the pole 12 is designed to be smaller than the projected area of ​​the second flow surface GL2, so that more space can be reserved for the pole 12 on the side of the cover plate 11 facing away from the electrode assembly 20. This can facilitate the spatial layout of the pole 12 and the external conductive bar, improve the reliability of the connection between the pole 12 and the conductive bar, and ensure the electrical clearance between adjacent poles 12.

[0166] In some embodiments, reference Figure 2 The end cover 10 includes N poles 12 , which are arranged side by side and spaced apart along the length direction X of the cover plate 11 , where N is ≥ 4 and is an even number.

[0167] In conventional designs, one or two poles 12 are provided on the same end cap 10. In this embodiment, an even number of four or more poles 12 are provided on the end cap 10. This, on the one hand, increases the flow area between the poles 12 and the tabs 21, and between the poles 12 and the external circuit. This not only reduces the flow resistance of the battery cell 100, but also reduces the flow density of the battery cell 100, reduces local temperature rise, and improves the charge and discharge efficiency and heat dissipation capacity of the battery cell 100.

[0168] On the other hand, the poles 12 are dispersed relative to the cover plate 11, and a plurality of pole ears 21 can be correspondingly configured on the electrode assembly 20 inside the battery cell 100, which are connected one-to-one with the poles 12. At this time, the current transmission of the electrode assembly 20 can be dispersed at multiple positions, which helps to improve the temperature rise uniformity of the electrode assembly 20 and improve the temperature uniformity of the battery cell 100.

[0169] Specifically, in the embodiment, N poles 12 form a plurality of pole groups, each pole group including two poles 12 with opposite polarities. All poles 12 are arranged at intervals along the length direction X of the cover plate 11.

[0170] That is, among the plurality of poles 12, some poles 12 are positive poles, and the other poles 12 are negative poles, and the number of positive poles and negative poles is the same. Alternatively, the positive poles and negative poles are arranged alternately.

[0171] In this case, multiple positive and negative electrode posts are arranged on the same end cap 10, which not only improves the charging and discharging efficiency and heat dissipation of the battery cells 100, but also increases the space utilization of the battery cells 100 in the thickness direction Z of the cover plate 11. Furthermore, the same liquid cooling plate can be used to cool the battery cells 100, reducing the cost of liquid cooling for the battery.

[0172] In a specific embodiment, if Figure 2 As shown, the number of poles 12 is configured as 4, including two positive poles and two negative poles, and the positive poles and negative poles are arranged alternately. In this way, under the same S1 and S1', the assembly efficiency of the battery cell 100 is higher than that of setting more poles 12.

[0173] Figure 19 Schematic diagrams of the structures of the end caps 10 of some embodiments are shown. Figure 20 Schematic cross-sectional views of the end cap 10 are shown according to some embodiments.

[0174] Specifically in the embodiment, refer to Figure 19 The dimension of the first flow surface GL1 of each pole 12 in the length direction X of the cover plate 11 is b, and the dimension of the first flow surface GL1 of each pole 12 in the width direction Y of the cover plate 11 is a. In the plane of the outer end surface W, the interval between the first flow surfaces GL1 of adjacent poles 12 is m, the distance between the first flow surfaces GL1 of the first and last poles 12 and the edge of the outer end surface W in the length direction X is p, and the distance between the first flow surfaces GL1 of all poles 12 and the edge of the outer end surface W in the width direction Y is n, satisfying:

[0175] S2=(a+2n)*[N*b+2p+(N-1)*m], where m≥2mm, n≥4mm, and p≥4mm.

[0176] The poles 12 are arranged at equal intervals along the length direction X of the cover plate 11. m, n, and p determine the placement of the poles 12 on the cover plate 11. The smaller the three, the larger the area occupied by the first current-passing surface GL1 of the pole 12 on the outer end surface W of the cover plate 11, provided the size of the cover plate 11 remains unchanged. As described above, the larger the area of ​​the first current-passing surface GL1, the larger the contact area between the pole 12 and the wires, conductive bars, etc., the smaller the contact resistance, the stronger the current-passing capacity of the pole 12, and the higher the current transmission efficiency. At the same time, a large area of ​​the first current-passing surface GL1 can increase the heat dissipation between the pole 12 and the outside, thereby improving the heat dissipation capacity of the battery cell 100. Of course, the sizes of m, n, and p cannot be infinitely small; smaller sizes indicate lower strength of the cover plate 11.

[0177] When m, n, and p each satisfy the above relationship, both the strength of the cover plate 11 and the performance of the battery cell 100 can be taken into account. Further, m≤5mm, n≤10mm, and p≤10mm can be used. In this case, both the strength of the cover plate 11 and the performance of the battery cell 100 can be taken into account.

[0178] In practical applications, a square cover 11 can be designed based on the above dimensions. Specifically, (a + 2n) can be considered the width of cover 11, and [N * b + 2p + (N - 1) * m] can be considered the length of cover 11. This determines the area S2 of the outer end surface W of cover 11. Once the dimensions of pole 12 and the spacing n, p, and m are determined, the dimensions of cover 11 can be determined based on these data, eliminating the need to consider the space occupied by other structures on cover 11, simplifying the design of cover 11.

[0179] Specifically in the embodiment, see Figure 19 The projection of the terminal post 12 along the thickness direction Z of the cover plate 11 is rectangular. Typically, the cover plate 11 is square. In this case, designing the terminal post 12 as a square structure not only improves the appearance of the end cap 10 but also simplifies its structure. Given the same m, n, and p values, the larger area for the terminal post 12 significantly improves the performance of the battery cell 100.

[0180] Of course, in other embodiments, the pole 12 may also be cylindrical or have other prismatic structures.

[0181] In some embodiments, the total length G1 of the first flow surfaces GL1 of all poles 12 in the length direction X of the cover plate 11, the total length G0 of the cover plate 11, and the total length G2 of the second flow surfaces GL2 of all poles 12 in the length direction X satisfy: 0.5G0<G1<G2<G0.

[0182] Specifically, to simplify the design, the first flow surface GL1 and the second flow surface GL2 may have the same dimensions in the width direction Y of the cover plate 11, and may have different dimensions in the length direction X of the cover plate 11, so that their areas are unequal. To further simplify the design, the first flow surface GL1 of each pole 12 may have the same dimensions in all directions, and the second flow surface GL2 of each pole 12 may have the same dimensions in all directions.

[0183] When 0.5G0<G1<G2<G0, when the width dimensions of the first flow surface GL1 and the second flow surface GL2 are the same, the area of ​​the first flow surface GL1 can be made smaller than the area of ​​the second flow surface GL2, thereby reducing the flow density of the battery cell 100 and improving its charging and discharging efficiency, while also taking into account the strength of the cover plate 11 and the structural compactness of the battery cell 100.

[0184] In some embodiments, reference Figure 20 The cover plate 11 is provided with a liquid injection hole 11a extending through its outer end surface W. Each pole 12 is provided protruding from the outer end surface W. Along the length direction X of the cover plate 11, a spacer T is formed between each two adjacent poles 12. The liquid injection hole 11a is arranged in a portion of the spacer T. The spacer T with the liquid injection hole 11a has a dimension m1 along the length direction X, and a diameter D2 of the liquid injection hole 11a. The spacer T without the liquid injection hole 11a has a dimension m2 along the length direction X, satisfying the following: 0.4m1≤D2<m1; m2≤m1.

[0185] The spacer T refers to the area on the cover plate 11 between two adjacent poles 12 along its length direction X. The injection hole 11a is used to fill the electrolyte. The injection hole 11a is located within a portion of the spacer T and extends through the spacer T. There is typically one injection hole 11a, located within each spacer T. The diameter D2 of the injection hole 11a refers to the maximum projection dimension of the injection hole 11a along the thickness direction Z of the cover plate 11. When the injection hole 11a includes the aforementioned recessed groove a1 and the aforementioned through-hole a2, its maximum projection dimension is the inner diameter of the recessed groove a1.

[0186] In this embodiment, m2 ≤ m1, meaning the length of the spacer T without the injection holes 11a is shorter than the length of the spacer T with the injection holes 11a. This facilitates the placement of the injection holes 11a. Furthermore, 0.4m1 ≤ D2 < m1, meaning the area occupied by the injection holes 11a in the spacer T is appropriate, minimizing the impact on the strength of the spacer T.

[0187] In some embodiments, reference Figure 16 It is understood that there are multiple tabs 21, which are spaced apart along the length direction X of the cover plate 11. Each pole post 12 is welded to a corresponding tab 21, and adjacent tabs 21 have opposite polarity. In the length direction X of the cover plate 11, the length L1 of the negative polarity tab 21 and the length L2 of the positive polarity tab 21 satisfy the following relationship: L1 ≤ L2.

[0188] The tab 21 with a negative polarity is called a negative tab, and the tab 21 with a positive polarity is called a positive tab. The negative tab is usually made of copper, and the positive tab is usually made of aluminum. When L1=L2, it means that the length L2 of the positive tab is the same as the length L1 of the negative tab. When the width dimensions of the positive tab and the negative tab are the same, the size structure of each tab 21 is the same, thereby simplifying the preparation of the electrode assembly 20. Since the conductivity of aluminum is weaker than that of copper, when L1<L2, when the width dimensions of the positive tab and the negative tab are the same, the flow capacity of the positive tab and the negative tab can be balanced to avoid excessive heat generation of the positive tab.

[0189] In other embodiments, the length L1 of the negative electrode tab 21 and the length L2 of the positive electrode tab 21 satisfy the following: 0.25L2≤L1≤0.9L2. In this case, L1 / L2 is within the range of 0.25 to 0.9. This allows the positive and negative tabs to have the same widths and dimensions, thereby ensuring that their current capacity and heat generation are as closely matched as possible. Specifically, L1 / L2 can be selected from 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.85, 0.9, and any values ​​between adjacent selected values.

[0190] Typically, the dimensions of the electrode tabs 21 in the width direction Y of the cap plate 11 (ie, the width of the electrode tabs 21 ) are equal to each other, which simplifies the preparation of the battery cell 100 .

[0191] In some embodiments, reference Figure 2 The battery cell 100 further includes a housing 60, which includes a receiving cavity with an open end u11. The cover plate 11 covers the open end u11 of the receiving cavity, with the outer end surface W of the cover plate 11 facing away from the receiving cavity. The electrode assembly 20 is received in the receiving cavity. The housing 60 can be made of steel, aluminum, or the like, and cooperates with the cover plate 11 to form a receiving cavity for accommodating the electrode assembly 20. The housing 60 and the cover plate 11 can be sealed by welding, clamping, or other methods.

[0192] Further to the embodiment, refer to Figure 2 The battery cell 100 further includes a heat-conducting covering 70, which is located in the receiving cavity and covers the electrode assembly 20. The heat-conducting covering 70 has heat-conducting properties and can be graphene or a heat-conducting plastic film (such as PP, PC, etc.).

[0193] At this time, the heat generated by the electrode assembly 20 is transferred to the outer shell 60 through the thermally conductive covering 70. The outer shell 60 can exchange heat with the external liquid cooling structure, thereby improving the heat exchange efficiency between the battery cell 100 and the liquid cooling structure, greatly reducing the working heat of the battery cell 100, and improving the reliability of the battery cell 100.

[0194] Furthermore, in the embodiment, the battery cell 100 further includes an explosion-proof valve (not shown), which is disposed on a side of the housing 60 facing away from the end cover 10 .

[0195] In a specific embodiment of the present application, a battery cell 100 includes the aforementioned end cap 10, a housing 60, an insulating filler 30, an insulating support 50, and an electrode assembly 20. The insulating filler 30 is thermally connected to the cover plate 11 and defines a filler space 30h. An opening 30m is formed on the end of the insulating filler 30 facing the tab end J. The tab 21 on the tab end J, after passing through the support groove u1 of the insulating support 50, extends through the opening 30m into the filler space 30h and is welded to the terminal post 12 extending into the filler space 30h through the avoidance hole 30i on the insulating filler 30. The filler space 30h is filled with thermally conductive adhesive 40, which covers the tab 21 and the terminal post 12. The insulating filler 30 is provided with a boss 34, which is arranged corresponding to the injection hole 11a on the cover plate 11 and has an injection channel 34r connected to the injection hole 11a. The protrusion 34 exceeds the range of the insulating filler 30 and extends toward the tab end J. The insulating support 50 avoids the protrusion 34 to facilitate the electrolyte to evenly infiltrate the electrode assembly 20.

[0196] Figure 21 A schematic flow chart showing a method for preparing a battery cell 100 according to some embodiments is shown. Figure 22 The state changes of the electrode assembly 20 during the preparation process of the battery cell 100 are shown.

[0197] In addition, please refer to Figure 21 The present application also provides a method for preparing a battery cell 100 , which is applied to the battery cell 100 in any of the above embodiments. The method includes:

[0198] S1 . Pass the pole 12 on the end cover 10 through the avoidance hole 30 i of the insulating filler 30 , so that the pole 12 extends into the filling space 30 h of the insulating filler 30 .

[0199] Specifically, the inner side of the end cap 10 and the cover plate 11 can be turned upward, and the opening 30m of the insulating filler 30 can be turned upward, and the insulating filler 30 can be pressed down from top to bottom, so that the welding section 12c of the pole 12 passes through the avoidance hole 30i of the insulating filler 30 until the insulating filler 30 and the cover plate 11 are abutted. At this time, the welding section 12c is located in the filling space 30h.

[0200] S2. Place the opening 30m of the insulating filler 30 upward, and weld the tab 21 of the electrode assembly 20 in a lying state to the pole 12 located in the filling space 30h. When in a lying state, the tab end J of the electrode assembly 20 is located on one side of the electrode assembly 20 in the horizontal direction.

[0201] like Figure 22In the state shown by the middle dotted line, the electrode assembly 20 is in a flat state, the tab end J of the electrode assembly 20 is roughly vertically arranged, and its tab 21 extends roughly horizontally, passing through the opening 30m, and the tab 21 is welded to the welding section 12c located in the insulating filler 30.

[0202] S3, pouring thermal conductive glue 40 into the glue filling space 30h through the opening 30m;

[0203] The glue delivery pipe of the glue filling equipment extends into the glue filling space 30h through the opening 30m, so that the glue filling space 30h is filled with thermal conductive glue 40. Specifically, the filling thickness of the thermal conductive glue 40 does not exceed the overflow glue channel 33q formed by the partition strip 33, so as to reduce the amount of thermal conductive glue 40 used.

[0204] S4 , bend the tab 21 until the tab end J of the electrode assembly 20 is arranged opposite to the opening 30 m of the insulating filler 30 .

[0205] Specifically, after the thermal conductive adhesive 40 is cured, the tab 21 can be bent and Figure 22 Fold the electrode assembly 20 in the direction indicated by the middle arrow until the tab end J of the electrode assembly 20 faces the opening 30m of the insulating filler 30. At this time, the tab end J is approximately horizontally arranged (as shown in FIG. Figure 21 The state is shown by the solid line).

[0206] In the above-described method for preparing a battery cell 100, the insulating filler 30 is inverted with its opening 30m facing upward. With the electrode assembly 20 in a flat position, the tab 21 is extended through the opening 30m into the filler space 30h. This welding operation to the terminal post 12 within the filler space 30h is simplified and convenient. Furthermore, after the tab 21 and terminal post 12 are welded, thermally conductive adhesive 40 can be poured through the opening 30m, ensuring that the thermally conductive adhesive 40 effectively covers the tab 21 and terminal post 12, and making the pouring process easier to control.

[0207] In other embodiments, when the battery cell 100 includes a thermally conductive coating 70 , before step S4 , the following steps are included:

[0208] S31, covering the outer periphery of the electrode assembly 20 with a thermally conductive covering member 70;

[0209] Specifically, before folding the electrode assembly 20 , the thermally conductive covering member 70 is covered around the periphery of each electrode assembly 20 , which makes it easier to install the thermally conductive covering member 70 .

[0210] In other embodiments, when the battery cell 100 includes an insulating support member 50 and a housing 60 , and the insulating support member 50 includes the aforementioned supporting groove u1 and opening u11 , after step S4 , the following steps are further included:

[0211] S5. Orient the first end face d1 of the insulating support member 50 toward the tab end J of the electrode assembly 20; insert the insulating support member 50 along the extension direction of the support groove u1 through the opening u11 of the support groove u1 of the insulating support member 50 to the outer periphery of the tab 21;

[0212] Specifically, the intermediate component obtained in step S4 can be folded up and down as a whole, so that the end cover 10 faces upward and the electrode assembly 20 faces downward, and then the insulating support 50 is pushed along the pole tab end J so that the pole tab 21 is inserted into the support groove u1 from the opening u11 of the support groove u1 of the insulating support 50.

[0213] S6. Weld the outer shell 60 to the cover plate 11 of the end cap 10 , and ensure that the thermal conductive covering member 70 , the electrode assembly 20 , the insulating filler 30 , and the insulating support member 50 are all located in the accommodating cavity formed by the outer shell 60 and the cover plate 11 .

[0214] Specifically, after the intermediate component obtained in step S5 is placed as a whole into the accommodating cavity of the shell 60 , the cover plate 11 covers the opening u11 end of the shell 60 , and the cover plate 11 and the opening u11 end of the shell 60 are welded.

[0215] In addition, after step S6, conventional processes such as liquid injection and chemical formation may also be generally included. The specific operations of each process are not described here in detail and can be referred to common knowledge.

[0216] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0217] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A battery cell (100), characterized in that: include: An end cover (10) comprises a cover plate (11) and a pole (12) provided on the cover plate (11); An electrode assembly (20) having a tab end (J) disposed facing the cover plate (11), wherein a tab (21) is protruding from the tab end (J); An insulating filler (30) is provided between the electrode assembly (20) and the cover plate (11), and has a filler space (30h) and a avoidance hole (30i) communicating with the filler space (30h); an opening (30m) is provided at one end of the insulating filler (30) facing the tab end (J); the tab (21) extends into the filler space (30h) through the opening (30m); the pole (12) is provided with the avoidance hole (30i) and is connected to the tab (21) in the filler space (30h); and The thermal conductive adhesive (40) is filled into the adhesive filling space (30h) through the opening (30m) and covers the tab (21) and the pole (12).

2. The battery cell (100) according to claim 1, characterized in that The projection of the opening (30m) along the thickness direction (Z) of the cover plate (11) includes the projection of the tab end (J) along the thickness direction (Z); and / or, The pole (12) comprises a matching section (12b), and the matching section (12b) matches the avoidance hole (30i) by itself or through a sealing member (13).

3. The battery cell (100) according to claim 2, characterized in that The pole (12) comprises the matching section (12b) and a welding section (12c) adjacent to and connected to the matching section (12b); the welding section (12c) is located in the glue-filled space (30h) and welded to the pole lug (21); along the thickness direction (Z) of the cover plate (11), the projection of the welding section (12c) exceeds the projection of the matching section (12b) and the projection of the avoidance hole (30i); The inner wall of the avoidance hole (30i) is configured to be deformable.

4. The battery cell (100) according to claim 3, characterized in that The inner wall of the avoidance hole (30i) is recessed to form a plurality of notches (30n), and the plurality of notches (30n) are arranged at intervals along the circumference of the avoidance hole (30i); Each of the notches (30n) penetrates the wall of the insulating filler (30) along the thickness direction (Z), so that the inner wall of the avoidance hole (30i) can be bent and deformed.

5. The battery cell (100) according to any one of claims 1 to 4, characterized in that: The insulating filler (30) includes a separation strip (33) and / or a protruding column (34); The partition bar (33) is located in the glue-filled space (30h) and divides the glue-filled space (30h) into a main space (h1) and a glue-overflow space (h2); the avoidance hole (30i) is connected to the main space (h1), and the tab (21) extends into the main space (h1); the partition bar (33) forms a glue-overflow channel (33q) that connects the glue-overflow space (h2) with the main space (h1); at least the main space (h1) is filled with the thermal conductive glue (40); The cover plate (11) is provided with a liquid injection hole (11a); the convex column (34) is located in the glue filling space (30h), extends toward the pole lug end (J) and passes through the opening (30m), and is spaced from the pole lug end (J); a liquid injection channel (34r) connected to the liquid injection hole (11a) is formed in the convex column (34); along the thickness direction (Z) of the cover plate (11), the projection of the outlet end of the liquid injection hole (11a) is located within the projection range of the inlet end of the liquid injection channel (34r).

6. The battery cell (100) according to any one of claims 1 to 4, characterized in that: The battery cell (100) further includes an insulating support member (50), wherein the insulating support member (50) is provided at the tab end (J) and is arranged opposite to the thermal conductive adhesive (40); The insulating support member (50) is provided with a hollow portion (50u) extending through the cover plate (11) in the thickness direction (Z), and the hollow portion (50u) is sleeved on the periphery of the tab (21).

7. The battery cell (100) according to any one of claims 1 to 4, characterized in that: The cover plate (11) has an outer end surface (W) disposed away from the electrode assembly (20); each pole (12) has a first flow-through surface (GL1) disposed away from the electrode assembly (20); the area S1 of the first flow-through surface (GL1) of all the poles (12) and the area S2 of the outer end surface (W) satisfy: 0.45S2≤S1<S2; Each pole (12) has a second flow surface (GL2) disposed opposite to the first flow surface (GL1), and the area S1' of the second flow surface (GL2) of all poles (12) and the area S2 of the outer end surface (W) satisfy: 0.5S2≤S1'<S2.

8. The battery cell (100) according to claim 7, characterized in that The end cover (10) comprises N poles (12), and the N poles (12) are arranged side by side and spaced apart along the length direction (X) of the cover plate (11), where N is greater than or equal to 4 and is an even number; The dimension of the first flow surface (GL1) of each pole (12) in the length direction (X) of the cover plate (11) is b, and the dimension of the first flow surface (GL1) of each pole (12) in the width direction (Y) of the cover plate (11) is a; In the plane where the outer end surface (W) is located, the interval between the first flow surfaces (GL1) of adjacent poles (12) is m, the distance between the first flow surfaces (GL1) of the first and last poles (12) and the edge of the outer end surface (W) in the length direction (X) is p, and the distance between the first flow surfaces (GL1) of all the poles (12) and the edge of the outer end surface (W) in the width direction (Y) is n; Satisfies: S2=(a+2n)*[N*b+2p+(N-1)*m], where m≥2mm, n≥4mm, p≥4mm.

9. The battery cell (100) according to any one of claims 1 to 4, characterized in that: There are a plurality of pole tabs (21), and the plurality of pole tabs (21) are spaced apart along the length direction (X) of the cover plate (11). Each pole (12) is welded to a corresponding pole tab (21), and the polarities of adjacent pole tabs (21) are opposite. In the length direction (X) of the cover plate (11), the length L1 of the tab (21) of the negative polarity and the length L2 of the tab (21) of the positive polarity satisfy: L1≤L2, or, 0.25L2≤L1≤0.9L2.

10. A method for preparing a battery cell (100), applied to the battery cell (100) according to any one of claims 1 to 9, characterized in that: The preparation method comprises: Passing the pole (12) on the end cover (10) through the avoidance hole (30i) of the insulating filler (30) so that the pole (12) extends into the filler space (30h) of the insulating filler (30); The opening (30m) of the insulating filler (30) is facing upward, and the tab (21) of the electrode assembly (20) in a lying state is welded to the pole (12) located in the filler space (30h); when in the lying state, the tab end (J) of the electrode assembly (20) is located on one side of the electrode assembly (20) in the horizontal direction; pouring heat-conducting glue (40) into the glue-filling space (30h) through the opening (30m); The tab (21) is bent and the electrode assembly (20) is turned over until the tab end (J) of the electrode assembly (20) is arranged opposite to the opening (30m) of the insulating filler (30).

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