Battery cell cover plate assembly and battery cell assembly

Abstract

The utility model relates to the technical field of batteries, and discloses a battery cell cover plate assembly and a battery cell assembly.The battery cell cover plate assembly comprises a connecting piece, the connecting piece comprises a pole connecting part and a tab connecting part which are connected in sequence, the top surface of the tab connecting part forms a connecting surface used for being connected with a tab, and the top surface of the pole connecting part is provided with a vertically extending through hole; the pole is provided with a connecting column matched with the through hole in an inserted mode, a riveting section is formed at the lower end of the connecting column and penetrates through the through hole, and a riveting table matched with the peripheral face of the through hole is formed on the riveting section; the connecting column penetrates through the through hole, then forms the riveting table matched with the peripheral surface of the through hole through riveting, and then is welded and fixed, the fixed connection mode is stable and reliable, the area of the welding part of the pole and the connecting piece is large, and the stability and the reliability of the pole and the connecting piece after welding can be effectively improved; when the tab connecting part is pulled down by the tab, the pole and the pole connecting part can be matched more tightly.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a cell cover plate assembly and a cell assembly. Background Art

[0002] With the rapid development of new energy technologies, power batteries have been increasingly widely used in various electric tools and new energy vehicles due to their excellent characteristics. The safety during the use of power batteries is one of the indicators that cannot be ignored. Power batteries not only need to have a high capacity but also should have good reliability in use. As an important part of power batteries, the cover plate assembly plays a role in draining and sealing the power batteries.

[0003] At present, the two poles of existing power batteries are mainly connected to the corresponding pole columns through connecting pieces. The connecting pieces have planar connecting surfaces, and the pole columns are correspondingly provided with mating surfaces. The mating surfaces of the pole columns and the connecting surfaces of the connecting pieces are welded. Although the power batteries applying this assembly connection method have a relatively simple structure, during long-term use, the connection positions between the pole columns and the connecting pieces are prone to break and separate under vibration or bumpy conditions, and then a short-circuit phenomenon occurs, resulting in poor reliability in the use of power batteries. Summary of the Utility Model

[0004] In view of this, the utility model provides a cell cover plate assembly and a cell assembly to solve the problem of poor reliability of the connection method between the pole column and the connecting piece in existing power batteries.

[0005] In a first aspect, the utility model provides a cell cover plate assembly, including: a connecting piece, including a pole column connecting part and an ear connecting part connected in sequence. The top surface of the ear connecting part forms a connecting surface for connecting with the ear. The top surface of the pole column connecting part forms a first mating surface, and a vertically extending through hole is arranged on the first mating surface; a pole column, the bottom of which forms a second mating surface that mates with the first mating surface. The pole column has a connecting column at the position of the second mating surface that is inserted and mated with the through hole. The pole column is welded and connected to the through hole of the connecting piece through the connecting column. The lower end of the connecting column forms a riveting section and passes through the through hole, and the riveting section forms a riveting table that mates with the peripheral surface of the through hole; a cover plate, located above the connecting piece and having an assembly hole for the pole column to pass through.

[0006] Beneficial effects: a through hole is arranged on the first mating surface and a connecting column is arranged on the second mating surface. After the connecting column passes through the through hole, a riveted platform matching with the peripheral surface of the through hole is formed by riveting, and then it is fixed by welding. The fixed connection method is stable and reliable. The welding part between the pole column and the connecting piece is not a single plane connection and the area of ​​the welding connection is large, which can effectively improve the stability and reliability of the pole column and the connecting piece after welding. At the same time, the weld between the through hole and the connecting column can also improve the current passing capacity at this position. In addition, since the connection surface connected to the pole ear is located at the top of the pole ear connecting part, after the pole ear and the pole ear connecting part are connected, not only the structure is more compact and the space occupied is smaller, but also when the pole ear pulls down the pole ear connecting part, one side of the pole column connecting part will tend to curl up, so that the pole column and the pole column connecting part can be more closely matched, reducing the risk of separation, and effectively solving the problem of poor reliability of the connection method between the pole column and the connecting piece in the existing power battery.

[0007] In an optional embodiment, the through hole includes a first hole segment and a second hole segment arranged in sequence from top to bottom, the hole diameter of the second hole segment is larger than the hole diameter of the first hole segment, the step surface connecting the second hole segment and the first hole segment forms a riveted surface, and the riveting table is riveted to the riveted surface and the inner wall of the second hole segment respectively.

[0008] Beneficial effects: This type of riveting has a larger contact surface at the mating position, and the connection strength and reliability after subsequent welding are also higher. In addition, the riveting table is located in the second hole segment, which can improve the flatness of the riveting table and the peripheral surface of the second hole segment.

[0009] In an optional embodiment, the riveted surface is an annular surface, the width of the riveted surface along the radial direction is greater than or equal to 0.15 mm, and / or the length of the second hole segment along the axial direction is greater than or equal to 0.35 mm.

[0010] Beneficial effect: The second hole segment of this size can ensure the connection strength between the riveting platform and the second hole segment, and can also ensure the reliability of the subsequent welding process.

[0011] In an optional embodiment, the top of the pole connecting part has an upwardly protruding boss, and the bottom of the pole connecting part forms a groove upwardly corresponding to the position of the boss, the top surface of the boss forms a first mating surface, the through hole is located on the boss and connected to the groove, and the top surface of the groove is recessed upward around the position of the through hole to form a welding groove.

[0012] Beneficial effect: The pole-to-pole connection is achieved through penetration welding at the position of the welding groove, which further improves the connection strength and can also accommodate the welding points generated there, improves the flatness of the top surface of the groove, and prevents the welding points from protruding downward and interfering with other components.

[0013] In an alternative embodiment, the welding groove is an annular groove, the through hole is a round hole, the welding groove is disposed close to the side wall of the groove, and the distance from the inner side wall of the welding groove to the inner wall of the through hole along the radial direction is greater than or equal to 1.2 mm.

[0014] Advantageous effects: The welding groove of such dimensions can prevent the welding bead width at the welding groove from overlapping with that at the through hole position, and can reduce the risk of gas holes and welding slag.

[0015] In an alternative embodiment, it further includes a first insulating member disposed between the connecting piece and the cover plate. The welding groove is an annular groove, the boss is a frustum of a cone, and the distance from the outer side wall of the welding groove to the side wall of the boss along the radial direction is greater than or equal to 0.8 mm.

[0016] Advantageous effects: Such a specification and dimension form can, while meeting the connection strength requirements, also improve the safety and reliability during welding at the position of the welding groove, and prevent heat transfer during welding from melting other surrounding components.

[0017] In an alternative embodiment, the depth of the welding groove is greater than or equal to 0.2 mm.

[0018] Advantageous effects: It can prevent the solder joint at this position from protruding downward from the top surface of the groove, and improve the flatness of this local position.

[0019] In an alternative embodiment, one end of the tab connecting portion away from the pole column connecting portion forms a groove along the direction close to the pole column connecting portion, and connection surfaces are respectively formed on the top surfaces of the tab connecting portion on both sides of the groove.

[0020] Advantageous effects: Such a form of the tab connecting portion is lighter in weight, enabling one tab connecting portion to be connected to two tabs simultaneously, and the structural form is simple and reliable.

[0021] In an alternative embodiment, the cover plate includes a main body plate and an assembly plate. The main body plate is assembled and connected to the pole column. The main body plate is provided with a welding hole corresponding to the tab connecting portion, and the assembly plate matches the shape of the welding hole and is assembled in the welding hole.

[0022] Advantageous effects: After the cell cover plate assembly is installed, the tab and the tab connecting portion can be directly welded through the welding hole, which can effectively simplify the assembly steps and improve the production efficiency.

[0023] In a second aspect, the present utility model further provides a cell assembly, which includes: the above-mentioned cell cover plate assembly; a cell, with tabs provided on the top. The tabs include a connecting section and a bent section. The connecting section is located on one side of the tab connecting portion of the cell cover plate assembly. The bent section is connected to the top of the connecting section and extends along the top surface of the tab connecting portion. The tab is welded to the tab connecting portion. Description of the Drawings

[0024] To more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 Three-dimensional schematic diagram of a cell cover assembly of an embodiment of the present utility model without an assembled plate;

[0026] Figure 2 For Figure 1 Cross-sectional view of the cell cover assembly shown after installing the assembled plate;

[0027] Figure 3 For Figure 2 Enlarged schematic diagram of part A of the cell cover assembly shown;

[0028] Figure 4 For Figure 3 Explosion schematic diagram of the connecting piece and the pole column after assembly;

[0029] Figure 5 For Figure 1 Three-dimensional schematic diagram of the connecting piece of the cell cover assembly shown;

[0030] Figure 6 For Figure 1 Three-dimensional schematic diagram of the pole column of the cell cover assembly when not assembled;

[0031] Figure 7 Three-dimensional schematic diagram of a cell assembly of an embodiment of the present utility model

[0032] Figure 8 For Figure 7 Three-dimensional schematic diagram of the cell assembly shown when the housing is not installed;

[0033] Figure 9 For Figure 8 Three-dimensional schematic diagram of the cell assembly shown when the tab is not welded.

[0034] Explanation of reference numerals:

[0035] 1. Connecting piece; 101. Pole column connecting part; 1011. First mating surface; 1012. Boss; 1013. Groove; 1014. Welding groove; 102. Tab connecting part; 1021. Connecting surface; 1022. Through groove; 103. Through hole; 1031. First hole section; 1032. Second hole section; 1033. Riveting surface;

[0036] 2. Terminal; 201. Second mating surface; 202. Connecting post; 203. Riveting platform

[0037] 3. Cover plate; 301. Main body plate; 3011. Welding hole; 302. Assembly plate; 3021. Sealing plate; 3022. Insulating plate

[0038] 4. First insulating part; 5. Second insulating part; 6. Battery cell; 601. Tab; 7. Housing Specific embodiments

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some, but not all, of the embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0040] The following combines Figures 1 to 9 to describe the embodiments of the present utility model.

[0041] According to an embodiment of the present utility model, on the one hand, a battery cell cover plate assembly is provided, including: a connecting piece 1, a terminal 2, and a cover plate 3. The connecting piece 1 includes a terminal connecting portion 101 and a tab connecting portion 102 connected in sequence. The top surface of the tab connecting portion 102 forms a connecting surface 1021 for connecting with the tab 601. The top surface of the terminal connecting portion 101 forms a first mating surface 1011. A through hole 103 extending vertically is provided on the first mating surface 1011. For the terminal 2, a second mating surface 201 that mates with the first mating surface 1011 is formed at the bottom. The position of the terminal 2 at the second mating surface 201 has a connecting post 202 that is inserted and mated with the through hole 103 of the connecting piece 1. The terminal 2 is welded to the through hole 103 of the connecting piece 1 through the connecting post 202. The lower end of the connecting post 202 forms a riveting section and passes through the through hole 103. The riveting section forms a riveting platform 203 that mates with the peripheral surface of the through hole 103. The cover plate 3 is located above the connecting piece 1 and has an assembly hole for the terminal 2 to pass through.

[0042] In the battery cell cover plate assembly of the present embodiment, a through hole 103 is provided on the first mating surface 1011 and a connecting column 202 is provided on the second mating surface 201. After the connecting column 202 passes through the through hole 103, a riveted platform 203 matching the peripheral surface of the through hole 103 is first formed by riveting, and then welded and fixed. The fixed connection method is stable and reliable. The welding part of the pole 2 and the connecting piece 1 is not a single plane connection and the area of ​​the welding connection is large, which can effectively improve the stability and reliability of the welding of the pole 2 and the connecting piece 1. At the same time, the welding between the through hole 103 and the connecting column 202 is stable. The gap can also improve the current passing capacity at this position. In addition, since the connecting surface 1021 connected to the pole lug 601 is located at the top of the pole lug connecting part 102, after the pole lug 601 is connected to the pole lug connecting part 102, not only is the structure more compact and occupies less space, but when the pole lug 601 pulls down the pole lug connecting part 102, one side of the pole connecting part 101 will tend to curl up, so that the pole 2 and the pole connecting part 101 can fit more closely, reducing the risk of separation, and effectively solving the problem of poor reliability of the connection method between the pole and the connecting plate in the existing power battery.

[0043] It should be noted that top refers to Figure 4 The arrow in the middle points to the "up" side, and the bottom refers to Figure 4 The arrow in the middle points to the "down" side, and upward means the side that faces Figure 4 The arrow in the middle points to the "up" direction, and pulling down means going toward Figure 4 Pull in the direction indicated by the arrow in the middle.

[0044] In the related art, the connecting sheet 1 and the pole ear 601 of the battery cell 6 are usually distributed up and down, and the bottom surface of the connecting sheet 1 is connected to the pole ear 601. In order to improve the connection reliability between the two, the pole ear 601 usually needs to be bent and fixed by welding to the bottom surface of the connecting sheet 1 through the outer wall. The pole ear 601 under this connection method needs to occupy a larger space, so that the top of the battery cell assembly has a cavity. In addition, the pole ear 601 will push up the connecting sheet 1, so that the pole connecting part 101 of the connecting sheet 1 will tend to move downward under the action of the lever principle, thereby making the pole connecting part 101 of the connecting sheet 1 easily separated from the pole 2, making the structural stability of the top of the battery cell assembly poor. The battery cover plate assembly in this embodiment can reliably solve the defects of the above-mentioned structural form.

[0045] In a possible implementation, the through hole 103 includes a first hole section 1031 and a second hole section 1032 arranged in sequence from top to bottom. The aperture of the second hole section 1032 is larger than that of the first hole section 1031. The stepped surface where the second hole section 1032 is connected to the first hole section 1031 forms a riveting surface 1033. The riveting platform 203 is respectively riveted and matched with the riveting surface 1033 and the inner wall of the second hole section 1032. This kind of riveting form has a larger contact surface at the matching position, and the connection strength and reliability after subsequent welding connection are also higher. In addition, the riveting platform 203 is located in the second hole section 1032, which can improve the flatness of the peripheral surface of the riveting platform 203 and the second hole section 1032.

[0046] It can be understood that as an alternative implementation, the through hole 103 can also be a through hole with a consistent inner diameter, and the riveting platform 203 is directly in contact and matched with the peripheral surface of the through hole 103.

[0047] In a possible implementation, the riveting surface 1033 is an annular surface. The width of the riveting surface 1033 along the radial direction is greater than or equal to 0.15 mm, and the length of the second hole section 1032 along the axial direction is greater than or equal to 0.35 mm. The second hole section 1032 with such specification dimensions can ensure the connection strength between the riveting platform 203 and the second hole section 1032, and at the same time, it can also ensure the reliability of the subsequent welding process.

[0048] In a possible implementation, the top of the pole connection part 101 has a convex platform 1012 protruding upward. At the position corresponding to the convex platform 1012 at the bottom of the pole connection part 101, a groove 1013 is formed upward. The top surface of the convex platform 1012 forms a first mating surface 1011. The through hole 103 is located in the convex platform 1012 and communicates with the groove 1013. The top surface of the groove 1013 is recessed upward around the position of the through hole 103 to form a welding groove 1014. The pole 2 and the pole connection part 101 are connected by penetration welding at the position of the welding groove 1014. While further improving the connection strength, the welding groove 1014 can also accommodate the solder joints generated at this place, improve the flatness of the top surface of the groove 1013, and avoid the solder joints protruding downward and interfering with other components.

[0049] Among them, the specific shapes of the first mating surface 1011 and the second mating surface 201 are not limited, and can be circular, square, etc., as long as it is convenient for manufacturing; in addition, the specific specification dimensions of the convex platform 1012, the groove 1013, etc. are not strictly limited, and can be flexibly selected and adjusted according to the specification dimensions of the battery cell assembly.

[0050] In a possible implementation, the welding groove 1014 is an annular groove, the through hole 103 is a circular hole, the welding groove 1014 is arranged on the side wall close to the groove 1013, and the distance from the inner side wall of the welding groove 1014 along the radial direction to the inner wall of the through hole 103 is greater than or equal to 1.2 mm. After welding in the welding groove 1014 of this form, the stress uniformity is better and the connection is more stable and reliable. It can prevent the stress concentration phenomenon at the local position of the wall surface. In addition, for the welding groove 1014 of this size, it can prevent the welding width at the welding groove 1014 from overlapping with the welding width at the position of the through hole 103, and can reduce the risk of gas holes, welding slag, etc.

[0051] Specifically, as Figure 4 shown, the dimension represented by W is the distance from the inner side wall of the welding groove 1014 along the radial direction to the inner wall of the through hole 103.

[0052] Furthermore, the distance from the inner side wall of the welding groove 1014 along the radial direction to the inner wall of the through hole 103 being greater than or equal to 1.2 mm can also improve the safety and reliability during welding at the position of the welding groove 1014, and prevent the heat transfer during welding from melting other surrounding components at the wall surface.

[0053] In a possible implementation, it further includes a first insulating member 4 arranged between the connecting piece 1 and the cover plate 3. The welding groove 1014 is an annular groove, the boss 1012 is a frustum, and the distance from the outer side wall of the welding groove 1014 along the radial direction to the side wall of the boss 1012 is greater than or equal to 0.8 mm. Such a specification size can improve the safety and reliability during welding at the position of the welding groove 1014 while meeting the connection strength requirements, and prevent the heat transfer during welding from melting other surrounding components at the wall surface.

[0054] Specifically, as Figure 4 shown, the dimension represented by L is the distance from the outer side wall of the welding groove 1014 along the radial direction to the side wall of the boss 1012.

[0055] Furthermore, the battery cell cover plate assembly further includes a second insulating member 5 arranged between the assembly hole and the pole column 2. The pole column 2 includes a first column section, a second column section, and a third column section from top to bottom. The diameters of the first column section, the second column section, and the third column section decrease in sequence. The third column section is the connecting column 202. The first column section and the second column section form a stepped surface. The first column section forms a limiting rib for positioning and cooperating with the cover plate 3. The bottom surface of the first column section cooperates with the top surface of the cover plate 3 through the second insulating member 5, and the side wall of the second column section cooperates with the inner wall of the assembly hole through the second insulating member 5.

[0056] Among them, the pole connection part 101 is arranged higher than the tab connection part 102, and at least one step surface is formed at the connection part between the pole connection part 101 and the tab connection part 102. The shape of the first insulating member 4 corresponds to and matches the shape of this step surface.

[0057] In a possible implementation manner, the depth of the welding groove 1014 is greater than or equal to 0.2 mm, which can prevent the solder joint at this place from protruding downward from the top surface of the groove 1013, and improve the flatness of this local position.

[0058] In a possible implementation manner, a groove 1013 is formed at one end of the tab connection part 102 away from the pole connection part 101 along the direction close to the pole connection part 101. Connection surfaces 1021 are respectively formed on the top surfaces of the tab connection part 102 on both sides of the groove 1013. The tab connection part 102 in this form is lighter in weight, so that one tab connection part 102 can be connected to two tabs 601 at the same time, and the structural form is simple and reliable.

[0059] It can be understood that as an alternative implementation manner, the tab connection part 102 can also be an integral structure, and no through groove 1022 is provided thereon.

[0060] In a possible implementation manner, the cover plate 3 includes a main body plate 301 and an assembly plate 302. The main body plate 301 is assembled and connected to the pole 2. A welding hole 3011 corresponding to the tab connection part 102 is formed in the main body plate 301. The assembly plate 302 matches the shape of the welding hole 3011 and is assembled in the welding hole 3011. After the cell cover plate assembly is installed, the tab 601 and the tab connection part 102 can be directly welded through the welding hole 3011, which can effectively simplify the assembly steps and improve the production efficiency.

[0061] Specifically, the assembly plate 302 includes a sealing plate 3021 and an insulating plate 3022 connected in sequence from top to bottom. The sealing plate 3021 is used for assembling and connecting with the cover plate 3, and the insulating plate 3022 can effectively improve the insulation reliability between the sealing plate 3021 and the internal components.

[0062] In a possible implementation manner, the number of the connection pieces 1 and the poles 2 is two each and they are respectively arranged corresponding to the positive and negative electrodes of the cell 6. The cover plate 3 is correspondingly provided with a welding hole 3011. One welding hole 3011 simultaneously covers the areas corresponding to the two tab connection parts 102. In this form of cover plate 3, only one welding hole 3011 needs to be opened to complete the assembly connection process of the two tabs 601, and only a single connection process of the assembly plate 302 is needed for subsequent plugging, and the assembly steps are fewer.

[0063] It can be understood that as an alternative implementation manner, the welding holes 3011 on the cover plate 3 can also be two, corresponding to the two tab connection parts 102.

[0064] Specifically, as Figure 2 shown, there are no restrictions on the specific composition and material of the pole post 2 of the positive electrode and the pole post 2 of the negative electrode, and they can be selected according to the structures of the actual pole post 2 of the positive electrode and the pole post 2 of the negative electrode.

[0065] According to an embodiment of the present invention, on the other hand, a battery cell assembly is provided, which includes: the above-mentioned battery cell cover assembly and the battery cell 6. A tab 601 is provided on the top of the battery cell 6. The tab 601 includes a connecting section and a bending section. The connecting section is located on one side of the tab connecting portion 102 of the battery cell cover assembly. The bending section is connected to the top of the connecting section and extends along the top surface of the tab connecting portion 102. The tab 601 is welded to the tab connecting portion 102.

[0066] Specifically, the tab 601 and the tab connecting portion 102 are welded by welding processes such as laser welding or ultrasonic welding to achieve electrical connection.

[0067] According to an embodiment of the present invention, on the other hand, a battery cell assembly is provided, which includes: the above-mentioned battery cell cover assembly and the battery cell 6. A tab 601 is provided on the top of the battery cell 6. The tab 601 includes a connecting section and a bending section. The connecting section is located on one side of the tab connecting portion 102 of the battery cell cover assembly. The bending section is connected to the top of the connecting section and extends along the top surface of the tab connecting portion 102. The tab 601 is welded to the tab connecting portion 102.

[0068] Specifically, the tab 601 and the tab connecting portion 102 are welded by welding processes such as laser welding or ultrasonic welding to achieve electrical connection.

[0069] In a possible implementation manner, two tabs 601 are respectively provided on the positive electrode and the negative electrode of the battery cell 6. The two tabs 601 of the same pole are oppositely arranged on both sides of the corresponding tab connecting portion 102, and the bending sections of the two tabs 601 are welded to the same tab connecting portion 102.

[0070] In a possible implementation manner, the battery cell assembly further includes a housing 7. The housing 7 has a receiving groove with an upward opening. The battery cell 6 is disposed in the receiving groove, and the battery cell cover assembly is disposed on the top of the housing 7 to block the opening.

[0071] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cover assembly, characterized in that: include: A connecting piece, comprising a pole connecting portion and a pole lug connecting portion connected in sequence, wherein the top surface of the pole lug connecting portion forms a connecting surface for connecting with the pole lug, and the top surface of the pole connecting portion forms a first mating surface, wherein a vertically extending through hole is provided on the first mating surface; A pole, a second mating surface formed at the bottom thereof and mating with the first mating surface, a connecting column plug-matched with the through hole is provided at the position of the pole located at the second mating surface, the pole is welded and connected to the through hole of the connecting sheet through the connecting column, a riveted section is formed at the lower end of the connecting column and passes through the through hole, and the riveted section forms a riveted platform mating with the peripheral surface of the through hole; The cover plate is located on the upper side of the connecting piece and has an assembly hole for the pole to pass through.

2. The battery cover assembly according to claim 1, characterized in that: The through hole includes a first hole segment and a second hole segment arranged in sequence from top to bottom, the aperture of the second hole segment is larger than the aperture of the first hole segment, the step surface connecting the second hole segment and the first hole segment forms a riveted surface, and the riveting platform is riveted to the riveted surface and the inner wall of the second hole segment respectively.

3. The battery cover assembly according to claim 2, characterized in that: The riveted surface is an annular surface, the width of the riveted surface along the radial direction is greater than or equal to 0.15 mm, and / or the length of the second hole segment along the axial direction is greater than or equal to 0.35 mm.

4. The battery cell cover plate assembly according to any one of claims 1 to 3, characterized in that: The top of the pole connecting part has an upwardly protruding boss, and the bottom of the pole connecting part forms a groove upwardly corresponding to the position of the boss, the top surface of the boss forms the first mating surface, the through hole is located on the boss and connected to the groove, and the top surface of the groove is concave upward around the position of the through hole to form a welding groove.

5. The battery cover assembly according to claim 4, characterized in that: The welding groove is an annular groove, the through hole is a circular hole, the welding groove is arranged close to the side wall of the groove, and the distance from the inner side wall of the welding groove to the inner wall of the through hole along the radial direction is greater than or equal to 1.2 mm.

6. The battery cover assembly according to claim 4, characterized in that: It also includes a first insulating member arranged between the connecting plate and the cover plate, the welding groove is an annular groove, the boss is a truncated cone, and the distance from the outer wall of the welding groove to the side wall of the boss along the radial direction is greater than or equal to 0.8 mm.

7. The battery cover assembly according to claim 4, characterized in that: The depth of the welding groove is greater than or equal to 0.2 mm.

8. The battery cell cover plate assembly according to any one of claims 1 to 3, characterized in that: One end of the pole lug connection portion away from the pole post connection portion forms a groove along a direction close to the pole post connection portion, and the top surfaces of the pole lug connection portion located on both sides of the groove form connection surfaces respectively.

9. The battery cell cover plate assembly according to any one of claims 1 to 3, characterized in that: The cover plate includes a main body plate and an assembly plate. The main body plate is assembled and connected to the pole. The main body plate is provided with a welding hole corresponding to the pole ear connection portion. The assembly plate matches the shape of the welding hole and is assembled in the welding hole.

10. A battery cell assembly, characterized in that: include: The battery cell cover assembly according to any one of claims 1 to 9; A battery cell is provided with a pole lug on the top, the pole lug includes a connecting section and a bending section, the connecting section is located on one side of the pole lug connecting portion of the battery cell cover assembly, the bending section is connected to the top of the connecting section and extends along the top surface of the pole lug connecting portion, and the pole lug is welded to the pole lug connecting portion.

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