Battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises a cover plate assembly and a pole group. The cover plate assembly comprises a pole and a cover plate body; the pole comprises a pole bottom plate and at least two pole bodies arranged on the pole bottom plate, and the pole bodies and the pole bottom plate are integrally connected; the cover plate body is provided with first pole mounting holes with the number corresponding to that of the pole bodies, the pole bottom plate is arranged on the first surface of the cover plate body, and the pole bodies are arranged in the first pole mounting holes; the pole group is provided with a pole lug, a plurality of layers of foils of the pole lug are connected into a whole through ultrasonic welding, the pole lug is connected with the pole bottom plate through laser welding, and the laser welding is located in the ultrasonic welding; in the X direction, the distance between the laser welding mark and the side edge of the pole bottom plate is L1, the length of the laser welding mark is increased to delta L, and L1 and delta L meet preset conditions. According to the invention, the welding area between the pole lug and the pole bottom plate can be increased, the overcurrent capability is improved, and the fast-charging high-current requirement is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery, in particular to a battery cell and a battery pack. BACKGROUND

[0002] In recent years, with the rapid development of new energy vehicles and energy storage technology, lithium ion batteries have become the mainstream power battery selection due to their high energy density, long cycle life and environmental protection characteristics. In order to shorten the charging time, fast charging technology has become the focus of industry research, which puts forward higher requirements for the overcurrent capacity, heat dissipation performance and structural reliability of the battery.

[0003] In the design of the battery cell structure, the traditional riveting cover plate usually uses a single pole or two independent poles to realize current transmission. However, with the increase of fast charging current, the cross-sectional area of a single pole is limited, and the overcurrent capacity is limited; although the double-pole design can be divided, the separate poles will weaken the structural strength, and the uneven current distribution will further reduce the overcurrent capacity, and the welding area of the pole bottom plate and the tab of the double-pole is limited, which is difficult to meet the demand of high-power fast charging.

[0004] Therefore, how to improve the overcurrent capacity of the pole under the premise of ensuring the structural strength has become a key problem to be solved in the current lithium ion battery fast charging technology. SUMMARY

[0005] Therefore, the present application provides a battery cell and a battery pack to solve the problem of poor overcurrent capacity of the pole.

[0006] In a first aspect, the present application provides a battery cell, comprising a cover plate assembly and a pole group. The cover plate assembly comprises a pole and a cover plate body; the pole comprises a pole bottom plate and at least two pole bodies provided on the pole bottom plate, the pole body and the pole bottom plate are integrally connected; the cover plate body has a first surface and a second surface arranged oppositely, the cover plate body is provided with a first pole mounting hole corresponding in number to the pole body, the first pole mounting hole penetrates through the first surface and the second surface of the cover plate body, the pole bottom plate is arranged on the first surface of the cover plate body, and the pole body is arranged in the first pole mounting hole; the pole group is provided with a tab, the tab comprises a plurality of layers of foil, the plurality of layers of foil are connected into one body by ultrasonic welding, the tab is connected with the pole bottom plate by laser welding, and the laser welding is located within the range of the ultrasonic welding. In the X direction, the side edge of the laser welding to the pole bottom plate is L1, in mm, The length of the laser welding increases by ΔL, in mm, The width of the laser welding is W, in mm, The overcurrent area of the laser welding increases by S, in mm 2 , The overcurrent capacity of the unit cross-sectional area of the laser welding is J, in A / mm 2 , The laser welding imprint increases the current-carrying capacity I, which is in A, Satisfies: S = AL x W, I = J x S, 2mm≤L1≤6.5mm, ΔL≥4mm.

[0007] Beneficial effects: The battery cell provided by the application integrates two or more pole posts in a traditional split type, that is, two or more pole post bodies are arranged on a pole post bottom plate, and the pole post bottom plate and the pole post body are integrally connected. The pole post bottom plate can provide a larger area for welding with the tab, thereby significantly increasing the welding area and improving the overcurrent capacity to meet the fast charging high current demand.

[0008] Moreover, the pole post body and the pole post bottom plate are integrally connected, which can reduce the contact resistance and improve the conductivity efficiency. At the same time, the design of multiple pole post bodies can achieve higher current carrying capacity in limited space. The pole post body and the pole post bottom plate are integrally connected, which avoids the problem of weakened pole post structural strength caused by traditional split double pole posts, and improves the structural strength of the pole post.

[0009] Finally, the embodiment of the application also limits the side distance L1 of the laser welding imprint to the pole post bottom plate along the X direction, which is not less than 2mm, otherwise, it is difficult for the tab to be pressed, and the welding yield between the tab and the pole post bottom plate is low.

[0010] The application can increase the length of the laser welding imprint by designing two or more pole posts in the related art as an integrated structure, so that AL is at least 4mm.

[0011] In an optional embodiment, the side distance of the laser welding imprint to the ultrasonic welding imprint along the X direction is L2, which is in mm, the side distance of the laser welding imprint to the pole post bottom plate along the Y direction is L3, which is in mm, and the side distance of the laser welding imprint to the ultrasonic welding imprint along the Y direction is L4, which is in mm, and satisfies: 1.5mm≤L2≤5mm, 2mm≤L3≤4.5mm, 1.5mm≤L4≤4mm.

[0012] In an optional embodiment, the ultrasonic welding imprint is a continuous line along the X direction; or, the ultrasonic welding imprint is multiple lines along the X direction, and adjacent ultrasonic welding imprints have an overlapping area.

[0013] In an optional embodiment, the laser welding imprint is a continuous line along the X direction; or, the laser welding imprint is multiple lines along the X direction, and adjacent laser welding imprints have an overlapping area.

[0014] In an alternative embodiment, the cross-sectional shape of the pole column along the X-Y plane is circular; or, the cross-sectional shape of the pole column along the X-Y plane is a track shape, including two oppositely arranged straight edge segments and an arc segment connecting the two straight edge segments, and the straight edge segments are arranged along the X direction.

[0015] In an alternative embodiment, the material of the pole column is pure copper or pure aluminum.

[0016] In an alternative embodiment, the pole column bottom plate includes a bottom plate main body and a bottom plate column segment protruding from the bottom plate main body, the pole column body is integrally connected with the bottom plate column segment, the pole column bottom plate is made of copper material, and the pole column body is made of aluminum material.

[0017] In an alternative embodiment, the cover plate assembly further includes a riveting block, a first insulating piece, and a second insulating piece. The riveting block is provided with a corresponding number of second pole column mounting holes corresponding to the pole column body; the riveting block is arranged on the second surface of the cover plate body; the first insulating piece is provided with a corresponding number of third pole column mounting holes corresponding to the pole column body; the first insulating piece is arranged between the riveting block and the second surface of the cover plate body, and the riveting block and the cover plate body are insulatively connected; the second insulating piece is provided with a corresponding number of fourth pole column mounting holes corresponding to the pole column body; the second insulating piece is arranged between the first surface of the cover plate body and the pole column bottom plate, and the cover plate body and the pole column bottom plate are insulatively connected; the pole column body passes through the fourth pole column mounting hole, the first pole column mounting hole, the third pole column mounting hole, and the second pole column mounting hole in sequence, and is riveted or welded with the riveting block.

[0018] In an alternative embodiment, a shell is further included. The shell has a receiving cavity, and the shell is provided with at least one open end communicating with the receiving cavity; the pole group is arranged in the receiving cavity, and the pole group has a positive electrode lug and a negative electrode lug; the cover plate assembly is arranged at the open end of the shell, and the pole group is encapsulated in the shell; the pole column includes a positive pole column and a negative pole column, and the positive pole column is welded with the positive electrode lug, and the negative pole column is welded with the negative electrode lug.

[0019] In a second aspect, the application further provides a battery pack including a plurality of the battery cells in the above technical solutions, and the battery cells are electrically connected.

[0020] Beneficial effects: Because the battery pack includes the battery cells, it has all the technical effects of the battery cells, which are not described here. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0022] Figure 1 This is a schematic diagram of the structure of two independent poles in the related technology; Figure 2 This is a schematic diagram of the structure of the electrode post in a battery cell according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the electrode structure in another battery cell according to an embodiment of the present invention; Figure 4 This is a cross-sectional view of an electrode post in a battery cell according to an embodiment of the present invention; Figure 5 This is a cross-sectional view of the terminal post in another battery cell according to an embodiment of the present invention; Figure 6 This is a schematic diagram showing the dimensions of the welding of two independent terminals and tabs to a battery cell in a related technology. Figure 7 This is a schematic diagram of the dimensions of the electrode post and electrode tab welding in a battery cell according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the solder mark structure in another battery cell according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the structure of a cover plate assembly for a battery cell according to an embodiment of the present invention; Figure 10 for Figure 9 Top view of the cover plate assembly shown; Figure 11 For along Figure 10 Sectional view at point AA; Figure 12 For along Figure 10 Sectional view at point BB; Figure 13 for Figure 9 An exploded view of the cover plate assembly shown; Figure 14 This is a cross-sectional view of a cover plate assembly for a battery cell according to another embodiment of the present invention; Figure 15 This is a schematic diagram illustrating the dimensional requirements for welding two independent terminals and tabs to a battery cell in a related technology. Figure 16 This is a schematic diagram illustrating the dimensional requirements for welding the electrode post and electrode tab in a battery cell according to an embodiment of the present invention.

[0023] Figure 1 , Figure 6 and Figure 15 Explanation of reference numerals in the attached figures: 1', pole post; 101', pole post base plate; 102', pole post body; 3', pole group; 301', pole tab; 4', ultrasonic welding stamp; 5', laser welding stamp.

[0024] Other annotations in the accompanying drawings: 1, pole post; 101, pole post base plate; 1011, base plate main body; 1012, base plate post section; 102, pole post body; 1021, assembly post section; 1022, riveting post section; 2, cover plate body; 201, first pole post mounting hole; 3, pole group; 301, pole lug; 4, ultrasonic welding mark; 5, laser welding mark; 6, riveting block; 601, second pole post mounting hole; 7, first insulating piece; 701, third pole post mounting hole; 8, second insulating piece; 801, fourth pole post mounting hole; 9, sealing ring; 10, copper pressing nozzle. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0026] The embodiments of the present application are described below with reference to the drawings. Figures 1 to 16

[0027] According to the embodiments of the present application, in a first aspect, an electric core is provided, which comprises a cover plate assembly and a pole group 3. The cover plate assembly comprises a pole post 1 and a cover plate body 2; the pole post 1 comprises a pole post base plate 101 and at least two pole post bodies 102 arranged on the pole post base plate 101, and the pole post bodies 102 are integrally connected with the pole post base plate 101; the cover plate body 2 has a first surface and a second surface arranged oppositely, and the cover plate body 2 is provided with a corresponding number of first pole post mounting holes 201 corresponding to the pole post bodies 102, the first pole post mounting holes 201 penetrating through the first surface and the second surface of the cover plate body 2, the pole post base plate 101 is arranged on the first surface of the cover plate body 2, and the pole post bodies 102 are arranged in the first pole post mounting holes 201; the pole group 3 is provided with a pole lug 301, the pole lug 301 comprises a plurality of layers of foils, the plurality of layers of foils are connected into one body through ultrasonic welding marks 4, the pole lug 301 is connected with the pole post base plate 101 through laser welding marks 5, and the laser welding marks 5 are located within the range of the ultrasonic welding marks 4; In the X direction, the distance from the laser welding mark 5 to the side edge of the pole post base plate 101 is L1, and the unit is mm, The length of the laser welding mark 5 is increased by ΔL, and the unit is mm, The width of the laser welding mark 5 is W, and the unit is mm, The increased flow area of the laser welding mark 5 is S, and the unit is mm 2 , The flow capacity per unit cross-sectional area of the laser welding mark 5 is J, and the unit is A / mm 2 , The increased current-carrying capacity of the laser welding mark 5 is I, and the unit is A,​ Satisfies: S = AL x W, I = J x S, 2mm≤L1≤6.5mm, ΔL≥4mm.

[0028] Specifically, in the views shown in Figure 11 and Figure 12 , the first surface of the cover plate body 2 is its lower surface, and the second surface of the cover plate body 2 is its upper surface. In the cell structure, the first surface of the cover plate body 2 is the surface close to the pole group 3, and the second surface of the cover plate body 2 is the surface away from the pole group 3.

[0029] In Figure 6 and Figure 7 , the X direction is the length direction of the cover plate body 2 or the pole post bottom plate 101, and the Y direction is the width direction of the cover plate body 2 or the pole post bottom plate 101.

[0030] In some related technologies, in order to improve the overcurrent capacity, a split type independent pole post 1' is adopted, taking two as an example, referring to Figure 1 , two independent pole posts 1' are arranged in one cell cover plate assembly, and each pole post 1' includes a pole post bottom plate 101' and a pole post body 102'. After assembly, the pole post bottom plates 101' of the two pole posts 1' are both welded with the tab 301' of the pole group 3', and the ultrasonic welding mark 4' and the laser welding mark 5' are shown in Figure 6 .

[0031] Specifically, the tab 301' of the pole group 3' is stacked by multiple layers of foil, and the multiple layers of foil are connected into one body by ultrasonic welding. Two pole posts 1' are respectively referred to as a first pole post and a second pole post. In Figure 6 , along the X direction, the length of the pole post bottom plate 101' of the first pole post is A, unit: mm, the length of the pole post bottom plate 101' of the second pole post is B, unit: mm, the maximum side distance between the two pole post bottom plates 101' is E, unit: mm, the first pole post is connected with the tab 301' through the first laser welding mark, and the second pole post is connected with the tab 301' through the second laser welding mark. The distance from the right end of the first laser welding mark to the right end of the pole post bottom plate 101' of the first pole post is L1, the distance from the left end of the second laser welding mark to the left end of the pole post bottom plate 101' of the second pole post is L1, L1≥2mm, and the distance between the first laser welding mark and the second laser welding mark is D, unit: mm.

[0032] In the cell provided by the application, the pole post 1 adopts an integrated structure and also includes a pole post bottom plate 101 and a pole post body 102, but the pole post bottom plate 101 is only provided with one, and two or more pole post bodies 102 are arranged on the same pole post bottom plate 101. Also taking two as an example, referring toFigures 2 to 5 After assembly, the pole base plate 101 of the pole 1 and the pole lug 301 of the pole group 3 are welded, and the welding marks are referred to Figure 7 or Figure 8 .

[0033] Specifically, in the present application, an integrated pole 1 is adopted, and there are two size design schemes as follows.

[0034] Scheme one, referring to Figure 7 , along the X direction, compared with the scheme shown in Figure 6 , the total size occupied by the pole base plate 101 of the pole 1 remains unchanged, that is, in this scheme, the length of the pole base plate 101 of the pole 1 is L, L=E>A+B, so that the structure in the original cover plate body 2 and other components, such as the position of the pole 1 mounting hole, is not changed. In this scheme, only the distance L1≥2mm between the two sides of the laser welding mark 5 and the two sides of the pole base plate 101 needs to be ensured, and the remaining length can be arranged for the laser welding mark 5, and compared with the related art of Figure 6 , the length of the laser welding mark 5 in this scheme increases by ΔL, ΔL=D, and D≥4mm.

[0035] Scheme two, referring to Figure 8 , along the X direction, compared with the scheme shown in Figure 6 , the length of the pole base plate 101 itself remains unchanged, that is, in this scheme, the length of the pole base plate 101 of the pole 1 is L, L=A+B, and in this scheme, only the distance L1≥2mm between the two sides of the laser welding mark 5 and the two sides of the pole base plate 101 needs to be ensured, and the remaining length can be arranged for the laser welding mark 5, and compared with the related art of Figure 6 , the length of the laser welding mark 5 in this scheme increases by ΔL, ΔL≥4mm.

[0036] For scheme two, not only can the area of the laser welding mark 5 be increased to improve the flow capacity, but also at least 4mm of the length of the pole lug 301 can be saved to achieve weight reduction and cost reduction under the condition that the flow capacity of the pole lug 301 itself is sufficient.

[0037] For the present application, the length of the laser welding mark 5 can be increased, and L1≥2mm, ΔL≥4mm, which will be described in detail below.

[0038] In the related art of the split pole scheme, taking two poles as an example, referring to Figure 15, when the pole post bottom plate is welded with the pole lug, the pole post bottom plate and the pole lug need to be fixed by a welding tool, for example, a copper pressing nozzle 10 is used as the welding tool. The wall thickness t of the copper pressing nozzle 10 is usually 1 mm to 2 mm, and the copper pressing nozzle 10 needs to occupy the size of the pole post bottom plate along the X direction, that is, the wall thickness t of the copper pressing nozzle 10. In order to increase the welding area and improve the overcurrent capacity, the thinner the wall thickness of the copper pressing nozzle 10 is, the better, that is, preferably 1 mm. When laser welding, the starting point is close to the copper pressing nozzle 10, which is easy to burn the copper pressing nozzle 10 and affect the service life of the copper pressing nozzle 10, so a safety distance a between the starting point of laser welding and the copper pressing nozzle 10 needs to be reserved, a is mm, a≥1 mm, so the edge of the laser welding is away from the single side of the pole post bottom plate by a distance L1, L1 is at least 2 mm, and the distance L1 needs to be ensured at both ends of each pole. Therefore, for the split double-pole scheme, at least 4×L1 of blank length needs to be reserved. The two or more pole post bottom plates are designed as an integrated structure, and at least two pole bodies 102 are taken as an example. Only L1 of blank length needs to be reserved at both ends of the pole post bottom plate, as shown in Figure 16 , a total of 2×L1 of blank length is reserved, and correspondingly, the length ΔL of the increased laser welding is greater than or equal to 2×L1, that is, ΔL≥4 mm.

[0039] When the width of the laser welding 5 is W, the overcurrent area S of the laser welding 5 is ΔL×W.

[0040] The overcurrent capacity of the unit cross-sectional area of the laser welding 5 is J, and the unit is A / mm 2 , that is, each square millimeter can pass through J amperes of current.

[0041] The carrying capacity of the laser welding 5 is I, and the unit is A, that is, the maximum current that the laser welding can safely bear. I=J×S=J×ΔL×W.

[0042] Therefore, the battery cell provided by the present application, in which the pole 1 is integrally arranged with two or more pole bodies 102 on the pole post bottom plate 101, that is, the pole post bottom plate 101 and the pole body are integrally connected, the pole post bottom plate 101 can provide a larger area for welding with the pole lug 301, thereby significantly increasing the welding area and improving the overcurrent capacity of the pole lug after welding with the pole, thereby meeting the fast charging high current demand.

[0043] Furthermore, the pole body 102 is integrally connected with the pole post bottom plate 101, which can reduce the contact resistance and improve the conductivity. At the same time, the design of multiple pole bodies 102 can also realize higher current carrying capacity in limited space. The pole body 102 is integrally connected with the pole post bottom plate 101, which avoids the problem that the structural strength of the pole 1 is weakened due to the split of the traditional double-pole, and improves the structural strength of the pole 1.

[0044] Finally, the embodiment of the present application also limits the side distance L1 between the laser welding 5 and the pole plate 101 in the X direction to be no less than 2 mm, otherwise, the tab 301 is difficult to press, and the welding yield between the tab 301 and the pole plate 101 is low. L1 is no more than 6.5 mm, otherwise, the area of the laser welding 5 is greatly affected, and the overcurrent capacity is affected.

[0045] The present application can increase the length of the laser welding 5 by designing two or more pole plates 1 in the related art as an integrated structure, so that ΔL is at least 4 mm.

[0046] In some embodiments, the side distance L2 between the laser welding 5 and the ultrasonic welding 4 in the X direction is in mm, the side distance L3 between the laser welding 5 and the pole plate 101 in the Y direction is in mm, and the side distance L4 between the laser welding 5 and the ultrasonic welding 4 in the Y direction is in mm, which satisfies: 1.5 mm≤L2≤5 mm, 2 mm≤L3≤4.5 mm, 1.5 mm≤L4≤4 mm.

[0047] Specifically, referring to Figure 7 , the side distance L2 between the laser welding 5 and the ultrasonic welding 4 in the X direction and the side distance L4 between the laser welding 5 and the ultrasonic welding 4 in the Y direction are both greater than or equal to 1.5 mm, otherwise, it will be difficult to laser weld, and it is easy to hit the copper pressure nozzle 10 during welding. It should be noted that there are two side distances L2 in the X direction, and the two side distances L2 can be equal or not equal, but both satisfy the requirement of at least 1.5 mm. Similarly, there are two side distances L4 in the X direction, and the two side distances L4 can be equal or not equal, but both satisfy the requirement of at least 1.5 mm.

[0048] Continuing to refer to Figure 7 , the side distance L3 between the laser welding 5 and the pole plate 101 in the Y direction is at least 2 mm, the tab 301 is difficult to press, and the welding yield between the tab 301 and the pole plate 101 is low. It should be noted that there are two side distances L3 in the Y direction, and the two side distances L3 can be equal or not equal, but both satisfy the requirement of at least 2 mm.

[0049] According to the positional relationship between the ultrasonic welding 4 and the pole plate 101, two schemes are provided: Scheme one, the edges of the ultrasonic welding are flush with the two side edges of the pole plate, or the edges of the ultrasonic welding exceed the two side edges of the pole plate in the X direction.

[0050] Scheme two, the edges of the ultrasonic welding are located inside the two side edges of the pole plate. Figure 16In the process, the edge of the ultrasonic weld mark extends beyond the two side edges of the electrode base plate. Figure 7 and Figure 8 In the process, the edge of the ultrasonic weld mark is located inside the two sides of the electrode base plate.

[0051] For Scheme 2, the requirement is 2mm≤L1≤5mm.

[0052] To verify the technical effects of the present invention, specific experimental cases are provided according to the two schemes described above, as detailed in Table 1 and Table 2.

[0053] Table 1

[0054] Table 2

[0055] Therefore, by controlling L1, L2, L3, and L4 within the above-mentioned value ranges, it is possible to improve the current carrying capacity after welding the tabs and posts while ensuring a welding yield of ≥99%.

[0056] In some embodiments, the ultrasonic weld mark 4 is a continuous line along the X direction; or, the ultrasonic weld mark 4 is multiple lines along the X direction, and adjacent ultrasonic weld marks 4 have overlapping areas.

[0057] Specifically, such as Figure 7 As shown, the ultrasonic welding stamp 4 can be set as a continuous single line; or it can be set as multiple lines, such as... Figure 8 As shown, however, to ensure the connection strength of the tab 301, when multiple ultrasonic weld marks 4 are set, there is an overlap area between adjacent ultrasonic weld marks 4. Figure 8 In the diagram, K1 refers to the overlapping area of ​​ultrasonic welding stamp 4.

[0058] In some embodiments, the laser weld mark 5 is a continuous line along the X direction; or, the laser weld mark 5 is multiple lines along the X direction, and adjacent laser weld marks 5 have overlapping areas.

[0059] Specifically, such as Figure 7 As shown, the laser welding mark 5 can be set to a continuous line; or it can be set to multiple lines, such as... Figure 8 As shown, however, to ensure the connection strength between the tab 301 and the base plate 101, when multiple laser weld lines 5 are provided, there is an overlap area between adjacent laser weld lines 5. Figure 8 In the diagram, K2 refers to the overlapping area of ​​laser soldering mark 5.

[0060] In some embodiments, the cross section of the pole post body 102 along the X-Y plane is circular; or, the cross section of the pole post body 102 along the X-Y plane is track-shaped, including two opposite straight edge segments and an arc segment connecting the two straight edge segments, the straight edge segments being arranged along the X direction.

[0061] The electric cell provided by the present application is suitable for both circular pole posts and track-shaped pole posts. Specifically, the structure of the circular pole post is shown in Figure 2 , and the cross section of the pole post body 102 along the X-Y plane is circular. The structure of the track-shaped pole post is shown in Figure 3 , and the cross section of the pole post body 102 along the X-Y plane is track-shaped. The two ends along the X direction are arc segments, and the two ends along the Y direction are straight edge segments.

[0062] There are two connection methods between the pole post 1 and the cover plate body 2, one is riveting, and the other is welding.

[0063] For the riveting scheme, the shape of the pole post body 102 of the pole post 1 will change before and after riveting. Before riveting, the structure of the pole post body 102 of the pole post 1 is shown in Figure 4 , and the pole post body 102 includes an assembly column segment 1021 connected with the pole post bottom plate 101 and a riveting column segment 1022 arranged at the upper part of the assembly column segment 1021. The assembly column segment 1021 is used for fitting with the first pole post mounting hole 201 of the cover plate during assembly, and the riveting column segment 1022 is used for riveting with the riveting block 6 during assembly. After riveting, the structure of the riveting column segment 1022 is deformed by material bulging, and the pole post 1 shown in Figure 5 is obtained. The structure of the cover plate assembly for the riveting scheme is shown in Figures 9 to 13 .

[0064] For the welding scheme, the structure of the pole post body 102 of the pole post 1 is shown in Figure 4 , and the structure of the cover plate assembly after welding is shown in Figure 14 .

[0065] In some embodiments, the material of the pole post 1 is pure copper or pure aluminum.

[0066] In the present application, the pole post 1 adopts an integrated structure, which is suitable for both positive pole posts and negative pole posts. When the material of the pole post 1 is pure copper, the pole post 1 is a negative pole post, which is used for welding with a negative tab. When the material of the pole post 1 is pure aluminum, the pole post 1 is a positive pole post, which is used for welding with a positive tab.

[0067] In some embodiments, the pole post bottom plate 101 includes a bottom plate body 1011 and a bottom plate column segment 1012 protruding from the bottom plate body 1011, the pole post body 102 is integrally connected with the bottom plate column segment 1012, the pole post bottom plate 101 is made of copper material, and the pole post body 102 is made of aluminum material.

[0068] In some embodiments, the negative pole post is a copper-aluminum composite pole post. Referring to Figure 4 or Figure 5 The pole post bottom plate 101 (the bottom plate body 1011 and the bottom plate post segment 1012) is made of copper material, and the pole post body 102 is made of aluminum material. For the composite material pole post 1, the existing processing technology can be used to realize the integral molding structure, such as machining or cold heading.

[0069] In some embodiments, the cover plate assembly further includes a riveting block 6, a first insulating piece 7, and a second insulating piece 8. The riveting block 6 is provided with a corresponding number of second pole post mounting holes 601 corresponding to the pole post body 102; the riveting block 6 is arranged on the second surface of the cover plate body 2; the first insulating piece 7 is provided with a corresponding number of third pole post mounting holes 701 corresponding to the pole post body 102; the first insulating piece 7 is arranged between the riveting block 6 and the second surface of the cover plate body 2, and insulatively connects the riveting block 6 and the cover plate body 2; the second insulating piece 8 is provided with a corresponding number of fourth pole post mounting holes 801 corresponding to the pole post body 102; the second insulating piece 8 is arranged between the first surface of the cover plate body 2 and the pole post bottom plate 101, and insulatively connects the cover plate body 2 and the pole post bottom plate 101; the pole post body 102 sequentially passes through the fourth pole post mounting hole 801, the first pole post mounting hole 201, the third pole post mounting hole 701, and the second pole post mounting hole 601, and is riveted or welded with the riveting block 6.

[0070] The riveting block 6 can be used to fix the pole post 1 and provide mechanical support for the pole post 1. At the same time, since the riveting block 6 and the pole post 1 are in conductive connection, the riveting block 6 can serve as a conductive structure. For a square battery, the riveting block 6 can serve as an intermediate connecting piece between the pole post 1 and the module bus bar.

[0071] In the cell cover plate assembly, the riveting block 6 and the cover plate body 2 are usually made of metal material. The first insulating piece 7 arranged between the riveting block 6 and the cover plate body 2 can avoid direct contact between the two, enhance electrical insulation safety, and prevent short circuit risk.

[0072] Similarly, the pole post bottom plate 101 is also a conductive material. The second insulating piece 8 arranged between the pole post bottom plate 101 and the cover plate body 2 can block the conductive path between the pole post 1 and the cover plate body 2, and eliminate the short circuit risk caused by electrolyte leakage or metal chip residue.

[0073] In some embodiments, the first insulating piece 7 and the second insulating piece 8 are both plastic pieces.

[0074] In some embodiments, a sealing ring 9 is further included, the sealing ring 9 is sleeved on the pole post body 102 of the pole post 1, at least a part of the sealing ring 9 is located between the inner wall of the first pole post mounting hole 201 and the pole post body 102, and at least another part of the sealing ring 9 is located between the pole post bottom plate 101 and the cover plate body 2, so that the pole post 1 and the cover plate body 2 are sealingly connected.

[0075] In the embodiment, the sealing ring 9 is provided with at least two sealing sections, including an axial sealing section and a radial sealing section. At least a part of the sealing ring 9 is located between the inner wall of the first pole post mounting hole 201 and the pole post body 102, which is the axial sealing section, and the sealing ring 9 is compressed between the inner wall of the first pole post mounting hole 201 and the pole post body 102, so as to achieve axial sealing, fill the micro gap caused by the machining tolerance of the metal, and prevent the electrolyte from leaking along the side wall of the pole post 1. At least another part of the sealing ring 9 is located between the pole post bottom plate 101 and the cover plate body 2, which is the radial sealing section, and the sealing ring 9 extends between the pole post bottom plate 101 and the cover plate body 2 to form an end face compression seal, so as to achieve radial sealing and prevent electrolyte vapor from invading from the top.

[0076] In the embodiment, the sealing ring 9 achieves multi-stage sealing protection and completely blocks the leakage path.

[0077] Further, the sealing ring 9 is made of a material resistant to electrolyte corrosion to ensure the sealing effect and service life of the sealing ring 9. Further, the sealing ring 9 is made of an elastic material, such as fluorine rubber and silica gel, which can absorb the size deviation of the pole post 1 and the first pole post mounting hole 201.

[0078] In some embodiments, a shell is further included. The shell has a receiving cavity, and the shell is provided with at least one open end communicating with the receiving cavity; the pole group 3 is arranged in the receiving cavity, and the pole group 3 has a positive electrode lug and a negative electrode lug led out; the cover plate assembly is arranged at the open end of the shell to encapsulate the pole group 3 in the shell; the pole post 1 includes a positive pole post and a negative pole post, the positive pole post is welded with the positive electrode lug, and the negative pole post is welded with the negative electrode lug 301.

[0079] The cover plate assembly is used to close the opening of the battery cell shell, plays a role in sealing and protecting the internal components of the battery, prevents chemical leakage and the influence of the external environment on the battery. The pole post 1 provides a path for the inflow and outflow of current, ensuring the conduction of current during the charging and discharging process of the battery cell.

[0080] According to the embodiments of the present application, the second aspect further provides a battery pack including a plurality of battery cells in the above embodiments, and the battery cells are electrically connected.

[0081] Because the battery pack includes the battery cell, all the technical effects of the battery cell are possessed, which will not be repeated here.

[0082] While embodiments of the application have been described in connection with the preferred embodiments of the various figures, those of ordinary skill in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the application, and that such modifications and changes fall within the scope of the appended claims.

Claims

1. An electric cell, characterized by, The cover plate assembly comprises a pole post and a cover plate body; the pole post comprises a pole post bottom plate and at least two pole post columns arranged on the pole post bottom plate, the pole post columns and the pole post bottom plate are integrally connected; the cover plate body has a first surface and a second surface arranged oppositely, the cover plate body is provided with a number of first pole post mounting holes corresponding to the pole post columns, the first pole post mounting holes penetrate through the first surface and the second surface of the cover plate body, the pole post bottom plate is arranged on the first surface of the cover plate body, and the pole post columns are arranged in the first pole post mounting holes; The pole group is provided with a tab, the tab comprises a plurality of layers of foil, the plurality of layers of foil are integrally connected through ultrasonic welding marks, the tab is connected with the pole post bottom plate through laser welding marks, and the laser welding marks are located in the range of the ultrasonic welding marks; Along the X direction, the side distance of the laser welding mark to the pole post bottom plate is L1, and the unit is mm, Along the X direction, the length of the laser welding mark increases by ΔL, and the unit is mm, The width of the laser welding mark is W, and the unit is mm, The increased current-carrying capacity of the laser welding mark is I, and the unit is A, The laser welding imprint increased flow area is S, unit: mm 2 , The overcurrent capacity of the laser welding print per unit cross-sectional area is J, with the unit of A / mm 2 , Satisfies: S=ΔL×W, I= J×S, 2mm≤L1≤6.5mm, ΔL≥4mm.

2. The battery cell according to claim 1, wherein, Along the X direction, the side distance of the laser welding mark to the ultrasonic welding mark is L2, and the unit is mm, Along the Y direction, the side distance of the laser welding mark to the pole post bottom plate is L3, and the unit is mm, Along the Y direction, the side distance of the laser welding mark to the ultrasonic welding mark is L4, and the unit is mm, Satisfies: 1.5mm≤L2≤5mm, 2mm≤L3≤4.5mm, 1.5mm≤L4≤4mm. Along the X direction, the ultrasonic welding mark is a continuous one; or, along the X direction, the ultrasonic welding mark is a plurality of ones, and adjacent ultrasonic welding marks have an overlapping area.

3. The cell of claim 1 or 2, wherein, Along the X direction, the laser welding mark is a continuous one; or, along the X direction, the laser welding mark is a plurality of ones, and adjacent laser welding marks have an overlapping area.

4. The cell of claim 1 or 2, wherein, The cross-sectional shape of the pole post column along the X-Y plane is circular; 5. The cell of claim 1 or 2, wherein, Or, the cross-sectional shape of the pole post column along the X-Y plane is a racetrack shape, comprising two oppositely arranged straight edge segments and a circular arc segment connecting the two straight edge segments, and the straight edge segments are arranged along the X direction. The material of the pole post is pure copper or pure aluminum.

6. The cell of claim 1 or 2, wherein, The pole post bottom plate comprises a bottom plate main body and a bottom plate column segment protruding from the bottom plate main body, the pole post column and the bottom plate column segment are integrally connected, the pole post bottom plate is made of copper material, and the pole post column is made of aluminum material.

7. The cell of claim 1 or 2, wherein, The cover plate assembly further comprises:

8. The cell of claim 1 or 2, wherein, A riveting block is provided with a number of second pole post mounting holes corresponding to the pole post columns; the riveting block is arranged on the second surface of the cover plate body; A first insulating piece is provided with a number of third pole post mounting holes corresponding to the pole post columns; the first insulating piece is arranged between the riveting block and the second surface of the cover plate body, and insulatingly connects the riveting block and the cover plate body. ​ A second insulating piece is provided with a corresponding number of fourth pole post mounting holes corresponding to the pole post bodies; the second insulating piece is arranged between the first surface of the cover plate body and the pole post bottom plate, and insulatingly connects the cover plate body and the pole post bottom plate; The pole post bodies pass through the fourth pole post mounting holes, the first pole post mounting holes, the third pole post mounting holes and the second pole post mounting holes in sequence, and are riveted or welded with the riveting blocks.

9. The cell of claim 1 or 2, wherein, Further comprising a shell having a receiving cavity, the shell being provided with at least one open end communicating with the receiving cavity; The pole group is arranged in the receiving cavity, and the pole group has positive and negative tabs drawn out; The cover plate assembly is arranged at the open end of the shell, and the pole group is encapsulated in the shell; the pole posts include positive and negative pole posts, the positive pole posts are welded with the positive tabs, and the negative pole posts are welded with the negative tabs.

10. A battery pack, characterized by, A plurality of the battery cell according to any one of claims 1-9 are electrically connected between each other.

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