Core cladding structure and square battery cell

Abstract

The utility model provides a core package structure and a square electric core, relates to the battery technical field, the core package structure comprises 2n laminated roll cores, n is greater than or equal to 2, the roll cores are grouped according to a one-to-one correspondence mode to form n roll core groups, each roll core group comprises two roll cores, the two roll cores at the central position of the laminated arrangement form a central roll core group, and n is greater than or equal to 2. The roll cores located on the two sides of the center roll core set are sequentially and symmetrically grouped outwards to form a plurality of outer side roll core sets. Tabs are arranged on the two sides of the roll core in the length direction respectively, the tabs in the central roll core group are located below the core cladding structure and gradually get away from the roll core groups from the center to the outside, and the positions of the tabs on each outer roll core group in the height direction of the core cladding structure are sequentially increased relative to the tabs close to the central roll core group. According to the core cladding structure disclosed by the utility model, the tabs on all the roll cores can be conveniently welded with the surfaces of different heights of the connecting sheets, so that the welding operability and the welding efficiency of the tabs and the connecting sheets are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power batteries, in particular to a core package structure and a square battery core. Background Art

[0002] As the energy storage industry develops rapidly, energy storage projects are accelerating towards the GWh era, placing stringent requirements on energy storage systems and batteries, which account for about 60% of their costs, such as greater capacity, higher safety, and longer life. Battery companies have launched large-capacity energy storage batteries with a capacity of 310Ah+ to cope with the fierce market competition.

[0003] In the related art, more winding cores are usually arranged in the shell to increase the capacity of the square battery cell, thereby improving the power supply endurance to the power terminal. However, as the number of winding cores increases, the number of tabs will also increase. If the traditional battery cell structure is still used, that is, the tabs at the top of the winding core and the poles on the top cover are connected through connecting sheets, it will inevitably lead to an increase in the length and folding thickness of the tabs, wasting the internal space of the battery cell, thereby reducing the capacity of the square battery cell.

[0004] For example, the patent with the publication number CN219393638U discloses a large-capacity square battery, which is formed by arranging multiple winding cores side by side in the shell, with pole ears on both sides of the winding core, and connecting pieces are respectively arranged on both sides of the winding core, one end of the connecting piece is welded to the pole ear, and the other end is welded to the pole column. In the welding process of the pole ear and the connecting piece, the pole ear needs to be folded to the outer surface of the connecting piece to implement welding. When the winding core is a double winding core, the pole ears on the double winding core can be folded relatively on both sides along the width direction of the connecting piece. When the number of winding cores is greater than two, the pole ears on the middle winding core cannot be folded onto the connecting piece. At this time, it is necessary to cut a slit on the connecting piece for the pole ears to pass through the connecting piece. When the slit of the connecting piece is too small, it is not convenient for the pole ears to pass through. When the slit of the connecting piece is too large, the welding area between the pole ears and the connecting piece is reduced, affecting the current capacity. Therefore, although the square cell structure disclosed in the above-mentioned prior art can improve the cell capacity, it has problems such as inconvenient tab welding operation, small welding area between the tab and the connecting sheet, and low current carrying capacity during the welding process of multiple winding cores and connecting sheets. Utility Model Content

[0005] In view of this, the utility model proposes a core package structure and a square battery cell to solve the problem of inconvenient tab welding operation during the welding process of a plurality of side tab structure core rolls and connecting sheets.

[0006] The technical solution of the utility model is achieved in this way:

[0007] On the one hand, the utility model provides a core package structure, the core package structure includes 2n stacked cores, where n≥2, the cores are grouped in a one-to-one correspondence to form n core groups, each core group includes two cores, wherein the two cores located at the center of the stacked arrangement constitute a central core group, and the cores located on both sides of the central core group are symmetrically grouped outward in turn to form a plurality of outer core groups;

[0008] The core is provided with pole ears on both sides along the length direction, and the pole ears on the central core group are located below the core package structure. As the core groups gradually move away from the center to the outside, the positions of the pole ears on each group of outer core groups in the height direction of the core package structure are successively increased relative to the pole ears close to the central core group.

[0009] On the basis of the above technical solution, preferably, the pole ears on the central core group are arranged at a first height position of the core package structure, and the pole ears on the outer core group are arranged at a second height position of the core package structure, and the second height position and the first height position are staggered with each other in the height direction of the core package structure.

[0010] Further, preferably, the tabs of two adjacent outer winding core groups have a first spacing in the height direction, and the tabs of the central winding core group have a second spacing with the tabs of the outer winding core group immediately above it, wherein the first spacing and the second spacing are the same.

[0011] In the second aspect, the utility model discloses a square battery cell, comprising a shell, a top cover, a connecting plate and the core package structure described in the first aspect, wherein the core package structure is arranged in the shell, the top cover is arranged at the open end of the shell, one end of the connecting plate is connected in parallel with the pole ear on the core package structure, and the other end is connected to the pole arranged on the top cover.

[0012] On the basis of the above technical solution, preferably, the connecting piece includes a horizontal section and a vertical section vertically connected to one end of the horizontal section, the horizontal section is used to connect to the pole on the top cover, and the vertical section includes a central welding portion and at least one outer welding portion, and the at least one outer welding portion is connected sequentially from bottom to top, the central welding portion is connected to the lowest outer welding portion, the uppermost outer welding portion is connected to the horizontal section, the central welding portion is connected to the pole ear on the central core group, and the outer welding portions are respectively connected to the pole ears on the corresponding outer core group in the height direction of the core package structure.

[0013] Further, preferably, the width of the outer welding portion is matched to the distance between two pole tabs on the corresponding outer winding core group, and the height of the outer welding portion is greater than or equal to the width of the pole tab on the corresponding outer winding core group.

[0014] Further, preferably, a notch is provided at the center of the length direction of the central welding portion, and the width of the notch is greater than or equal to the distance between two tabs on the central winding core assembly.

[0015] Preferably, the distance from the edge of the notch to the edge of the central welding portion in the width direction is greater than or equal to the length of the pole lug on the central winding core assembly.

[0016] On the basis of the above technical solution, preferably, an explosion-proof valve is provided at the bottom of the shell, a plurality of support parts are provided on the inner bottom surface of the shell, and an exhaust passage is formed between the support parts and the bottom surface of the core package structure.

[0017] Further, preferably, a support sheet is provided between the bottom surface of the core package structure and the support portion, and a weak area is provided at a position of the support sheet corresponding to the explosion-proof valve, and the weak area can be broken when thermal runaway occurs in the winding core.

[0018] Compared with the prior art, the utility model has the following beneficial effects:

[0019] (1) In the height direction of the core package structure, the positions of the pole ears on the outer winding core group are successively increased relative to the pole ears on the central winding core group, thereby making it possible for the pole ears on both sides of the width direction of the connecting sheet to be staggered along the height direction of the core package structure, so that the pole ears on all the winding cores can be intuitively and conveniently welded to the surfaces of different heights of the connecting sheet, thereby improving the operability and welding efficiency of the pole ears and the connecting sheet.

[0020] (2) By staggering the pole tabs on different winding core groups in the height direction of the core package structure, when the connecting piece is vertically arranged at the center of the side wall of the core package structure, the connecting piece can be welded to the pole tabs at different heights through a simplified process, thereby reducing the complexity of the welding process and improving the welding efficiency.

[0021] (3) By setting the spacing of the tabs on different winding core groups to be consistent in the height direction of the core package structure, the welding spacing of all tabs in the height direction of the connecting piece can be guaranteed to be consistent. In this way, the welding operation can use the same setting parameters and tools, which is convenient for automated equipment to perform welding and improve welding production efficiency. Welding at a predetermined position can improve the consistency and reliability of the connection between the tab and the connecting piece. At the same time, the consistency of the welding point of the tab on the connecting piece can better dissipate heat.

[0022] (4) A notch is provided at the center of the length direction of the central welding part, and the width of the notch is greater than or equal to the distance between the two tabs on the central winding core group. In this way, during the installation of the connecting sheet and the core package structure, the two tabs on the central winding core group are placed in the notch, so that the two tabs in the notch are folded outward respectively, so that the tabs are folded to the surface of the central welding part on one side of the notch, so that the welding area between the tabs on the central winding core group and the connecting sheet can be increased, thereby improving the current carrying capacity.

[0023] (5) By setting the explosion-proof valve at the bottom of the shell, the spread of thermal runaway can be reduced, greatly improving the safety of the square battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a three-dimensional structural schematic diagram of the core package structure disclosed in the utility model;

[0026] Figure 2 This is a schematic diagram of the first structure of the connecting piece disclosed in the utility model;

[0027] Figure 3 It is a schematic diagram of the assembly structure of the first core package structure and the first connecting piece of the utility model;

[0028] Figure 4 This is a schematic diagram of the second structure of the connecting piece disclosed in the utility model;

[0029] Figure 5 It is a schematic diagram of the second core package structure and the second connecting piece assembly structure of the utility model;

[0030] Figure 6 This is an exploded schematic diagram of the square battery disclosed in the utility model;

[0031] Figure 7 This is a schematic diagram of the planar structure of a square battery disclosed in the utility model;

[0032] Figure 8 for Figure 7 A partial enlarged view of the middle part;

[0033] Fig. 9 for Figure 7 A partial enlarged view of the B site;

[0034] Reference numerals:

[0035] 1. Core package structure; 10. Core; 11. Center core group; 12. Outer core group; 101. Pole ear; 2. Shell; 3. Top cover; 4. Connecting plate; 31. Pole; 41. Horizontal section; 42. Vertical section; 421. Center welding part; 422. Outer welding part; 4211. Notch; 21. Explosion-proof valve; 22. Support part; 20. Exhaust channel; 5. Support plate; 51. Weak area; 6. Insulating film. DETAILED DESCRIPTION

[0036] The following will be combined with the implementation of the utility model to clearly and completely describe the technical solutions in the implementation of the utility model. Obviously, the described implementation is only a part of the implementation of the utility model, not all of the implementations. Based on the implementation of the utility model, all other implementations obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0037] like Figure 1 As shown, combined Figure 3 and 5 The embodiment of the utility model discloses a core package structure, the core package structure 1 includes 2n stacked winding cores 10, wherein n≥2, thus, the entire core package structure 1 is composed of at least 4 winding cores 10, and the stacked arrangement of multiple winding cores 10 can increase the capacity of the battery cell, and the core package structure 1 can be set to 6, 8 or more according to the battery cell capacity requirements.

[0038] In this embodiment, the cores 10 are grouped in a one-to-one correspondence to form n core groups, each core group contains two cores 10, and the cores 10 are respectively provided with pole ears 101 on both sides along the length direction. The purpose of such a setting is to facilitate the vertical arrangement of the connecting sheet 4 on the side wall of the entire core package structure 1, so that the two cores 10 on each core group can be welded to the two sides of the connecting sheet 4 in the width direction respectively.

[0039] In order to facilitate the welding of the pole ears 101 of all the cores 10 on the core package structure 1 to the connecting piece 4, the present embodiment is arranged as follows when dividing the core groups: the two cores 10 located at the center of the stacked arrangement constitute a central core group 11, and the cores 10 located on both sides of the central core group 11 are symmetrically grouped outward in turn to form a number of outer core groups 12. For example, when the number of cores 10 in the present embodiment is 4, the number of outer core groups 12 is one, and when the number of cores 10 is 6, the number of outer core groups 12 is 2.

[0040] In the prior art, usually the pole ears 101 on the side walls of multiple cores 10 are at the same height, which is not convenient for welding the connecting sheet 4 to the multiple pole ears 101 at the same height. In this embodiment, under the above-mentioned core 10 grouping mechanism, the positions of the pole ears 101 on the grouped core groups are further defined. Specifically, the pole ears 101 on the cores 10 in the central core group 11 are located below the core package structure 1. As the core groups gradually move away from the center to the outside, the positions of the pole ears 101 on each group of outer core groups 12 in the height direction of the core package structure 1 are successively increased relative to the pole ears 101 close to the central core group 11.

[0041] According to the arrangement, when the connecting sheet 4 is vertically located at the center of the side wall of the core package structure 1, the winding cores 10 on both sides of the width direction of the connecting sheet 4 are grouped into a winding core group one by one, and in the height direction of the core package structure 1, the positions of the pole ears 101 on the outer winding core group 12 are successively increased relative to the pole ears 101 on the central winding core group 11, thereby making it possible for the pole ears 101 on both sides of the width direction of the connecting sheet 4 to be staggered along the height direction of the core package structure 1, so that the pole ears 101 on all the winding cores 10 can be intuitively and conveniently welded to the surfaces of different heights of the connecting sheet 4, thereby improving the welding operability and welding efficiency of the pole ears 101 and the connecting sheet 4.

[0042] As some preferred embodiments, the pole lugs 101 on the central core group 11 are arranged at a first height position of the core package structure 1, and the pole lugs 101 on the outer core group 12 are arranged at a second height position of the core package structure 1, and the second height position and the first height position are staggered with each other in the height direction of the core package structure 1.

[0043] With such a structural arrangement, when the connecting piece 4 is vertically arranged at the center of the side wall of the core package structure 1, the connecting piece 4 can be welded to the pole ears 101 of different heights through a simplified process, thereby reducing the complexity of the welding process and improving the welding efficiency.

[0044] Specifically, in terms of optimizing the welding sequence, since the pole lugs 101 of the central core group 11 and the outer core group 12 are differentiated in height, the welding sequence can be planned more easily. In actual operation, the pole lug 101 at one height position can be welded first, and then the pole lug 101 at another height position can be welded, instead of welding multiple pole lugs 101 at the same height plane at the same time. At the same time, if all the pole lugs 101 are located in the same plane, the welding robot arm or operator may be subject to space constraints when approaching and operating, especially when welding the inner pole lug 101. The staggered design allows easier access to each pole lug 101, so the welding work can be completed more safely and accurately.

[0045] In terms of reducing welding interference, when multiple tabs 101 are located at the same height, the heat-affected zones during welding may overlap each other, resulting in affected welding quality between adjacent tabs 101. By staggering the tabs 101, such thermal interference can be reduced, thereby improving welding quality.

[0046] As some preferred embodiments, the tabs 101 of two adjacent outer core groups 12 have a first spacing in the height direction, and the tabs 101 of the central core group 11 have a second spacing with the tabs 101 of the outer core group 12 immediately above it, wherein the first spacing and the second spacing are the same.

[0047] By adopting the above technical solution, the spacing is consistent, which can ensure that the welding spacing of all the tabs 101 in the height direction of the connecting piece 4 is consistent. In this way, the welding operation can use the same setting parameters and tools, which is convenient for automated equipment to perform welding and improve welding production efficiency. Welding at a predetermined position can improve the consistency and reliability of the connection between the tab 101 and the connecting piece 4. At the same time, the consistency of the welding point of the tab 101 on the connecting piece 4 can better dissipate heat.

[0048] Refer to the attached Figure 6 As shown, the present embodiment also discloses a square battery cell, including a shell 2, a top cover 3, a connecting piece 4 and the core package structure 1 disclosed above, the core package structure 1 is arranged in the shell 2, the top cover 3 is arranged at the open end of the shell 2, one end of the connecting piece 4 is connected in parallel with the pole ear 101 on the core package structure 1, and the other end is connected to the pole 31 arranged on the top cover 3.

[0049] By adopting the above technical scheme, a plurality of winding cores 10 are stacked and arranged inside the shell 2 along the thickness direction of the shell 2 to form a core package structure 1. Two connecting plates 4 are provided, which are respectively located on both sides of the length direction of the winding core 10. The connecting plate 4 is vertically arranged at the center of the side wall of the core package structure 1. The upper end of the connecting plate 4 is welded to the pole 31 on the top cover 3, and the lower end of the connecting plate 4 is welded in parallel to the plurality of pole ears 101 on the core package.

[0050] In the above embodiment, after the core package structure 1 is welded to the connecting sheet 4 and the top cover 3 , an insulating film 6 is wrapped around the outer side of the core package structure 1 to prevent the winding core 10 and the shell 2 from contacting and short-circuiting.

[0051] Since the winding cores 10 on both sides of the connecting sheet 4 in the width direction are grouped into a winding core group one by one, in the height direction of the core package structure 1, the positions of the pole ears 101 on the outer winding core group 12 are successively increased relative to the pole ears 101 on the central winding core group 11, thereby making it possible for the pole ears 101 on both sides of the connecting sheet 4 in the width direction to be staggered along the height direction of the core package structure 1, so that the pole ears 101 on all the winding cores 10 can be intuitively and conveniently welded to the surfaces of different heights of the connecting sheet 4, thereby improving the welding operability and welding efficiency of the pole ears 101 and the connecting sheet 4.

[0052] As some preferred implementations, refer to the attached Figure 2-5As shown, the connecting piece 4 includes a horizontal section 41 and a vertical section 42 vertically connected to one end of the horizontal section 41, the horizontal section 41 is used to connect to the pole 31 on the top cover 3, and the vertical section 42 includes a central welding portion 421 and at least one outer welding portion 422, and at least one outer welding portion 422 is connected sequentially from bottom to top, the central welding portion 421 is connected to the lowest outer welding portion 422, and the uppermost outer welding portion 422 is connected to the horizontal section 41, the central welding portion 421 is connected to the pole ear 101 on the central core group 11, and the outer welding portions 422 are respectively connected to the pole ears 101 on the corresponding outer core groups 12 in the height direction of the core package structure 1.

[0053] By adopting the above technical solution, during the connection process between the top cover 3 and the core package structure 1, the horizontal section 41 on the connecting sheet 4 is first welded to the pole 31 on the top cover 3, and then the core package structure 1 is placed on the top cover 3, and then the vertical section 42 is sequentially welded to the multiple pole tabs 101 on the side wall of the core package structure 1. By setting the central welding part 421 and the outer welding part 422, the pole tabs 101 of different heights of the core package structure 1 can be respectively welded to the corresponding welding parts, and the pole tabs 101 do not interfere with each other during the welding process. Multiple pole tabs 101 are welded to the connecting sheet 4 in batches and layers, which can reduce the difficulty of welding and improve the welding efficiency.

[0054] As some preferred embodiments, the width of the outer welding portion 422 is adapted to the spacing between the two pole tabs 101 on the corresponding outer winding core group 12. Thus, when the vertical section 42 is vertically placed at the center of the side wall of the core package structure 1, the spacing between the two pole tabs 101 on the outer winding core group 12 can accommodate the outer welding portion 422. In this way, it is convenient for the pole tabs 101 on both sides of the outer welding portion 422 to be folded to the surface of the outer welding portion 422, so that the two pole tabs 101 on the outer winding core group 12 can be symmetrically welded on the surface of the outer welding portion 422, and the welding process is simple and orderly. The height of the outer welding portion 422 is greater than or equal to the width of the pole tab 101 on the corresponding outer winding core group 12. Thus, when the pole tab 101 on the outer winding core group 12 is welded on the surface of the outer welding portion 422, there is a certain fault tolerance space, that is, it is convenient for the entire connecting sheet 4 to be installed at the position of the side wall of the core package structure 1, and it can ensure the maximum welding area between the pole tab 101 and the outer welding portion 422, and ensure the current capacity.

[0055] Since the two winding cores 10 on the central winding core group 11 are close to each other, the distance between the pole ears 101 on the two winding cores 10 is small. If the central welding part 421 is placed between the pole ears 101 of the two winding cores 10, this will cause the welding area between the pole ears 101 and the central welding part 421 to be too small, and the current capacity cannot be met.

[0056] To this end, the solution adopted in this embodiment is to open a notch 4211 at the center of the length direction of the central welding part 421, and the width of the notch 4211 is greater than or equal to the distance between the two pole tabs 101 on the central winding core group 11. In this way, during the installation of the connecting sheet 4 and the core package structure 1, the two pole tabs 101 on the central winding core group 11 are placed in the notch 4211, so that the two pole tabs 101 in the notch 4211 are folded outward respectively, so that the pole tabs 101 are folded to the surface of the central welding part 421 on one side of the notch 4211, so that the welding area between the pole tabs 101 on the central winding core group 11 and the connecting sheet 4 can be increased, thereby improving the current capacity.

[0057] Furthermore, the distance from the edge of the notch 4211 to the edge of the central welding portion 421 in the width direction is greater than or equal to the length of the tab 101 on the central winding core group 11. This arrangement ensures that the tab 101 on the central winding core group 11 can be completely covered on the surface of the central welding portion 421, thereby increasing the welding area between the tab 101 and the connecting sheet 4, thereby increasing the current capacity.

[0058] As some preferred implementations, refer to the attached Figure 7-9 As shown, in this embodiment, an explosion-proof valve 21 is arranged at the bottom of the shell 2, and a plurality of support parts 22 are arranged on the inner bottom surface of the shell 2, and an exhaust channel 20 is formed between the support parts 22 and the bottom surface of the core package structure 1. With the above technical solution, the explosion-proof valve 21 is arranged at the bottom of the shell 2, and when the winding core 10 inside the shell 2 has thermal runaway, the high-pressure gas breaks through the explosion-proof valve 21 through the exhaust channel 20 and is discharged from the bottom of the shell 2. Compared with the solution in which the explosion-proof valve 21 is arranged at the top cover 3, the explosion-proof valve 21 is arranged at the bottom of the shell 2, which can reduce the spread of thermal runaway to other cells after the square battery cell has thermal runaway. Since electrical connection components, such as bus bars and wiring harnesses, are mostly arranged above the top cover 3, the explosion-proof valve 21 is conventionally arranged on the top cover 3. When the battery cell has thermal runaway, the thermal runaway is likely to cause an impact on the wiring harness, causing a short circuit and causing thermal runaway in other batteries. The explosion-proof valve 21 is placed on the bottom surface of the shell 2. In this way, the high-pressure gas generated by the thermal runaway is discharged from the bottom surface of the shell 2 without affecting the wiring harness. At the same time, a liquid cooling plate is usually arranged at the bottom of the battery cell, which will to a certain extent cool the high-temperature and high-pressure gas after the thermal runaway occurs. Therefore, the explosion-proof valve 21 is arranged at the bottom of the shell 2, which can greatly improve the safety of the square battery cell.

[0059] In this embodiment, some recessed parts may be provided on the bottom surface of the housing 2 to improve the structural strength of the housing 2. Preferably, the recessed parts and the supporting part 22 may be at the same position on the bottom surface of the housing 2. The recessed parts may be similar to a cross-shaped or L-shaped embossing structure.

[0060] As some other embodiments, a support sheet 5 is further provided between the bottom surface of the core package structure 1 and the support portion 22. By providing the support sheet 5, it is possible to avoid stress concentration caused by direct contact between the bottom of the core 10 and the support portion 22. A weak area 51 is provided at a position corresponding to the support sheet 5 and the explosion-proof valve 21. The weak area 51 can be broken when thermal runaway occurs in the core 10. When thermal runaway occurs in the core 10, the weak area 51 can be broken, and then the explosion-proof valve 21 can be broken through through the exhaust channel 20 and discharged. The weak area 51 can be an annular notch or a cross notch.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A core package structure (1), characterized in that: The core package structure (1) comprises 2n winding cores (10) arranged in a stacked manner, wherein n≥2, and the winding cores (10) are grouped in a one-to-one correspondence to form n winding core groups, each winding core group comprising two winding cores (10), wherein the two winding cores (10) located at the center of the stacked arrangement constitute a central winding core group (11), and the winding cores (10) located on both sides of the central winding core group (11) are sequentially grouped symmetrically outward to form a plurality of outer winding core groups (12); The winding core (10) is provided with pole ears (101) on both sides along the length direction, and the pole ears (101) on the winding core (10) in the central winding core group (11) are located below the core package structure (1), and as the winding core group gradually moves away from the center to the outside, the position of the pole ears (101) on each group of outer winding core groups (12) in the height direction of the core package structure (1) is successively increased relative to the pole ears (101) on the central winding core group (11).

2. The core package structure (1) according to claim 1, characterized in that: The pole lugs (101) on the central winding core group (11) are arranged at a first height position of the core package structure (1), and the pole lugs (101) on the outer winding core group (12) are arranged at a second height position of the core package structure (1), and the second height position and the first height position are staggered with each other in the height direction of the core package structure (1).

3. The core package structure (1) according to claim 2, characterized in that: The pole lugs (101) of two adjacent outer winding core groups (12) have a first spacing in the height direction, and the pole lugs (101) of the central winding core group (11) and the pole lugs (101) of the outer winding core group (12) immediately above it have a second spacing, wherein the first spacing and the second spacing are the same.

4. A square battery cell, comprising a shell (2), a top cover (3), a connecting sheet (4) and the core package structure (1) as claimed in claim 3, characterized in that: The core package structure (1) is arranged in the shell (2), the top cover (3) is arranged at the open end of the shell (2), one end of the connecting piece (4) is connected in parallel with the pole ear (101) on the core package structure (1), and the other end is connected to the pole (31) arranged on the top cover (3).

5. The square battery cell according to claim 4, characterized in that: The connecting piece (4) comprises a horizontal section (41) and a vertical section (42) vertically connected to one end of the horizontal section (41); the horizontal section (41) is used to connect to the pole (31) on the top cover (3); the vertical section (42) comprises a central welding portion (421) and at least one outer welding portion (422); the at least one outer welding portion (422) is connected in sequence from bottom to top; the central welding portion (421) is connected to the lowest outer welding portion (422); the highest outer welding portion (422) is connected to the horizontal section (41); the central welding portion (421) is connected to the pole lug (101) on the central winding core group (11); and the outer welding portions (422) are respectively connected to the pole lugs (101) on the corresponding outer winding core groups (12) in the height direction of the core package structure (1).

6. The square battery cell according to claim 5, characterized in that: The width of the outer welding portion (422) is matched to the distance between the two pole lugs (101) on the corresponding outer winding core group (12), and the height of the outer welding portion (422) is greater than or equal to the width of the pole lug (101) on the corresponding outer winding core group (12).

7. The square battery cell according to claim 5, characterized in that: A notch (4211) is provided at the center of the central welding portion (421) in the length direction, and the width of the notch (4211) is greater than or equal to the distance between the two pole ears (101) on the central winding core group (11).

8. The square battery cell according to claim 7, characterized in that: The distance from the edge of the notch (4211) to the edge of the central welding portion (421) in the width direction is greater than or equal to the length of the pole lug (101) on the central winding core assembly (11).

9. The square battery cell according to claim 4, characterized in that: An explosion-proof valve (21) is provided at the bottom of the shell (2), a plurality of support portions (22) are provided on the inner bottom surface of the shell (2), and an exhaust passage (20) is formed between the support portions (22) and the bottom surface of the core package structure (1).

10. The square battery cell according to claim 9, characterized in that: A support sheet (5) is also provided between the bottom surface of the core package structure (1) and the support portion (22), and a weak area (51) is provided at a position of the support sheet (5) corresponding to the explosion-proof valve (21), and the weak area (51) can be broken when thermal runaway occurs in the winding core (10).

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