Battery assembly and battery module

Abstract

The invention discloses a battery assembly and a battery module, and belongs to the technical field of battery production. The battery assembly comprises a roll core, a convergence disc and a cover plate. In the winding direction of the pole piece, the maximum width of each through hole in the convergence disc is smaller than the width of the pole lug. Therefore, the tabs can be tightly pressed through the confluence plate, and a certain tab in the plurality of tabs is effectively prevented from warping out of the through hole of the confluence plate, so that the reliability of the battery can be improved. Besides, at least two through holes are formed, so that even if the maximum width of each through hole is smaller than the width of the second tab, the overall pressure relief area of the battery is not influenced, and excessive gas generated by a battery fault can still be smoothly discharged through the at least two through holes and the explosion-proof valve at the mounting opening; therefore, the normal pressure relief function of the explosion-proof valve is not influenced, and the safety and reliability of the battery are further enhanced.

Description

Technical Field

[0001] The present application relates to the field of battery production technology, and in particular to a battery assembly and a battery module. Background Art

[0002] The battery is usually composed of a metal shell, a winding core, a busbar, and a cover plate. The winding core may include a stacked positive electrode sheet and a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet. Here, the positive electrode sheet, the separator, and the negative electrode sheet may be wound together to obtain a winding core.

[0003] A plurality of evenly arranged positive electrode tabs are arranged on one side of the positive electrode sheet in the winding core, and a plurality of evenly arranged negative electrode tabs are arranged on one side of the negative electrode sheet. The plurality of positive electrode tabs can be bent and welded to a busbar, and the plurality of negative electrode tabs can also be bent and welded to another busbar, and the two busbars can be distributed at both ends of the battery.

[0004] However, there are openings on the busbars at both ends of the battery. It is very easy for one of the multiple positive pole ears to be lifted out of the opening of the corresponding busbar, and it is also very easy for one of the multiple negative pole ears to be lifted out of the opening of the corresponding busbar, resulting in low reliability of the battery. Summary of the invention

[0005] The embodiment of the present application provides a battery assembly and a battery module. It can solve the problem of poor reliability of batteries in the prior art. The technical solution is as follows:

[0006] In one aspect, a battery assembly is provided, comprising:

[0007] cores, manifolds and covers;

[0008] The winding core comprises: a pole piece wound as a whole, and a plurality of pole ears connected to one side of the pole piece, wherein the plurality of pole ears can be bent in a direction toward the central axis of the winding core;

[0009] The busbar is located at one end of the winding core, and the busbar is welded to at least a portion of the bent pole lug; the busbar has at least two through holes, and in the winding direction of the pole piece, the maximum width of each through hole is smaller than the width of the pole lug;

[0010] The cover plate is connected to a side of the busbar facing away from the winding core, and the cover plate has a mounting opening, and the mounting opening is connected to the at least two through holes.

[0011] Optionally, each of the through holes comprises: a connected rectangular area and a fan-shaped area, wherein the rectangular area is closer to the outer boundary of the busbar than the fan-shaped area;

[0012] Wherein, in the winding direction of the pole piece, the maximum width of the through hole is the width of the rectangular area.

[0013] Optionally, when the number of the through holes in the busbar is two, the busbar further comprises: a support bar located between the two through holes;

[0014] Wherein, the two through holes are symmetrically distributed on both sides of the center line of the support bar.

[0015] Optionally, the diameter of the circle where the sector-shaped area is located is equal to the sum of the widths of the two rectangular areas in the two through holes and the width of the support bar.

[0016] Optionally, in the same through hole, a distance between a side of the rectangular area away from the fan-shaped area and an outer boundary of the busbar is greater than 0.

[0017] Optionally, the orthographic projections of the at least two through holes on the end surface of the winding core are located within the orthographic projection of the mounting opening in the cover plate on the end surface of the winding core.

[0018] Optionally, the busbar includes: a busbar body and a connecting portion connected to each other; the at least two through holes are located on the busbar body, and the cover plate is connected to the connecting portion.

[0019] Optionally, the number of the pole pieces is two, namely a first pole piece and a second pole piece; the pole lug connected to the first pole piece is a first pole lug, and the pole lug connected to the second pole piece is a second pole lug, and a plurality of the first pole lugs and a plurality of the second pole lugs are respectively distributed at both ends of the winding core;

[0020] There are two busbars, namely a first busbar and a second busbar. The first busbar is welded to at least a portion of the first electrode tab after bending, and the second busbar is welded to at least a portion of the second electrode tab after bending.

[0021] Optionally, the cover plate includes: a first cover plate and a second cover plate, the first cover plate is located on the side of the first bus plate away from the winding core, and the installation opening on the first cover plate is used to inject electrolyte; the second cover plate is located on the side of the second bus plate away from the winding core, and the installation opening on the second cover plate is used to install an explosion-proof valve.

[0022] In another aspect, a battery module is provided, comprising:

[0023] A plurality of connected battery assemblies, wherein the battery assembly is any one of the battery assemblies described above.

[0024] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0025] Since the maximum width of each through hole in the busbar is smaller than the width of the pole ear in the winding direction of the pole piece, the busbar can be tightly pressed together with the pole ear, effectively preventing one of the multiple pole ears from tilting out of the through hole of the busbar, thereby improving the reliability of the battery. For example, when the busbar is in the first busbar position, the first busbar can tightly press the first pole ear, effectively preventing one of the multiple first pole ears from tilting out of the through hole of the first busbar, avoiding the first pole ear from obstructing the electrolyte flow path, ensuring uniform infiltration of the electrolyte, and improving the reliability of the battery. When the busbar is in the second busbar position, the second busbar can tightly press the second pole ear, preventing one of the multiple second pole ears from tilting out of the through hole of the second busbar. This avoids the abnormal opening caused by the second pole ear accidentally touching the explosion-proof valve, and enhances the reliability of the battery. In addition, since at least two through holes are provided, even if the maximum width of each through hole is smaller than the width of the second pole ear, it will not affect the overall pressure relief area of ​​the battery, so that the excess gas generated by the battery failure can still be smoothly discharged through the at least two through holes and the explosion-proof valve at the installation opening to ensure that the normal pressure relief function of the explosion-proof valve is not affected, thereby further enhancing the safety and reliability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 is an exploded view of a battery assembly provided in an embodiment of the present application;

[0028] Figure 2 It is a structural schematic diagram of a winding core provided by the implementation of this application;

[0029] Figure 3 yes Figure 2 A top view of the end face of the winding core is shown;

[0030] Figure 4 This is a schematic diagram of the structure of a busbar and a cover plate before installation provided in an embodiment of the present application;

[0031] Figure 5 It is a schematic diagram of the structure of another winding core provided by the present application;

[0032] Figure 6 This is a schematic diagram of the structure of another busbar and cover plate before installation provided in an embodiment of the present application;

[0033] Figure 7 This is a schematic diagram of the structure of another busbar and cover plate before installation provided in an embodiment of the present application;

[0034] Figure 8 It is a welding power waveform diagram provided in an embodiment of the present application;

[0035] Fig. 9 This is another welding power waveform diagram provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0037] In the related art, the battery is usually composed of a metal shell, a winding core, a busbar, and a cover plate. The winding core may include a stacked positive electrode sheet and a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet. A plurality of evenly arranged positive electrode tabs are provided on one side of the positive electrode sheet in the winding core, and a plurality of evenly arranged negative electrode tabs are provided on one side of the negative electrode sheet. Multiple positive electrode tabs can be bent and welded to a busbar, and multiple negative electrode tabs can also be bent and welded to another busbar.

[0038] However, there are openings on the busbars at both ends of the battery, and one of the multiple positive pole tabs is very likely to be lifted out of the opening of the corresponding busbar. Since the opening on the busbar at the positive pole tab is usually used to inject electrolyte, after the positive pole tab is very likely to be lifted out of the opening of the corresponding busbar, the lifted positive pole tab will block the flow path of the electrolyte, thereby affecting the infiltration effect of the electrolyte, and further resulting in low battery reliability.

[0039] Similarly, one of the multiple negative electrode tabs is also very easy to be lifted out of the opening of the corresponding busbar. Since the opening on the busbar at the negative electrode tab is usually used to communicate with the explosion-proof valve on the cover plate, after the negative electrode tab is easily lifted out of the opening of the corresponding busbar, the lifted negative electrode tab may accidentally touch the explosion-proof valve, causing the explosion-proof valve to open abnormally, thereby affecting the safety of the battery and resulting in low battery reliability.

[0040] Please refer to Figure 1 , Figure 1 000 is an exploded view of a battery assembly provided in an embodiment of the present application. The battery assembly 000 may include: a winding core 100 , a busbar 200 and a cover plate 300 .

[0041] The battery assembly 000 may further include a housing 400 , which may be used to accommodate the winding core 100 .

[0042] To more clearly see the structure of the core 100, please refer to Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the structure of a winding core provided by the present application. Figure 3 yes Figure 2 The winding core 100 in the battery assembly 000 may include: a pole piece 102 wound as one body, and a plurality of pole tabs 101 connected to one side of the pole piece, and the plurality of pole tabs 101 can be bent in a direction toward the central axis L of the winding core 100 .

[0043] To more clearly see the structure of the busbar 200 and the cover plate 300, please refer to Figure 4 , Figure 4 2 is a schematic diagram of a busbar and a cover plate before installation provided in an embodiment of the present application. The busbar 200 in the battery assembly 000 may be located at one end of the winding core 100, and the busbar 200 may be welded to at least a portion of the bent tab 101.

[0044] It should be noted that the busbar 200 and the cover plate 300 are connected together and in an unfolded state before installation. The busbar 200 in the battery assembly 000 may include: a busbar body 201 and a connecting portion 202 connected to each other; the cover plate 300 may be connected to the connecting portion 202. After the busbar body 201 is welded to at least part of the bent tab 101, the connecting portion 202 may be bent so that the cover plate 300 may be located on the side of the busbar body 201 away from the winding core 100.

[0045] The busbar 200 may have at least two through holes C, and in the winding direction X of the pole piece, the maximum width of each through hole C is smaller than the width of the pole lug 101 . For example, at least two through holes C may be located on the busbar body 201 .

[0046] The cover plate 300 in the battery assembly 000 may be connected to a side of the busbar 200 facing away from the winding core 100 . The cover plate 300 may have an installation opening K, and the installation opening K may be connected to at least two through holes C.

[0047] In this case, since the maximum width of each through hole C in the busbar 200 is smaller than the width of the pole lug 101 in the winding direction X of the pole piece, the busbar 200 can tightly press the pole lug 101a, effectively preventing one of the multiple pole lugs from warping out of the through hole C of the busbar 200, thereby improving the reliability of the battery 000.

[0048] For examples, please refer to Figure 5 , Figure 51 is a schematic diagram of another winding core provided by the present application. The number of pole pieces 102 in the winding core 100 may be two, namely a first pole piece 102a and a second pole piece 102b; wherein the pole lug connected to the first pole piece 102a is the first pole lug 101a, and the pole lug connected to the second pole piece 102b is the second pole lug 101b.

[0049] Here, one of the first electrode sheet 102a and the second electrode sheet 102b is a positive electrode sheet in the winding core 102, and one of the first electrode sheet 102a and the second electrode sheet 102b is a negative electrode sheet in the winding core 102. The embodiment of the present application is schematically described by taking the first electrode sheet 102a as a positive electrode sheet and the second electrode sheet 102b as a negative electrode sheet as an example.

[0050] The winding core 102 may also include: a diaphragm 102c located between the first pole piece 102a and the second pole piece 102b, and the diaphragm 102c can ensure that the first pole piece 102a and the second pole piece 102b will not short-circuit. It should be noted that the stacked first pole piece 102a and the second pole piece 102b, and the diaphragm 102c located therebetween can be wound together to form the winding core 102. Here, the multiple first pole tabs 101a connected to the first pole piece 102a can be evenly arranged at one end of the winding core 102; the multiple second pole tabs 101b connected to the second pole piece 102b can be evenly arranged at the other end of the winding core 102.

[0051] In this case, there are two busbars 200 in the battery assembly 000, namely, a first busbar 210 and a second busbar 220. The first busbar 210 is welded to at least a portion of the first pole tab 101a after bending, so that the first busbar 210 can be electrically connected to the first pole piece 102a through multiple first pole tabs 101a; the second busbar 220 is welded to at least a portion of the second pole tab 101b after bending, so that the second busbar 220 can be electrically connected to the second pole piece 102b through multiple second pole tabs 101b.

[0052] The cover plate 300 in the battery assembly 000 may include: a first cover plate 301 and a second cover plate 302. The first cover plate 301 may be located on the side of the first busbar 210 away from the winding core 100, and the installation opening K on the first cover plate 301 may be used to inject electrolyte; the second cover plate 302 may be located on the side of the second busbar 220 away from the winding core 100, and the installation opening K on the second cover plate 302 may be used to install an explosion-proof valve.

[0053] In the embodiment of the present application, since the maximum width of each through hole C in the first busbar 210 is smaller than the width of the first pole lug 101a in the winding direction X of the first pole sheet 101a, the first busbar 210 can tightly press the first pole lug 101a, effectively preventing a pole lug among the multiple first pole lugs 101a from tilting out of the through hole C of the first busbar 210, avoiding the first pole lug 101a from obstructing the electrolyte flow path, ensuring uniform infiltration of the electrolyte, and improving the reliability of the battery 000.

[0054] Similarly, since the maximum width of each through hole C in the second busbar 220 is smaller than the width of the second pole tab 101b in the winding direction X of the second pole piece 101b, the second busbar 220 can tightly press the second pole tab 101b to prevent a pole tab among the plurality of second pole tabs 101b from tilting out of the through hole C of the second busbar 220. In this way, the abnormal opening caused by the second pole tab 101b accidentally touching the explosion-proof valve is avoided, and the reliability of the battery is enhanced.

[0055] In addition, since at least two through holes C are provided, even if the maximum width of each through hole C is smaller than the width of the second pole ear 101b, it will not affect the overall pressure relief area of ​​the battery, so that the excess gas generated by the battery failure can still be smoothly discharged through the at least two through holes C and the explosion-proof valve at the installation opening K to ensure that the normal pressure relief function of the explosion-proof valve is not affected, thereby further enhancing the safety and reliability of the battery.

[0056] In summary, the embodiment of the present application provides a battery assembly, including: a winding core, a busbar, and a cover plate. Since the maximum width of each through hole in the busbar is smaller than the width of the pole ear in the winding direction of the pole piece. Therefore, the busbar can be tightly pressed together with the pole ear, effectively preventing one of the multiple pole ears from tilting out of the through hole of the busbar, thereby improving the reliability of the battery. For example, in the case where the busbar is in the first busbar position, the first busbar can tightly press the first pole ear, effectively preventing one of the multiple first pole ears from tilting out of the through hole of the first busbar, avoiding the first pole ear from obstructing the electrolyte flow path, ensuring uniform infiltration of the electrolyte, and improving the reliability of the battery. In the case where the busbar is in the second busbar position, the second busbar can tightly press the second pole ear, preventing one of the multiple second pole ears from tilting out of the through hole of the second busbar. In this way, the abnormal opening caused by the second pole ear accidentally touching the explosion-proof valve is avoided, and the reliability of the battery is enhanced. In addition, since at least two through holes are provided, even if the maximum width of each through hole is smaller than the width of the second pole ear, it will not affect the overall pressure relief area of ​​the battery, so that the excess gas generated by the battery failure can still be smoothly discharged through the at least two through holes and the explosion-proof valve at the installation opening to ensure that the normal pressure relief function of the explosion-proof valve is not affected, thereby further enhancing the safety and reliability of the battery.

[0057] In the examples of this application, please refer to Figure 6 , Figure 6 1 is a schematic diagram of another structure of a busbar and a cover plate before installation provided by an embodiment of the present application. Each through hole C in the busbar 200 may include: a connected rectangular area C1 and a fan-shaped area C2, wherein the rectangular area C1 is closer to the outer boundary of the busbar 200 than the fan-shaped area C2.

[0058] In the winding direction X of the pole piece, the maximum width of the through hole C in the busbar 200 is the width of the rectangular area C1.

[0059] In this case, since the maximum width of the through hole C in the busbar 200 is the width of the rectangular area C1, and the maximum width of each through hole C in the busbar 200 is smaller than the width of the pole ear 101, the busbar 200 can press the pole ear 101 tightly, effectively preventing the pole ear 101 from tilting out of the rectangular area C1 on the busbar 200, thereby avoiding abnormal triggering of the explosion-proof valve by the pole ear 101 and preventing abnormal opening of the explosion-proof valve, thereby improving the overall safety and reliability of the battery.

[0060] Optional, please refer to Figure 7 , Figure 7 It is a schematic diagram of another structure of a busbar and a cover plate before installation provided by an embodiment of the present application. When there are two through holes C in the busbar 200 , the busbar 200 may further include: a support bar D located between the two through holes C.

[0061] The two through holes C are symmetrically distributed on both sides of the center line of the support bar D.

[0062] In this case, the tab 101 can be tightly pressed by the support bar D, effectively preventing the tab 101 from tilting out of the through hole C on the busbar 200, thereby avoiding abnormal triggering of the explosion-proof valve by the tab 101 and preventing abnormal opening of the explosion-proof valve, thereby improving the overall safety and reliability of the battery. In addition, by symmetrically distributing the two through holes C on both sides of the support bar D, the overall layout is more compact and beautiful.

[0063] In the embodiments of the present application, Figure 7 As shown, the diameter of the circle where the sector area C2 in the through hole C is located is equal to the sum of the width d1 of the two rectangular areas C1 in the two through holes C and the width d2 of the support bar D. For example, the diameter of the circle where the sector area C2 is located can be 4.5 mm, the width of the rectangular area C1 can be 1.85 mm, and the width of the support bar D can be 0.8 mm.

[0064] Optionally, in the same through hole C, the distance between the side of the rectangular area C1 away from the sector-shaped area C2 and the outer boundary of the bus tray 200 is greater than 0. That is, the rectangular area C1 does not extend to the outermost edge of the bus tray 200. For example, the distance between the side of the rectangular area C1 away from the sector-shaped area C2 and the outer boundary of the bus tray 200 ranges from 0.5 mm to 1.5 mm. For example, the distance between the side of the rectangular area C1 away from the sector-shaped area C2 and the outer boundary of the bus tray 200 is 1 mm.

[0065] In this case, by maintaining a certain distance between the rectangular area C1 and the outer boundary of the busbar 200, it is more difficult for the tab 101 to be lifted off the edge of the busbar 200, reducing the risk of the tab 101 being bent, thereby reducing the probability of the tab 101 accidentally triggering the explosion-proof valve, and significantly improving the reliability of the battery. In addition, maintaining a certain distance between the rectangular area C1 and the outer boundary of the busbar 200 can enhance the mechanical strength of the edge of the busbar 200, prevent rupture or deformation under external pressure or impact, and improve the overall durability and reliability of the busbar 200.

[0066] In the embodiment of the present application, the orthographic projections of at least two through holes C in the busbar 200 on the end surface of the winding core 100 are located within the orthographic projections of the mounting opening K in the cover plate 300 on the end surface of the winding core 100 .

[0067] This allows excess gas generated by battery failure to be discharged more smoothly through at least two through holes C and the explosion-proof valve at the installation opening K, reduces the resistance that may be encountered when the gas is discharged, and reduces the response time of the explosion-proof valve to ensure timely pressure relief, thereby further enhancing the safety and reliability of the battery.

[0068] It should be noted that the above embodiments all take the busbar 200 as the second busbar as an example, and schematically illustrate the shape and size of the through hole C provided on the busbar 200. Here, the shape and size of the through hole provided on the first busbar are also the same as the shape and size of the through hole on the second busbar, which will not be described in detail here.

[0069] In summary, the embodiment of the present application provides a battery assembly, including: a winding core, a busbar, and a cover plate. Since the maximum width of each through hole in the busbar is smaller than the width of the pole ear in the winding direction of the pole piece. Therefore, the busbar can be tightly pressed together with the pole ear, effectively preventing one of the multiple pole ears from tilting out of the through hole of the busbar, thereby improving the reliability of the battery. For example, in the case where the busbar is in the first busbar position, the first busbar can tightly press the first pole ear, effectively preventing one of the multiple first pole ears from tilting out of the through hole of the first busbar, avoiding the first pole ear from obstructing the electrolyte flow path, ensuring uniform infiltration of the electrolyte, and improving the reliability of the battery. In the case where the busbar is in the second busbar position, the second busbar can tightly press the second pole ear, preventing one of the multiple second pole ears from tilting out of the through hole of the second busbar. In this way, the abnormal opening caused by the second pole ear accidentally touching the explosion-proof valve is avoided, and the reliability of the battery is enhanced. In addition, since at least two through holes are provided, even if the maximum width of each through hole is smaller than the width of the second pole ear, it will not affect the overall pressure relief area of ​​the battery, so that the excess gas generated by the battery failure can still be smoothly discharged through the at least two through holes and the explosion-proof valve at the installation opening to ensure that the normal pressure relief function of the explosion-proof valve is not affected, thereby further enhancing the safety and reliability of the battery.

[0070] In the related art, after multiple tabs are bent in the direction toward the central axis of the core, the number of tab layers from the outer ring to the inner ring of the core gradually decreases. This results in the tabs on the inner side of the core being easily exposed to excessive welding heat input during laser welding, causing the diaphragm in the core to be burned by the heat, which may lead to direct contact between the positive and negative electrodes in the core, resulting in a short circuit risk.

[0071] To this end, the present application embodiment provides a welding method. Please refer to Figure 8 and Fig. 9 , Figure 8 is a welding power waveform diagram provided in an embodiment of the present application, Fig. 9 is another welding power waveform diagram provided in the embodiment of the present application. In the welding process of the busbar 200 and at least a portion of the bent tab 101, when welding from the inner ring to the outer ring of the winding core 100, the following can be used: Fig. 9The slow-rise waveform welding shown. By gradually increasing the welding power, it is ensured that the inner ring pole ear receives a lower heat input in the initial stage. As the welding process gradually increases the power, damage to the diaphragm (not shown) in the core 100 caused by excessive heat in the initial stage is avoided. When welding from the outer ring to the inner ring, slow-fall waveform welding can be used. By gradually reducing the welding power, it is ensured that the outer ring pole ear is welded at a higher power, while the inner ring pole ear is welded at a lower power, thereby effectively controlling the heat input of the inner ring pole ear and preventing the occurrence of scalding of the diaphragm in the core 100. In this way, through this control of the slow rise or slow fall of the welding power, effective management of the heat input of the inner ring pole ear 101 of the core 100 is achieved, and the risk of short circuit of the inner ring pole ear 101 is significantly reduced. In this way, not only the welding quality is improved, but also the safety and reliability of the battery are enhanced.

[0072] The embodiment of the present application further provides a battery module, which may include: a plurality of connected battery assemblies 000, wherein the battery assembly 000 is any of the battery assemblies 000 described above.

[0073] An embodiment of the present application also provides a vehicle, which may include: a battery module, wherein the battery module is the battery module mentioned above.

[0074] In the present application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "plurality" refers to two or more than two, unless otherwise clearly defined.

[0075] The above description is only an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A battery assembly, characterized in that: include: A winding core (100), a busbar (200) and a cover plate (300); The winding core (100) comprises: a pole piece wound as a whole, and a plurality of pole ears (101) connected to one side of the pole piece, wherein the plurality of pole ears (101) can be bent in a direction toward the central axis of the winding core (100); The busbar (200) is located at one end of the winding core (100), and the busbar (200) is welded to at least a portion of the bent pole lug (101); the busbar (200) has at least two through holes (C), and in the winding direction of the pole piece, the maximum width of each through hole (C) is smaller than the width of the pole lug (101); The cover plate (300) is connected to a side of the busbar (200) facing away from the winding core (100), and the cover plate (300) has a mounting opening (K), and the mounting opening (K) is connected to the at least two through holes (C).

2. The battery assembly according to claim 1, characterized in that: Each of the through holes (C) comprises: a connected rectangular area (C1) and a fan-shaped area (C2), wherein the rectangular area (C1) is closer to the outer boundary of the busbar (200) than the fan-shaped area (C2); Wherein, in the winding direction of the pole piece, the maximum width of the through hole (C) is the width of the rectangular area (C1).

3. The battery assembly according to claim 2, characterized in that: When the number of the through holes (C) in the busbar (200) is two, the busbar (200) further comprises: a support bar (D) located between the two through holes (C); Wherein, the two through holes (C) are symmetrically distributed on both sides of the center line of the support bar (D).

4. The battery assembly according to claim 3, characterized in that: The diameter of the circle where the sector-shaped area (C2) is located is equal to the sum of the widths of the two rectangular areas (C1) in the two through holes (C) and the width of the support bar (D).

5. The battery assembly according to any one of claims 1 to 4, characterized in that: In the same through hole (C), the distance between the side of the rectangular area (C1) facing away from the fan-shaped area (C2) and the outer boundary of the busbar (200) is greater than 0.

6. The battery assembly according to any one of claims 1 to 4, characterized in that: The orthographic projections of the at least two through holes (C) on the end surface of the winding core (100) are located within the orthographic projection of the mounting opening (K) in the cover plate (300) on the end surface of the winding core (100).

7. The battery assembly according to any one of claims 1 to 4, characterized in that: The busbar (200) comprises: a busbar body (201) and a connecting portion (202) connected to each other; the at least two through holes (C) are located on the busbar body (201), and the cover plate (300) is connected to the connecting portion (202).

8. The battery assembly according to any one of claims 1 to 4, characterized in that: The number of the pole pieces is two, namely a first pole piece and a second pole piece; the pole lug connected to the first pole piece is a first pole lug, and the pole lug connected to the second pole piece is a second pole lug, and a plurality of the first pole lugs and a plurality of the second pole lugs are respectively distributed at two ends of the winding core (100); The number of the busbars (200) is two, namely a first busbar (210) and a second busbar (220); the first busbar (210) is welded to at least a portion of the first pole tab after being bent, and the second busbar (220) is welded to at least a portion of the second pole tab after being bent.

9. The battery assembly according to claim 8, characterized in that: The cover plate (300) comprises: a first cover plate (301) and a second cover plate (302); the first cover plate (301) is located on a side of the first busbar (210) away from the winding core (100); and the installation opening (K) on the first cover plate (301) is used for injecting electrolyte; the second cover plate (302) is located on a side of the second busbar (220) away from the winding core (100); and the installation opening (K) on the second cover plate (302) is used for installing an explosion-proof valve.

10. A battery module, characterized in that: include: A plurality of connected battery assemblies, wherein the battery assemblies are the battery assemblies described in any one of claims 1-9.

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