Battery cell and battery pack

Abstract

The utility model relates to the technical field of batteries, and discloses a single battery and a battery pack, the single battery comprises a shell provided with a first pole; the first pole core and the second pole core are laminated in the shell; the first tab is connected with one end of the first pole core; the second tab is connected with one end of the second pole core; the first flexible connecting piece comprises a first connecting section, a second connecting section and a third connecting section which are connected, and the first connecting section and the second connecting section as well as the first connecting section and the third connecting section are arranged at angles respectively; the first connecting section is provided with a first welding printing part connected with the first pole, the second connecting section is provided with a second welding printing part connected with the first tab, and the third connecting section is provided with a third welding printing part connected with the second tab. According to the invention, the soft connecting sheet is used for replacing a hard connecting sheet to connect the pole and the tab, so that the problem that a thick connecting sheet is difficult to bend is solved.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and particularly to a battery cell and a battery pack. Background Art

[0002] In a battery, it is usually necessary to use a connecting piece as a bridge between the battery electrode core and the electrode. The existing single-layer hard connecting piece is difficult to bend, and the tab is prone to tearing during the bending process. To overcome the process problems such as bending, using a single-layer, relatively thin metal sheet can meet the requirements. Currently, large power batteries generally have high-current charging and discharging requirements, and traditional single-layer, relatively thin metal sheets cannot meet the requirements, so a relatively thick metal sheet is needed, but it is more difficult to bend a relatively thick metal sheet. Summary of the Utility Model

[0003] The purpose of this application is to provide a battery cell and a battery pack, by stacking two electrode cores and connecting the pole column and the tab through a soft connecting piece with a welding mark portion, to solve the technical problems that the hard connecting piece is difficult to bend and it is difficult to meet the high-current charging and discharging requirements of large power batteries.

[0004] To achieve the above purpose, in a first aspect, this application provides a battery cell, including: a housing provided with a first pole column; a first electrode core disposed in the housing; a second electrode core stacked with the first electrode core and disposed in the housing; a first tab connected to one end of the first electrode core; a second tab connected to one end of the second electrode core; and a first soft connecting piece, which includes a connected first connecting section, a second connecting section, and a third connecting section. One end of the first connecting section is connected to the second connecting section, the other end of the first connecting section is connected to the third connecting section, and the first connecting section is disposed at an angle with respect to the second connecting section and the third connecting section respectively; the first connecting section is provided with a first welding mark portion connected to the first pole column, the second connecting section is provided with a second welding mark portion connected to the first tab, and the third connecting section is provided with a third welding mark portion connected to the second tab.

[0005] In some embodiments, the first soft connecting piece further includes a first bending portion and a second bending portion. The first bending portion is disposed between the first connecting section and the second connecting section, and the second bending portion is disposed between the first connecting section and the third connecting section; the thicknesses of the first bending portion and the second bending portion are both less than or equal to the thickness of the first electrode core; or the thicknesses of the first bending portion and the second bending portion are both less than or equal to the thickness of the second electrode core.

[0006] In some embodiments, the housing is further provided with a second pole column; a third pole tab, connected to the other end of the first pole core, and the third pole tab has a polarity opposite to that of the first pole tab; a fourth pole tab, connected to the other end of the second pole core, and the fourth pole tab has a polarity opposite to that of the second pole tab; a second flexible connection piece, which includes a connected fourth connection section, a fifth connection section, and a sixth connection section. One end of the fourth connection section is connected to the fifth connection section, the other end of the fourth connection section is connected to the sixth connection section, and the fourth connection section is disposed at an angle with respect to both the fifth connection section and the sixth connection section. The fourth connection section is provided with a fourth welding mark portion connected to the second pole column, the fifth connection section is provided with a fifth welding mark portion connected to the third pole tab, and the sixth connection section is provided with a sixth welding mark portion connected to the fourth pole tab.

[0007] In some embodiments, the second flexible connection piece further includes a third bending portion and a fourth bending portion. The third bending portion is disposed between the fourth connection section and the fifth connection section, and the fourth bending portion is disposed between the fourth connection section and the sixth connection section. The thicknesses of both the third bending portion and the fourth bending portion are less than or equal to the thickness of the first pole core; or the thicknesses of both the third bending portion and the fourth bending portion are less than or equal to the thickness of the second pole core.

[0008] In some embodiments, the first flexible connection piece is connected to the first pole tab and the second pole tab by laser penetration welding; the second flexible connection piece is connected to the third pole tab and the fourth pole tab by laser penetration welding.

[0009] In some embodiments, the first flexible connection piece has a U-shaped structure; the second flexible connection piece has a U-shaped structure.

[0010] In some embodiments, the first flexible connection piece includes multiple metal thin sheets stacked on top of each other; the second flexible connection piece includes multiple metal thin sheets stacked on top of each other.

[0011] In some embodiments, the thickness of the metal thin sheet is 0.02 - 1 mm.

[0012] In some embodiments, the housing includes a housing body, a first top cover, and a second top cover. The first top cover and the second top cover are respectively disposed at opposite ends of the housing body, the first pole column is disposed on the first top cover, and the second pole column is disposed on the second top cover.

[0013] To achieve the above object, in a second aspect, the present application provides a battery pack, including: a box body; and the above-mentioned battery cell, the battery cell is disposed inside the box body.

[0014] The technical effect of the present application is to provide a battery cell and a battery pack, which use a flexible connecting piece to replace a rigid connecting piece to connect the pole column and the pole ear, so as to solve the problem of difficult bending of the thick connecting piece. Further, by stacking two electrode cores and realizing the connection between the pole column and the pole ear through a flexible connecting piece with a welding mark portion, the flexible connecting piece without a welding mark portion can be used as the bending position, so that there is no gap between the layers of the flexible connecting piece, and the connection between the pole ear and the flexible connecting piece is not limited by the laser welding process, and the thickness of the electrode core can be increased to meet the large current charging and discharging requirements of large power batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following will clearly show the technical solutions and other beneficial effects of the present application by describing the specific embodiments of the present application in detail with reference to the accompanying drawings.

[0016] Figure 1 It is a schematic structural diagram of a battery cell provided by an embodiment of the present application.

[0017] Figure 2 is Figure 1 an enlarged view of the first flexible connecting piece in

[0018] Figure 3 is Figure 1 a side view of the first top cover in

[0019] Figure 4 is Figure 1 an enlarged view of the second flexible connecting piece in

[0020] Figure 5 is Figure 1 a side view of the second top cover in

[0021] The reference numerals of the components in the drawings are as follows:

[0022] 1 housing; 2 first electrode core; 3 second electrode core;

[0023] 41 first pole ear; 42 third pole ear; 51 second pole ear; 52 fourth pole ear;

[0024] 61 first flexible connecting piece; 62 second flexible connecting piece;

[0025] 11 first pole column; 12 second pole column; 10 housing main body;

[0026] 13 first top cover; 14 second top cover;

[0027] 601 first connecting section; 602 second connecting section; 603 third connecting section; 604 first bending portion; 605 second bending portion; 606 fourth connecting section; 607 fifth connecting section; 608 sixth connecting section; 609 third bending portion; 610 fourth bending portion;

[0028] 611 First welding mark part; 612 Second welding mark part; 613 Third welding mark part; 614 Fourth welding mark part; 615 Fifth welding mark part; 616 Sixth welding mark part;

[0029] X First direction; Y Second direction. Detailed implementation manner

[0030] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0031] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "thickness", "upper", "lower", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0032] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, an electrical connection, or a communication with each other; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0033] Currently, when a relatively thick metal sheet is used as a connection sheet, it is difficult to bend, and it is difficult to meet the large-current charging and discharging requirements of large power batteries.

[0034] To solve the above problems, the present application provides a battery cell and a battery pack, which use a flexible or soft connecting piece to replace the hard connecting piece to connect the battery core and the electrode. Moreover, by stacking two cores and using a flexible / soft connecting piece with a welding imprint part (collectively referred to as a soft connecting piece below) to realize the connection between the pole column and the pole ear, in order to solve the technical problem that in the long-term use of the power battery, since the soft connecting piece includes multiple metal thin sheets and there are gaps between the layers of the metal thin sheets, the pole ear cannot be laser welded to the multiple metal thin sheets of the soft connecting piece, which limits the thickness of the battery cell. The following will be described in detail.

[0035] Figure 1 It is a schematic structural diagram of the battery cell provided by the embodiment of the present application.

[0036] As Figure 1 shown, a battery cell includes a housing 1, a first core 2, a second core 3, a first pole ear 41, a second pole ear 51, and a first soft connecting piece 61.

[0037] As Figure 1 shown, the housing 1 is provided with a first pole column 11. In this embodiment, the housing 1 may include a housing main body 10 and a first top cover 13. The housing main body 10 has two opposite ends in the first direction X (i.e., the length direction), and the first top cover 13 is disposed at one end of the housing main body 10. The first pole column 11 is disposed on the first top cover 13. It can be understood that the first pole column 11 and the first top cover 13 may be an integral structure or a split structure, as long as the connection between the first pole column 11 and the first top cover 13 can be achieved. The pole column and the top cover being an integral structure means that both the top cover and the pole column are made of conductive materials, which is beneficial to improving the assembly efficiency of the core inside the housing 1.

[0038] As Figure 1 shown, the second core 3 and the first core 2 are stacked and disposed inside the housing 1. Specifically, the second core 3 and the first core 2 are stacked and disposed inside the cavity of the housing main body 10.

[0039] As Figure 1 shown, the first pole ear 41 is connected to one end (left end) of the first core 2.

[0040] As Figure 1 shown, the second pole ear 51 is connected to one end (left end) of the second core 3.

[0041] Figure 2 It is Figure 1 an enlarged view of the first soft connecting piece 61 in

[0042] As Figure 1 or Figure 2As shown, the first flexible connection piece 61 includes a connected first connection segment 601, a second connection segment 602, and a third connection segment 603. One end of the first connection segment 601 is connected to the second connection segment 602, and the other end of the first connection segment 601 is connected to the third connection segment 603. The first connection segment 601 is disposed at an angle with respect to both the second connection segment 602 and the third connection segment 603. The first connection segment 601 is provided with a first welding mark portion 611 for connecting to the pole post, the second connection segment 602 is provided with a second welding mark portion 612 for connecting to the first pole tab 41, and the third connection segment 603 is provided with a third welding mark portion 613 for connecting to the second pole tab 51.

[0043] The first flexible connection piece 61 is a positive flexible connection piece. The first connection segment 601 of the first flexible connection piece 61 is connected to the first pole post 11 through the first welding mark portion 611, the second connection segment 602 is connected to the first pole tab 41 through the second welding mark portion 612, and the third connection segment 603 is connected to the second pole tab 51 through the third welding mark portion 613, so as to realize the connection of the positive ends of the two pole cores.

[0044] In this embodiment, as Figure 1 or Figure 2 shown, the first flexible connection piece 61 further includes a first bending portion 604 and a second bending portion 605. The first bending portion 604 is disposed between the first connection segment 601 and the second connection segment 602, and the second bending portion 605 is disposed between the first connection segment 601 and the third connection segment 603. By disposing the first bending portion 604 and the second bending portion 605 between the two connection segments, it is possible to avoid the bending portions from being subjected to ultrasonic welding treatment, thereby avoiding the problem that the thickness of the bent portion of the first flexible connection piece 61 is too thick and difficult to bend. Therefore, the first flexible connection piece 61 of the present application realizes the connection between the pole post and the pole tab through its own welding mark portion, thereby realizing the connection between the battery pole core and the electrode (positive electrode).

[0045] Figure 3 is Figure 1 a side view of the first top cover 13 in Figure 3 shown. As Figure 3 shown,

[0046] In this embodiment, as Figure 1 or Figure 2 shown, the first bending portion 604 of the first flexible connection piece 61 is disposed between the first connection segment 601 and the second connection segment 602, and the second bending portion 605 is disposed between the first connection segment 601 and the third connection segment 603. z

[0047] The thicknesses of the first bending portion 604 and the second bending portion 605 are both less than or equal to the thickness of the first electrode core 2 in the second direction Y. In this way, it can be ensured that the first flexible connecting piece 61 will not be torn during the bending process. Or, the thicknesses of the first bending portion 604 and the second bending portion 605 are both less than or equal to the thickness of the second electrode core 3 in the second direction Y. In this way, it can also be ensured that the first flexible connecting piece 61 will not be torn during the bending process.

[0048] As Figure 1 shown, in this embodiment, the first flexible connecting piece 61 is connected to the first tab 41 and the second tab 51 by laser penetration welding.

[0049] In this embodiment, as Figure 1 shown, the first flexible connecting piece 61 is of a U-shaped structure. Specifically, the first flexible connecting piece 61 includes multiple layers of stacked metal sheets, and the U-shaped structure is formed by bending the multiple layers of metal sheets.

[0050] In this embodiment, the thickness of each layer of metal sheet is 0.02 - 1 mm. In this way, it can be avoided that the excessive thickness of the first flexible connecting piece 61 affects its bending effect. It can be understood that the thickness (unit: mm) of the metal sheet can be any value among 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 1 or a value within the range between any two values.

[0051] In this embodiment, as Figure 1 shown, the first welding imprint portion 611, the second welding imprint portion 612 and the third welding imprint portion 613 are formed by ultrasonic welding and leveling.

[0052] In this embodiment, as Figure 1 or Figure 2As shown, multiple layers of metal thin film sheets are stacked to form an unbent first flexible connection sheet 61. According to the pre-bending position, the unbent first flexible connection sheet 61 is divided into a first connection section 601, a second connection section 602, a third connection section 603, a first bending portion 604, and a second bending portion 605. In this way, the pre-bending position of the first flexible connection sheet 61 can be defined. Moreover, a first welding mark portion 611 is defined in the first connection section 601, a second welding mark portion 612 is defined in the second connection section 602, and a third welding mark portion 613 is defined in the third connection section 603. In this way, the welding mark areas of the first flexible connection sheet 61 are defined in the corresponding areas first. When ultrasonic welding treatments are respectively performed on the first welding mark portion 611, the second welding mark portion 612, and the third welding mark portion 613, the welding mark areas can be accurately aligned. After the welding marks are completed, the welding mark positions of the multiple layers of metal thin film sheets can be leveled, and the first flexible connection sheet 61 is bent according to the design to form a U-shaped structure. In this way, the layer spacing of the first flexible connection sheet 61 can be reduced and the flatness of the welding surface can be improved, and the bending portions of the first flexible connection sheet 61 are not processed, reducing the bending force and reducing the damage to the tab.

[0053] As Figure 1 shown, the housing 1 is further provided with a second terminal 12. In this embodiment, the housing 1 may further include a second top cover 14, and the terminal may further include a second terminal 12. The housing body 10 has opposite ends in the first direction X (i.e., the length direction). The first top cover 13 and the second top cover 14 are respectively covered on the opposite ends of the housing body 10, and the second terminal 12 is disposed on the second top cover 14. It can be understood that the second terminal 12 and the second top cover 14 may be an integral structure or a split structure, as long as the connection between the second terminal 12 and the second top cover 14 can be realized. Among them, the terminal and the top cover are an integral structure, that is, the materials used for the top cover and the terminal are both conductive materials, which is beneficial to improving the assembly efficiency of the electrode core inside the housing 1.

[0054] Figure 4 is Figure 1 an enlarged view of the second flexible connection sheet 62 in

[0055] As Figure 1 and Figure 4 shown, the battery cell further includes a third tab 42, a fourth tab 52, and a second flexible connection sheet 62.

[0056] The first electrode core 2 has opposite ends in the first direction X. The third tab 42 is connected to the other end (right end) of the first electrode core 2, and the polarity of the third tab 42 is opposite to that of the first tab 41.

[0057] The second pole core 3 has two ends arranged oppositely in the first direction X. The fourth pole tab 52 is connected to the other end (right end) of the second pole core 3, and the fourth pole tab 52 has a polarity opposite to that of the second pole tab 51.

[0058] The second soft connection piece 62 includes a connected fourth connection segment 606, a fifth connection segment 607, and a sixth connection segment 608. One end of the fourth connection segment 606 is connected to the fifth connection segment 607, the other end of the fourth connection segment 606 is connected to the sixth connection segment 608, and the fourth connection segment 606 is arranged at an angle with respect to both the fifth connection segment 607 and the sixth connection segment 608; the fourth connection segment 606 is provided with a fourth welding mark portion 614 for connecting to the second pole 12, the fifth connection segment 607 is provided with a fifth welding mark portion 615 for connecting to the third pole tab 42, and the sixth connection segment 608 is provided with a sixth welding mark portion 616 for connecting to the fourth pole tab 52.

[0059] The second soft connection piece 62 is a negative - pole soft connection piece. The fourth connection segment 606 of the second soft connection piece 62 is connected to the second pole 12 through the fourth welding mark portion 614, the fifth connection segment 607 is connected to the third pole tab 42 through the fifth welding mark portion 615, and the sixth connection segment 608 is connected to the fourth pole tab 52 through the sixth welding mark portion 616, so as to realize the connection of the negative - extreme ends of the two pole cores.

[0060] Figure 5 is Figure 1 a side view of the second top cover 14 in the middle. As Figure 5 shown, Figure 5 it shows the connection relationship between the fourth welding mark portion 614 on the right side and the second pole 12.

[0061] In this embodiment, as Figure 1 and Figure 4 shown, the second soft connection piece 62 further includes a third bending portion 609 and a fourth bending portion 610. The third bending portion 609 is arranged between the fourth connection segment 606 and the fifth connection segment 607, and the fourth bending portion 610 is arranged between the fourth connection segment 606 and the sixth connection segment 608. Arranging the third bending portion 609 and the fourth bending portion 610 between the two connection segments can prevent the bending portions from being subjected to ultrasonic welding treatment, thereby avoiding the problem that the thickness at the bending place of the second soft connection piece 62 is too thick and it is difficult to bend. Therefore, the second soft connection piece 62 of the present application realizes the connection between the pole and the pole tab through its own welding mark portion, thereby realizing the connection between the battery pole core and the electrode (negative electrode).

[0062] In this embodiment, as Figure 1As shown, the thicknesses of the third bending portion 609 and the fourth bending portion 610 are both less than or equal to the thickness of the first electrode core 2. In this way, it can be ensured that the second flexible connection piece 62 will not be torn during the bending process. Or, the thicknesses of the third bending portion 609 and the fourth bending portion 610 are both less than or equal to the thickness of the second electrode core 3. In this way, it can also be ensured that the second flexible connection piece 62 will not be torn during the bending process.

[0063] As Figure 1 shown, in this embodiment, the second flexible connection piece 62 is connected to the third tab 42 and the fourth tab 52 by laser penetration welding.

[0064] In this embodiment, as Figure 1 shown, the second flexible connection piece 62 is also of a U-shaped structure. Specifically, the second flexible connection piece 62 includes multiple layers of stacked metal sheets, and the U-shaped structure is formed by bending the multiple layers of metal sheets.

[0065] In this embodiment, the thickness of each layer of metal sheet is 0.02 - 1 mm. In this way, it can be avoided that the excessive thickness of the first flexible connection piece 61 or the second flexible connection piece 62 affects their bending effect. It can be understood that the thickness (unit: mm) of the metal sheet can be any value among 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 1 or a value within the range between any two values.

[0066] In this embodiment, as Figure 1 shown, the fourth welding mark portion 614, the fifth welding mark portion 615, and the sixth welding mark portion 616 are formed by ultrasonic welding and leveling.

[0067] In this embodiment, as Figure 1As shown in the figure, multiple layers of metal thin film sheets are stacked to form an unbent second flexible connection sheet 62. According to the pre-bending positions, the unbent second flexible connection sheet 62 is divided into a fourth connection section 606, a fifth connection section 607, a sixth connection section 608, a third bending portion 609, and a fourth bending portion 610. In this way, the pre-bending positions of the second flexible connection sheet 62 can be defined. Moreover, a fourth welding mark portion 614 is defined in the fourth connection section 606, a fifth welding mark portion 615 is defined in the fifth connection section 607, and a sixth welding mark portion 616 is defined in the sixth connection section 608. In this way, the welding mark areas of the second flexible connection sheet 62 are defined in the corresponding regions. When ultrasonic welding treatments are respectively performed on the fourth welding mark portion 614, the fifth welding mark portion 615, and the sixth welding mark portion 616, each welding mark area can be accurately aligned. After the welding marks are completed, the welding mark positions of the multiple layers of metal thin film sheets can be leveled, and the second flexible connection sheet 62 is bent according to the design to form a U-shaped structure. In this way, the layer spacing of the second flexible connection sheet 62 can be reduced and the flatness of the welding surface can be improved, and the bending portions of the second flexible connection sheet 62 are not processed, reducing the bending force and reducing the damage to the tab.

[0068] Therefore, in each end of the battery cell of the present application, a flexible connection sheet with a U-shaped structure is used to connect two stacked electrode cores, and the connection between the pole column and the tab is realized through the flexible connection sheet with welding mark portions (i.e., the connection between the electrode core and the electrode (positive electrode, negative electrode)) is realized. The flexible connection sheet without welding mark portions can be used as the bending position, so that there is no gap between the layers of the flexible connection sheet, the connection between the tab and the flexible connection sheet is not restricted by the laser welding process, and the thickness of the electrode core can be increased to meet the large current charge and discharge requirements of large power batteries.

[0069] The embodiment of the present application further provides a battery pack, including: a box body; and the above-mentioned battery cell, and the battery cell is arranged in the box body. In this battery pack, two electrode cores are stacked, and the connection between the pole column and the tab is realized through the flexible connection sheet with welding mark portions. The flexible connection sheet without welding mark portions can be used as the bending position, so that there is no gap between the layers of the flexible connection sheet, the connection between the tab and the flexible connection sheet is not restricted by the laser welding process, and the thickness of the electrode core can be increased to meet the large current charge and discharge requirements of large power batteries.

[0070] In the above embodiments, the descriptions of the various embodiments have their own focuses. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0071] The above has introduced in detail a battery cell and a battery pack provided by an embodiment of the present application. Specific examples are used herein to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, characterized in that, Comprising: A housing provided with a first terminal post; A first electrode core disposed within the housing; A second electrode core stacked with the first electrode core and disposed within the housing; A first tab connected to one end of the first electrode core; A second tab connected to one end of the second electrode core; And A first flexible connection piece, which includes a connected first connection section, a second connection section, and a third connection section. One end of the first connection section is connected to the second connection section, and the other end of the first connection section is connected to the third connection section. And the first connection section is respectively disposed at an angle with the second connection section and the third connection section. The first connection section is provided with a first welding mark portion connected to the first terminal post, the second connection section is provided with a second welding mark portion connected to the first tab, and the third connection section is provided with a third welding mark portion connected to the second tab.

2. The battery cell according to claim 1, wherein The first flexible connection piece further includes a first bending portion and a second bending portion. The first bending portion is disposed between the first connection section and the second connection section, and the second bending portion is disposed between the first connection section and the third connection section; The thicknesses of the first bending portion and the second bending portion are both less than or equal to the thickness of the first electrode core; or The thicknesses of the first bending portion and the second bending portion are both less than or equal to the thickness of the second electrode core.

3. The battery cell according to claim 1, wherein Further comprising: The housing is further provided with a second terminal post; A third tab connected to the other end of the first electrode core, and the third tab has a polarity opposite to that of the first tab; A fourth tab connected to the other end of the second electrode core, and the fourth tab has a polarity opposite to that of the second tab; A second flexible connection piece, which includes a connected fourth connection section, a fifth connection section, and a sixth connection section. One end of the fourth connection section is connected to the fifth connection section, and the other end of the fourth connection section is connected to the sixth connection section. And the fourth connection section is respectively disposed at an angle with the fifth connection section and the sixth connection section. The fourth connection section is provided with a fourth welding mark portion connected to the second terminal post, the fifth connection section is provided with a fifth welding mark portion connected to the third tab, and the sixth connection section is provided with a sixth welding mark portion connected to the fourth tab.

4. The battery cell according to claim 3, wherein The second flexible connection piece further includes a third bending portion and a fourth bending portion. The third bending portion is disposed between the fourth connection section and the fifth connection section, and the fourth bending portion is disposed between the fourth connection section and the sixth connection section; The thicknesses of the third bending portion and the fourth bending portion are both less than or equal to the thickness of the first electrode core; Or The thicknesses of the third bending portion and the fourth bending portion are both less than or equal to the thickness of the second electrode core.

5. The battery cell according to claim 3, wherein The first flexible connection piece is connected to the first tab and the second tab by laser penetration welding; The second flexible connection piece is connected to the third tab and the fourth tab by laser penetration welding.

6. The battery cell according to claim 3, wherein the first flexible connection piece has a U-shaped structure; the second flexible connection piece has a U-shaped structure.

7. The battery cell according to claim 3, wherein the first flexible connection piece comprises a plurality of metal thin sheets stacked on top of each other; the second flexible connection piece comprises a plurality of metal thin sheets stacked on top of each other.

8. The battery cell according to claim 7, wherein the thickness of the metal thin sheet is 0.02 - 1 mm.

9. The battery cell according to claim 3, wherein the housing comprises a housing body, a first top cover and a second top cover, the first top cover and the second top cover are respectively disposed at opposite ends of the housing body, the first pole is disposed on the first top cover, and the second pole is disposed on the second top cover.

10. A battery pack, characterized in that, Comprising: a box body; and the battery cell according to any one of claims 1 to 9, the battery cell being disposed in the box body.

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