Secondary battery and battery pack

Abstract

The secondary battery comprises at least one electrode assembly main body, a plurality of layers of tabs are arranged on each electrode assembly main body, the plurality of layers of tabs are folded to form a tab group, the tab group comprises a tab bending part and a tab root part, the tab root part is connected with the electrode assembly main body, the tab root part is triangular, and the tab bending part is connected with the tab bending part. The tab bending part is bent relative to the tab root part; the tab bending part comprises a tab connecting part, and the distance between the initial position, close to the tab root part, of the tab connecting part and the initial position, close to the tab root part, of the tab bending part is 0.5-5 mm; and the current collecting component is connected with the tab connecting part. According to the utility model, the stability of the state of the tabs can be improved, the tabs cannot be inserted into the pole pieces in a redundant sinking manner, and the safety of the secondary battery is improved.

Description

Technical Field

[0001] This utility model mainly relates to the field of battery technology, specifically to a secondary battery and a battery pack having the secondary battery. Background Technology

[0002] The battery structure includes components such as the electrode assembly body, current collector, and top cover. The electrode assembly body has tabs, and the top cover has terminals. Typically, during battery manufacturing, the tabs are first connected to the current collector using ultrasonic welding, and then the current collector is connected to the terminals on the top cover using laser welding; alternatively, the tabs themselves can be ultrasonically welded first, and then connected to the terminals on the top cover using laser welding. After these welding steps are completed, multiple electrode assembly bodies can be joined together, during which the tabs are bent.

[0003] Whether it's a single electrode assembly or multiple electrode assemblies, the tabs are typically in an "S" shape or a near-"S" shape, a "C" shape, or a near-"Z" shape. Potential defects or problems with these tab shapes and states include: 1. Uncontrollable tab state, poor consistency, poor stability, and poor vibration and shock resistance; 2. Inconsistent tightness of the tabs between inner and outer layers, resulting in inconsistent and unequal stress states. The tabs between inner and outer layers may compress each other, leading to tab splitting. Loose tabs are prone to excessive sinking and insertion into the electrode plate, causing a short circuit in the electrode assembly, while taut tabs are prone to breakage; 3. Tabs are generally too long, with significant misalignment at the top, making them more prone to excessive sinking.

[0004] Currently, insulating support plates or insulating brackets are added to the bottom of the electrode tab to support it, but the stability of the electrode tab is still not good. The existing method increases costs and may still have the problem of redundant electrode tab sinking and inserting electrode plates. Utility Model Content

[0005] The technical problem to be solved by this application is to provide a secondary battery that can improve the stability of the tab state, prevent the tab from redundantly sinking into the electrode plate, and improve the safety of the secondary battery.

[0006] The technical solution adopted in this application to solve the above-mentioned technical problems is a secondary battery, comprising: at least one electrode assembly body, each electrode assembly body having multiple layers of tabs, the multiple layers of tabs being gathered to form a tab group, the tab group including a tab bending portion and a tab root portion, the tab root portion being connected to the electrode assembly body, the tab root portion being triangular, and the tab bending portion being bent relative to the tab root portion; the tab bending portion including a tab connecting portion, the distance between the starting position of the tab connecting portion near the tab root portion and the starting position of the tab bending portion near the tab root portion being 0.5-5mm; and a current collector component connected to the tab connecting portion.

[0007] In one embodiment of this application, multiple layers of electrodes are centrally converged to form an electrode group, with the base of the electrodes forming an isosceles triangle.

[0008] In one embodiment of this application, the base angle α between the base of the tab and the body of the electrode assembly is in the range of 5°≤α≤85°.

[0009] In one embodiment of this application, the electrode assembly body has an electrode assembly body thickness T, and the electrode tab assembly has an outer electrode tab. Along the thickness direction of the electrode assembly body, there is a first distance L between the junction of the outer electrode tab and the electrode assembly body and the starting position of the electrode tab connection portion. The relationship between the first distance L and the electrode assembly body thickness T satisfies:

[0010] In one embodiment of this application, the electrode assembly body has an electrode assembly body thickness T. Along the thickness direction of the electrode assembly body, there is a second distance H between the side of the electrode assembly body near the tab group and the retracted position of the tab group. The relationship between the second distance H and the electrode assembly body thickness T satisfies:

[0011]

[0012] In one embodiment of this application, the current collector includes a first surface and a second surface opposite to each other, and the tab connection portion is connected to the first surface; or the tab connection portion is connected to the second surface.

[0013] In one embodiment of this application, the current collector includes a first surface and a second surface opposite to each other, a portion of the tab connection is connected to the first surface, and another portion of the tab connection is connected to the second surface.

[0014] In one embodiment of this application, the secondary battery further includes a top cover, on which an electrode post is disposed, and a current collector includes a current collector connecting part, which is connected to the electrode post, and the current collector is located between the electrode assembly body and the top cover.

[0015] In one embodiment of this application, the secondary battery further includes an insulating element located between the current collector and the top cover.

[0016] To address the aforementioned technical problems, this application also proposes a battery pack comprising at least one secondary battery as described above.

[0017] The technical solution of this application forms an electrode assembly by gathering the tabs together. The base of the tabs in the assembly is designed as a triangle. This design minimizes differences in tightness and stress between the inner and outer layers of tabs, preventing mutual compression and reducing the likelihood of tab splitting or breakage. The tabs remain stable and controllable, improving their consistency, stability, and vibration and shock resistance. The tabs are not redundant or sink into the electrode plates, preventing short circuits in the electrode assembly and enhancing the safety of the secondary battery. Furthermore, by setting the distance between the starting position of the tab connection near the base of the tab and the starting position of the tab bend near the base of the tab (0.5-5mm), the tab connection for welding is positioned close to the base of the tab. This reduces the tab length and the redundancy on both sides of the weld, fundamentally preventing tab redundancy and sinking, thus improving the safety of the electrode assembly. This application can reduce the production cost of secondary batteries. Attached Figure Description

[0018] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings, wherein:

[0019] Figure 1 This is a schematic diagram of the structure of the multi-layer tabs of the electrode assembly body after being folded up in one embodiment of this application;

[0020] Figure 2 This is a schematic diagram of the connection between the tab assembly and the current collector in one embodiment of this application;

[0021] Figure 3 This is a cross-sectional view of the connection between the tab assembly and the current collector in one embodiment of this application;

[0022] Figure 4 This is a schematic diagram of the connection between the flow collection component and the top cover in one embodiment of this application;

[0023] Figure 5 This is a cross-sectional view of the connection between the flow collector and the top cover in one embodiment of this application;

[0024] Figure 6 This is a schematic diagram of the structure of a secondary battery according to an embodiment of this application;

[0025] Figure 7 This is a schematic diagram of the structure of a secondary battery according to another embodiment of this application;

[0026] Figure 8 This is a schematic diagram of the structure of a secondary battery according to another embodiment of this application.

[0027] Explanation of reference numerals in the accompanying drawings for specific embodiments:

[0028] 1. Electrode assembly body; 11. Tab; 111. Tab root; 112. Tab bend; 1121. Tab connection; 1122. Starting position of tab connection; 12. Tab group; 121. Closed position of tab group; 2. Current collector; 21. Current collector connection; 201. First surface; 202. Second surface; 3. Top cover; 31. Post; 4. Insulating component; α. Bottom angle; T. Electrode assembly body thickness; L. First distance; H. Second distance. Detailed Implementation

[0029] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein, and therefore this application is not limited to the specific embodiments disclosed below.

[0031] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0032] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0033] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0034] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0035] The embodiments of this application are described below based on the accompanying drawings. However, the embodiments shown below are examples of secondary batteries and battery packs used to embody the technical concept of this application, and the secondary batteries and battery packs of this application are not specifically defined as follows. Furthermore, in order to facilitate understanding of the scope of the claims, the components corresponding to the components shown in the embodiments are assigned numbers to the components shown in the "Claims" and "Utility Model Content" columns. However, the components shown in the claims are not intended to be specific to the components of the embodiments. In particular, the dimensions, materials, shapes, and relative arrangements of the constituent components described in the embodiments are not intended to limit the scope of this application unless specifically stated, but are merely illustrative examples.

[0036] However, the dimensions or positional relationships of the components shown in the accompanying drawings are sometimes exaggerated for clarity. Therefore, in the following description, detailed descriptions of the same names and symbols representing the same or homogeneous components are appropriately omitted. Furthermore, the elements constituting this application may be multiple elements composed of the same components, thus allowing one component to function as multiple elements; conversely, multiple components may share the function of one component. Additionally, the content described in some embodiments and implementations can be applied to other embodiments and implementations. Furthermore, in this specification, "upper" is not limited to the case of being formed in contact with an upper surface, but also includes the case of being formed separately on top, and also includes the meaning of an intermediate layer between layers.

[0037] This application proposes a secondary battery that can be applied in scenarios such as vehicles and energy storage systems.

[0038] refer to Figure 6-8 As shown, the secondary battery includes: at least one electrode assembly body 1, each electrode assembly body 1 having multiple layers of tabs 11, the multiple layers of tabs 11 being gathered to form a tab assembly 12, the tab assembly 12 including a tab bending portion 112 and a tab root portion 111, the tab root portion 111 being connected to the electrode assembly body 1, the tab root portion 111 being triangular, and the tab bending portion 112 being bent relative to the tab root portion 111; the tab bending portion 112 including a tab connecting portion 1121 (e.g., Figure 7 (The portion shown by the long black solid line) The tab connection portion 1121 is close to the tab root 111; the distance between the starting position of the tab connection portion 1121 near the tab root 111 and the starting position of the tab bend portion 112 near the tab root 111 (as shown in the figure) Figure 7 The distance D, marked with a short solid black line, is 0.5-5 mm. The current collector 2 is connected to the electrode connecting part 1121. Exemplarily, the distance D can be set to 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm, with a preferred range of 1-3 mm. This application does not limit the setting of the distance D. It should be noted that the triangle defined in this application, due to the thickness of the electrode 11, does not have a strictly point-like vertex.

[0039] Figure 1 This is a schematic diagram of the structure of the multi-layered tabs of the electrode assembly body after being folded up in one embodiment of this application. Figure 2 This is a schematic diagram of the connection between the electrode assembly and the current collector in one embodiment of this application. Figure 3 This is a cross-sectional view of the connection between the electrode assembly and the current collector in one embodiment of this application. For example, refer to... Figures 1 to 3 As shown, Figure 1A single electrode assembly is shown, with tabs 11 connected to the electrode assembly body 1. The base 111 of the tab group 12 formed by the multiple tabs 11 being gathered together is triangular. Figure 2 and Figure 3 The diagram shows an intermediate state in which two electrode assemblies are assembled into a secondary battery. The two electrode assemblies are lying flat and have not yet been joined together. The tab assembly 12 is welded to the current collector 2 via the tab connector 1121.

[0040] Figure 4 This is a schematic diagram of the connection between the flow collection component and the top cover in one embodiment of this application. Figure 5 This is a cross-sectional view of the connection between the flow collector and the top cover in one embodiment of this application. Figure 4 and Figure 5 These are all intermediate states in battery assembly. (Reference) Figure 4 and Figure 5 As shown, in some embodiments, the secondary battery further includes a top cover 3, on which an electrode post 31 is disposed. A current collector 2 includes a current collector connecting portion 21, which is connected to the electrode post 31. The current collector 2 is located between the electrode assembly body 1 and the top cover 3. Exemplarily, the current collector 2 is welded to the top cover 3. The current collector connecting portion 21 can be configured as follows: Figure 4 As shown in the circular shape, this application does not limit the shape of the connecting part 21 of the current collection component.

[0041] This document describes the assembly method of the secondary battery in this application, that is, the process of assembling the secondary battery cells. Figure 5 This shows the state of the secondary battery when the cells are not reassembled. Figure 6 The image shows the state of the secondary battery after the cells are combined. Figure 5 and Figure 6 The embodiments all show two electrode assembly bodies 1.

[0042] For example, refer to Figure 5 As shown, during the core assembly process, the electrode assembly body 1 is first laid flat. The bent portion 112 of the multi-layer tabs 11, formed by folding them together, is placed above the current collector 2 and welded to it via the tab connection portion 1121. Next, the electrode assembly body 1 and the current collector 2 are placed together above the pole post 31 of the top cover 3, and the current collector 2 is welded to the pole post 31, thus achieving the connection between the electrode assembly body 1 and the top cover 3. (Reference) Figure 6 As shown, the electrode assembly body 1 is rotated 90° and multiple electrode assembly bodies 1 are joined together, so that the current collector 2 is located between the electrode assembly body 1 and the top cover 3. During this process, the electrode assembly body 1 is folded in half, and the tab assembly 12 is bent to form the tab bend 112. The folded tab root 111 is an isosceles triangle. The tab root 111 is located between the current collector 2 and the electrode assembly body 1, and the tab root 111 is located below the current collector 2.

[0043] In other embodiments, more electrode assembly bodies 1 can be cored together. The number of electrode assembly bodies 1 can be 3, 4 or even more. The distribution position of the tabs 11 on the electrode assembly body 1 can be set as needed. This application does not limit the number of electrode assembly bodies 1 or the distribution position of the tabs 11.

[0044] The technical solution of this application forms an electrode assembly 12 by gathering the tabs 11. The root 111 of the tab assembly 12 is designed as a triangle. This design makes the difference in tightness and stress state between the inner and outer layers of tabs 11 small, and the tabs 11 between the inner and outer layers will not squeeze each other. The tabs 11 are less likely to split or break, and the state of the tabs 11 is stable and controllable, which improves the consistency, stability and vibration and shock resistance of the tabs 11. The tabs 11 will not be redundant or sink into the electrode plate, and the electrode assembly will not short-circuit, thus improving the safety of the secondary battery. The distance between the starting position of the tab connection part 1121 near the root 111 and the starting position of the tab bending part 112 near the root 111 is 0.5-5mm. That is, by setting the tab connection part 1121 used for welding to be close to the root 111, the length of the tab can be reduced and the redundancy of the tabs on both sides of the tab welding can be reduced, which fundamentally avoids the redundancy and sinking of the tabs and improves the safety of the electrode assembly. This application can reduce the production cost of secondary batteries.

[0045] refer to Figure 6 As shown, in some embodiments, the multilayer tabs 11 converge centrally to form a tab assembly 12, with the tab root 111 forming an isosceles triangle. Exemplarily, this application sets the state of the tab root 111 to an isosceles triangle, thereby making the state of the tab 11 stable and controllable, fundamentally solving the problems of tab redundancy and sagging that may lead to short circuits in the electrode assembly, and improving the safety of the electrode assembly.

[0046] In some embodiments, the base angle α between the electrode root 111 and the electrode assembly body 1 is 5° ≤ α ≤ 85°, and exemplary base angle α can be 5°, 15°, 30°, 45°, 60°, 75°, or 85°. (Reference) Figure 6 As shown, exemplarily, the base angle α corresponds to the base angle of the tab root 111. In practical applications, when the base angle α is less than 5°, the tab root 111 is prone to sinking after being squeezed, which may cause it to contact the electrode assembly body 1 and cause a short circuit; when the base angle α is greater than 85°, the length of the tab root 111 will be relatively long, thus the tab root 111 is prone to redundant sinking. This application can avoid the tab root sinking by setting the range of the base angle α, thereby improving the safety of the electrode assembly.

[0047] refer to Figure 6As shown, in some embodiments, the electrode assembly body 1 has an electrode assembly body thickness T, and the tab assembly 12 has an outer tab (i.e., a tab 11 away from the centerline of the electrode assembly body 1). Along the thickness direction of the electrode assembly body (i.e., the direction parallel to the electrode assembly body thickness T), there is a first distance L between the junction of the outer tab and the electrode assembly body 1 and the starting position 1122 of the tab connection portion. The relationship between the first distance L and the electrode assembly body thickness T satisfies: For example, the thickness T of the electrode assembly body can be used as a reference. arrive To set the starting position 1122 of the electrode connection part, preferably, This application determines the position of the electrode welding area by setting the starting position 1122 of the electrode connection part. This setting can reduce the length of the electrode and reduce the electrode redundancy on both sides of the electrode welding.

[0048] refer to Figure 3 As shown, in some embodiments, the electrode assembly body 1 has an electrode assembly body thickness T. Along the thickness direction of the electrode assembly body (i.e., the direction parallel to the electrode assembly body thickness T), there is a second distance H between the side of the electrode assembly body 1 near the root 111 of the tab and the retracted position 121 of the tab assembly 12. The relationship between the second distance H and the electrode assembly body thickness T satisfies: For example, such as Figure 3 As shown, when the electrode assembly body 1 is in a flat position, the second distance H is equivalent to the height from the folded position 121 of the tab assembly to the bottom of the electrode assembly body 1. By designing the relationship between the second distance H and the thickness T of the electrode assembly body, this application can make the root 111 of the tab formed after the multi-layer tabs 11 are folded together form an isosceles triangle, which can make the state of the tabs 11 more stable and prevent the tabs from sinking.

[0049] refer to Figure 6 and Figure 7 As shown, in some embodiments, the current collector 2 includes a first surface 201 and a second surface 202 facing each other, and the tab connection portion 1121 is connected to the first surface 201 (e.g., Figure 6 (as shown); or the tab connection 1121 is connected to the second surface 202 (as shown). Figure 7 (As shown).

[0050] Figure 8 This is a schematic diagram of the structure of a secondary battery according to another embodiment of this application. (Reference) Figure 8 As shown, in some embodiments, a portion of the tab connection 1121 is connected to the first surface 201, and another portion of the tab connection 1121 is connected to the second surface 202.

[0051] For example, in practical applications, the connection method between the tab connection portion 1121 on the main body 1 of different electrode assemblies and the current collector 2 can be adopted as follows: Figures 6 to 8 The electrode assembly body 1 can be configured in any way, for example, the tab connection portion 1121 of one electrode assembly body 1 is connected to the first surface 201, and the tab connection portion 1121 of the other electrode assembly body 1 is connected to the second surface 202. Or as... Figure 6 As shown, the tabs 11 of all electrode assembly bodies 1 can be located entirely below the current collector 2; as Figure 7 As shown, the tabs 11 of all electrode assembly bodies 1 can be located above the current collector 2; as Figure 8 As shown, the tabs 11 of all electrode assembly bodies 1 can be located partly below the current collector 2 and partly above the current collector 2. This application does not limit the connection method between the tab connection portion 1121 and the current collector 2.

[0052] refer to Figure 6 As shown, in some embodiments, the secondary battery further includes an insulating member 4, which is located between the current collector 2 and the top cover 3. Exemplarily, the insulating member 4 may be a lower plastic component. Figure 6 The insulating element 4 shown in the figure has protrusions on both sides. By setting the insulating element 4, the top cover 3 and the current collector 2 can be physically insulated, which can effectively isolate the electrical connection between the top cover 3 and the current collector 2, avoid short circuit, and thus improve the safety and reliability of the secondary battery.

[0053] The embodiments of this application also disclose a battery pack (not shown), including at least one secondary battery as described above. Exemplarily, when the battery pack of this application is applied in scenarios such as vehicles and energy storage systems, the tabs do not redundantly sink down to insert into the electrode plates, thus improving the safety of the battery pack.

[0054] While the foregoing disclosure has discussed various examples of utility model embodiments that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the spirit and scope of the embodiments of this application. For example, although the system components described above can be implemented by hardware devices, they can also be implemented solely by software solutions, such as installing the described system on existing servers or mobile devices.

[0055] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the utility model, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the present application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0056] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of scope in some embodiments of this application are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0057] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the essential spirit of this application will fall within the scope of the claims of this application.

Claims

1. A secondary battery, characterized in that, include: At least one electrode assembly body, each electrode assembly body having multiple layers of tabs, the multiple layers of tabs being brought together to form a tab group, the tab group including a tab bending portion and a tab root portion, the tab root portion being connected to the electrode assembly body, the tab root portion being triangular, the tab bending portion being bent relative to the tab root portion; the tab bending portion including a tab connecting portion, the distance between the starting position of the tab connecting portion near the tab root portion and the starting position of the tab bending portion near the tab root portion being 0.5-5mm; The current collector is connected to the electrode connecting part.

2. The secondary battery as described in claim 1, characterized in that, The multi-layered electrodes converge in the center to form the electrode group, and the root of the electrode is an isosceles triangle.

3. The secondary battery as described in claim 1, characterized in that, The base of the electrode ear and the main body of the electrode assembly have a base angle α, and the range of the base angle α is: 5°≤α≤85°.

4. The secondary battery as described in claim 1, characterized in that, The electrode assembly body has an electrode assembly body thickness T. The electrode tab assembly has an outer electrode tab. Along the thickness direction of the electrode assembly body, there is a first distance L between the junction of the outer electrode tab and the electrode assembly body and the starting position of the electrode tab connection portion. The relationship between the first distance L and the electrode assembly body thickness T satisfies:

5. The secondary battery as described in claim 1, characterized in that, The electrode assembly body has an electrode assembly body thickness T. Along the thickness direction of the electrode assembly body, there is a second distance H between the side of the electrode assembly body near the tab group and the retracted position of the tab group. The relationship between the second distance H and the electrode assembly body thickness T satisfies:

6. The secondary battery as described in claim 1, characterized in that, The current collector includes a first surface and a second surface opposite to each other, and the electrode connecting part is connected to the first surface; or the electrode connecting part is connected to the second surface.

7. The secondary battery as described in claim 1, characterized in that, The current collector includes a first surface and a second surface opposite to each other, a portion of the tab connection is connected to the first surface, and another portion of the tab connection is connected to the second surface.

8. The secondary battery as described in claim 1, characterized in that, It also includes a top cover, on which an electrode post is provided, and the current collector includes a current collector connecting part, which is connected to the electrode post, and the current collector is located between the electrode assembly body and the top cover.

9. The secondary battery as described in claim 8, characterized in that, It also includes an insulating element located between the current collecting member and the top cover.

10. A battery pack, characterized in that, It includes at least one secondary battery as described in any one of claims 1-9.

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