Secondary battery

Abstract

The utility model belongs to the technical field of batteries, and particularly relates to a secondary battery, which comprises a shell, a battery cover and a battery cover, the cover plate assembly seals the opening, and a pole is arranged on the cover plate assembly; an electrode assembly including a tab stack; the plurality of layers of tabs are mutually connected in a first area of the tab stack body in a welding manner; the pole is connected with the second area of the tab stack body in a welding manner; the center of the first area deviates by a first preset distance L4 in a first direction relative to the center of the tab stacking body; the center of the second area deviates by a second preset distance L5 in the first direction relative to the center of the first area; the welding area is shifted relative to the tab and the pre-welding area at the same time, so that the welding area can adapt to the shifting of the pole, the pre-welding area can be ensured to have a proper size, and the undesirable phenomena of tearing, loosening, short circuit and the like of the tab are avoided.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, specifically relating to a secondary battery. Background Technology

[0002] Battery tabs and terminals are typically connected by welding. This involves pre-welding multiple layers of tabs together, then welding the tabs to the terminals. Traditionally, the tabs and terminals are centered, with the pre-welding and welding areas symmetrical about their centers. However, to meet specific application requirements, the terminals need to be positioned off-center from the tabs. Simply shifting the pre-welding and welding areas synchronously according to the terminal position can result in an excessively large or small non-welded area on the tab, leading to loosening, stress concentration, and tearing. Therefore, designing a welding structure for off-center terminals is a problem that urgently needs to be solved. Utility Model Content

[0003] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a secondary battery that can improve the reliability of the connection between the eccentric terminal and the tab.

[0004] To achieve the above and other related objectives, this utility model provides a secondary battery, comprising:

[0005] A housing, wherein at least one end of the housing is provided with an opening;

[0006] A cover plate assembly is connected to the housing and closes the opening. The cover plate assembly is provided with a pole post, which is located at one end near the cover plate assembly.

[0007] An electrode assembly includes multiple electrode sheets and multiple tabs extending from at least a first edge of the multiple electrode sheets, the first edge being an edge on the electrode sheet opposite to the opening, the multiple tabs being stacked to form a tab stack.

[0008] The multiple layers of tabs are connected to each other by welding in the first region of the tab stack;

[0009] The pole post is connected to the second region of the pole tab stack by welding.

[0010] The center of the first region is offset by a first preset distance L4 relative to the center of the electrode stack in a first direction;

[0011] The center of the second region is offset by a second preset distance L5 relative to the center of the first region in the first direction;

[0012] The first direction is parallel to the first edge of the electrode sheet.

[0013] In an optional embodiment of this utility model, the center of the second region is aligned with the center of the pole in a second direction, which is perpendicular to the cover plate assembly.

[0014] In an optional embodiment of this utility model, the second region is located within the first region.

[0015] In an optional embodiment of this utility model, the ratio between the first preset distance L4 and the length L1 of the electrode in the first direction is less than 0.5.

[0016] In an optional embodiment of this utility model, the ratio between the length L2 of the first region in the first direction and the length L1 of the tab in the first direction is greater than 0.5.

[0017] In an optional embodiment of this utility model, the ratio of the distance L6 between the first end of the first region and the first end of the electrode tab to the length L1 of the electrode tab in the first direction is less than 0.2; the first end of the first region is the end of the first region away from the center of the electrode tab in the first direction; the first end of the electrode tab is the end of the electrode tab close to the center of the first region in the first direction.

[0018] In an optional embodiment of this utility model, the ratio of the distance L7 between the second end of the first region and the second end of the electrode tab to the length L1 of the electrode tab in the first direction is greater than 0.1 and less than 0.5; the second end of the first region is the end of the first region closer to the center of the electrode tab in the first direction; the second end of the electrode tab is the end of the electrode tab farther from the center of the first region in the first direction.

[0019] In an optional embodiment of this utility model, the ratio of the distance L8 between the second end of the second region and the second end of the first region to the distance L9 between the second end of the second region and the second end of the electrode is greater than 0.3 and less than 0.7; the second end of the second region is the end of the second region closer to the center of the first region in the first direction; the second end of the first region is the end of the first region closer to the center of the electrode in the first direction; the second end of the electrode is the end of the electrode farther from the center of the first region in the first direction.

[0020] In an optional embodiment of this utility model, the ratio between the second preset distance L5 and the length L2 of the first region in the first direction is less than 0.5.

[0021] In an optional embodiment of this utility model, the ratio between the length L3 of the second region in the first direction and the length L2 of the first region in the first direction is greater than 0.5.

[0022] In an optional embodiment of this utility model, a protective sheet made of metal material is provided on the side of the electrode stack away from the electrode post. The protective sheet is connected to the electrode stack by welding and at least covers the first area.

[0023] In an optional embodiment of this utility model, the electrode assembly is formed by stacking multiple layers of separate electrode sheets.

[0024] In an optional embodiment of the present invention, the electrode assembly is formed by winding continuous electrode sheets.

[0025] In an optional embodiment of this utility model, the housing is provided with two opposing openings, and two cover plate assemblies are provided, with the two cover plate assemblies respectively connected to the two openings; the electrode tabs are respectively led out from both ends of the electrode assembly and connected to the electrode posts on the two cover plate assemblies respectively.

[0026] The technical effect of this utility model is as follows: This utility model is designed for secondary batteries with eccentric terminals. The pre-welding area and welding area of ​​the electrode tab are redesigned so that the welding area is offset relative to the electrode tab and also offset relative to the pre-welding area. This allows the welding area to adapt to the offset of the electrode and ensures that the pre-welding area has a suitable size, avoiding defects such as tearing, loosening, and short circuit of the electrode tab. Attached Figure Description

[0027] Figure 1 This is a front view of the secondary battery provided in an embodiment of this utility model;

[0028] Figure 2 yes Figure 1 AA section view;

[0029] Figure 3 yes Figure 2 A magnified view of part of I;

[0030] Figure 4 This is a perspective view of the secondary battery provided in an embodiment of the present invention;

[0031] Figure 5 yes Figure 4 Partial enlarged view of section II;

[0032] Figure 6 This is a perspective view of the electrode assembly provided in an embodiment of the present invention;

[0033] Figure 7This is a front view of the electrode assembly provided in an embodiment of the present invention;

[0034] Figure 8 yes Figure 7 A magnified view of section III;

[0035] It should be noted that, in order to more clearly show the internal structure of the secondary battery, the casing of the secondary battery has been omitted from the above-described drawings of this utility model. Detailed Implementation

[0036] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0037] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0038] A secondary battery, also known as a rechargeable battery or accumulator, is a type of battery that stores energy through charging and releases it when needed. The secondary battery described in this invention specifically refers to a battery with bundled tabs, such as a prismatic lithium-ion battery. These batteries typically have multiple layers of tabs pre-welded into a single unit before being welded to the terminals. Pre-welding ensures uniform contact surfaces between layers, guarantees consistent welding quality and strength, and improves the reliability of the final connection between the tabs and terminals. Pre-welding also prevents delamination of the multi-layered tabs during subsequent processing or use, ensuring the continuity and stability of current transmission. The distribution of the pre-welded area on the tab is crucial to its electrical performance. An excessively large pre-welded area can lead to stress concentration during bending, causing tearing. An excessively small pre-welded area can result in insufficient restraint on excessively long tabs, leading to loosening, folding, or even inverted insertion into the cell, causing a short circuit. Traditional batteries typically have their tabs and terminals aligned at the center, and the pre-welding area is relatively simple, requiring only symmetry between the pre-welding and welding areas of the tab and terminal about their centers. However, to meet certain application requirements, the terminal needs to be positioned off-center from the tab. Simply shifting the pre-welding and welding areas synchronously with the terminal position can result in the non-welded area of ​​the tab being too large or too small, leading to problems such as loosening, stress concentration, and tearing. Therefore, this invention addresses this issue in secondary batteries with off-center terminals by redesigning the pre-welding and welding areas of the tab. The welding area is offset relative to both the tab and the pre-welding area, allowing the welding area to adapt to the terminal offset while ensuring the pre-welding area remains at a suitable size, thus preventing defects such as tearing, loosening, and short circuits in the tab.

[0039] The technical solution of this utility model will be described in detail below with reference to specific embodiments:

[0040] Please see Figure 1-8As shown, the secondary battery provided in the embodiment of this utility model includes a casing, a cover plate assembly 20, and an electrode assembly 10; at least one end of the casing has an opening; the cover plate assembly 20 is connected to the casing and closes the opening, and the cover plate assembly 20 has an electrode post 21, which is disposed near one end of the cover plate assembly 20; the electrode assembly 10 includes multiple electrode sheets and multiple electrode tabs extending from at least a first edge 101 of the multiple electrode sheets, the first edge 101 being the edge on the electrode sheet opposite to the opening, and the multiple electrode tabs are stacked to form an electrode tab stack body 11; the multiple electrode tabs are stacked in the electrode tab stack body The first regions 111 of the electrode stack 11 are connected to each other by welding, for example, by ultrasonic welding in a specific embodiment; the electrode post 21 and the second region 112 of the electrode stack 11 are connected by welding, for example, by laser welding in a specific embodiment; the center of the first region 111 is offset by a first preset distance L4 relative to the center of the electrode stack 11 in a first direction; the center of the second region 112 is offset by a second preset distance L5 relative to the center of the first region 111 in the first direction; the first direction is parallel to the first edge 101 of the electrode sheet.

[0041] The secondary battery provided by this utility model has a certain offset of the terminal post 21 relative to the tab in the first direction to meet the battery specification requirements of special scenarios. Since the terminal post 21 is offset relative to the tab, the welding area (i.e., the second area 112) between the terminal post 21 and the tab will also be offset relative to the tab. If the pre-welding area (i.e., the first area 111) is made symmetrical with the welding area according to the traditional method, a large non-welding area will be generated at the end of the tab that is far from the welding area. This will lead to the tab at this end being prone to loosening, bending, short circuit and other risks. Therefore, this utility model also sets a certain offset between the welding area and the pre-welding area, so that the offset of the pre-welding area relative to the tab is less than the offset of the welding area relative to the tab. This ensures that the end of the tab that is far from the welding area can also be covered by a sufficient pre-welding area, avoiding loosening, bending, short circuit and other phenomena at this end.

[0042] Please see Figure 1 , 3As shown, in an optional embodiment of this invention, the center of the second region 112 is aligned with the center of the electrode post 21 in a second direction, which is perpendicular to the cover plate assembly 20. Alignment of the centers of the electrode post 21 and the second region 112 makes the connection between the electrode post 21 and the tab more uniform and stable, reducing stress concentration and structural deformation caused by misalignment. Furthermore, alignment of the centers of the electrode post 21 and the second region 112 ensures a more reliable electrical connection between the electrode post 21 and the tab, reduces contact resistance, improves the battery's conductivity, and ensures efficient battery operation.

[0043] Please see Figure 6-8 As shown, in an optional embodiment of this utility model, the second region 112 is located within the first region 111. By setting the second region 112 within the first region 111, the space of the tab stack 11 can be fully utilized, improving the utilization efficiency of the battery's internal space and making the battery design more compact. Setting the second region 112 within the first region 111 can also enhance the overall stability of the tab stack 11, reduce stress concentration, and lower the risk of breakage. The pre-welding within the first region 111 provides the tabs with a certain connection strength and stability, making the welding of the second region 112 more reliable. This pre-strengthened design can improve welding quality, reduce the risk of poor welding and joint breakage, and ensure the reliability of electrical connections. The stable structure formed by pre-welding can evenly distribute the heat generated during welding, reducing the risk of thermal deformation and material performance degradation.

[0044] It should be understood that, in addition to reducing the offset of the first region 111, the relative positions of the first region 111, the second region 112 and the electrode stack 11, as well as the dimensional parameters of the first region 111 and the second region 112, are also important factors affecting the electrode performance. The above-mentioned dimensional parameters can be restricted from a variety of different dimensions. The following describes the dimensional parameters of the first region 111, the second region 112 and the electrode from different dimensions in conjunction with several embodiments.

[0045] Example 1

[0046] Please see Figure 8As shown, in an optional embodiment of this utility model, the ratio between the first preset distance L4 and the length L1 of the electrode in the first direction is less than 0.5. In a further specific embodiment, this ratio may be less than 0.2, for example. It should be understood that the offset of the second region 112 relative to the electrode is generally less than 0.5 times the length L1 of the electrode in the first direction. Therefore, in order to make the offset of the first region 111 less than the offset of the second region 112, the ratio between the first preset distance L4 and the length L1 of the electrode in the first direction should also be less than 0.5. In a further embodiment, limiting this ratio to below 0.2 can ensure that the end of the electrode away from the welding area can also have sufficient pre-welded area coverage, avoiding loosening, folding, short circuit, and other phenomena of the electrode at this end.

[0047] Example 2

[0048] Please see Figure 8 As shown, in an optional embodiment of this utility model, the ratio between the length L2 of the first region 111 in the first direction and the length L1 of the tab in the first direction is greater than 0.5. In a further specific embodiment, this ratio can be greater than 0.6 and less than 0.8. It should be understood that this ratio reflects the proportion of the pre-soldered area on the tab stack 11. If the ratio is too large, the bent tab will easily experience stress concentration, causing tearing during the bending process. If the ratio is too small, the excessively long tab will not have sufficient restraint, leading to loosening, folding, or even inverted insertion into the battery cell, resulting in a short circuit. This embodiment further limits the ratio to between 0.6 and 0.8, which can ensure that the tab does not loosen while avoiding tearing of the tab due to stress concentration.

[0049] Example 3

[0050] Please see Figure 8 As shown, in an optional embodiment of this utility model, the ratio of the distance L6 between the first end of the first region 111 and the first end of the electrode tab to the length L1 of the electrode tab in the first direction is less than 0.2; the first end of the first region 111 is the end of the first region 111 away from the center of the electrode tab in the first direction; the first end of the electrode tab is the end of the electrode tab close to the center of the first region 111 in the first direction. This relatively small ratio facilitates the welding and guiding structure of ultrasonic waves from the bottom of the electrode post 21.

[0051] Example 4

[0052] Please see Figure 8As shown, in an optional embodiment of the present invention, the ratio of the distance L7 between the second end of the first region 111 and the second end of the electrode tab to the length L1 of the electrode tab in the first direction is greater than 0.1 and less than 0.5; the second end of the first region 111 is the end of the first region 111 closer to the center of the electrode tab in the first direction; the second end of the electrode tab is the end of the electrode tab farther from the center of the first region 111 in the first direction. In this embodiment, the ratio between the distance L7 between the second end of the first region 111 and the second end of the tab and the length L1 of the tab in the first direction reflects the proportion of the pre-welded area at the end of the tab away from the welding area. If the ratio is too small, the tab is prone to stress concentration during bending due to the lack of fixation by laser welding, causing tearing during the bending process. If the ratio is too large, the end of the tab away from the welding area is not fixed due to the lack of fixation, and the shape of the tab is not fixed. Multi-layered tabs are prone to folding, short circuits of inverted cells, and scattered cell shapes. In this embodiment, the ratio is set between 0.1 and 0.5, which can ensure that the tab does not loosen while avoiding tearing of the tab due to stress concentration.

[0053] Example 5

[0054] Please see Figure 8 As shown, in an optional embodiment of this utility model, the ratio of the distance L8 between the second end of the second region 112 and the second end of the first region 111 to the distance L9 between the second end of the second region 112 and the second end of the electrode tab is greater than 0.3 and less than 0.7; the second end of the second region 112 is the end of the second region 112 closer to the center of the first region 111 in the first direction; the second end of the first region 111 is the end of the first region 111 closer to the center of the electrode tab in the first direction; the second end of the electrode tab is the end of the electrode tab farther from the center of the first region 111 in the first direction. In this embodiment, the ratio of the distance L8 between the second end of the second region 112 and the second end of the first region 111 to the distance L9 between the second end of the second region 112 and the second end of the electrode tab also reflects the proportion of the pre-welded area at the end of the electrode tab far from the welding area. This ratio is set between 0.3 and 0.7, which can ensure that the electrode tab does not loosen while avoiding electrode tab tearing caused by stress concentration.

[0055] Example 6

[0056] Please see Figure 8As shown, in an optional embodiment of this utility model, the ratio between the second preset distance L5 and the length L2 of the first region 111 in the first direction is less than 0.5. In a further embodiment, this ratio can be set below 0.3, for example. This ratio reflects the offset of the welding area relative to the pre-welding area. If the offset is too large, it will cause the pre-welding area to over-cover the tab, resulting in stress concentration and tearing of the tab. In this embodiment, the ratio is set below 0.3, which can ensure that the tab does not loosen while avoiding tab tearing caused by stress concentration.

[0057] Example 7

[0058] Please see Figure 8 As shown, in an optional embodiment of this utility model, the ratio between the length L3 of the second region 112 in the first direction and the length L2 of the first region 111 in the first direction is greater than 0.5. In a further specific embodiment, this ratio can be set, for example, between 0.6 and 0.8. It should be understood that the length L3 of the welding area is limited by the size of the electrode post 21, so L3 should be definite. Therefore, when the ratio is too small, it means that the pre-welding area is too large; when the ratio is too large, it means that the pre-welding area is too small. In this embodiment, the ratio is set between 0.6 and 0.8, which enables the pre-welding area to have a better size, ensuring that the electrode tab does not loosen while avoiding electrode tab tearing caused by stress concentration.

[0059] Please see Figure 3 As shown, in an optional embodiment of this utility model, a protective sheet 12 made of metal material is provided on the side of the tab stack 11 away from the pole post 21. The protective sheet 12 is connected to the tab stack 11 by welding, and the protective sheet 12 at least covers the first region 111. The protective sheet 12 can provide auxiliary support and protection for the tab stack 11, and improve the connection strength between the tab stack 11 and the pole post 21.

[0060] The secondary battery provided by this utility model does not have any particular limitations on the specific configuration of the electrode assembly 10. For example, in some embodiments, the electrode assembly 10 can be formed by stacking multiple layers of separate electrode sheets. In other embodiments, the electrode assembly 10 can also be formed by winding continuous electrode sheets.

[0061] The secondary battery provided by this utility model does not have any special restrictions on the way the terminals 21 are led out. For example, in some embodiments, the housing has two opposing openings, and there are two cover plate assemblies 20, which are respectively connected to the two openings; the tabs are led out from both ends of the electrode assembly 10 and connected to the terminals 21 on the two cover plate assemblies 20 respectively. In other embodiments, the secondary battery may also have only one cover plate assembly 20, and the two terminals 21 may be located at both ends of the cover plate assembly 20, or one terminal 21 may be located on the cover plate assembly 20 and the other terminal 21 may be located on the bottom surface of the housing.

[0062] In summary, the secondary battery provided by this utility model has a certain offset relative to the tab in the first direction to meet the battery specification requirements of special scenarios. Since the pole is offset relative to the tab, the welding area between the pole and the tab will also be offset relative to the tab. This utility model also sets a certain offset between the welding area and the pre-welding area, so that the offset of the pre-welding area relative to the tab is less than the offset of the welding area relative to the tab, thereby ensuring that the end of the tab away from the welding area can also be covered by a sufficient pre-welding area, avoiding loosening, folding, short circuit and other phenomena at this end.

[0063] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

[0064] Throughout this description, numerous specific details, such as examples of components and / or methods, are provided to provide a complete understanding of embodiments of the present invention. However, those skilled in the art will recognize that embodiments of the present invention may be practiced without one or more of these specific details or by other devices, systems, components, methods, parts, materials, components, etc. In other instances, well-known structures, materials, or operations have not been specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention.

Claims

1. A secondary battery, characterized in that, include: A housing, wherein at least one end of the housing is provided with an opening; A cover plate assembly is connected to the housing and closes the opening. The cover plate assembly is provided with a pole post, which is located at one end near the cover plate assembly. An electrode assembly includes multiple electrode sheets and multiple tabs extending from at least a first edge of the multiple electrode sheets, the first edge being an edge on the electrode sheet opposite to the opening, the multiple tabs being stacked to form a tab stack. The multiple layers of tabs are connected to each other by welding in the first region of the tab stack; The pole post is connected to the second region of the pole tab stack by welding. The center of the first region is offset by a first preset distance L4 relative to the center of the electrode stack in a first direction; The center of the second region is offset by a second preset distance L5 relative to the center of the first region in the first direction; The first direction is parallel to the first edge of the electrode sheet.

2. The secondary battery according to claim 1, characterized in that, The center of the second region is aligned with the center of the pole in a second direction, which is perpendicular to the cover plate assembly; the second region is located within the first region.

3. The secondary battery according to claim 1, characterized in that, The ratio between the first preset distance L4 and the length L1 of the electrode in the first direction is less than 0.

5.

4. The secondary battery according to claim 1, characterized in that, The ratio between the length L2 of the first region in the first direction and the length L1 of the tab in the first direction is greater than 0.

5.

5. The secondary battery according to claim 1, characterized in that, The ratio of the distance L6 between the first end of the first region and the first end of the electrode tab to the length L1 of the electrode tab in the first direction is less than 0.2; the first end of the first region is the end of the first region away from the center of the electrode tab in the first direction; the first end of the electrode tab is the end of the electrode tab close to the center of the first region in the first direction.

6. The secondary battery according to claim 1, characterized in that, The ratio of the distance L7 between the second end of the first region and the second end of the electrode to the length L1 of the electrode in the first direction is greater than 0.1 and less than 0.5; the second end of the first region is the end of the first region closer to the center of the electrode in the first direction; the second end of the electrode is the end of the electrode farther from the center of the first region in the first direction.

7. The secondary battery according to claim 1, characterized in that, The ratio between the second preset distance L5 and the length L2 of the first region in the first direction is less than 0.

5.

8. The secondary battery according to claim 1, characterized in that, The tab stack is provided with a protective sheet made of metal material on the side away from the pole post. The protective sheet is connected to the tab stack by welding and at least covers the first area.

9. The secondary battery according to claim 1, characterized in that, The electrode assembly is formed by stacking multiple layers of separate electrode sheets, or the electrode assembly is formed by winding continuous electrode sheets.

10. The secondary battery according to claim 1, characterized in that, The housing has two opposing openings, and there are two cover plate assemblies, which are respectively connected to the two openings; the electrode tabs are respectively led out from both ends of the electrode assembly and connected to the electrode posts on the two cover plate assemblies.

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