Battery cell assembly

Abstract

The battery cell assembly comprises a positive pole piece, a negative pole piece and a busbar, a diaphragm is arranged between the positive pole piece and the negative pole piece, a battery cell body is formed through winding, a first mounting area and a second mounting area which are spaced from each other are formed at the end of the battery cell body, and the busbar is arranged in the first mounting area. A tab is formed at one end of the negative pole piece and is arranged in the second mounting area at the end part of the battery cell body, and the tab extends towards the first mounting area, covers the top of the busbar and is connected with the busbar, so that the yield of the battery cell assembly can be improved.

Description

Technical Field

[0001] This application relates to the field of batteries, and in particular to a battery cell assembly. Background Technology

[0002] In related technologies, due to the thinness of the tabs and the thickness of the busbars, the busbars typically cover the tabs, and welding is performed from one side of the busbars towards the tabs. During welding, the negative electrode busbar needs to be pressed against the surface of the multi-layered stacked tabs. After pressure bonding, laser penetration welding is performed. Since it is necessary to penetrate the thick busbar from top to bottom and weld the tabs below, the welding laser needs to avoid excessive ablation of the tabs while penetrating the busbar. During this process, the weld pool is very likely to break through the tab structure located below the busbar, forming a through weld mark, which directly burns the cell body or separator connected to the tab. At the same time, the weld slag generated during the process of penetrating the busbar to weld the tabs may fall between the separator or electrode sheets, causing the risk of micro-short circuits, which limits the yield of existing cell modules. Therefore, how to improve the yield of cell modules has become the technical problem to be solved in this application. Utility Model Content

[0003] This application aims to at least address one of the technical problems existing in the prior art. Therefore, one objective of this application is to provide a battery cell assembly that can improve the yield rate of battery cell assemblies.

[0004] A battery cell assembly according to an embodiment of this application includes: a positive electrode and a negative electrode, wherein a separator is disposed between the positive electrode and the negative electrode and the battery cell body is formed by winding, and a first mounting area and a second mounting area are formed at the end of the battery cell body and spaced apart from each other; a busbar is disposed in the first mounting area; wherein one end of the negative electrode has a tab formed and is disposed in the second mounting area at the end of the battery cell body, the tab extends toward the first mounting area and covers the top of the busbar and is connected to the busbar.

[0005] According to an embodiment of this application, a battery cell assembly has a tab extending toward a first mounting area and covering the top of a busbar and connecting thereto. In this structure, the tab covers the top of the busbar and is located above the busbar. When welding is performed, welding is performed from the tab toward the busbar, avoiding the need for welding to penetrate a thick busbar. This reduces the difficulty of high-power lasers penetrating a thick busbar while avoiding excessive ablation of the tab. It also reduces the generation of penetrating weld marks and prevents weld slag or molten metal beads from embedding between the separator or the electrode, thereby improving the yield of the battery cell assembly.

[0006] According to some embodiments of the present application, the battery cell assembly has multiple tabs arranged on one axial side edge of the negative electrode sheet and spaced apart from each other; wherein the length of the multiple tabs gradually increases from the side edge of the negative electrode sheet closer to the center of the battery cell body to the side edge farther away from the center of the battery cell body.

[0007] According to some embodiments of the present application, the battery cell assembly has multiple sets of tabs arranged at intervals along one axial side edge of the negative electrode sheet; wherein the length of the multiple sets of tabs gradually increases from the side edge of the negative electrode sheet closer to the center of the battery cell body to the side edge farther away from the center of the battery cell body.

[0008] According to some embodiments of the present application, each group of tabs includes a plurality of tabs, and the length of the tab closer to the center of symmetry of each group of tabs is greater than the length of the tab farther from the center of symmetry of the tabs in at least two adjacent tabs.

[0009] According to some embodiments of the present application, the battery cell assembly has a plurality of spaced tab arrangement segments on one side edge of the negative electrode sheet, and the length of each tab arrangement segment is l1, l2, ... ln in sequence. The length of one side edge of the negative electrode sheet is L, and satisfies: 1 / 2L≤l1+l2+...+ln.

[0010] According to some embodiments of the present application, in the battery cell assembly, adjacent sets of tabs are spaced apart with intervals of l1, l2, ... ln.

[0011] According to some embodiments of the present application, a battery cell assembly has multiple electrodes arranged in one electrode arrangement segment, and the length of the electrode located at the symmetrical center of the electrode arrangement segment is greater than the length of any other electrode.

[0012] According to some embodiments of the present application, in the battery cell assembly, the length of the electrode located at its own center of symmetry in each group of electrodes is dx, the dx of the edge closer to the center of the battery cell body in two adjacent groups of electrodes is d1, the dx of the edge farther from the center of the battery cell body in two adjacent groups of electrodes is d2, and satisfies: d2≤d1.

[0013] According to some embodiments of the present application, the battery cell assembly is characterized in that both the first mounting area and the second mounting area are configured in a fan shape.

[0014] According to some embodiments of the present application, in the cell assembly, the thickness of the busbar is greater than the thickness of any one of the tabs.

[0015] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0016] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0017] Figure 1 This is a schematic diagram of the structure of a battery cell assembly according to an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of the unwound portion of the negative electrode sheet of the battery cell assembly according to an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the structure of the negative electrode sheet of the battery cell assembly after winding, without bending and flattening the tab;

[0020] Figure 4 yes Figure 3 A top-view structural diagram.

[0021] Figure label:

[0022] 100. Battery cell assembly;

[0023] 1. Negative electrode plate; 11. Electrode tab;

[0024] 2. Battery cell body; 21. First mounting area; 22. Second mounting area;

[0025] 3. Busbar;

[0026] 4. Battery cell casing;

[0027] 5. Positive electrode;

[0028] 6. Positive busbar. Detailed Implementation

[0029] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0030] The following is for reference. Figures 1-4 The battery cell assembly 100 according to an embodiment of this application is described.

[0031] According to the present application, the battery cell assembly 100 includes a positive electrode, a negative electrode 1, and a busbar 3. A diaphragm is disposed between the positive electrode and the negative electrode 1, and the battery cell body 2 is formed by winding. The battery cell body 2 has a first mounting area 21 and a second mounting area 22 spaced apart from each other at its end. The busbar 3 is disposed in the first mounting area 21. One end of the negative electrode 1 has a tab 11 and is disposed in the second mounting area 22 at the end of the battery cell body 2. The tab 11 extends toward the first mounting area 21, covers the top of the busbar 3, and is connected to the busbar 3.

[0032] In related technologies, due to the thinness of the tab 11 and the thickness of the busbar 3, the busbar 3 typically covers the tab 11, and welding is performed from one side of the busbar 3 towards the tab 11. During welding, the negative electrode busbar needs to be pressed against the surface of the multi-layered stacked tab 11. After pressure bonding, laser penetration welding is performed. Because it is necessary to penetrate the thicker busbar from top to bottom and fuse the lower tab 11, the difference in thickness between the two requires the high-power laser to avoid excessive ablation of the tab 11 while penetrating the busbar. However, the tab 11 is multi-layered and the shaping precision is not high. Insufficient welding technology can lead to gaps or wrinkles between layers, resulting in a significant reduction in the actual contact area of ​​the welding interface. This non-ideal contact condition causes laser energy to concentrate abnormally in local areas, making it easy for the molten pool to break through the lower tab 11 structure and form a through weld mark. This can directly burn the adjacent bare cell body 2 or the separator. More seriously, energy reflection and metal vapor splashing at the gaps can generate weld slag or molten metal beads, which may embed between the separator or the electrode, causing micro-short circuit hazards. In order to ensure the yield of the existing cell assembly 100, the welding process has high requirements.

[0033] A tab 11 is disposed in the first mounting area 21 at the end of the cell body 2, and a busbar 3 is disposed in the second mounting area 22 at the end of the cell body 2. The tab 11 extends and covers the top of the busbar 3, changing the welding direction to welding the tab 11 to the busbar 3. The tab 11 serves as the initial layer for laser action. The thinner tab 11 allows for faster formation of the weld pool. Subsequent energy diffuses naturally downwards to the busbar 3 through heat conduction. This process creates a temperature gradient from the surface to the interior, avoiding the need to weld through the busbar 3 before welding the tab 11 to the busbar 3, which is necessary in existing technologies where the busbar 3 is thick, thus preventing damage to the busbar 3. Absorbing excessive energy can lead to uncontrolled welding pool issues, fundamentally avoiding the risk of melting through the tab 11 and damaging the cell body 2. Simultaneously, with the tab 11 covering the busbar 3, the welding position is located in a relatively enclosed area of ​​the cell assembly 100, and the tab 11 covering the busbar 3 forms a certain obstruction. Weld slag generated during welding is difficult to fall directly between the separator or electrode due to the obstruction of the tab 11 and busbar 3. When a small amount of weld slag is generated, it is confined to the welding area between the tab 11 and busbar 3, making it less likely to cause micro-short circuits, further improving the safety and stability of the cell assembly 100. Through the above structural design, the two main risks of through-weld burns to the cell body 2 or separator, and weld slag causing micro-short circuits, are effectively avoided. This reduces the failure of the cell assembly 100 due to poor welding, resulting in a lower number of defective products during the production of the cell assembly 100. With production processes, raw materials, and other conditions remaining unchanged, a significant improvement in the yield rate of battery cell modules was ultimately achieved, reaching 100%.

[0034] In some embodiments of this application, a cell housing 4 is also included, and a receiving cavity is formed inside the cell housing 4, and the cell body 2 is adapted to be inside the receiving cavity.

[0035] According to some embodiments of the present application, the battery cell assembly 100 has multiple tabs 11 arranged on one side of the negative electrode plate 1 and spaced apart from each other; wherein the length of the multiple tabs 11 gradually increases from the side edge of the negative electrode plate 1 that is close to the center of the battery cell body 2 to the side edge that is far away from the center of the battery cell body 2.

[0036] It should be noted that after the positive and negative electrode sheets 1 are wound, the tab 11 of the negative electrode sheet 1 needs to be bent and flattened, and the tab 11 is attached to the busbar 3 of the first mounting area 21. After the positive and negative electrode sheets 1 are wound, a cylindrical battery cell body 2 is formed. It can be understood that the tab 11 closer to the edge of the battery cell will have a greater displacement and stretching after being deformed by pressure. It needs to be set to a longer length to allow enough length to compensate for the deformation caused by pressure, so that the tab 11 at the edge can still cover the busbar 3 of the first mounting area 21, maintaining the contact area and connection stability with the busbar 3. The tab 11 closer to the center has a relatively smaller degree of deformation under pressure. The shorter length is sufficient to meet the connection requirements with the busbar 3. The gradual change in length ensures that the tabs 11 can accurately and stably cover the busbar 3 under pressure at different positions, achieving a reliable electrical connection. At the same time, the tabs 11 are constructed as multiple tabs and are arranged at intervals on one side of the axial edge of the negative electrode plate 1. This means that when the negative electrode plate 1 is unfolded, the tabs 11 are arranged at intervals. When the negative electrode plate 1, positive electrode plate, and separator are wound together to form the battery cell body 2, these spaced tabs 11 will be distributed along the circumference of the battery cell to the second mounting area 22, laying the structural foundation for the subsequent bending and flattening of the tabs 11 of the negative electrode plate 1 and their connection to the busbar 3 in the first mounting area 21.

[0037] According to some embodiments of the present application, the battery cell assembly 100 has multiple sets of tabs 11 arranged on one side of the negative electrode plate 1 and spaced apart from each other; wherein the length of the multiple sets of tabs 11 gradually increases from the side edge of the negative electrode plate 1 that is close to the center of the battery cell body 2 to the side edge that is far away from the center of the battery cell body 2.

[0038] It should be noted that in some embodiments of this application, the tabs 11 are constructed in multiple groups. Compared with multiple tabs 11, multiple groups of tabs 11 means that the tabs 11 are arranged in groups, making the distribution of the tabs 11 more regular and modular. The tabs 11 in each group are arranged closely in space and close to each other to form a sub-unit. Multiple tabs 11 can be divided into a group, and there is a clear interval between groups. The uniform and regular distribution makes the current transmission path more symmetrical, which can effectively avoid the problem of excessive local current density caused by uneven distribution of tabs 11. The uniformly distributed groups of tabs 11 can distribute the current more evenly, reduce the local overheating phenomenon caused by uneven current distribution, and improve the stability and safety of the cell assembly 100.

[0039] According to some embodiments of the present application, the battery cell assembly 100 includes a plurality of tabs 11 in each group of tabs 11, and the length of the tab 11 closer to the center of symmetry of each group of tabs 11 is greater than the length of the tab 11 farther from the center of symmetry of the tab 11 in at least two adjacent tabs 11.

[0040] During the cell winding process, as the negative electrode 1 is wound layer by layer with the positive electrode and the separator, the position near the symmetrical center of each set of tabs 11 will gradually be wrapped by the outer electrode, making this position farther and farther away from the busbar 3 of the first mounting area 21. The position far away from the symmetrical center of each set of tabs 11 is relatively closer to the busbar 3 because it is on the outside of the winding structure. If the length of each set of tabs 11 is the same, the tabs 11 near the symmetrical center will have difficulty touching the busbar 3 after winding, resulting in connection failure and affecting the normal operation of the cell. The tabs 11 at the symmetrical center of each set of tabs 11 are longer, which can effectively make up for the difference in spatial distance. The longer center tabs 11 can extend smoothly to the first mounting area 21 where the busbar 3 is located after winding, thanks to their own length advantage, ensuring a tight fit with the busbar 3. The relatively shorter edge tabs 11 are originally located on the outside of the busbar 3, so they do not need to be too long to achieve a reliable connection.

[0041] According to some embodiments of the present application, the battery cell assembly 100 has a plurality of spaced tabs 11 arranged on one side edge of the negative electrode plate 1. The lengths of each tab 11 arranged segment are l1, l2, ..., ln, and the length of one side edge of the negative electrode plate 1 is L, and satisfies: 1 / 2L≤l1+l2+...+ln.

[0042] It is understandable that, given 1 / 2L ≤ l1 + l2 + ... + ln, the total length of the tab 11 arrangement segment must be at least half the length of one edge of the negative electrode plate 1. Since the battery cell is cylindrical after winding, ensuring that the total length of the tab 11 arrangement segment is at least half the length of one edge of the negative electrode plate 1 allows the tab 11 to cover the area where the busbar 3 is located more extensively along the circumference of the battery cell after winding. Even if the position of the tab 11 shifts slightly due to process errors or battery cell deformation during winding, the longer tab 11 arrangement segment can still ensure effective overlap with the busbar 3 and maintain a stable electrical connection. From the perspective of connection stability, a longer tab 11 arrangement segment means a larger contact area. In the welding process, a larger contact area provides more tolerance for welding operations and reduces the risk of connection failure due to welding position deviations.

[0043] According to some embodiments of the present application, in the battery cell assembly 100, two adjacent sets of tabs 11 are spaced apart with intervals of l1, l2, ... ln.

[0044] When the negative electrode plate 1 is unfolded, the tabs 11 are arranged alternately with the spacing. Since the length of the tab 11 arrangement segment and the corresponding spacing distance are equal, the total length of the tab 11 arrangement segment is also equal to the total length of the spacing. Therefore, the total length of the tab 11 arrangement segment must occupy half of the total length of one edge of the negative electrode plate 1. During the winding process of the battery cell into the battery cell body 2, this length ratio in the unfolded state ensures the reasonable distribution of the tab 11 arrangement segments in the circumferential direction after winding. The tab 11 arrangement segment occupying half the length allows it to evenly and fully cover the area connected to the busbar 3. When the battery cell is wound and the busbar 3 in the first mounting area 21 needs to establish a connection with the tabs 11, the fact that the tab 11 arrangement segment accounts for half ensures that enough tabs 11 can contact the busbar 3, forming... Stable electrical connection points; from the perspective of current transmission, a sufficient proportion of tab 11 length means a larger contact area, which can reduce contact resistance and ensure efficient current transmission; from the perspective of structural stability, a uniformly distributed and reasonably proportioned tab 11 arrangement can better disperse stress when the cell is subjected to external force or vibration, avoiding excessive local stress that could lead to failure of the tab 11 connection with the electrode sheet; from the perspective of production process, a clear length proportion and spacing pattern facilitates precise positioning and operation of welding equipment, improves welding quality and production efficiency, and ultimately improves the overall yield and performance of the cell assembly 100.

[0045] According to some embodiments of the present application, a battery cell assembly 100 has multiple tabs 11 arranged in a tab arrangement section, and the length of the tab 11 located at the symmetrical center of the tab arrangement section is greater than the length of any other tab 11.

[0046] During the cell winding process, the negative electrode 1, positive electrode, and separator intertwine to form the cell body 2. After winding, the tabs 11 arrangement section changes from a linear arrangement at the edge of the negative electrode 1 to a ring distribution around the circumference of the cell. Since the winding is a layer-by-layer wrapping from the outside in, the tabs 11 located at the symmetrical center of the tab 11 arrangement section will be wrapped by the outer electrode layers and tabs 11 after winding, thus placing them closer to the center of the cell. The busbar 3 of the first mounting area 21 is usually located in the outer region of the cell end. Therefore, the tabs 11 located at the symmetrical center of the tab 11 arrangement section are positioned closer to the center of the cell than the tabs 11 arranged in the same way. The tabs 11 in other locations within the section are furthest from the busbar 3 of the first installation area 21. If all tabs 11 in the section are of the same length, the tab 11 located at the center of symmetry will be the furthest from the busbar 3, resulting in insufficient length when connecting to the busbar 3, which will lead to ineffective overlap and affect current transmission. Therefore, the tab 11 located at the center of symmetry in the section is designed to be longer, allowing it to extend to the busbar 3 after winding and establish a stable connection with it. This design ensures that each tab 11 in the section can accurately connect to the busbar 3, avoiding problems such as increased resistance and poor current transmission caused by poor connection, thereby improving the electrical performance of the cell assembly 100.

[0047] According to some embodiments of the present application, in the battery cell assembly 100, the length of the electrode 11 located at its own center of symmetry in each group of electrodes 11 is dx, the dx of the side edge of two adjacent groups of electrodes 11 that is closer to the center of the battery cell body 2 is d1, the dx of the side edge of two adjacent groups of electrodes 11 that is farther away from the center of the battery cell body 2 is d2, and satisfies: d2≤d1.

[0048] It is understandable that d2≤d1 means that in each group of tabs 11 further away from the center of the cell body 2, the length of the tab 11 located at its own center of symmetry is greater than or equal to the length of the tab 11 closer to the center. Because during the winding process of the cell, the negative electrode 1, positive electrode, and separator are intertwined to form a column-like structure, the busbar 3 of the first mounting area 21 is usually fixed in the outer region of the cell end. Adjacent groups of tabs 11 are distributed along the circumference of the cell after winding. The group of tabs 11 further away from the center of the cell body 2, because its electrode layer is on the outer layer, is spatially different from the group of tabs 11 located at the center. The busbar 3 on the outer side of the end is farther away; conversely, the tabs 11 group closer to the center of the cell body 2 are relatively closer to the busbar 3 because they are in the inner layer of the electrode sheet. This makes it more difficult for the tabs 11 group at different positions to establish a connection with the busbar 3. By setting the tabs 11 group farther away from the center of the cell body 2, the length of the tab 11 located at its own center of symmetry is greater than or equal to the length of the tab 11 closer to the center. The longer tabs 11 can extend smoothly to the busbar 3 after being wound, ensuring a tight fit with the busbar 3 and improving the connection strength with the busbar 3.

[0049] According to some embodiments of the present application, the battery cell assembly 100 is characterized in that the first mounting area 21 and the second mounting area 22 are both configured in a fan shape.

[0050] The first mounting area 21 and the second mounting area 22 are fan-shaped. Within the fan-shaped area, when the tab 11 extends from the second mounting area 22 to the first mounting area 21 and connects to the busbar 3, the extension path of the tab 11 is smoother due to the angle characteristics of the fan shape, reducing the possibility of bending and twisting. The smooth connection path helps to reduce the contact resistance between the tab 11 and the busbar 3, making the current transmission more efficient. At the same time, the fan-shaped mounting area provides a relatively concentrated and regular connection space, which facilitates the precise operation of welding equipment, improves the accuracy and reliability of welding, and reduces problems such as cold solder joints and missing solder joints, thereby improving the yield and electrical performance of the battery cell assembly 100.

[0051] According to some embodiments of the present application, the thickness of the busbar 3 in the battery cell assembly 100 is greater than the thickness of any one of the tabs 11.

[0052] In the battery cell assembly 100, the busbar 3 not only conducts current but also provides structural support, especially when the battery cell is subjected to external pressure and vibration. In contrast, the tab 11 prioritizes the flexibility and conductivity of its connection with the electrode. The thicker busbar 3 has higher structural strength and rigidity, better resisting external mechanical stress. During the operation of new energy vehicles, the battery cell is frequently subjected to bumps and vibrations. The thicker busbar 3 can maintain its shape stability, preventing the connection with the tab 11 from loosening or breaking due to deformation. The tab 11, on the other hand, maintains a relatively thin thickness, which meets the flexibility requirements for connection with the electrode without compromising the winding process and overall structural compactness of the battery cell due to excessive thickness. This difference in thickness achieves a balance between function and structure.

[0053] Meanwhile, in this structure, the thinner tab 11 is on top and the thicker busbar 3 is on the bottom, which reduces the difficulty of welding the tab 11 to the busbar 3, avoids the situation in the prior art that requires welding through the busbar 3, and also reduces the generation of through weld marks, preventing weld slag or molten metal beads from embedding between the separator or electrode, which can improve the yield of the cell assembly 100.

[0054] In some embodiments of this application, a positive electrode tab 5 and a positive electrode bus 6 are also included. A positive electrode tab 5 is formed at one end of the positive electrode sheet and disposed at the other end of the cell body 2. The positive electrode bus 6 is welded to the positive electrode tab 5.

[0055] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and 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 of this application.

[0056] In the description of this application, "first feature" and "second feature" may include one or more of the features.

[0057] In the description of this application, "multiple" means two or more.

[0058] In the description of this application, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0059] In the description of this application, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An electrochemical cell assembly, comprising: include: A positive electrode and a negative electrode (1) are provided between the positive electrode and the negative electrode (1) and a cell body (2) is formed by winding. The end of the cell body (2) is formed with a first mounting area (21) and a second mounting area (22) spaced apart from each other. Busbar (3), wherein the busbar (3) is disposed in the first installation area (21); wherein One end of the negative electrode plate (1) is formed with a tab (11) and is disposed in the second mounting area (22) at the end of the cell body (2). The tab (11) extends toward the first mounting area (21) and covers the top of the busbar (3) and is connected to the busbar (3).

2. The cell assembly of claim 1, wherein, The tabs (11) are configured as multiple and are spaced apart from each other on one side of the axial edge of the negative electrode plate (1); wherein The length of the plurality of tabs (11) gradually increases from the edge of the negative electrode plate (1) closer to the center of the cell body (2) to the edge away from the center of the cell body (2).

3. The cell assembly of claim 1, wherein, The tabs (11) are constructed in multiple groups and are arranged at intervals along one side of the axial direction of the negative electrode plate (1); wherein The length of the multiple sets of tabs (11) gradually increases from the edge of the negative electrode plate (1) closer to the center of the cell body (2) to the edge away from the center of the cell body (2).

4. The cell assembly of claim 3, wherein, Each set of electrodes (11) includes a plurality of electrodes (11), and the length of the electrode (11) closer to the center of symmetry of each set of electrodes (11) is greater than the length of the electrode (11) farther from the center of symmetry of the electrode (11).

5. The cell assembly of claim 4, wherein, The negative electrode plate (1) has a plurality of spaced tabs (11) arranged on one side edge. The length of each tab (11) arranged segment is l1, l2, ... ln, and the length of one side edge of the negative electrode plate (1) is L, and satisfies: 1 / 2L≤l1+l2+...+ln.

6. The cell assembly of claim 4, wherein, The adjacent two sets of electrodes (11) are spaced apart with intervals of l1, l2, ... ln.

7. The cell assembly of claim 5, wherein, Within one of the electrode (11) arrangement sections, a plurality of electrode (11) are provided, and the length of the electrode (11) located at the symmetrical center of the electrode (11) arrangement section is greater than the length of any other electrode (11).

8. The cell assembly of claim 5, wherein, In each group of electrodes (11), the length of the electrode (11) located at its own center of symmetry is dx. In two adjacent groups of electrodes (11), the edge of the side closer to the center of the cell body (2) is dx = d1, and the edge of the side of the side farther from the center of the cell body (2) is dx = d2, and d2 ≤ d1 is satisfied.

9. The cell assembly of any of claims 1-8, wherein, Both the first mounting area (21) and the second mounting area (22) are constructed in a fan shape.

10. The cell assembly of claim 9, wherein, The thickness of the busbar (3) is greater than the thickness of any one of the tabs (11).

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