An electric cell, a welding method of an electric cell, and a battery

Abstract

The present application relates to a kind of battery, the welding method of electric core and electric core, the electric core includes: at least one bare electric core, each bare electric core extends and has tab, tab includes at least two layers of tab layer;Adapter piece, each tab is welded on the adapter piece, wherein, in the direction of the end of tab from the root of bare electric core, the tab layer of outer layer successively forms hold-down portion and welding portion in two adjacent tab layers, the hold-down portion covers and holds on the tab layer of inner layer, the welding portion is welded on the adapter piece;The welding method of the electric core is used to weld the bare electric core with adapter piece or outer structure, and the tab of different layers is welded on the adapter piece in sequence in the present application, hold-down portion is formed between the tab layer of multiple layers, and welding portion is formed between the tab layer of multiple layers and adapter piece, so as to solve the problem of virtual welding of tab and adapter piece welding.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, and in particular to a battery cell, a battery cell welding method, and a battery. Background Technology

[0002] Energy is a hot topic of global concern, with energy storage being the most crucial aspect. Currently, rechargeable batteries, particularly lithium-ion batteries as a novel type of rechargeable battery, are a vital component of energy storage. They offer advantages such as high energy and power density, high operating voltage, light weight, small size, long cycle life, good safety, and environmental friendliness, making them promising for applications in portable appliances, power tools, large-scale energy storage, and electric vehicle power supplies.

[0003] Some types of battery cells require adapter plates during manufacturing. These adapter plates connect the leads to the terminals, typically using welding. High-energy-density batteries are currently one of the development directions for lithium-ion batteries. For laminated cells, the more layers, the higher the cell capacity. However, as the number of layers increases, the empty foil areas of the copper and / or aluminum foil also become thicker. During the welding process, factors such as the thickness of the adapter plate, leads, or terminals, welding time, and welding temperature can easily lead to incomplete soldering, resulting in poor contact later on.

[0004] In the prior art, Chinese patent publication number CN115149112A, entitled "Bare Cell, Method for Preparing a Bare Cell and Battery," discloses a bare cell structure including multiple electrode sheets and a separator. The multiple electrode sheets include multiple positive electrode sheets and multiple negative electrode sheets. The multiple positive electrode sheets are divided into multiple groups according to the length of their empty foil areas. The multiple groups of positive electrode sheets are stacked sequentially in order of increasing length of their empty foil areas. The empty foil areas of the multiple groups of positive electrode sheets are then welded together in stages to form positive electrode tabs. And / or, the multiple negative electrode sheets are divided into multiple groups according to the length of their empty foil areas. The multiple groups of negative electrode sheets are stacked sequentially in order of increasing length of their empty foil areas. The empty foil areas of the multiple groups of negative electrode sheets are then welded together in stages to form negative electrode tabs. Existing technologies enable graded welding by setting the empty foil area of ​​the electrode to different lengths, thereby improving the welding effect, avoiding cold solder joints, and increasing the number of electrode stacks to increase the cell capacity. However, existing technologies only set the longest electrode to be welded to the adapter piece, and the other electrodes are only welded in stages. There is still a possibility of cold solder joints between the other electrodes and the adapter piece, which cannot fundamentally solve the problem of cold solder joints. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problem of incomplete welding in the welding of the tabs and adapter plates of the battery cell in the prior art, and to provide a battery cell, a welding method for the battery cell and a battery, wherein the tab part has multiple tab layers, and the tabs of different layers are welded sequentially onto the adapter plate, a pressing part is formed between the multiple tab layers, and a welding part is formed between the multiple tab layers and the adapter plate, thereby solving the problem of incomplete welding in the welding of the tabs and the adapter plate.

[0006] To solve the above-mentioned technical problems, the present invention provides a battery cell, comprising:

[0007] At least one bare cell, each bare cell having a tab extending out, the tab including at least two tab layers;

[0008] The adapter piece has each tab welded to it. In two adjacent tab layers, from the root of the bare cell toward the end of the tab, the outer tab layer sequentially forms a pressing part and a welding part. The pressing part covers and presses onto the inner tab layer, and the welding part is welded to the adapter piece.

[0009] In one embodiment of the present invention, in two adjacent tab layers, the length of the inner tab layer extending out of the bare cell is shorter than the length of the outer tab layer extending out of the bare cell.

[0010] In one embodiment of the present invention, at least one tab is provided in each tab layer.

[0011] In one embodiment of the present invention, multiple tabs in the same tab layer extend to the same length.

[0012] In one embodiment of the present invention, the inner tab layer and the outer tab layer are welded to the pressing portion.

[0013] To address the aforementioned technical problems, the present invention also provides a method for welding a battery cell, used to weld the bare battery cell to an adapter plate or an external structural component, comprising the following steps:

[0014] S1. Weld the innermost tab layer of two adjacent tab layers to the adapter plate or outer structural component.

[0015] S2. Bend the outer tab layer of the two adjacent tab layers toward the inner tab layer, so that the outer tab layer partially covers the inner tab layer and partially protrudes from the inner tab layer. The part of the tab layer protruding from the inner tab layer is welded to the adapter piece or outer structural component.

[0016] In one embodiment of the present invention, in step S1, the inner tab layer is partially welded to the adapter piece or the outer structural component, and the effective welding length between the inner tab layer and the adapter piece or the outer structural component is less than the length of the inner tab layer extending out.

[0017] In one embodiment of the present invention, in step S2, when the outer tab layer is welded to the adapter piece or outer structural component in length order, the effective welding length of the last welded tab layer is:

[0018] l = LH

[0019] Where L is the length of the protrusion of the rear tab layer from the front tab layer, and H is the total thickness of all tab layers before the rear tab layer is welded.

[0020] In one embodiment of the present invention, in step S2, two adjacent tab layers are welded.

[0021] To address the aforementioned technical problems, the present invention also provides a battery, including the battery cell.

[0022] The technical solution of the present invention has the following advantages compared with the prior art:

[0023] The battery cell of this invention features a novel tab structure, wherein the tab portion comprises at least two tab layers, each tab layer being soldered onto an adapter plate. In adjacent tab layers, the tab layer closer to the adapter plate is the inner tab layer, and the tab layer farther from the adapter plate is the outer tab layer. From the root of the bare battery cell towards the end of the tab portion, the outer tab layer sequentially forms a pressing portion and a welding portion. The pressing portion covers and presses onto the inner tab layer, and the welding portion is soldered onto the adapter plate. Compared to existing tab structures with multiple tabs of equal length, this invention uses tab layers of different lengths, allowing each tab layer to form a welding portion with the adapter plate. Furthermore, the longer tab layers can be pressed onto the shorter tab layers, ensuring that all tab layers can contact and weld with the adapter plate, thereby solving the problem of incomplete soldering.

[0024] The welding method for the battery cell described in this invention is used to weld the aforementioned tab structure to the adapter plate or outer structural component. To ensure that all tab layers can be welded to the adapter plate or outer structural component, firstly, the inner tab layer of two adjacent tab layers is welded to the adapter plate or outer structural component; then, the outer tab layer of two adjacent tab layers is bent towards the inner tab layer, so that the outer tab layer partially covers the inner tab layer and partially protrudes from the inner tab layer. The portion of the tab layer protruding from the inner tab layer is welded to the adapter plate or outer structural component. The use of layered tab layers enables graded welding of the tab portion to the adapter plate or outer structural component, improving the welding effect, avoiding incomplete welds, and, by pressing the outer tab layer onto the inner tab layer, the position of the inner tab layer can be restricted, and the welding quality between the inner tab layer and the adapter plate or outer structural component can be guaranteed. Attached Figure Description

[0025] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0026] Figure 1 This is a schematic diagram of the battery cell structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the bare battery cell structure of the present invention;

[0028] Figure 3 This is a step diagram of the welding method for the battery cell of the present invention;

[0029] Figure 4 This is a flowchart of the welding method for the battery cell of the present invention.

[0030] Explanation of reference numerals in the accompanying drawings: 1. Bare battery cell; 11. Electrode portion; 111A. First electrode layer; 111B. Second electrode layer; 111C. Third electrode layer; 1111. Pressing part; 1112. Soldering part; 2. Adapter piece. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0032] Example 1

[0033] In the field of new energy battery production, some types of cells require adapter plates during manufacturing to connect the cell's tab structure to the battery's terminal structure, enabling current conduction. Generally, the connection between the adapter plate and the tab structure is achieved through welding, specifically using a fiber laser with a wavelength adjusted to 1030nm–1090nm. This laser welding method is feasible when the tab structure is relatively thin, and precise control of the welding temperature and time ensures welding quality. However, with the development of high-energy-density batteries, for stacked cells, the more layers there are, the higher the cell's energy density becomes. The higher the capacity, the thicker the tab structure becomes as the number of laminations increases. When using existing welding techniques, it is easy to encounter incomplete welds. For example, the negative tab structure of the battery cell is made of copper. Copper has extremely low absorption rate for laser wavelengths of 1030nm to 1090nm and dissipates heat very quickly. Therefore, extremely high power density is required for deep penetration welding, which requires extremely high equipment power during application. When the number of laminations in the negative tab structure increases, extremely high requirements are placed on the control of equipment power and welding temperature. If these requirements cannot be met, even slight changes in the defocusing amount can easily lead to incomplete welds.

[0034] To solve the above problems, refer to Figure 1 and Figure 2 As shown, the present invention discloses a battery cell, including a bare battery cell 1 and an adapter plate 2, wherein: the bare battery cell 1 has a protruding tab portion 11, the tab portion 11 being soldered onto the adapter plate 2; the tab portion 11 includes at least two tab layers, in adjacent tab layers, the tab layer relatively closer to the adapter plate 2 is the inner tab layer, and the tab layer relatively farther from the adapter plate 2 is the outer tab layer; in the direction from the root of the bare battery cell 1 toward the end of the tab portion 11, the outer tab layer sequentially forms a pressing portion 1111 and a soldering portion 1112. The pressing part 1111 covers and presses against the inner electrode layer, and the welding part 1112 is welded to the adapter piece 2. Compared with the existing multi-equal-length electrode structure, under the premise of ensuring that the number of stacked pieces in the cell remains unchanged, the electrode pieces are set to different lengths, and electrode layers of different lengths are set, so that different electrode layers can form welding parts 1112 with the adapter piece 2. The longer electrode layer can be pressed against the shorter electrode layer, ensuring that all electrode layers can contact and weld with the adapter piece 2, thereby solving the problem of poor soldering.

[0035] In this embodiment, the tab portion 11 has three tab layers, which are divided into the first tab layer 111A, the second tab layer 111B, and the third tab layer 111C according to their positional relationship with the adapter piece 2. In other embodiments, the number of tab layers can be set according to the number of electrodes in the tab portion 11, including two tab layers, four tab layers, five tab layers, etc.

[0036] Specifically, in order to ensure that the outer tab layer can form a pressing part 1111 on the inner tab layer, and at the same time protrude from the inner tab layer to form a welding part 1112, it is necessary to set that in the two adjacent tab layers, the length of the inner tab layer extending out of the bare cell 1 is shorter than the length of the outer tab layer extending out of the bare cell 1. That is, the length of the first tab layer 111A is set to L1, the length of the second tab layer 111B is set to L1+L2, and the length of the third tab layer 111C is set to L1+L2+L3.

[0037] Specifically, in actual manufacturing, the protruding lengths L1, L2, and L3 of different tab layers can be the same or different. Generally, an equal length increment setting method can be adopted, i.e., L1 = L2 = L3. This can ensure the balance of the tab portion 11 and prevent the tab layer from being too short or too long. Considering the actual welding process, during welding, since the innermost tab layer can be directly welded to the adapter piece 2, and the outermost tab layer needs to be bent towards the adapter piece 2, in order to ensure welding quality, the lengths of L1, L2, and L3 can be set as: L1 > L2 < L3. This ensures that the outermost tab layer has sufficient effective welding length after bending.

[0038] The number of tabs in each tab layer is the same. For example, if a battery cell contains 30 tabs, it can be divided into three tab layers, with 10 tabs in each layer. This ensures that the welding process used when welding each tab layer to the adapter piece 2 is basically the same. Considering the actual welding process, since the outermost tab layer needs to be bent towards the adapter piece 2 during welding, the number of tabs in the outermost tab layer can be minimized. For example, if a battery cell contains 50 tabs, it can be divided into three tab layers: 25 tabs in the first tab layer 111A, 15 tabs in the second tab layer 111B, and 10 tabs in the third tab layer 111C, decreasing sequentially to facilitate bending of the outermost tab layers.

[0039] Specifically, in this embodiment, each tab layer is provided with at least one tab piece. The number of tab pieces in different tab layers can be the same or different. Generally, an equal division method can be used to set the number of tab pieces in each tab layer to be the same. For example, if the battery cell includes a total of 30 tab pieces, it can be divided into three tab layers, with 10 tab pieces in each tab layer. This ensures that the welding process used when welding each tab layer to the adapter piece 2 is basically the same. Considering the actual welding... Regarding the process, during welding, since the outermost tab layer needs to be bent towards the adapter plate 2, the outermost tab layer can be set to have the fewest tabs. For example, if the battery cell includes a total of 50 tabs, it can be divided into three tab layers: 25 tabs in the first tab layer 111A, 15 tabs in the second tab layer 111B, and 10 tabs in the third tab layer 111C, decreasing in number to facilitate bending of the outermost tab layer.

[0040] Specifically, in this embodiment, the layering rule of different tab layers is based on the length of the tab pieces. Therefore, multiple tab pieces in the same tab layer are set to have the same extension length.

[0041] Specifically, in this embodiment, in order to further improve the welding quality, the two adjacent tab layers are also welded, that is, the inner tab layer and the outer tab layer are welded to the pressing part 1111.

[0042] Specifically, the bare battery cell 1 includes a positive electrode tab 11 and a negative electrode tab 11. Either the positive electrode tab 11 or the negative electrode tab 11 may have at least two tab layers, or both the positive electrode tab 11 and the negative electrode tab 11 may have at least two tab layers. Furthermore, depending on the actual battery cell structure, the positive electrode tab 11 and the negative electrode tab 11 may extend from the same side of the bare battery cell 1, or they may extend from different sides of the bare battery cell 1.

[0043] Example 2

[0044] Reference Figure 3 As shown, the present invention also discloses a welding method for a battery cell, used to weld the bare battery cell 1 described in Embodiment 1 to the adapter plate 2 or the outer structural component. To ensure that all tab layers can be welded to the adapter plate 2 or the outer structural component, the method specifically includes the following steps:

[0045] S1. Weld the innermost electrode layer of two adjacent electrode layers to the adapter plate 2 or the outer structural component.

[0046] S2. Bend the outer tab layer of the two adjacent tab layers toward the inner tab layer, so that the outer tab layer partially covers the inner tab layer and partially protrudes from the inner tab layer. The part of the tab layer protruding from the inner tab layer is welded to the adapter piece 2 or the outer structural component.

[0047] The use of layered tabs enables graded welding of the tab 11 to the adapter piece 2 or the outer structural component, improving the welding effect and avoiding incomplete welding. Furthermore, the outer tab layer can press against the inner tab layer, restricting the position of the inner tab layer and ensuring the welding quality between the inner tab layer and the adapter piece 2 or the outer structural component.

[0048] Reference Figure 4As shown, in this embodiment, the electrode tab 11 has three electrode tab layers, which are divided into three layers according to their distance from the adapter piece 2: a first electrode tab layer 111A, a second electrode tab layer 111B, and a third electrode tab layer 111C. Following the welding method described above, the first electrode tab layer 111A is first welded to the adapter piece 2 or the outer structural component, completing the welding action of the first electrode tab layer 111A. Then, the second electrode tab layer 111B is bent towards the first electrode tab layer 111A, so that the second electrode tab layer 111B partially covers the first electrode tab layer 111A, and... Part of the first tab layer 111A protrudes out and is welded to the adapter piece 2 or the outer structural component, thus completing the welding action of the second tab layer 111B. Similarly, the third tab layer 111C is bent toward the second tab layer 111B, so that the third tab layer 111C partially covers the second tab layer 111B and partially protrudes out of the second tab layer 111B. The part protruding out of the second tab layer 111B is welded to the adapter piece 2 or the outer structural component, thus completing the welding action of the third tab layer 111C.

[0049] To ensure that the outer tab layer can cover and partially protrude from the inner tab layer, it is necessary to set that in two adjacent tab layers, the length of the inner tab layer extending out of the bare cell 1 is shorter than the length of the outer tab layer extending out of the bare cell 1. That is, the length of the first tab layer 111A is set to L1, the length of the second tab layer 111B is set to L1+L2, and the length of the third tab layer 111C is set to L1+L2+L3.

[0050] In step S1, the inner tab layer is partially welded to the adapter piece 2 or the outer structural component. The effective welding length between the inner tab layer and the adapter piece 2 or the outer structural component is less than the length of the inner tab layer extending out: the effective welding length between the first tab layer 111A and the adapter piece 2 is set to l1. Effective welding can be achieved at any length of the first tab layer 111A, i.e., l1 < L1.

[0051] In step S2, when the outer tab layers are welded to the adapter piece 2 or the outer structural component in length order, the effective welding length of the last welded tab layer is: l = LH, where L is the length of the last tab layer protruding from the previous tab layer, and H is the total thickness of all tab layers before the last tab layer is welded; the effective welding length between the second tab layer 111B and the adapter piece 2 is set to l2. Since setting the second tab layer 111B requires bending towards the first tab layer 111A, l2 = L2 - H1 (thickness of the first tab layer 111A); similarly, the effective welding length between the third tab layer 111C and the adapter piece 2 is set to l3. Since setting the third tab layer 111C requires bending towards the second tab layer 111B and the first tab layer 111A, l3 = L3 - H1 (thickness of the first tab layer 111A) - H2 (thickness of the second tab layer 111B).

[0052] Specifically, before performing step S1, the process also includes the preparation of bare cell 1. Based on the number of stacked sheets, the number of tab layers of tab portion 11, the number of tab pieces in each tab layer, and the length of each tab layer are preset. The specific setting scheme is described in Example 1. The number of winding layers or stacked sheets is set according to the preset number of tab layers and the number of tab pieces in each tab layer. The die-cutting amount of the tab is set according to the preset length of each tab layer.

[0053] Specifically, in step S2, in order to further improve the welding quality, while welding the portion of the electrode layer protruding from the inner layer to the adapter piece 2 or the outer structural component, two adjacent electrode layers are welded.

[0054] Example 3

[0055] To address the aforementioned technical problems, the present invention also provides a battery comprising the battery cell described in Embodiment 1 above.

[0056] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A battery cell, characterized in that, include: At least one bare cell, each bare cell having a tab extending out, the tab comprising at least two tab layers; each tab layer comprising multiple tab plates; The adapter plate has each tab welded to it; and all tab layers in each tab are located on the same side of the adapter plate. In this configuration, of the two adjacent electrode layers, the inner electrode layer is designated as the first electrode layer, and the outer electrode layer is designated as the second electrode layer. The number of electrode tabs in the second electrode layer is less than the number of electrode tabs in the first electrode layer. The first tab layer includes a first welding portion, which is attached and welded to the adapter piece. The second electrode layer includes a first pressing portion and a second welding portion connected in sequence. The first holding portion covers the first welding portion, and the second welding portion is bent towards the adapter piece relative to the first holding portion. The first welding portion and the second welding portion are arranged sequentially along the width direction of the adapter piece. The second welding portion is attached to and welded to the adapter piece, and the first holding portion is welded to the first welding portion.

2. The battery cell according to claim 1, characterized in that: In the adjacent first tab layer and second tab layer, the length of the first tab layer extending out of the bare cell is shorter than the length of the second tab layer extending out of the bare cell.

3. The battery cell according to claim 1, characterized in that: The extension lengths of multiple tabs in the same tab layer are the same.

4. A method for welding a battery cell, used to weld the tab portion of the bare battery cell according to any one of claims 1 to 3 to an adapter piece, characterized in that: Includes the following steps: S1. Weld the innermost electrode layer of two adjacent electrode layers to the adapter plate; S2. Bend the outer tab layer of the two adjacent tab layers toward the inner tab layer, so that the outer tab layer partially covers the inner tab layer and partially protrudes from the inner tab layer. The part of the tab layer protruding from the inner tab layer is welded to the adapter piece.

5. The cell welding method according to claim 4, characterized in that: In step S1, the inner tab layer is partially welded to the adapter plate, and the effective welding length between the inner tab layer and the adapter plate is less than the length of the inner tab layer extending out of the bare cell.

6. The cell welding method according to claim 4, characterized in that: In step S2, when the outer tab layers are welded to the adapter pieces sequentially according to their length, the effective welding length of the last welded tab layer is: l = LH Where L is the length of the subsequent tab layer protruding from the previous tab layer, and H is the total thickness of all tab layers that have been welded before the subsequent tab layer is welded.

7. The cell welding method according to claim 4, characterized in that: In step S2, two adjacent tab layers are welded together.

8. A battery, characterized in that: Includes the battery cell as described in any one of claims 1 to 3.

Images