Square battery cell

Abstract

The utility model discloses a square battery cell, which belongs to the field of lithium batteries and comprises a battery cell body, and both ends of the battery cell body comprise a plurality of tab bundles; the plurality of tab bundles located at the same end are arranged in a staggered manner in the thickness direction of the battery cell body, and the adjacent tab bundles are arranged at intervals in the width direction of the battery cell body. The utility model has the beneficial effects that the tab welding stability in the battery cell production process is ensured; burrs on the edge of the cut tab are reduced; the tab tearing risk in the shaping process is reduced; and foil scrapping in the production process is reduced.

Description

Technical Field

[0001] This utility model relates to a lithium battery, and more particularly to a square battery cell. Background Technology

[0002] Lithium-ion batteries are among the fastest-growing sectors in the new energy industry, particularly in digital products and the automotive sector. Currently, lithium-ion batteries are increasingly used in the automotive and energy storage industries, and their applications are becoming more diversified over time. Energy storage requires battery cells with high capacity to meet the demands of extended use.

[0003] like Figure 1a - Figure 1f As shown, in the prior art, a battery cell includes multiple positive and negative electrode plates, which are stacked sequentially along the thickness direction of the cell. The tabs of the positive and negative electrode plates overlap in the thickness direction, forming a tab bundle 12' at one end of the cell. The tab bundle 12' is then pressed and shaped by a shaping component moving along the length direction of the cell, thereby forming a... Figure 1b The shape shown. After the shaping is completed, as... Figure 1c As shown, the tab convergence width is L1, the position difference between the uppermost and lowermost tab ends after shaping is L2, and the total tab thickness after convergence is H1. After shaping, spot welding assemblies are used to weld the tab bundle at designated positions, such as... Figure 1d As shown, welding area 13' is formed. Figure 1e As shown, after welding, the excess tabs are trimmed, with a scrap length of L3. Figure 1f As shown, the tab bundle 12' is finally welded to the cover plate assembly 2'.

[0004] To meet the demand for high capacity, the structure requires an increase in cell thickness and the number of cell layers. As the thickness increases, many technical problems arise during the manufacturing process, such as excessive cell thickness leading to tearing and redundancy in the tab forming; too many tab layers causing large fluctuations in the weld depth after the tab cover is welded; and an increase in the total thickness of the tabs due to the increased number of electrode layers, resulting in cutting defects.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this utility model and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Utility Model Content

[0006] The technical problem to be solved by this utility model is: how to solve the problems of forming tearing, large fluctuation of welding penetration and cutting defects caused by the increase of electrode thickness due to the increase of battery cell thickness.

[0007] This utility model solves the above-mentioned technical problems through the following technical means:

[0008] A square battery cell includes a battery cell body, with multiple tab bundles at both ends of the battery cell body. The multiple tab bundles are staggered along the thickness direction of the battery cell body, and adjacent tab bundles are spaced apart along the width direction of the battery cell body.

[0009] In this invention, all the tabs are divided into sections and multiple tab bundles are set up. Compared with the same number of tab layers that are only gathered into one tab bundle, the tab gathering width of each tab bundle, the difference in the position of the top and bottom tab ends after shaping, and the total thickness of the tabs after gathering are all reduced, which is beneficial to subsequent welding and cutting processes. This ensures stable tab welding during the cell production process, reduces burrs on the tab edges after cutting, reduces the risk of tab tearing during shaping, and reduces foil scrap during the production process.

[0010] Preferably, the tab bundle includes multiple tabs, and the tabs in the same tab bundle are stacked sequentially along the thickness direction of the cell body.

[0011] Preferably, the electrodes in the same electrode bundle have the same shape, size and position, and the projections of the electrodes in the same electrode bundle on the horizontal plane overlap after being stacked sequentially.

[0012] Ensure reliable connection between the electrodes.

[0013] Preferably, each tab bundle includes multiple positive or negative electrode plates. The positive electrode plates in the same tab bundle have the same tab position, the negative electrode plates in the same tab bundle have the same tab position, the positive electrode plates in different tab bundles have different tab positions, and the negative electrode plates in different tab bundles have different tab positions.

[0014] Preferably, the thickness of the different tab bundles does not differ by more than 10%.

[0015] Preferably, the lengths of the different electrode bundles differ by no more than 10%.

[0016] Preferably, the width of the different electrode bundles does not differ by more than 10%.

[0017] Preferably, both ends of the battery cell body include two tab bundles, and the two tab bundles located at the same end are arranged in a stepped manner.

[0018] Preferably, both ends of the battery cell body include three tab bundles, and the three tab bundles located at the same end are arranged in a stepped manner.

[0019] Preferably, the tab bundles at both ends of the battery cell body are arranged symmetrically.

[0020] The advantages of this utility model are:

[0021] This invention employs a method of dividing all the tabs into sections and setting up multiple tab bundles. Compared to the case where the same number of tab layers are only gathered into one tab bundle, the tab gathering width of each tab bundle, the difference in the position of the top and bottom tab ends after shaping, and the total thickness of the tabs after gathering are all reduced, which is beneficial for subsequent welding and cutting processes. This ensures stable tab welding during the cell production process, reduces burrs on the tab edges after cutting, reduces the risk of tab tearing during shaping, and reduces foil scrap during the production process. Attached Figure Description

[0022] Figure 1a This is a top view of a battery cell in the existing technology;

[0023] Figure 1b This is a schematic diagram of the ear loop shaping process in the prior art;

[0024] Figure 1c This is a front view of the ear bundle after shaping in the prior art;

[0025] Figure 1d This is a schematic diagram of electrode bundle welding in the existing technology;

[0026] Figure 1e This is a schematic diagram of the electrode bundle cutting in the existing technology;

[0027] Figure 1f This is a schematic diagram of the welding of the tab bundle and the cover plate assembly in the prior art;

[0028] Figure 2 This is a top view of a square battery cell according to an embodiment of this utility model;

[0029] Figure 3 A perspective view of the square battery cell in Embodiment 1 of this utility model;

[0030] Figure 4 This is a front view of the tab bundle of the square battery cell after shaping in Embodiment 1 of this utility model;

[0031] Figure 5 This is a schematic diagram of the electrode bundle welding of the square battery cell in Embodiment 1 of this utility model;

[0032] Figure 6 This is a schematic diagram of the tab bundle cutting of the square battery cell in Embodiment 1 of this utility model;

[0033] Figure 7 This is a schematic diagram of the welding of the tab bundle and cover plate assembly of the square battery cell in Embodiment 1 of this utility model;

[0034] Figure 8 This is a schematic diagram of the positive electrode plate in the square battery cell of Embodiment 1 of this utility model;

[0035] Figure 9This is a schematic diagram of the positive electrode plate in the square battery cell of Embodiment 1 of this utility model;

[0036] Figure 10 This is a schematic diagram of the negative electrode plate in the square battery cell of Embodiment 1 of this utility model;

[0037] Figure 11 This is a schematic diagram of the negative electrode plate in the square battery cell of Embodiment 1 of this utility model;

[0038] Figure 12 This is a perspective view of the square battery cell in Embodiment 2 of this utility model;

[0039] Numbering on the map:

[0040] Figures 1a-1f Middle: 12', tab bundle; 13', welding area; 2', cover plate assembly;

[0041] Figures 8-12 In the middle: 1. Square cell; 11. Cell body; 12. Electrode bundle; 13. Welding area; 14. Positive electrode plate; 15. Negative electrode plate; 2. Cover plate assembly;

[0042] 12a, 12b, 12c, 12e, and 12d represent the pole ear bundles at different positions;

[0043] 14a and 14b represent positive electrode plates with different tab positions;

[0044] 15a and 15b represent negative electrode plates with different tab positions. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below in conjunction with the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0046] Example 1:

[0047] like Figure 2 , Figure 3As shown, a square battery cell 1 includes a battery cell body 11. Both ends of the battery cell body 11 include multiple tab bundles 12. The multiple tab bundles 12 located at the same end are staggered along the thickness direction of the battery cell body 11, and adjacent tab bundles 12 are spaced apart along the width direction of the battery cell body. In this embodiment, the length direction of the battery cell body 11 is taken as the X direction, the width direction as the Y direction, and the thickness direction as the Z direction. In this embodiment, "ends" refers to both ends along the length direction.

[0048] It should be noted that, in this embodiment, the staggered arrangement along the thickness direction of the cell body 11 and the adjacent tab bundles 12 spaced apart in the width direction refer to... Figure 3 As shown, the projection of the left-side tab bundle 12a onto the horizontal plane is completely different from the projection of the right-side tab bundle 12b onto the horizontal plane. Furthermore, the tab bundles 2a and 2b are located at different heights. The uppermost tab of the tab bundle 2a and the lowermost tab of the tab bundle 2b are separated by a diaphragm. The projections of the tab bundles 2a and 2b onto the vertical plane are also completely different.

[0049] In this embodiment, each end of the battery cell body 11 includes two tab bundles 12, and the tab bundles 12 at both ends can be distributed symmetrically along the vertical symmetry plane in the middle of the battery cell body 11.

[0050] like Figure 3 As shown, each tab bundle 12 includes multiple tabs. The shape, size and position of each tab within the same tab bundle 12 are basically the same. Multiple tabs within the same tab bundle 12 are stacked along the thickness direction of the cell body 11, and the projections of the tabs of each tab bundle 12 on the horizontal plane after stacking are basically coincident. Basically coincident means that the area of ​​the overlapping part accounts for more than 95% of the area of ​​the tab.

[0051] The thickness, length, and width of all tab bundles 12 do not differ by more than 10%. For example, in this embodiment, assuming the thickness of tab bundle 12a is 10mm, then the thickness of tab bundle 12b cannot exceed 11mm or be less than 9mm, and the length and width follow the same principle. This ensures that the final structure of the tab bundles after shaping is not significantly different. Preferably, all tab bundles 12 have the same thickness, length, and width.

[0052] like Figure 4As shown, the tabs are shaped by using a shaping device with the bottom surface of the cell body 11 as the reference plane, pressing the tabs downwards to gather all the tabs towards the bottom surface. After shaping, the tab gathering width is L1*, the difference in position between the top and bottom tab ends after shaping is L2*, and the total thickness of the gathered tabs is H1*. The dimensions after tab shaping in the prior art are compared as follows: tab gathering width L1 ≈ 2 times L1*; the difference in position between the top and bottom tab ends after shaping L2 ≈ 2 times L2*; the total thickness of the gathered tabs H1 ≈ 2 times H1*. It can be seen that all dimensions are reduced after adopting this embodiment.

[0053] It should be noted that the above-mentioned tab folding width, the difference in position between the top and bottom tab ends after shaping, and the total thickness of the tab after folding are all about twice the value. This two times is just a reference value and a deviation of 10% is allowed.

[0054] like Figure 5 As shown, after the shaping is completed, the electrode bundle 12 is welded at the designated position using a spot welding assembly to form a welding area 13. In this embodiment, the electrode bundle is thin after being gathered, so the electrode delamination problem is not easy to occur, and the flat welding stability is strong.

[0055] like Figure 6 As shown, after welding, the scrap is cut to a length of L3*. Compared with the prior art, the scrap length L3≈2L3*, and a 10% error is allowed. When there are too many tab layers, cutting becomes more difficult, burrs are produced, and the pass rate decreases. In this embodiment, because the thickness of each tab bundle 12 is reduced, it can be cut smoothly, the length of the scrap is shortened, and the blockage of the scrap collection port is reduced.

[0056] like Figure 7 As shown, after cutting, the tab bundle 12 is welded to the cover plate assembly 2. Since there is an upper limit to the welding thickness, a thinner tab bundle 12 helps reduce incomplete welds. In this embodiment, the multi-position tab bundle 12 has less weld penetration fluctuation after welding than the single-position tab bundle 12', reducing the risk of incomplete welds and over-welding.

[0057] This embodiment includes two pole ear bundles 12, combined with Figures 8-11 As shown, each tab bundle 12 still includes multiple positive electrode plates 14a, 14b or negative electrode plates 15a, 15b. The positions of the tabs on the positive electrode plates 14a and 14b in different tab bundles 12 are different, as are the positions of the tabs on the negative electrode plates 15a and 15b in different tab bundles 12. The positions of the tabs on the positive electrode plates 14a and the negative electrode plates 15a within the same tab bundle 12 are the same. Figure 8 As shown, the tab of the positive electrode 14a is located on the upper half of one end side, as... Figure 9 As shown, the tab of the positive electrode 14b is located on the lower half of one end side, as... Figure 10 As shown, the tab of the negative electrode 15a is located on the upper half of one end side, as... Figure 11 As shown, the tab of the negative electrode 15b is located in the lower half of one end. Then, multiple positive electrode 14a are stacked in the same tab bundle 12, multiple positive electrode 14b are stacked in the same tab bundle 12, multiple negative electrode 15a are stacked in the same tab bundle 12, and multiple negative electrode 15b are stacked in the same tab bundle 12.

[0058] In this embodiment, the tab bundles 12 located at the same end have the same polarity.

[0059] The positive electrode 14a and the positive electrode 4b are preferably the same in shape and size, and the negative electrode 15a and the negative electrode 15b are preferably the same in shape and size. Maintaining consistency in shape and size facilitates subsequent processes.

[0060] Therefore, this embodiment, by setting multiple tab bundles 12 and dividing all the tabs into sections, reduces the tab width of the tab bundle 12, the difference in the position of the top and bottom tab ends after shaping, and the total thickness of the tabs after gathering, compared to the case where the same number of tab layers are only gathered into one tab bundle 12'. This is beneficial for subsequent welding and cutting processes. This ensures stable tab welding during cell production; reduces burrs on the tab edges after cutting; reduces the risk of tab tearing during shaping; and reduces foil scrap during production.

[0061] Example 2:

[0062] like Figure 12 As shown, the difference between this embodiment and Embodiment 1 is that the number of electrode bundles 12 is different.

[0063] In this embodiment, there are three tab bundles 12 located at the same end. The three tab bundles 12 are arranged alternately along the thickness direction of the cell body 11, and adjacent tab bundles 12 are arranged at intervals in the width direction.

[0064] In this embodiment, the three tab bundles 12 are arranged in a stepped manner, with the leftmost tab bundle 12c located at the bottom, the middle tab bundle 12d located in the middle position, and the rightmost tab bundle 12e located at the top. Similarly, each tab bundle 12 includes multiple tabs, which are stacked and arranged in a manner that results in their projections onto the horizontal plane being essentially the same.

[0065] After shaping, the tab width is L1**, the position difference between the top and bottom tab ends is L2**, and the total tab thickness after shaping is H1**. The dimensions after tab shaping are compared with those in existing technologies as follows: tab width L1 ≈ 3 times L1**; position difference between the top and bottom tab ends L2 ≈ 3 times L2**; total tab thickness after shaping H1 ≈ 3 times H1**.

[0066] After shaping, spot welding is used to weld the tab bundle 12 at designated positions. After welding, the scrap is cut off, with a scrap length of L3**. Scrap length L3≈3L3**.

[0067] It can be seen that as the number of tab bundles 12 increases, the tab width of the tab bundle, the difference in position between the top and bottom tab ends after shaping, and the total thickness of the tabs after gathering all decrease, which is beneficial for subsequent welding and cutting processes.

[0068] Based on the above embodiment 1 and this embodiment, it can be expanded to four electrode bundles 12. The specific number of electrode bundles 12 can be selected according to actual production needs.

[0069] In this embodiment, the positive electrode 14 or negative electrode 15 can be processed according to the three different positions of the tab bundles 12c, 12d, and 12e.

[0070] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A square battery cell, characterized in that, The battery cell body includes multiple tab bundles at both ends; the multiple tab bundles located at the same end are staggered along the thickness direction of the battery cell body, and adjacent tab bundles are spaced apart along the width direction of the battery cell body.

2. A square battery cell according to claim 1, characterized in that, A tab bundle includes multiple tabs, and the tabs in the same tab bundle are stacked sequentially along the thickness direction of the cell body.

3. A square battery cell according to claim 1 or 2, characterized in that, The electrodes within the same electrode bundle have the same shape, size, and position, and their projections on the horizontal plane overlap after being stacked sequentially.

4. A square battery cell according to claim 1, characterized in that, Each tab bundle includes multiple positive or negative electrodes. Positive electrodes within the same tab bundle have the same tab position, as do negative electrodes within the same tab bundle. Positive electrodes within different tab bundles have different tab positions, as do negative electrodes within different tab bundles.

5. A square battery cell according to claim 1, characterized in that, The thickness of the different ear bundles does not differ by more than 10%.

6. A square battery cell according to claim 1, characterized in that, The lengths of the different ear bundles do not differ by more than 10%.

7. A square battery cell according to claim 1, characterized in that, The width of the different ear bundles does not differ by more than 10%.

8. A square battery cell according to claim 1, characterized in that, Both ends of the battery cell body include two tab bundles, and the two tab bundles located at the same end are arranged in a stepped manner.

9. A square battery cell according to claim 1, characterized in that, Both ends of the battery cell body include three tab bundles, and the three tab bundles located at the same end are arranged in a stepped manner.

10. A square battery cell according to claim 1, characterized in that, The tab bundles at both ends of the battery cell are arranged symmetrically.

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