Square battery cell, battery with square battery cell and battery module with square battery cell

Abstract

The square battery cell comprises a plurality of pole groups with different tab lengths, and the plurality of pole groups are sequentially combined along the thickness direction of the battery cell; and the long tabs in the pole group are eccentrically folded towards the short tabs, the edges of the folded tabs are aligned, and then pre-welding is carried out, so that all the tabs can be covered by the pre-welding weld marks. According to the invention, a plurality of pole groups with different lengths of tabs are arranged, the tabs are sequentially combined from long to short during core combination, and the pre-welding eccentricity is arranged on the side of the long tab to the direction of the short tab during welding, so that the pre-welding print can completely cover all tabs with different lengths; by adopting the technical means, the length of the tabs after the pole group is assembled can be effectively reduced, so that the yield of a battery cell in the whole production process is improved, the loss of raw materials is reduced, and the production cost and the raw material cost are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of battery manufacturing, and in particular to a square battery cell and a battery and a battery module having the same. Background Art

[0002] In the assembly process of square thick battery cells, there are mainly two processes: stacking and winding. In the stacking process, the length of the tab is longer than that of the winding process due to the existence of pre-welding and connecting plate welding. The increase in the length of the tab will cause wrinkles in the coating of the battery cell segment, ribbons in rolling, and folding of the tab in die-cutting. The increase in the length of the tab will also increase the use of raw materials; excessive tab redundancy in the assembly stage will contact the shell, increasing safety risks. For example, the overlap of the negative tab and the shell may cause corrosion and leakage of the shell. The above abnormalities will increase the manufacturing cost of the battery cell manufacturing process and are not conducive to the development of the battery cell.

[0003] The patent announcement number is CN219998445U, and the patent name is a lithium battery pole ear structure and a lithium battery stacked core. In the existing patent technology, it is specifically disclosed that "the lithium battery pole ear structure includes a positive electrode diaphragm and a negative electrode diaphragm, both of which are rectangular in shape; the long side of the positive electrode diaphragm is provided with a first pole ear, and the long side of the negative electrode diaphragm is provided with a second pole ear; the long side of the positive electrode diaphragm is provided with at least two first pole ear lead-out positions; the long side of the negative electrode diaphragm is provided with at least two second pole ear lead-out positions." The above patent adopts a stacking assembly process. The pole ear lengths between adjacent battery cells are the same. There is a risk of excessive pole ear redundancy contacting the shell during assembly. At the same time, the redundant pole ears need to be cut in the assembly section, which increases production losses. These will increase the raw material cost of the battery cell. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to solve the problem of assembly redundancy caused by excessive length of the tabs during the assembly process of square battery cells.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A square battery cell comprises several electrode groups with different electrode tab lengths, wherein the electrode groups are sequentially assembled along the thickness direction of the battery cell; the long electrode tabs in the electrode groups are eccentrically folded toward the short electrode tabs and the edges of the electrode tabs are aligned after folding, and then pre-welded so that all the electrode tabs can be covered by the pre-welding weld marks.

[0007] The present invention sets up several groups of pole groups with different pole tab lengths, and when assembling the cores, the pole groups are assembled in order from long to short. When welding, a pre-welding eccentricity is set on the long pole tab side toward the short pole tab to ensure that the pre-welding weld mark can completely cover all pole tabs of different lengths. The above technical means can effectively reduce the pole tab length of this pole group after assembly, thereby improving the yield of the entire battery cell production process, reducing raw material loss, and reducing production costs and raw material costs.

[0008] As a further solution of the present invention: let the eccentric height in the thickness direction of the electrode group be H1, where H1=0.5*H3+W0-L0;

[0009] Where H3 is the width of the outer cover of the battery cell, L0 is the pre-welding height, and W0 is the distance from the edge of the outer cover of the battery cell to the battery cell.

[0010] As a further solution of the present invention: the value range of the pre-welding height L0 is 1 mm to 6 mm.

[0011] As a further solution of the present invention, there are three electrode groups, wherein the lengths of the electrode tabs of the three electrode groups extending beyond the diaphragm are L3, L2, and L1, respectively, from longest to shortest.

[0012] As a further solution of the present invention, the three electrode groups have the same thickness, but the lengths of the electrode tabs extending beyond the separator are different.

[0013] As a further solution of the present invention: the length relationship of the three sets of electrode tabs extending beyond the diaphragm is: L1 <L2<L3。

[0014] As a further solution of the present invention: the length of the pole ear of the pole group located in the middle is

[0015]

[0016] Where H2 is the thickness of a single pole group.

[0017] As a further solution of the present invention: the length of the tab of the electrode group located below is

[0018] The present invention also discloses a battery, comprising two sets of the above-mentioned square battery cell pole groups and a battery cell shell, wherein the battery cell pole groups are installed in the battery cell shell.

[0019] The invention also discloses a battery module, which includes several groups of batteries.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides several electrode groups with different tab lengths, and when assembling the cores, the cores are assembled in order from the longest to the shortest. When welding, a pre-welding eccentricity is set on the long tab side toward the short tab to ensure that the pre-welding weld mark can completely cover all tabs of different lengths. The above technical means can effectively reduce the tab length of the assembled electrode group, thereby improving the quality rate of the entire battery cell production process.

[0022] The above-mentioned technical means can be used to reversely deduce the lengths of the short and middle tabs located below the longest tab, which can effectively reduce the length of the tabs after assembly of the electrode group while ensuring that all weld marks are covered. This application reduces raw material loss, production costs, and raw material costs by changing the stacking method and assembly method of the electrode group. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of a long-pole and ear-pole group according to embodiment 1 of the present invention;

[0024] Figure 2 for Figure 1 Side view of;

[0025] Figure 3 Schematic diagram of the structure of the tab electrode group in Example 1 of the present invention;

[0026] Figure 4 for Figure 3 Side view of;

[0027] Figure 5 This is a schematic structural diagram of a short tab electrode group according to embodiment 1 of the present invention;

[0028] Figure 6 for Figure 5 Side view of;

[0029] Figure 7 This is a schematic diagram of a core with three pole groups assembled according to Example 4 of the present invention;

[0030] Figure 8 This is a schematic diagram of pre-welding after three pole groups are assembled into a core according to Example 4 of the present invention;

[0031] Figure 9 This is a diagram showing the positional relationship between two groups of battery cells and the cover plate during pre-welding according to an embodiment of the present invention;

[0032] Figure 10 for Figure 9 A partial enlarged view of

[0033] Figure 11 This is a diagram showing the positional relationship of two groups of battery cells after folding according to an embodiment of the present invention;

[0034] Description of reference numerals:

[0035] 1. Long electrode group; 11. Long electrode group positive electrode tab; 12. Long electrode group negative electrode tab; 13. Long electrode group diaphragm; 14. Long electrode group negative electrode; 15. Long electrode group positive electrode; 16. Long electrode group tape;

[0036] 2. Middle electrode group; 21. Middle electrode group positive electrode tab; 22. Middle electrode group negative electrode tab; 23. Middle electrode group separator; 24. Middle electrode group negative electrode; 25. Middle electrode group positive electrode; 26. Middle electrode group tape;

[0037] 3. Short pole lug group; 31. Short pole lug group positive pole lug; 32. Short pole lug group negative pole lug; 33. Short pole group diaphragm; 34. Short pole group negative pole; 35. Short pole group positive pole; 36. Short pole group tape;

[0038] 4. Battery cover. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0040] Example 1

[0041] Reference Figure 7 and Figure 8 A square battery cell includes three groups of pole groups with different pole tab lengths, namely a long pole tab pole group 1, a medium pole tab pole group 2 and a short pole tab pole group 3. The three pole groups are sequentially connected in the thickness direction in the order of the pole tab length from long to short (such as Figure 7 shown).

[0042] The short pole ear pole group 3 is located at the bottom, the long pole ear pole group 1 is located at the top, and the medium pole ear pole group 2 is located between the short pole ear pole group 3 and the long pole ear pole group 1; or the short pole ear pole group 3 is located at the top, the long pole ear pole group 1 is located at the bottom, and the medium pole ear pole group 2 is located between the short pole ear pole group 3 and the long pole ear pole group 1; the specific arrangement depends on the actual situation and is not limited in this application.

[0043] It should be noted that, in the present application, the long tab pole group 1, the medium tab pole group 2 and the short tab pole group 3 are consistent in length, width and thickness except for the different tab lengths.

[0044] Reference Figure 1 and Figure 2The long pole group 1 includes a long pole group diaphragm 13 and a long pole group negative electrode 14 and a long pole group positive electrode 15 located above the long pole group diaphragm 13. The long pole group diaphragm 13, the long pole group negative electrode 14 and the long pole group positive electrode 15 are fixed by a long pole group tape 16; a long pole group negative pole ear 12 is provided at one end of the long pole group negative electrode 14, and a long pole group positive pole ear 11 is provided at one end of the long pole group positive electrode 15, wherein the long pole group positive pole ear 11 and the long pole group negative pole ear 12 are located on the same side and have the same length.

[0045] Reference Figure 3 and Figure 4 The middle electrode tab group 2 includes a middle electrode group diaphragm 23 and a middle electrode group negative electrode 24 and a middle electrode group positive electrode 25 located above the middle electrode group diaphragm 23. The middle electrode group diaphragm 23, the middle electrode group negative electrode 24 and the middle electrode group positive electrode 25 are fixed by a middle electrode group tape 26; a middle electrode group negative electrode tab 22 is provided at one end of the middle electrode group negative electrode 24, and a middle electrode group positive electrode tab 21 is provided at one end of the middle electrode group positive electrode 25, wherein the middle electrode group positive electrode tab 21 and the middle electrode group negative electrode tab 22 are located on the same side and have the same length.

[0046] Reference Figure 5 and Figure 6 The short pole group 3 includes a short pole group diaphragm 33 and a short pole group negative electrode 34 and a short pole group positive electrode 35 located above the short pole group diaphragm 33. The short pole group diaphragm 33, the short pole group negative electrode 34 and the short pole group positive electrode 35 are fixed by a short pole group tape 36; a short pole group negative electrode ear 32 is provided at one end of the short pole group negative electrode 34, and a short pole group positive electrode ear 31 is provided at one end of the short pole group positive electrode 35, wherein the short pole group positive electrode ear 31 and the short pole group negative electrode ear 32 are located on the same side and have the same length.

[0047] Reference Figure 8 After the core is closed, a pre-welding eccentric is set on one side of the long pole ear. The eccentric direction is from the long pole ear to the short pole ear to ensure that all pole ears can be welded to the cover battery cover 4 and covered by the weld mark. Due to the eccentricity towards the short pole ear, one of the short pole ears must be in a horizontal state instead of a folded state (reference Figure 8 There is a short horizontal ear in the middle); Figure 8 Since the long pole ear is located at the top and the short pole ear is located at the bottom, the eccentric direction is from top to bottom; on the contrary, if the long pole ear is located at the bottom and the short pole ear is located at the top, the eccentric direction is from bottom to top.

[0048] Further, let the height of the pre-welding eccentricity be H1, the pre-welding positioning height be L0, the width of the outer cover plate of the battery cell be H3, and W0 be the distance from the edge of the battery cell cover plate to the battery cell. It should be noted that after the two groups of battery cells are vertically folded, the battery cells are covered by the battery cover plate and the housing outside the battery cells; among them, the height of the pre-welding eccentricity can be calculated through the pre-welding positioning height L0 and the width H3 of the battery cell cover plate. Specifically, the height of the pre-welding eccentricity H1 = 0.5 * H3 + W0 - L0.

[0049] Furthermore, the value of the pre-welding positioning height L0 is 1 mm;

[0050] Furthermore, the range of the distance from the edge of the battery cell cover plate to the battery cell is 0 - 1 mm.

[0051] Refer to Figure 7 , the lengths by which the positive electrode tab 11 and the negative electrode tab 12 of the long electrode group exceed the long electrode group separator 13 are both L3; the lengths by which the positive electrode tab 21 and the negative electrode tab 22 of the middle electrode group exceed the middle electrode group separator 23 are both L2; the lengths by which the positive electrode tab 31 and the negative electrode tab 32 of the short electrode group exceed the short electrode group separator 33 are both L1; where L1 < L2 < L3; L1 is the conventional length of the current electrode group. Taking a square aluminum shell battery cell as an example, the tab length is generally 10 mm - 50 mm.

[0052] Refer to Figure 7 and Figure 8 , the length L2 of the tab of the middle electrode group can be calculated using the height H1 of the pre-welding eccentricity, the pre-welding positioning height L0, L1, and the thickness H2 of a single electrode group;

[0053] where

[0054] Refer to Figure 7 and Figure 8 , the length L3 of the tab of the longest electrode group can be calculated using the height H1 of the pre-welding eccentricity, the pre-welding positioning height L0, and L1;

[0055] where

[0056] Therefore, through the above technical means, the lengths of the short tab and the middle tab below the longest tab can be deduced in reverse. While ensuring that all the welding marks are covered, the tab length after the assembly of this electrode group can be effectively reduced, thereby reducing the raw material loss, production cost, and raw material cost.

[0057] Example 2

[0058] Others are the same as Example 1, the difference is that in this example, the value of the pre-welding positioning height L0 is changed to 3.5 mm.

[0059] Example 3

[0060] Other aspects are the same as those of Example 1, except that, in this embodiment, the value of the pre-welding positioning height L0 is changed to 6 mm.

[0061] Example 4

[0062] This embodiment discloses a battery comprising two sets of square cells in embodiment 1, a battery cover 4 and a battery shell (such as Figure 9 and Figure 10 ), where two groups of square cells are folded after the tabs are welded to the cover (e.g. Figure 11 ), and then installed into the battery cell housing.

[0063] Example 5

[0064] This embodiment discloses a battery module, comprising at least two groups of batteries according to embodiment 4.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A square battery cell, characterized in that: It includes several pole groups with different pole tab lengths, and several pole groups are sequentially combined along the thickness direction of the battery cell; the long pole tabs in the pole group are eccentrically folded toward the short pole tabs and the edges of the pole tabs are aligned after folding, and then pre-welded so that all pole tabs can be covered by the pre-welding weld marks.

2. A square battery cell according to claim 1, characterized in that: Let the eccentric height in the thickness direction of the electrode group be H1, where H1 = 0.5*H3+W0-L0; Where H3 is the width of the outer cover of the battery cell, L0 is the pre-welding height, and W0 is the distance from the edge of the outer cover of the battery cell to the battery cell.

3. A square battery cell according to claim 2, characterized in that: The value range of the pre-welding height L0 is 1mm to 6mm.

4. The square battery cell according to claim 2, characterized in that: There are three groups of pole groups, among which the lengths of the pole ears of the three groups extending beyond the diaphragm are L3, L2 and L1 from longest to shortest.

5. The square battery cell according to claim 4, characterized in that: The thickness of the three electrode groups is the same, but the lengths of the electrode tabs extending beyond the diaphragm are different.

6. The square battery cell according to claim 5, characterized in that: The length relationship of the three sets of pole ears beyond the diaphragm is: L1 <L2<L3。 7. The square battery cell according to claim 4, characterized in that: The length of the tab of the battery cell in the middle Where H2 is the thickness of a single pole group.

8. The square battery cell according to claim 4, characterized in that: The length of the tab of the battery cell located below 9. A battery, characterized in that: The battery comprises two groups of square battery cells and a battery shell as described in any one of claims 1 to 8, wherein the two groups of square battery cells are folded and installed in the battery shell.

10. A battery module, characterized in that: The device comprises several groups of batteries as claimed in claim 9.

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