Battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises a pole group, an outer tab and a packaging film. An inner tab is arranged at one end of the pole group; the outer tab is welded with the inner tab; the packaging film is hermetically coated on the outer surface of the pole group, and one end of the outer tab is exposed out of the packaging film; the length of the pole group is a, the length of the inner tab extending from the pole group is c, and c / a is more than or equal to 0.015 and less than or equal to 0.42. By reasonably limiting the proportional relation between the length of the inner tab of the battery cell and the length of the pole group, the ratio of the length c of the inner tab extending from the pole group to the length a of the pole group is controlled within the range of 0.015-0.42, so that the internal resistance of the tab can be reduced to the maximum extent, the effective utilization rate of the internal space of the battery cell is improved, and the capacity density of the battery cell is improved; the quality problems that the welding width of the inner tab and the outer tab is insufficient, the outer tab cuts the diaphragm and the like in the manufacturing process are effectively avoided, the manufacturing process yield and the production efficiency are improved, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to battery cells and battery packs. Background Art

[0002] Soft-pack lithium batteries usually refer to lithium batteries whose outer shells are encapsulated with aluminum-plastic film. Due to their many advantages such as light weight, low mold cost, great structural flexibility, high energy density, and high battery safety performance, they have been widely used in various fields such as electric vehicles, drones, smart homes, and mobile power supplies.

[0003] The battery cell tabs in the related technology have a large internal resistance, which makes it difficult to increase the capacity density of the battery cell. With the continuous improvement of market competitiveness, how to improve the energy density of the battery cell has become the key to improving the market competitiveness of products. Summary of the invention

[0004] In view of this, the present invention provides a battery cell and a battery pack to solve the problem of how to improve the energy density of the battery cell.

[0005] In a first aspect, the present invention provides a battery cell, including a pole group, an outer pole ear and a packaging film. An inner pole ear is provided at one end of the pole group; the outer pole ear is welded to the inner pole ear; the packaging film is sealed and coated on the outer surface of the pole group, and one end of the outer pole ear is exposed from the packaging film; the length of the pole group is a, and the length of the inner pole ear extending from the pole group is c, satisfying: 0.015≤c / a≤0.42.

[0006] Beneficial effect: The present invention reasonably limits the proportional relationship between the length of the inner pole ear and the length of the pole group of the battery cell, and controls the ratio of the length c of the inner pole ear extending from the pole group to the length a of the pole group within the range of 0.015 to 0.42, thereby minimizing the internal resistance of the pole ear, improving the effective utilization rate of the internal space of the battery cell, and improving the capacity density of the battery cell; at the same time, it effectively avoids quality problems such as insufficient welding width between the inner pole ear and the outer pole ear, and the outer pole ear cutting the diaphragm, thereby improving the process yield and production efficiency, reducing costs, and thus improving the market competitiveness of products.

[0007] In an optional implementation, a weld mark is formed after the inner pole ear and the outer pole ear are welded, and the width of the weld mark is e, 1.5 mm≤e≤4.0 mm.

[0008] In an optional embodiment, the distance between the first edge of the weld mark close to the electrode group and the outer electrode ear on the same side is f, and 1.0 mm≤f≤2.0 mm.

[0009] In an optional embodiment, the distance between the second edge of the weld mark away from the electrode group and the inner electrode ear on the same side is g, and 1.0 mm≤g≤2.0 mm.

[0010] In an optional implementation, the distance between the outer pole ear and the pole group is d, 2mm≤d≤4mm.

[0011] In an optional embodiment, the length of the inner tab is c=e+g+f+d.

[0012] In an optional implementation, the length a of the pole group satisfies: 30 mm≤a≤300 mm.

[0013] In an optional embodiment, the width of the pole group is b, 20 mm ≤ b ≤ 100 mm.

[0014] In an optional embodiment, the outer pole ear includes an electrode sheet and an insulating member, the insulating member is integrally formed on the electrode sheet by injection molding, the insulating member is exposed at both ends of the electrode sheet, the other end of the electrode sheet is welded to the inner pole ear, the packaging film and the insulating member are sealed by hot melt pressing, and one end of the electrode sheet is exposed from the packaging film for drawing out current.

[0015] In a second aspect, the present invention further provides a battery pack comprising the battery cell described in any one of the above technical solutions.

[0016] Beneficial effect: Since the battery pack includes the battery cell, it has the same effect as the battery cell and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 An exploded diagram of a battery cell according to an embodiment of the present invention;

[0019] Figure 2 for Figure 1 A schematic diagram of the structure of the electrode group of the battery cell shown;

[0020] Figure 3 for Figure 1 The top view of the battery cell after the electrode group and the outer electrode ear are welded;

[0021] Figure 4 for Figure 3 A partial enlarged view of the .

[0022] Description of reference numerals:

[0023] 1. Pole group; 2. Inner pole ear; 3. Outer pole ear; 31. Electrode sheet; 32. Insulating part; 4. Packaging film; 5. Welding mark. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0025] The battery cell structure mainly consists of packaging film, pole group, and outer pole ear. The pole group includes the pole group and the inner pole ear, and the outer pole ear includes the electrode sheet and the insulating part (injection molding integrated structure). The aluminum-plastic film is punched out of the cavity that accommodates the pole group by mold stamping. After the pole group is placed in the cavity, it is sealed by hot pressing the edge of the aluminum-plastic film. At the same time, during the sealing process of the packaging film, the pole ear position is hot-pressed and sealed with the insulating part of the outer pole ear to achieve the sealing of the battery cell. One end of the outer pole ear is fixed to the inner pole ear of the pole group by laser welding, and the other end is led out to the outside of the packaging film. The middle part of the outer pole ear is isolated from the shell by the insulating part, so as to lead out the current.

[0026] Combine the following Figures 1 to 4 , describing an embodiment of the present invention.

[0027] According to an embodiment of the present invention, in a first aspect, a battery cell is provided, comprising a pole group 1, an outer pole ear 3 and a packaging film 4. An inner pole ear 2 is provided at one end of the pole group 1; the outer pole ear 3 is welded to the inner pole ear 2; the packaging film 4 is sealed and coated on the outer surface of the pole group 1, and one end of the outer pole ear 3 is exposed from the packaging film 4; the length of the pole group 1 is a, and the length of the inner pole ear 2 extending from the pole group 1 is c, satisfying: 0.015≤c / a≤0.42.

[0028] The present invention reasonably limits the proportional relationship between the length of the inner pole ear 2 of the battery cell and the length of the pole group 1, that is, controls the ratio of the length c of the inner pole ear 2 extending from the pole group 1 to the length a of the pole group 1 within the range of 0.015 to 0.42, thereby minimizing the internal resistance of the pole ear, improving the effective utilization rate of the internal space of the battery cell, and improving the capacity density of the battery cell; at the same time, effectively avoiding quality problems such as insufficient welding width between the inner pole ear 2 and the outer pole ear 3 and the outer pole ear 3 cutting the diaphragm in the process, improving the process yield and production efficiency, reducing costs, and thus improving the market competitiveness of products.

[0029] In some embodiments, after the inner pole tab 2 and the outer pole tab 3 are welded, a weld mark 5 is formed, and the width of the weld mark 5 is e, 1.5 mm≤e≤4.0 mm.

[0030] like Figure 4As shown, the width e of the weld mark 5 is controlled within the range of 1.5 mm to 4.0 mm, which can meet the overcurrent requirements of the battery cell and control the production cost of the electrode group.

[0031] In some embodiments, the distance between the first edge of the weld mark 5 close to the electrode group 1 and the outer electrode ear 3 on the same side is f, and 1.0 mm≤f≤2.0 mm.

[0032] like Figure 4 As shown, the distance f between the first edge of the weld mark 5 close to the electrode group 1 and the outer electrode ear 3 on the same side is controlled within the range of 1.0 mm to 2.0 mm, ensuring that the inner electrode ear 2 will not fall off when welding the inner electrode ear 2 and the outer electrode ear 3, meeting the equipment positioning requirements, avoiding welding quality problems such as cold welding, and ensuring production yield.

[0033] In some embodiments, the distance between the second edge of the weld mark 5 away from the electrode group 1 and the inner electrode ear 2 on the same side is g, and 1.0 mm≤g≤2.0 mm.

[0034] like Figure 4 As shown, the distance g between the second edge of the weld mark 5 away from the pole group 1 and the inner pole ear 2 on the same side is controlled within the range of 1.0 mm to 2.0 mm, ensuring that the inner pole ear 2 will not fall off when the inner pole ear 2 and the outer pole ear 3 are welded, meeting the equipment positioning requirements, avoiding welding quality such as cold welding, and ensuring production yield.

[0035] In some embodiments, the distance between the outer pole ear 3 and the pole group 1 is d, 2mm≤d≤4mm.

[0036] like Figure 4 As shown, the distance d between the external pole ear 3 and the pole group 1 is controlled in the range of 2 mm to 4 mm, ensuring that there is a certain safety distance between the end of the external pole ear 3 and the pole group 1 to prevent the external pole ear 3 from cutting the diaphragm.

[0037] In some embodiments, the length of the inner tab 2 is c=e+g+f+d.

[0038] This arrangement can effectively avoid quality problems such as insufficient welding width between the inner pole ear 2 and the outer pole ear 3, and the outer pole ear 3 cutting the diaphragm during the process, improve the process yield and production efficiency, reduce costs, and thus improve product market competitiveness.

[0039] In some embodiments, the length a of the electrode group 1 satisfies: 30 mm≤a≤300 mm.

[0040] With such arrangement, the present invention is suitable for increasing the capacity density of the electrode group 1 within this length range and improving market competitiveness.

[0041] In some embodiments, the width of the electrode group 1 is b, 20 mm ≤ b ≤ 100 mm.

[0042] This arrangement improves the effective utilization of the internal space of the battery cell and increases the capacity density of the battery cell.

[0043] In some embodiments, the outer pole ear 3 includes an electrode sheet 31 and an insulating member 32. The insulating member 32 is integrally formed on the electrode sheet 31 by injection molding. The insulating member 32 is exposed at both ends of the electrode sheet 31. The other end of the electrode sheet 31 is welded to the inner pole ear 2. The packaging film 4 and the insulating member 32 are sealed by hot melt pressing. One end of the electrode sheet 31 is exposed from the packaging film 4 for drawing out the current.

[0044] In some embodiments, the packaging film 4 includes an upper shell and a lower shell, which are formed by mold stamping to form a cavity for accommodating the electrode group 1, and the electrode group 1 is placed in the cavity. The upper shell and the lower shell are then hot-pressed and sealed to seal the electrode group 1 to the packaging film 4.

[0045] In order to verify the technical effect of the present invention, a specific experimental case is provided below. The unit of each parameter is mm. Except for the parameters in the table which are variables, the rest are the same. The test results are shown in Table 1.

[0046] Table 1:

[0047]

[0048] From Table 1 we can see that:

[0049] In Case 1 and Case 2, the c / a value is greater than the specified upper limit of 0.24, which means that the tabs are too long and occupy more space in the length direction of the battery cell, which will affect the energy density of the battery cell and increase the temperature rise.

[0050] In case 10 and case 11, the c / a value is less than the specified lower limit of 0.03, which shows that the tab is short and there are many process problems, which affects the production yield. After testing multiple experimental cases 10, it was found that there were many problems with cold welding in the tab welding process, and the yield was about 0.05% lower than normal. After testing multiple experimental cases 11, it was found that there were many problems with cold welding in the tab welding process, and the yield was about 0.053% lower than normal.

[0051] In Case 3 to Case 9, the c / a value satisfies 0.03≤c / a≤0.24, the temperature rise at the battery cell ear is not much different from the temperature at other positions of the electrode group, and there are few abnormal problems in the cutting process.

[0052] According to an embodiment of the present invention, there is also provided a battery pack, comprising the battery cell described in any one of the above technical solutions.

[0053] Specifically, the battery pack includes a battery cell, and the battery cell can minimize the internal resistance of the tab, improve the effective utilization rate of the internal space of the battery cell, and improve the capacity density of the battery cell by reasonably limiting the ratio of the length of the inner tab 2 of the battery cell to the length of the pole group 1, that is, controlling the ratio of the length c of the inner tab 2 extending from the pole group 1 to the length a of the pole group 1 within the range of 0.015 to 0.42; at the same time, it can effectively avoid the quality problems such as insufficient welding width between the inner tab 2 and the outer tab 3, and the outer tab 3 cutting the diaphragm, etc., which appear in the process, improve the process yield and production efficiency, reduce costs, and thus improve the market competitiveness of the product. Therefore, it is conducive to increasing the capacity of the battery pack and improving the market competitiveness of the battery pack.

[0054] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that: include: A pole group, one end of which is provided with an inner pole ear; An outer pole ear, the outer pole ear is welded to the inner pole ear; A packaging film, wherein the packaging film is sealed and coated on the outer surface of the electrode group, and one end of the outer electrode ear is exposed from the packaging film; The length of the pole group is a, and the length of the inner pole ear extending from the pole group is c, which satisfies: 0.015≤c / a≤0.

42.

2. The battery cell according to claim 1, characterized in that: After the inner pole ear and the outer pole ear are welded, a weld mark is formed, and the width of the weld mark is e, 1.5mm≤e≤4.0mm.

3. The battery cell according to claim 2, characterized in that: The distance between the first edge of the weld mark close to the electrode group and the outer electrode ear on the same side is f, and 1.0 mm≤f≤2.0 mm.

4. The battery cell according to claim 3, characterized in that: The distance between the second edge of the weld mark away from the pole group and the inner pole ear on the same side is g, 1.0 mm≤g≤2.0 mm.

5. The battery cell according to claim 4, characterized in that: The distance between the outer pole ear and the pole group is d, 2mm≤d≤4mm.

6. The battery cell according to claim 5, characterized in that: The length of the inner tab is c=e+g+f+d.

7. The battery cell according to claim 1 or 2, characterized in that: The length a of the pole group satisfies: 30mm≤a≤300mm.

8. The battery cell according to claim 1 or 2, characterized in that: The width of the pole group is b, 20mm≤b≤100mm.

9. The battery cell according to claim 1 or 2, characterized in that: The outer pole ear includes an electrode sheet and an insulating member, the insulating member is integrally formed on the electrode sheet by injection molding, the other end of the electrode sheet is welded to the inner pole ear, the packaging film and the insulating member are sealed by hot melt pressing, and one end of the electrode sheet is exposed from the packaging film for drawing out current.

10. A battery pack, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 9.

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