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 which is provided with a pole lug connecting part; the tab comprises a plurality of layers of tab monomers which are sequentially overlapped along the thickness direction of the tab, the tab is provided with a welding area and a flexible area, and the welding area is welded with the tab connecting part; the flexible region is located on one side of the welding region away from the pole group; and the flexible area is provided with an unconnected area which is not connected between two adjacent layers of tab monomers. According to the invention, the plurality of layers of tab monomers are overlapped into a whole, so that the formed tab has the same overcurrent capability as an integrally formed thick tab, and meanwhile, the tab disclosed by the invention has relatively good bending performance, and the difficulty of bending the tab to a preset position subsequently is reduced.

Description

Technical Field

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

[0002] Soft-pack batteries usually refer to batteries whose outer shell is an aluminum-plastic composite film package. Due to its advantages such as light weight, low mold opening cost and high safety, it has been widely used in the battery field.

[0003] In order to meet the current high current capacity requirements of batteries, thicker tabs are usually used. However, as the thickness of the tabs increases, the difficulty of bending the tabs will also increase, which will affect the flexibility of the subsequent assembly process. Summary of the invention

[0004] In view of this, the present invention provides a battery cell and a battery pack to solve the problem that the thick tabs have poor bending performance and affect subsequent assembly.

[0005] In a first aspect, the present invention provides a battery cell, comprising:

[0006] A pole group having a pole ear connection portion;

[0007] The pole lug comprises a plurality of pole lug monomers stacked in sequence along the thickness direction thereof, wherein the pole lug has a welding area and a flexible area, wherein the welding area is welded to the pole lug connecting portion; the flexible area is located on a side of the welding area away from the pole group; and in the flexible area, there is an unconnected area where two adjacent layers of the pole lug monomers are not connected.

[0008] Beneficial effect: The present invention stacks multiple layers of tab monomers into a whole, which not only enables the tab after forming to have the same current capacity as the one-piece thick tab, but also enables the tab of the present invention to have better bending performance, reducing the difficulty of bending the tab to a preset position later. Further, by setting an unconnected area between the multiple layers of tab monomers in the flexible zone, the flexibility of the tab can be further improved, so that not only the probability of its breakage during the bending process can be reduced, but also the operator can be more easily bend the tab to the preset position, reducing the difficulty of bending the tab and shortening the operation time. Secondly, since the bending performance of the one-piece thick tab is poor, the one-piece thick tab can only be bent within a smaller angle range. Therefore, even if the bending operation of the one-piece thick tab is completed, a large gap will be left between the free end of the one-piece thick tab and the surface in the thickness direction of the pole group, which will greatly increase the thickness of the battery cell itself. That is to say, after the battery cell is assembled into the battery pack, the battery cell occupies more space, reducing the space utilization rate inside the battery pack and affecting the energy density of the battery pack. On the other hand, the pole ear of the present application has good bending performance, so the pole ear can be bent at a larger angle, and the free end of the bent pole ear can be close to the surface in the thickness direction of the pole group. In this way, the thickness of the battery cell after the pole ear is bent can be effectively reduced to ensure that the energy density of the battery pack is not affected. In addition, the welding area on the pole ear is used to weld the pole ear connection part on the pole group, so that a firm connection can be formed between the pole ear and the pole group, ensuring that the current is smoothly transmitted between the pole ear and the pole group.

[0009] In an optional embodiment, the multiple layers of the tab monomers further have a connection area located in the flexible area, and the connection area and the unconnected area are at least one and are arranged in one or more of the following ways:

[0010] are arranged adjacent to each other along the thickness direction of the tabs;

[0011] being arranged adjacent to each other along the width direction of the pole lugs;

[0012] The pole ears are arranged adjacent to each other along the length direction.

[0013] Beneficial effect: The present invention increases the connection area in the flexible area, which can make the flexible area of ​​the tab have good bending performance and enhance the strength of the tab in the flexible area. In this way, when the tab is bent through the flexible area, the bending angle of the tab will not change greatly during the use of the battery cell, thereby improving the reliability of the battery cell.

[0014] In an optional embodiment, the connection area is a pair, and the pair of connection areas are located on opposite sides of the unconnected area; or the unconnected area is a pair, and the pair of unconnected areas are located on opposite sides of the connection area.

[0015] Beneficial effect: Regardless of the layout of the connection area and the non-connection area in the flexible area, the tab in the flexible area can have good bending performance and good structural strength.

[0016] In an optional embodiment, it further includes a packaging film with a cavity inside, and the packaging film also has a packaging edge located on the peripheral side of the cavity and sealing the cavity; the pole group and at least part of the welding area are located in the cavity.

[0017] Beneficial effects: By wrapping the packaging film on the outside of the pole group, the pole group can be completely isolated from the external environment, providing a safe and reliable sealed environment for the pole group, so that the probability of water, dust and other pollution entering the pole group can be reduced, ensuring the safety and reliability of the battery. In addition, by setting the flexible area inside the packaging edge, the protective performance of the packaging film can be used to prevent the flexible area from being corroded by the external environment, thereby extending the service life of the flexible area. In addition, when the flexible area is bent, the packaging edge will be bent together with the flexible area, so that the original length of the packaging edge will be shortened, thereby making the structure of the battery more compact. Furthermore, compared with setting the flexible area inside the packaging edge, setting the flexible area outside the packaging film, the packaging film will not cover the surface of the flexible area, so that the packaging film and the flexible area will not interfere with each other. In other words, the operator can bend the flexible area more conveniently and quickly, and at the same time, the bending operation of the flexible area will not cause the sealing of the packaging edge to fail.

[0018] In an optional embodiment, the battery cell further includes an insulating member, which is arranged around the welding area and connected to the packaging edge, the insulating member and the flexible area are spaced apart, the thickness of the flexible area is d, and the sum of the thickness of the insulating member and the pole ear is c, satisfying (0.5:1)≤d / c≤(0.8:1).

[0019] Beneficial effects: Since the tabs are usually made of metal and have no adhesive properties, by bonding the insulating member to the tabs, the tabs can be firmly connected to the package edge on the one hand; on the other hand, the gap between the tabs and the package edge can be filled and sealed to ensure the sealing of the package film to the electrode group. In addition, the thickness of the flexible area and the sum of the thickness of the insulating member and the tabs are set according to the above ratio to ensure that the insulating member does not affect the bending angle range of the tabs.

[0020] In an optional embodiment, the tab further includes an external connection area, and the external connection area is located at an end of the flexible area away from the welding area.

[0021] Beneficial effect: By setting the external connection area on the pole ear, it is convenient to connect the pole ear with the external load, so that the electric energy inside the pole group can be output to the external load through the pole ear, thereby ensuring the normal operation of the external load.

[0022] In an optional embodiment, the external connection area is bent to the surface of the packaging film through the flexible area.

[0023] Beneficial effect: Bending the external connection area of ​​the tab to the surface of the packaging film can increase the thickness of the battery cell to a minimum extent and maintain the compact structure of the battery cell.

[0024] In an optional embodiment, the dimension of the flexible zone in the length direction of the pole ear is a, and the thickness of the battery cell is b, wherein a≥b.

[0025] Beneficial effect: By setting the size of the flexible area in the length direction of the pole ear according to the above ratio, it is convenient for operators to bend the external connection area of ​​the pole ear to the surface of the pole group, thereby improving the fit between the pole ear and the pole group.

[0026] In an optional implementation, in the welding area, adjacent tab monomers are welded or connected via a conductive adhesive.

[0027] Beneficial effect: No matter which connection method is used, multiple layers of tab monomers can be connected together, so that the tab has a high-rate current capacity.

[0028] In a second aspect, the present invention further provides a battery pack, comprising:

[0029] case;

[0030] The plurality of battery cells are sequentially arranged in the shell along the thickness direction thereof.

[0031] Beneficial effect: Since the tabs in the above-mentioned battery cell have good bending performance, compared with soft-pack batteries with thick tabs, the tabs in the above-mentioned battery cell will not excessively increase the thickness of the battery cell after bending, so that the battery cell continues to maintain a relatively compact state. In this way, the shell of the battery pack can accommodate more battery cells, so that the battery pack has a higher energy density. In addition, the battery pack in the present invention also has other advantages of the above-mentioned battery cell, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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.

[0033] Figure 1 A schematic diagram of the structure of a tab according to an embodiment of the present invention;

[0034] Figure 2 This is a schematic structural diagram of a battery cell according to an embodiment of the present invention;

[0035] Figure 3 A schematic side view of a battery cell according to an embodiment of the present invention;

[0036] Figure 4 is a side view schematic diagram of another battery cell according to an embodiment of the present invention;

[0037] Figure 5 for Figure 4 A is a partial enlarged schematic diagram;

[0038] Figure 6 for Figure 1 A schematic side view of the pole ear shown in FIG.

[0039] Description of reference numerals:

[0040] 1. Pole group; 101. Pole ear connection part; 2. Pole ear; 201. Pole ear monomer; 202. Welding area; 203. Flexible area; 204. External connection area; 3. Packaging film; 301. Packaging edge; 4. Insulating member. DETAILED DESCRIPTION

[0041] 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 embodiment is a sub-embodiment of a region of the present invention, rather than an embodiment of the entire region. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present invention.

[0042] In order to solve the problem that the thick tab has poor bending performance and affects subsequent assembly, the present invention provides a battery cell and a battery pack.

[0043] Combine the following Figures 1 to 6 , describing an embodiment of the present invention.

[0044] According to an embodiment of the present invention, on the one hand, Figures 1 to 5As shown, a battery cell is provided, including: a pole group 1 and a pole ear 2.

[0045] Specifically, the pole group 1 has a pole ear connection portion 101; the pole ear 2 includes a plurality of pole ear monomers 201 stacked in sequence along its thickness direction, and the pole ear 2 has a welding area 202 and a flexible area 203, and the welding area 202 is welded to the pole ear connection portion 101; the flexible area 203 is located on the side of the welding area 202 away from the pole group 1; in the flexible area, there is an unconnected area where two adjacent layers of the pole ear monomers are not connected.

[0046] In this embodiment, the multi-layered tab monomers 201 are stacked into a whole, which not only enables the tab 2 after forming to have the same current capacity as the one-piece thick tab, but also enables the tab 2 of this embodiment to have better bending performance, reducing the difficulty of bending the tab 2 to a preset position later. Further, by setting an unconnected area between the multi-layered tab monomers 201 in the flexible area 203, the flexibility of the tab 2 can be further improved, so that not only the probability of its breakage during the bending process can be reduced, but also the operator can bend the tab 2 to the preset position more easily, reducing the difficulty of bending the tab 2 and shortening the operation time. Secondly, since the bending performance of the one-piece thick tab is poor, the one-piece thick tab can only be bent within a small angle range. Therefore, even if the bending operation of the one-piece thick tab is completed, a large gap will be left between the free end of the one-piece thick tab and the surface in the thickness direction of the pole group 1, which will greatly increase the thickness of the battery cell itself. That is to say, after the battery cells are assembled into the battery pack, the battery cells take up more space, reducing the space utilization inside the battery pack and affecting the energy density of the battery pack. On the other hand, the pole lug 2 of the present application has good bending performance, so the pole lug 2 can be bent at a larger angle, and the free end of the bent pole lug 2 can be close to the surface of the pole group 1 in the thickness direction. In this way, the thickness of the battery cell after the pole lug 2 is bent can be effectively reduced to ensure that the energy density of the battery pack is not affected. In addition, by welding the pole lug 2 to the pole lug connecting portion 101 on the pole group 1 using the welding area 202 on the pole lug 2, a firm connection can be formed between the pole lug 2 and the pole group 1, ensuring that the current is smoothly transmitted between the pole lug 2 and the pole group 1.

[0047] It should be noted that the free end of the pole ear 2 in this embodiment is the end of the pole ear 2 away from the pole group 1. In addition, the thickness direction of the pole ear 2, the thickness direction of the pole group 1 and the thickness direction of the battery cell in this embodiment are consistent, and are all Figure 3 and Figure 4 Directions shown in .

[0048] It should be supplemented that two adjacent layers of tab monomers 201 in the welding area are connected, or there may be a part of the tab monomers 201 that are not connected.

[0049] According to an embodiment of the present invention, there is also a connection area located in the flexible area 203 between the multi-layer tab monomers 201, and there is at least one connection area and an unconnected area and they are arranged in one or more of the following ways: adjacently arranged along the thickness direction of the tab 2; adjacently arranged along the width direction of the tab 2; adjacently arranged along the length direction of the tab 2. In this embodiment, by adding a connection area in the flexible area 203, the flexible area 203 of the tab 2 can have good bending performance while enhancing the strength of the tab 2 in the flexible area 203. In this way, when the tab 2 is bent through the flexible area 203, the bending angle of the tab 2 will not change in a large range during the use of the battery cell, thereby improving the reliability of the battery cell.

[0050] According to an embodiment of the present invention, the connection area is a pair, and the pair of connection areas are located on opposite sides of the unconnected area; or the unconnected area is a pair, and the pair of unconnected areas are located on opposite sides of the connection area. Regardless of the layout of the connection area and the non-connected area in the flexible area 203, the tab 2 can have good bending performance in the flexible area 203 while also having good structural strength.

[0051] Among them, compared with a pair of unconnected areas, when a pair of connected areas is adopted and the pair of connected areas are located on opposite sides of the unconnected area, it helps to provide uniform support for the pole ear 2 during the bending process and prevent the pole ear 2 from excessive bending or deformation on one side.

[0052] According to one embodiment of the present invention, Figure 2 As shown, it also includes a packaging film 3 with a cavity inside, and the packaging film 3 is also provided with a packaging edge 301 located on the periphery of the cavity and sealing the cavity; the pole group 1 and at least part of the welding area 202 are located in the cavity. By wrapping the packaging film 3 on the outside of the pole group 1, the pole group 1 can be completely isolated from the external environment, providing a safe and reliable sealed environment for the pole group 1, so that the probability of water, dust and other pollution entering the inside of the pole group 1 can be reduced, ensuring the safety and reliability of the battery cell. In addition, the flexible area 203 is arranged in the packaging edge 301, and the protective performance of the packaging film 3 can be used to prevent the flexible area 203 from being corroded by the external environment, thereby extending the service life of the flexible area 203. In addition, when the flexible area 203 is bent, the packaging edge 301 will be bent together with the flexible area 203, so that the original length of the packaging edge 301 will be shortened, thereby making the structure of the battery cell more compact.

[0053] It should be noted that the flexible area 203 in this embodiment can be located inside the packaging edge 301 or outside the packaging film 3. Compared with setting the flexible area 203 inside the packaging edge 301, setting the flexible area 203 outside the packaging film 3 will not cover the surface of the flexible area 203, so that the packaging film 3 and the flexible area 203 will not interfere with each other. In other words, the operator can bend the flexible area 203 more conveniently and quickly, and at the same time, the bending operation of the flexible area 203 will not cause the sealing failure of the packaging edge 301.

[0054] According to one embodiment of the present invention, Figure 2 and Figure 6 As shown, the battery cell also includes an insulating member 4, which is arranged around the welding area and connected to the packaging edge 301. The insulating member 4 is spaced apart from the flexible area 203. The thickness d of the flexible area 203 and the sum of the thickness of the insulating member 4 and the pole lug 2 are c, which satisfies (0.5:1)≤d / c≤(0.8:1). Since the pole lug 2 is usually made of metal and has no adhesiveness itself, by bonding the insulating member 4 to the pole lug 2, on the one hand, the pole lug 2 and the packaging edge 301 can be firmly connected together; on the other hand, the gap formed between the pole lug 2 and the packaging edge 301 can be filled and sealed to ensure the sealing of the packaging film 3 to the pole group 1. In addition, the thickness of the flexible area 203 and the sum of the thickness c of the insulating member 4 and the pole lug 2 are set according to the above ratio, which can ensure that the insulating member 4 will not affect the bending angle range of the pole lug 2.

[0055] It should be noted that the insulating member 4 in this embodiment can be but is not limited to tab glue.

[0056] According to one embodiment of the present invention, Figures 2 to 5 As shown, the pole lug 2 also includes an external connection area 204, which is located at one end of the flexible area 203 away from the welding area 202. In this embodiment, by providing the external connection area 204 on the pole lug 2, it is convenient to connect the pole lug 2 with an external load, so that the electric energy inside the pole group 1 can be output to the external load through the pole lug 2, thereby ensuring the normal operation of the external load. It should be noted that the two adjacent layers of pole lug monomers 201 in the external connection area are all connected, or there may be a partially unconnected area.

[0057] According to one embodiment of the present invention, Figure 3 and Figure 4 As shown, the external connection area 204 is bent to the surface of the packaging film 3 through the flexible area 203. In this embodiment, the external connection area 204 of the tab 2 is bent to the surface of the packaging film 3, which can increase the thickness of the battery cell to a minimum and maintain the compact structure of the battery cell.

[0058] According to one embodiment of the present invention, Figure 1 and Figure 3 As shown, the dimension of the flexible area 203 in the length direction of the pole lug 2 is a, and the thickness of the battery cell is b. Wherein, a ≥ b. The dimension of the flexible area 203 in the length direction of the pole lug 2 is set according to the above ratio, which can facilitate the operator to bend the external connection area 204 of the pole lug 2 to the surface of the pole group 1, thereby improving the fit between the pole lug 2 and the pole group 1.

[0059] Furthermore, to ensure that the outer region 204 of the tab 2 can be bent to the surface of the electrode assembly 1 , in a specific embodiment, the thickness of the tab 2 is c, where a≥1.5c.

[0060] According to one embodiment of the present invention, adjacent tab monomers 201 are welded or connected by conductive adhesive in the welding area 202. Using welding to connect two adjacent tab monomers 201 together can provide good mechanical strength, reduce the problem of delamination of the tab 2 during subsequent use, and ensure the reliability of the tab 2. Compared with welding, using conductive adhesive to connect two adjacent tab monomers 201 together is simpler and more convenient.

[0061] The following specific examples are used to illustrate that when the dimension a of the flexible area 203 in the length direction of the pole lug 2 and the thickness b of the battery cell satisfy the relationship a≥b, the pole lug 2 can be bent at a larger angle, thereby achieving the operation of bending the external connection area 204 of the pole lug 2 to the surface of the pole group 1. It should also be understood that the following embodiments are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Some non-essential improvements and adjustments made by technicians in this field based on the above content of the present application belong to the scope of protection of the present application. The specific process parameters and the like in the following embodiments are also only an example within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description of this article, and are not necessarily limited to the specific values ​​of the embodiments below.

[0062] Example 1

[0063] The width of the pole tab 2 is set to 30 mm, the thickness c of the pole tab 2 is set to 1 mm, the width a of the flexible area 203 is set to 10 mm, and the thickness b of the battery cell is set to 6 mm.

[0064] Example 2

[0065] The width of the pole tab 2 is set to 30 mm, the thickness of the pole tab 2 is set to 2 mm, the width a of the flexible area 203 is set to 10 mm, and the thickness b of the battery cell is set to 6 mm.

[0066] Example 3

[0067] The width of the pole tab 2 is set to 30 mm, the thickness of the pole tab 2 is set to 0.5 mm, the width a of the flexible area 203 is set to 10 mm, and the thickness b of the battery cell is set to 8 mm.

[0068] Example 4

[0069] The width of the pole tab 2 is set to 30 mm, the thickness of the pole tab 2 is set to 1 mm, the width a of the flexible area 203 is set to 10 mm, and the thickness b of the battery cell is set to 8 mm.

[0070] Comparative Example 1

[0071] The width of the pole tab 2 is set to 30 mm, the thickness c of the pole tab 2 is set to 1 mm, the width a of the flexible area 203 is set to 10 mm, and the thickness b of the battery cell is set to 12 mm.

[0072] Comparative Example 2

[0073] The width of the pole tab 2 is set to 30 mm, the thickness c of the pole tab 2 is set to 1.5 mm, the width a of the flexible area 203 is set to 10 mm, and the thickness b of the battery cell is set to 14 mm.

[0074] Table 1

[0075]

[0076]

[0077] From the comparison between the embodiment and the comparative example in Table 1, it can be seen that the ratio between the width a of the flexible zone 203 and the thickness b of the battery cell will affect the bending angle of the pole ear. From comparative examples 1 and 2, it can be seen that when the width a of the flexible zone 203 is smaller than the thickness b of the battery cell, the pole ear cannot be folded 180°. If the pole ear is forcibly folded, it is easy to damage the flexible zone 203 or cause the pole ear 2 to touch the corners of the electrode group 1.

[0078] According to an embodiment of the present invention, on the other hand, a battery pack is provided, comprising: a housing and a plurality of the above-mentioned battery cells.

[0079] Specifically, a plurality of the above-mentioned battery cells are arranged in sequence in the shell along the thickness direction thereof. Since the tabs 2 in the above-mentioned battery cells have good bending performance, compared with soft-pack batteries with thick tabs, the tabs 2 in the above-mentioned battery cells will not excessively increase the thickness of the battery cells themselves after bending, so that the battery cells continue to maintain a relatively compact state. In this way, the shell of the battery pack can accommodate more battery cells, so that the battery pack has a higher energy density. In addition, the battery pack in this embodiment also has other advantages of the above-mentioned battery cells, which will not be repeated here.

[0080] 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 having a pole ear connection portion; The pole lug comprises a plurality of pole lug monomers stacked in sequence along the thickness direction thereof, wherein the pole lug has a welding area and a flexible area, wherein the welding area is welded to the pole lug connecting portion; the flexible area is located on a side of the welding area away from the pole group; and in the flexible area, there is an unconnected area where two adjacent layers of the pole lug monomers are not connected.

2. The battery cell according to claim 1, characterized in that: There is also a connection area located in the flexible area between the multiple layers of the tab monomers, and the connection area and the unconnected area are at least one and are arranged in one or more of the following ways: are arranged adjacent to each other along the thickness direction of the tabs; being arranged adjacent to each other along the width direction of the pole lugs; The pole ears are arranged adjacent to each other along the length direction.

3. The battery cell according to claim 2, characterized in that: The connection regions are a pair, and the pair of connection regions are located at two opposite sides of the unconnected region; or the unconnected regions are a pair, and the pair of unconnected regions are located at two opposite sides of the connection region.

4. The battery cell according to any one of claims 1 to 3, characterized in that: It also includes a packaging film with a cavity inside, and the packaging film also has a packaging edge located on the peripheral side of the cavity and sealing the cavity; the pole group and at least part of the welding area are located in the cavity.

5. The battery cell according to claim 4, characterized in that: The battery cell also includes an insulating member, which is arranged around the welding area and connected to the packaging edge. The insulating member is spaced apart from the flexible area. The thickness of the flexible area is d, and the sum of the thickness of the insulating member and the tab is c, satisfying (0.5:1)≤d / c≤(0.8:1).

6. The battery cell according to claim 4, characterized in that: The tab further includes an external connection area, and the external connection area is located at an end of the flexible area away from the welding area.

7. The battery cell according to claim 6, characterized in that: The external connection area is bent to the surface of the packaging film through the flexible area.

8. The battery cell according to claim 7, characterized in that: The dimension of the flexible area in the length direction of the tab is a, and the thickness of the battery cell is b, wherein a≥b.

9. The battery cell according to any one of claims 1 to 3, characterized in that: In the welding area, adjacent tab units are welded or connected via conductive adhesive.

10. A battery pack, characterized in that: include: case; A plurality of battery cells according to any one of claims 1 to 9 are arranged in sequence in the casing along the thickness direction thereof.

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