Stretch-resistant tab with multi-bending elastic structure and secondary battery

Abstract

This invention relates to a tensile-resistant tab with a multi-fold elastic structure and a secondary battery. The tensile-resistant tab with the multi-fold elastic structure includes a tensile-resistant tab body, an elastic folding portion, and at least one elastic tension member. One end of the elastic folding portion is connected to the tensile-resistant tab body, and the other end is used to connect to a battery cell. The elastic folding portion has multiple bending recessed areas along the extension direction of the tensile-resistant tab body. Both ends of the elastic tension member along the extension direction of the elastic folding portion are connected to the elastic folding portion. The elastic tension member covers at least one bending recessed area so that the elastic tension member can deform synchronously with the elastic folding portion. The elastic tension member deforms synchronously with the elastic folding portion. Under the action of the elastic tension member, the tensile stress that the elastic folding portion can withstand under maximum deformation can be increased, as can the restoring ability of the elastic folding portion be improved, thereby increasing the service life of the elastic folding portion.

Description

Technical Field

[0001] This invention relates to the field of new energy battery manufacturing technology, and in particular to a tensile-resistant tab with a multi-bending elastic structure and a secondary battery. Background Technology

[0002] Most battery tabs are flat strip structures. For example, the battery module and electronic device including the battery module proposed in invention patent application number CN202180002822.1, wherein the battery unit includes a first battery and a second battery. The first battery includes a first body and a first tab, and the second battery includes a second body and a second tab. The first battery and the second battery are arranged side by side in the thickness direction of the first battery. The direction perpendicular to the thickness direction of the first battery is defined as a first direction. In the first direction, the battery unit includes a first end and a second end, and the first tab extends from the first body at the first end. The first electrode extends from the second body, and the second electrode extends from the first end of the second body; a circuit board is disposed on the outer side of the first end in a first direction, the first electrode being connected to the circuit board, and the second electrode being connected to the circuit board; and an expansion portion is disposed between the first body and the second body and / or between the first electrode and the second electrode, the expansion portion being used to generate gas by thermal decomposition or to expand under pressure to disconnect the connection between the first electrode and / or the second electrode and the circuit board; the expansion portion includes a capsule and a gas-generating material contained within the capsule; or, the expansion portion is located between the first body and the second body, the expansion portion including a capsule and a foaming agent contained within the capsule. Both the first electrode and the second electrode are of a straight strip-like structure.

[0003] The following problems exist with straight strip-shaped tabs: when the battery cell is subjected to external vibration, drops, or expansion and contraction of the electrode plates during charging and discharging, the root of the tab will bear a large tensile stress, which may cause the root of the tab to break or the welding area of ​​the tab to crack, resulting in battery failure or even safety risks.

[0004] To address the aforementioned issues, existing technologies employ adhesive tape to the surface of the tab, which effectively prevents tab breakage but fails to alleviate tensile stress within the tab. Other methods aim to counteract tensile stress without increasing the width or thickness of the tab, but this increases welding difficulty and the risk of internal short circuits. Summary of the Invention

[0005] In view of this, it is necessary to provide a tensile-resistant tab and a secondary battery with a multi-bending elastic structure to solve the problem that the existing technology cannot effectively handle the tensile stress on the tab.

[0006] On one hand, embodiments of the present invention provide a tensile-resistant tab with a multi-bending elastic structure, including a tensile-resistant tab body, an elastic folding portion, and at least one elastic tension member; one end of the elastic folding portion is connected to the tensile-resistant tab body, and the other end of the elastic folding portion is used to connect to a battery cell; the elastic folding portion has multiple bending recessed areas along the extension direction of the tensile-resistant tab body, so that the elastic folding portion can deform along the extension direction of the tensile-resistant tab body under its elastic action; both ends of the elastic tension member along the extension direction of the elastic folding portion are connected to the elastic folding portion, and the elastic tension member covers at least one of the bending recessed areas, so that the elastic tension member deforms synchronously with the elastic folding portion.

[0007] Furthermore, the elastic folding portion includes a plurality of bending units connected in sequence, the bending units being in the shape of a "V" or an arc, and a bending recessed area being formed between two adjacent bending units.

[0008] Furthermore, the elastic folding portion is in the shape of a "Z", "W" or a continuous "S" along its extension direction.

[0009] Furthermore, the elastic tension member is a double-sided adhesive layer, and both ends of the double-sided adhesive layer are bonded to the elastic fold portion.

[0010] Furthermore, both ends of the elastic tension member are respectively connected to the middle part of two adjacent bending units.

[0011] Furthermore, there are multiple elastic tension members, each corresponding to one of the multiple bending recessed areas, and each is disposed in the corresponding bending recessed area.

[0012] Furthermore, there are two elastic tension members, which are respectively disposed on both sides of the elastic folding portion, and the two elastic tension members cover multiple bending recessed areas on the corresponding sides.

[0013] Furthermore, the tensile-resistant tab body has a flat strip structure.

[0014] Furthermore, the part of the tensile-resistant tab body near the elastic fold is the tensile-resistant tab welding area.

[0015] On the other hand, embodiments of the present invention also provide a secondary battery, including the tensile-resistant tab with a multi-bending elastic structure as described above, and a cell body, wherein one end of the elastic folded portion away from the tensile-resistant tab body is connected to the cell body.

[0016] Compared with existing technologies, this tensile-resistant tab includes an elastic folding portion and at least one elastic tension member. The elastic folding portion is used to elastically connect the tensile-resistant tab body and the battery cell. Through the elastic deformation force of the elastic folding portion itself, the connection between the tensile-resistant tab body and the battery cell is achieved even when there is relative movement between them, and automatic reset between the tensile-resistant tab body and the battery cell can be achieved. At the same time, the elastic tension member deforms synchronously with the elastic folding portion. Under the action of the elastic tension member, the tensile stress that the elastic folding portion can withstand under maximum deformation and the reset capability of the elastic folding portion can be improved, thereby improving the service life of the elastic folding portion. The elastic folding portion and the elastic tension member form a multi-bending elastic structure, enabling the tensile-resistant tab to effectively cope with the tensile stress applied to it. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an existing battery; Figure 2 This is a schematic diagram of the tensile-resistant electrode lug with a multi-bending elastic structure provided in an embodiment of the present invention; Figure 3 for Figure 1 A schematic diagram of the tensile-resistant electrode tab under intermediate tensile conditions; Figure 4 This is a schematic diagram of the structure of a secondary battery provided in an embodiment of the present invention; Figure 5 for Figure 4 A schematic diagram of a secondary battery under medium tension.

[0018] Figure label: Existing battery 100, existing tab body 110, existing tab root 111, existing tab welding area 120, existing cell 120; Tensile-resistant tab 200, tensile-resistant tab body 210, elastic folding part 220, bending recessed area 221, elastic tension member 230; The secondary battery is 300, and the battery cell itself is 310. Detailed Implementation

[0019] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0020] To facilitate understanding of the intent of this invention application, the structure of existing batteries will first be described, such as... Figure 1As shown, the existing battery 100 includes an existing tab body 110 and an existing cell 120. The existing tab body 110 and the existing cell 120 are electrically connected. At the connection point between the existing tab body 110 and the existing cell 120, i.e., the root 111 of the existing tab, is a mechanically weak area. When the existing cell 120 is subjected to external vibration, drops, or expansion and contraction of the electrode during charging and discharging, the root 111 of the existing tab bears a large tensile stress, which can easily lead to the breakage of the existing tab body 110 or the cracking of the welding area 120 of the existing tab, causing battery failure or even safety risks. To solve the above problems, this invention provides a tensile-resistant tab 200 with a multi-bending elastic structure and a secondary battery 300, which will be described and explained in more detail below.

[0021] On the one hand, such as Figure 2 and Figure 3 As shown, this embodiment of the invention provides a tensile-resistant tab 200 with a multi-bending elastic structure, including a tensile-resistant tab body 210, an elastic folding portion 220, and at least one elastic tension member 230; one end of the elastic folding portion 220 is connected to the tensile-resistant tab body 210, and the other end of the elastic folding portion 220 is used to connect to the battery cell; the elastic folding portion 220 has multiple bending recessed areas 221 along the extension direction of the tensile-resistant tab body 210, so that the elastic folding portion 220 can deform along the extension direction of the tensile-resistant tab body 210 under its elastic action; both ends of the elastic tension member 230 along the extension direction of the elastic folding portion 220 are connected to the elastic folding portion 220, and the elastic tension member 230 covers at least one bending recessed area 221, so that the elastic tension member 230 deforms synchronously with the elastic folding portion 220.

[0022] Specifically, the tensile tab 200 includes an elastic folding portion 220 and at least one elastic tension member 230. The elastic folding portion 220 is used to elastically connect the tensile tab body 210 and the battery cell. Through the elastic deformation force of the elastic folding portion 220 itself, the connection between the tensile tab body 210 and the battery cell is achieved when there is relative movement between them, and automatic reset between them is also possible. At the same time, the elastic tension member 230 deforms synchronously with the elastic folding portion 220. Under the action of the elastic tension member 230, the tensile stress that the elastic folding portion 220 can withstand under maximum deformation is increased, as is the reset capability of the elastic folding portion 220, thereby increasing the service life of the elastic folding portion 220. The elastic folding portion 220 and the elastic tension member 230 form a multi-bending elastic structure, enabling the tensile tab 200 to effectively cope with the tensile stress applied to it.

[0023] In this embodiment, the tensile-resistant tab body 210 has a straight strip structure.

[0024] The tensile tab body 210 near the elastic fold 220 is the welding area of ​​the tensile tab 200. It should be noted that the welding area of ​​the tensile tab 200 should be straight and without bending.

[0025] In this embodiment, the tensile-resistant tab body 210 is typically made of aluminum foil, copper foil, or nickel-copper composite foil.

[0026] In this embodiment, the elastic folding part 220 has one end connected to the tensile tab body 210 and the other end used to connect to the battery cell. The elastic folding part 220 has multiple bending recessed areas 221 along the extension direction of the tensile tab body 210 so that the elastic folding part 220 can deform along the extension direction of the tensile tab body 210 under its elastic action.

[0027] The elastic folding part 220 includes multiple bending units connected in sequence. The bending units are in the shape of a "V" or an arc, and a bending recess area 221 is formed between two adjacent bending units.

[0028] In one embodiment, the bending angle of the multiple bending units is 5° to 175°, and the bending directions of two adjacent bending portions are opposite.

[0029] It is understood that the aforementioned elastic folding portion 220 can be formed by mechanical stamping or die cutting. The elastic folding portion 220 is a reserved extension of the tensile-resistant electrode body 210, that is, the tensile-resistant electrode body 210 and the elastic folding portion 220 are an integral structure. The elastic folding portion 220 has a compressible or stretchable folding length L1 in its natural state, and its linear length L2 after being fully unfolded satisfies: L2>L1.

[0030] In one embodiment, the elastic fold 220 is in the shape of a "Z", a "W" or a continuous "S" along its extension direction.

[0031] The working principle is as follows; When the battery cell is subjected to external force, causing the tensile tab 200 to stretch outward along its length, the bending angle of the multiple bending units of the elastic folding part 220 gradually decreases, and the elastic folding part 220 elongates as a whole, effectively preventing stress from being directly concentrated at the connection between the tensile tab body 210 and the battery cell.

[0032] When the tensile force disappears, the elastic folding part 220 automatically returns to its original length under the metal elastic memory effect of the elastic folding part 220 itself, thereby maintaining the relative position of the tensile-resistant tab body 210 and the battery cell.

[0033] In this embodiment, the elastic tension member 230 is connected to the elastic folding portion 220 at both ends along the extension direction of the elastic folding portion 220. The elastic tension member 230 covers at least one bending recessed area 221 so that the elastic tension member 230 deforms synchronously with the elastic folding portion 220.

[0034] In one embodiment, the elastic tension member 230 is a double-sided adhesive layer, and both ends of the double-sided adhesive layer are bonded to the elastic fold portion 220. The double-sided adhesive layer should have high peel strength and good flexibility.

[0035] In this embodiment, the double-sided adhesive layer uses acrylic or rubber-based pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, etc., and the thickness of the double-sided adhesive layer is 5~50μm.

[0036] In this embodiment, the installation position of the end of the elastic tension member 230 relative to the elastic folding part 220 is adjustable. Different effects can be achieved according to different installation positions, which will be described and explained in more detail below.

[0037] In one embodiment, the two ends of the elastic tension member 230 are respectively connected to the middle portion of two adjacent bending units. The elastic tension member 230 exerts a constant limiting force on the stretching and repositioning of the two adjacent bending units.

[0038] In another embodiment, the two ends of the elastic tension member 230 are respectively connected to the tips of two adjacent bending units. The elastic tension member 230 exerts a relatively small limiting force on the stretching and repositioning of the two adjacent bending units.

[0039] The installation position of the end of the elastic tension member 230 should be selected according to the actual situation.

[0040] In one embodiment, there are multiple elastic tension members 230, and each elastic tension member 230 corresponds to a multiple bending recessed area 221 and is respectively disposed in the corresponding bending recessed area 221.

[0041] In one embodiment, there are two elastic tension members 230, which are disposed on both sides of the elastic fold portion 220, and the two elastic tension members 230 cover multiple bending recessed areas 221 on the corresponding sides.

[0042] It is understandable that, apart from the double-sided adhesive layer, the aforementioned elastic tension member 230 can also be replaced by other forms of elastic insulation structures such as elastic rope.

[0043] The working principle is as follows; When the battery cell is subjected to an external force that stretches the tensile tab 200 outward along its length, the elastic tension member 230 stretches accordingly. When the tensile force disappears, the elastic tension member 230 automatically returns to its original length under the elastic memory effect of its own elasticity, thereby maintaining the relative position between the tensile tab body 210 and the battery cell.

[0044] Example 1: The tensile tab 200 is made of aluminum foil with a thickness of 15μm. The tensile tab 200 is 45 mm wide and 30 mm long. A 12 mm long section to be bent is reserved on one side near the inside of the cell.

[0045] The 12 mm section to be bent is formed by stamping with upper and lower stamping dies to form four consecutive bends: from the root, bend upwards at 45°, bend downwards at 60°, bend upwards at 45°, and bend downwards at 60°. The natural length of the tensile tab 200 after folding is 22 mm.

[0046] A layer of substrate-free acrylic double-sided tape with a thickness of 25μm (peel force ≥10 N / 25mm) is attached to the surface of the bending recess area 221 of the elastic fold 220 to fix the adjacent bending recess areas 221 locally.

[0047] The tensile-resistant tab body 210 near the elastic fold 220 retains an 18 mm straight welding area for ultrasonic or laser welding to the external positive tab.

[0048] Tensile test: Traditional flat tabs break at the base when the elongation exceeds 0.3 mm; in this embodiment, the tensile-resistant tab 200 can be stretched to 2.8 mm (equivalent to an unfolded length of about 25 mm); after the external force is removed, it automatically retracts to 22.5 mm (the difference from the original state is only 0.5 mm), and still maintains bending elasticity after 100 cycles.

[0049] Example 2: By replacing the double-sided tape with silicone pressure-sensitive adhesive and alternating the bending angles of 30° and 120°, stronger restoring force can be obtained, making it suitable for drone batteries in high-vibration environments.

[0050] On the other hand, such as Figure 4 and 5 As shown, this embodiment of the invention also provides a secondary battery 300, including a tensile tab 200 with a multi-bending elastic structure, and a cell body 310, wherein one end of the elastic folded portion 220 away from the tensile tab body 210 is connected to the cell body 310.

[0051] Compared with existing technologies: 1. Significantly reduces the peak tensile stress of the tensile tab body 210, and the tensile tab 200 can be allowed to have an elastic elongation of 20% to 50% of its original length, thereby effectively preventing the tensile tab 200 from breaking.

[0052] 2. The elastic tension member 230 not only provides the restoring force for the elastic fold 220, but also absorbs vibration energy, suppresses the relaxation and permanent plastic deformation of the elastic fold 220, and improves cycle stability.

[0053] 3. No changes are needed to the main processes of the existing 120 cell assembly line. Only bending and adhesive application processes need to be added in the electrode punching and tab preforming stages, which is easy to mass-produce.

[0054] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A stretch resistant tab having a multi-bend elastic structure, characterized by, include: Tensile-resistant electrode tab body; The elastic folding part has one end connected to the tensile-resistant tab body and the other end used to connect to the battery cell. The elastic folding part has multiple bending and recessed areas along the extension direction of the tensile-resistant tab body so that the elastic folding part can deform along the extension direction of the tensile-resistant tab body under its elastic action. At least one elastic tension member, wherein both ends of the elastic tension member along the extension direction of the elastic fold are connected to the elastic fold, and the elastic tension member covers at least one of the bending recessed areas so that the elastic tension member deforms synchronously with the elastic fold.

2. The stretch resistant multiple-bend resilient tab of claim 1, wherein, The elastic folding portion includes a plurality of bending units connected in sequence. The bending units are in the shape of a "V" or an arc, and a bending recessed area is formed between two adjacent bending units.

3. The stretch resistant multiple-bend resilient tab of claim 1, wherein, The elastic folding portion is in the shape of a "Z", "W" or a continuous "S" along its extension direction.

4. The tensile-resistant electrode lug with a multi-bending elastic structure according to claim 1, characterized in that, The elastic tension member is a double-sided adhesive layer, and both ends of the double-sided adhesive layer are bonded to the elastic fold.

5. The tensile-resistant electrode lug with a multi-bending elastic structure according to claim 2, characterized in that, The two ends of the elastic tension member are respectively connected to the middle part of the two adjacent bending units.

6. The tensile-resistant electrode lug with a multi-bending elastic structure according to claim 1, characterized in that, The number of elastic tension members is multiple, and each of the multiple elastic tension members corresponds to one of the multiple bending recess areas, and is respectively disposed in the corresponding bending recess area.

7. The tensile-resistant electrode lug with a multi-bending elastic structure according to claim 1, characterized in that, The number of elastic tension members is two, and the two elastic tension members are respectively disposed on both sides of the elastic folding part, and the two elastic tension members cover multiple bending recessed areas on the corresponding sides.

8. The tensile-resistant electrode lug with a multi-bending elastic structure according to claim 1, characterized in that, The tensile-resistant tab body has a flat strip structure.

9. The tensile-resistant electrode lug with a multi-bending elastic structure according to claim 1, characterized in that, The part of the tensile-resistant tab body near the elastic fold is the tensile-resistant tab welding area.

10. A secondary battery, characterized in that, The device includes a tensile tab with a multiple bending elastic structure as described in any one of claims 1-9, and also includes a battery cell body, wherein one end of the elastic fold portion away from the tensile tab body is connected to the battery cell body.

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