Tab connecting device and battery pack

Abstract

The utility model relates to battery technical field discloses a kind of tab connecting device, comprising: substrate, foldable formation puncture surface and receiving surface, puncture surface and receiving surface are oppositely arranged;Puncture portion is set on puncture surface;Recess portion is set on receiving surface, recess portion and puncture portion are correspondingly arranged, the top end of puncture portion and the bottom end of recess portion abut, the utility model can strengthen the welding firmness of multilayer tab.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a tab connection device and a battery pack. Background Technology

[0002] Currently, composite foil current collectors are attracting attention in the industry as a novel type of electrode. Composite foil current collectors have a three-layer structure, including an intermediate layer as a polymer insulating layer, and upper and lower metal-plated layers as conductive layers. Compared to pure metal current collectors, composite current collectors can reduce weight by 50% to 80%, thereby increasing battery energy density. Currently, the insulating layer is generally made of PET for composite aluminum foil and PP for composite copper foil. Since the intermediate layer is insulating, and the upper and lower metal-plated layers are non-conductive, a portion of the composite foil current collector serves as the electrode. The connection between the electrode and the terminal post is typically achieved using ultrasonic roll welding. This involves rolling a layer of metal foil onto the surfaces of the upper and lower metal-plated layers of the composite foil, and then welding multiple metal electrodes to the terminal post using ultrasonic roll welding.

[0003] In existing technologies, a portion of the composite foil current collector is used as the tab and the tab is connected to the electrode post. The tab is welded using ultrasonic roll welding. However, the metal layer on the composite current collector is relatively thin, typically only 1µm thick. In actual welding, it is easy to melt and burn through, resulting in low welding tensile strength and causing the tab to fall off. Utility Model Content

[0004] In view of this, the present invention provides a tab connection device and a battery pack to solve the problem of tab detachment caused by low welding tensile strength.

[0005] In a first aspect, this utility model provides a tab connection device, comprising: A substrate is foldably formed with a piercing surface and a receiving surface, the piercing surface and the receiving surface being disposed opposite to each other; The puncture section is disposed on the puncture surface; A recessed portion is provided on the receiving surface, and the recessed portion and the puncture portion are provided correspondingly, with the top end of the puncture portion and the bottom end of the recessed portion abutting each other.

[0006] Beneficial effects: A portion of the composite foil current collector is used as an electrode tab. The electrode tab is folded by the substrate and held by the piercing surface and the receiving surface. The electrode tab layer is pierced by the top of the piercing part and abuts against the bottom of the recess. During this process, the pierced composite foil current collector does not disappear, but is squeezed to the side of the piercing part and gathered in the compression space due to the compression of the piercing part. Then, the extruded composite foil current collector is fixed in the recess by ultrasonic welding, which strengthens the welding firmness.

[0007] In one optional embodiment, both the puncture portion and the recessed portion are provided in multiples. The multiple puncture portions are spaced apart along the length direction on the puncture surface and extend along the width direction of the puncture surface; the recessed portions are spaced apart along the length direction on the receiving surface and extend along the width direction of the receiving surface.

[0008] Beneficial effects: Multiple puncture and recess portions are provided, which can provide multiple fixing points when fixing multiple layers of tabs, thereby providing multiple welding points for the tabs. This arrangement is conducive to the firm welding of the tabs.

[0009] In one optional embodiment, the puncture portion and the puncture surface satisfy the following relationship: 0.01N+0.1≤H1≤0.01N+0.4; Wherein, H1 is the distance from the tip of the puncture part to the puncture surface, and N is the number of layers of tabs that can be accommodated between the puncture surface and the receiving surface.

[0010] Beneficial effect: Under the premise that the distance H1 from the top of the puncture part to the puncture surface and the number of tab layers N satisfy this formula, sufficient welding pull force can be obtained after the tab is welded, thus solving the problem of weld detachment.

[0011] In one optional embodiment, the orthographic projection of the puncture portion on the puncture surface is rectangular, and the cross-section of the puncture portion is an isosceles triangle. The recessed portion is a V-shaped groove, which includes a first inclined surface and a second inclined surface arranged opposite to each other, and the opening of the V-shaped groove is located on the receiving surface.

[0012] Beneficial effects: The orthographic projection of the puncture part on the puncture surface is rectangular, and the cross-section of the puncture part is an isosceles triangle. That is to say, the puncture part is a triangular prism structure. One side of the puncture part is attached to the puncture surface. This arrangement can ensure that the puncture part can stably puncture the multi-layered tabs stacked together.

[0013] In one alternative embodiment, the apex angle α of the cross-section of the puncture portion is smaller than the included angle β between the first inclined plane and the second inclined plane.

[0014] Beneficial effects: It facilitates the smooth contact of the tip of the puncture site with the bottom of the recess, thus completing the puncture of the tab.

[0015] In one optional embodiment, the apex angle α of the cross-section of the puncture portion is 30°-45°.

[0016] Beneficial effects: The smaller the angle of the apex of the puncture site, the easier it is for the puncture site to pierce the stacked tab layers, and more efficiently achieve the connection between the multiple tab layers to achieve the effect of drainage.

[0017] In one optional embodiment, the length L of the orthographic projection contour of the puncture part on the puncture surface is 1-3 mm, and a plurality of puncture parts are arranged at equal intervals.

[0018] Beneficial effects: In other words, the bottom side length of the puncture part is 1~3mm, and multiple puncture parts are arranged at equal intervals, with the same spacing between two adjacent puncture parts, which helps to ensure a stable current flow after puncturing the multi-layer tabs in the puncture part.

[0019] In one alternative implementation, The distance H2 between the bottom end of the V-shaped groove and the receiving surface is 0.05-0.1 mm, and the following relationship exists between the V-shaped groove and the puncture portion: W1 > W2. Wherein, W1 is the opening width of the V-shaped groove along the length direction of the receiving surface, and W2 is the width of the orthographic projection of the puncture part onto the receiving surface along the length direction of the receiving surface.

[0020] Beneficial effects: After the substrate is folded, the top of the puncture part and the bottom of the recessed part overlap. The opening width W1 of the V-shaped groove is greater than the width W2 of the orthographic projection of the puncture part on the receiving surface, which helps to reserve space for the extruded material of the punctured tab (composite foil), making it easier for the tab to be ultrasonically welded subsequently.

[0021] In one optional embodiment, the tab connection device further includes an adapter portion, which is fixedly disposed on the substrate and connected to the long side or short side of the puncture surface.

[0022] Beneficial effects: One end of the adapter is connected to the puncture surface, and the other end is connected to the electrode post. The adapter facilitates the electrical connection between the electrode tab and the electrode post.

[0023] Secondly, this utility model also provides a battery pack, including multiple battery cells, each of which is provided with a tab, and also includes the tab connecting device, wherein the tabs on the multiple battery cells are stacked between the puncture portion and the recessed portion.

[0024] Beneficial effects: The multi-layered tabs of the battery cell are directly connected through the tab connection device, which eliminates the need for roll welding and other equipment or process changes. This can significantly shorten the battery cell production time, reduce production costs, and improve production efficiency. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of an electrode connecting device according to an embodiment of the present invention, wherein the adapter part is located on the long side of the puncture surface; Figure 2 This is a cross-sectional view of a tab connecting device according to an embodiment of the present invention, which clamps and pierces multiple tabs. Figure 3 This is a schematic diagram of the structure of an electrode connecting device according to an embodiment of the present invention, wherein the adapter part is located on the short side of the puncture surface.

[0027] Explanation of reference numerals in the attached figures: 1. Substrate; 2. Puncture surface; 21. Puncture portion; 22. Recessed portion; 221. First inclined surface; 222. Second inclined surface; 3. Receiving surface; 4. Extrusion space; 5. Adapter portion; 6. Tab. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0029] In related technologies, due to the insulating middle layer and the fact that the upper and lower metal layers are only about 1μm thick, direct conductivity is not possible. Therefore, an auxiliary metal foil is first welded to the upper and lower surfaces of the composite foil tab using ultrasonic roll welding to achieve electrical connection and thicken the surface. This metal foil is then welded to the electrode post. However, the extremely thin metal plating is easily melted through or torn during roll welding due to process fluctuations, resulting in insufficient weld strength and causing incomplete welds or detachment. The additional roll welding process increases equipment costs, reduces production efficiency, and the added metal foil partially offsets the lightweight advantage of the composite foil. Therefore, there is an urgent need for a device that can directly and reliably connect the tab.

[0030] The following is combined Figures 1 to 3 The following describes embodiments of the present invention.

[0031] Please see Figures 1 to 3Wherein, direction A is the length direction of the puncture surface 2 or the receiving surface 3, and direction B is the width direction of the puncture surface 2 or the receiving surface 3. According to an embodiment of the present invention, one aspect provides an electrode tab connection device, including an integral substrate 1. The substrate 1 is preferably made of a highly conductive metallic material, such as copper, aluminum, or their alloys, with a thickness between 0.1 mm and 0.3 mm, possessing a certain degree of rigidity and foldability. The substrate 1 can be folded in the middle region to form the opposing puncture surface 2 and the receiving surface 3. After folding, the puncture surface 2 and the receiving surface 3 are substantially parallel, together forming the area for clamping the electrode tab 6.

[0032] A puncture portion 21 is integrally formed on the puncture surface 2 by stamping, etching, or precision machining. In this embodiment, the puncture portion 21 is an elongated protrusion extending along the width direction of the puncture surface 2. Specifically, the orthographic projection of the puncture portion 21 on the puncture surface 2 is rectangular, and its cross-section is an isosceles triangle. In other words, the puncture portion 21 is a triangular prism structure, with its base fixed to the puncture surface 2 and its apex α being sharp, for puncturing the tab 6.

[0033] It should also be noted here that the apex angle α is the angle between the triangular prism-shaped puncture part 21 and the puncture surface 2. The puncture part 21 is a triangular prism structure, and its two angles that connect with the puncture surface 2 are the base angles.

[0034] On the receiving surface 3, a recess 22 is provided directly opposite the puncture portion 21. This recess 22 is a V-shaped groove, comprising a first inclined surface 221 and a second inclined surface 222 disposed opposite each other, with the opening of the V-shaped groove located on the receiving surface 3. The apex angle α of the cross-section of the puncture portion 21 is smaller than the included angle β between the first inclined surface 221 and the second inclined surface 222 of the V-shaped groove. This angular relationship ensures that when the substrate 1 is folded, the sharp tip of the puncture portion 21 can smoothly and without interference abut against the bottom end of the V-shaped groove.

[0035] It should also be noted that the apex angle α of the cross-section of the puncture site 21 is 30°-45°.

[0036] Optionally, the value of α is any one of 30°, 31°, 32°, 33°, 34°, 35°, 36°, 37°, 38°, 39°, 40°, 41°, 42°, 43°, 44°, 45° or a value between any two values.

[0037] When the substrate 1 is folded, causing the piercing surface 2 and the receiving surface 3 to clamp the multilayer composite foil tabs 6, the tip of the piercing part 21 will pierce these tab layers 6. The pierced tab layers 6 (composite foil material) do not disappear, but are squeezed out and gathered to both sides of the piercing part 21 and the interior space of the V-shaped groove under the squeezing action of the piercing part 21, thereby forming a squeezing space 4 between the outer wall of the piercing part 21 and the inner wall of the recess 22 (i.e., the first inclined surface 221 and the second inclined surface 222). This squeezing space 4 accommodates the squeezed and deformed tab material 6.

[0038] Subsequently, ultrasonic welding is applied to the entire clamping area. The energy of the ultrasound causes the metal material (from the upper and lower coatings of the composite foil) concentrated in the extrusion space 4 to undergo plastic flow and metallurgical bonding, while potentially causing the polymer material to partially melt or soften and interlock with the metal structure. This mechanical-metallurgical composite connection method greatly enhances the strength of the weld joint and provides a welding tensile strength far exceeding that of traditional roll welding.

[0039] To achieve stable, multi-point connection of the multi-layer tabs 6, multiple puncture portions 21 and recesses 22 are provided. The multiple puncture portions 21 are arranged at equal intervals along the length of the puncture surface 2 and extend along the width direction. Correspondingly, the multiple recesses 22 are also arranged at equal intervals along the length of the receiving surface 3 and are directly opposite the puncture portions 21. This multi-row, elongated puncture-extrusion structure forms multiple strong welding points, ensuring uniform and stable current conduction after welding.

[0040] Furthermore, the height H1 of the puncture section 21 (i.e., the distance from its tip to the puncture surface 2) and the number N of the electrode tabs 6 to be clamped satisfy the following relationship: 0.01N+0.1≤H1≤0.01N+0.4, in millimeters. For example, when clamping 20 layers of electrode tabs 6, H1 should be designed to be between 0.01×20+0.1=0.3mm and 0.01×20+0.4=0.6mm. This formula is derived from a large number of experiments and can ensure that while puncturing a sufficient number of electrode tabs 6, it provides just the right amount of material filling to the compression space 4, thereby obtaining the optimal welding pull force.

[0041] When H1 < 0.01N + 0.1 (i.e., the height of the puncture portion 21 is insufficient), the tip of the puncture portion 21 will not be able to effectively pierce the entire tab layer, or although it can pierce, it will not reliably abut against the bottom of the recess 22. This results in the punctured tab material not being sufficiently compressed and filled into the compression space 4 formed by the outer wall of the puncture portion 21 and the inner wall of the recess 22. Furthermore, in the subsequent ultrasonic welding process, due to the insufficient total amount and sparse distribution of tab material in the compression space 4, continuous and strong weld points cannot be formed. As a result, the welding pull force is far below the safety threshold, and when the battery is subjected to vibration or impact, the tab 6 is very likely to detach from the connection device, causing connection failure.

[0042] When H1 > 0.01N + 0.4 (i.e., the height of the puncture portion 21 is too high), the excessively high puncture portion 21 will pierce the tab with excessive pressure and depth. This can easily cause macroscopic tearing or stretching deformation of the fragile composite foil current collector (especially the metal coating that is only 1μm thick) around the puncture point, thereby weakening the mechanical strength of the tab root and even causing some tabs to be damaged before welding. In extreme cases, excessive puncture force may directly pierce other components inside the battery pack, or cause the puncture portion 21 itself to undergo plastic deformation or even break due to stress concentration, seriously affecting the reliability and service life of the device.

[0043] Therefore, the height H1 of the puncture section 21 and the number N of tabs to be clamped satisfy the relationship 0.01N+0.1≤H1≤0.01N+0.4, precisely defining an optimal design window. This ensures that, for a given number of tab layers N, the puncture section 21 can produce just the right puncture and compression effect: generating sufficient, tightly contacting metal material to form a high-strength weld joint, while avoiding various damages caused by excessive puncture. Any deviation from this formula will fail to simultaneously and optimally resolve the inherent contradiction between "low weld pull" and "avoiding weld burn-through," thus significantly diminishing the core advantages of this embodiment.

[0044] In this embodiment, the length L (i.e. the length of the triangular prism) of the orthographic projection of the puncture part 21 on the puncture surface 2 is 1-3 mm.

[0045] Optionally, the value of L is any one of 1mm, 2mm, 3mm or a value between any two of them.

[0046] It should also be noted that the distance H2 between the bottom of the V-shaped groove and the receiving surface 3 is 0.05-0.10mm, and its opening width W1 is greater than the width W2 of the orthographic projection of the puncture part 21 on the receiving surface 3, so as to ensure that the puncture part 21 can enter smoothly and reserve sufficient space for the extruded material.

[0047] In other words, the V-shaped groove and the puncture portion 21 satisfy the following relationship: W1 > W2. Wherein, W1 is the opening width of the V-shaped groove along the length direction of the receiving surface 3, and W2 is the width of the orthographic projection of the puncture part 21 onto the receiving surface 3 along the length direction of the receiving surface 3.

[0048] Optionally, the value of H2 is any one of 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.10mm or a value between any two of these values.

[0049] Please see Figure 1 and Figure 3 The electrode connecting device further includes an adapter 5. The adapter 5 is fixedly disposed on the substrate 1 and is specifically connected to one long side of the puncture surface 2. The adapter 5 can be a lug integrally formed with the substrate 1 by stamping, or it can be an independent component connected by means of laser welding or other methods.

[0050] The adapter 5 serves as a bridge between the tab connection device and the battery terminals (not shown). After the multi-layer tabs 6 are securely connected to the tab connection device, the adapter 5 can be reliably electrically connected to the battery terminals using methods such as laser welding, ultrasonic welding, or bolt connection. The design of the adapter 5 makes the entire connection process more modular and convenient, improving the assembly efficiency of the battery module.

[0051] According to an embodiment of the present invention, another aspect is provided: a battery pack employing the above-described tab connection device.

[0052] The battery pack includes multiple cells (such as lithium-ion cells), each of which has a tab 6 formed by a composite foil current collector. When assembling the battery pack, the tabs 6 of multiple cells (e.g., 20 to 50 layers) are stacked and aligned, and then placed between the puncture surface 2 and the receiving surface 3 of the tab connection device.

[0053] Next, the substrate 1 is folded so that the puncture surface 2 and the receiving surface 3 come together. During this process, the puncture part 21 punctures all the tab 6 layers and presses against the bottom end of the recess 22, and the tab 6 material is squeezed and filled into the compression space 4.

[0054] Then, an ultrasonic welding machine is used to apply welding pressure and high-frequency vibration to the closed piercing surface 2 and receiving surface 3 areas. The ultrasonic energy causes the metal plating in the compression space 4 to weld, forming a strong connection point.

[0055] Finally, the adapter 5 is welded to the common terminal of the battery pack to complete the parallel or series connection of all the cells.

[0056] In this application, "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0057] The battery mentioned in the embodiments of this application can be a single physical module comprising one or more cells to provide higher voltage and capacity. For example, the battery mentioned in this application can include cells, battery modules, or battery packs.

[0058] A battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. A battery cell can be cylindrical, cuboid, or other shapes, and the embodiments of this application are not limited to this.

[0059] When there are multiple battery cells, they are connected in series, parallel, or mixed via a busbar. In some embodiments, the battery can be a battery module; when there are multiple battery cells, they are arranged and fixed to form a battery module. In some embodiments, the battery can be a battery pack, which includes a housing and battery cells, with the cells or battery modules housed within the housing. In some embodiments, the housing can be part of the vehicle's chassis structure.

[0060] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A tab connection device, characterized in that, include: The substrate (1) is foldably formed with a piercing surface (2) and a receiving surface (3) arranged opposite to each other. The puncture portion (21) protrudes from the puncture surface (2); The recess (22) is recessed in the receiving surface (3) and is directly opposite the position of the puncture part (21); When the substrate (1) is folded, the top end of the puncture part (21) abuts against the bottom end of the recess (22), and a compression space (4) is formed between the outer wall of the puncture part (21) and the inner wall of the recess (22) for compressing and accommodating the tab (6).

2. The electrode connecting device according to claim 1, characterized in that, Both the puncture portion (21) and the recessed portion (22) are provided in multiples. The multiple puncture portions (21) are spaced apart along the length direction on the puncture surface (2) and extend along the width direction of the puncture surface (2). The recessed portions (22) are spaced apart along the length direction on the receiving surface (3) and extend along the width direction of the receiving surface (3).

3. The electrode connecting device according to claim 1, characterized in that, The puncture portion (21) and the puncture surface (2) satisfy the following relationship: 0.01N+0.1≤H1≤0.01N+0.4; Wherein, H1 is the distance from the top of the puncture part (21) to the puncture surface (2), and N is the number of layers between the puncture surface (2) and the receiving surface (3) that can accommodate the tabs (6).

4. The electrode connecting device according to claim 1, characterized in that, The orthographic projection of the puncture part (21) on the puncture surface (2) is a rectangle, and the cross-section of the puncture part (21) is an isosceles triangle. And / or, the recess (22) is a V-shaped groove, the V-shaped groove includes a first inclined surface (221) and a second inclined surface (222) disposed opposite to each other, and the opening of the V-shaped groove is located on the receiving surface (3).

5. The electrode connecting device according to claim 4, characterized in that, The apex angle α of the cross section of the puncture part (21) is smaller than the included angle β between the first inclined surface (221) and the second inclined surface (222).

6. The electrode connecting device according to claim 5, characterized in that, The apex angle α of the cross section of the puncture part (21) is 30°-45°.

7. The electrode connecting device according to claim 4, characterized in that, The orthographic projection contour of the puncture part (21) on the puncture surface (2) has a length L of 1-3 mm along the width direction of the puncture surface (2), and multiple puncture parts (21) are arranged at equal intervals.

8. The electrode connecting device according to claim 4, characterized in that, The distance H2 between the bottom end of the V-shaped groove and the receiving surface (3) is 0.05-0.1 mm, and the V-shaped groove and the puncture part (21) satisfy the following relationship: W1 > W2. Wherein, W1 is the opening width of the V-shaped groove along the length direction of the receiving surface (3), and W2 is the width of the orthographic projection of the puncture part (21) onto the receiving surface (3) along the length direction of the receiving surface (3).

9. The electrode connecting device according to claim 1, characterized in that, The electrode connection device further includes an adapter (5), which is fixedly disposed on the substrate (1) and connected to the long or short side of the puncture surface (2).

10. A battery pack comprising a plurality of battery cells, each of the battery cells having a tab (6), characterized in that, It also includes the tab connection device according to any one of claims 1-9, wherein the tabs on the plurality of said cells are stacked between the puncture portion (21) and the recess portion (22).

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