Welding structure of tab and connecting piece and welding assembly thereof

Abstract

The application relates to the technical field of blade battery, and provides a welding structure of a tab and a connecting sheet and a welding assembly thereof. The welding structure comprises a tab located on one side of the length direction of a pole group and a connecting sheet; the connecting sheet has a tab connecting part and a pole connecting part connected with each other; the tab connecting part comprises first clamping ears and second clamping ears which are arranged at intervals along the thickness direction of the connecting sheet; the first clamping ears and the second clamping ears are both formed by stacking at least one layer of metal foil material; the tab is clamped between the first clamping ears and the second clamping ears, and the three are connected through ultrasonic welding; meanwhile, the thickness of the tab, the thickness and the number of layers of the metal foil material are limited. The welding structure of the tab and the connecting sheet can not only improve the welding strength of the tab and the connecting sheet, the tensile and vibration impact resistance, but also improve the welding yield, so that the production line production yield and efficiency can be improved, the cost loss can be reduced, and the quality and use reliability of the battery cell can be improved.

Description

Technical Field

[0001] This application relates to the field of blade battery technology, and in particular to a welding structure of a tab and a connecting piece and its welding assembly. Background Technology

[0002] With the increasing maturity of lithium-ion battery technology, lithium-ion batteries are widely used as power batteries in electric vehicles and energy storage, and the requirements for the performance and safety of lithium-ion batteries are becoming increasingly stringent.

[0003] Structurally, a blade lithium battery includes a casing, an electrode assembly housed within the casing, and a cover plate. The cover plate is welded to the casing to achieve internal sealing and encapsulate the electrode assembly within the casing. The electrode assembly consists of positive and negative tabs connected to the positive and negative terminals of the cover plate via connecting tabs. The battery cell is charged and discharged by extending positive and negative terminals through the cover plate.

[0004] Currently, the welding process between the tabs and connecting pieces in traditional blade batteries suffers from a high defect rate. This not only reduces the overall production efficiency of the production line but also leads to material scrap and increased cost losses. Furthermore, the welding strength of the tabs and connecting pieces is susceptible to breakage and failure under mechanical impact conditions on the battery pack. Summary of the Invention

[0005] In view of this, this application aims to propose a welding structure for the electrode tab and the connecting piece, so as to improve the welding strength and welding yield.

[0006] To achieve the above objectives, the technical solution of this application is implemented as follows:

[0007] A welding structure for an electrode lug and a connecting piece includes an electrode lug located on one side of the electrode assembly along its length, and a connecting piece.

[0008] The connecting piece has a connected tab connection portion and a pole connection portion. The tab connection portion includes a first clamp and a second clamp that are spaced apart along the thickness direction of the connecting piece. The first clamp and the second clamp are both made of at least one layer of metal foil. The tab is sandwiched between the first clamp and the second clamp, and the tab is connected to the first clamp and the second clamp by ultrasonic welding.

[0009] The thickness t1 of the electrode tab satisfies: 0.2mm≤t1≤2.2mm, the thickness t2 of the metal foil satisfies: 0.05mm≤t2≤0.3mm, and the total number of layers n of the metal foil satisfies: 2≤n≤16.

[0010] Furthermore, the tab connection and the pole connection are formed by stacking metal foil in one piece; the sum of the number of foil layers of the first clip and the second clip is the same as the number of foil layers of the pole connection.

[0011] Furthermore, the thickness t3 of the first clamping ear satisfies: 0.2mm≤t3≤1.5mm, and the thickness t4 of the second clamping ear satisfies: 0.2mm≤t4≤1.5mm.

[0012] Furthermore, a weak structure is provided between the tab connection portion and the pole post connection portion; the weak structure is used to guide the tab connection portion to bend relative to the pole post connection portion.

[0013] Compared with related technologies, this application has the following advantages:

[0014] (1) The welding structure of the electrode and the connecting piece described in this application is achieved by placing the electrode between the first clip and the second clip of the connecting piece, such that the first clip and the second clip are made of stacked metal foil, and the first clip, the electrode and the second clip are welded by ultrasonic welding. This clamping structure can greatly increase the welding joint area, thereby improving the welding strength between the electrode and the connecting piece, and also improving the overall tensile and vibration impact resistance after the electrode and the connecting piece are welded.

[0015] Furthermore, by limiting the thickness of the tabs and the thickness and number of layers of the metal foil, it is possible to avoid damage to the connecting piece during ultrasonic welding of the tabs and connecting pieces due to excessively thin metal foil. On the other hand, it is also possible to prevent insufficient connection strength between the tabs and connecting pieces due to excessively thick metal foil, which would make them difficult to deform during welding. This improves the welding yield and quality of the tabs and connecting pieces, thereby increasing the production yield and efficiency of the production line, reducing cost losses, and improving the quality and reliability of the battery cells.

[0016] (2) The tab connection and the pole connection are formed by stacking metal foil in one piece. On the one hand, it is convenient to process and prepare the connecting piece and improve production efficiency. On the other hand, it can eliminate stress concentration and fracture risk in the transition area between the tab connection and the pole connection, making the overall stiffness and strength of the connecting piece more uniform. It is also convenient to bend the connecting piece in subsequent processes.

[0017] (3) By limiting the thickness of the first and second clamps, each electrode can have sufficient thickness to provide stable clamping force, ensuring that the electrode does not shift or wrinkle during welding. It can also prevent damage to the clamps when the welding head and welding teeth are pressed due to the clamp thickness being too thin, and prevent the electrode from being difficult to deform when pressed with the connecting piece due to the clamp thickness being too thick, resulting in insufficient connection strength between the two.

[0018] (4) By setting a weak structure between the tab connection and the pole connection, the bending of the pole connection relative to the tab connection can be better guided, thereby improving the bending quality of the connecting piece.

[0019] Another objective of this application is to provide a welding assembly for the welding structure of the above-mentioned electrode tab and connecting piece, which includes a support plate for supporting the electrode tab and the connecting piece, and a welding head disposed above the support plate; the welding head is provided with a plurality of welding teeth arranged at intervals, each of the welding teeth being frustum-shaped.

[0020] Furthermore, the dimension H1 of each of the welding teeth in the thickness direction of the connecting piece satisfies: 0.3mm≤H1≤2.5mm, and the dimension H1 of each of the welding teeth in the thickness direction of the connecting piece satisfies: 0.2≤H1 / t1≤0.8 with respect to the thickness t1 of the electrode tab.

[0021] Furthermore, the dimension H1 of each of the welding teeth in the thickness direction of the connecting piece satisfies the following relationship with the thickness t3 of the first clamping ear: 1.1≤H1 / t3≤2.

[0022] Furthermore, the support plate has a protrusion corresponding to the position of the second clamping ear.

[0023] Furthermore, the projection of the protrusion onto the support plate is in the shape of a rhombus, triangle, rectangle, or other polygon.

[0024] Furthermore, the dimension d of the protrusion in the thickness direction of the connecting piece satisfies: 0.05mm≤d≤0.5mm.

[0025] The welding assembly described in this application, through the provision of a support plate and a welding head, enables the support plate to provide better support for the tabs and connecting pieces. The welding head is provided with multiple welding teeth arranged at intervals and in a frustum shape, which can achieve simultaneous action at multiple points. The ultrasonic energy is concentrated at the welding interface, which helps to improve welding efficiency and strength, thereby improving the stability of the performance at the joint between the tabs and connecting pieces. At the same time, it can also improve the welding strength and welding yield of the tabs and connecting pieces, thereby improving the production line yield and efficiency, reducing cost losses, and improving the quality and reliability of the battery cells.

[0026] By limiting the dimensions of each welding tooth in the thickness direction of the connecting piece, and limiting the relationship between them and the thickness of the electrode, a sufficiently deep welding bonding layer can be formed, avoiding insufficient welding strength due to excessive size, and preventing electrode breakage due to excessive pressing.

[0027] By limiting the ratio between the depth of the welding teeth and the thickness of the first clamping lug, we can avoid insufficient welding strength caused by insufficient deformation of the clamping lug due to an excessively small ratio. On the other hand, we can also prevent the clamping lug from being cracked, torn, or having insufficient welding strength due to an excessively large ratio.

[0028] The protrusions on the support plate can increase the coefficient of friction between the second clamping part of the connecting piece and the support plate, thereby effectively preventing the connecting piece from slipping when the electrode tab and the connecting piece are pressed together, and improving the fixing effect between the electrode tab and the second clamping part.

[0029] The projection of the protrusion on the support plate is in the shape of a rhombus, triangle, rectangle or other polygon. Its structure is relatively simple, which makes it easy to prepare and shape the support plate, and it has a good anti-slip effect.

[0030] By limiting the size of the protrusion in the thickness direction of the connecting piece, it is possible to avoid insufficient welding strength between the electrode tab and the second clamping ear due to the size being too small, which would make it easy to separate. It is also possible to prevent the electrode tab from being damaged due to the size being too large, which would make it difficult to press the welding teeth together. Attached Figure Description

[0031] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0032] Figure 1 This is a schematic diagram of the structure of the electrode tab and connecting piece after welding, as described in the embodiment of this application, from a first-view perspective.

[0033] Figure 2 This is a schematic diagram of the structure of the electrode tab and the connecting piece after welding, as described in the embodiment of this application, from a second perspective.

[0034] Figure 3 for Figure 2 Enlarged view of section A in the middle;

[0035] Figure 4 This is a schematic diagram of the connecting piece described in an embodiment of this application;

[0036] Figure 5 for Figure 4 Enlarged view of section B;

[0037] Figure 6 This is a schematic diagram of the structure of the electrode tab and connecting piece in the engagement state with the welding assembly as described in the embodiments of this application;

[0038] Figure 7 This is a schematic diagram of the welding tooth structure described in the embodiment of this application;

[0039] Figure 8This is a first-view structural schematic diagram of the carrier plate described in an embodiment of this application;

[0040] Figure 9 This is a second-view structural schematic diagram of the carrier plate described in an embodiment of this application;

[0041] Explanation of reference numerals in the attached figures:

[0042] 1. Electrode group; 10. Electrode ear;

[0043] 20. Connecting piece; 200. Metal foil; 201. Electrode connecting part; 202. Electrode connecting part; 203. Weak structure; 2011. First clamping ear; 2012. Second clamping ear;

[0044] 30. Solder mark;

[0045] 3. Welding head; 301 welding teeth;

[0046] 4. Support plate; 401. Protrusion. Detailed Implementation

[0047] To make the technical solution and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0048] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0049] Furthermore, it should be noted that in the description of this application, if terms such as "upper," "lower," "inner," or "outer" appear, indicating orientation or positional relationship, these are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, if terms such as "first" or "second" appear, they are also used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] Furthermore, in the description of this application, unless otherwise expressly defined, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application in light of the specific circumstances.

[0051] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0052] The present application will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0053] An embodiment of the first aspect of this application provides a welding structure for a tab and a connecting piece, which can improve the welding strength and welding yield of the tab and the connecting piece.

[0054] In related technologies, the blade lithium battery structurally includes a casing, an electrode assembly housed within the casing, and a cover plate. The cover plate is welded to the casing to achieve internal sealing and encapsulate the electrode assembly within the casing. The electrode assembly consists of positive and negative tabs connected to the positive and negative terminals of the cover plate via connecting tabs. The battery cell is charged and discharged by extending positive and negative terminals through the cover plate.

[0055] Currently, the welding process between the tabs and connecting pieces in traditional blade batteries suffers from a high defect rate. This not only reduces the overall production efficiency of the production line but also leads to material scrap and increased cost losses. Furthermore, the welding strength of the tabs and connecting pieces is susceptible to breakage and failure under mechanical impact conditions on the battery pack.

[0056] In view of this, in order to overcome the shortcomings of related technologies, in the welding structure of the electrode tab and the connecting piece in this embodiment, combined with Figures 1 to 9 As shown, the overall design includes a tab 10 located on one side of the pole group 1 along its length, and a connecting piece 20.

[0057] The connecting piece 20 has a connected tab connecting portion 201 and a pole connecting portion 202. The tab connecting portion 201 includes a first clamp 2011 and a second clamp 2012 spaced apart along the thickness direction of the connecting piece 20. The first clamp 2011 and the second clamp 2012 are both made of at least one layer of metal foil 200 stacked together. The tab 10 is sandwiched between the first clamp 2011 and the second clamp 2012, and the tab 10 is connected to the first clamp 2011 and the second clamp 2012 by ultrasonic welding.

[0058] Furthermore, the thickness t1 of the tab satisfies: 0.2mm≤t1≤2.2mm, the thickness t2 of the metal foil 200 satisfies: 0.05mm≤t2≤0.3mm, and the total number of layers n of the metal foil 200 satisfies: 2≤n≤16.

[0059] At this time, in the above structure, by clamping the electrode 10 between the first clamp 2011 and the second clamp 2012 of the connecting piece 20, the first clamp 2011 and the second clamp 2012 are made of stacked metal foil 200, and the first clamp 2011, the electrode 10 and the second clamp 2012 are ultrasonically welded. This clamping structure can greatly increase the welding joint area, thereby improving the welding strength between the electrode 10 and the connecting piece 20, and also improving the overall tensile and vibration impact resistance after the electrode 10 and the connecting piece 20 are welded.

[0060] Furthermore, by limiting the thickness of the tab 10 and the thickness and number of layers of the metal foil 200, it is possible to prevent damage to the connecting piece 20 during ultrasonic welding of the tab 10 and the connecting piece 20 due to the metal foil 200 being too thin, causing damage to the connecting piece 20 during the pressing process by the welding teeth 301 of the welding head 3. On the other hand, it also prevents insufficient connection strength between the tab 10 and the connecting piece 20 due to the metal foil 200 being too thick, which would make it difficult for the tab 10 and the connecting piece 20 to deform during the pressing process. This improves the welding yield and quality of the tab 10 and the connecting piece 20, thereby increasing the production yield and efficiency of the production line, reducing cost losses, and improving the quality and reliability of the battery cell.

[0061] Based on the above overview, specifically, firstly, it should be noted that the welding structure between the tab 10 and the connecting piece 20 described above is applicable to the structure of a blade battery. Combined with... Figures 1 to 5 As shown, in the blade battery structure, the electrode group 1 has tabs 10 on both sides along its length, which are the positive tab and the negative tab, respectively. To ensure a reliable connection between the tabs 10 of the electrode group 1 and the terminals on the cover plate, a connecting piece 20 is required to transfer the tabs 10 of the electrode group 1 to the terminals on the cover plate.

[0062] In this embodiment, the welding structure between the tab 10 on one side of the length direction of the electrode group 1 and the connecting piece 20 can be either a positive tab and a connecting piece 20 or a negative tab and a connecting piece 20.

[0063] In addition, in this embodiment, the thickness t1 of the tab 10 is between 0.2mm and 2.2mm. Specifically, the thickness t1 of the tab can be set to, for example, 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, or 2.2mm. The thickness t2 of the metal foil 200 is between 0.05mm and 0.3mm. Specifically, the thickness of the metal foil 200 can be set to, for example, 0.5mm, 0.7mm, 1.0mm, 1.2mm, 1.5mm, 1.7mm, 2.0mm, 2.2mm, 2.5mm, 2.7mm, or 3.0mm.

[0064] The total number of layers n of the metal foil 200 is between 2 and 16. In specific implementations, the total number of layers n can be set to, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10; 11; 12, 13, 14, 15, or 16, etc. It should be noted that the number of layers of the metal foil 200 in the first clamp 2011 and the number of layers of the metal foil 200 in the second clamp 2012 can be the same or different. Furthermore, it should be noted that the difference in the number of layers between the two should be as small as possible; for example, the difference in the number of layers should not exceed 3. This can further ensure the welding yield and welding strength between the electrode 10 and the connecting piece 20.

[0065] Continue to combine Figures 1 to 5 As shown, in some exemplary embodiments, for example, the tab connection 201 and the pole connection 202 are formed by stacking integral metal foil 200, in which case the sum of the number of foil layers of the first clip 2011 and the number of foil layers of the second clip 2012 is the same as the number of foil layers of the pole connection 202.

[0066] In the above embodiment, the tab connection 201 and the pole connection 202 are formed by stacking an integral metal foil 200, which not only facilitates the processing and preparation of the connecting piece 20 and improves production efficiency, but also eliminates stress concentration and fracture risk in the transition area between the tab connection 201 and the pole connection 202, making the overall rigidity and strength of the connecting piece 20 more uniform, and also facilitates the bending of the connecting piece 20 in subsequent processes.

[0067] It is worth noting that, in addition to the tab connection 201 and the pole connection 202 being formed by stacking integral metal foil 200, the above-mentioned connection can also be formed by stacking metal foil 200 in a way that includes part of the metal foil 200 of the pole connection 202, while part of it uses a smaller metal foil 200. The connecting piece structure formed by stacking in this way is also possible. In this case, the number of foil layers in the pole connection 202 is greater than the number of foil layers in the tab connection 201.

[0068] Reference Figure 4 As shown, in some of the exemplary embodiments, for example, the thickness t3 of the first clip 2011 satisfies: 0.2mm≤t3≤1.5mm, and the thickness t4 of the second clip 2012 satisfies: 0.2mm≤t4≤1.5mm.

[0069] In specific implementation, the thickness t3 of the first clamping ear 2011 can be set to, for example, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1.0mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, or 1.5mm, etc.

[0070] The thickness t4 of the first clamping ear 2011 can be set to, for example, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1.0mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, or 1.5mm, etc.

[0071] It is worth mentioning that the thickness t3 of the first clip 2011 and the thickness t4 of the second clip 2012 can be the same or different, and as a preferred embodiment, the thickness t3 of the first clip 2011 and the thickness t4 of the second clip 2012 are the same.

[0072] In the above implementation, by limiting the thickness of the first clamping ear 2011 and the second clamping ear 2012, each electrode ear 10 can have sufficient thickness to provide stable clamping force, ensuring that the electrode ear 10 does not shift or wrinkle during the welding process. It can also prevent damage to the clamping ear 10 when the welding head 3 is pressed due to the clamping ear being too thin, and prevent insufficient connection strength between the electrode ear and the connecting piece 20 when the clamping ear is too thick and it is not easy to deform.

[0073] Additionally, refer to Figures 1 to 3As shown, in some exemplary embodiments, for example, a weak structure 203 is provided between the tab connection 201 and the pole connection 202. This weak structure 203 guides the bending of the pole connection 202 relative to the tab connection 201. By providing the weak structure 203 between the tab connection 201 and the pole connection 202, the bending of the pole connection 202 relative to the tab connection 201 can be better guided, improving the bending quality of the connecting piece 20.

[0074] Specifically, as an example structure, such as Figure 1 As shown, the aforementioned weak structure 203 includes, for example, an elongated hole that extends through the thickness of the connecting piece 20, the elongated hole extending in the direction of the bending crease M, and a plurality of elongated holes arranged at intervals along the direction of the bending crease M.

[0075] It is understandable that, in addition to using multiple elongated holes arranged at intervals, the weak structure 203 can also use multiple round holes arranged at intervals, or multiple rectangular holes arranged at intervals. Such a configuration is also acceptable.

[0076] Furthermore, the weld marks 30 formed on the first clamp 2011, the electrode tab 10, and the second clamp 2012, along the length direction of the electrode assembly 1, have a distance a1 between the weld mark 30 and the side of the connecting piece 20 near the root of the electrode tab 10, satisfying the condition: 0.1mm ≤ a1 ≤ 10mm. By limiting the distance a1, not only can the reliability of the welding between the first clamp 2011, the electrode tab 10, and the second clamp 2012 be guaranteed, but also space waste caused by excessive size can be prevented. In specific implementations, the distance a2 can be set to, for example, 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm.

[0077] The distance a2 between the solder mark 30 and the root of the tab 10 satisfies: 0.5mm ≤ a2 ≤ 20mm. This setting effectively avoids damage to the diaphragm caused by excessively small dimensions during the welding process due to high temperatures, and also prevents wasted space due to excessively large dimensions. In specific implementations, the distance a2 can be set to, for example, 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, or 20mm, etc.

[0078] The welding structure of the tab 10 and the connecting piece 20 in this embodiment can not only improve the welding strength of the tab 10 and the connecting piece 20 and improve the tensile and vibration impact resistance, but also improve the welding yield, thereby improving the production yield and efficiency of the production line, reducing cost losses, and improving the quality and reliability of the battery cell.

[0079] An embodiment of the second aspect of this application provides a welding assembly applied to the welding structure of the above-described electrode tab and connecting piece 20, combined with... Figures 6 to 9 As shown, the welding assembly includes a support plate 4 for supporting the electrode tabs and connecting pieces 20, and a welding head 3 disposed above the support plate 4. The welding head 3 is provided with a plurality of welding teeth 301 arranged at intervals, each welding tooth 301 being frustum-shaped.

[0080] Here, the support plate 4 provides good support for the electrode tab 10 and the connecting piece 20. The welding head 3 is provided with multiple welding teeth 301 arranged at intervals and in a frustum shape, which can achieve multi-point simultaneous action during ultrasonic welding, so that the ultrasonic energy is concentrated at the welding interface, which helps to improve welding efficiency and strength, thereby improving the stability of the joint between the electrode tab 10 and the connecting piece 20.

[0081] At the same time, based on the welding structure of the tab 10 and the connecting piece 20, the welding operation of the above-mentioned welding components can also improve the welding strength and welding yield of the tab 10 and the connecting piece 20, thereby improving the production yield and efficiency of the production line, reducing cost losses, and improving the quality and reliability of the battery cell.

[0082] Reference Figure 6 As shown, in some exemplary embodiments, for example, the dimension H1 of each welding tooth 301 in the thickness direction of the connecting piece 20 satisfies: 0.3mm≤H1≤2.5mm, and the dimension H1 of each welding tooth 301 in the thickness direction of the connecting piece 20 satisfies the relationship between the thickness t1 of the tab 10 and the dimension H1 of each welding tooth 301 in the thickness direction of the connecting piece 20: 0.2≤H1 / t1≤0.8.

[0083] In specific implementation, the dimension H1 of each welding tooth 301 in the thickness direction of the connecting piece 20, that is, the depth of each welding tooth 301, can be set to, for example, 0.3mm, 0.5mm, 1.0mm, 1.5mm, 2.0mm, or 2.5mm. The ratio H1 / t1 between the depth H1 of each welding tooth 301 and the thickness t1 of the tab 10 can be set to, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8.

[0084] In the above implementation, by limiting the size of each welding tooth 301 in the thickness direction of the connecting piece 20, and limiting the relationship between it and the thickness of the tab 10, a sufficiently deep welding bonding layer can be formed, avoiding insufficient welding strength due to excessive size, and preventing the tab 10 from breaking or being damaged due to excessive pressing.

[0085] In some exemplary embodiments, for example, the dimension H1 of each welding tooth 301 in the thickness direction of the connecting piece 20 satisfies the following relationship with the thickness t3 of the first clamping ear 2011: 1.1 ≤ H1 / t3 ≤ 2. In specific implementations, the value of H1 / t3 can be set to, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2, etc.

[0086] At this time, by limiting the ratio between the depth of the welding tooth 301 and the thickness of the first clamping ear 2011, on the one hand, it can avoid the electrode ear 10 being pressed in too little due to the ratio being too small, resulting in insufficient welding strength; on the other hand, it can also prevent the clamping ear from being cracked, torn or having insufficient welding strength due to the ratio being too large.

[0087] Combination Figures 5 to 9 As shown, in some exemplary embodiments, for example, a plurality of protrusions 401 are provided on the support plate 4 at intervals corresponding to the second clamp 2012. The provision of these protrusions 401 can increase the coefficient of friction between the second clamp 2012 portion of the connecting piece 20 and the support plate 4, thereby effectively preventing the connecting piece 20 from sliding when the electrode 10 and the connecting piece 20 are pressed together, and improving the fixing effect between the electrode 10 and the second clamp 2012 portion.

[0088] In practice, the projection of the aforementioned protrusion 401 onto the support plate 4 can be, for example, a rhombus, triangle, rectangle, or other polygon. These structural forms are relatively simple, facilitate the fabrication and molding of the support plate 4, and have a good anti-slip effect.

[0089] Combination Figure 8 As shown, for example, the dimension d of the protrusion 401 in the thickness direction of the connecting piece 20 satisfies: 0.05mm ≤ d ≤ 0.5mm. In specific implementations, the dimension d can be set to, for example, 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, or 0.5mm, etc.

[0090] In the above implementation, by limiting the size of the protrusion 401 in the thickness direction of the connecting piece 20, it is possible not only to avoid insufficient welding strength and easy separation between the electrode tab 10 and the second clamping ear 2012 due to the size being too small, but also to prevent the welding teeth 301 from being difficult to press due to the size being too large, thereby causing damage to the electrode tab 10.

[0091] The following tests were conducted on different values ​​of t1, t3, and H1, as well as under the conditions of H1 / t1 = 0.2-0.8 and 1.1 ≤ H1 / t3 ≤ 2. Through multiple embodiments and comparative examples, the welding strength between the tab 10 and the connecting piece 20 under these conditions was verified. The test results are shown in Table 1 below:

[0092] Table 1

[0093]

[0094] Referring to Table 1 above, in Examples 1 to 5, the thickness t1 of the tab 10 satisfies: 0.2mm ≤ t1 ≤ 2.2mm, the thickness t3 of the first clamp 2011 satisfies: 0.2mm ≤ t3 ≤ 1.5mm, and the depth H1 of the welding tooth 301 satisfies: 0.3mm ≤ H1 ≤ 2.5mm. Furthermore, the relationship between the depth H1 of the welding tooth 301 and the thickness t1 of the tab 10 satisfies: 0.2 ≤ H1 / t1 ≤ 0.8, and the relationship between the depth H1 of the welding tooth 301 and the thickness t3 of the first clamp 2011 satisfies: 1.1 ≤ H1 / t3 ≤ 2. Therefore, when the battery cell prepared in this way undergoes vibration and shock testing, the welding between the tab 10 and the clamp of the connecting piece 20 is reliable and meets the strength requirements.

[0095] In Comparative Examples 1 to 4, the value of H1 / t3 in Comparative Example 1 exceeds the lower limit of the ratio limit range, the value of H1 / t3 in Comparative Example 2 exceeds the upper limit of the ratio limit range, the value of H1 / t1 in Comparative Example 3 exceeds the lower limit of the ratio limit range, and the value of H1 / t1 in Comparative Example 4 exceeds the upper limit of the ratio limit range. When the battery cell was subjected to vibration and shock tests, Comparative Examples 1 to 4 all had problems with the tab 10 and the clamping ear separating, and the welding strength between the tab 10 and the connecting piece 20 was insufficient, so they were all unqualified.

[0096] The welding assembly of this embodiment, by welding the above-mentioned electrode 10 and connecting piece 20 welding structure, can not only improve the welding strength of electrode 10 and connecting piece 20, and improve tensile and vibration impact resistance, but also improve the welding yield, thereby improving the production line yield and efficiency, reducing cost losses, and improving the quality and reliability of the battery cell.

[0097] The above descriptions are merely some embodiments of this application and are not intended to limit this application. The technical features or structures in the foregoing different embodiments can be arbitrarily combined to form other specific technical solutions as needed. For those skilled in the art, this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of the claims of this application.

Claims

1. A welding structure for an electrode lug and a connecting piece, characterized in that: This includes the electrode lug located on one side of the electrode assembly along its length, and the connecting piece; The connecting piece has a connected tab connection portion and a pole connection portion. The tab connection portion includes a first clamp and a second clamp that are spaced apart along the thickness direction of the connecting piece. The first clamp and the second clamp are both made of at least one layer of metal foil. The tab is sandwiched between the first clamp and the second clamp, and the tab is connected to the first clamp and the second clamp by ultrasonic welding. The thickness t1 of the electrode tab satisfies: 0.2mm≤t1≤2.2mm, the thickness t2 of the metal foil satisfies: 0.05mm≤t2≤0.3mm, and the total number of layers n of the metal foil satisfies: 2≤n≤16.

2. The welding structure of the electrode lug and the connecting piece according to claim 1, characterized in that: The tab connection and the pole connection are formed by stacking an integral metal foil. The sum of the number of foil layers in the first clip and the second clip is the same as the number of foil layers in the pole connection.

3. The welding structure of the electrode lug and the connecting piece according to claim 2, characterized in that: The thickness t3 of the first clamping ear satisfies: 0.2mm≤t3≤1.5mm, and the thickness t4 of the second clamping ear satisfies: 0.2mm≤t4≤1.5mm.

4. The welding structure of the electrode lug and the connecting piece according to any one of claims 1 to 3, characterized in that: A weak structure is provided between the electrode tab connection part and the electrode post connection part; The weak structure is used to guide the bending of the pole post connection relative to the tab connection.

5. A welding assembly applied to the welding structure of the electrode tab and connecting piece as described in claim 4, characterized in that: Includes a support plate for supporting the electrode tab and the connecting piece, and a welding head disposed above the support plate; The welding head is provided with a plurality of welding teeth arranged at intervals, and each welding tooth is shaped like a frustum.

6. The welding assembly according to claim 5, characterized in that: The dimension H1 of each of the welding teeth in the thickness direction of the connecting piece satisfies: 0.3mm≤H1≤2.5mm, and the dimension H1 of each of the welding teeth in the thickness direction of the connecting piece satisfies: 0.2≤H1 / t1≤0.8 with respect to the thickness t1 of the electrode tab.

7. The welding assembly according to claim 5, characterized in that: The dimension H1 of each of the welding teeth in the thickness direction of the connecting piece satisfies the following relationship with the thickness t3 of the first clamping ear: 1.1≤H1 / t3≤2.

8. The welding assembly according to any one of claims 5 to 7, characterized in that: The support plate has a protrusion at the position corresponding to the second clamping ear.

9. The welding assembly according to claim 8, characterized in that: The projection of the protrusion on the support plate is a rhombus, triangle, rectangle or other polygon.

10. The welding assembly according to claim 8, characterized in that: The dimension d of the protrusion in the thickness direction of the connecting piece satisfies: 0.05mm≤d≤0.5mm.

Images