Welding method of multi-layer tabs and cover plate, battery assembly and battery

Abstract

The invention discloses a welding method of a multi-layer tab and a cover plate, a battery assembly and a battery, and the method comprises the following steps: carrying out ultrasonic pre-welding on a tab on a pole core to form an ultrasonic welding mark; stacking and pairing the pole cores subjected to ultrasonic pre-welding, and stacking and assembling the ultrasonic welding marks and the cover plate adapter sheets in space to form welding positions; the periphery of the welding position is pressed; and the edge of the ultrasonic welding mark and the cover plate adapter plate are welded together through laser, and a lap joint is formed. According to the method, ultrasonic welding can work in the most suitable power interval through multiple times of ultrasonic pre-welding, so that the problem that when the number of layers of the tabs exceeds 100, the tabs are prone to wrinkling and cracking during ultrasonic welding can be solved, and then the overall welding quality can be improved. Besides, the edge of the tab is welded by laser to form a lap joint welding head, so that the input path of heat can be changed, and the insulation performance of the plastic structural part can be prevented from becoming poor. And a plurality of pole cores are stacked and welded, so that the number of pole lug layers of a single battery can reach 400.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a welding method for a multi-layer pole ear and a cover plate, a battery assembly and a battery. Background Art

[0002] In the battery manufacturing process, the welding of multi-layer tabs and cover plates is a crucial process, which is directly related to the connection strength, current capacity and overall performance of the battery. This welding process not only affects the stability of the internal structure of the battery, but also plays a decisive role in its long-term safety and reliability. The traditional welding process is usually divided into two steps: first, the foil tabs are pre-welded using ultrasonic welding technology to connect the originally loose foil into one, laying the foundation for subsequent welding; then, laser welding technology is used to penetrate the tabs and firmly weld them to the cover plate.

[0003] However, with the continuous advancement of battery technology and the iterative upgrade of battery cell design, the thickness of the battery monopolar core has gradually increased, and the number of tab layers has also increased. The number of tab layers of some high-end battery products has exceeded 100. This change has brought unprecedented challenges to the welding process.

[0004] In the ultrasonic welding process, when the number of tab layers exceeds 100, the required welding power often exceeds 80% of the rated power of the equipment, resulting in an increase in the welding amplitude and a significant decrease in the stability of the welding quality. Specifically, the surface tabs are prone to wrinkling and cracking, and weld print delamination problems occur frequently. Since ultrasonic welding technology has reached its capacity limit, for tabs with more than 100 layers, traditional ultrasonic welding methods can no longer meet the needs of battery design, and the reliability of welding quality cannot be guaranteed.

[0005] In the laser welding process, as the number of tab layers increases, the power required for the laser to penetrate the tabs also increases. Currently, it is impossible to weld more than 160 tabs at a time. This not only increases the heat input during the welding process, but also makes the cover plate, especially the plastic structural parts therein, more susceptible to deformation due to high temperatures. The deformation of plastic structural parts will not only affect their original mechanical properties, but more importantly, it will cause the insulation performance to deteriorate, which may cause safety hazards during the use of the battery. Summary of the invention

[0006] The purpose of the present invention is to provide a method for welding a multi-layer tab and a cover plate, a battery assembly and a battery, aiming to solve the problems of poor welding quality of existing ultrasonic welding when the tab has more than 100 layers, and poor insulation performance of plastic structural parts caused by laser welding.

[0007] An embodiment of the present invention provides a method for welding a multi-layer electrode tab and a cover plate, comprising:

[0008] Ultrasonic pre-welding is performed on each pole lug on the pole core to form an ultrasonic weld mark;

[0009] Stacking and pairing the plurality of ultrasonically pre-welded pole cores, and stacking and assembling the plurality of ultrasonic weld marks and cover plate adapter sheets in space to form a welding position;

[0010] Using an upper pressing tool to press the periphery of the welding position;

[0011] The edges of the plurality of ultrasonic weld marks are welded together with the cover plate transfer sheet using a laser to form a lap joint.

[0012] Furthermore, the pole ears of the pole core include: a positive pole ear and a negative pole ear, the positive pole ear is an aluminum alloy ear, and the thickness of the positive pole ear is 8-30um; the negative pole ear is a copper alloy ear, and the thickness of the negative pole ear is 3-20um.

[0013] Furthermore, the cover plate adapter plate includes a positive electrode adapter plate or a negative electrode adapter plate, the material of the positive electrode adapter plate is aluminum alloy, and the thickness of the positive electrode adapter plate is 0.5-3mm; the material of the negative electrode adapter plate is pure copper alloy, and the thickness of the negative electrode adapter plate is 0.5-3mm.

[0014] Furthermore, the number of layers of the pole lugs on the pole core is 20-100.

[0015] Furthermore, before stacking and pairing the plurality of ultrasonically pre-welded pole cores, the method includes:

[0016] The central positioning principle is used to position the plurality of pole cores after ultrasonic pre-welding.

[0017] Furthermore, the stacking manner of the plurality of ultrasonic weld marks is as follows: the edge of the ultrasonic weld mark of the upper layer of the pole core is retracted inward by 0-1.5 mm toward the pole core compared to the edge of the ultrasonic weld mark of the lower layer of the pole core.

[0018] Furthermore, the use of an upper pressing tool to press the periphery of the welding position includes: pressing the periphery of the welding position by a single-side pressing method or a three-side pressing method, and the distance between the edge of the upper pressing tool and the edge of the welding position is 0.5-2mm.

[0019] Furthermore, the method of using a laser to weld the edges of the plurality of ultrasonic welds to the cover plate adapter plate to form a lap joint comprises: stacking the plurality of ultrasonic welds to form a step surface, and the welding width of the laser covers the step surface.

[0020] An embodiment of the present invention further provides a battery assembly, comprising: a cover plate and a plurality of pole cores, wherein the pole cores are provided with pole tabs, and the cover plate and the pole tabs on the plurality of pole cores are welded using the above-mentioned welding method.

[0021] An embodiment of the present invention further provides a battery, comprising: the above-mentioned battery assembly.

[0022] The present invention discloses a method for welding a multi-layer pole ear and a cover plate, a battery assembly and a battery, the method comprising: ultrasonically pre-welding the pole ear on each pole core to form an ultrasonic weld mark; stacking and pairing the pole cores after multiple ultrasonic pre-welding, and stacking and assembling the multiple ultrasonic weld marks and the cover plate adapter in space to form a welding position; using an upper pressing tool to press the surrounding of the welding position; using a laser to weld the edges of the multiple ultrasonic weld marks to the cover plate adapter together to form a lap joint. The present invention enables ultrasonic welding to work in the most suitable power range through multiple ultrasonic pre-welding, thereby avoiding the problem of pole ear wrinkles and cracks when the pole ear exceeds 100 layers, thereby improving the overall welding quality. In addition, by using laser to weld the edge of the pole ear to form a lap weld joint, the heat input path can be changed, thereby avoiding the deterioration of the insulation performance of the plastic structural member. At the same time, by stacking and welding multiple pole cores, the number of pole ear layers of a single battery can reach 400 layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0024] Figure 1 It is a schematic diagram of a process for welding a multi-layer tab and a cover plate;

[0025] Figure 2 It is a schematic diagram of the structure of the pole core after ultrasonic pre-welding;

[0026] Figure 3 for Figure 2 A partial map of

[0027] Figure 4 is a schematic diagram of the structure of a battery assembly;

[0028] Figure 5 A schematic diagram of the structure of a battery assembly when the tabs are misaligned and not cut;

[0029] Figure 6 A schematic diagram of the structure of a battery assembly when the tabs are staggered and cut;

[0030] Figure 7 A schematic diagram of the structure of a battery assembly when the tabs are aligned and not cut;

[0031] Figure 8 A schematic diagram of the structure of a battery assembly when the tabs are aligned and cut;

[0032] Fig. 9 for Figure 4 A partial map of

[0033] Description of the markings in the figure:

[0034] 1. Pole core; 2. Pole ear; 3. Cover plate adapter; 4. Ultrasonic welding mark; 5. Pole ear tower-shaped thinning area; 6. Lap joint. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0037] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0038] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0039] See also Figure 1-4 This embodiment provides a method for welding a multi-layer tab and a cover plate, comprising:

[0040] S101: ultrasonically pre-weld the pole lugs on each pole core to form an ultrasonic weld mark;

[0041] S102: stacking and pairing the plurality of ultrasonically pre-welded pole cores, and stacking and assembling the plurality of ultrasonic weld marks and cover plate adapter sheets in space to form a welding position;

[0042] S103: Using an upper pressing tool to press the periphery of the welding position;

[0043] S104: using a laser to weld the edges of the plurality of ultrasonic weld marks to the cover plate adapter sheet to form a lap joint.

[0044] This embodiment uses multiple ultrasonic pre-welding to enable ultrasonic welding to work in the most suitable power range, thereby avoiding the problem of tab wrinkles and cracks when the tab has more than 100 layers, thereby improving the overall welding quality. In addition, by using laser welding on the edge of the tab to form a lap weld, the heat input path can be changed, thereby avoiding the deterioration of the insulation performance of the plastic structural part.

[0045] In this embodiment, the pole lugs 2 of the pole core 1 include: a positive pole lug and a negative pole lug. The positive pole lug is an aluminum alloy lug with a thickness of 8-30 um; the negative pole lug is a copper alloy lug with a thickness of 3-20 um.

[0046] The use of aluminum alloy for the positive electrode tab can effectively reduce the internal resistance of the battery and improve the energy conversion efficiency of the battery. The thickness of the positive electrode tab is 8-30um, which can effectively balance the conductivity and mechanical strength of the tab, ensuring its stability and reliability during long-term use. The use of copper alloy for the negative electrode tab can ensure that the negative electrode tab operates stably under high current density and reduce energy loss. The thickness of the negative electrode tab is 3-20um, which also takes into account the balance between conductivity and mechanical strength. The thinner tab thickness helps to reduce the internal resistance of the battery and improve the charging and discharging efficiency. At the same time, the tab within this thickness range also has good flexibility and adaptability, and can adapt to the deformation that may occur in the battery during charging and discharging.

[0047] In this embodiment, the cover plate adapter plate 3 can have two different forms: the first is integrated with the cover plate, and this design integrates the adapter plate directly into the cover plate, making the entire assembly more compact and efficient.

[0048] Another form is a separate metal sheet. In this design, the adapter is an independent component, one end of the adapter is connected to the pole ear 2, and the other end of the adapter is connected to the cover plate pole. This design provides greater flexibility and adaptability because the adapter can be designed and adjusted according to specific needs without affecting the overall structure of the cover.

[0049] It should be noted that, regardless of the structural form, the pole lug 2 and the cover plate implemented by the method of the present invention are within the protection scope of the present invention.

[0050] In this embodiment, the cover plate adapter plate 3 includes a positive electrode adapter plate or a negative electrode adapter plate. The material of the positive electrode adapter plate is aluminum alloy, and the thickness of the positive electrode adapter plate is 0.5-3mm; the material of the negative electrode adapter plate is pure copper alloy, and the thickness of the negative electrode adapter plate is 0.5-3mm.

[0051] In order to meet the normal welding connection requirements and electrical conductivity requirements, the cover plate adapter 3 is made of the same material as the corresponding same-pole tab 2. For example, if it is used for welding the positive pole tab, the positive pole tab is an aluminum alloy tab, and the corresponding cover plate adapter 3 is also made of aluminum alloy. If it is used for welding the negative pole tab, the negative pole tab is a copper alloy tab, and the corresponding cover plate adapter 3 is also made of pure copper alloy. The thickness of 0.5-3mm can ensure good thermal conductivity, help battery temperature management, and improve safety.

[0052] In this embodiment, please refer to Figure 2 and Figure 3 , ultrasonic pre-welding the pole ear 2 on each pole core 1 to form an ultrasonic weld mark 4 includes: using an ultrasonic welding machine to pre-weld the pole ear 2 on each pole core 1 respectively, pre-welding the pole ear 2 on each pole core 1 together, and forming a flat ultrasonic weld mark 4.

[0053] The number of layers of the pole lugs 2 on the pole core 1 is 20-100. This ensures that the ultrasonic pre-welding always works under the optimal working conditions, thereby preventing welding defects such as wrinkling and delamination, and improving the welding quality and the battery quality.

[0054] It should be noted that, after the pole ear 2 on the pole core 1 of this embodiment is ultrasonically pre-welded, the pole ear tower-shaped thinned area 5 (such as Figure 3 As shown), or no cutting is required, for example Figure 5 This is a schematic diagram of the tab being misaligned and not cut. Figure 6 This is a schematic diagram of the tab being misaligned and cut; Figure 7 This is a schematic diagram of the tabs being aligned and not cut. Figure 8 The schematic diagram of the alignment and cutting of the tabs is shown in FIG. Among them, cutting or not cutting does not affect the implementation of subsequent laser welding.

[0055] In this embodiment, before stacking and pairing the plurality of ultrasonically pre-welded pole cores 1 , the method includes: positioning the plurality of ultrasonically pre-welded pole cores 1 using a center positioning principle.

[0056] Specifically, the center position of the pole core 1 is found by taking photos or positioning with a fixture, and this position is used as a reference for assembly positioning. After the assembly is completed, the ultrasonic weld marks of the plurality of pole cores 1 are stacked in 4 positions according to the design requirements.

[0057] Using the center positioning principle to position multiple ultrasonically pre-welded pole cores 1 can ensure that the center position of each pole core 1 is accurately aligned to avoid structural deviation and performance degradation.

[0058] Wherein, multiple pole cores 1 are stacked and matched to form a large pole core. According to the battery design requirements, 2 to 4 pole cores 1 can be stacked and matched to form a large pole core (such as Figure 4 As shown in FIG. 1 ). The number of the pole tabs 2 of the assembled large pole core can reach 400 layers. Thus, welding of more than 100 layers of pole tabs 2 can be achieved.

[0059] In this embodiment, the stacking manner of the plurality of ultrasonic weld marks 4 is as follows: the edge of the ultrasonic weld mark 4 of the upper pole core 1 is retracted inwards by 0-1.5 mm toward the pole core 1 compared to the edge of the ultrasonic weld mark 4 of the lower pole core 1 .

[0060] When the edge of the ultrasonic weld mark 4 of the upper pole core 1 is retracted to 0 inward toward the pole core 1 compared to the edge of the ultrasonic weld mark 4 of the lower pole core 1, the multiple ultrasonic weld marks 4 are aligned, that is, the multiple ultrasonic weld marks 4 are arranged in a non-aligned manner (such as Figure 7 and Figure 8 shown).

[0061] When the edge of the ultrasonic weld mark 4 of the upper pole core 1 is 0-1.5 mm (excluding 0) inward toward the pole core 1 compared to the edge of the ultrasonic weld mark 4 of the lower pole core 1, the plurality of ultrasonic weld marks 4 are staggered. Figure 5 and Figure 6 shown).

[0062] When multiple ultrasonic welds 4 are completely aligned, the vertical stability of the stacked structure can be ensured. When the ultrasonic welds 4 are stacked in an offset manner, the weld positions of each layer are offset, which helps to disperse stress and prevent structural damage caused by excessive stress at a single point. This design increases the overall stability and durability of the stacked structure.

[0063] It should be noted that Figure 5-8 Part b of the figure is a partial schematic diagram corresponding to part a of the accompanying figure

[0064] In this embodiment, using the upper pressing tool to press around the welding position includes: using a single-side pressing method or a three-side pressing method to press around the welding position, and the distance between the edge of the upper pressing tool and the edge of the welding position is 0.5-2mm.

[0065] The pressing operation can ensure that the tab 2 and the cover plate adapter 3 are fitted without gaps, thereby effectively reducing deformation and displacement during welding and ensuring the accuracy and stability of the welding position, thereby improving the quality of laser welding.

[0066] In this embodiment, please refer to Fig. 9 , use laser to weld the edges of multiple ultrasonic welds 4 to the cover plate adapter plate 3, and form a lap joint 6 including: multiple ultrasonic welds 4 are stacked to form a step surface, and the laser welding width covers the step surface.

[0067] The laser welding width covers the step surface to ensure the current carrying capacity of the tab 2, thereby improving the performance and reliability of the battery.

[0068] The laser can be emitted by a vibrating mirror or an oscillating mirror. The laser track can be welded in a cross-fill, oscillating or spiral manner.

[0069] This embodiment also provides a battery assembly, including: a cover plate and a plurality of pole cores 1, wherein pole ears 2 are arranged on the pole cores 1, and the cover plate and the pole ears 2 on the plurality of pole cores 1 are welded using the welding method of the above embodiment.

[0070] This embodiment also provides a battery, including: the battery assembly of the above embodiment.

[0071] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0072] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive.

[0073] Inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "including a..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

Claims

1. A method for welding a multi-layer tab and a cover plate, characterized in that: include: Ultrasonic pre-welding is performed on each pole lug on the pole core to form an ultrasonic weld mark; Stacking and pairing the plurality of ultrasonically pre-welded pole cores, and stacking and assembling the plurality of ultrasonic weld marks and cover plate adapter sheets in space to form a welding position; Using an upper pressing tool to press the periphery of the welding position; The edges of the plurality of ultrasonic weld marks are welded together with the cover plate transfer sheet using a laser to form a lap joint.

2. The welding method of multi-layer tabs and cover plates according to claim 1, characterized in that: The pole ears of the pole core include: a positive pole ear and a negative pole ear. The positive pole ear is an aluminum alloy ear, and the thickness of the positive pole ear is 8-30um; the negative pole ear is a copper alloy ear, and the thickness of the negative pole ear is 3-20um.

3. The welding method of multi-layer tabs and cover plates according to claim 1, characterized in that: The cover plate adapter plate includes a positive electrode adapter plate or a negative electrode adapter plate. The material of the positive electrode adapter plate is aluminum alloy, and the thickness of the positive electrode adapter plate is 0.5-3mm; the material of the negative electrode adapter plate is pure copper alloy, and the thickness of the negative electrode adapter plate is 0.5-3mm.

4. The welding method of multi-layer tabs and cover plates according to claim 1, characterized in that: The number of layers of the pole ears on the pole core is 20-100.

5. The welding method of multi-layer tabs and cover plates according to claim 1, characterized in that: Before stacking and pairing the plurality of ultrasonically pre-welded pole cores, the method comprises: The central positioning principle is used to position the pole core after multiple ultrasonic pre-welding.

6. The method for welding a multi-layer electrode tab and a cover plate according to claim 1, characterized in that: The stacking manner of the plurality of ultrasonic weld marks is as follows: the edge of the ultrasonic weld mark of the upper layer of the pole core is retracted inward by 0-1.5 mm toward the pole core compared to the edge of the ultrasonic weld mark of the lower layer of the pole core.

7. The welding method of multi-layer tabs and cover plates according to claim 1, characterized in that: The method of using an upper pressing tool to press the periphery of the welding position includes: pressing the periphery of the welding position by a single-side pressing method or a three-side pressing method, and the distance between the edge of the upper pressing tool and the edge of the welding position is 0.5-2 mm.

8. The welding method of multi-layer tabs and cover plates according to claim 1, characterized in that: The method of using a laser to weld the edges of the plurality of ultrasonic welds to the cover plate adapter plate to form a lap joint comprises: a plurality of ultrasonic welds are stacked to form a step surface, and the welding width of the laser covers the step surface.

9. A battery assembly, characterized in that: include: A cover plate and a plurality of pole cores, wherein the pole cores are provided with pole ears, and the cover plate and the pole ears on the plurality of pole cores are welded by the welding method according to any one of claims 1 to 8.

10. A battery, characterized in that: include: A battery pack as claimed in claim 9.

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