Welding device and ultrasonic welding equipment

Abstract

The utility model provides a welding device and ultrasonic welding equipment. The welding device comprises a welding head, and the welding head comprises a main body part, first welding teeth and second welding teeth; the main body part is provided with a welding surface, the welding surface is provided with a first area and a second area, and the first area is located on one side of the second area in the first direction; the first welding teeth are located in the first area and arranged on the welding face in a protruding mode. The second welding teeth are located in the second area and arranged on the welding face in a protruding mode. Wherein the friction coefficient at the first region is greater than the friction coefficient at the second region. During welding, the first area is normally welded, and the stress generated by the second area at the step of the tab is small, so that the tab foil can be effectively protected, the cracking of the tab foil is reduced, the welding of the tab and the adapter plate can be completed at one time, and the welding quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding, in particular to a welding device and an ultrasonic welding equipment. BACKGROUND

[0002] With the development of new energy technology, batteries are applied more and more widely, such as in mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes, electric tools, etc.

[0003] In the battery, when the tab is connected to other structures (such as a transition sheet) by welding, the welding quality is not ideal, which affects the quality of the battery. CONTENT OF THE INVENTION

[0004] In view of the above problems, the present application provides a welding device and an ultrasonic welding equipment, which is beneficial to improve the welding quality of the tab.

[0005] In a first aspect, the present application provides a welding device, which comprises a welding head, the welding head comprising a main body, a first welding tooth and a second welding tooth; the main body has a welding surface, the welding surface being provided with a first region and a second region, the first region being located on one side of the second region in a first direction; the first welding tooth is located in the first region and protrudes from the welding surface; the second welding tooth is located in the second region and protrudes from the welding surface; wherein the friction coefficient at the first region is greater than the friction coefficient at the second region.

[0006] In the technical scheme of the present application, the welding head comprises a main body, a first welding tooth and a second welding tooth, the first welding tooth protrudes from the first region of the welding surface, and the second welding tooth protrudes from the second region of the welding surface. The welding surface of the main body can be pressed on the tab to reduce the deformation of the tab during welding, and the first welding tooth and the second welding tooth weld the tab and the transition sheet. The friction coefficient at the first region is greater than the friction coefficient at the second region, the first region is normally welded during welding, and the stress generated at the step of the tab in the second region is small, thereby effectively protecting the tab foil and reducing the cracking of the tab foil. The welding of the tab and the transition sheet can be completed at one time, and the welding quality is improved.

[0007] In some embodiments, the welding head further comprises a compensation member, the compensation member being located in the second region and protruding from the welding surface, and the second welding tooth protruding from the compensation member. The compensation member can be pressed on the step of the tab to protect the step, thereby reducing the deformation of the tab foil at the step during welding and improving the welding quality.

[0008] In some embodiments, the compensation member extends in a second direction, which is perpendicular to the first direction. The compensation member can uniformly press the free end of each tab foil on the step when it is pressed against the step, reducing the possibility of tab foil rupture and improving the welding quality.

[0009] In some embodiments, the compensation member is provided with a compensation surface, which is an end surface of the compensation member facing away from the welding surface; the compensation surface is a plane and is arranged in parallel with the welding surface, not only providing a positioning reference for the second welding tooth, but also uniformly pressing the step in the second direction, providing a good foundation for the welding of the second welding tooth to the step.

[0010] In some embodiments, in a third direction, the length of the first welding tooth is H1, the length of the second welding tooth is H2, and the length of the compensation member is ΔH; wherein H1=H2+ΔH, and the third direction is perpendicular to the welding surface. The recess pressed by the first welding tooth is deep, and the recess pressed by the second welding tooth is shallow, which is consistent with the feature that the thickness of the tab is reduced at the step, and can improve the consistency of the degree of tab compression and improve the welding quality.

[0011] In some embodiments, in the third direction, ΔH ranges from 0.05mm to 0.3mm, which can compensate for the reduced thickness of the tab at the step and press the step, and also provide a length allowance for the setting of the second welding tooth.

[0012] In some embodiments, in the third direction, the length relationship between the first welding tooth and the second welding tooth is H1=T1×N and H2=T2×N2, and N2=N-ΔH; wherein N is the total thickness of the tab to be welded, N2 is the thickness of the tab to be welded at the step, T1 is the friction coefficient at the first region, T2 is the friction coefficient at the second region, the value range of T1 is 0.5 to 0.9, and the value range of T2 is 0.3 to 0.5. By selecting the friction coefficient at the first region and measuring the total thickness of the tab, the length of the first welding tooth in the third direction can be obtained. By selecting the friction coefficient at the second region, the length of the second welding tooth can be obtained, which can provide a reference for the design of the second welding tooth and improve the welding quality at the step.

[0013] In some embodiments, the welding surface is further provided with a third region, which is located between the first region and the second region in the first direction, separating the first region from the second region, and can provide a buffer space to press the tab and reduce tab arching, reduce the vibration cracking of the free end of the tab foil, and improve the welding quality.

[0014] In some embodiments, the third region comprises a first sub-region and a second sub-region, the first sub-region is connected with the first region, and the second sub-region is connected with the second region; in the first direction, the length of the third region is A, the length of the first sub-region is D1, and the length of the second sub-region is D2; wherein A = D1 + D2, and 0 ≤ D2 / D1 ≤ 2. By designing the range of the ratio of the length of the first region to the length of the second region in the first direction, a reference can be provided for the design of the length of the third region in the first direction.

[0015] In some embodiments, in the first direction, A ranges from 1 mm to 4 mm, which not only can improve the fault tolerance of positioning during welding, reduce the positioning accuracy requirement, and improve the welding quality, but also can make the structure of the welding head more compact.

[0016] In some embodiments, in the third direction, the length of the compensation member satisfies the relationship wherein Y is the distance between the first layer of tab foils of the tab to be welded and the electrode body in the third direction, and M is the distance between the edge of the first layer of tab foils and the electrode body in the first direction. By solving the length of the compensation member in the third direction, the friction coefficient at the second region can be finally obtained, so that the parameter design of the second welding tooth is more reasonable, and the welding quality is improved.

[0017] In some embodiments, the second welding tooth is a plurality of second welding teeth, and the plurality of second welding teeth are arranged in an array on the compensation member, which can disperse the stress of the step, improve the stress of the step, and prevent the tab foil on the step from being damaged, thereby improving the welding quality.

[0018] In some embodiments, in a direction away from the welding surface, the outer contour of the first welding tooth decreases linearly; and in a cross section parallel to the welding surface, the outer contour of the first welding tooth is a convex polygon, which facilitates the extrusion of the tab by the first welding tooth, increases the friction between the first region and the tab, and improves the welding quality.

[0019] In some embodiments, in a direction away from the welding surface, the outer contour of the second welding tooth gradually decreases, and the decreasing amplitude gradually increases; and in a cross section parallel to the welding surface, the outer contour of the second welding tooth is a closed conic curve. During welding, the contact area between the second welding tooth and the step can be increased, thereby reducing the stress concentration on the step and improving the welding quality of the step.

[0020] In some embodiments, the first welding tooth is a square tooth or a triangular pyramid tooth, and the end surface of the first welding tooth facing away from the welding surface is a plane, which has strong penetration and can improve welding strength and reduce false welding; the second welding tooth is a spherical tooth, and the end surface of the second welding tooth facing away from the welding surface is an arc surface, which can reduce stress concentration when pressed on the step, has weak penetration, and thus can reduce tab cracking and improve welding quality.

[0021] In a second aspect, the present application provides an ultrasonic welding device, which comprises an ultrasonic oscillator and the welding device in the above embodiments, and the welding device is connected to the ultrasonic oscillator.

[0022] The above description is only a summary of the technical solutions of the present application. In order to enable one of ordinary skill in the art to better understand the technical means of the present application and implement it according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not meant to limit the present application. Moreover, the same reference numerals in the attached drawings refer to the same or similar components. In the drawings:

[0024] Figure 1 Schematic view of the welding of the electrode assembly and the adapter piece;

[0025] Figure 2 Schematic view of the welding of the electrode assembly and the adapter piece; Figure 1 Schematic view of the welding of the electrode assembly and the adapter piece;

[0026] Figure 3 Schematic view of the welding of the electrode assembly and the adapter piece;

[0027] Figure 4 Schematic view of the welding of the electrode assembly and the adapter piece;

[0028] Figure 5 Schematic view of the welding of the electrode assembly and the adapter piece;

[0029] Figure 6 Schematic view of the welding of the electrode assembly and the adapter piece; Figure 5 Schematic view of the welding of the electrode assembly and the adapter piece;

[0030] Figure 7 Schematic view of the welding of the electrode assembly and the adapter piece; Figure 6 Schematic view of the welding of the electrode assembly and the adapter piece;

[0031] Figure 8 Schematic view of the welding of the electrode assembly and the adapter piece; Figure 6Structure schematic view of the first welding tooth;

[0032] Figure 9 Structure schematic view of the welding head of some embodiments of the present application from one perspective;

[0033] Figure 10 Structure schematic view of the welding head of some embodiments of the present application from one perspective;

[0034] Figure 11 Structure schematic view of the welding head of some embodiments of the present application from one perspective; Figure 10 Partial enlarged schematic view at III;

[0035] Figure 12 Structure schematic view of the welding head of some embodiments of the present application from one perspective; Figure 11 Partial enlarged schematic view at IV;

[0036] Figure 13 Structure schematic view of the welding head of some embodiments of the present application from one perspective;

[0037] Figure 14 Structure schematic view of the welding head of some embodiments of the present application from one perspective;

[0038] Figure 15 Structure schematic view of the welding head of some embodiments of the present application from one perspective; Figure 14 Structure schematic view of the welding head of some embodiments of the present application from one perspective;

[0039] Figure 16 Structure schematic view of the first welding tooth of some embodiments of the present application from one perspective. Figure 15 Reference numerals in the detailed description are as follows:

[0040] 100 - electrode main body; 200 - tab; 210 - total thickness part; 220 - step; 300 - adapter; 10 - welding device; 20 - ultrasonic oscillator;

[0041] 1 - welding head; 2 - main body part; 21 - welding surface; 211 - first area; 212 - second area; 213 - third area; 2131 - first sub-area; 2132 - second sub-area; 3 - first welding tooth; 4 - compensation member; 5 - second welding tooth;

[0042] x - first direction; y - second direction; z - third direction.

[0043] DETAILED DESCRIPTION The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0044]

[0045] ​Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof. Unless otherwise required by context, singular terms shall include pluralities and vice versa. Unless otherwise required by context, the use herein of the singular is also to be construed as a use of the plural and vice versa.

[0046] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly and specifically limited.

[0047] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification is not necessarily all referring to the same embodiment, or to a particular embodiment, or to a particular set of embodiments. It will be explicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0048] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0049] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0050] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0051] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, or detachable connection, or integrated; can be mechanical connection, or electrical connection; can be direct connection, or indirect connection through an intermediate medium, or internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0052] At present, the application of power battery is more and more extensive, and the power battery is not only applied to the energy storage power supply system of hydroelectric, thermal, wind and solar power stations, but also widely applied to electric bicycles, electric motorcycles, electric vehicles, electric vehicles, military equipment and aerospace and many other fields. With the continuous expansion of the application field of power battery, its market demand is also increasing.

[0053] Please refer to Figure 1 and Figure 2 , Figure 1 is a schematic view of the welding of the electrode assembly and the adapter piece; Figure 2 is Figure 1 a local enlarged schematic view at I.

[0054] The power battery comprises one or more battery monomers, and the battery monomer is provided with an electrode assembly, the electrode assembly comprises an electrode main body 100 and a tab 200, the tab 200 is provided in a plurality of tab foil layers, and the tab 200 is connected by welding when connected with other structures (for example, an adapter piece 300).

[0055] When welding the tab 200, ultrasonic welding is a kind of efficient welding method. Ultrasonic welding is to use high-frequency vibration wave to transmit to the surfaces of two objects to be welded, and under the condition of pressure, the surfaces of the two objects are rubbed to form the fusion between the molecular layers, which has the advantages of high efficiency, high quality, energy saving, high welding strength and the like.

[0056] The tab 200 is generally connected with the adapter piece 300 in a lap joint structure. When welding, the ultrasonic welding head is pressed on the plurality of tab foils provided in layers, and a certain pressure is applied through the ultrasonic welding head, and then the ultrasonic device outputs ultrasonic waves, and the atomic resonance of the adjacent tab foils and the tab foil and the adapter piece 300 is realized under high-frequency vibration, and then the plurality of tab foils and the tab 200 and the adapter piece 300 are connected together.

[0057] Since the tab foil is very thin, generally only 5-20 μm for a single layer, when the number of layers exceeds 30, in order to ensure the welding quality, generally two times of welding are carried out, one pre-welding and one final welding. For example Figure 1 andFigure 2 As shown, before pre-welding, due to the shaping of the tab 200, a step 220 is formed at the end (since the multiple tab foils are extended from the electrode body 100 at the same length, when the multiple tab foils are stacked on one side of the electrode body 100, the tab 200 forms a stepped structure at the end away from the electrode body 100, which is called the step 220), and after pre-welding at the step 220 position, the edge of the tab foil is slightly arched. During ultrasonic final welding, this area will interfere with the ultrasonic welding joint due to the arching, resulting in a large difference in welding energy between this area and the surrounding area, which is prone to cause the first layer of tab foil or multiple layers of tab foil to crack, thereby affecting the quality of the battery cell. Among them, the area corresponding to the first layer of tab foil welded during pre-welding (referred to as the total thickness part 210) and the step 220 are welded again by selecting a welding tooth with a shallow tooth height during final welding, and two welds are performed.

[0058] In related technologies, one measure to improve tab 200 cracking is to increase the pre-welding compaction area at the edge of the ultrasonic welding joint, which compacts the area of the tab 200 that arches after pre-welding, and is less likely to cause cracking when welded nearby the second time. However, this measure can only be applied to the case where the tab 200 is long, and there is not enough space to increase the pre-welding compaction area for the electrode assembly with a short tab 200, so it cannot be applied, and tab 200 cracking cannot be avoided. Another measure to improve tab 200 cracking is to add a protective sheet to the multiple tab 200 to protect the tab 200, so that most of the force of the ultrasonic welding joint high-frequency vibration acts on the protective sheet, but enough energy is transmitted to the tab 200 to effectively weld the tab 200. However, when the protective sheet is placed on the tab 200, the position is easy to shift, and when it is skewed, it may be inserted into the positive and negative tabs to cause thermal runaway, which has been gradually canceled in the industry. Therefore, there is no good measure to improve the welding condition of the tab 200 in related technologies.

[0059] In order to reduce the cracking of the tab 200, the stress at the step 220 can be improved to improve the welding quality of the tab 200. Specifically, the structure of the welding joint 1 can be improved, and the friction coefficient during welding is reduced corresponding to the step 220 area of the tab 200, so as to reduce the force applied by the welding joint 1 to the step 220, thereby improving the force applied by the welding joint 1 to the tab 200.

[0060] In the welding device 10, the main body 2 of the welding head 1 is provided with a first region 211 and a second region 212 on the welding surface 21, the first welding teeth 3 are arranged on the first region 211, and the second welding teeth 5 are arranged on the second region 212. By arranging the first welding teeth 3 and the second welding teeth 5 differently, the friction coefficients at the first region 211 and the second region 212 are distinguished, so that the friction force at the first region 211 is greater than the force at the second region 212 during welding. The total thickness part 210 of the tab 200 is stressed, and the tab 200 can be normally welded. The step 220 of the tab 200 is less stressed, and the cracking during welding can be reduced. During welding, the first region 211 covers the total thickness part 210 of the tab 200, and the second region 212 covers the step 220 of the tab 200, so as to reduce the stress of the tab foil at the step 220. Moreover, by arranging the first region 211 and the second region 212 with different friction coefficients, the welding of the tab 200 and the adapter plate 300 can be completed at one time, the welding times are reduced, the cracking of the tab 200 is reduced, and the welding quality of the tab 200 is improved.

[0061] The welding device 10 disclosed by the embodiments of the present application can be applied to ultrasonic welding equipment using ultrasonic welding technology. The ultrasonic welding equipment can be, but is not limited to, a handheld ultrasonic welding machine, a plastic ultrasonic welding machine, and a metal ultrasonic welding machine.

[0062] The following embodiments are described by taking the metal ultrasonic welding machine as an example for the convenience of description.

[0063] Please refer to Figure 3 , Figure 3 for the structural schematic diagram of the ultrasonic welding equipment of some embodiments of the present application.

[0064] The metal ultrasonic welding machine can include an ultrasonic oscillator 20 and a welding device 10. The welding device 10 is driven by the ultrasonic oscillator 20 to make the welding head 1 vibrate at a high frequency. The welding surface 21 of the welding head 1 is pressed against a workpiece. The part of the workpiece pressed by the first welding teeth 3 and the second welding teeth 5 is fused under the action of the high-frequency vibration of the first welding teeth 3 and the second welding teeth 5, so that welding is achieved.

[0065] As an example of the embodiments, as shown in Figure 1 and Figure 2 , the workpiece is a tab 200 to be welded and an adapter plate 300. The tab foil of the electrode assembly is arranged in layers after shaping. The tab 200 forms a step 220 at an end away from the electrode main body 100. The part of the tab 200 outside the step 220 is a total thickness part 210. The tab 200 is arranged above the adapter plate 300, and the step 220 is in a welding area. During welding, the welding head 1 approaches and presses the tab 200 from above the tab 200. Through the high-frequency vibration and displacement of the welding head 1, the tab 200 and the adapter plate 300 can be welded together.

[0066] Please refer to Figures 4 to 10 , Figure 4 is a structural schematic diagram of a welding device according to some embodiments of the present application from one perspective; Figure 5 is a structural schematic diagram of a welding device according to some embodiments of the present application from another perspective; Figure 6 is a structural schematic diagram of a welding device according to some embodiments of the present application from another perspective; Figure 5 is a local enlarged schematic diagram at II; Figure 7 is a structural schematic diagram of a welding device according to some embodiments of the present application from another perspective; Figure 6 is a schematic diagram of the connection between the compensation member and the second welding tooth in the welding device according to some embodiments of the present application; Figure 8 is a structural schematic diagram of a welding device according to some embodiments of the present application from another perspective; Figure 6 is a structural schematic diagram of a welding device according to some embodiments of the present application from another perspective; Figure 9 is a structural schematic diagram of a welding head according to some embodiments of the present application from one perspective; Figure 10 is a structural schematic diagram of a welding head according to some other embodiments of the present application from one perspective.

[0067] The embodiments of the present application provide a welding device 10, which comprises a welding head 1, the welding head 1 comprising a main body 2, a first welding tooth 3 and a second welding tooth 5. The main body 2 has a welding surface 21, which is provided with a first region 211 and a second region 212, the first region 211 being located on one side of the second region 212 in a first direction x. The first welding tooth 3 is located in the first region 211 and protrudes from the welding surface 21; the second welding tooth 5 is located in the second region 212 and protrudes from the welding surface 21. The friction coefficient at the first region 211 is greater than the friction coefficient at the second region 212.

[0068] The welding head 1 is the part of the welding device 10 that presses against the tab 200, and the welding head 1 presses against the tab 200 through the welding surface 21 of the main body 2. The welding surface 21 can press the tab 200 tightly during welding, thereby reducing the deformation of the tab 200. The first region 211 and the second region 212 are arranged on the welding surface 21 along the first direction x, and the position relationship between the welding head 1 and the tab 200 during welding is taken as a reference, and the first direction x is the direction in which the tab 200 extends from the electrode main body 100. The first region 211 is closer to the electrode main body 100, and the second region 212 is farther away from the electrode main body 100.

[0069] The welding surface 21 can have various shapes, such as a rectangle, a circle, an ellipse, etc. Exemplarily, the welding surface 21 is rectangular, the first direction x is parallel to the short side of the rectangle, the first region 211 is a region on the welding surface 21 with a rectangular outer contour, and the second region 212 is another region on the welding surface 21 with a rectangular outer contour.

[0070] The first welding tooth 3 is located in the first area 211 and protrudes from the welding surface 21. During welding, the first welding tooth 3 is used to press the thick part 210 of the tab 200, promote the friction between the thick part 210 and the connecting piece, and form the fusion between the molecular layers.

[0071] The first welding tooth 3 and the main body 2 can be designed as a split type or integrally formed. The number of the first welding tooth 3 can be one or multiple.

[0072] When the number of the first welding tooth 3 is one, a plurality of protruding ribs can be machined on the first welding tooth 3 to increase the area. Alternatively, no ribs can be machined on the first welding tooth 3, and the surface of the first welding tooth 3 can be a plurality of planes and / or curved surfaces.

[0073] When the number of the first welding tooth 3 is multiple, the multiple first welding teeth 3 can be randomly distributed or arrayed in the first area 211. When the multiple first welding teeth 3 are arrayed, the array can be circumferentially arrayed or rectangularly arrayed.

[0074] When the multiple first welding teeth 3 are rectangularly arrayed, the rows of the array can be along the first direction x, and the columns of the array can be perpendicular to the first direction x. The distance between two adjacent first welding teeth 3 in the same row can be equal to or different from the distance between two adjacent first welding teeth 3 in the same column.

[0075] The second welding tooth 5 is located in the second area 212 and protrudes from the welding surface 21. During welding, the second welding tooth 5 is used to press the step 220, promote the friction between the multiple layers of the tab 200 foil and the connecting piece at the pressed part, and form the fusion between the molecular layers.

[0076] The second welding tooth 5 and the main body 2 can be designed as a split type or integrally formed. The number of the second welding tooth 5 can be one or multiple.

[0077] When the number of the second welding tooth 5 is one, a plurality of protruding ribs can be machined on the second welding tooth 5. Alternatively, no ribs can be machined on the second welding tooth 5, and the surface of the second welding tooth 5 can be a plurality of planes and / or curved surfaces.

[0078] When the number of the second welding tooth 5 is multiple, the multiple second welding teeth 5 can be randomly distributed or circumferentially arrayed or rectangularly arrayed in the second area 212.

[0079] When the multiple second welding teeth 5 are rectangularly arrayed, the rows of the array can be along the first direction x, and the columns of the array can be perpendicular to the first direction x. The distance between two adjacent second welding teeth 5 in the same row can be equal to or different from the distance between two adjacent second welding teeth 5 in the same column.

[0080] When the number of the second welding teeth 5 and the number of the first welding teeth 3 are both plural, the distance between two adjacent first welding teeth 3 can be equal to the distance between two adjacent second welding teeth 5, or can not be equal to the distance between two adjacent second welding teeth 5.

[0081] The first welding teeth 3 and the second welding teeth 5 are both convex on the welding surface 21, and the length of the convexity of the first welding teeth 3 and the second welding teeth 5 can be equal or can not be equal in the direction away from the welding surface 21.

[0082] When the friction coefficient of the first region 211 is greater than the friction coefficient of the second region 212 on the welding head 1, the stress on the step 220 caused by the second welding teeth 5 is less than the stress on the total thickness part 210 caused by the first welding teeth 3 during welding. When setting the friction coefficients of the first region 211 and the second region 212, the friction coefficient of the first region 211 can be set to be large and the friction coefficient of the second region 212 can be set to be small by various forms.

[0083] Exemplarily, the friction coefficients of the first region 211 and the second region 212 can be distinguished by setting the shapes of the first welding teeth 3 and the second welding teeth 5. The surface of the first welding teeth 3 can be rough (a plurality of edges exist on the outer surface of the first welding teeth 3), and the surface of the second welding teeth 5 can be smooth (no edge exists on the outer surface of the second welding teeth 5 or the number of edges on the outer surface of the second welding teeth 5 is less than the number of edges on the outer surface of the first welding teeth 3), so as to distinguish the friction coefficients of the first region 211 and the second region 212.

[0084] Exemplarily, the friction coefficients of the first region 211 and the second region 212 can be adjusted by setting the number of the first welding teeth 3 and the second welding teeth 5. When the number of the first welding teeth 3 and the number of the second welding teeth 5 are both plural, the distance between two adjacent first welding teeth 3 can be less than the distance between two adjacent second welding teeth 5. The first welding teeth 3 are densely distributed in the first region 211, and the second welding teeth 5 are sparsely distributed in the second region 212.

[0085] In the above embodiment, the welding head 1 comprises the main body 2, the first welding tooth 3 and the second welding tooth 5, the welding surface 21 of the main body 2 can be pressed on the tab 200 to reduce the deformation of the tab 200 during welding, the first welding tooth 3 extrudes the total thickness part 210, and the second welding tooth 5 extrudes the step 220, so that the tab 200 can form a first welding mark under the action of the first welding tooth 3 and a second welding mark under the action of the second welding tooth 5. The friction coefficient at the first region 211 is greater than the friction coefficient at the second region 212, the total thickness part 210 of the tab 200 has a large stress during welding, normal welding can be achieved, the step 220 has a small stress, the tab foil can be effectively protected, the cracking of the tab foil can be reduced, and the welding quality can be improved. Moreover, the welding device 10 is provided with the first region 211 and the second region 212, the first welding tooth 3 is arranged in the first region 211, and the second welding tooth 5 is arranged in the second region 212, so that the number of welding times can be reduced, and the step 220 and the total thickness part 210 of the tab 200 can be welded at one time, thereby reducing the damage to the tab 200 caused by multiple welding.

[0086] As shown in Figures 7 to 10 According to some embodiments of the present application, the welding head 1 further comprises a compensation member 4, the compensation member 4 is located in the second region 212 and protrudes from the welding surface 21, and the second welding tooth 5 protrudes from the compensation member 4.

[0087] The compensation member 4 is located in the second region 212 and can be designed in a separate form from the welding surface 21 or integrally formed with the welding surface 21. When arranged on the welding surface 21, the compensation member 4 protrudes outward from the welding surface 21 and provides a position for the second welding tooth 5, and the second welding tooth 5 protrudes outward from the compensation member 4.

[0088] The surface of the compensation member 4 away from the welding surface 21 can have various shapes, for example, the surface can be an arc surface or a flat surface, and when the surface is a flat surface, the surface can be parallel to the welding surface 21 or parallel to the inclined direction of the step 220.

[0089] On the welding surface 21, the number of compensation members 4 can be one or more. When the number of compensation members 4 is one, the compensation member 4 can cover part of the second region 212 of the welding surface 21 or cover the entire second region 212 of the welding surface 21. When the compensation member 4 covers part of the second region 212 of the welding surface 21, the compensation member 4 can be in a strip shape, and the extension direction of the compensation member 4 is perpendicular to the first direction x. When the number of compensation members 4 is more than one, the plurality of compensation members 4 can be arranged at equal intervals along the first direction x or at equal intervals perpendicular to the first direction x.

[0090] In the welding, the welding surface 21 presses against the total thickness part 210, and presses on the surface of the first layer of tab foil. The thickness of the tab 200 at the step 220 is reduced, and cannot be pressed tightly. The compensation part 4 is convex on the welding surface 21 at the second area 212, and can press on the step 220 to press the step 220 tightly, and compensate the pressing force at the step 220.

[0091] In the above embodiment, the compensation part 4 is convex on the welding surface 21 at the second area 212, and the second welding tooth 5 is convex on the compensation part 4. In the welding, the part of the welding surface 21 at the first area 211 presses on the first layer of tab foil, and the compensation part 4 presses on the step 220, which can protect the step 220, and reduce the deformation of the tab foil at the step 220 in the welding, and improve the welding quality.

[0092] As shown in Figure 9 and Figure 10 According to some embodiments of the present application, optionally, the compensation part 4 extends in a second direction y, and the second direction y is perpendicular to the first direction x.

[0093] The first direction x and the second direction y are directions defined based on the welding surface 21, and both are parallel to the welding surface 21. Moreover, based on the position relationship between the welding surface 21 and the electrode assembly in the welding, the first direction x is also the direction of the tab 200 extending from the electrode main body 100, and the thickness of the step 220 gradually decreases along the first direction x. The second direction y is perpendicular to the first direction x, and further, the second direction y is parallel to the edge of the free end of the tab foil.

[0094] In the above embodiment, the compensation part 4 extends in the second direction y, and when pressing on the step 220, the free end of each tab foil at the step 220 can be pressed uniformly, and the possibility of the tab foil breaking can be reduced, and thus the welding quality can be improved.

[0095] As shown in Figure 6 and Figure 7 According to some embodiments of the present application, optionally, the compensation part 4 is provided with a compensation surface, and the compensation surface is an end surface of the compensation part 4 away from the welding surface 21. The compensation surface is a plane, and the compensation surface is arranged in parallel to the welding surface 21.

[0096] In the welding, the compensation surface presses on the step 220, and can effectively fix the step 220. The compensation surface is an end surface of the compensation part 4 away from the welding surface 21, and the compensation part 4 is further provided with a side surface connected with the compensation surface. When the side surface is connected with the compensation surface, the side surface and the compensation surface can be connected in a smooth transition; or the side surface and the compensation surface can form an edge at the intersection, and the side surface and the compensation surface form an included angle, and the included angle can be a right angle, or an obtuse angle; or a part of the side surface and the compensation surface are connected in a smooth transition, and another part of the side surface and the compensation surface form an edge at the intersection.

[0097] In the above embodiment, the compensation surface is a plane, which facilitates providing a positioning reference for the second welding tooth 5. The compensation surface is parallel to the welding surface 21, which allows the step 220 to be uniformly pressed in the second direction y, providing a good foundation for the welding of the second welding tooth 5 to the step 220.

[0098] like Figures 6 to 8 As shown, according to some embodiments of this application, optionally, on the third direction z, the length of the first welding tooth 3 is H1, the length of the second welding tooth 5 is H2, and the length of the compensation member 4 is ΔH; wherein, H1=H2+ΔH, and the third direction z is perpendicular to the welding surface 21.

[0099] The third direction z is the direction in which the first welding tooth 3, the second welding tooth 5, and the compensating part 4 protrude outward on the welding surface 21. The third direction z, the second direction y, and the first direction x are perpendicular to each other.

[0100] On the third direction z, the length of the first welding tooth 3 is equal to the sum of the lengths of the compensating member 4 and the second welding tooth 5. The distance between the free end of the first welding tooth 3 and the welding surface 21 is equal to the distance between the free end of the second welding tooth 5 and the welding surface 21.

[0101] During welding, because the thickness of step 220 is small, the first welding tooth 3 first contacts and presses against the surface of the first layer of electrode foil, and then the second welding tooth 5 contacts and presses against step 220.

[0102] The tab 200 is relatively weak at the step 220. If H1 < H2 + ΔH, the second welding tooth 5 will contact and squeeze the step 220 first during welding, which will cause the tab foil at the step 220 to shift, deform or even break. It is also easy to cause overpressure (excessive pressure) and damage the tab 200. If H1 > H2 + ΔH, the second welding tooth 5 and the step 220 may not be able to reach the predetermined pressure during welding, resulting in a poor weld.

[0103] In the above embodiment, during welding, the first welding tooth 3 presses against the total thickness 210, causing the total thickness 210 to indent at the pressure point, and the welding surface 21 presses against the surface of the first layer of electrode foil; the second welding tooth 5 presses against the step 220, causing the step 220 to indent at the pressure point, and the compensating member 4 presses against the surface of the step 220. In the third direction z, the length of the first welding tooth 3 is equal to the sum of the lengths of the compensating member 4 and the second welding tooth 5. The length of the first welding tooth 3 is greater than the length of the second welding tooth 5. The indentation of the total thickness 210 is deep, while the indentation of the step 220 is shallow, which conforms to the characteristic of the electrode 200 thinning at the step 220. This can improve the consistency of the pressure on the electrode 200 at the step 220 and the total thickness 210, reduce power difference, thereby reducing electrode 200 cracking and improving welding quality.

[0104] like Figure 6 and Figure 7As shown, according to some embodiments of the present application, optionally, in the third direction z, the range of AH is 0.05mm to 0.3mm.

[0105] In the third direction z, the height of the compensation piece 4 protruding from the surface of the welding surface 21 is 0.05mm to 0.3mm, and exemplarily, AH can be any value in 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, or any intermediate value between any two adjacent values.

[0106] In the above embodiments, the range of AH is 0.05mm to 0.3mm, which can compensate for the reduced thickness of the tab 200 at the step 220, and also provide a length allowance for the setting of the second welding tooth 5.

[0107] As shown in Figure 7 and Figure 8 As shown, according to some embodiments of the present application, optionally, in the third direction z, the length relationship between the first welding tooth 3 and the second welding tooth 5 is H1=T1xN, H2=T2xN2, N2=N-AH. Wherein, N is the total thickness of the tab 200 to be welded, N2 is the thickness of the tab 200 to be welded at the step 220, T1 is the friction coefficient at the first region 211, and T2 is the friction coefficient at the second region 212. The value range of T1 is 0.5 to 0.9, and the value range of T2 is 0.3 to 0.5.

[0108] N is the total thickness of the tab 200 to be welded, which is the sum of the thicknesses from the first layer of tab foil to the last layer of tab foil in the third direction z, that is, the thickness of the total thick portion 210. N2 is the thickness of the tab 200 to be welded at the step 220, which is the thickness calculated for the step 220, and is set as the difference between the total thickness of the tab 200 to be welded and the length of the compensation piece 4. T1 is the friction coefficient of the uneven surface formed by the outer surface of the first welding tooth 3 and the welding surface 21 in the first region 211. T2 is the friction coefficient of the uneven surface formed by the outer surface of the second welding tooth 5, the outer surface of the compensation piece 4, and the welding surface 21 in the second region 212.

[0109] The value range of T1 is 0.5 to 0.9, and exemplarily, it can be any value in 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or any intermediate value between any two adjacent values.

[0110] T2 is in the range of 0.3 to 0.5, and can be any of 0.3, 0.35, 0.4, 0.45, 0.5, or any intermediate value between any two adjacent values.

[0111] In the above embodiment, H1 = T1 x N, H2 = T2 x N2, N2 = N - ΔH, the length of the first welding tooth 3 in the third direction z can be obtained by selecting the friction coefficient at the first region 211 and measuring the total thickness of the lug 200. The length of the second welding tooth 5 can be obtained by selecting the friction coefficient at the second region 212, thereby providing a reference for the design of the second welding tooth 5 and improving the welding quality at the step 220.

[0112] Please refer to Figure 11 and Figure 12 , Figure 11 for Figure 10 a local enlarged view at III; Figure 12 for Figure 11 a local enlarged view at IV.

[0113] According to some embodiments of the present application, the welding surface 21 further comprises a third region 213, which is located between the first region 211 and the second region 212 in the first direction x.

[0114] In the first direction x, a gap is provided between the first region 211 and the second region 212, and the gap is the third region 213. Illustratively, the welding surface 21 is divided into three regions, which are the first region 211, the third region 213 and the second region 212 in the first direction x, and the third region 213 is located between the first region 211 and the second region 212. When the welding surface 21 has an outer contour in the shape of a rectangle, the first region 211, the second region 212 and the third region 213 are three small rectangles.

[0115] The first welding tooth 3 is located in the first region 211, the second welding tooth 5 and the compensation member 4 are located in the second region 212, and the third region 213 is only the welding surface 21, which provides a gap for the first region 211 and the second region 212. If the third region 213 is not provided, the first region 211 and the second region 212 are connected, and a higher positioning accuracy is required during welding to ensure that the first region 211 is pressed against the total thickness portion 210 and the second region 212 is pressed against the step 220. If the positioning accuracy is low, the possibility of interference during welding is increased.

[0116] The interference refers to the invasion of the first region 211 and the second region 212 to each other at the welding position corresponding to each other when welding. If the first region 211 is pressed on the total thickness part 210 and a part of the step 220, and if the second region 212 is pressed on the step 220 and a part of the total thickness part 210, the interference occurs.

[0117] Exemplarily, if the third region 213 is not arranged on the welding surface 21, when welding, it is possible that a part of the first region 211 is pressed on the step 220, the stress at the step 220 is increased, and the tab foil is easily broken; it is also possible that a part of the second region 212 is pressed on the total thickness part 210, and the false welding is easily caused.

[0118] In the above embodiment, the welding surface 21 is separated into the first region 211 and the second region 212 by arranging the third region 213 between the first region 211 and the second region 212, so that the buffer space is left, the first region 211 corresponds to the total thickness part 210, the second region 212 corresponds to the step 220, and the third region 213 corresponds to the junction of the total thickness part 210 and the step 220. The arrangement of the third region 213 can reduce the interference of the first region 211 and the second region 212 at the welding position, the third region 213 is pressed on a part of the free end of the tab foil when welding, which can reduce the arching of the tab foil, reduce the cracking of the free end of the tab foil due to vibration, and improve the welding quality.

[0119] As shown in FIG. 2, according to some embodiments of the present application, the third region 213 includes a first sub-region 2131 and a second sub-region 2132, the first sub-region 2131 is connected with the first region 211, and the second sub-region 2132 is connected with the second region 212. Figure 12 As shown in FIG. 2, according to some embodiments of the present application, the third region 213 includes a first sub-region 2131 and a second sub-region 2132, the first sub-region 2131 is connected with the first region 211, and the second sub-region 2132 is connected with the second region 212.

[0120] In the first direction x, the third region 213 is divided into the first sub-region 2131 and the second sub-region 2132. Here, the division of the third region 213 is not a physical division, and does not cause the difference in appearance, structure and performance between the first sub-region 2131 and the second sub-region 2132.

[0121] When the first sub-region 2131 and the second sub-region 2132 are divided from the third region 213, the distance D1 from the first region 211 to the reference is taken as the reference, and the distance D2 from the second region 212 to the reference is taken as the reference.

[0122] When welding, the first welding tooth 3 is required to leave a safe space from the free end of the first layer tab foil to reduce the pulling and tearing of the tab 200; the second welding tooth 5 is required to be as close as possible to the free end of the first layer tab foil to reduce the pulling force at the step 220 and improve the welding space. In the first direction x, the ratio of the length of the second sub-region 2132 to the length of the first sub-region 2131 is 0 to 2, and the ratio can be any value in 0, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, or any intermediate value between any two adjacent values. When the ratio is 0, A=D1.

[0123] In the above embodiment, by designing the ratio range of the length of the first region 211 to the length of the second region 212 in the first direction x, a reference can be provided for the length design of the third region 213 in the first direction x.

[0124] As shown in FIG. 13, according to some embodiments of the present application, optionally, in the first direction x, A ranges from 1 mm to 4 mm. Figure 12

[0125] The length of the third region 213 in the first direction x ranges from 1 mm to 4 mm, and can be any value in 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, or any intermediate value between any two adjacent values.

[0126] In the above embodiment, the lower limit of the length of the third region 213 in the first direction x is 1 mm, which can improve the fault tolerance of positioning during welding, reduce the positioning accuracy requirement, and improve the welding quality; the upper limit of the length of the third region 213 in the first direction x is 4 mm, which does not excessively increase the size of the welding head 1 in the first direction x, and can make the welding head 1 structure more compact.

[0127] As shown in FIG. 14 and FIG. 15, according to some embodiments of the present application, optionally, in the third direction z, the length of the compensation member 4 satisfies the relationship Figure 6 Figure 7 wherein Y is the distance of the first layer tab foil of the tab 200 to be welded from the electrode body 100 in the third direction z, and M is the distance of the edge (the edge of the free end of the first layer tab foil) of the first layer tab foil from the electrode body 100 in the first direction x.

[0128] wherein, ​​​L is the theoretical length of the step 220, which can be the length of the line segment connecting the free end of the first layer of tab foil and the free end of the last layer of tab foil in the first direction x. The length of the step 220 is determined by the thickness of the electrode body 100 and the position of the free end of the tab 200 after shaping, both of which are fixed values, so that the length of the step 220 is a fixed value after the electrode assembly is shaped, which can be calculated according to the electrode assembly.

[0129] The length of the unit thickness tab can be obtained from the theoretical length of the step 220 and the total thickness of the tab 200 to be welded, i.e. X = L / N.

[0130] The length of the compensation member 4 in the third direction z can be obtained from the length of the unit thickness tab and the length of the second sub-region 2132, i.e. AH = D2X.

[0131] From H1 = H2 + AH and H1 = T1N, it can be obtained that When T1 and D2 are selected and N, Y and M are measured, the length of the second welding tooth 5 in the third direction z can be obtained.

[0132] From H2 = T2N2 and N2 = N - AH, it can be obtained that T2 = H2 / (N - AH), and the friction coefficient at the second region 212 can be obtained.

[0133] In the above embodiment, the friction coefficient at the second region 212 can be finally obtained by solving the length of the compensation member 4 in the third direction z. According to the specific parameters of the step 220, the friction coefficient at the second region 212 is provided instead of being selected subjectively, which can make the parameter design of the second welding tooth 5 more reasonable, thereby further improving the stress at the step 220 during welding and improving the welding quality.

[0134] When D2 / D1 = 0, the compensation member 4 is not provided on the welding head 1, and the friction coefficient at the second region 212 is selected according to the subjective selection at this time.

[0135] Please refer to Figure 13 and Figure 14 , Figure 13 is a structural schematic view of the welding head of some embodiments of the present application in one perspective; Figure 14 is a structural schematic view of the welding head of some embodiments of the present application in one perspective.

[0136] According to some embodiments of the present application, the second welding tooth 5 can be multiple, and the multiple second welding teeth 5 are arranged in an array on the compensation member 4.

[0137] In the second region 212, the number of compensation members 4 can be one or multiple, such as Figure 13As shown, the compensation member 4 is one, and a plurality of second welding teeth 5 can be protruded on the compensation member 4. Figure 14 As shown, the compensation member 4 is one, and a plurality of second welding teeth 5 can be protruded on the compensation member 4.

[0138] When the plurality of second welding teeth 5 are arrayed on the compensation member 4 in the first direction x as rows and in the second direction y as columns, the second welding teeth 5 can be arranged in one row and multiple columns, two rows and multiple columns, three rows and multiple columns, four rows and multiple columns, and the like. Here, the multiple columns refer to that in the second direction y, the number of second welding teeth 5 in each column is not less than 6, for example, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, and the like, but is not limited to even numbers, and can also be an odd number greater than 6. Correspondingly, the first welding teeth 3 are arranged in a rectangular array in the first area 211.

[0139] In the above embodiments, the plurality of second welding teeth 5 are arrayed on the compensation member 4, and the second welding teeth 5 are multiple, which can disperse the stress of the step 220 during welding, improve the stress of the step 220, and prevent the foil of the tab 200 on the step 220 from being damaged, thereby improving the welding quality.

[0140] Please refer to Figure 15 and Figure 16 , Figure 15 is a structural schematic view of the welding head in Figure 14 from another perspective; Figure 16 is a structural schematic view of the first welding tooth in Figure 15 .

[0141] According to some embodiments of the present application, optionally, the outer contour of the first welding tooth 3 linearly decreases in a direction away from the welding surface 21. In a cross section parallel to the welding surface 21, the outer contour of the first welding tooth 3 is a convex polygon.

[0142] In the third direction z, the outer contour of the first welding tooth 3 linearly decreases. The outer contour of the first welding tooth 3 is a convex polygon, and the end surface of the first welding tooth 3 away from the welding surface 21 is a convex polygon. The convex polygon can be a triangle, a quadrilateral, a pentagon, a hexagon, and the like.

[0143] Exemplarily, the end surface of the first welding tooth 3 away from the welding surface 21 is a rectangle. The first welding tooth 3 has four side surfaces, each of which is a plane, and each side surface forms an obtuse angle with the end surface of the first welding tooth 3 away from the welding surface 21. The first welding tooth 3 is a rectangular welding tooth.

[0144] For example, the outer contour of the end face of the first welding tooth 3 facing away from the welding surface 21 is an equilateral triangle. The first welding tooth 3 has three sides, all of which are planes, and each side forms an obtuse angle with the end face of the first welding tooth 3 facing away from the welding surface 21. The first welding tooth 3 is a triangular pyramidal welding tooth.

[0145] In the above embodiment, the outer contour of the first welding tooth 3 decreases linearly in the third direction z, which facilitates the first welding tooth 3 to squeeze the tab 200, increase the friction between the first region 211 and the tab 200, and improve the welding quality.

[0146] like Figure 15 As shown, according to some embodiments of this application, optionally, the outer contour of the second weld tooth 5 gradually decreases along the direction away from the welding surface 21, and the rate of decrease gradually increases. On a cross-section parallel to the welding surface 21, the outer contour of the second weld tooth 5 is a closed conic curve.

[0147] A closed conic section is a curve formed by the intersection of a cone with any plane and the cone's surface.

[0148] Along the third direction z, the outer contour of the second welding tooth 5 gradually decreases, and the rate of decrease gradually increases. The outer contour of the second welding tooth 5 on the section parallel to the welding surface 21 is one or more conic curves, for example, the outer contour of the second welding tooth 5 on the section parallel to the welding surface 21 is circular; the outer contour of the second welding tooth 5 on the section parallel to the welding surface 21 is elliptical; it can also be that part of the second welding tooth 5 has a circular outer contour on the section parallel to the welding surface 21, and another part of the second welding tooth 5 has an elliptical outer contour on the section parallel to the welding surface 21.

[0149] For example, on a cross section parallel to the welding surface 21, the outer contour of the second welding tooth 5 is circular; on the third direction z, the end face of the second welding tooth 5 away from the welding surface 21 is an arc surface, which smoothly transitions with the side surface of the second welding tooth 5, and thus the entire outer surface of the second welding tooth 5 is part of a spherical surface (no longer distinguishing between the end face and the side surface), and the second welding tooth 5 is a spherical welding tooth.

[0150] For example, on a cross section parallel to the welding surface 21, the outer contour of the second welding tooth 5 is elliptical; on the third direction z, the end face of the second welding tooth 5 away from the welding surface 21 is an arc surface, which smoothly transitions with the side surface of the second welding tooth 5, and thus the entire outer surface of the second welding tooth 5 is part of an ellipsoid (no longer distinguishing between the end face and the side surface), and the second welding tooth 5 is an ellipsoidal welding tooth.

[0151] In the above embodiment, the outer contour of the second welding tooth 5 is a closed conic curve, and decreases in the third direction z in an amplitude rising manner, so that the contact area with the step 220 can be increased during welding, thereby reducing stress concentration on the step 220 and improving the welding quality of the step 220.

[0152] As shown in Figures 7 to 9 , Figure 13 and Figure 16 , according to some embodiments of the present application, optionally, the end surface of the first welding tooth 3 away from the welding surface 21 is a plane, and the end surface of the second welding tooth 5 away from the welding surface 21 is an arc surface. The first welding tooth 3 is a square tooth or a triangular pyramid tooth, and the second welding tooth 5 is a round ball tooth.

[0153] The end surface of the first welding tooth 3 away from the welding surface 21 is the end surface of the free end of the first welding tooth 3 in the third direction z, and the end surface of the second welding tooth 5 away from the welding surface 21 is the end surface of the free end of the second welding tooth 5 in the third direction z.

[0154] The end surface of the first welding tooth 3 away from the welding surface 21 is a plane, and the first welding tooth 3 is a square tooth or a triangular pyramid tooth, which can be pressed on the total thickness part 210 parallel to the surface of the total thickness part 210, and has strong penetration on the total thickness part 210. The end surface of the second welding tooth 5 away from the welding surface 21 is an arc surface, and the second welding tooth 5 is a round ball tooth, which has weak penetration at the step 220.

[0155] In the above embodiment, the end surface of the first welding tooth 3 away from the welding surface 21 is a plane, and the first welding tooth 3 is a square tooth or a triangular pyramid tooth, which causes large stress when pressed on the tab 200 and has strong penetration, so as to improve the welding strength and reduce false welding. The end surface of the second welding tooth 5 away from the welding surface 21 is an arc surface, and the second welding tooth 5 is a round ball tooth, which can reduce stress concentration when pressed on the step 220 and has weak penetration, so as to reduce cracking of the tab 200 and improve the welding quality.

[0156] According to some embodiments of the present application, as shown in Figure 3 , the present application also provides an ultrasonic welding device, which comprises an ultrasonic oscillator 20 and the welding device 10 of any one of the above embodiments, and the welding device 10 is connected to the ultrasonic oscillator 20.

[0157] As shown in Figures 6 to 16As shown, according to some embodiments of the present application, a welding device 10 for ultrasonic welding of the tab 200 of a battery cell is provided, which can be used when the tab 200 is ultrasonic welded with the adapter tab 300. The welding device 10 comprises a welding head 1, which comprises a main body 2 having a welding face 21 provided with a first region 211, a third region 213 and a second region 212 in the first direction x. The welding head 1 further comprises a first welding tooth 3, a second welding tooth 5 and a compensation piece 4. The first welding tooth 3 is located in the first region 211 and protrudes from the welding face 21, and the first welding tooth 3 is a square tooth or a triangular pyramid tooth, and the end face of the first welding tooth 3 away from the welding face 21 is a plane. The first welding tooth 3 is multiple, and is arranged in an array in the first region 211, with the first direction x as the row and the second direction y as the column, and the first welding tooth 3 can be one row and multiple columns or two rows and multiple columns. The compensation piece 4 is located in the second region 212 and protrudes from the welding face 21, and the outer contour of the compensation piece 4 is a rectangle, and the long side is parallel to the second direction y. The end face of the compensation piece 4 away from the welding face 21 is a plane and is parallel to the welding face 21. The compensation piece 4 can be one, two, etc., and when there are two compensation pieces 4, the two compensation pieces 4 are arranged at intervals. The second welding tooth 5 is located in the second region 212 and protrudes from the welding face 21, and the second welding tooth 5 is a spherical tooth, and the second welding tooth 5 is multiple and arranged in an array in the second region 212, with the first direction x as the row and the second direction y as the column, and one row and multiple columns of second welding teeth 5 are arranged on a single compensation piece 4. In the third direction z, the length of the first welding tooth 3 is equal to the sum of the length of the compensation piece 4 and the length of the second welding tooth 5. The welding device 10 reduces the welding times and the required height of the tab 200 by arranging two kinds of welding teeth on one welding face 21, and the welding of the tab 200 and the adapter tab 300 can be completed at one time, reducing the vibration and pulling of the tab 200 caused by multiple welding. The third region 213 is located between the first region 211 and the second region 212, which can compact the tab 200, effectively improve the welding precision and reduce the cracking of the tab 200. The first welding tooth 3 is a square tooth or a triangular pyramid tooth, which can reduce the false welding; the second welding tooth 5 is a spherical tooth, which can reduce the stress at the step 220; and the compensation piece 4 is pressed on the step 220, which can reduce the warping deformation of the tab foil, thereby effectively improving the welding quality. In addition, the structure of the welding head 1 is simple, convenient to process and easy to operate, which can improve the current situation of tab 200 welding and bring progress to the welding work of the tab 200.

[0158] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be replaced equivalently. Such modifications or replacements do not change the essence of the corresponding technical solutions, which should be covered in the scope of the claims and the specification of the present application. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A welding device, characterized in that, The welding device comprises a welding head, the welding head comprising: a main body part having a welding surface, the welding surface being provided with a first region and a second region, the first region being located on one side of the second region in a first direction; a first welding tooth located in the first region and protruding from the welding surface; a second welding tooth located in the second region and protruding from the welding surface; wherein the friction coefficient at the first region is greater than the friction coefficient at the second region.

2. The welding device of claim 1, wherein, The welding head further comprises a compensation member located in the second region and protruding from the welding surface, and the second welding tooth protrudes from the compensation member.

3. The welding device of claim 2, wherein, The compensation member extends in a second direction perpendicular to the first direction.

4. The welding device of claim 2, wherein, The compensation member is provided with a compensation surface, which is an end surface of the compensation member facing away from the welding surface; The compensation surface is a plane and is arranged in parallel with the welding surface.

5. The welding device of claim 2, wherein, In a third direction, the length of the first welding tooth is H1, the length of the second welding tooth is H2, and the length of the compensation member is ΔH; wherein H1=H2+ΔH, and the third direction is perpendicular to the welding surface.

6. The welding device of claim 5, wherein, In the third direction, ΔH ranges from 0.05mm to 0.3mm.

7. The welding device of claim 5, wherein, In the third direction, the length relationship of the first welding tooth and the second welding tooth is: H1=T1×N, H2=T2×N2, N2=N-ΔH; wherein N is the total thickness of the tab to be welded, N2 is the thickness of the tab to be welded at the step, T1 is the friction coefficient at the first region, T2 is the friction coefficient at the second region, the value range of T1 is 0.5 to 0.9, and the value range of T2 is 0.3 to 0.

5.

8. The welding device of claim 7, wherein, The welding surface is further provided with a third region, and in the first direction, the third region is located between the first region and the second region.

9. The welding device of claim 8, wherein, The third region comprises a first sub-region and a second sub-region, the first sub-region is connected to the first region, and the second sub-region is connected to the second region; In the first direction, the length of the third region is A, the length of the first sub-region is D1, and the length of the second sub-region is D2; wherein A=D1+D2, and 0≤D2 / D1≤2.

10. The welding device of claim 9, wherein, In the first direction, A ranges from 1mm to 4mm.

11. The welding device of claim 9, wherein, In the third direction, the length relationship of the compensation member is: wherein Y is the distance of the first tab foil of the tab to be welded from the electrode body in the third direction, and M is the distance of the edge of the first tab foil from the electrode body in the first direction.

12. The welding device of claim 2, wherein, The second welding tooth is a plurality of second welding teeth, and the plurality of second welding teeth are arranged in an array on the compensation member.

13. The welding device of claim 1, wherein, In a direction away from the welding surface, the outer contour of the first welding tooth decreases linearly; In a cross section parallel to the welding surface, the outer contour of the first welding tooth is a convex polygon.

14. The welding device of claim 1, wherein, In a direction away from the welding surface, the outer contour of the second welding tooth gradually decreases, and the decreasing amplitude gradually increases; In a cross section parallel to the welding surface, the outer contour of the second welding tooth is a closed conic curve.

15. The welding device of claim 1, wherein, The first welding tooth is a square tooth or a triangular pyramid tooth, and the end surface of the first welding tooth facing away from the welding surface is a plane; the second welding tooth is a spherical tooth, and the end surface of the second welding tooth facing away from the welding surface is an arc surface.

16. An ultrasonic welding apparatus characterized by comprising: The welding device comprises: An ultrasonic oscillator and a welding device as claimed in any one of claims 1 to 15, the welding device being connected to the ultrasonic oscillator.

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