Tab structure

Abstract

The utility model belongs to the technical field of batteries, and particularly relates to a tab structure which comprises a welding part and an exposed part, the thickness of the welding part is larger than that of the exposed part, and the width of the exposed part is larger than that of the welding part. Compared with the prior art, the welding part has the advantages that the area occupied by the welding part is smaller, a smaller empty foil area can be arranged, more active substance coating positions are provided, the energy density is improved, the overcurrent capacity of the welding part can be kept unchanged by setting the thickness of the welding part to be thicker, and the tab or the current collector can be prevented from being damaged in the tab folding process by setting the exposed part to be wide and thin.

Description

Technical Field

[0001] The utility model belongs to the technical field of batteries, and in particular relates to a pole ear structure. Background Art

[0002] With the rapid development of new energy vehicles and large-scale energy storage industries, people have put forward higher requirements on the energy density and fast charging performance of lithium-ion secondary batteries, which are the "heart" of new energy vehicles. Batteries are also gradually developing towards fast charging, long life, high energy density and high safety. Batteries with high discharge rate, high compaction density and high energy density have emerged. In order to adapt to high discharge rate, more tabs need to be designed to prevent uneven current distribution during high current and cause the temperature to exceed the upper limit.

[0003] However, the existing tabs Figure 1 As shown, the welding portion 1' and the exposed portion 3' of the existing pole ear have the same width, and the pole ear occupies a larger space. The existing winding process fast charging project is to pre-clean the active material coated on the top of the current collector on the battery cell electrode to clean out the empty foil area 2' required for the pole ear welding. The size of the empty foil area 2' is matched with the size of the space occupied by the pole ear welding portion 1'. Therefore, the area of ​​the empty foil area 2' is larger, making it difficult to improve the battery energy density.

[0004] Based on this, it is urgent to invent a tab structure to solve the above-mentioned technical problems. Utility Model Content

[0005] The utility model aims to provide a pole ear structure in view of the deficiencies of the prior art. The pole ear structure is provided with a welding portion with a small width and a thick thickness, so that the area occupied by the pole ear is reduced, the area of ​​the empty foil area is reduced, and the energy density of the battery is improved.

[0006] To achieve the above objectives, this application adopts the following technical solutions:

[0007] A tab structure comprises a welding portion and an exposed portion connected to the welding portion, wherein the width of the exposed portion is greater than the width of the welding portion, and the thickness of the welding portion is greater than the thickness of the exposed portion.

[0008] Specifically, the width of the welding portion is H1 and the thickness is D1, and the width of the exposed portion is H2 and the thickness is D2, and they satisfy the relationship: H1≤2 / 3H2, D1≥1.5D2.

[0009] More specifically, the width of the welding portion is H1 and the thickness is D1, and the width of the exposed portion is H2 and the thickness is D1, and they satisfy the relationship: H1≤1 / 2H2, D1≥2D2.

[0010] Specifically, the welding portion and the exposed portion are an integrally formed structure, and both the welding portion and the exposed portion are arranged in a square shape.

[0011] Specifically, in the thickness direction Z, the welding portion and one side of the exposed portion are on the same plane; the welding portion and the other side of the exposed portion are parallel, and a connecting surface perpendicular to them is formed at their connection.

[0012] Specifically, a chamfer for laser welding process is formed at an edge of one side of the welding portion.

[0013] Specifically, the difference ratio of the cross-sectional area between the welding portion and the exposed portion along the X direction is less than 30%.

[0014] Specifically, it also includes a transition part, through which the welding part is connected to the exposed part, and the transition part includes a first surface coplanar with one surface of the welding part and the exposed part, and a second surface connected to the other surface of the welding part and the exposed part.

[0015] Specifically, the second surface and the first surface form an angle α, and the angle α satisfies the relationship: 90°<α<180°.

[0016] Specifically, the second surface has an A end connected to the exposed portion and a B end connected to the welding portion, and the A end is connected to the B end through a straight line, an arc and a curve structure.

[0017] The beneficial effects of the utility model are as follows: by setting the welding part to have a small width and a thick thickness, the area occupied by the welding part is made smaller, and a smaller empty foil area can be set, providing more coating positions for active materials, and improving energy density. Moreover, since the welding part becomes thicker, the decrease in the flow capacity caused by the reduction in width is compensated, so that the flow capacity of the welding part remains unchanged, and the exposed part is set to be wide and thin so that the strain of the pole ear during bending is smaller, which can prevent the pole ear or the current collector from being damaged during the folding process of the pole ear. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0019] Figure 1 It is a structural schematic diagram of a tab structure in the prior art;

[0020] Among them: 1'-welding part; 2'-empty foil area; 3'-exposed part; 4'-pole piece;

[0021] Figure 2This is one of the structural schematic diagrams of implementation mode 1 of the present utility model;

[0022] Figure 3 This is the second structural diagram of implementation mode 1 of the present utility model;

[0023] Figure 4 for Figure 2 Cross-sectional view along CC section;

[0024] Figure 5 This is a schematic diagram of the structure of implementation mode 3 of the present utility model;

[0025] Figure 6 This is one of the structural schematic diagrams of implementation mode 4 of the present utility model;

[0026] Figure 7 This is the second structural diagram of implementation mode 4 of the present utility model;

[0027] Figure 8 It is one of the partial enlarged views of implementation mode 4;

[0028] Fig. 9 This is the second partial enlarged view of implementation mode 4;

[0029] Fig.10 This is the third partial enlarged view of implementation mode 4;

[0030] Fig.11 This is a schematic diagram of the structure of implementation mode 5 of the present utility model;

[0031] Fig.12 This is a schematic diagram of the structure of implementation mode 6 of the present utility model;

[0032] Among them: 1-welding part; 11-chamfer; 2-transition part; 21-first surface; 22-second surface; 3-exposed part; 4-connecting surface; 5-sealant.

[0033] H1-the width of the welding part; H2-the width of the exposed part; D1-the thickness of the welding part; D2-the thickness of the exposed part; a-the angle between the first surface and the second surface. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0035] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Although the present application is disclosed as above in the form of a preferred embodiment, it is not intended to limit the claims. Any person skilled in the art may make several possible changes and modifications without departing from the concept of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.

[0037] Existing tab structures such as Figure 1 As shown, it is widely used in a large number of batteries. However, with the development of battery technology, the energy density of batteries continues to increase, and high-rate charge and discharge technology is also developing. The battery has higher requirements for the current capacity of the tabs, and a shorter conductive path is required to prevent the battery with high energy density and high resistance from overheating. This requires more tabs to be set for conduction, and setting more tabs will occupy too much area, which limits the improvement of the battery's energy density. Therefore, in order to overcome the shortcomings of the existing tab structure, this application proposes an improved tab structure design. This new design can reduce the area occupied by the tabs and maintain the same current capacity to improve the energy density of the battery. The following is a further detailed description of the utility model in conjunction with the specific implementation method, but the implementation method of the utility model is not limited to this.

[0038] Implementation Method 1

[0039] As shown in Figures 2 and 3, a tab structure includes a welding portion 1 and an exposed portion 3 connected to the welding portion 1.

[0040] The exposed portion 3 is used to make electrical connections with an external circuit, and the welding portion 1 is used to weld the pole ear to the pole piece of the battery and to lead out the current in the current collector of the pole piece. The width of the exposed portion 3 is greater than the width of the welding portion 1, and the thickness of the welding portion 1 is greater than the thickness of the exposed portion 3. Since the exposed portion 3 is set to be wide and thin, the bending of the exposed portion 3 is simpler. After the pole ear is welded to the pole piece, there is a process of folding the pole ear, which requires the pole ear to be bent and collected together, and the bending area is mainly in the exposed portion 3. The exposed portion 3 is set to be thinner so that the exposed portion 3 is easier to bend. The strain received is smaller, and setting the exposed portion 3 wider makes it easier to connect the external circuit to the exposed portion 3, and setting it wider can improve the current carrying capacity of the exposed portion 3; since the position where the welding portion 1 is welded to the electrode piece cannot be coated with active material, setting the welding portion 1 narrower makes the area occupied by the welding portion 1 smaller, and setting the welding portion 1 narrower can provide more active material coating positions, thereby improving the energy density of the battery. In addition, setting the welding portion 1 thicker can ensure the current carrying capacity of the welding portion 1, and at the same time will not decrease due to the narrowing of the welding portion 1.

[0041] Furthermore, the thickness and width of the weld 1 and the exposed portion 3 are limited, wherein the width of the weld 1 is H1 and the thickness is D1, and the width of the exposed portion 3 is H2 and the thickness is D2, and they satisfy the relationship: H1≤2 / 3H2, D1≥1.5D2. This condition ensures that the weld 1 will not be wider than the exposed portion 3, maintains the balance of the overall structure and the beauty of the appearance, and ensures that the weld 1 has sufficient strength in terms of bearing capacity and stability to cope with the challenges of the external environment and the requirements of working conditions. Taken together, these effects ensure the proportion and strength relationship between the weld 1 and the exposed portion 3 to ensure the stability and reliability of the overall structure.

[0042] More preferably, the width of the welding portion 1 is H1 and the thickness is D1, and the width of the exposed portion 3 is H2 and the thickness is D1, and they satisfy the relationship: H1≤1 / 2H2, D1≥2D2. These stricter conditions ensure a more balanced proportional relationship between the welding portion 1 and the exposed portion 3, and provide higher structural strength, thereby enhancing the stability and reliability of the overall structure.

[0043] Preferably, the welding part 1 and the exposed part 3 are an integrally formed structure, which can improve the performance and safety of the battery. The integrally formed structure can reduce the contact resistance inside the battery, improve the conductivity of the battery, and thus improve the charging and discharging efficiency and power density of the battery. Secondly, this structure can reduce the internal gap of the battery, reduce the possibility of vibration or deformation of the battery during use, and thus improve the stability and life of the battery. In addition, the battery pole ear using an integrally formed structure is usually more compact and lightweight, which is conducive to the design and integration of the battery module, while also reducing the overall weight of the battery and improving the energy density of the battery module. Finally, the integrally formed structure can also reduce the manufacturing cost and production cycle because the number of parts and assembly procedures are reduced, simplifying the production process. The welding part 1 and the exposed part 3 are both set to a square shape. This shape makes the processing of the pole ear simpler. In the thickness direction Z, one side of the welding part 1 and the exposed part 3 are on the same plane; the other side of the welding part 1 and the exposed part 3 are parallel, and their connection is formed with a connection surface 4 that is perpendicular to it.

[0044] Implementation Method 2

[0045] like Figure 2 , 4 As shown, the difference from Embodiment 1 is that a chamfer 11 for the laser welding process is formed at one edge of the welding portion 1 of this embodiment. The setting of the chamfer 11 of the tab in the tab laser welding process also has many benefits. First, the chamfer 11 can help achieve more precise welding because it can provide a better contact surface, which helps to align and position the laser welding equipment. This is crucial for the accuracy and stability of the welding process. Secondly, the chamfer 11 can also reduce the residual stress of the welded joint, which helps to reduce the risk of deformation of the parts and can increase the durability and reliability of the welded joint. In addition, the chamfer 11 can also improve the appearance quality of the welded joint, reduce possible welding defects, and improve the overall process efficiency and finished product quality. Therefore, in the tab laser welding process, it is very important to reasonably set the chamfer 11, which can bring many benefits and improve welding quality and production efficiency. In addition, the setting of the chamfer 11 allows the laser welding to be performed below the edge of the pole ear, which reduces the impact range of the laser welding of the pole ear edge. Since lithium is easily deposited when the active material is coated at the weld mark, the active material will not be coated at the weld mark. By setting the chamfer 11, the weld mark generated by the welding of the pole ear and the current collector is below the pole ear, and the weld mark generated by the welding of the pole ear and the current collector has a smaller range, which increases the coating area of ​​the active material and improves the energy density of the battery.

[0046] Preferably, the difference ratio of the cross-sectional area of ​​the welding portion and the exposed portion along the X direction is less than 30%. When the cross-sectional area of ​​each part of the pole ear is controlled within this range, the flow areas of each part of the pole ear are the same or have little difference, and the heating conditions of each part of the pole ear are similar, thereby preventing the pole ear from overheating at a weak position.

[0047] The rest is the same as Implementation 1 and will not be described again here.

[0048] Implementation 3

[0049] like Figure 5 As shown, the difference from Embodiment 1 is that: in order to prevent overheating at the connection between the welding portion 1 and the exposed portion 3, the present embodiment further includes a transition portion 2, the welding portion 1 is connected to the exposed portion 3 through the transition portion 2, the transition portion 2 includes a first surface 21 coplanar with one surface of the welding portion 1 and the exposed portion 3, and a second surface 22 connected to the other surface of the welding portion 1 and the exposed portion 3, so that when the current flows through the welding portion 1, the transition portion 2 and the exposed portion 3, the current is uniform and there will be no overheating due to the fact that the cross-sections of the various parts of the tab do not correspond to each other and the current only flows in the overlapping parts of the cross-sections after welding together, and the flow area is small. Moreover, when the tab is subjected to external force by connecting the welding portion 1 and the exposed portion 3 through the transition portion 2, the stress on the various parts of the tab is small, and the tab is not easily damaged.

[0050] Preferably, the second surface 22 forms an angle α with the first surface 21, and the angle α satisfies the relationship: 90°<α<180°. Within this range, the connection effect of the transition portion 2 is good, ensuring that the transition between the welding portion 1 and the exposed portion 3 is neither too steep nor too gentle, but is a suitable angle, which helps to improve the strength and stability of the structure, while reducing the possibility of stress concentration and fatigue failure, and the current dispersion is not prone to overheating.

[0051] The rest is the same as Implementation 1 and will not be described again here.

[0052] Implementation 4

[0053] like Figure 6-10As shown, the difference from Embodiment 3 is that the second surface 22 of this embodiment has an A end connected to the exposed portion 3 and a B end connected to the welding portion 1, and the A end is connected to the B end through a straight line, an arc and a curve structure. In order to adapt to the battery process and the difficulty of manufacturing the pole ear, the second surface 22 is set to different structures. When the second surface 22 is set to a straight line, the manufacturing process of the pole ear is relatively simple, but the transition with the welding portion 1 and the exposed portion 3 is not smooth enough, especially when the pole ear is designed to be shorter, the space occupied by the transition portion 2 is small. The second surface 22 is set to a straight line structure, which easily leads to stress concentration at the transition between the transition portion 2 and the welding portion 1 and the exposed portion 3. Because there is not enough space for a smooth transition, the force concentration of the component is increased, which may lead to insufficient strength. Or it is prone to cracks, and is not suitable for batteries with small space in the transition portion 2. The second surface 22 is set to a curved structure to connect the welding portion 1 and the exposed portion 3. Since the transition is smooth and the curve can better disperse the stress, it brings better structural strength and is more beautiful in appearance. However, the curved structure has a complex geometric shape and curvature, so it requires precise design and processing technology, and the processing cycle is long and the manufacturing cost is high. The cost of setting the second surface 22 to a circular arc structure is lower than that of a curved structure, and the transition effect is better than that of a straight line structure. The second surface 22 can also be set to a stepped structure. The stepped structure can be formed by welding multiple steps. When different types of pole ears need to be manufactured, different steps can be selected for welding to adapt to different types of batteries.

[0054] The structures of the two sides of the width of the transition portion 2 are set as: one side is an arc structure, and the other side is a straight structure. The advantage of this design is that it combines the advantages of the two structures. It has the simplicity and easy production of the straight structure, and the arc structure can provide a smoother transition, which helps to reduce stress concentration and the generation of cracks.

[0055] The rest is the same as Implementation 3 and will not be repeated here.

[0056] Implementation method 5

[0057] like Fig.11 As shown, the difference from Embodiment 4 is that the width of the welding portion 1 of this embodiment is set to gradually decrease from the transition portion 2 to the welding portion 1 along the Y direction. Since the heat of the tab increases with the convergence of current, the degree of convergence of current at each position of the tab welding portion 1 is different. The current continuously converges from the welding portion 1 to the transition portion 2. Therefore, the current is maximum at the welding portion 1 close to the transition portion 2 and small at the position far from the transition portion 2. Therefore, the width of the welding portion 1 can be set to gradually decrease from the transition portion 2 to the welding portion 1 along the Y direction, so that the current size and the width of the welding portion 1 are matched, the area occupied by the welding portion 1 can be reduced, the coating area of ​​the active material can be increased, and the energy density of the battery can be increased.

[0058] The rest is the same as Implementation 4 and will not be repeated here.

[0059] Implementation 6

[0060] like Fig.12 As shown, the difference from Embodiment 4 is that the two sides of the width of the transition portion 2 of this embodiment are set as an arc structure, and the sealant 5 is set on the transition portion 2 of the pole ear, and the width of the sealant 5 matches the transition portion 2. Since the width of the transition portion 2 is smaller than that of the exposed portion 3, the use of the sealant 5 can be reduced, and the two sides of the transition portion 2 are set as an arc structure. The width of the end connected to the welding portion 1 is small and the width of the end connected to the exposed portion 3 is large. For this design, the battery shell also needs to be adjusted accordingly, showing a shape with one end large and the other end small. This design helps to effectively limit the transition portion 2 in a certain direction. In the other direction, the limit is also achieved due to welding with the current collector, which increases the stability and rigidity of the pole ear, making it more able to resist the influence of external forces and vibrations, and improves the stability of the overall structure of the battery.

[0061] The rest is the same as Implementation 4 and will not be repeated here.

[0062] The above are only preferred implementations of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A tab structure, characterized in that: It comprises a welding portion (1) and an exposed portion (3) connected to the welding portion (1), wherein the width of the exposed portion (3) is greater than the width of the welding portion (1), and the thickness of the welding portion (1) is greater than the thickness of the exposed portion (3).

2. The tab structure according to claim 1, characterized in that: The width of the welding portion (1) is H1 and the thickness is D1, and the width of the exposed portion (3) is H2 and the thickness is D2, and they satisfy the relationship: H1≤2 / 3H2, D1≥1.5D2.

3. The tab structure according to claim 2, characterized in that: The width of the welding portion (1) is H1 and the thickness is D1, and the width of the exposed portion (3) is H2 and the thickness is D1, and they satisfy the relationship: H1≤1 / 2H2, D1≥2D2.

4. The tab structure according to claim 1, characterized in that: The welding portion (1) and the exposed portion (3) are an integrally formed structure, and the welding portion (1) and the exposed portion (3) are both arranged in a square shape.

5. The tab structure according to claim 4, characterized in that: In the thickness direction Z, the welding portion (1) and one side of the exposed portion (3) are on the same plane; the other sides of the welding portion (1) and the exposed portion (3) are parallel, and a connecting surface (4) perpendicularly connected thereto is formed at their connection.

6. The tab structure according to claim 4, characterized in that: A chamfer (11) for laser welding is formed at one edge of the welding portion (1).

7. The tab structure according to claim 1, characterized in that: The difference ratio of the cross-sectional area of ​​the welding portion (1) and the exposed portion (3) along the X direction is less than 30%.

8. The tab structure according to claim 1, characterized in that: It also comprises a transition portion (2), the welding portion (1) being connected to the exposed portion (3) via the transition portion (2), the transition portion (2) comprising a first surface (21) coplanar with one surface of the welding portion (1) and the exposed portion (3), and a second surface (22) connected to the other surface of the welding portion (1) and the exposed portion (3).

9. The tab structure according to claim 8, characterized in that: The second surface (22) and the first surface (21) form an angle α, and the angle α satisfies the relationship: 90°<α<180°.

10. The tab structure according to claim 8, characterized in that: The second surface (22) has an A end connected to the exposed portion (3) and a B end connected to the welding portion (1), and the A end is connected to the B end via a straight line, an arc, or a curve structure.

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