Aluminum bar structure and battery pack

Abstract

The utility model discloses an aluminum row structure and a battery pack, the aluminum row comprises a first surface and a second surface which are opposite to each other, and the first surface is used for being electrically connected with a pole of a battery; the aluminum bar structure is provided with a welding hole penetrating through the first face and the second face, the diameter of the welding hole on the first face is a first diameter, the diameter of the welding hole on the second face is a second diameter, and the first diameter is smaller than the second diameter. Compared with the prior art, the wall of the welding hole is not prone to collapse, and the welding seam performance is better.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to an aluminum busbar structure and a battery pack. Background Technology

[0002] Battery packs and battery modules typically include multiple individual cells, which are commonly connected in series, parallel, or both via aluminum busbars. Welding is one of the main methods of connecting the aluminum busbar to the terminals of the individual cells. Specifically, welding holes are made in the aluminum busbar to expose part of the terminal, and the walls of the welding holes are melted by laser. After cooling, the aluminum busbar and the terminal are welded together.

[0003] During the process of local melting and solidification of the existing aluminum busbar, there is a significant flow of aluminum busbar material. This leads to uncertainty in the specific shape of the weld. Furthermore, the molten metal flowing to the surface of the pole forms oxide inclusions when it comes into contact with air, which greatly degrades the welding effect of the weld. Utility Model Content

[0004] One objective of this invention is to provide an aluminum busbar structure and a battery pack, which aims to solve the technical problem of poor weld quality formed by aluminum busbar welding.

[0005] To achieve the above objectives, the present invention provides an aluminum busbar structure, which includes a first surface and a second surface opposite to each other. The first surface is used for electrical connection with the terminal post of a battery. The aluminum busbar structure is provided with a welding hole penetrating through the first surface and the second surface. The diameter of the welding hole on the first surface is a first diameter, and the diameter of the welding hole on the second surface is a second diameter. The first diameter is smaller than the second diameter.

[0006] In some embodiments, the wall of the welding hole is inclined relative to the axial direction of the welding hole.

[0007] In some embodiments, the angle between the wall of the welding hole and the first surface is α, where 40°≤α≤80°.

[0008] In some embodiments, the wall of the welding hole is stepped.

[0009] In some embodiments, the aluminum busbar structure includes a first row, a second row, and a third row. The first row is disposed at both ends of the second row, and the first and second rows are connected through the third row. Welding holes are disposed on the first row. The second and third rows together form a clearance space, and the opening direction of the clearance space is directed toward the battery.

[0010] In some embodiments, the second row of bodies is connected to the third row of bodies by an arc; and / or the first row of bodies is connected to the third row of bodies by an arc.

[0011] In some embodiments, a through positioning hole is provided on the second row body, and the axis of the positioning hole is perpendicular to the first surface.

[0012] In some embodiments, the thickness of the aluminum busbar structure is L in the axial direction of the welding hole, where 2mm ≤ L ≤ 3mm.

[0013] In some embodiments, the first diameter is D, where 15mm ≤ D ≤ 20mm.

[0014] To achieve the above objectives, the present invention provides a solution: a battery pack comprising multiple individual cells and an aluminum busbar structure as described above, wherein adjacent individual cells are electrically connected through the aluminum busbar structure.

[0015] The beneficial effects of this utility model are as follows:

[0016] The aluminum busbar includes a first surface that contacts the battery terminal and a second surface opposite the first surface. A welding hole penetrates both surfaces. The size of the welding hole on the first surface is smaller than that on the second surface; that is, the cross-sectional size of the welding hole increases from the first surface to the second surface. When the wall of the welding hole is melted and becomes fluid, the inclined wall provides stability similar to a dam, making it difficult for the molten metal to flow significantly before solidification. Therefore, throughout the welding process, the risk of oxidation at the connection surface between the terminal and the aluminum busbar is low, and the weld morphology is stable.

[0017] Compared with the prior art, on the one hand, the shape of the aluminum busbar weld seam of this utility model is basically consistent with the shape of the weld hole wall before welding, and the weld seam morphology can be predicted and is easy to control; on the other hand, the connection surface between the pole and the aluminum busbar is the contact surface during assembly, which greatly reduces the oxidation of the weld seam. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of aluminum busbars in existing technology;

[0020] Figure 2 It is along Figure 1 Schematic diagram of the cross section of line AA;

[0021] Figure 3 This is a schematic diagram of the overall structure of the aluminum busbar structure provided in one embodiment of the present invention;

[0022] Figure 4 It is along Figure 3 Schematic diagram of the cross section of the middle BB line;

[0023] Figure 5 This is a schematic diagram showing the relationship between the aluminum busbar structure and the single battery cell provided in one embodiment of the present invention;

[0024] Figure 6 This is a cross-sectional schematic diagram of an aluminum busbar structure provided in one embodiment of the present invention;

[0025] Figure 7 This is a schematic diagram of the overall structure of the aluminum busbar structure provided in one embodiment of the present invention;

[0026] Figure 8 This is a schematic diagram of the overall structure of the aluminum busbar structure provided in one embodiment of the present invention;

[0027] Figure 9 This is a schematic diagram of the overall structure of a battery pack provided in one embodiment of the present invention.

[0028] Explanation of icon numbers:

[0029] 10. Aluminum busbar structure; 1a. First side; 1b. Second side; 11. First row body; 111. Welding hole; 112. Thermocouple groove; 12. Second row body; 121. Positioning hole; 13. Third row body; 14. Clearance space; 20. Single cell; 21. Battery body; 22. Terminal post. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] Please see Figures 1 to 5 As shown, Figure 1 This is a schematic diagram of the overall structure of aluminum busbars in existing technology; Figure 2 It is along Figure 1 Schematic diagram of the cross section of line AA; Figure 3 This is a schematic diagram of the overall structure of the aluminum busbar structure 10 provided in one embodiment of the present invention; Figure 4 It is along Figure 3 Schematic diagram of the cross section of the middle BB line;

[0032] Figure 5 This is a schematic diagram showing the relationship between the aluminum busbar structure and the single battery cell provided in one embodiment of this utility model.

[0033] This utility model embodiment provides an aluminum busbar structure 10, which includes a first surface 1a and a second surface 1b opposite to each other. The first surface 1a is used for electrical connection with the terminal post 22 of the battery. The aluminum busbar structure 10 is provided with a welding hole 111 penetrating through the first surface 1a and the second surface 1b. The diameter of the welding hole 111 on the first surface 1a is a first diameter, and the diameter of the welding hole 111 on the second surface 1b is a second diameter. The first diameter is smaller than the second diameter.

[0034] Currently, the welding of aluminum busbars and pole posts 22 is commonly achieved by laser welding. Unlike brazing, which relies on the filling of filler metal to create the weld, the formation of the laser weld depends on the cladding of the workpiece material itself. Therefore, the entire laser welding process is usually accompanied by the overflow of molten metal and the collapse of the wall of the welding hole 111.

[0035] The aluminum busbar structure 10 provided by this utility model, at the welding angle, that is, when the aluminum busbar structure 10 is located above the battery, the cross-sectional area of ​​the welding hole 111 decreases from top to bottom, and the cross-sectional shape of the hole wall of the welding hole 111 on the plane passing through its axis is similar to that of a dam. From a microscopic point of view, the upper hole wall is obstructed by the lower hole wall during the downward flow, making it difficult to make significant displacement in the short time before solidification; from a macroscopic point of view, the hole wall of the welding hole 111 of the aluminum busbar structure 10 forms a weld after melting and solidification, and part of the aluminum busbar structure 10 on the first surface 1a is bonded to the electrode post 22, realizing the fixed connection between the aluminum busbar structure 10 and the battery.

[0036] Compared with the prior art, on the one hand, the shape of the aluminum busbar structure 10 in this embodiment does not change significantly before and after welding. The shape of the welding hole 111 before welding is the same as the shape of the weld after welding, so the shape of the weld is stable and controllable. On the other hand, in the prior art, the hole wall of the welding hole 111 will be exposed to air at high temperature during the melting and collapse process, resulting in severe oxide inclusions. As the collapse continues, this oxide scale is rolled into the lower end of the weld, and the inclusions are retained between the weld and the pole post 22. These inclusions will seriously degrade the performance of the weld. In this embodiment, it is only necessary to clean the area where the first surface 1a contacts the pole post 22. During the subsequent welding process, the area to be connected will remain in contact throughout, making it difficult for air to penetrate. The risk of oxidation of the connection surface is small, and welding quality similar to gas shielded welding can be achieved even when welding in an air environment.

[0037] It should be noted that most weld holes 111 have a circular cross-section perpendicular to their axis. For a small number of irregularly shaped holes, the diameter here should be understood as the longest achievable cross-sectional length within the cross-sectional shape. For example, in one technical solution, the weld hole 111 has a square edge shape on the first surface 1a, then the length of the diagonal of the square is the first diameter; as another example, in another technical solution, the weld hole 111 has an elliptical edge shape on the second surface 1b, then the length of the major axis of the ellipse is the second diameter.

[0038] In some embodiments, the wall of the welding hole 111 is inclined relative to the axial direction of the welding hole 111.

[0039] This embodiment provides a specific hole wall structure design. The inclined hole wall facilitates processing. When drilling the welding hole 111, a tapered drill bit or a frustum drill bit can be used to form it in one step, making the welding hole 111 in this embodiment suitable for mass production.

[0040] Furthermore, the angle between the wall of the welding hole 111 and the first surface 1a is α, where 40°≤α≤80°, and α is preferably 60°.

[0041] In actual welding processes, an excessively large angle α can cause the material below to be unable to support the material above, resulting in slippage before the molten metal solidifies. Conversely, an excessively small angle α results in an excessively large projected area of ​​the weld hole 111 wall on the electrode post 22, increasing the required welding laser power. Even if the welding equipment is adjusted to provide sufficient heat source power, overheating of the weld can still occur, further degrading weld performance. Therefore, in some embodiments of this invention, the angle α between the weld hole 111 wall and the first surface 1a is limited to 40°≤α≤80° to simultaneously meet the requirements of preventing weld slippage and facilitating processing.

[0042] Please see Figure 6 As shown, Figure 6 This is a cross-sectional schematic diagram of an aluminum busbar structure 10 provided in one embodiment of the present invention. In some embodiments, the wall of the welding hole 111 is stepped.

[0043] In the processing of certain large-diameter welding holes 111, using a conical drill bit for one-time forming may present significant processing difficulties. Therefore, according to the general approach in this field, a step-by-step drilling process using straight drill bits of increasing size along the axis can be adopted to form stepped holes before re-drilling into conical holes. However, for the technical effect required by this invention, the final re-drilling step is unnecessary, yet the effect of optimizing weld performance can be significantly achieved. Therefore, making the hole wall of the welding hole 111 stepped can, in some situations, especially when the diameter of the welding hole 111 is large or when the aluminum busbar contains alloying elements, reduce processing costs to a certain extent.

[0044] Please see Figure 7 As shown, Figure 7 This is a schematic diagram of the overall structure of the aluminum busbar structure 10 provided in one embodiment of the present invention. In some embodiments, the aluminum busbar structure 10 includes a first busbar 11, a second busbar 12, and a third busbar 13. The first busbar 11 is disposed at both ends of the second busbar 12, and the first busbar 11 and the second busbar 12 are connected through the third busbar 13. Welding holes 111 are disposed on the first busbar 11. The second busbar 12 and the third busbar 13 together form a clearance space 14, and the opening direction of the clearance space 14 is directed toward the battery.

[0045] During operation, batteries inevitably experience heat generation and even expansion. In existing battery pack structures, the connection strength between the battery and the aluminum busbar is relatively low. Therefore, when the battery expands beyond the limit of the aluminum busbar, the connection between the terminal post 22 and the aluminum busbar will break. However, in this embodiment, the connection between the aluminum busbar structure 10 and the battery is more stable. When the battery expands, the aluminum busbar structure 10 still maintains its connection with the battery, which may lead to compression between the batteries. In this embodiment, the second row 12 and the third row 13 together form a clearance space 14. When adjacent batteries come into contact and continue to expand, the second row 12 and the third row 13 are flattened to compensate for the increased distance between the two welding holes 111 caused by the battery expansion.

[0046] Furthermore, the second row of bodies 12 and the third row of bodies 13 are connected by an arc; and / or the first row of bodies 11 and the third row of bodies 13 are connected by an arc.

[0047] During the unfolding and repositioning process of the aluminum busbar structure 10, the stress concentration phenomenon is not obvious, and the aluminum busbar structure 10 is less likely to be torn. Under extreme conditions, the aluminum busbar structure 10 in this embodiment can still perform its conductive function.

[0048] Furthermore, the second row of body 12 is provided with a through positioning hole 121, the axis of which is perpendicular to the first surface 1a. Preferably, there are two positioning holes 121.

[0049] The positioning hole 121 facilitates the positioning of the aluminum busbar structure 10 with the external structure, and also facilitates the clamping of the aluminum busbar structure 10 during the assembly process.

[0050] Optionally, a thermocouple groove 112 may also be provided on the first row of bodies 11.

[0051] Because the aluminum busbar structure 10 is welded to the electrode post 22, measuring the temperature of the aluminum busbar structure 10 can directly reflect the temperature of the battery. The thermocouple placed in the thermocouple groove 112 can effectively monitor whether the battery has thermal runaway.

[0052] Optional, please refer to Figure 8 As shown, Figure 8 Another structure for the clearance space 14 is shown. In some embodiments, the two first row bodies 11 are connected by an arc-shaped arch bridge. When the two first row bodies 11 move away from each other due to the expansion of the battery, the arch bridge flattens out, achieving the same clearance effect.

[0053] Please see Figure 4 As shown, in some embodiments, the thickness of the aluminum busbar structure 10 is L in the axial direction of the welding hole 111, where 2mm≤L≤3mm.

[0054] The greater the thickness of the aluminum busbar structure 10, the stronger its current-carrying capacity, but the greater the difficulty of welding it. In this embodiment, the thickness L of the aluminum busbar structure 10 is limited to 2mm≤L≤3mm, ensuring the current-carrying capacity while guaranteeing that the aluminum busbar can be fully welded.

[0055] In some embodiments, the first diameter is D, where 15mm ≤ D ≤ 20mm.

[0056] If the first diameter is too large, it will increase the weld length and prolong the welding time of each aluminum busbar structure 10. If the first diameter is too small, it will lead to insufficient weld strength. Therefore, in this embodiment, the first diameter D is limited to 15mm≤D≤20mm, which takes into account both the weld strength and the processing time of each aluminum busbar structure 10.

[0057] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, it is also expected that ranges of 60 to 110 and 80 to 120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5.

[0058] In this application, unless otherwise stated, the numerical range "a to b" is a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 and 5" have been listed herein, and "0 to 5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0059] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0060] Please see Figure 9 As shown, Figure 9 This is a schematic diagram of the overall structure of a battery pack provided in one embodiment of the present invention. The present invention also discloses a battery pack comprising a plurality of individual cells 20 and an aluminum busbar structure 10 as disclosed in any of the above embodiments, wherein adjacent individual cells 20 are electrically connected through the aluminum busbar structure 10.

[0061] It should be noted that the improvements in this application only involve the welding of the single cell 20 to the aluminum busbar structure 10. Therefore, for clarity, the single cell 20 is simply illustrated in the drawings as an electrically connected battery body 21 and terminal post 22. The single cell 20 may include lithium-ion secondary single cells, lithium-ion primary single cells, lithium-sulfur single cells, sodium-lithium-ion single cells, sodium-ion single cells, or magnesium-ion single cells, etc., and some embodiments of this application are not limited to these. The single cell 20 also includes electrode components and electrolyte. The electrode components include a positive electrode, a negative electrode, and a separator. The single cell 20 mainly relies on the movement of metal ions between the positive and negative electrode to operate. The positive electrode includes a positive current collector and a positive active material layer, the positive active material layer being coated on the surface of the positive current collector; the positive current collector includes a positive electrode coating area and a positive electrode tab connected to the positive electrode coating area, the positive electrode coating area being coated with the positive active material layer, and the positive electrode tab not being coated with the positive active material layer. Taking a lithium-ion single-cell battery as an example, the positive electrode current collector can be made of aluminum, and the positive electrode active material layer includes positive electrode active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, with the negative electrode active material layer coated on the surface of the negative electrode current collector. The negative electrode current collector includes a negative electrode coating area and a negative electrode tab connected to the negative electrode coating area. The negative electrode coating area is coated with the negative electrode active material layer, while the negative electrode tab is not coated with the negative electrode active material layer. The negative electrode current collector can be made of copper, and the negative electrode active material layer includes negative electrode active material, which can be carbon or silicon, etc. The separator can be made of polypropylene (PP) or polyethylene (PE), etc. In the battery pack, there can be multiple single-cell batteries 20, which can be connected in series, parallel, or mixed. Mixed connection means that multiple single-cell batteries 20 are connected in both series and parallel. Multiple individual batteries 20 can be directly connected in series, parallel, or in a mixed manner, and then the whole composed of multiple individual batteries 20 is housed in the box; of course, the battery pack can also be composed of multiple individual batteries 20 first connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules are connected in series, parallel, or in a mixed manner to form a whole, and housed in the box.

[0062] The aluminum busbar structure 10 serves as the current-carrying component of the battery pack, through which multiple individual cells 20 are electrically connected to each other, enabling series, parallel, or mixed connection of the individual cells 20. Each individual cell 20 can be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The individual cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0063] Because the aluminum busbar structure 10 used in this embodiment is the same as the aluminum busbar structure 10 disclosed in the above embodiments, the battery pack of this embodiment has the same advantages as the aluminum busbar assembly of the above embodiments. Specifically, in the battery pack of this embodiment, the weld performance of the connection between the individual battery cell 20 and the aluminum busbar structure 10 is better. It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this utility model are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicator will also change accordingly.

[0064] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0065] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0066] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the design concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. An aluminum busbar structure, characterized in that, include: The first and second sides are opposite to each other, and the first side is used for electrical connection with the battery terminals; The aluminum busbar structure is provided with welding holes penetrating the first surface and the second surface. The diameter of the welding hole on the first surface is a first diameter, and the diameter of the welding hole on the second surface is a second diameter. The first diameter is smaller than the second diameter.

2. The aluminum busbar structure according to claim 1, characterized in that, The wall of the welding hole is inclined relative to the axial direction of the welding hole.

3. The aluminum busbar structure according to claim 2, characterized in that, The angle between the wall of the welding hole and the first surface is α, where 40°≤α≤80°.

4. The aluminum busbar structure according to claim 1, characterized in that, The wall of the welding hole is stepped.

5. The aluminum busbar structure according to claim 1, characterized in that, The aluminum busbar structure includes a first busbar, a second busbar, and a third busbar. The first busbar is located at both ends of the second busbar, and the first busbar and the second busbar are connected through the third busbar. The welding hole is located on the first busbar. The second busbar and the third busbar together form a clearance space, and the opening direction of the clearance space is directed toward the battery.

6. The aluminum busbar structure according to claim 5, characterized in that, The second row of bodies and the third row of bodies are connected by an arc; and / or The first row of bodies and the third row of bodies are connected by an arc.

7. The aluminum busbar structure according to claim 5, characterized in that, The second row of bodies has a through positioning hole, and the axis of the positioning hole is perpendicular to the first surface.

8. The aluminum busbar structure according to any one of claims 1-7, characterized in that, In the axial direction of the welding hole, the thickness of the aluminum busbar structure is L, where 2mm ≤ L ≤ 3mm.

9. The aluminum busbar structure according to any one of claims 1-7, characterized in that, The first diameter is D, where 15mm ≤ D ≤ 20mm.

10. A battery pack, characterized in that, include: The aluminum busbar structure and multiple individual cells according to any one of claims 1-9, wherein adjacent individual cells are electrically connected through the aluminum busbar structure.

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