Composite pole, negative electrode assembly and cylindrical battery cell
By using copper-aluminum composite electrodes and laser penetration welding technology, the problem of connecting the electrodes of aluminum-cased cylindrical cells to the current collector was solved, enabling large-area welding and improving battery performance and production efficiency.
Patent Information
- Application Number
- CN202423107821.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-17
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2034-12-17
AI Technical Summary
The existing aluminum-cased cylindrical battery cell has difficulty in achieving effective welding between the terminals and current collectors, and laser penetration welding of composite terminals is challenging, affecting battery performance and availability.
The composite electrode is made of copper-aluminum composite material. The exposed part is made of aluminum and the inside is made of copper. The negative electrode current collector is connected by laser penetration welding process. The structure is optimized to ensure that the welding area is made of copper and to avoid the influence of aluminum.
Large-area welding was achieved, reducing module welding costs, simplifying equipment, improving current carrying capacity and welding yield, and increasing battery energy and power density.
Smart Images
Figure CN223898557U_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of battery technology, specifically to a composite electrode post, a negative electrode assembly, and a cylindrical battery cell. Background Technology
[0002] Electric vertical takeoff and landing (EVTOL) aircraft typically use cylindrical batteries (lithium-ion batteries) as their power source. This application demands significantly higher energy and power density from these batteries compared to traditional power batteries. Aluminum-cased cylindrical cells offer significant advantages in increasing the energy and power density of battery packs compared to the nickel-plated steel casings used in traditional cylindrical cells. These advantages stem from the aluminum casing material's lighter weight, higher thermal and electrical conductivity, and better processability.
[0003] In the structural design of aluminum-cased cylindrical battery cells, the aluminum casing must serve as the positive electrode to prevent electrochemical corrosion, while the terminal block serves as the negative electrode, typically made of copper. When assembling battery cells into modules, they need to be connected in series, requiring a busbar to connect the negative electrode of one cell to the positive electrode of the next. Therefore, the busbar needs to be welded to both the aluminum casing and the copper terminal block, but the different materials of the two materials hinder the welding process. One solution to this problem is to use a copper-aluminum composite material for the terminal block, where the exposed portion of the negative terminal block is aluminum, and the portion inside the cell is copper.
[0004] Meanwhile, a major factor limiting the overcurrent capacity of cylindrical battery cells is the connection process of different components in the battery structure. Different connection processes result in different effective connection areas, and the size of the effective connection area directly affects the local heat generation at that connection location under high current. Currently, the connection between the terminals and current collectors / handles of cylindrical battery cells is mostly achieved through resistance spot welding or ultrasonic welding. These processes require a welding needle to pass through the center hole of the core to reach the working plane and complete the welding. However, due to the limitation of the diameter of the core's center hole, the size of the welding needle is limited, thus limiting the effective connection area formed by this process. To solve this problem, the current solution is to use laser penetration welding to weld the current collectors and terminals, thereby bypassing the limitation of the core's center hole.
[0005] To improve the performance and usability of aluminum-cased cylindrical cells, both of the above designs need to be used simultaneously: using copper-aluminum composite electrodes and laser penetration welding. However, the double-layer structure of the composite electrodes greatly increases the difficulty of laser penetration welding, making it almost impossible to manufacture. Utility Model Content
[0006] This application provides a composite electrode post, a negative electrode assembly, and a cylindrical battery cell.
[0007] The objectives of this application include: 1. Using copper-aluminum composite materials to fabricate composite poles, and through reasonable structural design and process coordination, making the part of the composite pole inside the battery cell used to connect the negative current collector copper, while the exposed part of the composite pole for bus welding is made of aluminum; 2. By improving the structural design of the composite pole, making the entire welding area copper, thereby making it feasible to use a laser to penetrate the welding position of the composite pole from the outside of the battery cell to weld the copper negative current collector.
[0008] In a first aspect, this application proposes a composite pole, comprising:
[0009] The electrode body includes an outer electrode layer made of aluminum and an inner electrode layer made of copper.
[0010] The outer blind hole extends from the outer side of the pole body to the inner side, and its depth is greater than that of the outer layer of the pole.
[0011] The inner blind hole extends from the inside to the outside of the pole body, and its depth is less than that of the inner layer of the pole.
[0012] The filler plug, a cylindrical aluminum material, is placed inside the outer blind hole and welded to the pole body.
[0013] In some alternative embodiments, the thickness of the filler plug is equal to the depth of the outer blind hole, or 0.1 mm to 0.5 mm less than the depth of the outer blind hole.
[0014] In some alternative embodiments, the longitudinal section of the pole post is I-shaped, and the side of the pole post has an annular groove.
[0015] In some alternative embodiments, the distance H between the bottom of the outer blind hole and the bottom of the inner blind hole is between 0.4 mm and 2 mm.
[0016] In some alternative embodiments, the surface of the outer blind hole is roughened or covered with a layer of black light-absorbing material.
[0017] Secondly, this application proposes a negative electrode component, comprising:
[0018] The substrate has a central through-hole;
[0019] The composite pole as described in the first aspect is inserted through the central through hole;
[0020] An insulating sealing gasket is disposed between the composite pole and the substrate;
[0021] The negative electrode current collector is made of copper and has a boss that extends into the inner blind hole of the composite electrode post and is welded and interconnected with the inner electrode post component of the composite electrode post.
[0022] In some alternative embodiments, the height of the boss is equal to the depth of the inner blind hole, or is 0.1 mm to 0.5 mm greater than the depth of the inner blind hole.
[0023] In some alternative embodiments, the other side of the negative current collector has a recess corresponding to the boss, and a copper pad is disposed in the recess.
[0024] In some optional embodiments, the total thickness h from the bottom surface of the copper pad to the top surface of the boss is between 0.4 mm and 2 mm, the distance H between the bottom of the outer blind hole of the pole body and the bottom of the inner blind hole of the pole body is between 0.4 mm and 2 mm, and the ratio of H to h is between 0.6 and 1.4.
[0025] Thirdly, this application proposes a cylindrical battery cell, comprising: a negative electrode assembly as described in the second aspect.
[0026] The present application proposes a battery, and the technical effects achieved through the above solution include:
[0027] 1. This application uses copper-aluminum composite material to form a composite pole. Through reasonable design, the part of the composite pole inside the cell (i.e., the inner layer of the pole) is made of copper, while the part of the composite pole exposed for busbar welding area (i.e., the outer layer of the pole) is made of aluminum. As a result, the busbar does not need to be welded to copper, so the busbar can be made of pure aluminum, which greatly reduces the material and equipment costs of module welding.
[0028] 2. By improving the structural design of the composite electrode post, the depth of the outer blind hole is made greater than that of the outer electrode post (i.e., penetrating the outer electrode post), so that the area used for laser welding (i.e. the outer blind hole) is made entirely of copper instead of aluminum. This allows the composite electrode post (copper inner electrode post) and the negative current collector (copper) to be welded from the outside of the cell using a laser.
[0029] This eliminates the limitation of the welding needle, so the effective welding area is no longer limited by the diameter of the core center hole, thus allowing for a larger effective welding area, reducing the internal resistance of the battery cell, and increasing the current it can withstand.
[0030] Furthermore, by avoiding the use of welding pins, the center hole hot-hole process is not required during winding, and the heat and wear of welding pins need not be considered, which simplifies the equipment and improves efficiency in automated and continuous production.
[0031] 3. In some optional embodiments, this application can further improve the welding effect and yield by optimizing the material thickness of the welding area and increasing the parameter window of the welding process. Attached Figure Description
[0032] Other features, objects, and advantages of this disclosure will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:
[0033] Figure 1 This is a cross-sectional structural schematic diagram of an embodiment of the composite pole according to this application;
[0034] Figure 2 This is a cross-sectional structural schematic diagram of an embodiment of the negative electrode component according to this application;
[0035] Figure 3 This is a three-dimensional structural schematic diagram of an embodiment of a cylindrical battery cell according to this application;
[0036] Figure 4 This is a cross-sectional structural schematic diagram of an embodiment of a cylindrical battery cell according to this application;
[0037] Figure 5 This is a schematic diagram of the assembly process of an embodiment of the negative electrode component according to this application.
[0038] Explanation of reference numerals / symbols in the attached diagram:
[0039] 10-Composite pole; 11-Outer pole component; 12-Inner pole component; 13-Outer blind hole; 14-Inner blind hole; 15-Filling plug; 16-Annular groove; 20-Base; 30-Insulating sealing gasket; 40-Negative current collector; 50-Copper pad; 60-Shell; 70-Core; 80-Positive current collector; 90-Cover plate. Detailed Implementation
[0040] The specific embodiments of this application will be described below with reference to the accompanying drawings and examples. Those skilled in the art can easily understand the technical problems solved by this application and the resulting technical effects through the content described herein. It is understood that the specific embodiments described herein are merely illustrative of the relevant invention and are not intended to limit the invention. Furthermore, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.
[0041] It should be readily understood that the meanings of “on,” “above,” and “on top of” in this application should be interpreted in the broadest sense, such that “on” means not only “directly on something,” but also “on something” including intermediate components or layers existing between the two.
[0042] Furthermore, for ease of description, spatial relative terms such as “below,” “under,” “lower,” “above,” and “upper” may be used herein to describe the relationship of one element or component to another element or component shown in the accompanying drawings. In addition to the orientations described in the figures, spatial relative terms are also intended to cover different orientations of the device during use or operation. The device may be oriented in other ways (rotated 90° or otherwise), and the spatial relative descriptive terms used herein may be interpreted accordingly.
[0043] It should be noted that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading of the contents described in the specification. They are not intended to limit the scope of this application and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives of this application, should still fall within the scope of the technical content disclosed in this application. Furthermore, terms such as "above," "first," "second," and "a" used in this specification are merely for clarity of description and are not intended to limit the scope of this application. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this application's implementation.
[0044] Furthermore, where there is no conflict, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0045] refer to Figure 1 The diagram shows a cross-sectional structure of one embodiment of the composite pole of this application. Figure 1 As shown, the composite terminal of this application is suitable as a terminal for a cylindrical battery cell, including:
[0046] The electrode body is made of bimetallic composite material and consists of two layers, including an outer electrode layer 11 made of aluminum and an inner electrode layer 12 made of copper. The two can be joined together by welding and other processes.
[0047] The outer blind hole 13 is opened on the outer surface of the pole body. It can be circular and extends from the outside of the pole body to the inside. Its depth is greater than that of the outer pole body 11. That is, it penetrates the outer pole body 11 and extends into the inner pole body 12, so that there is no aluminum material residue at the bottom of the outer blind hole 13.
[0048] The inner blind hole 14 is opened on the inner surface of the pole body. It can be circular and extends from the inside to the outside of the pole body. Its depth is less than that of the inner layer 12 of the pole, that is, it does not penetrate the inner layer 12 of the pole.
[0049] The filler plug 15, which is an aluminum cylinder (e.g., a cylindrical body), is placed inside the outer blind hole 13 and welded to the pole body.
[0050] Here, the aluminum material mentioned includes pure aluminum and aluminum alloys, and the copper material mentioned includes pure copper and copper alloys. For example, the inner layer 12 of the electrode post can be made of T2-copper, and the outer layer 11 of the electrode post can be made of aluminum alloy, preferably 1-series or 3-series aluminum alloy.
[0051] In some alternative embodiments, the diameter of the outer electrode 11 may be larger than the diameter of the inner electrode 12.
[0052] In some alternative embodiments, the side of the pole body may have an annular groove 16, so that the longitudinal cross-section of the pole body may be I-shaped. That is, the middle position of the pole body has a neck with a smaller diameter, while the diameters of the upper and lower ends are larger than the middle neck. Optionally, the annular groove 16 may be partially formed in the outer layer 11 of the pole body and partially formed in the inner layer 12 of the pole body.
[0053] In some alternative embodiments, the thickness of the filler plug 15 may be equal to the depth of the outer blind hole 13, or 0.1 mm to 0.5 mm less than the depth of the outer blind hole 13.
[0054] In some alternative embodiments, the distance H between the bottom of the outer blind hole 13 and the bottom of the inner blind hole 14 is between 0.4 mm and 2 mm.
[0055] In some alternative embodiments, the surface of the outer blind hole 13 is roughened (e.g., frosted) or coated with a layer of black light-absorbing material (e.g., black adhesive). This increases light absorption and reduces the defect rate of subsequent welding processes.
[0056] In some alternative embodiments, the edges of the filler plug 15 are chamfered or rounded, and the chamfers or rounded corners on symmetrical sides are of equal size to facilitate mating with the outer blind hole 13.
[0057] In some alternative embodiments, the edges of the inner blind hole 14 and the outer blind hole 13 are respectively chamfered or rounded to facilitate mating with the filler plug 15, etc.
[0058] refer to Figure 2 , Figure 2 A cross-sectional structure of one embodiment of the negative electrode component of this application is shown. Figure 2 As shown, the negative electrode assembly of this application is suitable for cylindrical cells and includes:
[0059] The substrate 20 has a central through hole and is sleeved on the composite pole 10;
[0060] like Figure 1 The composite pole 10 shown is inserted through the central through hole of the substrate 20;
[0061] An insulating sealing gasket 30 is disposed between the composite pole 10 and the substrate 20;
[0062] The negative electrode current collector 40 is made of copper and has a boss that extends into the inner blind hole 14 of the composite electrode post 10 and is welded and interconnected with the inner layer 12 of the electrode post.
[0063] Here, the base 20 can be disc-shaped; it can be a cover or the bottom surface of a cup-shaped shell. A circular central through hole is formed in the center of the base 20, and a composite pole 10 is disposed at the central through hole.
[0064] Here, the longitudinal section of the composite pole 10 can be I-shaped, with its narrower neck embedded in the central through hole of the base 20, and the diameters at both ends can be larger than the central through hole.
[0065] Here, an insulating sealing gasket 30 is provided between the composite pole 10 and the substrate 20 to insulate and isolate the two and prevent them from contacting and short-circuiting.
[0066] Here, the negative current collector 40 is disc-shaped and made of copper, which can be pure copper or copper alloy. For example, it can be nickel-plated copper.
[0067] In some alternative embodiments, the boss can be formed by stamping, and the diameter of the boss is equal to or slightly smaller than the diameter of the inner blind hole 14.
[0068] In some alternative embodiments, the height of the boss is equal to the depth of the inner blind hole 14, or the height of the boss is 0.1 mm to 0.5 mm greater than the depth of the inner blind hole 14.
[0069] In some alternative embodiments, the negative current collector 40 has a recess on the other side corresponding to the boss, and a copper pad 50 is disposed in the recess. The copper pad 50 is riveted into the recess to increase the overall thickness of the protrusion of the negative current collector 40, thereby improving the subsequent welding yield.
[0070] In some alternative embodiments, the total thickness h from the bottom surface of the copper pad 50 to the top surface of the boss is between 0.4 mm and 2 mm, the distance H between the bottom of the outer blind hole of the pole body and the bottom of the inner blind hole of the pole body is between 0.4 mm and 2 mm, and the ratio of H to h is between 0.6 and 1.4.
[0071] refer to Figure 3 and Figure 4 The structure of the cylindrical battery cell of this application is shown. Figure 3 and Figure 4 As shown, the cylindrical battery cell of this application includes:
[0072] like Figure 2 The negative electrode assembly shown includes a composite electrode post 10, a substrate 20, an insulating sealing gasket 30, a negative electrode current collector 40, and a copper pad 50; and
[0073] The casing is 60, the core is 70, the positive current collector is 80, and the end cap is 90.
[0074] In some alternative embodiments, the base 20 and the housing 60 can be an integral structure, that is, the housing 60 can be a cup shape with an opening at one end and a bottom surface at the other end, and the base 20 can be the bottom surface of the housing 60.
[0075] In some alternative embodiments, the base 20 and the shell 60 can also be independent structures. For example, the base 20 is a disc-shaped cover, and the shell 60 is a cylinder with openings at both ends, which are joined together by welding or other means.
[0076] Next, refer to Figure 5 The assembly process of the negative electrode component of this application is shown:
[0077] Step S1. The current collector boss is inserted into the blind hole inside the composite electrode post and makes close contact with the bottom of the blind hole; wherein, the composite electrode post, the substrate, and the insulating sealing gasket have been assembled.
[0078] Step S2. The laser is injected from the outside into the bottom of the blind hole on the outside of the composite electrode post, penetrates the copper layer between the two blind holes of the electrode post body, and welds the current collector and the composite electrode post together; where the filled semi-circular area in the figure is the weld pool, and the black arrow above is the laser incident direction;
[0079] Step S3. Insert the filler plug into the blind hole on the outside of the composite electrode post, and use a laser to weld the filler plug and the composite electrode post together.
[0080] The present application proposes a composite electrode post, a negative electrode assembly, and a cylindrical battery cell. The key technical points and corresponding technical effects of this application include:
[0081] 1. Pole post design: The composite pole post structure design ensures that there is no aluminum material residue at the bottom of the outer blind hole, making it feasible to laser weld the composite pole post and current collector from the outside.
[0082] 2. Filler Plug: By designing a filler plug and inserting it into the outer blind hole, the finished product has no exposed copper material, avoiding electrochemical corrosion during cell use. In addition, the chamfer (or rounded corner) of the filler plug and the chamfer (or rounded corner) of the outer blind hole opening edge of the electrode post can provide space to accommodate the welding molten pool, preventing the excess height of the welding pool from affecting the height of the composite electrode post after welding.
[0083] 3. Process design: Through structural optimization, the parameter window of the welding process was improved, thereby improving the welding effect and yield.
[0084] Although this application has been described and illustrated with reference to specific embodiments thereof, such description and illustration are not limiting of this application. It will be readily understood by those skilled in the art that various changes can be made and equivalent components can be substituted within embodiments without departing from the true spirit and scope of this application as defined by the appended claims. Illustrations may not be drawn to scale. Differences may exist between the technical representation in this application and actual implementation due to variables in the manufacturing process, etc. Other embodiments of this application may exist that are not specifically described. The specification and illustrations should be considered illustrative rather than restrictive. Modifications can be made to adapt particular circumstances, materials, composition, methods, or processes to the objectives, spirit, and scope of this application. All such modifications fall within the scope of the appended claims. While the methods disclosed herein have been described with reference to specific operations performed in a particular order, it should be understood that these operations can be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of this application. Therefore, unless specifically indicated herein, the order and grouping of operations do not limit this application.
Claims
1. A composite electrode, characterized in that, include: The electrode body includes an outer electrode layer made of aluminum and an inner electrode layer made of copper. The outer blind hole extends from the outer side of the pole body to the inner side, and its depth is greater than that of the outer layer of the pole. The inner blind hole extends from the inside to the outside of the pole body, and its depth is less than that of the inner layer of the pole. The filler plug, an aluminum column, is placed inside the outer blind hole and welded to the pole body.
2. The composite electrode according to claim 1, characterized in that, The thickness of the filling plug is equal to the depth of the outer blind hole, or 0.1mm-0.5mm less than the depth of the outer blind hole.
3. The composite electrode according to claim 1, characterized in that, The longitudinal section of the pole post is I-shaped, and the side of the pole post has an annular groove.
4. The composite electrode according to claim 1, characterized in that, The distance H between the bottom of the outer blind hole and the bottom of the inner blind hole is between 0.4 mm and 2 mm.
5. The composite electrode according to claim 1, characterized in that, The surface of the outer blind hole is roughened or covered with a layer of black light-absorbing material.
6. A negative electrode component, characterized in that, include: The substrate has a central through-hole; The composite pole as described in claim 1 is inserted through the central through hole; An insulating sealing gasket is disposed between the composite pole and the substrate; The negative electrode current collector is made of copper and has a boss that extends into the inner blind hole of the composite electrode post and is welded and interconnected with the inner electrode post component of the composite electrode post.
7. The negative electrode assembly according to claim 6, characterized in that, The height of the boss is equal to the depth of the inner blind hole, or is 0.1mm-0.5mm greater than the depth of the inner blind hole.
8. The negative electrode assembly according to claim 6, characterized in that, The negative electrode current collector has a recess on the other side corresponding to the boss, and a copper pad is provided in the recess.
9. The negative electrode assembly according to claim 8, characterized in that, The total thickness h from the bottom surface of the copper pad to the top surface of the boss is between 0.4mm and 2mm, the distance H between the bottom of the outer blind hole of the pole body and the bottom of the inner blind hole of the pole body is between 0.4mm and 2mm, and the ratio of H to h is between 0.6 and 1.
4.
10. A cylindrical battery cell, characterized in that, include: The negative electrode component as described in claim 6.