Battery assembly and secondary battery

Abstract

The application provides a battery assembly and a secondary battery. The material of a negative pole post is usually copper or nickel. When the negative pole post and a negative pole connecting piece are welded, a high welding power parameter is required. In the embodiment, an opening is arranged in the middle of the negative pole post welding part of the negative pole connecting piece, a boss corresponding to the opening is arranged in the middle of the negative pole post, the edge of the boss is welded with the edge of the opening through laser splice welding, the overcurrent area is increased, the large current requirement during rapid charging is met, laser penetration welding with a small welding area is performed around the opening, welding heat is reduced, and the insulation failure caused by the large welding area is avoided.

Description

Technical Field

[0001] This application relates to the field of power battery technology, and more specifically, to a battery assembly and a secondary battery. Background Technology

[0002] In current battery manufacturing processes, the welding of the positive and negative electrode tabs to the terminal posts of the top cover typically employs a precise and efficient laser penetration welding technique. The weld marks often appear as several parallel and precise line segments, which not only ensure the stability of the weld but also contribute to its aesthetics. However, depending on the actual application requirements of the battery, to meet the higher current carrying capacity requirements in certain scenarios, some designs intentionally increase the welding area to enhance current carrying capacity. A more direct approach is to omit the connecting tabs and directly weld the JR tabs to the terminal posts, thereby simplifying the structure and improving current transmission efficiency.

[0003] However, whether using a multi-segment welding mark design or directly welding the JR tab to the terminal post, these methods have limitations in terms of the current-carrying area between the connecting piece and the terminal post. Especially in high-rate fast charging scenarios, this limited current-carrying area is insufficient to meet the high current demands of fast charging. While increasing the welding area can be a solution to improve current-carrying capacity, it also introduces new problems. Particularly on the negative side, an excessively large welding area can easily lead to high temperatures generated during the welding process. These high temperatures can easily melt adjacent plastic materials, potentially causing a serious risk of insulation failure. Summary of the Invention

[0004] The purpose of this application is to provide a battery assembly and a secondary battery, which addresses the problem that existing battery design and manufacturing methods have limited current-carrying area, making it difficult to meet the high current requirements during fast charging, and that excessively large welding area can easily lead to insulation failure caused by high temperatures generated during welding.

[0005] This application provides a battery assembly, including: a negative electrode connecting piece and a top cover;

[0006] The negative electrode connector includes a negative electrode post welding part and a negative electrode lug welding part, with an opening in the middle of the negative electrode post welding part; the negative electrode lug welding part is welded to the negative electrode lug.

[0007] The top cover includes a top cover substrate and a negative electrode post; the negative electrode post is disposed on one side of the top cover substrate; a boss is provided in the middle of the negative electrode post, and the boss is adapted to the opening;

[0008] The edge of the boss is welded to the edge of the opening by laser splicing welding, and a part of the area around the opening of the negative electrode post is welded to the negative electrode post by laser penetration welding.

[0009] In the above technical solutions, the material of the negative electrode post is usually copper or nickel. The welding power parameters required when welding the negative electrode post and the negative electrode connecting piece are relatively high. In this embodiment, an opening is set in the middle of the negative electrode post welding part of the negative electrode connecting piece, and a boss adapted to the opening is set in the middle of the negative electrode post. The edge of the boss is welded to the edge of the opening by laser splicing welding, which increases the current flow area and thus meets the high current demand during fast charging. In addition, laser penetration welding with a small welding area is performed around the opening to reduce welding heat and avoid insulation failure caused by excessive welding area.

[0010] In some alternative implementations, the boss is a raised frustum and the opening is a circular opening.

[0011] In the above technical solution, a raised frustum is provided in the middle of the negative electrode post, and a corresponding circular opening is provided for the negative electrode connecting piece. This design allows for precise alignment between the negative electrode post and the negative electrode connecting piece. This design reduces assembly difficulty and improves assembly accuracy. During assembly, the raised frustum can be easily inserted into the circular opening, ensuring a stable connection between the negative electrode post and the negative electrode connecting piece. The cooperation between the raised frustum and the circular opening increases the contact area between the negative electrode post and the negative electrode connecting piece, thereby improving the stability of the connection. This design allows the connecting piece to fit more tightly against the protrusion on the post, reducing loosening caused by vibration or other external factors. The increased contact area helps reduce contact resistance, thereby reducing energy loss and heat generation during current flow. Furthermore, the design of the raised frustum and the circular opening simplifies the manufacturing of the negative electrode post and the negative electrode connecting piece. This design can be achieved through simple processes such as stamping and cutting, reducing production costs.

[0012] In some alternative embodiments, a portion of the area surrounding the opening of the negative electrode welding portion is a circular welding area surrounding the opening.

[0013] In the above technical solution, welding a circular welding area around the circular opening effectively forms a fixed connecting ring between the negative electrode connector and the negative electrode post. This connecting ring restricts the rotation of the negative electrode connector relative to the negative electrode post, thus achieving an anti-torsion effect. This design ensures that the negative electrode connector and the negative electrode post maintain a stable connection during assembly and use, even under external forces, preventing torsion or misalignment. The welding of the circular welding area increases the connection area between the negative electrode connector and the negative electrode post, thereby improving the tensile strength of the connection.

[0014] In some optional embodiments, a positive electrode connector is also included; the positive electrode connector includes a positive electrode post welding portion and a positive electrode lug welding portion; the top cover also includes a positive electrode post;

[0015] The positive electrode tab welding part is welded to the positive electrode tab; the positive electrode post welding part is welded to the positive electrode post by laser penetration welding.

[0016] In the above technical solution, the positive electrode post is usually made of aluminum or stainless steel. The welding power parameters required when laser welding the positive electrode post and the positive electrode connecting piece are relatively low. Therefore, in this embodiment, the positive electrode post welding part and the positive electrode post are laser-penetrating welded over a large area, so that the current-carrying area can meet the high current requirements during fast charging, and it is also beneficial for assembly, reducing the probability of poor fit between the positive electrode connecting piece and the top cover.

[0017] In some alternative implementations, the welding trajectory between the positive electrode welding portion and the positive electrode includes multiple concentric circles of different radii, or a spiral.

[0018] In the above technical solution, the use of multiple concentric circles or spiral trajectories with different radii ensures a more uniform and dense heat distribution of the laser beam in the welding area. This helps reduce thermal stress concentration during welding and decreases the generation of welding defects (such as cracks and porosity). Multiple concentric circles or spiral welding trajectories also create a tighter and stronger connection between the positive electrode post and the welded part. This connection method significantly improves the tensile and shear strength of the weld, ensuring the safety and reliability of the battery during use. The spiral trajectory design allows the laser beam to scan the welding area continuously and smoothly, thereby reducing interruptions and repositioning time during the welding process. This helps improve welding efficiency and reduce production costs.

[0019] In some alternative embodiments, both the negative electrode tab welding portion and the positive electrode tab welding portion are structures with a central slot and symmetrical top and bottom. The upper and lower parts of the negative electrode tab welding portion are welded to the negative electrode tab, and the upper and lower parts of the positive electrode tab welding portion are welded to the positive electrode tab.

[0020] In the above technical solution, both the negative electrode connecting piece and the positive electrode connecting piece include a symmetrical structure to achieve butterfly welding with the electrode tabs. Butterfly welding, also known as lithium battery butterfly welding process, offers higher reliability and lower risk of desoldering and short circuits compared to traditional wire connection methods.

[0021] In some alternative embodiments, the negative electrode tab welding portion is ultrasonically welded to the negative electrode tab and / or laser welded to the positive electrode tab; the positive electrode tab welding portion is ultrasonically welded to the positive electrode tab and / or laser welded to the positive electrode tab.

[0022] In some alternative embodiments, the welding area between the negative electrode tab welding portion and the negative electrode tab is a plurality of parallel strip-shaped areas, and the welding area between the positive electrode tab welding portion and the positive electrode tab is a plurality of parallel strip-shaped areas.

[0023] In some alternative implementations, both the negative electrode connector and the positive electrode connector are asymmetrical structures;

[0024] The top cover also includes a lower plastic sheet, on which a limit post is provided to prevent the negative electrode connection piece and the positive electrode connection piece from being installed backwards during assembly.

[0025] In the above technical solution, the asymmetrical electrode connector design effectively avoids misoperation during assembly, especially on automated assembly lines. This design significantly reduces the risk of reverse installation, thereby improving battery safety. The setting of the limiting post further enhances this safety, physically preventing the negative and positive electrode connectors from being inserted in reverse during assembly, avoiding safety hazards such as short circuits caused by reverse installation. Furthermore, the limiting post ensures that the electrode connectors are fixed in position within the top cover, preventing performance degradation or damage that may result from positional changes. The asymmetrical connector structure makes it easier to identify and position on automated assembly lines, reducing assembly difficulty and improving production efficiency. The limiting post design also simplifies the assembly process, reducing the time spent on manual inspection and adjustment, further improving production efficiency.

[0026] This application provides a secondary battery, including a battery assembly as described above. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of the battery assembly provided in an embodiment of this application;

[0029] Figure 2 This is a schematic diagram of the negative electrode connection piece structure provided in an embodiment of this application;

[0030] Figure 3 This is a schematic diagram of the negative electrode post provided in an embodiment of this application;

[0031] Figure 4 A schematic diagram of the welding area of ​​the battery assembly provided in an embodiment of this application;

[0032] Figure 5 This is a schematic diagram of a secondary battery structure provided in an embodiment of this application.

[0033] Icons: 1-Negative electrode connector, 11-Negative electrode post welding part, 12-Negative electrode tab welding part, 111-Opening, 1111-Negative electrode tab welding area, 1112-Circular welding area, 1113-Laser splicing welding area, 112-Connecting part, 2-Top cover, 21-Top cover substrate, 22-Lower plastic, 221-Limiting post, 23-Negative electrode post, 231-Boss, 3-Positive electrode connector, 3111-Positive electrode tab welding area, 3112-Positive electrode post welding area. Detailed Implementation

[0034] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0035] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a battery assembly provided in an embodiment of the present application, including: a negative electrode connecting piece 1 and a top cover 2.

[0036] Please refer to Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the negative electrode connector 1 provided in an embodiment of this application. Figure 3 This is a schematic diagram of the negative electrode post 23 provided in the embodiment of this application; the negative electrode connecting piece 1 includes a negative electrode post welding part 11 and a negative electrode ear welding part 12, and an opening 111 is provided in the middle of the negative electrode post welding part 11; the negative electrode ear welding part 12 is welded to the negative electrode ear; the top cover 2 includes a top cover substrate 21 and a negative electrode post 23; the negative electrode post 23 is disposed on one side of the top cover substrate 21; a boss 231 is provided in the middle of the negative electrode post 23, and the boss 231 is adapted to the opening 111; the edge of the boss 231 and the edge of the opening 111 are welded by laser splicing welding, and a part of the area around the opening 111 of the negative electrode post welding part 11 is welded to the negative electrode post 23 by laser penetration welding.

[0037] In this embodiment, the material of the negative electrode post 23 is usually copper or nickel. The welding power parameters required when welding the negative electrode post 23 and the negative electrode connecting piece 1 are relatively high. In this embodiment, an opening 111 is provided in the middle of the negative electrode post welding part 11 of the negative electrode connecting piece 1, and a boss 231 adapted to the opening 111 is provided in the middle of the negative electrode post 23. The edge of the boss 231 and the edge of the opening 111 are welded together by laser splicing welding, which increases the current flow area and thus meets the high current demand during fast charging. In addition, laser penetration welding with a small welding area is performed around the opening 111 to reduce welding heat and avoid insulation failure caused by excessive welding area.

[0038] In some alternative embodiments, the boss 231 is a raised frustum, and the opening 111 is a circular opening.

[0039] In this embodiment, a raised frustum is provided in the middle of the negative electrode post 23, and a corresponding circular opening is provided in the negative electrode connecting piece 1. The design of the raised frustum and the circular opening enables precise alignment between the negative electrode post 23 and the negative electrode connecting piece 1. This design reduces assembly difficulty and improves assembly accuracy. During assembly, the raised frustum can be easily inserted into the circular opening, ensuring a stable connection between the negative electrode post 23 and the negative electrode connecting piece 1. The cooperation between the raised frustum and the circular opening increases the contact area between the negative electrode post 23 and the negative electrode connecting piece 1, thereby improving the stability of the connection. This design allows the connecting piece to fit more tightly against the protrusion 231 of the post, reducing loosening of the connection due to vibration or other external factors. The increased contact area helps to reduce contact resistance, thereby reducing energy loss and heat generation when current flows. Furthermore, the design of the raised frustum and the circular opening simplifies the manufacturing of the negative electrode post 23 and the negative electrode connecting piece 1. This design can be achieved through simple processes such as stamping and cutting, reducing production costs.

[0040] In some alternative embodiments, a portion of the area surrounding the opening 111 of the negative electrode welding portion 11 is a circular welding area 1112 surrounding the opening 111.

[0041] In this embodiment, a circular welding area 1112 is welded around the circular opening, which is equivalent to forming a fixed connecting ring between the negative electrode connecting piece 1 and the negative electrode post 23. This connecting ring can restrict the rotation of the negative electrode connecting piece 1 relative to the negative electrode post 23, thereby achieving an anti-torsion effect. This design ensures that the negative electrode connecting piece 1 and the negative electrode post 23 maintain a stable connection state during assembly and use, even under external forces, avoiding torsion or misalignment. The welding of the circular welding area 1112 increases the connection area between the negative electrode connecting piece 1 and the negative electrode post 23, thereby improving the tensile strength of the connection.

[0042] In some optional embodiments, a positive electrode connecting piece 3 is also included; the positive electrode connecting piece 3 includes a positive electrode post welding portion and a positive electrode lug welding portion; the top cover 2 also includes a positive electrode post;

[0043] The positive electrode tab is welded to the positive electrode tab; the positive electrode post is welded to the positive electrode post by laser penetration welding.

[0044] In this embodiment, the positive electrode post is usually made of aluminum or stainless steel. The welding power parameters required when laser welding the positive electrode post and the positive electrode connecting piece 3 are relatively low. Therefore, in this embodiment, the positive electrode post welding part and the positive electrode post are laser-penetrating welded over a large area, so that the current-carrying area can meet the high current requirements during fast charging, and it is also beneficial for assembly, reducing the probability of poor fit between the positive electrode connecting piece 3 and the top cover 2.

[0045] In some alternative implementations, the welding trajectory between the positive electrode welding portion and the positive electrode includes multiple concentric circles of different radii, or a spiral.

[0046] In this embodiment, using multiple concentric circles or spiral trajectories of different radii ensures a more uniform and dense heat distribution of the laser beam in the welding area. This helps reduce thermal stress concentration during welding and decreases the occurrence of welding defects such as cracks and porosity. Multiple concentric circles or spiral welding trajectories allow for a tighter and stronger connection between the positive electrode post and the welded part. This connection method significantly improves the tensile and shear strength of the weld, ensuring the safety and reliability of the battery during use. The spiral trajectory design allows the laser beam to scan the welding area continuously and smoothly, thereby reducing interruptions and repositioning time during the welding process. This helps improve welding efficiency and reduce production costs.

[0047] In some alternative embodiments, both the negative electrode tab welding portion 12 and the positive electrode tab welding portion have a central slot and are symmetrically arranged. The upper and lower parts of the negative electrode tab welding portion 12 are welded to the negative electrode tab, and the upper and lower parts of the positive electrode tab welding portion are welded to the positive electrode tab.

[0048] In this embodiment, both the negative electrode connecting piece 1 and the positive electrode connecting piece 3 include a symmetrical structure to achieve butterfly welding with the electrode tabs. Butterfly welding, also known as lithium battery butterfly welding process, offers higher reliability and lower risk of desoldering and short circuits compared to traditional wire connection methods.

[0049] In some alternative embodiments, the negative electrode tab welding portion 12 is ultrasonically welded to the negative electrode tab and / or laser welded; the positive electrode tab welding portion is ultrasonically welded to the positive electrode tab and / or laser welded.

[0050] In some alternative embodiments, the welding area between the negative electrode tab welding portion 12 and the negative electrode tab is a plurality of parallel strip-shaped areas, namely the negative electrode tab welding area 1111; the welding area between the positive electrode tab welding portion and the positive electrode tab is a plurality of parallel strip-shaped areas, namely the positive electrode tab welding area 3111.

[0051] In some optional embodiments, both the negative electrode connecting piece 1 and the positive electrode connecting piece 3 have asymmetrical structures; the top cover 2 also includes a lower plastic piece 22, on which a limiting post 221 is provided. The limiting post 221 is used to prevent the negative electrode connecting piece 1 and the positive electrode connecting piece 3 from being installed backwards during assembly. In this embodiment, the asymmetrical position of the negative electrode connecting piece and the positive electrode connecting piece is at the connection portion 112 between the semicircle and the rectangle of the connecting piece. This connection portion 112 adopts an asymmetrical foolproof design and cooperates with the limiting post to play a positioning and foolproof role.

[0052] In this embodiment, the asymmetrical electrode connector design effectively avoids misoperation during assembly, especially on automated assembly lines. This design significantly reduces the risk of reverse installation, thereby improving battery safety. The setting of the limiting post 221 further enhances this safety by physically restricting the reverse insertion of the negative electrode connector 1 and the positive electrode connector 3 during assembly, avoiding safety hazards such as short circuits caused by reverse installation. Furthermore, the limiting post 221 ensures that the electrode connector is fixed in position within the top cover 2, preventing performance degradation or damage that may result from positional changes. The asymmetrical connector structure makes it easier to identify and position on automated assembly lines, reducing assembly difficulty and improving production efficiency. The design of the limiting post 221 also simplifies the assembly process, reducing the time spent on manual inspection and adjustment, further improving production efficiency.

[0053] In this embodiment, during cell assembly, for the negative electrode side, the positive electrode tab and the positive electrode connecting piece are first ultrasonically welded, and the negative electrode tab and the negative electrode connecting piece are then ultrasonically welded. Next, the positive electrode tab and the positive electrode connecting piece are laser welded, and the negative electrode tab and the negative electrode connecting piece are then laser welded, forming a negative electrode tab welding area 1111 and a positive electrode tab welding area 3111. Afterwards, the positive electrode connecting piece and the negative electrode connecting piece with the welded tabs are welded to the top cover. Specifically, the boss of the negative electrode post and the opening of the negative electrode connecting piece are first laser-welded together to form a laser-welded area 1113, and then the negative electrode post and the negative electrode connecting piece are laser-through welded together to form a circular welding area 1112.

[0054] For the positive electrode side, since laser splicing welding has high requirements for dimensional tolerances, and the cumulative processing tolerances of the connecting piece and the pole, as well as the assembly tolerances of the connecting piece and the tab, will greatly increase the probability of poor fit between the connecting piece with the tab and the top cover. Therefore, in this embodiment, the positive electrode connecting piece and the positive electrode pole are welded by laser penetration welding.

[0055] Finally, please refer to Figure 4 , Figure 4 This is a schematic diagram of the welding area of ​​the battery assembly provided in the embodiments of this application. The current-carrying area of ​​the negative electrode post and the negative electrode connecting piece is equivalent to the sum of the areas of the annular welding area 1112 and the laser splicing welding area 1113. The current-carrying area of ​​the positive electrode post and the positive electrode connecting piece is the area of ​​the positive electrode post welding area 3112.

[0056] Currently, square aluminum-cased batteries are developing towards high capacity and high-rate fast charging, which places higher demands on the overcurrent capacity of the cells themselves. To meet these overcurrent requirements, the connecting pieces and terminals need to be laser-welded with spiral lines. However, due to the significant heat generated during welding, especially on the negative electrode side, the lower plastic 22 melts and deforms, posing a risk of insulation failure. Therefore, please refer to... Figure 5 , Figure 5 The present application also provides a schematic diagram of a secondary battery structure, including a battery assembly as described above. The positive electrode post and the positive electrode connecting piece 3 are laser-through welded, and the negative electrode post 23 and the negative electrode connecting piece 1 are laser-joint welded and laser-through welded. This can reduce welding heat while meeting overcurrent requirements and avoid the risk of insulation failure.

[0057] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0058] Furthermore, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0059] Furthermore, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0060] In this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, without necessarily requiring or implying any such actual relationship or order between these entities or operations.

[0061] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A battery assembly, characterized in that, include: Negative electrode connector and top cover; The negative electrode connector includes a negative electrode post welding part and a negative electrode lug welding part, wherein the negative electrode post welding part has an opening in the middle; the negative electrode lug welding part is welded to the negative electrode lug. The top cover includes a top cover substrate and a negative electrode post; the negative electrode post is disposed on one side of the top cover substrate; a boss is provided in the middle of the negative electrode post, and the boss is adapted to the opening; The edge of the boss is welded to the edge of the opening by laser splicing welding, and a portion of the area around the opening of the negative electrode welding part is welded to the negative electrode by laser penetration welding. It also includes a positive electrode connector; the positive electrode connector includes a positive electrode post welding part and a positive electrode lug welding part; the top cover also includes a positive electrode post; The positive electrode tab welding part is welded to the positive electrode tab; the positive electrode post welding part is welded to the positive electrode post by laser penetration welding.

2. The battery assembly as claimed in claim 1, characterized in that, The boss is a raised frustum, and the opening is a circular opening.

3. The battery assembly as described in claim 2, characterized in that, The area surrounding the opening of the negative electrode welding part is a circular welding area that surrounds the opening.

4. The battery assembly as claimed in claim 1, characterized in that, The welding trajectory between the positive electrode welding part and the positive electrode includes multiple concentric circles or spirals with different radii.

5. The battery assembly as claimed in claim 1, characterized in that, Both the negative electrode tab welding part and the positive electrode tab welding part have a groove in the middle and are symmetrical from top to bottom. The upper and lower parts of the negative electrode tab welding part are welded to the negative electrode tab, and the upper and lower parts of the positive electrode tab welding part are welded to the positive electrode tab.

6. The battery assembly as claimed in claim 1, characterized in that, The negative electrode tab welding part is connected to the negative electrode tab by ultrasonic welding and / or laser welding; the positive electrode tab welding part is connected to the positive electrode tab by ultrasonic welding and / or laser welding.

7. The battery assembly as claimed in claim 6, characterized in that, The welding area between the negative electrode tab and the negative electrode tab consists of multiple parallel strip-shaped areas, and the welding area between the positive electrode tab and the positive electrode tab also consists of multiple parallel strip-shaped areas.

8. The battery assembly as claimed in claim 1, characterized in that, Both the negative electrode connecting piece and the positive electrode connecting piece are asymmetrical structures; The top cover also includes a lower plastic sheet, on which a limiting post is provided. The limiting post is used to prevent the negative electrode connecting piece and the positive electrode connecting piece from being installed backwards during assembly.

9. A secondary battery, characterized in that, Includes the battery assembly as described in any one of claims 1-8.

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