Negative electrode connection method of cylindrical battery

Abstract

The invention provides a cathode connection method of a cylindrical battery, which comprises the following steps: step S1, fastening and connecting a cathode confluence sheet with the inner wall surface of the shell bottom of a shell in advance to form a pre-assembled accessory; s2, placing the roll core in an accommodating cavity of the pre-assembled accessory, and enabling a negative electrode lug of the roll core to face one side of the negative electrode bus sheet; and S3, carrying out one-time welding connection on the shell bottom of the shell, the negative electrode confluence sheet and the negative electrode tab through a laser. The invention solves the problem of high cost of the cathode connection mode of the cylindrical battery in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field, and in particular to a method for connecting a negative electrode of a cylindrical battery. Background Art

[0002] As the mainstream product of new energy vehicle power batteries, the safety of high energy density cylindrical batteries has attracted widespread attention. When the battery cell is in working condition, when an external short circuit or internal overheating occurs, a large amount of heat is generated inside the battery, causing the electrolyte to decompose, reducing gas to be generated inside the battery, and the battery to rupture, resulting in overheating, combustion or explosion. Most accidents are caused by short circuits inside the battery, which are caused by electrolyte leakage, short circuits between positive and negative electrodes, or local high temperatures inside the battery cell.

[0003] Internal short circuit of the battery can cause a short circuit between the positive and negative electrodes or between the positive and negative electrodes and the outer casing, causing the internal temperature of the battery to rise rapidly and causing the battery to work abnormally. In severe cases, a large amount of heat is generated inside the battery, the electrolyte decomposes and produces a large amount of gas, the battery ruptures, and causes the battery to burn or explode.

[0004] In the prior art, the negative electrode busbar is usually first welded to the negative electrode foil of the core by laser penetration welding, and then the negative electrode busbar is welded to the bottom of the steel shell by laser penetration welding. The two consecutive laser weldings result in high processing and manufacturing costs of the battery. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for connecting the negative electrode of a cylindrical battery to solve the problem of high cost of the negative electrode connection method of a cylindrical battery in the prior art.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a negative electrode connection method for a cylindrical battery, comprising the following steps: step S1, pre-tightening the negative electrode busbar to the inner wall surface of the shell bottom of the shell to form a pre-assembled accessory; step S2, placing the winding core in the accommodating cavity of the pre-assembled accessory, and making the negative electrode tab of the winding core face the negative electrode busbar; step S3, using a laser to perform a one-time welding connection on the shell bottom, the negative electrode busbar, and the negative electrode tab of the shell.

[0007] In an exemplary embodiment, in step S1 , the negative electrode bus bar is connected to the inner wall surface of the bottom of the housing by resistance spot welding.

[0008] In an exemplary embodiment, in step S1 , a plurality of spot welding structures are formed between the negative electrode bus bar and the inner wall surface of the shell bottom of the shell, and the plurality of spot welding structures are all located on the same circle.

[0009] In an exemplary embodiment, a distance L1 between each spot welding structure and the geometric center of the negative electrode bus bar and a distance L2 between each spot welding structure and the outer periphery of the negative electrode bus bar satisfy: L1>L2.

[0010] In an exemplary embodiment, in step S3, the shell bottom of the shell, the negative electrode bus bar, and the negative electrode tab are welded and connected at one time by laser welding outside the shell bottom of the shell.

[0011] In an exemplary embodiment, in step S3, a laser welding track is pre-set on the outer surface of the shell bottom of the shell, so that the laser performs welding operations according to the laser welding track.

[0012] In an exemplary embodiment, the laser welding track includes a plurality of sub-welding tracks, the plurality of sub-welding tracks extend radially, and each sub-welding track avoids the geometric center of the shell bottom.

[0013] In an exemplary embodiment, each sub-welding trajectory extends in a spiral shape; or, each sub-welding trajectory extends along a straight line; or, each sub-welding trajectory extends along a curve.

[0014] In an exemplary embodiment, the laser welding trajectory includes multiple sub-welding trajectories, each of which is arc-shaped and arranged at circumferential intervals around the shell bottom. The multiple arc-shaped sub-welding trajectories are located on the same circle and avoid the geometric center of the shell bottom; or, the laser welding trajectory includes multiple sub-welding trajectories, each of which is grid-shaped, and each sub-welding trajectory avoids the geometric center of the shell bottom.

[0015] In an exemplary embodiment, in step S2, after the winding core is placed in the accommodating cavity, a pressing force is applied to the winding core to make the negative electrode tab fit with the negative electrode bus bar.

[0016] By applying the technical solution of the present invention, a negative electrode connection method for a cylindrical battery is provided, which includes the following steps: step S1, pre-fastening the negative busbar to the inner wall surface of the shell bottom of the shell to form a pre-assembled accessory; step S2, placing the winding core in the accommodating cavity of the pre-assembled accessory, and making the negative electrode tab of the winding core face the negative electrode busbar; step S3, using a laser to perform a one-time welding connection on the shell bottom, the negative busbar, and the negative electrode tab of the shell. In this way, by pre-fastening the negative busbar to the inner wall surface of the shell bottom of the shell to form a pre-assembled accessory, after the winding core is placed in the accommodating cavity of the pre-assembled accessory, the shell bottom, the negative busbar, and the negative electrode tab of the shell are welded and connected once by a laser. That is to say, in this application, only one laser welding is required, and there is no need to perform laser welding multiple times, which is conducive to reducing the processing and manufacturing cost of cylindrical batteries and ensuring the economic efficiency of processing and manufacturing of cylindrical batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 A schematic flow chart of a method for connecting a negative electrode of a cylindrical battery according to an optional embodiment of the present invention is shown;

[0019] Figure 2 A schematic cross-sectional view of a cylindrical battery according to an optional embodiment of the present invention is shown;

[0020] Figure 3 A schematic cross-sectional structure diagram of resistance spot welding between the negative electrode bus bar and the inner wall surface of the shell bottom of the shell in step S1 is shown;

[0021] Figure 4 A schematic diagram showing the spot welding structure position of the resistance spot welding between the negative electrode bus bar and the inner wall surface of the shell bottom of the shell in step S1 is shown;

[0022] Figure 5 The cross-sectional structure schematic diagram of the laser welding the shell bottom, the negative electrode bus bar and the negative electrode tab of the shell at one time in step S3 is shown;

[0023] Figure 6 A schematic structural diagram of the laser welding track in step S3 is shown.

[0024] The above drawings include the following reference numerals:

[0025] 10. Negative busbar; 11. Spot welding structure;

[0026] 20. Shell; 21. Accommodating cavity; 22. Laser welding track; 221. Sub-welding track;

[0027] 30. Roll core. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In order to solve the problem of high cost of the negative electrode connection method of cylindrical batteries in the prior art, the present invention provides a negative electrode connection method of a cylindrical battery.

[0030] like Figures 1 to 6 As shown, the negative electrode connection method of the cylindrical battery includes the following steps:

[0031] Step S1, pre-fastening and connecting the negative electrode busbar 10 to the inner wall surface of the bottom of the shell 20 to form a pre-assembled component;

[0032] Step S2, placing the winding core 30 in the receiving cavity 21 of the pre-assembled component, and making the negative electrode tab of the winding core 30 face the negative electrode busbar 10;

[0033] Step S3, using a laser to weld the shell bottom of the shell 20, the negative electrode bus bar 10, and the negative electrode tab together at one time.

[0034] A pre-assembled accessory is formed by pre-fastening the negative electrode busbar 10 to the inner wall surface of the shell bottom of the shell 20, and then placing the winding core 30 in the accommodating cavity 21 of the pre-assembled accessory. The shell bottom of the shell 20, the negative electrode busbar 10, and the negative electrode tab are welded and connected at one time by a laser. That is to say, only one laser welding is required in the present application, and there is no need to perform laser welding multiple times, which is beneficial to reducing the processing and manufacturing cost of the cylindrical battery and ensuring the economic efficiency of the processing and manufacturing of the cylindrical battery. In addition, since the shell bottom of the shell 20, the negative electrode busbar 10, and the negative electrode tab are connected by a one-time laser welding, the current transmission path is shorter, so that the negative electrode current of the cylindrical battery can be directly transmitted to the shell 20, which is beneficial to reducing the internal resistance.

[0035] It should be noted that in the present application, in step S1, the negative electrode busbar 10 is connected to the inner wall surface of the bottom of the shell 20 by resistance spot welding. In this way, the reliability of the welding connection between the negative electrode busbar 10 and the inner wall surface of the bottom of the shell 20 is ensured.

[0036] like Figure 3 and Figure 4 As shown, in step S1, a plurality of spot welding structures 11 are formed between the negative busbar 10 and the inner wall surface of the shell bottom of the shell 20, and the plurality of spot welding structures 11 are all located on the same circle. In this way, the plurality of spot welding structures 11 are all located on the same circle, which can ensure that the connection between the negative busbar 10 and the shell bottom of the shell 20 is more firmly connected, thereby improving the durability of the cylindrical battery in a vibration environment.

[0037] like Figure 3 As shown, the distance L1 between each spot welding structure 11 and the geometric center of the negative electrode busbar 10 and the distance L2 between each spot welding structure 11 and the outer periphery of the negative electrode busbar 10 satisfy: L1>L2. In this way, it is ensured that each spot welding structure 11 can avoid the geometric center of the negative electrode busbar 10.

[0038] like Figure 5 As shown, in step S3, the shell bottom of the shell 20, the negative busbar 10, and the negative electrode tab are welded and connected at one time by laser welding outside the shell bottom of the shell 20. In this way, since the negative busbar 10 is tightly connected to the inner wall surface of the shell bottom of the shell 20 and forms a pre-assembled part, after the winding core 30 is placed in the accommodating cavity 21 of the pre-assembled part, the laser welding operation is performed outside the shell bottom of the shell 20. While ensuring the reliability of the welding connection between the shell bottom of the shell 20, the negative busbar 10, and the negative electrode tab, since the winding core 30 is covered in the accommodating cavity 21, the laser penetration welding operation is only performed on the outer surface of the shell bottom of the shell 20, which greatly reduces the risk of smoke generated during laser welding entering the inside of the winding core 30.

[0039] like Figure 6 As shown, in step S3, a laser welding track 22 is pre-set on the outer surface of the shell bottom of the shell 20, so that the laser performs welding according to the laser welding track 22. In this way, the welding reliability of the laser according to the pre-set laser welding track 22 is ensured.

[0040] It should be noted that, in the present application, the position of the laser welding track 22 can be distributed at almost any position around the outer surface of the shell bottom of the shell 20, and can be adaptively adjusted according to welding requirements, with good compatibility.

[0041] It should be noted that, in the present application, the laser welding track 22 includes a plurality of sub-welding tracks 221, and the plurality of sub-welding tracks 221 extend radially, and each sub-welding track 221 avoids the geometric center of the shell bottom. In this way, it is ensured that the cylindrical battery manufactured by the negative electrode connection method provided by the present application has as little risk of leakage as possible.

[0042] Optionally, each sub-welding track 221 extends in a spiral shape. In this way, the spirally designed laser penetration welding track can more evenly cover the bottom of the cylindrical battery while avoiding the geometric center of the bottom of the shell 20, thereby improving the uniformity of welding and the reliability of connection. The application scenarios of cylindrical batteries include batteries that require high stability, such as power supply batteries for medical equipment and precision instruments.

[0043] Optionally, each sub-welding track 221 extends along a straight line, so as to ensure the welding reliability of the laser penetration welding.

[0044] Optionally, each sub-welding track 221 extends along a curve, so as to ensure the welding reliability of the laser penetration welding.

[0045] It should be noted that in an embodiment not shown in the figure of the present application, the laser welding track 22 includes a plurality of sub-welding tracks 221, and the plurality of sub-welding tracks 221 are arc-shaped and are arranged at circumferential intervals around the shell bottom. The plurality of arc-shaped sub-welding tracks 221 are located on the same circle and avoid the geometric center of the shell bottom.

[0046] It should be noted that in an embodiment of the present application that is not shown in the figure, the laser welding track 22 includes a plurality of sub-welding tracks 221, and the plurality of sub-welding tracks 221 are all in a grid shape, and each sub-welding track 221 avoids the geometric center of the shell bottom. In this way, the grid-shaped laser penetration welding track can form denser welding points, improve the efficiency of current transmission and the overall performance of the battery, and the application scenarios of cylindrical batteries include high-performance batteries, such as battery packs for supercomputers and data centers.

[0047] like Figure 1 As shown, in step S2, after the winding core 30 is placed in the accommodating chamber 21, a pressing force is applied to the winding core 30 to make the negative electrode tab fit with the negative electrode busbar 10. In this way, the tight fit reliability between the negative electrode tab and the negative electrode busbar 10 is ensured.

[0048] Optionally, the welding power of laser penetration welding is adjustable between 1000 W and 2000 W. The adjustable welding power makes the welding process more flexible and can be adjusted according to different materials and thicknesses, thereby improving the adaptability and efficiency of welding. The welding power is suitable for the manufacture of batteries of various specifications and types.

[0049] Optionally, the welding speed of laser penetration welding is adjustable between 10 mm / s and 30 mm / s. The adjustable welding speed can optimize the welding process, ensure welding quality and improve production efficiency, and the welding speed is suitable for fast production lines of battery manufacturing, such as the production of batteries for consumer electronics.

[0050] Optionally, inert gas protection is used during laser penetration welding. Inert gas protection can avoid oxidation during welding, improve the conductivity of the welding point and the service life of the battery; it is suitable for batteries that require high conductivity and long life, such as electric vehicle batteries and industrial energy storage batteries.

[0051] Optionally, the negative busbar 10 is made of copper or copper alloy. The use of copper or copper alloy improves the conductivity of the negative busbar 10, reduces energy loss during current transmission, and is suitable for batteries with high power output, such as batteries for electric tools and electric bicycles.

[0052] Optionally, the negative electrode tab of the winding core 30 is a negative electrode foil, and the thickness of the negative electrode foil is between 10 μm and 20 μm. By reasonably optimizing the thickness of the negative electrode foil, the performance and cost of the cylindrical battery can be balanced, the cost performance of the cylindrical battery is improved, and it is suitable for the cost-sensitive battery market, such as batteries for home electronic products and mobile devices.

[0053] Optionally, the density of welding points between the negative electrode busbar 10 and the negative electrode foil is not less than 10 per square centimeter. High-density welding points improve the efficiency of current transmission, reduce the resistance inside the battery, and improve the performance of the battery, and are suitable for batteries that require high energy density, such as batteries for portable electronic devices and wearable devices.

[0054] Optionally, the distribution density of laser penetration welding around the bottom of the shell is not less than 2 welding points per centimeter. The high distribution density of welding points ensures the connection stability and reliability of the bottom of the battery, improves the overall performance of the battery, and is suitable for batteries that require high stability, such as batteries used for grid energy storage and solar energy storage.

[0055] Optionally, before laser penetration welding, the negative electrode busbar 10 and the negative electrode foil are pretreated, including surface cleaning and microstructure optimization. The pretreatment step can improve the success rate of welding and the overall performance of the battery. Surface cleaning can remove the oxide layer and impurities on the surface of the material. Microstructure optimization can improve the welding performance of the material, which is suitable for the preliminary preparation of battery manufacturing, such as material preparation and processing.

[0056] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0057] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0058] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0059] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0060] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for connecting the negative electrode of a cylindrical battery, characterized in that: The following steps are involved: Step S1, pre-fastening and connecting the negative electrode busbar (10) to the inner wall surface of the bottom of the shell (20) to form a pre-assembled component; Step S2, placing the winding core (30) in the accommodating cavity (21) of the pre-assembled component, and making the negative electrode tab of the winding core (30) face the negative electrode busbar (10); Step S3, using a laser to perform one-time welding connection on the shell bottom of the shell (20), the negative electrode busbar (10), and the negative electrode tab.

2. The negative electrode connection method according to claim 1, characterized in that: In the step S1, the negative electrode busbar (10) is connected to the inner wall surface of the shell bottom of the shell (20) by resistance spot welding.

3. The negative electrode connection method according to claim 2, characterized in that: In the step S1, a plurality of spot welding structures (11) are formed between the negative electrode busbar (10) and the inner wall surface of the shell bottom of the shell (20), and the plurality of spot welding structures (11) are all located on the same circle.

4. The negative electrode connection method according to claim 3, characterized in that: The distance L1 between each of the spot welding structures (11) and the geometric center of the negative electrode busbar (10), and the distance L2 between each of the spot welding structures (11) and the outer periphery of the negative electrode busbar (10) satisfy: L1>L2.

5. The negative electrode connection method according to claim 1, characterized in that: In the step S3, outside the shell bottom of the shell (20), the shell bottom of the shell (20), the negative electrode busbar (10), and the negative electrode tab are welded and connected at one time by laser welding.

6. The negative electrode connection method according to claim 5, characterized in that: In the step S3, a laser welding track (22) is pre-arranged on the outer surface of the shell bottom of the shell (20), so that the laser performs welding operations according to the laser welding track (22).

7. The negative electrode connection method according to claim 6, characterized in that: The laser welding track (22) comprises a plurality of sub-welding tracks (221), the plurality of sub-welding tracks (221) extend radially, and each of the sub-welding tracks (221) avoids the geometric center of the shell bottom.

8. The negative electrode connection method according to claim 7, characterized in that: Each of the sub-welding tracks (221) extends in a spiral shape; or, Each of the sub-welding tracks (221) extends along a straight line; or, Each of the sub-welding tracks (221) extends along a curve.

9. The negative electrode connection method according to claim 6, characterized in that: The laser welding track (22) comprises a plurality of sub-welding tracks (221), the plurality of sub-welding tracks (221) are all arc-shaped and are arranged at intervals around the circumference of the shell bottom, the plurality of arc-shaped sub-welding tracks (221) are located on the same circle and avoid the geometric center of the shell bottom; or, The laser welding track (22) comprises a plurality of sub-welding tracks (221), the plurality of sub-welding tracks (221) are all in a grid shape, and each of the sub-welding tracks (221) avoids the geometric center of the shell bottom.

10. The negative electrode connection method according to any one of claims 1 to 9, characterized in that: In the step S2, after the winding core (30) is placed in the accommodating cavity (21), a pressing force is applied to the winding core (30) so that the negative electrode tab is attached to the negative electrode busbar (10).

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