Welding method and lithium battery capable of preventing welding penetration

Abstract

This invention provides a welding method and a lithium battery that prevents solder burn-through, relating to the field of battery technology. The solder burn-through prevention welding method includes the following steps: inserting an anti-break-through pad or anti-break-through material into the groove of the current collector; welding the current collector to the winding core; inserting the winding core and current collector into the cavity of the housing and fixing the winding core with tooling; and welding the bottom of the housing to the bottom of the groove via the outer side of the housing bottom. The solder burn-through prevention welding method provided by this invention, by setting an anti-break-through pad or anti-break-through material in the groove of the current collector, can prevent the electrode tabs from burning through during laser penetration welding of the current collector and the bottom of the housing, thus preventing short circuits and scrapping of the lithium battery winding core, and improving the yield rate of lithium battery manufacturing processes.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a welding method for preventing solder burn-through and a lithium battery. Background Technology

[0002] In existing cylindrical steel-cased lithium-ion battery structures with multiple tabs, the negative electrode current collector is bonded to the casing bottom using either traditional resistance spot welding or laser penetration welding. With resistance spot welding, the negative electrode current collector is fixed to the casing bottom by only one weld point, resulting in a small welding area, low current carrying capacity, and a tendency for incomplete welds. Incomplete welds lead to increased internal resistance and excessive temperature rise, affecting battery safety. On one hand, laser penetration welding offers a large welding area and a strong, reliable weld, resulting in stable and lower internal resistance compared to traditional resistance spot welding. On the other hand, laser penetration welding eliminates the need for spot welding pins, reducing the size of the core's center hole and increasing the material area, thus increasing the battery capacity for the same model. Therefore, laser penetration welding has replaced resistance spot welding. However, laser penetration welding often results in the tabs being welded through, causing short circuits and rendering the lithium-ion battery core unusable. Summary of the Invention

[0003] This invention provides a welding method to prevent burn-through, thereby solving the technical problem in the prior art where the electrode tabs are burned through during laser penetration welding, leading to short circuits and scrapping of lithium battery cores.

[0004] The present invention also provides a lithium battery.

[0005] A welding method for preventing burn-through according to a first aspect of the present invention includes the following steps:

[0006] Insert a puncture-resistant pad or puncture-resistant material into the groove of the manifold;

[0007] The collector plate is welded to the winding core;

[0008] The core and the collector plate are installed into the cavity of the housing, and the core is fixed by tooling.

[0009] The bottom of the housing is welded to the bottom of the groove via the outer side of the bottom of the housing.

[0010] According to an embodiment of the present invention, a welding method for preventing burn-through is provided. When the groove is filled with a material that prevents burn-through, the following steps are performed before performing the step of welding the manifold to the core:

[0011] The puncture-resistant material inside the groove is dried.

[0012] According to an embodiment of the present invention, a welding method for preventing weld burn-through is provided, wherein the manifold is welded to the core via an elastic connector.

[0013] According to an embodiment of the present invention, a welding method for preventing weld burn-through is provided, wherein the welding position between the bottom of the shell and the bottom of the tank is located at the center of the bottom of the tank.

[0014] According to an embodiment of the present invention, a welding method for preventing weld penetration is provided, wherein the bottom of the housing and the bottom of the tank are connected by laser welding, and the laser beam forms an acute angle with the bottom of the housing.

[0015] The present invention also provides a lithium battery based on the welding method for preventing solder burn-through described in any one of the above claims, the lithium battery comprising:

[0016] The shell has an internal cavity.

[0017] The core is disposed within the cavity;

[0018] A collector plate is disposed in the cavity and located between the core and the bottom of the housing. The collector plate is welded to the core. The edge of the collector plate forms a groove with the opening facing the core. A puncture-resistant pad or puncture-resistant material is inserted into the groove. The bottom of the groove abuts against the bottom of the housing and is welded to the bottom of the housing.

[0019] According to the lithium battery provided in the embodiment of the present invention, the groove is an annular groove, and the groove wall away from the center of the collector is provided with an arc angle, the radius of the arc angle being R, 0.35mm≤R≤0.65mm.

[0020] According to an embodiment of the present invention, the current collector is provided with a plurality of elastic connectors, the elastic connectors being welded to the winding core; a gap is formed between the elastic connectors and the current collector, and at least one side of the elastic connector is connected to the current collector; the plurality of elastic connectors are equidistantly arranged around the outer periphery of the center of the current collector.

[0021] According to an embodiment of the present invention, a protrusion is formed at the center of the current collector on the side opposite to the winding core. The protrusion abuts against the bottom of the housing. The outer diameter of the protrusion is φ4.3mm, the height of the protrusion is 0.4mm-0.6mm, and the taper of the protrusion is 1:1.

[0022] According to the lithium battery provided in the embodiment of the present invention, the depth of the groove is 0.2mm-0.4mm and the width of the groove is 0.2mm-0.5mm; the anti-breakdown pad is a ceramic pad and the anti-breakdown material is AT9 material.

[0023] The welding method for preventing burn-through provided in this invention can prevent the electrode tabs from burning through during laser penetration welding of the current collector and the bottom of the casing, thus preventing short circuits and scrapping of the lithium battery core, and improving the yield rate of lithium battery manufacturing process by setting an anti-break-through pad or anti-break-through material in the groove of the current collector. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this invention 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the front cross-sectional structure of a lithium battery provided in an embodiment of the present invention;

[0026] Figure 2 This is provided by the embodiments of the present invention. Figure 1 A magnified schematic diagram of the local structure at point A;

[0027] Figure 3 This is provided by the embodiments of the present invention. Figure 1 A magnified schematic diagram of the local structure at point B;

[0028] Figure 4 This is a top view of the collector structure provided in an embodiment of the present invention;

[0029] Figure 5 This is provided by the embodiments of the present invention. Figure 4 A schematic diagram of the cross-sectional structure along section line AA;

[0030] Figure 6 This is provided by the embodiments of the present invention. Figure 5 A magnified schematic diagram of the local structure at point C;

[0031] Figure 7 This is provided by the embodiments of the present invention. Figure 5 A magnified schematic diagram of the local structure at point D;

[0032] Figure 8 This is one of the flowcharts of a welding method for preventing weld burn-through provided in an embodiment of the present invention;

[0033] Figure 9 This is a schematic diagram of the welding trajectory of a welding method for preventing weld burn-through provided in an embodiment of the present invention;

[0034] Figure 10 This is the second flowchart of a welding method for preventing weld burn-through provided in an embodiment of the present invention.

[0035] Figure label:

[0036] 100. Housing; 110. Bottom of housing; 200. Core; 300. Collector plate; 310. Groove; 320. Puncture pad or puncture resistant material; 330. Flexible connector; 340. Rounded corner; 350. Gap; 360. Protrusion; 400. Welding trajectory. Detailed Implementation

[0037] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0038] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0040] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0042] The following is combined Figures 1-10 This invention describes a welding method for preventing solder burn-through and a lithium battery according to embodiments of the present invention.

[0043] Figure 8 One example of a welding method for preventing weld burn-through provided by an embodiment of the present invention is illustrated in the flowchart, such as... Figure 8 As shown, the welding method for preventing weld burn-through includes the following steps:

[0044] Step 100: Insert a puncture-resistant pad or puncture-resistant material 320 into the groove 310 of the manifold 300.

[0045] The puncture-resistant pad can be a ceramic liner, and the puncture-resistant material can be AT9 material. The puncture-resistant pad or puncture-resistant material 320 can either fill the interior space of the groove 310 completely or only fill part of the space of the groove 310.

[0046] Step 200: Weld the collector plate 300 to the core 200.

[0047] The collector plate 300 and the core 200 can be welded together by laser welding. In one embodiment of the invention, the elastic connector 330 is welded to the core 200.

[0048] Step 300: Insert the core 200 and the collector plate 300 into the cavity of the housing 100, and fix the core 200 with tooling.

[0049] Fixing the core 200 with tooling can prevent misalignment between the core 200 and the collector plate 300 during the welding process.

[0050] Step 400: The bottom of the housing 110 is welded to the bottom of the groove 310 via the outer side of the bottom of the housing 110.

[0051] Laser penetration welding is used to weld from the outside of the bottom 110 of the housing to the inside, so that the bottom 110 of the housing and the bottom of the groove 310 melt and then solidify together. During welding, the laser beam forms an acute angle with the bottom of the housing, although the laser beam can also be perpendicular to the bottom of the housing.

[0052] The welding method for preventing weld penetration provided in this embodiment of the invention, by setting an anti-penetration pad or anti-penetration material 320 in the groove 310 of the current collector 300, can prevent the electrode tabs from being welded through during laser penetration welding of the current collector 300 and the bottom 110 of the housing, thus preventing the lithium battery core 200 from short-circuiting and being scrapped, and improving the yield rate of lithium battery manufacturing process.

[0053] Figure 9 A schematic diagram of the welding trajectory 400 of a welding method for preventing weld burn-through provided in an embodiment of the present invention is illustrated, as shown below. Figure 9 As shown, when the groove 310 is an annular groove, the contact surface between the groove 310 and the bottom of the housing 110 is annular, and the welding trajectory 400 between the bottom of the housing 110 and the bottom of the groove 310 is also annular, so that the welding area between the bottom of the housing 110 and the bottom of the groove 310 is as large as possible. In order to further increase the welding area between the bottom of the housing 110 and the bottom of the groove 310, the welding trajectory 400 between the bottom of the housing 110 and the bottom of the groove 310 can be a circular trajectory composed of wavy lines or a circular trajectory composed of serrated lines, etc.

[0054] Figure 10 A second flowchart illustrating a welding method for preventing weld burn-through provided by an embodiment of the present invention is shown below. Figure 10 As shown, when the material in the groove 310 is a puncture-resistant material, before performing the step of welding the manifold 300 to the core 200, the following steps are performed: drying the puncture-resistant material in the groove 310.

[0055] Since the anti-penetration material is added as a slurry containing moisture, drying can remove the moisture from the slurry so that it can be solidified in the groove 310.

[0056] According to the welding method for preventing weld penetration provided in the embodiments of the present invention, the manifold 300 is welded to the core 200 through the elastic connector 330.

[0057] According to the welding method for preventing weld penetration provided in the embodiments of the present invention, the welding position between the bottom 110 of the shell and the bottom of the tank is located at the center of the bottom of the tank, that is, the welding position is equidistant from the two sides of the bottom of the tank.

[0058] According to the welding method for preventing weld penetration provided in the embodiments of the present invention, the bottom 110 of the housing is connected to the bottom of the groove by laser welding, and the laser beam forms an acute angle with the bottom 110 of the housing.

[0059] Figure 1A schematic diagram of the front cross-sectional structure of a lithium battery provided in an embodiment of the present invention is illustrated.

[0060] Figure 2 Examples of embodiments of the present invention are provided. Figure 1 A magnified view of the structure at point A in the middle. Figure 3 Examples of embodiments of the present invention are provided. Figure 1 A magnified view of the local structure at point B, as shown below. Figure 1 , Figure 2 and Figure 3 As shown, the lithium battery includes a casing 100, a winding core 200, and a current collector 300. A cavity is formed inside the casing 100, and the winding core 200 is disposed within the cavity. The current collector 300 is also disposed within the cavity, located between the winding core 200 and the bottom 110 of the casing 100. The current collector 300 is welded to the winding core 200, and its edge has a groove 310 with its opening facing the winding core 200. A puncture-resistant pad or puncture-resistant material 320 is disposed within the groove 310. The bottom of the groove 310 abuts against the bottom 110 of the casing and is welded to it.

[0061] Figure 4 A top view of the collector disk 300 provided in an embodiment of the present invention is illustrated, as shown below. Figure 4 As shown, the manifold 300 can be circular or other shapes. The cavity formed after the manifold 300 is assembled with the bottom of the housing 110 serves as an air chamber. The manifold 300 can be made of aluminum, aluminum-nickel composite sheet, copper, copper-nickel composite sheet, or other metal materials. The housing 100 can be made of aluminum, steel, or other metal materials.

[0062] Figure 5 Examples of embodiments of the present invention are provided. Figure 4 A schematic diagram of the cross-sectional structure along section line AA. Figure 6 Examples of embodiments of the present invention are provided. Figure 5 A magnified schematic diagram of the structure at point C. Figure 7 Examples of embodiments of the present invention are provided. Figure 5 A magnified schematic diagram of the local structure at point D, as shown below. Figure 5 , Figure 6 and Figure 7As shown, in an embodiment of the present invention, the groove 310 is an annular groove, and the groove wall of the groove 310 away from the center of the current collector 300 is provided with an arc angle 340. In the prior art, the current collector 300 without an arc angle 340 is prone to interference and warping with the housing 100 with an internal R-angle, resulting in a loose fit between the current collector 300 and the housing 100, and causing poor welding during penetration welding. Poor welding will increase the internal resistance of the lithium battery and affect the safety performance of the battery. In an embodiment of the present invention, the groove wall with an arc angle 340 can better fit with the housing 100 with an internal R-angle, so as to avoid the current collector 300 warping and causing poor welding between the current collector 300 and the housing 100.

[0063] In embodiments of the present invention, the groove 310 may also be multiple arc-shaped grooves, which are evenly arranged around the outer periphery of the center of the collector plate. By setting multiple arc-shaped grooves, the welding area between the collector plate 300 and the housing 100 can be flexibly adjusted, thereby improving welding efficiency while ensuring the welding area requirements are met.

[0064] In an embodiment of the present invention, the radius of the arc angle 340 is R, where 0.35mm ≤ R ≤ 0.65mm. Preferably, the radius R of the arc angle 340 is 0.5mm.

[0065] In an embodiment of the present invention, the current collector 300 is provided with a plurality of elastic connectors 330, which are welded to the core 200. In the prior art, vibration of the core 200 can cause the current collector 300 to tear from the core 200, resulting in the current collector 300 detaching and increasing the resistance of the lithium battery. In an embodiment of the present invention, when the core 200 vibrates, the elastic connectors 330 can vibrate along with the core 200, maintaining contact with the core 200 and preventing the current collector 300 from separating from the core 200, which would increase the resistance of the lithium battery. The elastic connectors 330 can also be integrally formed with the current collector 300, further reducing the resistance of the lithium battery and improving the production efficiency of the lithium battery.

[0066] In an embodiment of the present invention, a gap 350 is formed between the elastic connector 330 and the collector plate 300, and at least one side of the elastic connector 330 is connected to the collector plate 300. In this embodiment, the elastic connector 330 is fan-shaped, so that the side of the elastic connector 330 connected to the collector plate 300 is narrower, allowing the elastic connector 330 to have a larger range of motion.

[0067] In an embodiment of the present invention, a plurality of elastic connectors 330 are equidistantly arranged around the outer periphery of the center of the collector plate 300 to ensure that the collector plate 300 is in uniform contact with the core 200 through the plurality of elastic connectors 330.

[0068] In an embodiment of the present invention, a protrusion 360 is formed at the center of the collector plate 300 on the side opposite to the winding core 200. The protrusion 360 abuts against the bottom 110 of the housing to prevent the collector plate 300 from deforming under external force. The bottom surface of the protrusion 360 may also be on the same plane as the bottom surface of the groove 310, so that both the protrusion 360 and the groove 310 abut against the bottom 110 of the housing simultaneously, preventing the collector plate 300 from deforming under external force. Preferably, the protrusion 360 may be a conical protrusion.

[0069] In an embodiment of the present invention, the outer diameter of the protrusion 360 is φ4.3mm, the height of the protrusion 360 is 0.4mm-0.6mm, and the taper of the protrusion 360 is 1:1.

[0070] In an embodiment of the present invention, the depth of the groove 310 is 0.2mm-0.4mm, and the width of the groove 310 is 0.2mm-0.5mm.

[0071] In an embodiment of the present invention, the anti-breakdown pad is a ceramic pad, and the anti-breakdown material is AT9 material. By placing a ceramic pad or AT9 material in the groove 310 of the manifold 300, laser penetration through the electrode tabs is prevented from causing a short circuit in the core 200.

[0072] In embodiments of the present invention, such as Figures 1-7 As shown, a circular manifold 300, 0.5 mm high and φ45 mm in diameter, is formed by stamping from a 0.2 mm thick sheet metal. The manifold 300 is made of T2 grade copper, and the shell 100 is made of SPCC-DCG grade steel. Six elastic connectors 330 are evenly distributed on the circular manifold 300, and the elastic connectors 330 are connected to the manifold 300 body via an external disconnection and internal connection. The protrusion 360 in the middle of the manifold 300 has an outer diameter of φ4.3 mm, a height of 0.5 mm, and a taper of 1:1. The arc angle 340 of the groove 310 away from the center of the manifold 300 is R = 0.5 mm. The groove 310 has a depth of 0.3 mm and a width of 3.5 mm.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A welding method for preventing weld burn-through, characterized in that, Includes the following steps: A puncture-resistant material is placed in the groove of the collector plate; the puncture-resistant material is a slurry containing moisture; the puncture-resistant material in the groove is then dried. The collector plate is welded to the winding core; The core and the collector plate are installed into the cavity of the housing, and the core is fixed by tooling. The bottom of the housing is welded to the bottom of the groove via the outer side of the bottom of the housing. The groove is an annular groove, and the groove wall away from the center of the collecting plate is provided with an arc corner; a protrusion is formed at the center of the collecting plate on the side away from the core, and the bottom surface of the protrusion and the bottom surface of the groove are on the same plane, so that the protrusion and the groove simultaneously abut against the bottom of the housing.

2. The welding method for preventing weld burn-through according to claim 1, characterized in that, The collector plate is welded to the core via an elastic connector.

3. The welding method for preventing weld burn-through according to claim 1, characterized in that, The welding point between the bottom of the housing and the bottom of the tank is located at the center of the bottom of the tank.

4. The welding method for preventing weld burn-through according to claim 1, characterized in that, The bottom of the housing is connected to the bottom of the groove by laser welding, and the laser beam forms an acute angle with the bottom of the housing.

5. A lithium battery based on the welding method for preventing weld burn-through as described in any one of claims 1 to 4, characterized in that, include: The shell has an internal cavity. The core is disposed within the cavity; A collector plate is disposed within the cavity and located between the core and the bottom of the housing. The collector plate is welded to the core. The edge of the collector plate forms a groove with its opening facing the core. The groove is filled with a puncture-resistant material. The bottom of the groove abuts against the bottom of the housing and is welded to the bottom of the housing. The groove is an annular groove, and the groove wall away from the center of the collector plate has a rounded corner. The center of the collector plate opposite to the winding core has a protrusion, and the bottom surface of the protrusion and the bottom surface of the groove are on the same plane, so that the protrusion and the groove simultaneously abut against the bottom of the housing.

6. The lithium battery according to claim 5, characterized in that, The radius of the arc angle is R, where 0.35mm ≤ R ≤ 0.65mm.

7. The lithium battery according to claim 5, characterized in that, The collector plate is provided with multiple elastic connectors, which are welded to the core; a gap is formed between the elastic connectors and the collector plate, and at least one side of the elastic connector is connected to the collector plate; the multiple elastic connectors are equidistantly arranged around the outer periphery of the center of the collector plate.

8. The lithium battery according to any one of claims 5 to 7, characterized in that, The outer diameter of the protrusion is 4.3mm, the height of the protrusion is 0.4mm-0.6mm, and the taper of the protrusion is 1:

1.

9. The lithium battery according to any one of claims 5 to 7, characterized in that, The groove has a depth of 0.2mm-0.4mm and a width of 0.2mm-0.5mm; the puncture-resistant material is AT9 material.

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