Battery tab welding method and equipment

Abstract

The invention provides a battery tab welding method and equipment. The battery tab welding method comprises the following steps: performing ultrasonic pre-welding on a battery tab to form a semi-finished tab; adapters are configured, the semi-finished product tab is clamped between the two adapters, and the adapters are attached to the semi-finished product tab to form a tab to be welded; placing the tab to be welded in a vacuum environment; and projecting a light spot of a laser beam to the adapter so as to weld the adapter and the semi-finished tab. According to the method, annular laser is used for welding the tab in the vacuum environment, protective gas does not need to be added, meanwhile, gas in a molten pool and a key hole can be rapidly exhausted, and the probability that air holes exist in the tab after welding can be greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery tab welding method and equipment. Background Art

[0002] As a key part of the battery cell, the tab conducts current and connects the core. The commonly used welding method is ultrasonic welding of the tab and the battery cover adapter. However, this welding method is prone to cold welding when facing thicker tabs, such as tabs with more than 60 layers. At the same time, since ultrasonic welding vibrates the tab and the adapter at high frequency, the edge area of ​​the tab welding is prone to fracture or reduced toughness, so laser welding is currently used more often.

[0003] However, traditional fiber laser welding of the tabs has problems such as large spatter, severe oxidation, many internal pores, and poor surface quality. Spatter and pores are the most concerned issues in the battery cell processing process. If the spatter remains on the tab or falls directly into the winding core, it will cause the battery performance to decline. In severe cases, it will cause problems such as short circuits, which seriously threaten the safety of the battery. Since the tabs in the battery cell play the role of connecting the cover plate to transmit current, if there are too many or too large internal pores after the tabs are welded, the internal resistance of the battery cell will be too large when the current is over, causing overheating. At the same time, the strength is reduced, resulting in the tabs or the roots of the tabs breaking, which is also very harmful.

[0004] At the same time, laser welding is prone to generate dust and form photoplastic plume, which is composed of plasma near the keyhole of the molten pool at the bottom and condensed metal vapor particles at the top. For the above problems, the current solution is to apply shielding gas, but shielding gas cannot completely solve the oxidation problem. At the same time, the spatter problem cannot be solved and may even be more serious, generating larger plasma and affecting the laser penetration. Summary of the invention

[0005] In view of the deficiencies in the prior art, the first object of the present invention is to provide a battery tab welding method, which uses a circular laser to weld the tabs in a vacuum environment, thereby effectively ensuring the welding quality of the tabs.

[0006] The second object of the present invention is to provide a battery tab welding machine device, which has a simple structure and is convenient for quickly providing a vacuum environment for tab welding.

[0007] The embodiments of the present invention are implemented by the following technical solutions:

[0008] A battery tab welding method comprises the following steps:

[0009] Ultrasonic pre-welding of the battery tabs to form semi-finished tabs;

[0010] Arrange an adapter, clamp the semi-finished pole lug between two adapters, and make the adapter and the semi-finished pole lug fit together to form a pole lug to be welded;

[0011] Placing the electrode lug to be welded in a vacuum environment;

[0012] The spot of the laser beam is projected onto the adapter to weld the adapter and the semi-finished tab.

[0013] According to a preferred embodiment, the two adapters are arranged in parallel.

[0014] According to a preferred embodiment, the thickness of the adapter is 0.1 mm-0.3 mm.

[0015] According to a preferred embodiment, the light spot of the laser beam is a single-mode annular light spot, including an inner light spot and an annular light spot arranged outside the inner light spot.

[0016] According to a preferred embodiment, the power of the inner light spot is 200W-1000W.

[0017] According to a preferred embodiment, the power of the annular spot is 300W-1000W.

[0018] According to a preferred embodiment, the welding speed of the laser beam spot on the adapter is 100 mm / s-500 mm / s.

[0019] According to a preferred embodiment, the welding track of the laser beam spot on the adapter is spiral, elliptical or figure 8-shaped.

[0020] A battery tab welding device, used to perform the aforementioned battery tab welding method, comprises a vacuum box, wherein a jig for fixing an adapter and a semi-finished tab is arranged in the vacuum box, welding holes and exhaust holes are arranged on the side wall of the vacuum box, a quartz glass cover is mounted on the welding hole, and the exhaust hole is connected to a vacuum pump; the battery tab welding device also comprises a galvanometer welding head for transmitting a laser beam, wherein the laser beam passes through the quartz glass cover to the adapter and the semi-finished tab on the jig.

[0021] According to a preferred embodiment, the jig includes a base plate, on which a battery support and a welding support are arranged, the battery support is used to support the winding core, and the welding support is used to support the adapter and the semi-finished pole ear; the jig also includes a pressure block adjustably arranged on the base plate, the pressure block corresponds to the welding support, and can approach or move away from the welding support in the longitudinal direction, and a welding notch is penetrated on the pressure block, and the laser beam passes through the welding notch to the adapter and the semi-finished pole ear.

[0022] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0023] The present invention uses an annular laser to weld the pole ear in a vacuum environment without adding a protective gas, and the gas in the molten pool and the keyhole can be quickly discharged, which can greatly reduce the probability of having pores inside the pole ear after welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 A flow chart of a battery tab welding method provided by an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the assembly structure of the adapter and the semi-finished tab provided in an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the three-dimensional structure of a vacuum box provided in an embodiment of the present invention;

[0028] Figure 4 A schematic diagram of the three-dimensional structure of the jig provided in an embodiment of the present invention after being assembled with a winding core.

[0029] Icons: 1. winding core; 10. pole ear to be welded; 11. semi-finished pole ear; 12. adapter; 2. vacuum box; 21. box body; 211. cover plate; 22. box cover; 221. quartz glass cover; 23. fixture; 231. bottom plate; 232. battery support; 233. welding support; 234. clamping handle; 235. pressing block; 2351. welding notch; 236. longitudinal plate; 2361. first adapter plate; 2362. driving member; 237. second adapter plate; 2371. limit plate; 2372. guide shaft; 238. adapter block; 239. buffer spring. DETAILED DESCRIPTION

[0030] For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0033] Please refer to Figures 1 to 4 , a battery tab welding method, comprising the following steps:

[0034] Step S1: ultrasonically pre-welding the battery tabs to form semi-finished tabs 11;

[0035] Step S2: configuring the adapter 12, clamping the semi-finished pole lug 11 between two adapters 12, and making the adapter 12 and the semi-finished pole lug 11 fit together to form the pole lug 10 to be welded;

[0036] Step S3: placing the electrode tab 10 to be welded in a vacuum environment;

[0037] Step S4 : projecting a spot of the laser beam onto the adapter 12 to weld the adapter 12 and the semi-finished tab 11 .

[0038] In this embodiment, the battery tabs are composed of layers of 8μm-12μm aluminum foil, and the battery tabs are pre-welded by ultrasonic welding to form an integral semi-finished tab 11, which facilitates the smooth clamping and welding of the battery tabs in the subsequent laser welding process. Figure 2 As shown, the adapter 12 is a battery cover adapter, including an upper adapter and a lower adapter, and the semi-finished pole lug 11 is located between the upper adapter and the lower adapter. In this embodiment, the semi-finished pole lug 11 and the upper and lower adapters are welded into a whole by laser. In step S3, preferably, the winding core 1 and the semi-finished pole lug 11 and the upper and lower adapters are completely placed in a vacuum environment, so that the formation of the vacuum environment can be facilitated and the sealing can be ensured. Preferably, the air pressure of the vacuum environment is at least 1OPa. When laser welding is used in a vacuum environment, there is no need to add protective gas. The vacuum environment can effectively reduce impurities and gases in the space of the pole lug welding area, thereby reducing the probability of pores in the pole lug during welding. At the same time, the gas in the molten pool and the keyhole can be quickly discharged, which can greatly reduce the probability of pores inside the pole lug after welding.

[0039] In this embodiment, the two adapters 12 are arranged in parallel, that is, the upper adapter piece and the lower adapter piece are arranged in parallel.

[0040] Optionally, the adapter 12 has a thickness of 0.1 mm-0.3 mm.

[0041] Optionally, the light spot of the laser beam is a single-mode annular light spot, including an inner light spot and an annular light spot arranged outside the inner light spot.

[0042] Specifically, the power of the inner spot is 200W-1000W. Preferably, the power of the inner spot is 200W-400W. The power of the ring spot is 300W-1000W. Preferably, the power of the ring spot is 300W-600W. The welding speed of the laser beam spot on the adapter 12 is 100mm / s-500mm / s. Preferably, the welding speed of the laser beam spot on the adapter 12 is 100mm / s-300mm / s.

[0043] Furthermore, the welding trajectory of the laser beam spot on the adapter 12 is spiral, elliptical or 8-shaped. In the present embodiment, preferably, the welding trajectory of the laser beam spot on the adapter 12 is spiral. The swing amplitude of the galvanometer is 0.1mm-0.4mm. In the present embodiment, the inner spot is used to form a deeper melting depth to form the central area of ​​the molten pool, and the ring spot is used to reduce the temperature gradient at the edge of the molten pool to reduce spatter. Welding is performed by combining the inner spot and the ring spot, and in conjunction with the vacuum welding environment, it is possible to ensure the melting depth, reduce welding spatter, reduce the pores inside the tab, and ensure the welding quality of the battery tab.

[0044] like Figure 3 and Figure 4 As shown, a battery tab welding device is used to perform the above-mentioned battery tab welding method, including a vacuum box 2, wherein a fixture 23 for fixing the adapter 12 and the semi-finished tab 11 is arranged in the vacuum box 2, and welding holes and exhaust holes are arranged on the side wall of the vacuum box 2, and a quartz glass cover 221 is installed on the welding hole, and the exhaust hole is connected to a vacuum pump; the battery tab welding device also includes a galvanometer welding head (not shown in the figure) for transmitting a laser beam, and the laser beam passes through the quartz glass cover 221 to the adapter 12 and the semi-finished tab 11 on the fixture 23. Figure 3As shown, the vacuum box 2 includes a box body 21 and a box cover 22, a quartz glass cover 221 is arranged on the box cover 22, and a sealing strip is arranged between the box cover 22 and the box body 21 to achieve sealing. In this embodiment, the box cover 22 is detachably assembled to the box body 21 by bolts or screws. The box body 21 is a square box, and a material taking port is opened on one side of the box body 21, and a cover plate 211 for covering the material taking port is arranged on the side. Further, the cover plate 211 and the side of the box body 21 are sealed by a sealing strip.

[0045] like Figure 4 As shown, the jig 23 includes a base plate 231, on which a battery support 232 and a welding support 233 are arranged, the battery support 232 is used to support the winding core 1, and the welding support 233 is used to support the adapter 12 and the semi-finished pole lug 11; the jig 23 also includes a pressing block 235 adjustably arranged on the base plate 231, the pressing block 235 corresponds to the welding support 233, and can approach or move away from the welding support 233 in the longitudinal direction, and a welding notch 2351 is penetrated on the pressing block 235, and the laser beam passes through the welding notch 2351 to the adapter 12 and the semi-finished pole lug 11. When in use, the winding core 1 is placed on the battery support 232 and is clamped and fixed by a clamping handle 234 installed on the battery support 232. At this time, the adapter 12 and the semi-finished pole ear 11 formed by pre-welding are overlapped on the welding support 233 and are clamped and fixed by the pressing block 235. The laser beam passing through the quartz glass cover 221 passes through the welding notch 2351 and completes the welding of the adapter 12 and the semi-finished pole ear 11 within the area of ​​the welding notch 2351.

[0046] Specifically, a longitudinal plate 236 is mounted on the bottom plate 231, and a first adapter plate 2361 is slidably mounted on the longitudinal plate 236 toward one side of the welding support 233, and the pressing block 235 is mounted on the first adapter plate 2361. A driving member 2362 for driving the first adapter plate 2361 to move is configured on the longitudinal plate 236. Optionally, the driving member 2362 is an electric cylinder or a pneumatic cylinder. In some embodiments, in order to make the structure of the fixture 23 compact, the first adapter plate 2361 is slidably mounted on the cylinder body of the electric cylinder or the pneumatic cylinder.

[0047] Furthermore, a second adapter plate 237 is fixedly mounted on the first adapter plate 2361, and a limiting plate 2371 is arranged on the second adapter plate 237. A side of the second adapter plate 237 facing the welding support 233 is equipped with an adapter block 238 through a slide rail slider assembly. The pressing block 235 is fixedly mounted on the adapter block 238. A guide shaft 2372 is arranged on the adapter block 238. The guide shaft 2372 passes through the limiting plate 2371 and is slidably connected thereto. A buffer spring 239 is arranged on the outer sleeve of the guide shaft 2372. The buffer spring 239 is located between the limiting plate 2371 and the adapter block 238. Figure 4 As shown, the adapter block 238 is located below the limit plate 2371. When in use, the driving member 2362 drives the first adapter plate 2361 to move longitudinally, so that the adapter block 238 assembled on the second adapter plate 237 moves longitudinally, and when the pressing block 235 abuts against the adapter 12, the pressing block 235, i.e., the adapter block 238, is forced to compress the buffer spring 239 upward longitudinally, so as to achieve flexible abutment between the pressing block 235 and the adapter 12, thereby preventing the adapter 12 and the semi-finished tab 11 from being crushed.

[0048] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A battery tab welding method, characterized in that: The steps include: Ultrasonic pre-welding of the battery tabs to form semi-finished tabs; Arrange an adapter, clamp the semi-finished pole lug between two adapters, and make the adapter and the semi-finished pole lug fit together to form a pole lug to be welded; Placing the electrode lug to be welded in a vacuum environment; The spot of the laser beam is projected onto the adapter to weld the adapter and the semi-finished tab.

2. The battery tab welding method according to claim 1, characterized in that: The two adapters are arranged in parallel.

3. The battery tab welding method according to claim 1, characterized in that: The thickness of the adapter is 0.1 mm-0.3 mm.

4. The battery tab welding method according to claim 1, characterized in that: The light spot of the laser beam is a single-mode annular light spot, including an inner light spot and an annular light spot arranged outside the inner light spot.

5. The battery tab welding method according to claim 4, characterized in that: The power of the inner light spot is 200W-1000W.

6. The battery tab welding method according to claim 4, characterized in that: The power of the annular light spot is 300W-1000W.

7. The battery tab welding method according to claim 1, characterized in that: The welding speed of the laser beam spot on the adapter is 100 mm / s-500 mm / s.

8. The battery tab welding method according to claim 1, characterized in that: The welding track of the laser beam spot on the adapter is spiral, elliptical or figure 8.

9. A battery tab welding device, used to perform the battery tab welding method according to any one of claims 1 to 8, characterized in that: The battery tab welding equipment comprises a vacuum box, wherein a jig for fixing an adapter and a semi-finished tab is arranged in the vacuum box, a welding hole and an exhaust hole are arranged on the side wall of the vacuum box, a quartz glass cover is mounted on the welding hole, and the exhaust hole is connected to a vacuum pump; the battery tab welding equipment also comprises a galvanometer welding head for transmitting a laser beam, wherein the laser beam passes through the quartz glass cover to the adapter and the semi-finished tab on the jig.

10. The battery tab welding equipment according to claim 9, characterized in that: The jig comprises a bottom plate, on which a battery support and a welding support are arranged, wherein the battery support is used to support the winding core, and the welding support is used to support the adapter and the semi-finished lug; The jig also includes a pressing block adjustably arranged on the bottom plate, the pressing block corresponds to the welding support and can be moved closer to or farther away from the welding support in the longitudinal direction, a welding notch is penetrated through the pressing block, and the laser beam passes through the welding notch to the adapter and the semi-finished pole ear.

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