CN114833443A - Welding method of multilayer tab - Google Patents

Welding method of multilayer tab Download PDF

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Publication number
CN114833443A
CN114833443A CN202210377662.5A CN202210377662A CN114833443A CN 114833443 A CN114833443 A CN 114833443A CN 202210377662 A CN202210377662 A CN 202210377662A CN 114833443 A CN114833443 A CN 114833443A
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China
Prior art keywords
welding
tab
laser
area
filling
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CN202210377662.5A
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Chinese (zh)
Inventor
张�荣
冯伟贤
周华
刘望
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Shenzhen Hymson Laser Intelligent Equipment Co Ltd
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Shenzhen Hymson Laser Intelligent Equipment Co Ltd
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Priority to CN202210377662.5A priority Critical patent/CN114833443A/en
Publication of CN114833443A publication Critical patent/CN114833443A/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/20Bonding
    • B23K26/21Bonding by welding
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Abstract

The invention relates to a welding method of a multilayer tab. When a plurality of layers of tabs and adapter plates are welded, the tabs and the adapter plates are fixed firstly, a welding area is determined, and then the welding area is welded by laser, wherein the transmission mode of the laser is a continuous mode. In the welding method of the multilayer tab, the welding area is determined firstly, and then the welding area is welded by laser, so that tab fracture at the edge of a welding line can be reduced, the excessive melting of the welding line at the initial and final positions can be avoided, and the quality of the welding line is ensured. In addition, the heat input amount can be reduced, the welding stability is improved, the process adaptability of the welding process to foreign matters such as aluminum powder particles can be improved, and the product yield is improved. The transmission mode of laser is continuous mode, and output power is lower relatively, can last the output in specific time frame, has guaranteed the even continuity of welding seam, has promoted the welding seam quality.

Description

Welding method of multilayer tab
Technical Field
The invention belongs to the technical field of battery preparation, and particularly relates to a welding method of a multilayer tab.
Background
The battery contains a battery core inside, and the structure generally comprises a positive electrode, a negative electrode, a diaphragm and electrolyte. The tab is a metal conductor which leads out the positive and negative electrodes from the battery core and is a contact point when the battery is charged and discharged. The tab is generally small in area, thin in thickness, and easily broken. Therefore, the positive electrode tab, the negative electrode tab and the top cover of the battery shell are generally connected through the adapter sheet.
Currently, in the lithium battery manufacturing process, the welding between the tab and the adapter sheet is realized by ultrasonic welding. Because ultrasonic welding belongs to contact welding, equipment needs to be in direct contact with the pole lug and the adapter plate in the welding process, and a certain space is needed for placing the welding seat. Therefore, the battery using the ultrasonic welding process needs to design a relatively complex adapter plate structure, and after the ultrasonic welding is completed, the adapter plate of the welding seam part is folded. This increases the complexity of the cell structure, increases the process steps of the manufacturing process, and also increases the risk of defects in the entire line. Meanwhile, the adoption of ultrasonic welding after the thickness dimension of the battery core exceeds a certain critical dimension can lead to the exponential rise of poor welding, and the waste of the manufacturing cost of the product battery is caused.
Therefore, in order to realize reliable connection between the multi-layer tab and the interposer and solve the problem of fracture of the foil layer at the edge of the weld joint at the aluminum end, a new welding method needs to be developed.
Disclosure of Invention
The present invention is directed to solving at least one of the above problems in the prior art. Therefore, the invention provides a welding method of a multilayer tab, which adopts laser to weld a welding area, wherein the transmission mode of the laser is a continuous mode, solves the problems of ultrasonic welding of the multilayer tab and an adapter plate, and is suitable for welding of the multilayer tab and the adapter plate.
The invention provides a welding method of a multilayer tab, which comprises the following steps:
s1: fixing a plurality of layers of tabs and adapter plates, and determining a welding area;
s2: welding the welding area by adopting laser;
the transmission mode of the laser is a continuous mode;
the number of layers of the multilayer tab is more than 20.
The invention relates to a technical scheme of a welding method of a multilayer tab, which at least has the following beneficial effects:
the invention relates to a welding method of a multilayer tab, which is a welding method between the multilayer tab and an adapter plate. The number of the layers of the multilayer tab is more than 20, and the multilayer tab is prewelded. When a plurality of layers of tabs and the adapter plate are welded, the plurality of layers of tabs and the adapter plate are fixed firstly, a welding area is determined, then the welding area is welded by adopting laser, wherein the transmission mode of the laser is a continuous mode. In the welding method of the multilayer pole ear, the welding area is determined firstly, and then the welding area is welded by adopting laser, so that the pole ear fracture at the edge of the welding line can be reduced, the over-fusion of the welding line at the initial and ending positions can be avoided, and the welding line quality is ensured. In addition, the heat input amount can be reduced, the welding stability is improved, the process adaptability of the welding process to foreign matters such as aluminum powder particles can be improved, and the product yield is improved. The transmission mode of laser is continuous mode, and output power is lower relatively, can last the output in specific time frame, has guaranteed the even continuity of welding seam, has promoted the welding seam quality.
According to the welding method of the multilayer tab, the welding area is determined firstly, and then the welding area is welded by laser, so that the problem of low welding yield in the existing process after the thickness and the size of the battery cell are increased is solved, and the problem of more complex battery structure is avoided. In addition, under the volume of the laser welding equipment, the welding equipment does not need to be arranged in a large space, the process flow is simple, and the adverse risk is integrally reduced.
The invention relates to a welding method of a multilayer tab, belonging to penetration welding in laser welding. The focal point is positioned on the contact surface of the multilayer pole lug and the adapter plate by adjusting the focal point position of the laser, so that the multilayer pole lug and the adapter plate are welded.
According to some embodiments of the invention, the laser is a continuous fiber laser.
According to some embodiments of the invention, the multi-layer tab comprises an aluminum tab and a copper tab.
The aluminum tab is a multi-layer aluminum tab formed by stacking a plurality of single-layer aluminum tabs.
The copper lug is a multilayer copper lug formed by stacking a plurality of single-layer copper lugs.
Usually, the anode material is aluminum and the cathode material is copper, so that the aluminum tab is connected with the anode and the copper tab is connected with the cathode, and the materials are kept consistent.
According to some embodiments of the present invention, the material of the interposer is the same as the material of the tab.
The welding method of the multilayer tab is particularly suitable for square-shell batteries and blade batteries.
The square-shell battery is a square lithium battery, generally an aluminum-shell or steel-shell square battery, the popularization rate of the square battery is high, along with the rise of automobile power batteries in recent years, the contradiction between the automobile endurance mileage and the battery capacity is increasingly remarkable, and domestic power battery manufacturers mostly adopt the aluminum-shell square battery with higher battery energy density as the main part, because the square battery has a simpler structure, the square battery is not like a cylindrical battery which adopts stainless steel with higher strength as a shell and accessories such as an explosion-proof safety valve, the weight of the whole accessory is lighter, and the relative energy density is higher. The square battery adopts two different processes of winding and laminating.
The blade battery has a new structural design, and modules can be skipped when the blade battery is grouped, so that the volume utilization rate is greatly improved, and finally the design goal of filling more battery cores in the same space is achieved.
In the soft package battery, the tab thickness is usually 1mm or more. Compared with a soft package battery, the square-shell battery and the blade battery have the advantages that the electrode lug is thinner, smaller in area and easier to break. Therefore, the welding method of the multilayer tab is particularly suitable for square-shell batteries and blade batteries.
According to some embodiments of the invention, the single-layer tab in the multi-layer tab has a thickness of 6-12 μm.
According to some embodiments of the invention, the single-layer aluminum tab of the multi-layer tab has a thickness of 6 to 12 μm.
According to some embodiments of the invention, the single-layer copper tab has a thickness of 6 μm to 10 μm.
According to some embodiments of the invention, before welding, a tab fixture is used for clamping and welding positioning of the multilayer tabs, and the to-be-welded area of the multilayer tabs is located in the middle of the to-be-welded area of the welding fixture.
According to some embodiments of the invention, before welding, the initial position and the ending position of weld filling are determined in advance, and the initial position and the ending position of a welding area are in corresponding relation with time, so that a high-quality weld is formed conveniently.
According to some embodiments of the invention, the welding zone is rectangular in shape and has a size of (1mm to 3mm) × (20mm to 30 mm).
The welding area is rectangular and has the size of (1-3 mm) × (20-30 mm), so that the breakage of the tabs at the edge of the welding line can be reduced, and the over-melting of the welding line at the initial and final positions can be avoided.
According to some embodiments of the invention, the welding area is in the middle position of the tab, so that the multi-layer tab and the adapter plate are stressed more uniformly, and the problem of tab fracture is further reduced.
According to some embodiments of the invention, the welding speed is 200mm/S to 500mm/S in step S2.
According to some embodiments of the invention, the welding speed is 250mm/S to 500mm/S in step S2.
According to some embodiments of the invention, the welding speed is 300mm/S to 500mm/S in step S2.
According to some embodiments of the invention, the welding speed is 350mm/S to 500mm/S in step S2.
According to some embodiments of the present invention, in step S2, the filling mode is galvanometer filling.
The laser scanner is also called laser galvanometer and consists of an X-Y optical scanning head, an electronic driving amplifier and an optical reflecting lens.
The filling mode is vibrating mirror filling, the uniformity and the appearance of the welding line can be improved, and the quality of the welding line is finally improved.
The galvanometer can swing, so that a swing track is designed in advance.
According to some embodiments of the invention, during welding, a galvanometer filling mode is adopted for welding, the galvanometer is used for adjusting the light path direction of the laser beam 3, a welding area is set in galvanometer control software, and a welding drawing file is established according to requirements.
According to some embodiments of the invention, the laser beam path filled by the galvanometer is in an arcuate or Z-shaped orientation.
The laser light path that the galvanometer was filled is bow-shaped trend or Z shape trend, and the first aspect can promote the welding seam outward appearance, and the second aspect can promote the welding seam quality, reduces welded defective rate. The third aspect may have better penetration. The fourth aspect can improve the stability of the weld.
Compared with unidirectional filling, the arc-shaped trend or Z-shaped trend has better weld appearance and less tab fracture.
According to some embodiments of the invention, the filling pitch of the galvanometer filling is between 0.05mm and 0.1 mm.
The filling interval is 0.05 mm-0.1 mm, so that the appearance of the welding line is uniform and not rough, and the quality of the welding line is improved. Too small a filling distance results in a long time and reduced efficiency.
According to some embodiments of the invention, in the method for welding the multilayer tab, the gradually changed welding parameter setting is adopted, the wave-shaped climbing time and the welding speed acceleration time are prolonged at the initial position and the ending position of the weld filling, and the welding is carried out at the focus, so that the tab fracture at the edge of the weld can be reduced, and the over-melting of the weld at the initial position and the ending position can be avoided. The welding seam quality is guaranteed, the heat input is reduced, the welding stability is improved, meanwhile, the process adaptability of the welding process to foreign matters such as aluminum powder particles can be improved, and the product yield is improved.
According to some embodiments of the invention, the laser power is 300W to 3000W during welding.
According to some embodiments of the invention, the laser power is 400W to 3000W during welding.
According to some embodiments of the invention, the laser power is between 1000W and 2000W during welding.
According to some embodiments of the invention, the laser has a defocus amount of-1.5 to 1.5 mm.
According to some embodiments of the present invention, a protective gas is supplied to the welding area during welding, whereby the welding area is prevented from being oxidized during welding.
According to some embodiments of the invention, the protective gas is delivered by annular side blowing during welding.
According to some embodiments of the invention, the protective gas is nitrogen during welding.
According to some embodiments of the invention, the flow rate of the protective gas during welding is between 10L/min and 20L/min.
Through the optimization and adjustment of laser parameters, air flow, filling modes, filling intervals and the like, the welding seam with uniform appearance is obtained.
Drawings
FIG. 1 is a schematic view of the welding process of the present invention.
FIG. 2 is the appearance of the weld of example 1.
FIG. 3 is the appearance of the weld of example 2.
FIG. 4 is the appearance of the weld of example 3.
FIG. 5 is the appearance of the weld of example 4.
FIG. 6 is the appearance of the weld of example 5.
FIG. 7 is the appearance of the weld of example 6.
FIG. 8 is the appearance of the weld of example 7.
FIG. 9 is the appearance of the weld of example 8.
Fig. 10 is the appearance of the weld of comparative example 1.
Fig. 11 is the appearance of the weld of comparative example 2.
Fig. 12 is the appearance of the weld of comparative example 3.
Fig. 13 is a phase diagram of the multi-layer tab of example 1 welded to an interposer at 50 x magnification.
Fig. 14 is a partial 150-fold enlarged view of the interface between the weld pool and tab of example 1.
Fig. 15 is a phase diagram of the multi-layer tab of comparative example 1 at 50 x magnification after welding to an interposer.
Fig. 16 is a partial 150-fold enlarged view of the weld pool and tab interface location of comparative example 1.
Reference numerals:
100: pre-welding a plurality of layers of tabs;
200: a patch;
300: a welding area;
400: a laser beam;
500: and (5) battery cores.
Detailed Description
The following are specific examples of the present invention, and the technical solutions of the present invention will be further described with reference to the examples, but the present invention is not limited to the examples.
In some embodiments of the present invention, a method for welding a multi-layer tab is provided, which includes the following steps:
s1: fixing a plurality of layers of pole lugs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
wherein, the transmission mode of the laser is a continuous mode;
the number of layers of the multi-layer tab is more than 20.
It can be understood that the welding method of the multi-layer tab of the present invention refers to a welding method between the multi-layer tab and the adaptor plate. The number of the layers of the multilayer tab is more than 20, and the multilayer tab is prewelded. When a plurality of layers of tabs and adapter plates are welded, the tabs and the adapter plates are fixed firstly, a welding area is determined, and then the welding area is welded by laser, wherein the transmission mode of the laser is a continuous mode. In the welding method of the multilayer tab, the welding area is determined firstly, and then the welding area is welded by laser, so that tab fracture at the edge of a welding line can be reduced, the excessive melting of the welding line at the initial and final positions can be avoided, and the quality of the welding line is ensured. In addition, the heat input amount can be reduced, the welding stability is improved, the process adaptability of the welding process to foreign matters such as aluminum powder particles can be improved, and the product yield is improved. The transmission mode of laser is continuous mode, and output power is lower relatively, can last the output in specific time frame, has guaranteed the even continuity of welding seam, has promoted the welding seam quality.
It can be further understood that in the welding method of the multilayer tab, the welding area is determined firstly, and then the welding area is welded by laser, so that the problem of low welding yield in the prior art after the thickness size of the battery cell is increased is solved, and the problem of more complex battery structure is avoided. In addition, under the volume of the laser welding equipment, the welding equipment does not need to be arranged in a large space, the process flow is simple, and the adverse risk is integrally reduced.
In some embodiments of the invention, the laser is a continuous fiber laser.
In some embodiments of the invention, the multi-layer tab includes an aluminum tab and a copper tab.
Wherein, the aluminium utmost point ear is the multilayer aluminium utmost point ear that a plurality of individual layer aluminium utmost point ears pile up and form.
The copper lug is a multilayer copper lug formed by stacking a plurality of single-layer copper lugs.
Generally, the cathode material is aluminum and the anode material is copper, so the aluminum tab is connected with the cathode and the copper tab is connected with the anode, and the materials are kept consistent.
In some embodiments of the present invention, the material of the interposer is the same as the material of the tab.
It can be understood that the welding method of the multi-layer tab of the invention is particularly suitable for square-shell batteries and blade batteries.
The square-shell battery is a square lithium battery, generally an aluminum-shell or steel-shell square battery, the popularization rate of the square battery is high, along with the rise of automobile power batteries in recent years, the contradiction between the automobile endurance mileage and the battery capacity is increasingly remarkable, and domestic power battery manufacturers mostly adopt the aluminum-shell square battery with higher battery energy density as the main part, because the square battery has a simpler structure, the square battery is not like a cylindrical battery which adopts stainless steel with higher strength as a shell and accessories such as an explosion-proof safety valve, the weight of the whole accessory is lighter, and the relative energy density is higher. The square battery adopts two different processes of winding and laminating.
The blade battery has a new structural design, and modules can be skipped when the blade battery is grouped, so that the volume utilization rate is greatly improved, and finally the design goal of filling more battery cores in the same space is achieved.
In the soft package battery, the tab thickness is usually 1mm or more. Compared with a soft package battery, the square-shell battery and the blade battery have the advantages that the electrode lug is thinner, smaller in area and easier to break. Therefore, the welding method of the multilayer tab is particularly suitable for square-shell batteries and blade batteries.
In some embodiments of the present invention, the single-layer tab has a thickness of 6 to 12 μm in the multi-layer tab.
In some embodiments of the present invention, the single-layer aluminum tab has a thickness of 6 to 12 μm in the multi-layer tab.
In some embodiments of the present invention, the single-layer copper tab has a thickness of 6 μm to 10 μm in the multi-layer tab.
In some embodiments of the invention, before welding, a tab fixture is used for clamping and welding and positioning the multilayer tabs, and the to-be-welded area of the multilayer tabs is located in the middle of the to-be-welded area of the welding fixture.
In some embodiments of the invention, before welding, the initial position and the ending position of the weld filling are determined in advance, and the initial position and the ending position of the welding area are in corresponding relation with time, so that a high-quality weld is formed conveniently.
In some embodiments of the invention, the weld region is rectangular in shape and has a size of (1mm to 3mm) × (20mm to 30 mm).
It can be understood that the welding area is rectangular, and the size is (1 mm-3 mm) × (20 mm-30 mm), so that the breakage of the tab at the edge of the welding line can be reduced, and the over-melting of the welding line at the initial and final positions can be avoided.
The welding area is arranged in the middle of the tab, so that the multi-layer tab and the adapter plate are stressed more uniformly, and the problem of tab fracture is further reduced.
In some embodiments of the present invention, the welding speed is 200mm/S to 500mm/S in step S2.
In other embodiments of the present invention, the welding speed is 250mm/S to 500mm/S in step S2.
In other embodiments of the present invention, the welding speed is 300mm/S to 500mm/S in step S2.
In other embodiments of the present invention, the welding speed is 350mm/S to 500mm/S in step S2.
In some embodiments of the present invention, in step S2, the filling mode is galvanometer filling.
It is understood that the galvanometer is a scanning galvanometer used in the laser industry, and a laser scanner, also called a laser galvanometer, is composed of an X-Y optical scanning head, an electronic driving amplifier and an optical reflecting lens.
The filling mode is vibrating mirror filling, the uniformity and the appearance of the welding line can be improved, and the quality of the welding line is finally improved.
The galvanometer can swing, so that a swing track is designed in advance.
In some embodiments of the present invention, a galvanometer filling mode is adopted for welding, the galvanometer is used for adjusting the light path direction of the laser beam 3, a welding area is set in galvanometer control software, and a welding drawing file is established according to requirements.
In some embodiments of the present invention, the laser path filled by the galvanometer is in an arcuate or Z-shaped orientation.
It can be understood that the laser light path that the galvanometer was filled is bow-shaped trend or Z shape trend, and the first aspect can promote the welding seam outward appearance, and the second aspect can promote the welding seam quality, reduces welded defective rate. The third aspect may have better penetration. The fourth aspect can improve the stability of the weld.
In some embodiments of the invention, the filling pitch of the galvanometer filling is between 0.05mm and 0.1 mm.
It can be understood that the filling distance is 0.05 mm-0.1 mm, so that the appearance of the welding seam is uniform and not rough, and the quality of the welding seam is improved. Too small a filling distance results in a long time and reduced efficiency. Too large a filling distance results in poor appearance quality and unsatisfactory fracture properties.
In some embodiments of the invention, by adopting gradual change welding parameter setting, waveform climbing time and welding speed acceleration time are prolonged at the initial position and the ending position of weld filling, and welding is carried out at a focus, so that not only can the breakage of a tab at the edge of a weld joint be reduced, but also the over-melting of the weld joint at the initial position and the ending position can be avoided. The welding seam quality is guaranteed, the heat input is reduced, the welding stability is improved, meanwhile, the process adaptability of the welding process to foreign matters such as aluminum powder particles can be improved, and the product yield is improved.
And the waveform climbing time and the welding speed acceleration time are prolonged at the initial position and the ending position of the weld filling, namely the laser power is gradually increased from 0 to 100 percent in the welding process and then is gradually reduced until the welding is finished.
In some embodiments of the present invention, the laser power is 300W to 3000W during welding.
In other embodiments of the present invention, the laser power is 400W to 3000W during welding.
In other embodiments of the present invention, the laser power is between 1000W and 2000W during welding.
It will be appreciated that the power of the laser is related to the number of layers of the welded multi-layer tab. The more the layer number is, the higher the corresponding laser power is; conversely, the smaller the number of layers, the lower the corresponding laser power. When the number of the multi-layer tab is 50, the welding power is about 300W.
In some embodiments of the present invention, the defocusing amount of the laser is-1.5 to 1.5 mm.
In some embodiments of the invention, a protective gas is supplied to the weld zone during welding, whereby oxidation of the weld zone during welding can be prevented.
In some embodiments of the invention, the protective gas is delivered by circular side blowing during welding.
In some embodiments of the invention, the protective gas is nitrogen during welding.
In some embodiments of the invention, the flow rate of the protective gas during welding is between 10L/min and 20L/min.
Further, the welding process of the present invention may be understood with reference to fig. 1. In fig. 1, 100 is a pre-welded multi-layer tab, 200 is an interposer, 300 is a welding area, 400 is a laser beam, and 500 is a cell.
The technical solution of the present invention will be understood by referring to the specific examples.
In the following examples and comparative examples, the multi-layered tab was a multi-layered tab that was previously pre-welded.
The prewelding between the multilayer tabs is completed through ultrasonic welding.
Example 1
In this embodiment, laser is used to weld a multilayer tab and an adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
s1: fixing a plurality of layers of tabs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multilayer aluminum tab, the thickness of a single-layer aluminum tab is 12 micrometers, and the thickness of a single-layer copper tab is 8 micrometers.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 200 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling directions of the copper lug and the aluminum lug are both bow-shaped filling, and the filling intervals are both 0.05 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, a protective gas is supplied to the welding area, whereby the welding area can be prevented from being oxidized during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The flow rate of the protective gas was about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in figure 2.
In fig. 2, the area a is an adapter sheet, the area B is an unwelded multi-layer tab, the area C is a pre-welded multi-layer tab area, the area D is a laser welding print, the area E is a pre-welded multi-layer tab area, and the area F is an unwelded multi-layer tab. As can be seen from FIG. 2, the laser welding has good appearance, uniformity and better welding quality.
Example 2
In this embodiment, laser is used to weld a multilayer tab and an adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
S1: fixing a plurality of layers of pole lugs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multilayer aluminum tab, the thickness of a single-layer aluminum tab is 12 micrometers, and the thickness of a single-layer copper tab is 8 micrometers.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 250 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling directions of the copper lug and the aluminum lug are both bow-shaped filling.
The filling intervals are all 0.06 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, a protective gas is supplied to the welding area, whereby the welding area can be prevented from being oxidized during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The flow rate of the protective gas was about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in figure 3.
In fig. 3, the area D is laser welding mark, and as can be seen from fig. 3, the laser welding mark has good appearance, uniformity and better welding quality.
Example 3
In this embodiment, laser is used to weld a multilayer tab and an adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
s1: fixing a plurality of layers of tabs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multilayer aluminum tab, the thickness of a single-layer aluminum tab is 12 micrometers, and the thickness of a single-layer copper tab is 8 micrometers.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 250 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling directions of the copper lug and the aluminum lug are both bow-shaped filling.
The filling intervals are all 0.08 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, a protective gas is supplied to the welding area, whereby the welding area can be prevented from being oxidized during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The flow rate of the protective gas was about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in figure 4.
In fig. 4, the area D is laser welding mark, and as can be seen from fig. 4, the laser welding mark has good appearance, uniformity and better welding quality.
Example 4
In this embodiment, laser is used to weld a multilayer tab and an adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
s1: fixing a plurality of layers of pole lugs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multilayer aluminum tab, the thickness of a single-layer aluminum tab is 12 micrometers, and the thickness of a single-layer copper tab is 8 micrometers.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 250 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling trend of the copper lug and the aluminum lug is bow-shaped filling.
The filling intervals are all 0.1 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, a protective gas is supplied to the welding area, whereby the welding area can be prevented from being oxidized during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The flow rate of the protective gas was about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in fig. 5.
In fig. 5, the area D is laser welding mark, and as can be seen from fig. 5, the laser welding mark has good appearance, uniformity and better welding quality.
Example 5
In this embodiment, laser is used to weld a multilayer tab and an adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
s1: fixing a plurality of layers of tabs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multilayer aluminum tab, the thickness of a single-layer aluminum tab is 12 micrometers, and the thickness of a single-layer copper tab is 8 micrometers.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 300 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling directions of the copper lug and the aluminum lug are both bow-shaped filling.
The filling intervals are all 0.05 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, a protective gas is supplied to the welding area, whereby the welding area can be prevented from being oxidized during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The flow rate of the protective gas was about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in fig. 6.
In fig. 6, the area D is laser welding mark, and as can be seen from fig. 6, the laser welding mark has good appearance, uniformity and better welding quality.
Example 6
In this embodiment, laser is used to weld a multilayer tab and an adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
s1: fixing a plurality of layers of tabs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multi-layer aluminum electrode lug, the thickness of a single-layer aluminum electrode lug is 12 mu m, and the thickness of a single-layer copper electrode lug is 8 mu m.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 350 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling directions of the copper lug and the aluminum lug are both bow-shaped filling.
The filling intervals are all 0.05 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, a protective gas is supplied to the welding area, whereby the welding area can be prevented from being oxidized during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The flow rate of the protective gas was about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in fig. 7.
In fig. 7, the area D is laser welding mark, and as can be seen from fig. 6, the laser welding mark has good appearance, uniformity and better welding quality.
Example 7
In this embodiment, laser is used to weld a multilayer tab and an adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
s1: fixing a plurality of layers of tabs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multilayer aluminum tab, the thickness of a single-layer aluminum tab is 12 micrometers, and the thickness of a single-layer copper tab is 8 micrometers.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 500 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling trend of the copper tab and the aluminum tab is bow-shaped filling, and the filling distance is 0.05 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, protective gas is supplied to the welding area, thereby preventing oxidation of the welding area during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The flow rate of the protective gas was about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in fig. 8.
In fig. 8, the area D is laser welding mark, and as can be seen from fig. 8, the laser welding mark has good appearance, uniformity and better welding quality.
Example 8
In this embodiment, laser is used to weld a multilayer tab and an adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
s1: fixing a plurality of layers of tabs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multilayer aluminum tab, the thickness of a single-layer aluminum tab is 12 micrometers, and the thickness of a single-layer copper tab is 8 micrometers.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 250 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling directions of the copper lug and the aluminum lug are Z-shaped, and the filling intervals are 0.05 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, a protective gas is supplied to the welding area, whereby the welding area can be prevented from being oxidized during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The flow rate of the protective gas was about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in figure 9.
In fig. 9, the area D is laser welding mark, and as can be seen from fig. 9, the laser welding mark has good appearance, uniformity and better welding quality.
COMPARATIVE EXAMPLE 1 (one-way pack)
The comparative example adopts laser to weld the multilayer tab and the adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
s1: fixing a plurality of layers of tabs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multilayer aluminum tab, the thickness of a single-layer aluminum tab is 12 micrometers, and the thickness of a single-layer copper tab is 8 micrometers.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 250 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling directions of the copper lug and the aluminum lug are all unidirectional filling, and the filling intervals are all 0.05 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, a protective gas is supplied to the welding area, whereby the welding area can be prevented from being oxidized during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The flow rate of the protective gas was about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in fig. 10.
In fig. 10, the region D is laser-welded, and as can be seen from fig. 10, the uniformity of the laser-welded pattern was significantly reduced as compared with example 1, the appearance was not smooth, and the explosion point was observed.
Comparative example 2 (filling intervals are all 0.15mm)
The comparative example adopts laser to weld the multilayer tab and the adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
s1: fixing a plurality of layers of tabs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multilayer aluminum tab, the thickness of a single-layer aluminum tab is 12 micrometers, and the thickness of a single-layer copper tab is 8 micrometers.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 250 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling directions of the copper lug and the aluminum lug are all bow-shaped filling, and the filling intervals are all 0.15 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, protective gas is supplied to the welding area, thereby preventing oxidation of the welding area during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The gas flow rate of the protective gas is about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in fig. 11.
In fig. 11, the region D is laser-welded, and as can be seen from fig. 11, the uniformity of the laser-welded pattern was significantly reduced as compared with example 1, the appearance was not smooth, and the explosion point was observed.
Comparative example 3 (filling intervals are all 0.2mm)
The comparative example adopts laser to weld the multilayer tab and the adapter plate, wherein the number of layers of the prewelded multilayer tab is 50, and the specific steps are as follows:
s1: fixing a plurality of layers of tabs and adapter plates, and determining a welding area;
s2: welding the welding area by laser;
in the multilayer aluminum tab, the thickness of a single-layer aluminum tab is 12 micrometers, and the thickness of a single-layer copper tab is 8 micrometers.
The welding area is rectangular and 2mm × 25mm in size.
The welding adopts a vibrating mirror filling mode.
The transmission mode of the laser is a continuous mode.
The welding speed was 250 mm/s.
The welding power was 300W.
The defocusing amount is 0 mm.
The filling directions of the copper lug and the aluminum lug are all bow-shaped filling, and the filling intervals are all 0.2 mm.
During welding, the laser power is gradually increased from 0 to 100%, and then gradually decreased until welding is completed.
During welding, a protective gas is supplied to the welding area, whereby the welding area can be prevented from being oxidized during welding. The protective gas is delivered by annular side blowing. The protective gas is nitrogen. The flow rate of the protective gas was about 15L/min.
After welding, the appearance of the weld was observed by a VHX-6000 digital microscope system at 20 times magnification.
The appearance of the weld is shown in fig. 12.
In fig. 12, the region D is laser-welded, and as can be seen from fig. 12, the uniformity of the laser-welded pattern was significantly reduced as compared with example 1, the appearance was not smooth, and the explosion point was observed.
The welding parameters of examples 1 to 8, and comparative examples 1 to 3 are summarized in table 1.
TABLE 1 summary of welding parameters for examples and comparative examples
Numbering Speed of welding Welding power Direction of filling Filling the space
Example 1 200mm/s 300W In the bow-shaped trend 0.05mm
Example 2 250mm/s 300W In the bow-shaped trend 0.06mm
Example 3 250mm/s 300W In the bow-shaped trend 0.08mm
Example 4 250mm/s 300W In the bow-shaped trend 0.1mm
Example 5 300mm/s 300W In the bow-shaped trend 0.05mm
Example 6 350mm/s 300W In the bow-shaped trend 0.05mm
Example 7 500mm/s 300W In the bow-shaped trend 0.05mm
Example 8 250mm/s 300W In the Z-shaped direction 0.05mm
Comparative example 1 250mm/s 300W One-way filling 0.05mm
Comparative example 2 250mm/s 300W In the bow-shaped trend 0.15mm
Comparative example 3 250mm/s 300W In the bow-shaped trend 0.2mm
A summary of the weld appearances observed in examples 1 to 8, and comparative examples 1 to 3 is shown in table 2.
For the welding seam, if the appearance is smooth and has no explosion point, the welding seam quality is qualified, otherwise, the welding seam quality is unqualified.
In addition, whether the fracture of the joint position of the molten pool and the lug is qualified or not is observed. Specifically, the metallographic phase is cut perpendicularly to the weld joint, the magnification is 200 times under a metallographic microscope, and whether the joint position of the molten pool and the tab is broken or not is observed. Based on the consideration of overcurrent, if the number of the breaking layers of the single-side lug accounts for less than or equal to 20 percent of the total number of layers, the single-side lug is qualified.
TABLE 2 weld appearance and fracture summary of examples and comparative examples
Figure BDA0003591405160000211
Figure BDA0003591405160000221
It can be observed from fig. 2 to 12 that the weld appearances of examples 1 to 8 all meet the requirements, while the appearances of comparative examples 1 to 3 do not meet the requirements, and the explosion point exists.
In addition, through a metallographic microscope, the positions of the molten pool and the lug connecting position of the examples 1 to 8 are also observed to be qualified, and the positions of the comparative examples 1 to 3 are not qualified.
Specifically, fig. 13 is a metallographic image at 50 times magnification of the welded multilayer tab and adaptor sheet of example 1, wherein the dashed-line frame position is the weld pool and tab junction position, and fig. 14 is a partial 150 times magnification of the weld pool and tab junction position in fig. 13, and it can be seen from fig. 14 that there is no fracture between the weld pool position and tab junction position.
Fig. 15 is a metallographic image showing a 50-fold enlargement of a multilayer tab and an adaptor sheet of comparative example 1 after welding, wherein a dashed-line frame position is a molten pool and tab junction position, and fig. 16 is a partial 150-fold enlargement of the molten pool and tab junction position of fig. 15, and it can be seen from fig. 16 that the molten pool position and tab junction position are seriously broken and fail.
The present invention has been described in detail with reference to the embodiments, but the present invention is not limited to the embodiments described above, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.

Claims (10)

1. A welding method of a multilayer tab is characterized by comprising the following steps:
s1: fixing a plurality of layers of pole lugs and adapter plates, and determining a welding area;
s2: welding the welding area by adopting laser;
the transmission mode of the laser is a continuous mode;
The number of layers of the multilayer tab is more than 20.
2. The welding method of claim 1, wherein the multi-layer tab comprises an aluminum tab and a copper tab.
3. The welding method according to claim 1, wherein the single-layer tab of the multi-layer tab has a thickness of 6 to 12 μm.
4. A welding method according to any one of claims 1 to 3, characterized in that the welding zone is rectangular in shape and has a size of (1mm to 3mm) x (20mm to 30 mm).
5. The welding method according to any one of claims 1 to 3, wherein in step S2, the welding speed is 200mm/S to 500 mm/S.
6. The welding method according to any one of claims 1 to 3, wherein in step S2, the filling mode is galvanometer filling when welding.
7. A welding method according to claim 6, wherein the beam path of the galvanometer-filled laser light is arcuate or Z-shaped.
8. The welding method according to claim 6, wherein the filling pitch of the galvanometer filling is 0.05mm to 0.1 mm.
9. Welding method according to any one of claims 1 to 3, characterized in that the power of the laser is 300W to 3000W.
10. The welding method according to any one of claims 1 to 3, wherein the defocusing amount of the laser is-1.5 to 1.5 mm.
CN202210377662.5A 2022-04-12 2022-04-12 Welding method of multilayer tab Pending CN114833443A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020251134A1 (en) * 2019-06-10 2020-12-17 주식회사 엘지화학 Cylindrical secondary battery having multilayer-structured battery case, and method for manufacturing same
CN113385814A (en) * 2021-06-21 2021-09-14 远景动力技术(江苏)有限公司 Laser welding method and device for multilayer tabs and lithium battery
CN113458635A (en) * 2020-03-31 2021-10-01 比亚迪股份有限公司 Method for welding tab and cover plate and battery assembly
CN113714636A (en) * 2021-08-31 2021-11-30 广东利元亨智能装备股份有限公司 Laser welding method for multilayer tabs
CN113857666A (en) * 2021-09-28 2021-12-31 远景动力技术(江苏)有限公司 Laser welding method and laser welding device for double-layer aluminum lug and double-layer copper lug and lithium battery

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020251134A1 (en) * 2019-06-10 2020-12-17 주식회사 엘지화학 Cylindrical secondary battery having multilayer-structured battery case, and method for manufacturing same
CN113458635A (en) * 2020-03-31 2021-10-01 比亚迪股份有限公司 Method for welding tab and cover plate and battery assembly
CN113385814A (en) * 2021-06-21 2021-09-14 远景动力技术(江苏)有限公司 Laser welding method and device for multilayer tabs and lithium battery
CN113714636A (en) * 2021-08-31 2021-11-30 广东利元亨智能装备股份有限公司 Laser welding method for multilayer tabs
CN113857666A (en) * 2021-09-28 2021-12-31 远景动力技术(江苏)有限公司 Laser welding method and laser welding device for double-layer aluminum lug and double-layer copper lug and lithium battery

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