CN116275521A - A kind of welding method of battery surge plate - Google Patents

Abstract

The invention discloses a welding method of a battery torrent disk, which comprises the steps of exposing positive and negative electrode lugs of a battery core to compact positive and negative electrode end surfaces; the attaching tool is used for respectively and tightly attaching the current collecting disc with the end face of the positive electrode and the end face of the negative electrode; the current collecting discs are provided with welding grooves, and the visual identification device identifies the welding grooves; the galvanometer device is matched with a laser to project laser on the welding surface; adjusting the defocusing amount of the vibrating mirror device, and setting the defocusing amount when welding the collecting disc; setting proper laser parameters; the vibrating mirror devices are respectively arranged on welding tracks in the welding grooves of the collecting disc; the outflow port of the protective gas flow channel of the bonding tool is opposite to the welding surface of the positive electrode and the welding surface of the negative electrode, and inert protective gas is introduced into the protective gas flow channel; the laser emits light, and welding lines with different shapes are formed in the welding grooves of the current collecting disc according to the welding track in a continuous welding mode, so that the current collecting disc is firmly welded on the surface of the tab. The welding strength can be improved by the welding method of the battery torrent disk.

Description

A welding method for a battery surge disc

technical field

The invention relates to the field of battery technology, in particular to a welding method for a surge plate of a battery.

Background technique

Lithium-ion batteries have the advantages of high energy density, safety and pollution-free, long life, and no memory effect. They have been widely used in power vehicles, energy storage, and 3C portable electronic products. In the field of power batteries, cylindrical lithium batteries are a relatively common type of lithium batteries and have received widespread attention.

Laser welding plays a very important role in the production process of electric cores. Because of its advantages such as high welding strength, high energy, fast speed, large depth, and small deformation, laser welding is used in many process links. In the current collector plate welding process of cylindrical batteries, it is necessary to use laser welding to weld the tabs and cover plates together. Since the tabs of cylindrical batteries are all tabs, the welding difficulty is greatly increased, and the laser power is too high. Burn through the diaphragm and copper foil, causing a short circuit in the cell.

The prior art, patent publication number CN114976494A invention patent, a current collecting plate for cylindrical batteries, the current collecting plate includes the upper assembly of the current collecting plate, the lower assembly of the current collecting plate and the connecting column, the upper assembly of the current collecting plate and the collecting plate The lower assembly of the collector tray is rotatably connected through a connecting column; both the upper assembly of the collector tray and the lower assembly of the collector tray include a disk body and several blades, and there are gaps between adjacent blades. When assembling the collector plate, after cutting the lug size according to the structure of the collector plate, the tabs extend to between the upper assembly of the collector plate and the lower assembly of the collector plate, fix the lower assembly of the collector plate, and rotate the upper assembly of the collector plate During the process, the tabs are driven to turn over, and the tabs are pressed tightly by the pressure between the upper assembly of the collector plate and the lower assembly of the collector plate, and welding is performed after the assembly of the collector plate is completed. However, the prior art uses spot welding for welding, and its welding strength is low.

Contents of the invention

The technical problem to be solved by the present invention is to solve the problem of low welding strength due to spot welding of the current collecting discs of all tabs.

In order to solve the above technical problems, the present invention provides the following technical solutions:

A welding method for a battery surge disc, comprising the following steps:

S100, after flattening the positive and negative pole ears of the battery cell, the dense positive and negative pole surfaces are exposed;

S200, the fitting tooling will closely fit the positive current collecting plate and the positive end surface, and closely fit the negative current collecting plate and the negative end surface;

S300, the positive collector plate and the negative collector plate are both provided with welding grooves, and the visual recognition device recognizes the welding grooves;

S400, the vibrating mirror device is matched with a laser, and the laser is projected on the positive electrode welding surface of the positive collector plate and the positive electrode surface and the negative electrode welding surface of the negative collector plate and the negative electrode surface;

S500, adjusting the defocus amount of the galvanometer device, respectively setting the defocus amount of the positive electrode when welding the positive electrode welding surface, and the negative electrode defocus amount when welding the negative electrode welding surface;

S600, setting laser parameters suitable for the positive end surface and the negative end surface;

S700, setting welding tracks in the welding grooves of the positive current collecting plate and the negative current collecting plate on the vibrating mirror device;

S800, directing the outflow port of the protective air flow channel of the fitting tool to the positive electrode welding surface and the negative electrode welding surface, and introducing an inert protective gas into the protective air flow channel;

S900, the laser emits light, heats the current collecting plate, melts the tabs on the positive and negative electrode surfaces that are close to it, and uses continuous welding according to the welding track in the welding groove of the current collecting plate Welding patterns of different shapes are formed, so that the current collecting plate is firmly welded on the surface of the lug.

Advantages: The collector plate is welded on the surface of the lug by continuous welding, the processing speed is fast, the welding rate is greatly improved, and the burning through of the foil and the diaphragm is avoided while the welding strength is increased, and the short circuit rate is reduced. Soldering rate, so the manufacturing rate of batteries is greatly improved, material waste is reduced, and costs are reduced.

In an embodiment of the present invention, the material of the positive current collector is aluminum, and the surface of the positive current collector is roughened by physical sandblasting; and the welding power density of the positive current collector 6300w/mm ² to 8100w/mm ² .

In an embodiment of the present invention, the material of the negative current collector is copper, and the surface of the negative current collector is plated with nickel; and the welding power density of the negative current collector is 15800w/mm ² ~22700w/mm ² .

In an embodiment of the present invention, the fiber core diameter of the laser is 100-200um, and the spot diameter at the focus is 200-600um.

In an embodiment of the present invention, the defocusing amount of the positive electrode is +24 mm to +28 mm, and the defocusing amount of the negative electrode is +4 mm to +20 mm.

In an embodiment of the present invention, the laser parameters suitable for the positive end surface and the negative end surface include: the focal length of the galvanometer diameter of the galvanometer device is 80-140 mm, and the focal length of the galvanometer focusing lens is 200-400 mm The working range field of the galvanometer device is 110mm * 110mm or 220mm * 220mm; the working focus distance of the galvanometer device is 200 ~ 300mm; The multiple is 2 to 3 times.

In an embodiment of the present invention, when the laser is welding the positive welding surface, its welding power is 1800w-2300w, and the welding speed is 20-100mm/s; when the laser is welding the negative welding surface, its The welding power is 2600w~3200w; the welding speed is 40~120mm/s.

In an embodiment of the present invention, when welding the positive electrode welding surface, welding is not oscillating along the welding track straight line; when welding the negative electrode welding surface, oscillating welding is performed along the welding track in the form of a sinusoidal curve, and the laser Oscillating parameters: the amplitude is 0.6mm~0.8mm, and the frequency is 40~60Hz.

In an embodiment of the present invention, the diameter of the laser spot projected by the laser in the welding groove of the positive current collector is 0.6 mm to 0.7 mm, and the diameter of the laser spot projected by the laser in the welding groove of the negative current collector The laser spot diameter is 0.4mm-0.5mm.

In an embodiment of the present invention, the pressure of the inert protective gas needs to be ≥0.5 MPa, and the flow rate of the inert protective gas is 15L/min˜20L/min.

Compared with prior art, the beneficial effect of the present invention is:

1. The present invention uses laser continuous welding to weld the current collecting plate on the surface of the lug, and the processing speed is fast. It only takes 0.12s to complete a current collecting plate welding, which is 5 times faster than the traditional YAG laser welding speed. With automatic production line, Can achieve 80PPM production efficiency.

2. Compared with the traditional spot welding method, the welding method of the present invention doubles the adhesion area and 1.45 times the overcurrent capacity, effectively improving the internal overcurrent capacity of the battery cell, and is more suitable for charging and discharging with high current or super high current.

3. The welding strength of the welding method of the present invention is 50% higher than that of the traditional spot welding method, which effectively avoids the risk of the collector plate falling off during the automatic production line transportation or the next process.

4. The present invention controls the defocusing amount, distinguishes the laser process parameters of the positive and negative extreme surfaces and the current collecting plate, and finely controls the power density to avoid the heat generated by welding from burning the internal diaphragm of the winding core, and effectively control the micro-short circuit of the battery core.

5. The invention is the first to introduce an inert gas to protect the welding position during the welding process, and the plasma shielding generated by welding will be dispersed by the shielding gas, so as to ensure the continuous and stable welding seam of the laser ability, and greatly reduce the incidence of false welding.

6. The production and maintenance method of the present invention is simple, which can reduce the frequency of maintenance. The welding production process does not need to frequently replace the protective lens, while reducing costs and avoiding downtime for maintenance, resulting in a decrease in line body efficiency. Fiber lasers are selected, which are compact in deconstruction and maintenance-free. And it can effectively reduce the occurrence rate of high reflection, protect the galvanometer and laser

Description of drawings

FIG. 1 is a flow chart of a welding method for a battery surge disk according to the present invention.

Fig. 2 is an effect diagram after welding of the positive current collector of the present invention.

Fig. 3 is an effect diagram after welding of the negative collector plate of the present invention is completed.

Detailed ways

In order to facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention will be further described in conjunction with the accompanying drawings.

The terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present application, "plurality" means two or more, unless otherwise specifically defined.

Please refer to Fig. 1, the present invention provides a welding method for a battery torsion disk, comprising the following steps:

S100, after flattening the positive and negative terminals of the battery, the dense positive and negative terminals are exposed.

Among them, after the positive and negative pole ears of the battery cell are flattened by ultrasonic and mechanical, the dense positive and negative terminal surfaces are exposed. In this embodiment, the tabs are full tabs.

S200, the fitting tool fits the positive current collecting plate and the positive terminal surface tightly, and closely fits the negative current collecting plate and the negative terminal surface.

Wherein, the material of the positive collector plate is aluminum, the material of the negative collector plate is copper, and the materials of the tabs on the positive and negative end faces of the battery are different, and different welding laser parameters need to be used. Meet the welding processing effect and strength requirements. In this embodiment, through experiments and calculations, the welding power density of the positive current collector is 6300w/mm ² -8100w/mm ² , and the welding power density of the negative current collector is 15800w/mm ² -22700w/mm ^2. This can not only ensure the welding strength and adhesion area, but also prevent laser welding from burning the core diaphragm inside the lug.

In the welding process, due to the laser welding method, the copper and aluminum materials have a high reflection of the laser, which not only affects the welding effect, but also the laser reflected back to the optical path will affect the normal operation of the internal components of the galvanometer device and cause high reflection of the laser. Therefore, it is necessary to perform nickel-plating treatment on the surface of the negative collector plate, and use a physical sandblasting process to roughen the surface of the positive collector plate to prevent laser high reflection.

S300, welding grooves are arranged on the positive collector plate and the negative collector plate, and the visual recognition device identifies the weld grooves.

Among them, the laser track is located in the welding groove. The visual recognition device adopts a CCD camera to take pictures, and the recognition algorithm automatically recognizes.

S400, the galvanometer device is matched with a laser, and project the laser on the positive electrode welding surface of the positive collector plate and the positive electrode surface and the negative electrode welding surface of the negative collector plate and the negative electrode surface.

Wherein, in an embodiment of the invention, the galvanometer device adopts an IPG brand 2D high-power galvanometer. The fiber core diameter of the laser is 100-200um, and the spot diameter at the focal point is 200-600um. Specifically, the laser uses YSL-4000-U or YSL-4000-AMB.

In order to further improve the laser high reflection phenomenon and improve the welding quality, the laser can be replaced by a continuous multimode fiber laser with "ring spot" as the light emitting mode or a green light continuous laser with a laser wavelength of 600nm~700nm, and a dedicated green light The galvanometer device is used for welding to effectively improve the laser absorption rate.

S500. Adjust the defocus amount of the vibrating mirror device, respectively setting the defocus amount of the positive electrode when welding the welding surface of the positive electrode and the defocus amount of the negative electrode when welding the welding surface of the negative electrode.

Wherein, the defocusing amount of the positive electrode is +24 mm to +28 mm, and the defocusing amount of the negative electrode is +4 mm to +20 mm. When welding the positive electrode welding surface and the negative electrode welding surface, if the galvanometer device and the laser with the same optical configuration are used, different defocus amounts need to be set.

S600, setting laser parameters suitable for the positive end surface and the negative end surface.

Wherein, in an embodiment of the present invention, the laser parameters suitable for the positive terminal surface and the negative terminal surface include: the focal length of the galvanometer mirror diameter of the galvanometer device is 80-140 mm, and the focal length of the galvanometer focusing mirror is 200~400mm. The working range field of the galvanometer device is 110mm×110mm or 220mm×220mm. The working focus distance of the vibrating mirror device is 200-300 mm. And at the focal point, the magnification of the laser light of the laser by the vibrating mirror device is 2-3 times. When the laser is welding the positive welding surface, the welding power is 1800w-2300w, and the welding speed is 20-100mm/s. When the laser is welding the welding surface of the negative electrode, the welding power is 2600w-3200w, and the welding speed is 40-120mm/s.

S700, setting welding traces in the welding grooves of the positive current collecting plate and the negative current collecting plate on the vibrating mirror device.

On the optical path editing software of the galvanometer device, set the welding trajectory paths of the positive current collector and the negative current collector. Wherein, when welding the welding surface of the positive electrode, due to the low power density required by the aluminum material, the diameter of the laser spot projected by the laser in the welding groove of the positive current collecting plate is relatively large, and the diameter of the laser spot is 0.6 mm to 0.7 mm. mm. Laser linear welding can achieve the required adhesion area, and can also avoid heat accumulation and burn the core diaphragm inside the lug. Therefore, when welding the positive collector plate, it is welded in a straight line along the welding track without swinging.

When welding the welding surface of the negative electrode, due to the high power density required by the copper material, the diameter of the laser spot projected by the laser in the welding groove of the negative current collector is relatively small, and the diameter of the laser spot is 0.4 mm to 0.5 mm. Straight line welding cannot reach the required adhesion area, so laser oscillation swing welding is used to meet the adhesion area. When welding, it swings and welds along the welding track in the form of a sinusoidal curve. The type of laser oscillation swing curve: sinusoidal curve, swing amplitude : 0.6mm ~ 0.8mm, swing frequency: 40 ~ 60Hz, after testing this parameter, it can avoid burning the core diaphragm inside the lug.

During the welding process, the collector plate is located in the center of the welding area of the galvanometer device, and its relative position to the galvanometer device remains fixed. The two sets of reflective mirrors driven by the motor inside the galvanometer device of the laser rotate to realize the beam movement.

S800. Make the outflow port of the protective gas flow channel of the fitted tooling face the positive electrode welding surface and the negative electrode welding surface, and inject an inert protective gas into the protective air flow channel.

Among them, a large amount of plasma will be generated during the welding process, shielding the laser energy, causing the laser energy density to be lower than the required value, resulting in virtual welding. Therefore, an inert protective gas must be introduced at the welding position during the whole welding process to remove the plasma shielding. Among them, the pressure of the inert protective gas needs to be ≥0.5MPa, the flow rate of the inert protective gas is 15L/min～20L/min, and the type of inert protective gas should be selected from one or more of the inert gases, among which helium It is the best, because helium can effectively protect the welding position, form a stable atmosphere, do not participate in the reaction with the welding metal, and because it is not easy to be ionized, it can effectively dissipate the plasma. Specifically, the inert protective gas includes but is not limited to a mixture of one or more of N2, He, Ne, Ar, Kr, Xe, and Rn.

S900, the laser emits light, heats the current collecting plate, melts the tabs on the positive and negative electrode surfaces that are close to it, and uses continuous welding according to the welding track in the welding groove of the current collecting plate Welding patterns of different shapes are formed, so that the current collecting plate is firmly welded on the surface of the lug.

Please refer to Fig. 1 to Fig. 3, in an embodiment of the present invention, after the welding is completed, the welding strength tensile test and the welding completion cell short-circuit test are carried out with the wire body. The specific implementation method is: after the welding is completed, the mechanical The claws automatically clamp the position where the collector plate is connected to the top cover of the cell, and apply a pulling force of 150N to the collector plate and the winding core. If the collector plate does not fall off, it is judged to be qualified, and if the collector plate falls off, it is judged to be unqualified. After the welding strength tensile test is completed, the precision short-circuit tester is connected to the welded collector plate and the battery core. If no short-circuit current is detected, it is judged as qualified, otherwise it is unqualified.

Comparative example verification

Please refer to Fig. 1, in one embodiment of the present invention, the visual recognition device adopts a CCD camera to take pictures, and the vibrating mirror device adopts an IPG brand 2D high-power vibrating mirror, which is matched with YSL-4000-AMB multi-mode continuous annular spot optical fiber Laser, after the laser is focused by the vibrating mirror device, the spot diameter of the focus position is 375um, the defocusing amount of the positive electrode is 26mm, and the defocusing amount of the negative electrode is 4mm. At this time, the distance of the defocusing amount of the positive electrode has exceeded the laser beam Rayleigh length, and the defocusing amount of the negative electrode does not exceed the Rayleigh length of the laser beam, so the penetration of the negative current collector plate has a strong thermal conductivity, and the positive current collector plate will not shrink the internal diaphragm due to excessive laser energy, resulting in battery short circuit. The galvanometer diameter focal length of the galvanometer device is 140mm, and the focal length of the galvanometer focusing lens is 400mm. When the laser is welding the positive electrode welding surface, the welding power is 1800w, the welding speed is 60mm/s, and the swinging function of the laser is turned off. When the laser is welding the negative welding surface, the welding power is 2800w, the welding speed is 80mm/s, the swing function of the laser is turned on, the swing amplitude is 0.6mm, the swing frequency is 45Hz, and the flow rate of the inert shielding gas is 15L/min. After the welding is completed, it takes 1.2s to complete the welding of each collector plate, and the average value of the test connection strength is about 100N.

The comparative example is consistent with the step S100 to step S300 of the present invention, and then use the YAG laser to collimate the welding head, and realize the only displacement of the welding head through the three-axis servo motor and the slide rail, and spot welding at the preset welding point , the motor starts again, drives the welding head to the next point, and welds again until all spot welding is completed. The motor does not move during the spot welding process to ensure the welding effect. Among them, the displacement speed of the motor in the comparative example is 80mm/s. At this time, the power of the laser light is: 1200w, and the single-point welding time is: 50ms. There is no need to blow protective gas to protect the welding surface. It takes time to complete spot welding of a current collector. 2min, the average test connection strength is 50N.

Compared with the comparative example in this application, the adhesion area of the current collecting plate is increased by 50%, and the connection strength of the current collecting plate after welding is increased by 100%. The time consumption is 1% of the comparative example, and the efficiency is increased by 100 times. The internal resistance value is 30% lower than that of the comparative example. The average short-circuit pass rate of the battery collector plate after welding for the long-term production measurement application is 99.47%, and the average short-circuit pass rate of the battery collector plate of the comparative example is 98.87%, and the pass rate is increased by 0.6%. .

It will be apparent to those skilled in the art that the invention is not limited to the details of the above-described exemplary embodiments, but that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Accordingly, the embodiments should be regarded in all points of view as exemplary and not restrictive, the scope of the invention being defined by the appended claims rather than the foregoing description, and it is therefore intended that the scope of the invention be defined by the appended claims rather than by the foregoing description. All changes within the meaning and range of equivalents of the elements are embraced in the invention, and any reference sign in a claim shall not be construed as limiting the claim concerned.

The above-described embodiments only represent the implementation of the invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments. For those skilled in the art, some deformations and changes can also be made without departing from the concept of the present invention. Improvements, these all belong to the protection scope of the present invention.

Claims (10)

1. A welding method for a battery torrent disk, comprising the following steps: S100, after flattening the positive and negative pole ears of the battery cell, the dense positive and negative pole surfaces are exposed; S200, the fitting tooling will closely fit the positive current collecting plate and the positive end surface, and closely fit the negative current collecting plate and the negative end surface; S300, the positive collector plate and the negative collector plate are both provided with welding grooves, and the visual recognition device recognizes the welding grooves; S400, the vibrating mirror device is matched with a laser, and the laser is projected on the positive electrode welding surface of the positive collector plate and the positive electrode surface and the negative electrode welding surface of the negative collector plate and the negative electrode surface; S500, adjusting the defocus amount of the galvanometer device, respectively setting the defocus amount of the positive electrode when welding the positive electrode welding surface, and the negative electrode defocus amount when welding the negative electrode welding surface; S600, setting laser parameters suitable for the positive end surface and the negative end surface; S700, setting welding tracks in the welding grooves of the positive current collecting plate and the negative current collecting plate on the vibrating mirror device; S800, directing the outflow port of the protective air flow channel of the fitting tool to the positive electrode welding surface and the negative electrode welding surface, and introducing an inert protective gas into the protective air flow channel; S900, the laser emits light, heats the current collecting plate, melts the tabs on the positive and negative electrode surfaces that are close to it, and uses continuous welding according to the welding track in the welding groove of the current collecting plate Welding patterns of different shapes are formed, so that the current collecting plate is firmly welded on the surface of the lug. 2. The welding method of the battery surge plate according to claim 1, wherein the material of the positive current collecting plate is aluminum, and the surface of the positive current collecting plate is roughened by using a physical sandblasting process ; and the welding power density of the positive current collector is 6300w/mm ² -8100w/mm ² . 3. The welding method of the battery surge plate according to claim 2, wherein the material of the negative current collecting plate is copper, and the surface of the negative current collecting plate is nickel-plated; and the negative current collecting plate is The welding power density of the collector plate is 15800w/mm ² -22700w/mm ² . 4 . The welding method of a torsion disc for a battery according to claim 1 , wherein the fiber core diameter of the laser is 100-200 um, and the spot diameter at the focal point is 200-600 um. 5 . The welding method of a battery surge disk according to claim 1 , wherein the defocusing amount of the positive electrode is +24 mm to +28 mm, and the defocusing amount of the negative electrode is +4 mm to +20 mm. 6 . 6. The welding method of a battery torrent disc according to claim 1, wherein the laser parameters suitable for the positive terminal surface and the negative terminal surface include: the galvanometer diameter focal length of the galvanometer device is 80 ～140mm, the focal length of the galvanometer focusing lens is 200～400mm; the working range field of the galvanometer device is 110mm×110mm or 220mm×220mm; the working focal length of the galvanometer device is 200～300mm; at the focal point, the The magnification of the laser beam by the vibrating mirror device is 2-3 times. 7. The welding method of a battery surge disk according to claim 6, wherein when the laser is welding the positive electrode welding surface, its welding power is 1800w-2300w, and the welding speed is 20-100mm/s; When the laser is welding the welding surface of the negative electrode, the welding power is 2600w-3200w; the welding speed is 40-120mm/s. 8. The welding method of the battery surge disc according to claim 1, characterized in that, when welding the positive electrode welding surface, welding is performed along a straight line of the welding track without swing welding; when welding the negative electrode welding surface, along the welding track to The oscillation welding in the form of a sinusoidal curve, the oscillation parameters of the laser: the amplitude is 0.6mm-0.8mm, and the frequency is 40-60Hz. 9. The welding method of the current collector plate of the battery according to claim 3, characterized in that, the diameter of the laser spot projected by the laser in the welding groove of the positive current collector is 0.6 mm to 0.7 mm, and the diameter of the laser spot projected by the laser is The diameter of the laser spot in the welding groove of the negative current collector is 0.4mm-0.5mm. 10 . The welding method for the surge plate of a battery according to claim 9 , wherein the pressure of the inert shielding gas must be ≥0.5 MPa, and the flow rate of the inert shielding gas is 15L/min˜20L/min. 11 .

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