Lithium battery tab surface treatment device and processing method

Abstract

The present invention discloses a surface treatment device and processing method for a lithium battery tab, including a texturing and dust removal device, the texturing and dust removal device including a texturing and dust removal chamber, a laser texturing head and a side blowing device extending into the texturing and dust removal chamber, and the texturing and dust removal device is provided with an opening and an exhaust port that are connected to the texturing and dust removal chamber. The processing device of this scheme can perform laser texturing on the tab online, and can freely set texturing parameters, such as the diameter, density, number and distribution of texturing points, etc., to improve the surface roughness of the tab, change the surface morphology of the tab, effectively improve the ultrasonic welding qualification rate and reliability, and at the same time increase the area and thickness of the interface diffusion bonding layer, and improve the welding tension of ultrasonic welding.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery production and manufacturing, and in particular to a lithium battery tab surface treatment device and a processing method. Background Art

[0002] Metal ultrasonic welding technology is an emerging solid-state special connection method. It is one of the high-tech technologies based on physics, electronics, mechanical vibration, materials and other disciplines. Its principle is to use the high-frequency vibration of ultrasound, under the action of positive load, to convert the ultrasonic vibration energy into friction work and deformation energy between the welded metal parts, clean the welded metal interface through friction to achieve a clean surface, and then bond and diffuse between the welded metals through limited temperature rise and plastic deformation, thereby forming a reliable solid-phase connection. The quality of ultrasonic welding directly affects the charging and discharging performance of the battery cell and is one of the core key processes in lithium battery manufacturing. Due to the lack of online non-destructive testing methods, this process currently uses sampling-destructive testing methods to monitor the process. As the capacity of single lithium batteries increases, the number of tab layers increases accordingly. Taking 12-micron aluminum foil as an example, it gradually increases from the conventional 20-60 layers to 60-100 layers, and some batteries reach more than 100 layers, which puts higher requirements on the ultrasonic welding process. For ultrasonic welding of more than 60 layers, the pass rate and reliability of ultrasonic welding cannot meet the requirements of mass production. The factors that affect the qualification rate and reliability of ultrasonic welding mainly include the following two aspects: (1) ultrasonic welding machine parameters: welding amplitude, welding pressure, welding frequency, welding time, ultrasonic equipment stability, etc.; (2) substrate properties: surface characteristics (roughness, oxide), physical and chemical properties (material microstructure), welding temperature, etc.

[0003] For example, Chinese patent publication number CN107671414B, publication date September 15, 2020, is entitled "Lithium-ion Battery Tab Ultrasonic Welding Method and Tab Welding Protection Method". A protective sheet is provided on the ultrasonic welding area of ​​the stacked tab foils. When the protective sheet is wrapped on the stacked tab foils, the protective sheet is bent twice from the lower side of the stacked tab foils and then attached to the upper side of the stacked tab foils. The protective sheet is made into a U-shaped structure, and the U-shaped structure is composed of a lower side segment, an upper side segment, and an intermediate segment connected between the upper side segment and the lower side segment, and is elastic. The protective sheet is clamped to the outer periphery of the stacked tab foils by the elastic deformation force, and the welding head of the ultrasonic welding device is pressed on the protective sheet for ultrasonic welding.

[0004] The disadvantage of the existing patent is that as the capacity of a single lithium battery increases, the number of tab layers increases accordingly, which affects the pass rate and reliability of ultrasonic welding at the tabs of the lithium battery. Summary of the invention

[0005] The purpose of the present invention is to solve the problem in the prior art that as the capacity of a single lithium battery increases, the number of tab layers increases accordingly, resulting in reduced pass rate and reliability of ultrasonic welding at the lithium battery tabs. A lithium battery tab surface treatment device and processing method are provided for performing laser roughening treatment on the surface of the lithium battery tab to improve the subsequent tab ultrasonic welding quality.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A lithium battery tab surface treatment device includes a roughening and dust removal device, the roughening and dust removal device includes a roughening and dust removal chamber, a laser roughening head extending into the roughening and dust removal chamber, and a side blowing device, the roughening and dust removal device is provided with an opening and an exhaust port that are connected to the roughening and dust removal chamber. The present invention mainly uses a laser roughening head to perform laser roughening treatment on the tab surface to form a certain array of roughening points, increase the tab surface roughness from the original Ra≤0.1 micron to 0.5-4 microns, and change the tab surface morphology. At the same time, the laser roughening treatment also has a certain cleaning effect on the dirt on the tab surface. According to different materials and products, the diameter, density, number and distribution of the roughening points on the tab surface can be freely adjusted, effectively improving the ultrasonic welding pass rate and reliability, while also increasing the area and thickness of the interface diffusion bonding layer and improving the welding tension of ultrasonic welding. The pole piece runs through the opening of the texturing and dust removal device, the pole ear is located in the texturing and dust removal chamber, and the laser texturing head performs laser texturing on the pole ear. The main function of the side blowing device is to blow air from the side when the laser irradiates the surface of the substrate to form a molten pool, so that a boss is formed at the texturing point on the surface of the pole ear. The air outlet faces the texturing area to adjust the boss height and the texturing morphology of the texturing point.

[0008] Preferably, a supporting device is further included, wherein the supporting device includes a supporting plate with one end extending into the texturing and dust removal chamber, an air suction chamber is provided in the supporting plate, an air suction micro-hole is provided on the upper surface of the supporting plate and is connected to the air suction chamber, and the opening is located above the supporting plate. The supporting plate plays a role in stabilizing the pole piece, so that the pole ear runs smoothly during texturing. If the pole piece runs stably, the laser texturing device may not be equipped with a supporting plate.

[0009] Preferably, the side-blowing device comprises an air inlet branch pipe and an air outlet duct connected to the air inlet branch pipe, and the air outlet on the air outlet duct is arranged obliquely toward the surface of the pole ear.

[0010] Preferably, the cross section of the air outlet of the air outlet duct is flush with the connection between the pole ear and the pole piece, and the width of the air outlet of the air outlet duct is greater than the width of the roughened area on the pole ear.

[0011] Preferably, the laser texturing head is provided with a galvanometer and a chopper disk. The laser texturing head contains a galvanometer, a chopper disk and other devices, which can respond to the process parameter settings and adjust the laser power, frequency, etc. to achieve the effect of obtaining a specific texturing point surface morphology.

[0012] Preferably, the supporting device further comprises a mounting plate and a roller arranged on the mounting plate and driven by a driving device.

[0013] Preferably, the support plate is arranged on the mounting plate, and one end of the support plate fixed on the mounting plate is connected to the vacuum pipe, so that the suction micropores have a certain negative pressure to adsorb the pole piece, and the vacuum flow is adjusted so that the adsorption force on the pole piece is small, which can stabilize the pole piece without affecting the movement of the pole piece.

[0014] Preferably, when the pole ears and pole pieces of the lithium battery are located on the support plate, the pole ears and pole pieces cover the air intake micropores on the support plate to prevent the air intake micropores from directly sucking air from the outside.

[0015] Preferably, the upper surface of the support plate is provided with a Teflon coating to reduce surface friction.

[0016] A method for processing the surface of a lithium battery tab using any one of the above-mentioned devices for processing the surface of the tab, comprising the following steps:

[0017] S1. Arrange the texturing dust removal device, the supporting device and the roller on the mounting plate;

[0018] S2. Setting laser texturing parameters, wherein the laser texturing parameters include: diameter, density, number and distribution of texturing points;

[0019] S3. Set the pole piece running speed. The calculation method is as follows:

[0020]

[0021] If X≥0.8, a pole piece cache device is configured; if X<0.8, no pole piece cache device is required.

[0022] Where: L is the spacing between the roughening points, D is the diameter of the roughening points, a is the ultrasonic welding width, b is the ultrasonic welding length, Hz is the laser frequency, and V is the pole piece running speed;

[0023] S4, placing the pole piece on a roller, the roller drives the pole piece to run, the pole ear on the pole piece passes through the texturing and dust removal chamber through the opening, and the texturing and dust removal device performs laser texturing and dust removal treatment on the surface of the pole ear.

[0024] Therefore, the present invention has the following beneficial effects: the processing device of the present invention can perform laser texturing on the pole ear online, and can freely set texturing parameters, such as the diameter, density, number and distribution form of the texturing points, etc., to improve the surface roughness of the pole ear, change the surface morphology of the pole ear, and effectively improve the ultrasonic welding qualification rate and reliability. At the same time, it will also increase the area and thickness of the interface diffusion bonding layer, and improve the welding tension of ultrasonic welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present invention.

[0026] Figure 2 It is an exploded view of the present invention.

[0027] Figure 3 It is an exploded view of the texturing dust removal device in the present invention.

[0028] Figure 4 It is a structural schematic diagram of the support plate in the present invention.

[0029] Figure 5 It is a microscopic diagram of the roughening point on the lug.

[0030] Figure 6 It is a structural schematic diagram of the pole ear in the present invention.

[0031] As shown in the figure: texturing and dust removal chamber 1, laser texturing head 2, side blowing device 3, air inlet branch pipe 3.1, air outlet duct 3.2, opening 4, air exhaust port 5, support plate 6, air suction microhole 7, mounting plate 8, roller 9, pole ear 10, pole piece 11, texturing point 12, boss 13. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the technical solution embodiments of the present invention clearer, the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0033] Embodiment 1, as Figures 1 to 6A lithium battery tab surface treatment device shown includes a roughening and dust removal device, which includes a roughening and dust removal chamber 1, a laser roughening head 2 and a side blowing device 3 extending into the roughening and dust removal chamber 1, and an opening 4 and an exhaust port 5 that are connected to the roughening and dust removal chamber 1 are provided on the roughening and dust removal device. The present invention mainly uses the laser roughening head 2 to perform laser roughening treatment on the surface of the tab 10 to form a certain array of roughening points, and increases the surface roughness of the tab 10 from the original Ra≤0.1 micron to 0.5-4 microns, thereby changing the surface morphology of the tab 10. At the same time, the laser roughening treatment also has a certain cleaning effect on the dirt on the surface of the tab 10. According to different materials and products, the diameter, density, number and distribution form of the roughening points on the surface of the tab 10 can be freely adjusted, which effectively improves the pass rate and reliability of ultrasonic welding, and at the same time increases the area and thickness of the interface diffusion bonding layer, thereby improving the welding tension of ultrasonic welding. The pole piece 11 runs through the opening 4 of the texturing and dust removal device, the pole ear 10 is located in the texturing and dust removal chamber 1, and the laser texturing head 2 performs laser texturing on the pole ear 10. The side blowing device 3 mainly blows air from the side when the laser is irradiated to the surface of the substrate to form a molten pool, so that a boss 13 is formed at the texturing point on the surface of the pole ear 10, and the air outlet faces the texturing area to adjust the height of the boss 13 at the texturing point and the texturing morphology.

[0034] In the above embodiment, the laser texturing head 2, the texturing dust removal chamber 1 and the side-blowing device are mainly used. The laser texturing head 2 has laser control components such as galvanometers, scenes, isolators, etc., which generate lasers of a certain power according to parameter settings and emit them according to a certain frequency and path. The laser texturing head 2 is sealed and installed on the upper part of the texturing dust removal chamber 1, and is aimed at the texturing area of ​​the pole ear 10 when working. The texturing dust removal chamber 1 is provided with an exhaust port 5, which is mainly used to extract dust and side-blowing gas in the texturing process, forming a certain cavity negative pressure to prevent dust from diffusing to the surface of the pole piece 11. Figure 5 , Figure 6 As shown, the side blowing device 3 includes an air inlet branch pipe 3.1 and an air outlet pipe 3.2, the air outlet is aimed at the texturing area, and the height of the texturing point boss 13 and the texturing morphology are adjusted. The problem in the prior art that as the capacity of the single lithium battery increases, the number of layers of the tab 10 increases accordingly, affecting the pass rate and reliability of ultrasonic welding at the tab 10 of the lithium battery is solved.

[0035] like Figure 1 , Figure 2 , Figure 4 As shown, the laser texturing device further includes a support device, which includes a support plate 6 with one end extending into the texturing dust removal chamber 1, an air suction chamber is provided in the support plate 6, and an air suction micro-hole 7 which is connected to the air suction chamber is provided on the upper end surface of the support plate 6, and the opening is located above the support plate 6. The support plate 6 plays a role in stabilizing the pole piece 11, so that the pole ear 10 runs smoothly during texturing. If the pole piece 11 runs stably, the laser texturing device may not be equipped with the support plate 6.

[0036] like Figure 1 , Figure 2 , Figure 3 As shown, the side blowing device 3 includes an air inlet branch pipe 3.1 and an air outlet pipe 3.2 connected to the air inlet branch pipe 3.1, and the air outlet on the air outlet pipe 3.2 is arranged obliquely toward the surface of the pole lug 10. The cross section of the air outlet of the air outlet pipe 3.2 is flush with the connection between the pole lug 10 and the pole piece 11, and the width of the air outlet of the air outlet pipe 3.2 is greater than the width of the texturized area on the pole lug 10. The air outlet height is ≤5mm, and the air outlet is 5-10mm away from the surface of the pole lug 10.

[0037] The laser texturing head 2 is provided with a galvanometer and a chopper disk. The laser texturing head 2 contains a galvanometer, a chopper disk and other devices, which can respond to the process parameter settings and adjust the laser power, frequency, etc. to achieve the effect of obtaining a specific texturing point surface morphology.

[0038] like Figure 1 , Figure 2 , Figure 4 As shown, the support device also includes a mounting plate 8 and a roller 9 arranged on the mounting plate 8 and driven by a driving device. The ear 10 texturing device can be quickly selected and installed on the existing die-cutting machine, winding machine and stacking machine through the mounting plate 8, without interfering with the original equipment structure. The support plate 6 is arranged on the mounting plate 8, and one end of the support plate 6 fixed on the mounting plate 8 is connected to the vacuum pipe. The suction micropores 7 have a certain negative pressure to adsorb the pole piece 11, and the vacuum flow is adjusted so that the adsorption force on the pole piece 11 is small, which can stabilize the pole piece 11 without affecting the movement of the pole piece 11. When the ear 10 and the pole piece 11 of the lithium battery are located on the support plate 6, the ear 10 and the pole piece 11 cover the suction micropores 7 on the support plate 6. To prevent the suction micropores 7 from directly sucking air from the outside. A Teflon coating is provided on the upper end surface of the support plate 6. To reduce surface friction.

[0039] Embodiment 2, a method for processing the surface of a lithium battery tab using any one of the above-mentioned devices for processing the surface of the tab, comprising the following steps:

[0040] S1, placing the texturing and dust removal device, the supporting device and the roller 9 on the mounting plate 8;

[0041] S2. Setting laser texturing parameters, which include: diameter, density, number and distribution of texturing points;

[0042] S3, configure the buffer device of the pole piece 11 according to the running speed of the pole piece 11, and the calculation method is as follows:

[0043]

[0044] If X≥0.8, the pole piece 11 buffer device is configured; if X<0.8, the pole piece 11 buffer device is not required.

[0045] Wherein: L is the spacing between the roughening points, D is the diameter of the roughening points, a is the ultrasonic welding width, b is the ultrasonic welding length, Hz is the laser frequency, and V is the running speed of the pole piece 11;

[0046] S4, placing the pole piece 11 on the roller 9, the roller 9 drives the pole piece 11 to run, the pole ear 10 on the pole piece 11 passes through the opening 4 and the texturing dust removal chamber 1, and the texturing dust removal device performs laser texturing and dust removal treatment on the surface of the pole ear 10.

[0047] Through experimental tests, we can get:

[0048] Diameter of the roughening point: According to experimental verification, the diameter of the roughening point of the tab 10 is preferably 60-150 microns. At the same time, the optimal diameter of the roughening point is related to the thickness of the tab 10. The thicker the thickness, the larger the required diameter. The diameter of the roughening point of the tab 10 is preferably 10-100 microns.

[0049] Density of roughening points: After experimental verification, the density of 10 roughening points of the tab is 10-60 / mm 2 It is appropriate to obtain better ultrasonic welding quality. The density of roughening points of conventional 12-micron aluminum foil is preferably 15-20 / mm2. For the case where the aluminum foil has high strength or the surface is not clean or the thickness is ≥20 microns, the density of roughening points can be appropriately increased. The density of roughening points of 10 tabs is preferably 5-40 / mm2, which can obtain better ultrasonic welding quality. For the case where the copper foil has high strength or the surface is not clean or the thickness is ≥10 microns, the density of roughening points can be appropriately increased.

[0050] Diameter of roughening point: The diameter of roughening point of tab 10 should be between 30-170 microns. If it is too large, it will easily cause the molten pool to be too deep, and there is a risk of melting through tab 10. For common 12-micron aluminum foil and 6-micron copper foil, the roughening diameter is preferably between 30-90 microns.

[0051] Surface roughness: The surface roughness should be between Ra0.4-5 microns to obtain a better ultrasonic welding window. It can generally be set at Ra0.5-1.5 microns. The specific surface roughness can be optimized experimentally according to the selected material.

[0052] In addition, the laser power should not be too large. Generally, the laser power should be ≤100W. The specific selection needs to be determined after comprehensive experiments based on the texturing parameters.

[0053] Corresponding experimental cases:

[0054] Cell information: installed on the winding machine, 70 layers of cells, 12 micron aluminum foil, 6 micron copper foil, winding speed 1.8 m / min, ultrasonic welding area 5 mm*16 mm;

[0055] Operation data without roughening treatment: the first pass rate is 99.4%, the average offline sampling welding tensile force is 64N, and the average welding residual area is 56%;

[0056] Laser texturing parameters: roughness of aluminum foil Ra0.9 micron, copper foil Ra1.3 micron, texturing point diameter 60 micron, texturing point density 18 / mm2;

[0057] Operation data after roughening treatment: first-time qualified rate is 99.99%, the average value of offline sampling welding tensile force is 75N, and the average value of welding residual area is 80%.

[0058] The specific embodiments described above are only preferred implementations of the present invention, and are not intended to limit the specific implementation scope of the present invention. All equivalent changes made according to the shape and structure of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for processing the surface of a lithium battery tab, characterized in that: The processing device includes: A texturing dust removal device, the texturing dust removal device comprises a texturing dust removal chamber, a laser texturing head and a side blowing device extending into the texturing dust removal chamber, and the texturing dust removal device is provided with an opening and an air exhaust port which are connected to the texturing dust removal chamber; A supporting device, the supporting device comprising a mounting plate, and a roller arranged on the mounting plate and driven by a driving device; Methods include: S1. Arrange the texturing dust removal device, the supporting device and the roller on the mounting plate; S2. Setting laser texturing parameters, which include: diameter, density, number and distribution of texturing points; S3. Set the pole piece running speed. The calculation method is as follows: If X≥0.8, a pole piece buffer device is configured; if X<0.8, no pole piece buffer device is required; Where: L is the spacing between the roughening points, D is the diameter of the roughening points, a is the ultrasonic welding width, b is the ultrasonic welding length, Hz is the laser frequency, and V is the pole piece running speed; S4, placing the pole piece on the roller, the roller drives the pole piece to run, the pole ear on the pole piece passes through the opening and passes through the texturing and dust removal chamber, and the texturing and dust removal device performs laser texturing and dust removal treatment on the surface of the pole ear.

2. A lithium battery tab surface processing method according to claim 1, characterized in that: The support device comprises a support plate with one end extending into the texturing dust removal cavity, an air suction cavity is arranged in the support plate, an air suction micro hole communicating with the air suction cavity is arranged on the upper surface of the support plate, and the opening is located above the support plate.

3. A lithium battery tab surface processing method according to claim 1 or 2, characterized in that: The side-blowing device comprises an air inlet branch pipe and an air outlet duct connected to the air inlet branch pipe, and the air outlet on the air outlet duct is arranged obliquely toward the surface of the pole ear.

4. A lithium battery tab surface processing method according to claim 3, characterized in that: When the laser irradiates the surface of the substrate to form a molten pool, the side blowing device blows air from the side, so that a boss is formed at the roughening point on the surface of the pole ear. The air outlet faces the roughening area to adjust the boss height and the roughening morphology of the roughening point.

5. A lithium battery tab surface processing method according to claim 3, characterized in that: The cross section of the air outlet of the air outlet duct is flush with the connection between the pole ear and the pole piece, and the width of the air outlet of the air outlet duct is greater than the width of the roughened area on the pole ear.

6. A lithium battery tab surface processing method according to claim 1, characterized in that: The laser texturing head is provided with a galvanometer and a chopper disk.

7. A lithium battery tab surface processing method according to claim 2, characterized in that: The support plate is arranged on the mounting plate, and one end of the support plate fixed on the mounting plate is connected to the vacuum pipe.

8. A lithium battery tab surface processing method according to claim 2 or 7, characterized in that: When the pole ears and pole pieces of the lithium battery are located on the support plate, the pole ears and pole pieces cover the air intake micropores on the support plate.

9. A lithium battery tab surface processing method according to claim 8, characterized in that: The upper end surface of the support plate is provided with a Teflon coating.

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