Lithium battery positive tab welding method based on multi-welding-print design and cylindrical lithium battery

Abstract

The invention discloses a lithium battery positive tab welding method based on a multi-welding-print design and a cylindrical lithium battery, and the lithium battery positive tab welding method based on the multi-welding-print design comprises the following steps: in a welding area of a positive tab and a current collector, adopting an arrangement mode of multi-spot welding print or multi-line welding print; the multi-spot printing adopts a grid shape and adopts an annular array; the multi-line welding printing adopts parallel lines; the multi-spot welding printing or the multi-line welding printing adopts a laser welding process or an ultrasonic welding process. Through multi-welding-mark collaborative welding, the welding strength is improved, the pseudo soldering probability is reduced, and the process stability is enhanced; by means of the multi-welding-print design and stress dispersion, the welding strength is improved by 30%-50% compared with that of a traditional single welding print; through the multi-welding-print redundancy design, even if individual welding spots fail, the overall conductivity can still be maintained; and the production debugging cost is reduced by improving the tolerance of equipment parameter fluctuation.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery manufacturing, and in particular relates to a lithium battery positive electrode ear welding method based on a multi-weld print design and a cylindrical lithium battery. Background Art

[0002] In the lithium battery manufacturing process, the positive tab (tab) is a key component that connects the positive electrode material inside the battery with the external circuit. Its welding quality directly affects the battery's conductivity, safety, and cycle life. Traditional welding processes usually use a single-point or single-line welding design, but there are the following problems:

[0003] Insufficient welding strength: Single-point welds are prone to cracking due to stress concentration, especially mechanical fatigue caused by thermal expansion and contraction during battery charging and discharging.

[0004] High risk of cold solder joints: If parameters fluctuate during the soldering process, such as temperature and pressure, a single solder joint may easily cause increased resistance or even complete desoldering due to poor contact.

[0005] Low process tolerance: The equipment requires extremely high precision and frequent calibration, which increases production costs and time.

[0006] Although existing technologies have attempted to improve welding performance by optimizing welding materials or adjusting weld shape, such as circular or rectangular, it is still difficult to completely solve the above-mentioned problems. Therefore, a new welding structure and method that can both improve welding strength and reduce the risk of cold welds is urgently needed.

[0007] In order to solve the above problems, the present invention is proposed. Summary of the Invention

[0008] An object of the present invention is to provide a lithium battery positive electrode ear welding method based on a multi-weld print design.

[0009] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0010] A lithium battery positive electrode ear welding method based on a multi-weld print design includes the following steps: setting at least two weld prints in the welding area between the positive electrode ear and the current collector, and the weld prints are distributed in a regular or irregular array.

[0011] The weld mark is in the shape of a circle, an ellipse or a long strip, and the area of ​​a single weld mark is 0.5-2mm 2 The distance between adjacent weld marks is 0.3-1mm.

[0012] Preferably, a multi-point welding print or a multi-line welding print arrangement is used

[0013] Furthermore, the multi-spot welding prints are in a grid shape and a ring array.

[0014] Furthermore, the multi-line weld marks use parallel lines.

[0015] Preferably, the multi-point welding or multi-line welding adopts a laser welding process or an ultrasonic welding process.

[0016] In one embodiment, a laser welding process is used, including the following steps:

[0017] S1: Material preparation: positive electrode ear and current collector. The positive electrode ear is made of aluminum with a thickness of 0.2 mm. The current collector is made of aluminum foil with a thickness of 0.1 mm.

[0018] S2: Welding print design: 3×3 grid welding print, single welding print diameter 1mm, spacing 0.5mm;

[0019] S3: Through the laser welding process, the welding parameters of laser welding are as follows: laser power: 300W, pulse frequency: 50Hz, welding time: 0.1s per welding point.

[0020] In one embodiment, an ultrasonic welding process is used, including the following steps:

[0021] S1: Material preparation: positive electrode ear and current collector. The positive electrode ear is made of aluminum with a thickness of 0.2 mm. The current collector is made of aluminum foil with a thickness of 0.1 mm.

[0022] S2: Welding print design: parallel double-line welding print, line width 0.8mm, spacing 0.3mm;

[0023] S3: Ultrasonic welding parameters are as follows: amplitude: 40 μm, pressure: 200 N, welding time: 0.5 s.

[0024] In one embodiment, a laser welding process is used, including the following steps:

[0025] S1: Material preparation: positive electrode ear and current collector. The positive electrode ear is made of aluminum with a thickness of 0.2 mm. The current collector is made of aluminum foil with a thickness of 0.1 mm.

[0026] S2: Welding mark design: adopt annular welding mark, the diameter of single welding mark is 1mm, 8 single welding marks are arranged on the inner ring, and the width of the ring is 2 single welding marks;

[0027] S3: Through the laser welding process, the welding parameters of laser welding are as follows: laser power: 300W, pulse frequency: 50Hz, welding time: 0.1s per welding point.

[0028] Another object of the present invention is to provide a cylindrical lithium battery.

[0029] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0030] A cylindrical lithium battery, wherein the positive electrode adopts the lithium battery positive electrode ear welding method based on the multi-weld print design.

[0031] Compared with the prior art, the present invention has the following beneficial technical effects:

[0032] The present invention sets at least two weld marks in the welding area of ​​the positive electrode ear and the current collector, and the weld marks are distributed in a regular or irregular array; adopts laser or ultrasonic welding technology, and improves welding strength, reduces the probability of cold welding and enhances process stability through collaborative welding of multiple weld marks; through the multi-weld mark design, the stress is dispersed, and the welding strength is increased by 30%-50% compared with the traditional single weld mark; the redundant design of multiple weld marks ensures that even if individual weld points fail, the overall conductive performance can still be maintained; and the tolerance to equipment parameter fluctuations is improved, thereby reducing production and debugging costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below with reference to the accompanying drawings.

[0034] Figure 1 This is a schematic diagram of the traditional single-weld printing structure.

[0035] Figure 2 It is a schematic diagram of the parallel line welding structure of the present invention.

[0036] Figure 3 This is an example diagram of the distribution of multiple weld marks in the present invention.

[0037] Figure 4 This is a comparative data table of welding strength tests of the traditional weld print and the multi-weld print structure of the present invention.

[0038] Figure 5 Schematic diagram of comparative data of welding strength test of traditional welding stamp and multi-welding stamp structure of the present invention. DETAILED DESCRIPTION

[0039] Reference Figure 1-Figure 3 As shown, a lithium battery positive electrode ear welding method based on a multi-weld mark design includes the following steps: setting at least two weld marks in the welding area between the positive electrode ear and the current collector, and the weld marks are distributed in a regular or irregular array.

[0040] Adopt the arrangement mode of multi-point welding print or multi-line welding print.

[0041] The weld mark is in the shape of a circle, an ellipse or a long strip, and the area of ​​a single weld mark is 0.5-2mm 2 The distance between adjacent weld marks is 0.3-1mm.

[0042] The current collector is aluminum foil.

[0043] Figure 3 The multi-spot welding print in the first picture adopts a long grid shape. Figure 3The multi-point welding print in the third picture adopts a circular ring array. Figure 3 The multi-spot weld marks in the second picture use long parallel lines.

[0044] The present invention optimizes the number and distribution of weld marks, disperses welding stress, and expands the effective contact area to improve the overall welding strength.

[0045] The multi-point welding print or the multi-line welding print adopts a laser welding process or an ultrasonic welding process.

[0046] Example 1:

[0047] This embodiment adopts laser welding technology.

[0048] Material preparation: positive electrode ear and current collector. The positive electrode ear is made of aluminum with a thickness of 0.2mm. The current collector is made of aluminum foil with a thickness of 0.1mm.

[0049] Welding mark design: 3×3 grid welding mark, single welding mark diameter 1mm, spacing 0.5mm.

[0050] Through the laser welding process, the welding parameters of laser welding are as follows:

[0051] Laser power: 300W

[0052] Pulse frequency: 50Hz

[0053] Welding time: 0.1s per soldering point

[0054] Verify the results of the welded positive electrode ear:

[0055] Tensile testing shows the weld strength is 45N, compared to 30N for conventional single-stamp welds.

[0056] Resistivity is stable at 0.8mΩ·cm 2 , compared with 1.2mΩ·cm in traditional process 2 .

[0057] Example 2:

[0058] This embodiment adopts ultrasonic welding technology.

[0059] Material preparation: positive electrode ear and current collector. The positive electrode ear is made of aluminum with a thickness of 0.2mm, and the current collector is made of aluminum foil with a thickness of 0.1mm.

[0060] Welding mark design: parallel double-line welding mark, line width 0.8mm, spacing 0.3mm.

[0061] Ultrasonic welding process is used, ultrasonic welding parameters:

[0062] Amplitude: 40μm

[0063] Pressure: 200N

[0064] Welding time: 0.5s

[0065] Verify the above welded positive ear results:

[0066] The tensile test shows that the welding strength reaches 46N.

[0067] Resistivity is stable at 0.8mΩ·cm 2 .

[0068] Through observation, it was found that there was no cold soldering phenomenon, no cracks on the weld surface, and no desoldering after 1000 charge and discharge cycle tests.

[0069] Example 3:

[0070] This embodiment adopts laser welding technology.

[0071] Material preparation: positive electrode ear and current collector. The positive electrode ear is made of aluminum with a thickness of 0.2mm. The current collector is made of aluminum foil with a thickness of 0.1mm.

[0072] Welding mark design: adopts annular welding mark, the diameter of single welding mark is 1mm, 8 single welding marks are arranged on the inner ring, the spacing between adjacent welding marks is 1mm, and the width of the ring is 2 single welding marks.

[0073] Through the laser welding process, the welding parameters of laser welding are as follows:

[0074] Laser power: 300W

[0075] Pulse frequency: 50Hz

[0076] Welding time: 0.1s per soldering point

[0077] Verify the results of the welded positive electrode ear:

[0078] The tensile test shows that the welding strength reaches 40N.

[0079] Resistivity is stable at 0.9mΩ·cm 2 .

[0080] Reference Figure 4 and Figure 5 It can be seen that compared with the traditional single welding print welding strength of 30N and resistivity of 1.2mΩ·cm 2 , the welding strength of the point welding print, parallel line welding print and circular welding print is greatly improved, and the resistivity is reduced.

[0081] Example 4

[0082] A cylindrical lithium battery, the positive electrode of which adopts the lithium battery positive electrode ear welding method based on the multi-weld print design described in any one of Examples 1-3.

Claims

1. A lithium battery positive electrode ear welding method based on a multi-weld stamp design, characterized in that: The following steps are involved: At least two weld marks are provided in the welding area between the positive electrode tab and the current collector, and the weld marks are distributed in a regular or irregular array.

2. The lithium battery positive electrode ear welding method based on the multi-weld stamp design according to claim 1, characterized in that: The weld mark is in the shape of a circle, an ellipse or a long strip, and the area of ​​a single weld mark is 0.5-2mm 2 The distance between adjacent weld marks is 0.3-1mm.

3. The lithium battery positive electrode ear welding method based on the multi-weld stamp design according to claim 2, characterized in that: Adopt the arrangement mode of multi-point welding print or multi-line welding print.

4. The lithium battery positive electrode ear welding method based on the multi-weld stamp design according to claim 3, characterized in that: The multi-spot welding print adopts a grid shape and a ring array.

5. The lithium battery positive electrode ear welding method based on the multi-weld stamp design according to claim 3, characterized in that: The multi-line weld prints use parallel lines.

6. The lithium battery positive electrode ear welding method based on the multi-weld stamp design according to claim 3, characterized in that: The multi-point welding or multi-line welding adopts a laser welding process or an ultrasonic welding process.

7. The lithium battery positive electrode ear welding method based on the multi-weld stamp design according to claim 3, characterized in that: The laser welding process includes the following steps: S1: Material preparation: positive electrode ear and current collector. The positive electrode ear is made of aluminum with a thickness of 0.2 mm. The current collector is made of aluminum foil with a thickness of 0.1 mm. S2: Welding print design: 3×3 grid welding print, single welding print diameter 1mm, spacing 0.5mm; S3: Through the laser welding process, the welding parameters of laser welding are as follows: laser power: 300W, pulse frequency: 50Hz, welding time: 0.1s per welding point.

8. The lithium battery positive electrode ear welding method based on a multi-weld stamp design according to claim 3, characterized in that: The ultrasonic welding process includes the following steps: S1: Material preparation: positive electrode ear and current collector. The positive electrode ear is made of aluminum with a thickness of 0.2 mm. The current collector is made of aluminum foil with a thickness of 0.1 mm. S2: Welding print design: parallel double-line welding print, line width 0.8mm, spacing 0.3mm; S3: Ultrasonic welding parameters are as follows: amplitude: 40 μm, pressure: 200 N, welding time: 0.5 s.

9. The lithium battery positive electrode ear welding method based on the multi-weld stamp design according to claim 3, characterized in that: The laser welding process includes the following steps: S1: Material preparation: positive electrode ear and current collector. The positive electrode ear is made of aluminum with a thickness of 0.2 mm. The current collector is made of aluminum foil with a thickness of 0.1 mm. S2: Welding mark design: adopt annular welding mark, the diameter of single welding mark is 1mm, 8 single welding marks are arranged on the inner ring, and the width of the ring is 2 single welding marks; S3: Through the laser welding process, the welding parameters of laser welding are as follows: laser power: 300W, pulse frequency: 50Hz, welding time: 0.1s per welding point.

10. A cylindrical lithium battery, characterized in that: The positive electrode adopts the lithium battery positive electrode ear welding method based on multi-welding design as described in any one of claims 1-9.

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