Steel can button cell and welding process method thereof

Abstract

The application discloses a steel shell button type battery and a welding process method thereof and belongs to the technical field of batteries. The method comprises the following steps: S1, fixing the overlapping position of the upper shell and the lower shell to a welding fixture, reserving a gap position, and injecting nitrogen at the overlapping position of the upper shell and the lower shell, so that the nitrogen is wrapped at the circumferential welding position; S2, idling the welding fixture; S3, starting first-stage laser welding, reserving a gap for pressure relief, wherein the welding circumference is 93%-98% of the total circumference length; S4, entering a welding delay stage, keeping sufficient pressure relief time, and letting the gasified electrolyte completely overflow; and S5, starting second-stage laser welding and laser welding the reserved gap. The method reserves a gap for welding, the gas in the shell is discharged in the welding delay stage, and the gasified electrolyte is discharged, so that the laser high temperature is prevented from being welded to the accumulated electrolyte, and explosion is prevented.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a steel-cased button cell battery and its welding process. Background Technology

[0002] As laser welding technology matures, it is widely used in the processing of metal, glass, and plastic products, and its application in the battery field is becoming increasingly widespread. Currently, the welding of stainless steel button battery casings suffers from the problem of "explosion points," where the laser beam welds onto accumulated electrolyte, creating tiny ignition points. Conventional welding methods use a constant power, continuous laser welding, resulting in a high rate of defective welds with explosion points, posing a risk of leakage and affecting battery performance and lifespan. Furthermore, the welding process is affected by the electrolyte, causing localized protrusions or dents in the casing. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0004] A steel-cased button cell battery, comprising:

[0005] The housing is cylindrical; the housing includes an upper shell and a lower shell, the upper shell is sleeved on the outer side of the upper end of the lower shell and welded to the lower shell to form a sealed cavity;

[0006] A core is disposed within the cavity. The core includes a first tab and a second tab. The first tab is fixedly connected to the upper shell, and the second tab is fixedly connected to the lower shell.

[0007] Electrolyte, which is injected into the cavity.

[0008] Furthermore, a gap of 1~50um is reserved between the shell wall of the upper shell and the shell wall of the lower shell.

[0009] Furthermore, the circumferential position where the upper shell and the lower shell meet is subjected to segmented laser welding to form a sealed cavity.

[0010] The welding of the steel-cased button cell, using a segmented laser welding process, includes the following steps:

[0011] S1, fix the overlapping position of the upper shell and the lower shell onto the welding fixture, leave a notch, inject nitrogen gas at the overlapping position of the upper shell and the lower shell so that the nitrogen gas surrounds the circumferential welding position.

[0012] S2, the welding fixture is idling;

[0013] S3, begin the first stage of laser welding, with a welding circumference of 93%-98% of the total circumference of the circle, leaving a notch for pressure relief;

[0014] S4, enter the welding delay stage, maintain sufficient depressurization time to allow the vaporized electrolyte to completely overflow;

[0015] S5, begin the second stage of laser welding, and perform laser welding on the reserved gap.

[0016] Furthermore, in step S2, the welding fixture idles at a speed of 150 mm / s, and the idle delay time is set to 3000 ms.

[0017] Furthermore, in step S3, the first laser welding time gradually increases from 0 to 10 ms, with the power starting at 40 W and ending at 33.5 W; the time gradually increases from 10 to 50 ms, with the power maintained at 33.5 W; the time increases from 50 ms to 150 ms, with the power starting at 33.5 W and ending at 32 W.

[0018] Furthermore, in step S4, the welding delay stage begins, with a delay time of 355ms, to maintain sufficient pressure relief time and allow the vaporized electrolyte to completely overflow.

[0019] Furthermore, in step S5, the second stage of laser welding involves a time interval from 0ms to 4ms, with the power increasing from 0W to 35.5W; a time interval from 4ms to 44ms, with the power maintained at 33.5W; a time interval from 44ms to 47ms, with the power increasing from 35.5W to 20W; and a time interval from 47ms to 52ms, with the power decreasing from 20W to 0W. This process fills the pre-reserved gap with a welded circumference ≥ 10%-15% of the total circumference.

[0020] In step S3, the diameter Ra of the first weld point is less than or equal to the diameter Rb of the second weld point in step S5, so that the welding position of the second segment completely covers the gap reserved for welding in the first segment.

[0021] Furthermore, the diameter Ra of the first solder joint is 0.05 mm, and the diameter Rb of the second solder joint is 0.07 mm.

[0022] Beneficial effects:

[0023] This invention provides a segmented laser welding process that, by leaving a notch in the weld, delays the release of gas and vaporized electrolyte from the casing, preventing the high-temperature laser from welding onto the accumulated electrolyte and thus preventing explosion points. This solves the problem of explosion points during laser welding at the circumference of steel-cased batteries, increasing the circumferential welding yield from 70% to 99%, significantly reducing production costs and the risk of leaking defective products. Furthermore, the segmented welding results in more uniform weld seams, with no protrusions or depressions, leading to a more aesthetically pleasing product. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of a steel-cased button cell battery.

[0025] Figure 2 This is a top view of a steel-cased button cell battery.

[0026] Figure 3 This is a schematic diagram of the structure of a steel-cased button cell battery.

[0027] Figure 4 This is a schematic diagram of the core structure of a steel-cased button cell.

[0028] Figure 5 These are the welding parameters for the first segment.

[0029] Figure 6 These are the welding parameters for the second segment.

[0030] Wherein: 1-upper shell; 2-lower shell; 3-core; 4-first electrode tab; 5-second electrode tab; 6-laser welding position. Detailed Implementation

[0031] The technical solutions of various embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0033] Example 1

[0034] A steel-cased button cell battery, comprising:

[0035] The shell is cylindrical; the shell includes an upper shell 1 and a lower shell 2. The upper shell 1 is fitted onto the upper outer side of the lower shell 2 and welded to the lower shell 2 to form a sealed cavity.

[0036] The core 3 is disposed in the cavity. The core 3 includes a first tab 4 and a second tab 5. The first tab 4 is fixedly connected to the upper shell 1, and the second tab 5 is fixedly connected to the lower shell 2.

[0037] Electrolyte is injected into the cavity.

[0038] Preferably, a gap of 1~50um is reserved between the shell wall of the upper shell 1 and the shell wall of the lower shell 2.

[0039] Preferably, the circumferential position where the upper shell 1 and the lower shell 2 meet is laser welded in segments to form a sealed cavity; the instantaneous temperature of the laser-welded steel shell is as high as 1375-1450℃. During the welding process, the internal temperature of the battery rises, the electrolyte vaporizes, and the vaporized electrolyte will overflow from the gap between the upper and lower shells along with the internal gas.

[0040] Example 2

[0041] This embodiment describes the segmented laser welding process for a steel-cased button cell provided in Embodiment 1. The segmented laser welding process includes the following steps:

[0042] S1, fix the overlapping position of the upper and lower shells onto the welding fixture, leave a notch, and inject nitrogen gas at the overlapping position of the upper and lower shells so that the nitrogen gas surrounds the circumferential welding position; the role of nitrogen gas is to prevent the high temperature of laser welding from burning with oxygen in the air.

[0043] S2, the welding fixture is idling;

[0044] S3, begin the first stage of laser welding, with a welding circumference of 93%-98% of the total circumference of the circle, leaving a notch for pressure relief;

[0045] S4, enter the welding delay stage, maintain sufficient depressurization time to allow the vaporized electrolyte to completely overflow;

[0046] S5, begin the second stage of laser welding, and perform laser welding on the reserved gap.

[0047] In this embodiment, in step S2, the welding fixture idles at a speed of 150 mm / s, and the idle delay time is set to 3000 ms.

[0048] In this embodiment, in step S3, the first laser welding time gradually increases from 0 to 10 ms, with the power starting at 40 W and ending at 33.5 W; the time gradually increases from 10 to 50 ms, with the power maintained at 33.5 W; the time increases from 50 ms to 150 ms, with the power starting at 33.5 W and ending at 32 W; the initial stage of welding requires preheating of the housing, and as the housing temperature rises, the welding power gradually decreases.

[0049] In this embodiment, step S4 enters the welding delay stage with a delay time of 355ms, maintaining sufficient pressure relief time to allow the vaporized electrolyte to completely overflow.

[0050] In this embodiment, in step S5, the second laser welding process involves a time interval from 0ms to 4ms, with the power increasing from 0W to 35.5W; a time interval from 4ms to 44ms, with the power maintained at 33.5W; a time interval from 44ms to 47ms, with the power increasing from 35.5W to 20W; and a time interval from 47ms to 52ms, with the power decreasing from 20W to 0W, thus filling the pre-reserved gap. The welded circumference is ≥ 10%-15% of the total circumference.

[0051] In step S3, the diameter Ra of the first weld point is less than or equal to the diameter Rb of the second weld point in step S5, so that the welding position of the second segment completely covers the gap reserved for welding in the first segment.

[0052] This ensures that the second welding position completely covers the gap left in the first welding section.

[0053] In this embodiment, the diameter Ra of the first solder joint is 0.05 mm, and the diameter Rb of the second solder joint is 0.07 mm.

[0054] This embodiment provides a segmented laser welding process method. By leaving a notch in the welding, the gas and vaporized electrolyte in the shell are released in a delayed manner, preventing the high temperature of the laser from welding onto the accumulated electrolyte and preventing explosion points. This solves the problem of explosion points in the laser welding of the circumference of steel-shell batteries. At the same time, the segmented welding results in more uniform weld seams, no protrusions or depressions in the weld points, and a more aesthetically pleasing product.

[0055] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A segmented laser welding process method, characterized in that, The segmented laser welding process includes the following steps: S1, fix the overlapping position of the upper shell and the lower shell onto the welding fixture, leave a notch, inject nitrogen gas at the overlapping position of the upper shell and the lower shell so that the nitrogen gas surrounds the circumferential welding position. S2, the welding fixture is idling; S3, begin the first stage of laser welding, with a welding circumference of 93%-98% of the total circumference of the circle, leaving a notch for pressure relief; S4, enter the welding delay stage, maintain sufficient depressurization time to allow the vaporized electrolyte to completely overflow; S5, begin the second stage of laser welding, and perform laser welding on the reserved gap; The steel-cased button cell used for welding by the segmented laser welding process described above comprises: The housing is cylindrical; the housing includes an upper shell and a lower shell, the upper shell is sleeved on the outer side of the upper end of the lower shell and welded to the lower shell to form a sealed cavity; A core is disposed within the cavity. The core includes a first tab and a second tab. The first tab is fixedly connected to the upper shell, and the second tab is fixedly connected to the lower shell. Electrolyte, which is injected into the cavity; A gap of 1 to 50 μm is reserved between the shell wall of the upper shell and the shell wall of the lower shell; The upper shell and the lower shell are joined at a circumferential position by segmented laser welding to form a sealed cavity.

2. The segmented laser welding process method as described in claim 1, characterized in that, In step S2, the welding fixture is idled at a speed of 150 mm / s, and the idle delay time is set to 3000 ms.

3. The segmented laser welding process method as described in claim 2, characterized in that, In step S3, the first laser welding time gradually increases from 0 to 10 ms, with the power starting at 40 W and ending at 33.5 W; the time gradually increases from 10 to 50 ms, with the power maintained at 33.5 W; the time gradually increases from 50 ms to 150 ms, with the power starting at 33.5 W and ending at 32 W.

4. The segmented laser welding process method as described in claim 3, characterized in that, In step S4, the welding delay stage begins, with a delay time of 355ms, allowing sufficient time for depressurization to ensure that the vaporized electrolyte completely overflows.

5. The segmented laser welding process method as described in claim 4, characterized in that, In step S5, the second laser welding process involves the following steps: the time ranges from 0ms to 4ms, with the power increasing from 0W to 35.5W; the time ranges from 4ms to 44ms, with the power maintained at 33.5W; the time ranges from 44ms to 47ms, with the power increasing from 35.5W to 20W; and the time ranges from 47ms to 52ms, with the power decreasing from 20W to 0W. This process fills the pre-reserved gap with welded circumferences ≥ 10%-15% of the total circumference. In step S3, the diameter Ra of the first weld point is less than or equal to the diameter Rb of the second weld point in step S5, so that the welding position of the second segment completely covers the gap reserved for welding in the first segment.

6. The segmented laser welding process method as described in claim 5, characterized in that, The diameter Ra of the first solder joint is 0.05 mm, and the diameter Rb of the second solder joint is 0.07 mm.

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