Battery shell welding method and battery shell

Abstract

The invention belongs to the technical field of battery manufacturing, and discloses a battery shell welding method and a battery shell. The battery shell comprises a cover plate and a shell, the cover plate comprises a body and a lap joint convex part, and the lap joint convex part is convexly arranged at the top of the peripheral side of the body; a containing cavity is formed in the shell and provided with an opening, the cover plate blocks the opening, the lap joint protruding part abuts against the top of the shell, and the outer edge of the lap joint protruding part is inwards staggered by a preset distance H relative to the outer edge of the side wall of the shell. And the lap joint convex part and the top of the body are fused and welded. For the cover plate provided with the lap joint convex part, after the outer edge of the lap joint convex part is inwards staggered by the preset distance H relative to the outer edge of the side wall of the shell, the lap joint convex part and the shell can be well welded by adopting a top welding method, so that the advantage of wide welding speed of top welding is reserved, and the advantage of side welding of preventing light from leaking into the battery is also achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery manufacturing, and in particular to a battery shell welding method and a battery shell. Background Art

[0002] In the welding process of square lithium battery shell cover, top welding and side welding are currently the main welding solutions. The battery weld of top welding is at the top, and its main advantage is fast speed. However, the laser beam leaks into the battery through the weld, and there is a risk of burning the core pack and causing battery short circuit. The battery weld of side welding is on the side, and a light shielding platform is designed in the battery shell cover structure to avoid the risk of laser leakage into the battery. However, during the side welding process, the battery needs to be turned over and welded in 4 sections. This welding method is inefficient. To improve efficiency, it is necessary to increase the number of lasers for simultaneous welding, which increases costs. In addition, during the side welding process, after the light shielding platform melts, there is a risk that the laser beam will hit the plastic on the pole, causing insulation failure.

[0003] Therefore, it is urgent to design a battery casing welding method and a battery casing to solve the above problems. Summary of the invention

[0004] An object of the present invention is to provide a battery shell welding method, which has the advantages of fast top welding speed and side welding to avoid light leakage into the battery.

[0005] Another object of the present invention is to provide a battery casing with a short manufacturing cycle and significantly reduced insulation failure during welding.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A battery shell welding method, the battery shell includes a cover plate and a shell, the cover plate includes a body and an overlapping convex portion, the overlapping convex portion is convexly arranged on the top of the peripheral side of the body; the shell forms a receiving cavity and has an opening, the cover plate blocks the opening, and the overlapping convex portion abuts against the top of the shell, the outer edge of the overlapping convex portion is staggered inwardly relative to the outer edge of the shell side wall to set a preset distance H, the battery shell welding method includes:

[0008] S10: The welding laser makes a circle from the top of the overlapping protrusion to melt and weld the overlapping protrusion to the top of the main body.

[0009] As an optional solution, the welding laser is offset inward by L1 relative to the outer edge of the overlapping protrusion during welding, and 0.1mm≤L1≤0.2mm.

[0010] As an optional solution, the thickness of the overlapping protrusion is T1, 0.2mm≤T1≤0.8mm.

[0011] As an optional solution, the total thickness of the cover plate is defined as T2, 0.4≤T1 / T2≤0.6.

[0012] As an optional solution, 1.0mm≤T2≤3.0mm.

[0013] As an optional solution, 0.1mm≤H≤0.2mm.

[0014] A battery shell is made by the above-mentioned battery shell welding method, wherein a vertical molten pool is formed at the welding position of the battery shell, and a protrusion height H2 of the molten pool at the top of the cover plate is 0 mm; and / or

[0015] The protrusion height of the above-mentioned molten pool on the side is 0mm≤H1≤0.1mm.

[0016] As an optional solution, the melting depth of the molten pool is L1, 1.1mm≤L1≤2.0mm.

[0017] As an optional solution, the effective melting depth of the molten pool is L3, 0.8mm≤L3≤1.3mm.

[0018] As an optional solution, the molten pool width is L2, 1.0mm≤L2≤2.0mm.

[0019] The beneficial effects of the present invention are:

[0020] The present invention provides a battery shell welding method. For a cover plate provided with an overlapping protrusion, the prior art adopts a side welding method for welding. For a square battery, welding needs to be performed in four sections. After the outer edge of the overlapping protrusion is staggered inwardly by a preset distance H relative to the outer edge of the shell side wall, a top welding method is adopted to better achieve the welding of the overlapping protrusion and the shell, which not only retains the advantage of a high welding speed of the top welding, but also has the advantage of avoiding light leakage to the inside of the battery of the side welding.

[0021] The present invention also provides a battery shell. By adopting the above-mentioned battery shell welding method for welding, the size of the battery shell is easier to ensure, which is convenient for subsequent assembly of PACK. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a partial cross-sectional view of a battery housing before welding provided by an embodiment of the present invention;

[0023] Figure 2 It is a partial cross-sectional view of a battery casing after welding provided by an embodiment of the present invention.

[0024] In the figure:

[0025] 10. Cover plate; 11. Main body; 12. Overlapping convex part;

[0026] 20. housing; 21. accommodating chamber;

[0027] 30. Molten pool; 40. Welding laser. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0029] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0031] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0032] This embodiment provides a battery shell welding method, which has the advantages of high efficiency of top welding and the advantage of side welding in preventing light leakage into the battery. Figure 1As shown, the battery shell includes a cover plate 10 and a shell 20, the cover plate 10 includes a main body 11 and an overlapping protrusion 12, the overlapping protrusion 12 is protruded from the top of the peripheral side of the main body 11; a accommodating cavity 21 is formed in the shell 20 and has an opening, the cover plate 10 blocks the opening, and the overlapping protrusion 12 abuts against the top of the shell 20, and the outer edge of the overlapping protrusion 12 is staggered inwardly by a preset distance H relative to the outer edge of the side wall of the shell 20. The battery shell welding method includes: S10: The welding laser 40 makes a circle from the top of the overlapping protrusion 12 to melt and weld the overlapping protrusion 12 to the top of the main body 11.

[0033] It can be understood that for the cover plate 10 provided with the overlapping protrusion 12, the prior art adopts the side welding method for welding. For the square battery, it needs to be welded in four sections. After the outer edge of the overlapping protrusion 12 is staggered inwardly by a preset distance H relative to the outer edge of the side wall of the shell 20, the top welding method can also better realize the welding of the overlapping protrusion 12 and the shell 20, which not only retains the advantage of the high welding speed of the top welding, but also has the advantage of the side welding to avoid light leakage into the battery.

[0034] Optionally, the welding laser 40 is offset inwardly by L1 relative to the outer edge of the overlapping protrusion 12 during welding, 0.1mm≤L1≤0.2mm; thus, a portion of the overlapping protrusion 12 is melted on both the inner and outer sides of the welding laser 40, so that the overlapping protrusion 12 and the top of the body 11 are melted more fully. Optionally, the value of L1 can be 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, etc.

[0035] Alternatively, if Figure 1 As shown, the thickness of the side wall of the shell 20 is defined as T3, 0.25mm≤T3≤0.8mm. Exemplarily, the thickness of the shell 20 is 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, etc. The shell 20 is thin and has poor structural strength, making it difficult to support the cover plate 10. The thick wall of the shell 20 causes the battery to be too heavy. This design has a moderate thickness and good structural strength.

[0036] Alternatively, if Figure 1 As shown, the thickness of the overlapping protrusion 12 is T1, 0.2mm≤T1≤0.8mm. When T1 is less than 0.2mm, since the overlapping protrusion 12 is the part that supports the cover plate 10, the strength at the connection position between the shell 20 and the overlapping protrusion 12 is insufficient, and it is easy to bend and deform. In addition, the overlapping protrusion 12 is the main part of the melting, and the design is too thin, resulting in insufficient melting and unstable welding. When T1 is greater than 0.8mm, it wastes raw materials, and during welding, the overlapping protrusion 12 is not easy to be welded through, which affects the welding effect.

[0037] Optionally, the total thickness of the cover plate 10 is defined as T2, 0.4≤T1 / T2≤0.6. After this design, on the one hand, if the ratio is set too low, the overlapping protrusion 12, as the part that supports the cover plate 10, is easily bent and deformed at the connection position between the shell 20 and the overlapping protrusion 12. On the other hand, if the ratio is set too high, it will waste raw materials. During welding, the overlapping protrusion 12 is not easy to be welded through, which affects the welding effect. For example, T1 / T2=0.4, 0.45, 0.5, 0.55, 0.6 and other values.

[0038] Optionally, 1.0mm≤T2≤3.0mm. Exemplarily, the thickness of the cover plate 10 is 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, etc. The cover plate 10 is thin and has poor structural strength, making it difficult to support other structures on the cover plate 10, thereby reducing the bending strength of the cover plate 10, making it difficult to ensure the flatness of the cover plate 10, and there is a possibility that during laser welding, there will be less remaining material, and the laser will penetrate into the battery, causing short circuits and other problems. The thicker the cover plate 10, the heavier the battery. The cover plate 10 of this design has a moderate thickness, a lighter structure, good structural strength, is not easy to deform, and has guaranteed flatness.

[0039] It is understandable that after the side wall of the housing 20 and the overlapping protrusion 12 are welded, a Figure 2 The shape of the molten pool 30 determines the external dimensions of the final battery housing. The protrusion of the molten pool 30 on the top surface of the cover plate 10 and the side surface of the shell 20 determines the external dimensions of the battery housing.

[0040] Optionally, 0.1mm≤H≤0.2mm, when the offset distance exceeds 0.25mm, the contact area between the overlapping protrusion 12 and the shell 20 is insufficient, which will reduce the firmness of the welding. When the offset distance is less than 0.1mm, the effect of reducing the protrusion is not obvious. Exemplarily, H=0.1mm, 0.13mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm and other values. Combined with the distance of the welding laser 40 offset inward, the protrusion height of the molten pool 30 on the side wall of the shell 20 is further reduced.

[0041] This embodiment also provides a battery shell, which is made by the above-mentioned battery shell welding method. Figure 2 As shown, the protrusion height H2 of the molten pool 30 on the top of the cover plate 10 is 0 mm; for ease of understanding, Figure 2In the figure, the height of the molten pool 30 protruding from the cover plate 10 is defined as L3. In the prior art, this value is a positive value. When the overlapping protrusion 12 and the outer edge of the shell 20 are staggered by a distance H, the protrusion at this position disappears after the top welding test, ensuring the flatness and dimensional accuracy of the top of the cover plate 10. That is to say, in this embodiment, H2 indicated in the figure does not exist.

[0042] Optionally, the protrusion height of the molten pool 30 on the side is 0mm≤H1≤0.1mm, that is, after testing, the height of the molten pool 30 protruding from the side of the battery casing is also reduced. In the prior art, the protrusion of the side is about 0.3mm. Through the design of this embodiment, after top welding, a better effect can be achieved without forming a protrusion, and most of them are within 0.1mm, which are within the tolerance range of the battery casing size. Exemplarily, the value of H1 is 0.02mm, 0.05mm, 0.07mm, 0.1mm, etc. Since the size of the battery casing is within the tolerance range, the battery casing is also easier to assemble during the subsequent PACK assembly.

[0043] Alternatively, if Figure 2 As shown, the melting depth of the molten pool 30 is L1, 1.1mm≤L1≤2.0mm. Through the above setting, the depth of the deepest position of the molten pool 30 is ensured to be within this range. At this time, the depth is about ten times of H, ensuring that the material at the welding position is fully melted. Exemplarily, the value of L1 can be 1.0mm, 1.2mm, 1.5mm, 1.7mm, 1.9mm, 2.0mm, etc.

[0044] Alternatively, if Figure 2 As shown, the effective penetration depth of the molten pool 30 is L3, 0.8mm≤L3≤1.3mm, wherein the effective penetration depth means the portion where the cover plate 10 and the shell 20 are fused together, that is, the portion where the molten pool 30 melts the shell 20 on one side is removed. Through the above arrangement, it is ensured that the cover plate 10 and the shell 20 are fully melted during welding. That is to say, the effective penetration depth L3 must be greater than the value of T1. Exemplarily, the value of L3 can be 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3, etc.

[0045] Alternatively, if Figure 2 As shown, the molten pool 30 has a molten width L2, 1.0 mm ≤ L2 ≤ 2.0 mm. Under this premise, L2 needs to be greater than T3 and also greater than the distance of the overlapping protrusion 12 protruding from the body 11. Through the above arrangement, the cover plate 10 and the shell 20 are fully melted, and the welding bonding stability is improved. For example, the value of L2 can be 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm, 1.9 mm, etc.

[0046] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A battery casing welding method, characterized in that: A battery shell comprises a cover plate (10) and a shell (20), the cover plate (10) comprising a body (11) and an overlapping protrusion (12), the overlapping protrusion (12) being convexly arranged on the top of the peripheral side of the body (11); a receiving cavity (21) is formed in the shell (20) and has an opening, the cover plate (10) blocks the opening, and the overlapping protrusion (12) abuts against the top of the shell (20), and the outer edge of the overlapping protrusion (12) is staggered inwardly by a preset distance H relative to the outer edge of the side wall of the shell (20), and the battery shell welding method comprises: S10: The welding laser (40) makes a circle from the top of the overlapping protrusion (12) to melt-weld the overlapping protrusion (12) and the top of the body (11).

2. The battery casing welding method according to claim 1, characterized in that: During welding, the welding laser (40) is offset inward by L1 relative to the outer edge of the overlapping protrusion (12), and 0.1 mm≤L1≤0.2 mm.

3. The battery casing welding method according to claim 1, characterized in that: The thickness of the overlapping protrusion (12) is T1, 0.2mm≤T1≤0.8mm.

4. The battery casing welding method according to claim 3, characterized in that: The total thickness of the cover plate (10) is defined as T2, 0.4≤T1 / T2≤0.

6.

5. The battery casing welding method according to claim 4, characterized in that: 1.0mm≤T2≤3.0mm.

6. The battery casing welding method according to any one of claims 1 to 5, characterized in that: 0.1mm≤H≤0.2mm.

7. A battery housing, characterized in that: The battery shell is manufactured by the battery shell welding method according to any one of claims 1 to 6, wherein a vertical molten pool (30) is formed at the welding position of the battery shell, and a protrusion height H2 of the molten pool (30) on the top of the cover plate (10) is 0 mm; and / or The protrusion height of the molten pool (30) on the side is 0mm≤H1≤0.1mm.

8. The battery casing according to claim 7, characterized in that: The melting depth of the molten pool (30) is L1, 1.1 mm ≤ L1 ≤ 2.0 mm.

9. The battery casing according to claim 8, characterized in that: The effective melting depth of the molten pool (30) is L3, 0.8 mm ≤ L3 ≤ 1.3 mm.

10. The battery housing according to claim 7, characterized in that: The molten pool (30) has a molten width L2, 1.0 mm ≤ L2 ≤ 2.0 mm.

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