Battery shell, single battery and production method of single battery

Abstract

The invention provides a battery shell, a single battery and a production method thereof, and the battery shell comprises a bottom shell which is provided with an opening end, and a welding reference surface is annularly arranged on the bottom shell along the opening end; the top cover is arranged on the bottom shell and used for blocking the opening end, the top cover is in lap joint with the welding datum plane, a sealing face annularly arranged along the opening end is arranged on the inner side of the top cover, and the sealing face abuts against or is attached to the inner wall of the bottom shell and / or the welding datum plane; a welding seam between the top cover and the bottom shell is positioned in a sealing surface area; an annular groove is annularly formed in the top cover along the opening end, and the area, corresponding to the annular groove, on the inner side face of the top cover belongs to a sealing face. According to the battery shell, the welding seam of the top cover and the bottom shell can be arranged close to one side of the annular sealing groove as far as possible, and the upper preassembled flange and the lower preassembled flange can be cut as much as possible under the condition that the sealing performance is not changed, so that the volume of the battery shell is reduced to a certain extent, and the energy density of a single battery applied to the battery shell is favorably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery casing, a single battery and a production method thereof. Background Art

[0002] The existing lithium-ion battery structure generally includes a bottom shell and a top cover welded to each other, and the bottom shell and the top cover are welded to form a sealed cavity for accommodating the battery cell.

[0003] A Chinese patent with publication number CN215644674U discloses a battery housing and a battery, wherein the battery housing comprises a bottom housing and a top cover, wherein the bottom housing comprises a connected bottom wall and an annular side wall, wherein the end of the side wall facing away from the bottom wall has an opening, the top cover is arranged on the end face of the opening, and a side cover is arranged around the outer side of the opening; the annular side cover is welded to the top cover, and a weld is provided on a side of the top cover facing away from the side cover, wherein the weld comprises a plurality of connected and partially overlapping welding sections.

[0004] In the above patent, in order to ensure that the top cover and the bottom shell have a sufficiently large contact area for welding, the side cover width is relatively large, which makes the battery shell larger in the radial direction of the side wall, thereby increasing the volume of the single cell. Under the same volume, the energy density of the single cell formed by the battery shell is low. Summary of the invention

[0005] In view of the deficiencies of the prior art, a first object of the present invention is to provide a battery casing, wherein the weld between the top cover and the bottom shell can be closer to the center position of the top cover in the radial direction of the bottom shell, which is conducive to reducing the size of the battery casing.

[0006] The second object of the present invention is to provide a single cell with small volume and high energy density.

[0007] The third object of the present invention is to provide a single cell production method, which can produce single cells with high sealing performance and high energy density.

[0008] The embodiments of the present invention are implemented by the following technical solutions:

[0009] A battery housing, comprising: a bottom case having an open end, and a welding reference surface is annularly provided along the open end on the bottom case; a top cover disposed on the bottom case for sealing the open end, the top cover overlapping the welding reference surface, and a sealing surface is annularly provided along the open end on the inner side of the top cover, and the sealing surface abuts or fits against the inner wall of the bottom case and / or the welding reference surface; the top cover is welded to the bottom case, and the weld between the two is within the area of the sealing surface; an annular groove is annularly provided along the open end on the top cover, and the area corresponding to the annular groove on the inner side surface of the top cover belongs to the sealing surface. In this way, the area of the sealing surface corresponding to the annular groove can reduce or make zero the gap between the sealing surface and the inner wall of the bottom case and / or the welding reference surface, and the weld between the top cover and the bottom case can be arranged as close as possible to one side of the annular sealing groove. Under the condition of unchanged sealing performance, as much as possible of the upper pre-installed flange and the lower pre-installed flange can be cut, which reduces the volume of the battery housing to a certain extent and is beneficial to improving the energy density of the single battery applied to the battery housing.

[0010] According to a preferred embodiment, the annular groove is provided on the outer side surface of the top cover, and the annular groove is recessed in the direction towards the bottom case.

[0011] According to a preferred embodiment, the depth of the annular groove is H = 0.3 mm - 0.4 mm, the maximum width of the annular groove is D, D = 0.9 mm - 1.0 mm, and D / H = 2.25 - 3.33.

[0012] According to a preferred embodiment, the annular groove is an arc groove.

[0013] According to a preferred embodiment, an arc transition section is formed between the welding reference surface and the inner wall of the bottom case, and the sealing surface abuts or fits against the arc transition section; the arc transition section is arc-shaped, and its radius is R, R = 0.28 mm - 0.32 mm, and R / H = 0.7 - 1.067.

[0014] According to a preferred embodiment, the weld is annularly arranged along the annular groove, and the minimum distance between the weld and the center of the bottom of the annular groove is L, L == 0.2 mm - 0.3 mm.

[0015] According to a preferred embodiment, the weld is annularly arranged along the annular groove, and part or all of the weld is on the inner wall of the annular groove.

[0016] According to a preferred embodiment, the open end of the bottom case is configured with a lower pre-installation flange extending outward in the horizontal direction. The area of the top cover outside the annular groove constitutes an upper pre-installation flange corresponding to the lower pre-installation flange. There is a dissipation gap between the upper pre-installation flange and the lower pre-installation flange, and the dissipation gap extends to the outer edge of the weld seam.

[0017] A single cell includes a battery core and the aforementioned battery case, and the battery core is disposed within the battery case. This single cell has high safety and a greater energy density compared to the same type and volume of batteries in the prior art.

[0018] A method for manufacturing a single cell, applied to the aforementioned single cell, includes the following steps: disposing the battery core within the bottom case and covering the top cover on the open end of the bottom case; bringing the sealing surface close to or into contact with the inner wall of the bottom case and / or the welding reference surface; welding the top cover and the bottom case, with the welding path close to or within the annular groove area to form a weld seam; cutting off the excess material of the top cover and the bottom case outside the weld seam.

[0019] Based on the above steps, the area of the sealing surface corresponding to the annular groove can reduce or make zero the gap between the sealing surface and the bottom case. After welding the top cover and the bottom case, the weld seam can be arranged as close as possible to one side of the annular sealing groove or within the annular groove area, so that as much area of the battery case outside the weld seam can be cut off as possible while maintaining the sealing performance, reducing the volume of the battery case, which is beneficial to improving the energy density of the single cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a three-dimensional structural schematic diagram of the battery case provided by the embodiment of the present invention;

[0022] Figure 2 It is an exploded structural schematic diagram of the battery case provided by the embodiment of the present invention;

[0023] Figure 3 It is a top-view structural schematic diagram of the battery case provided by the embodiment of the present invention;

[0024] Figure 4 For Figure 3 the cross-sectional view along A-A in

[0025] Figure 5 For Figure 4 a partial enlarged schematic view of the structure at position B in

[0026] Figure 6 Another assembly structure of the top cover and the bottom case of a battery case provided by an embodiment of the present invention.

[0027] Icon: 1 - top cover, 10 - upper pre - installation flange, 11 - annular groove, 12 - sealing surface, 2 - bottom case, 20 - lower pre - installation flange, 21 - arc transition section, 22 - welding reference surface, 3 - dissipation gap, 4 - welding area. Specific embodiments

[0028] For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0029] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0031] Please refer to Figures 1 to 6 , a battery case includes a bottom case 2 and a top cover 1. The bottom case 2 has an open end, and a welding reference surface 22 is provided around the open end of the bottom case 2. The top cover 1 is disposed on the bottom case 2 to block the open end. The top cover 1 overlaps the welding reference surface 22. An annular sealing surface 12 is provided along the open end inside the top cover 1. The sealing surface 12 abuts or fits against the inner wall of the bottom case 2 and / or the welding reference surface 22. The top cover 1 and the bottom case 2 are welded, and the weld between them is within the area of the sealing surface 12. An annular groove 11 is provided along the open end of the top cover 1, and the area corresponding to the annular groove 11 on the inner surface of the top cover 1 belongs to the sealing surface 12. As Figure 1 and Figure 2As shown, it is the blank state of the battery housing provided in this embodiment. Specifically, for the convenience of assembly, the open end of the bottom shell 2 is provided with a lower pre-assembly flange 20 extending outward in the horizontal direction. The area of the top cover 1 outside the annular groove 11 forms an upper pre-assembly flange 10 corresponding to the lower pre-assembly flange 20. The path trajectory of the weld extends along the annular groove 11. After the bottom shell 2 and the top cover 1 are welded, the upper pre-assembly flange 10 and the lower pre-assembly flange 20 outside the weld are cut to form the battery housing. In this embodiment, the area of the sealing surface 12 corresponding to the annular groove 11 can reduce or make zero the gap between the sealing surface 12 and the inner wall of the bottom shell 2 and / or the welding reference surface 22. Thus, during the welding process of the top cover 1 and the bottom shell 2, the weld can be arranged as close as possible to the side of the annular sealing groove. After welding is completed, under the condition of unchanged sealing performance, as much of the upper pre-assembly flange 10 and the lower pre-assembly flange 20 can be cut as possible, which reduces the volume of the battery housing to a certain extent and is beneficial to improving the energy density of the single battery applied to this battery housing.

[0032] In this embodiment, both the bottom shell 2 and the top cover 1 are made by stamping process. The annular groove 11 here can improve the strength of the top cover 1. At the same time, the annular groove 11 is distributed close to the edge of the open end of the bottom shell 2, so it has little influence on the volume of the inner cavity of the bottom shell 2 and does not affect the assembly of the battery core in the battery housing.

[0033] In this embodiment, the annular groove 11 is arranged on the outer side surface of the top cover 1 and is recessed in the direction towards the bottom shell 2.

[0034] As Figure 5 shown, the depth of the annular groove 11 is H, H = 0.3mm - 0.4mm, the maximum width of the annular groove 11 is D, D = 0.9mm - 1.0mm, D / H = 2.25 - 3.33. Preferably, D / H = 3. With such a setting, while ensuring that the sealing surface 12 can have a large enough contact area with the bottom shell 2, it can also reduce the occupation of the volume of the inner cavity of the bottom shell 2 by the annular groove 11, ensuring the welding sealability of the top cover 1 and the bottom shell 2 and reducing the volume of the battery housing without affecting the assembly of the battery core.

[0035] Optionally, the annular groove 11 is an arc groove. It is convenient for stamping, and at the same time, the stress concentration at the edge of the annular groove 11 is small, and the strength of the top cover 1 is higher.

[0036] As Figure 5 and Figure 6As shown, an arc transition section 21 is formed between the welding reference surface 22 and the inner wall of the bottom case 2, and the sealing surface 12 abuts against or fits to the arc transition section 21. In this embodiment, it can be understood that the area of the arc transition section 21 close to the welding reference surface 22 belongs to the welding reference surface 22, and the area of the arc transition section 21 close to the inner wall of the bottom case 2 belongs to the inner wall of the bottom case 2. The arc transition section 21 here is convenient for adapting to the aforementioned circular arc-shaped annular groove 11. Preferably, the sealing surface 12 fits to the arc transition section 21. It should be noted that the so-called fitting of the sealing surface 12 to the arc transition section 21 means that there is an area where the sealing surface 12 and the arc transition section 21 fit to each other, that is, there is an area belonging to the sealing surface 12 and an area belonging to the arc transition section 21 that fit to each other, and it is not required that the entire area of the sealing surface 12 fits to the entire area of the arc transition section 21.

[0037] Of course, in other embodiments, it is also allowed that the sealing surface 12 and the arc transition section 21 are in a non-fitting state. At this time, it is required that the gap between the two is small enough not to affect laser welding.

[0038] In the above situation, in order to further reduce the volume of the battery case, preferably, the sealing surface 12 fits to the area of the arc transition section 21 close to the inner wall of the case, that is, the sealing surface 12 fits to the inner wall of the bottom case 2, so that the weld seam can be further closer to the center direction of the top cover 1, which means that more of the upper pre-installed flange 10 and the lower pre-installed flange 20 can be cut.

[0039] In this embodiment, as Figure 5 shown, the arc transition section 21 is arc-shaped, its radius is R, R = 0.28 mm - 0.32 mm, R / H = 0.7 - 1.067, preferably, R / H = 1. In this way, the annular groove 11 sinks into the bottom case 2 deep enough longitudinally to ensure that there is a large enough mating area (welding area 4 available for welding operation) between the sealing surface 12 and the arc transition section 21 without affecting the assembly of the battery cell inside the bottom case 2.

[0040] As Figure 6 shown, in some embodiments, there is a dissipation gap 3 between the upper pre-installed flange 10 and the lower pre-installed flange 20, and the dissipation gap 3 extends to the outer edge of the weld seam. During the welding process, especially during the penetration welding process, a large amount of heat will be generated on the top cover 1 and the bottom case 2, and the air between the top cover 1 and the bottom case 2 will be heated and expanded. The dissipation gap 3 here helps this part of the high-temperature air to dissipate outside the battery case, preventing it from carrying welding slag into the battery case through the gap between the top cover 1 and the bottom case 2 and causing battery short circuit. At the same time, during the laser welding process, the dissipation gap 3 also provides more dissipation channels for the hot air in the keyhole or molten pool, which helps to reduce pores and improve the welding quality.

[0041] AsFigure 5 and 6 As shown in 6 , the weld seam is arranged in a ring along the annular groove 11. The minimum distance between the weld seam and the center of the bottom of the annular groove 11 is L, where L = 0.2 mm - 0.3 mm. Preferably, L = 0.2 mm.

[0042] Optionally, the weld seam is arranged in a ring along the annular groove 11, and part or all of the weld seam is located on the inner wall of the annular groove 11. Preferably, the entire weld seam is located on the inner wall of the annular groove 11. As Figure 5 and Figure 6 shown in Figure 6 , the welding operation is performed within the welding area 4. Specifically, a laser beam can be projected from the side of the annular groove 11 for welding, or a laser beam can be projected from the outer wall side of the bottom case 2 for welding. When welding from the side of the annular groove 11, the keyhole penetrates the side wall of the top cover 1 and can penetrate or not penetrate the side wall of the bottom case 2; when welding from the side of the bottom case 2, the keyhole penetrates the side wall of the bottom case 2 and can penetrate or not penetrate the side wall of the top cover 1.

[0043] In the case where the annular groove 11 is provided, the weld seam on the side of the top cover 1 is located within the annular groove 11, and the overall height is lower than the highest height of the upper side surface of the top cover 1. Therefore, there is no need to further process the weld seam here, such as operations like rolling, etc., which simplifies the production and processing procedure of the single cell using this battery case. Correspondingly, on the side of the bottom case 2, the weld seam is located at the transition between the lower pre - installed flange 20 and the outer wall of the bottom case 2, which is an arc - shaped concave structure. Therefore, the weld seam on the side of the bottom case 2 also does not need to be further processed, further simplifying the production and processing procedure.

[0044] It should be noted that in some embodiments, preferably, the welding area 4 is located at the transition between the upper edge of the bottom case 2 and the lower pre - installed flange 20. The aforementioned dissipation gap 3 communicates with the welding area 4.

[0045] This embodiment also provides a single cell, including an electric core (not shown in the figure) and the aforementioned battery case, and the electric core is arranged within the battery case. Due to the high sealing performance and small volume of the aforementioned battery case, the single cell has high safety and a larger energy density compared to the same - type and same - volume batteries in the prior art.

[0046] This embodiment also provides a method for manufacturing a single cell, which is applied to the aforementioned single cell and includes the following steps:

[0047] Step S1: Place the electric core within the bottom case 2 and cover the top cover 1 on the open end of the bottom case 2;

[0048] Step S2: Press the sealing surface 12 close to or against the inner wall of the bottom case 2 and / or the welding reference surface 22;

[0049] Step S3: Weld the top cover 1 and the bottom case 2, and the welding path is close to or within the area of the annular groove 11 to form a weld seam;

[0050] Step S4: Cut the excess material outside the weld of the top cover 1 and the bottom case 2.

[0051] In this way, the area of the sealing surface 12 corresponding to the annular groove 11 can reduce or make zero the gap between the sealing surface 12 and the bottom case 2. After welding the top cover 1 and the bottom case 2, the weld can be arranged as close as possible to the side of the annular sealing groove or in the area of the annular groove 11, so that under the condition of unchanged sealing performance, as much area outside the weld on the battery case can be cut as possible, reducing the volume of the battery case and being beneficial to improving the energy density of the single battery.

[0052] Preferably, a laser is used to weld the battery case.

[0053] Preferably, the top cover 1 and the bottom case 2 are penetrated and welded.

[0054] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A battery housing, characterized in that: include: A bottom shell having an open end, wherein a welding reference surface is provided on the bottom shell along the open end; A top cover, arranged on the bottom shell, used to block the opening end, the top cover overlaps the welding reference surface, the inner side of the top cover is provided with a sealing surface arranged along the opening end, the sealing surface is close to or attached to the inner wall of the bottom shell and / or the welding reference surface; The top cover is welded to the bottom shell, and the weld between the two is located in the sealing surface area; The top cover is provided with an annular groove along the opening end, and the area on the inner side surface of the top cover corresponding to the annular groove belongs to the sealing surface.

2. The battery housing according to claim 1, characterized in that: The annular groove is arranged on the outer side surface of the top cover, and the annular groove is recessed toward the bottom shell.

3. The battery housing according to claim 1 or 2, characterized in that: The depth of the annular groove is H=0.3mm-0.4mm, the maximum width of the annular groove is D, D=0.9mm-1.0mm, and D / H=2.25-3.

33.

4. The battery housing according to claim 1 or 2, characterized in that: The annular groove is a circular arc groove.

5. The battery housing according to claim 1 or 2, characterized in that: An arc-shaped transition section is formed between the welding reference surface and the inner wall of the bottom shell, and the sealing surface is close to or fits the arc-shaped transition section; the arc-shaped transition section is arc-shaped, and its radius is R, R=0.28mm-0.32mm, R / H=0.7-1.

067.

6. The battery casing according to claim 5, characterized in that: The welding seam is arranged along the annular groove, and the minimum distance between the welding seam and the bottom center of the annular groove is L, L==0.2mm-0.3mm.

7. The battery case according to claim 5, characterized in that: The weld is arranged along the annular groove, and part or all of the weld is located on the inner wall of the annular groove.

8. The battery casing according to claim 1, characterized in that: The open end of the bottom shell is provided with a lower pre-installed flange extending outward in a horizontal direction, and the area on the top cover located outside the annular groove constitutes an upper pre-installed flange corresponding to the lower pre-installed flange, and there is a dissipation gap between the upper pre-installed flange and the lower pre-installed flange, and the dissipation gap extends to the outer edge of the weld.

9. A single cell battery, characterized in that: The invention comprises a battery cell and a battery casing as claimed in any one of claims 1 to 8, wherein the battery cell is arranged in the battery casing.

10. A method for producing a single cell, applied to the single cell according to claim 9, comprising the following steps: The battery cell is arranged in the bottom shell, and the top cover is arranged on the opening end of the bottom shell; The sealing surface is brought close to or fitted to the inner wall of the bottom shell and / or the welding reference surface; Welding the top cover and the bottom shell, with the welding path close to or in the annular groove area to form a weld; The excess material of the top cover and the bottom shell outside the weld is trimmed.

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