Welding seam, connecting assembly, battery apparatus, and electric device

Abstract

A welding seam (300), a connecting assembly (600), a battery apparatus (700), and an electric device (800). The welding seam (300) is suitable for being formed by welding a first metal member (120) and a second metal member (200). The first metal member (120) and the second metal member (200) are sequentially arranged in a first direction. The welding seam (300) comprises a plurality of first arc welding seams (310) arranged at intervals in a second direction. The second direction is different from the first direction. The welding seam (300) reduces heat accumulation during welding of the first metal member and the second metal member, and inhibits joint embrittlement, and the plurality of first arc welding seams improve the welding stability of the first metal member and the second metal member.

Description

Welds, connection components, battery devices and electrical equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure is based on and claims the priority of Chinese patent application with application number 202410390111.1 and application date March 29, 2024. The entire content of this Chinese patent application is incorporated herein by reference into this disclosure. Technical Field

[0003] The present application relates to the field of welding technology, and in particular to a welding seam, a connection assembly, a battery device and an electrical equipment. Background Art

[0004] Aluminum alloys are widely used across various industries due to their light weight, low density, and excellent electrical and thermal conductivity. Some electronic products use metal casings such as steel and copper, connected by aluminum alloy tabs. However, welding these steel casings to the aluminum alloy tabs can be prone to heat buildup and joint embrittlement due to the significant differences in the physical and chemical properties of aluminum and steel, leading to unstable welds between the casing and the tabs.

[0005] Summary of the Invention

[0006] The present application provides a welding seam, a connection assembly, a battery device and an electrical equipment to solve the problem of unstable welding between a first metal part and a second metal part.

[0007] To achieve the purpose of this application, this application provides the following technical solutions:

[0008] In the first aspect, the present application provides a weld suitable for being formed by welding a first metal part and a second metal part, wherein the first metal part and the second metal part are arranged sequentially along a first direction, and the weld includes a plurality of first arc welds arranged at intervals along a second direction, and the second direction is different from the first direction.

[0009] In one embodiment, the distance between two adjacent first arc welds in the second direction is the same.

[0010] In one embodiment, the distance between two adjacent first arc welds in the second direction ranges from 0.1 mm to 1 mm.

[0011] In one embodiment, the distance between two adjacent first arc welds in the second direction ranges from 0.1 mm to 0.5 mm.

[0012] In one embodiment, the width of each of the first arc welds in the second direction is 0.05 mm to 0.50 mm.

[0013] In one embodiment, the width of the weld in the second direction is 1 mm to 3 mm.

[0014] In one embodiment, the radius of the plurality of first arc welds is the same, and the radius of each first arc weld is in the range of 15 mm to 20 mm.

[0015] In one embodiment, the center angles of the plurality of first arc welds are the same, and the center angle of each of the first arc welds is in the range of 60° to 90°.

[0016] In one embodiment, a material of one of the first metal member and the second metal member is steel, and a material of the other of the first metal member and the second metal member is aluminum.

[0017] In a second aspect, the present application further provides a connection assembly, comprising a first metal member, a second metal member and the weld as described above, wherein the first metal member and the second metal member are welded to form the weld.

[0018] In one embodiment, the cross-sectional area of ​​the weld in the direction perpendicular to the first direction is 30 mm. 2 ~60mm 2 .

[0019] In a third aspect, the present application also provides a battery device comprising the connection assembly as described in the second aspect, wherein the battery device comprises at least two batteries, the battery comprises a shell, the shell is the first metal part, and the second metal part is electrically connected to two adjacent batteries.

[0020] In one embodiment, the battery further includes a cover plate assembly, and the shell and the cover plate assembly are welded to form a second arc weld;

[0021] The first end of the second metal part is electrically connected to the pole of the cover plate assembly of one of the batteries, and the second end of the second metal part is welded to the shell of the other battery to form the weld. The weld is spaced apart from the second circular arc weld, and the weld is arranged around the circumference of the second circular arc weld.

[0022] In one embodiment, the weld is arranged in an arc shape, the second direction is the radial direction of the weld, and the distance between the first arc weld located at the radial innermost side of the weld and the second arc weld is in the range of 1 mm to 3.5 mm.

[0023] In one embodiment, the second metal member includes a first connecting portion and a second connecting portion connected to each other, the first connecting portion abutting against the terminal post of the cover assembly of one of the batteries, the second connecting portion abutting against the shell of the other battery, and the second connecting portion being located between the outer edge of the shell and the second arc weld;

[0024] The distance between the first arc weld located at the radial innermost side of the weld and the outer edge of the second connecting portion close to the second arc weld in the second direction is in the range of 1 mm to 2.5 mm.

[0025] In one embodiment, the distance between the first arc weld located at the radially outermost side of the weld and the outer edge of the shell in the second direction is in a range of 2 mm to 5 mm.

[0026] In one embodiment, the battery is a cylindrical battery.

[0027] In one embodiment, the cross-sectional area S of the weld perpendicular to the first direction is 30 mm 2 ~60mm 2 , S=b*θ*π*R / 180°,

[0028] b is the width b of the weld in the second direction, and the range of b is 1 mm to 3 mm;

[0029] θ is the center angle of each of the first arc welds, and the range of θ is 60° to 90°;

[0030] R is the radius of each of the first arc welds, and the range of R is 15 mm to 20 mm.

[0031] In a fourth aspect, the present application further provides an electrical device comprising the battery device described in the third aspect.

[0032] The weld, connection assembly, battery device and electrical equipment provided by the present application are formed by welding a first metal part and a second metal part. The first metal part and the second metal part are arranged in sequence along a first direction. The weld includes multiple first arc welds arranged at intervals along a second direction different from the first direction. Each first arc weld is formed separately, which reduces the heat accumulation between the welding of the first metal part and the second metal part, inhibits the embrittlement of the joint, and the multiple first arc welds improve the stability of the welding between the first metal part and the second metal part. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the implementation methods or the description of the prior art. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] FIG1 is a schematic structural diagram of a connecting assembly and a pressing tool according to an embodiment of the present application;

[0035] FIG2 is a schematic structural diagram of a weld according to an embodiment of the present application;

[0036] FIG3 is an enlarged view of a weld according to an embodiment of the present application;

[0037] FIG4 is a schematic structural diagram of a second metal member and a weld according to an embodiment of the present application;

[0038] FIG5 is a cross-sectional view of the welding of a first metal member and a second metal member according to an embodiment of the present application;

[0039] FIG6 is a partial structural diagram of FIG5 ;

[0040] FIG7 is a schematic diagram of some electrical equipment of the present application.

[0041] Explanation of the accompanying drawings: 120, first metal part; 121, steel layer; 122, nickel-plated layer; 130, second arc weld; 200, second metal part; 210, first connecting portion; 220, second connecting portion; 230, bent edge; 300, weld; 310, first arc weld; 400, cover assembly; 410, pole; 420, cover; 500, clamping tool; 510, through hole; 600, connecting assembly; 700, battery device; 800, electrical equipment. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0043] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may be an intermediate component. When a component is referred to as being "connected to" another component, it may be directly connected to the other component or there may be an intermediate component.

[0044] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used in this application includes any and all combinations of one or more of the relevant listed items.

[0045] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0046] Power-consuming devices 800 include electric vehicles, energy storage devices, and communications equipment. These devices are powered by batteries, which drive their operation. Batteries can be categorized as power batteries and reserve batteries. Power batteries are primarily used in electric vehicles and power tools, while reserve batteries are primarily used in emergency backup power supplies, military communications, and other fields.

[0047] The battery assembly consists of multiple connected cells to increase overall capacity, storing more energy at the same voltage while also providing longer-lasting power. By combining multiple cells, the overall battery assembly reduces the frequency of each cell's usage, extending the lifespan of each individual cell. This combined battery assembly allows for faster charging and discharging, providing power to devices faster and allowing for faster full charges.

[0048] During the manufacturing process of battery devices, multiple cells need to be connected into battery packs to provide the required voltage and capacity. There are many ways to connect batteries, and one common method is to weld connectors. Connectors are metal sheets that connect multiple cells in series or parallel to meet the voltage and capacity requirements of different battery packs. Laser welding, resistance welding, and soldering are commonly used to achieve these connections.

[0049] In the existing technology, the battery shell is made of metal materials such as steel and copper, and the connecting plate is made of aluminum alloy. When welding the battery shell and the connecting plate, due to the large differences in the physical and chemical properties of aluminum and steel, problems such as heat accumulation and joint embrittlement are prone to occur during welding, resulting in unstable welding between the shell and the connecting plate.

[0050] Please refer to Figures 1, 2 and 3. The present application provides a connection assembly 600, which includes a first metal member 120 and a second metal member 200. The first metal member 120 and the second metal member 200 are welded to form a weld 300. The weld 300 includes a plurality of first arc welds 310 arranged at intervals.

[0051] The first metal member 120 can be a battery housing or a distribution box lead, and the second metal member 200 can be a connecting piece between batteries or a battery pack's total positive / negative lead. If the first metal member 120 is a battery housing, the second metal member 200 is a connecting piece between batteries; if the first metal member 120 is a distribution box lead, the second metal member 200 is a battery pack's total positive / negative lead.

[0052] The first metal member 120 and the second metal member 200 are arranged sequentially along a first direction X, and a plurality of first circular arc welds 310 are arranged at intervals along a second direction Y. The first direction X is not used in the second direction Y, that is, the first direction X and the second direction Y have an angle greater than zero and less than 180 degrees. The weld 300 provided in the embodiment of the present application includes a plurality of first circular arc welds 310 arranged at intervals along a second direction Y different from the first direction X. Each first circular arc weld 310 is formed separately, thereby reducing heat accumulation during the welding of the first metal member 120 and the second metal member 200, suppressing embrittlement of the joint, and improving the stability of the welding between the first metal member 120 and the second metal member 200.

[0053] In some embodiments, the angle between the first direction X and the second direction Y is 90°, that is, the first direction X is perpendicular to the second direction Y. When the first metal member 120 is a cylindrical battery shell, the first metal member 120 and the second metal member 200 are stacked along the axial direction of the first metal member 120, and the second metal member 200 is connected to one axial end of the first metal member 120. That is, the first direction X is the axial direction of the first metal member 120, and the second direction Y can be the radial direction of the first metal member 120.

[0054] 2 and 3 , the intervals a between two adjacent first arc welds 310 in the second direction Y are the same, so that the overall consistency of the weld 300 is good and the structural strength of the weld 300 is improved.

[0055] The distance a between two adjacent first arc welds 310 in the second direction Y ranges from 0.1 mm to 1 mm. Within this range, if a is less than 0.1 mm, heat accumulation may occur; if a is greater than 1 mm, the welding strength between the first metal part 120 and the second metal part 200 may be reduced.

[0056] In some embodiments, the distance a between two adjacent first arc welds 310 in the second direction Y ranges from 0.1 mm to 0.5 mm, that is, the distance a between two adjacent first arc welds 310 in the second direction Y can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, etc. The distance a between two adjacent first arc welds 310 in the second direction Y can be different along the extension direction of the first arc welds 310.

[0057] It should be noted that the spacing a can be measured relative to the center position of each first arc weld 310 in the second direction Y, or relative to the outer edge of each first arc weld 310 on the same side along the second direction Y. The center position of the first arc weld 310 in the second direction Y can be the end or the middle of the first arc weld 310 in the direction of its extension. The width of each first arc weld 310 in the second direction Y is 0.05 mm to 0.50 mm. The width of the first arc weld 310 in the second direction Y is the dimension between the outer edges of the first arc weld 310 in the second direction Y. If the width of the first arc weld 310 in the second direction Y is less than 0.05 mm, the overall flow area of ​​the weld 300 and the weld strength between the first metal component 120 and the second metal component 200 will be reduced. If the width of the first arc weld 310 in the second direction Y is greater than 0.50 mm, heat accumulation may occur.

[0058] The weld 300, which is composed of multiple first circular arc welds 310, is generally arc-shaped. The width b of the weld 300 in the second direction Y is 1 mm to 3 mm. The number of first circular arc welds 310 can be 2, 3, 4, 6, 10, etc., without specific limitation. In this embodiment of the application, the number of first circular arc welds 310 is 6, and the spacing a between two adjacent first circular arc welds 310 in the second direction Y is 0.4 mm.

[0059] In the present application, the radius of multiple first arc welds 310 is the same, and the center angle of multiple first arc welds 310 is the same, so that the overall consistency of the weld 300 is good; wherein, the radius R of each first arc weld 310 ranges from 15mm to 20mm, and the center angle θ of each first arc weld 310 ranges from 60° to 90°.

[0060] With reference to Figures 1, 2, and 4, in an embodiment of the present application, the first metal part 120 is the shell of the battery, and the material of the battery shell can be steel. The second metal part 200 is a connecting piece connecting multiple batteries, and the material of the connecting piece can be aluminum. The flow area design of the weld 300 between the steel shell cylindrical shell and the connecting piece should meet the flow requirement of 120A-250A. The flow area between the battery shell and the connecting piece is the cross-sectional area S of the weld 300 perpendicular to the first direction X in this application, S=b*θ*π*R / 180°. In some embodiments, the cross-sectional area S of the weld 300 perpendicular to the first direction X is in the range of 30mm 2 ~60mm 2 , while ensuring the welding strength of the battery shell and the connecting piece, to meet the overcurrent requirements between the battery shell and the connecting piece.

[0061] The battery assembly 700 includes multiple batteries, with a second metal member 200 connected to two adjacent batteries. Each battery includes a housing and a cover assembly 400. The housing and cover assembly 400 are welded to form a second arc weld 130. In some embodiments, the cover assembly 400 includes a terminal 410 and a cover 420. The terminal 410 is mounted on the cover 420 and insulated from the cover 420. The cover 420 of the same battery is welded to the housing to form a second arc weld 130. The first end of the second metal member 200 is electrically connected to the terminal 410 of one battery, and the second end of the second metal member 200 is welded to the housing of another battery to form a weld 300, thereby achieving electrical connection between the multiple batteries. The weld 300 is spaced apart from the second arc weld 130 to prevent interference between the welds 300 and 130. The weld 300 is arranged circumferentially around the second arc weld 130 to enhance the weld strength between the second metal member 200 and the housing.

[0062] With reference to Figures 1, 5, and 6, in the embodiment of the present application, the battery shell is made of nickel-plated steel, and the thickness of the battery shell is 0.6 mm. The thickness of 0.6 mm can provide sufficient structural strength to ensure the stability and safety of the battery during use, and is also conducive to improving the heat dissipation performance of the battery. Nickel is plated on the surface of the steel layer 121, and the thickness of the nickel-plated layer 122 ranges from 3um to 6um. The material of the connecting piece is aluminum alloy, and the connecting piece adopts 0.3mm to 0.5mm 1060AL, so that the aluminum connecting piece and the steel shell are stably welded to form a high-strength weld joint. When the battery is welded to the metal connecting piece, the aluminum alloy melts first when heated. When the upper layer of aluminum is completely melted, the lower layer of steel melts. The aluminum content of the molten pool in the initial molten state is relatively high. The nickel-plated layer 122 is set on the steel layer 121. When cooling, the aluminum and nickel first react to precipitate NiAl3, which can effectively reduce the formation of the Fe-Al binary brittle phase in the joint, solving the embrittlement problem of the steel-aluminum dissimilar metal weld joint.

[0063] This application takes the welding of the shell of a steel-shell cylindrical battery and an aluminum metal connecting piece as an example to illustrate. In order to achieve the welding of the aluminum metal connecting piece and the steel shell dissimilar metal, the present invention provides a steel and aluminum dissimilar metal single-mode high-speed arc welding method. The welding method includes the following four steps:

[0064] Step 1: Pre-treat the welding materials. Use alcohol to clean and wipe the metal connector and the shell welding surface before welding.

[0065] Step 2: Install and fix the metal connector. Place the cleaned metal connector on the end of the shell, with the metal connector on top and the steel shell on the bottom. Use the pressing tool 500 to press the area of ​​the metal connector to be welded onto the shell.

[0066] Step 3: Set the laser welding track. Set the laser welding track to the arc welding track. Arc welding is done from top to bottom.

[0067] Step 4: Laser welding: weld the welding area according to the set parameters, use single-mode laser welding with a smaller spot size, use a fast rise and slow fall mode for welding power, and use high-speed welding.

[0068] The welding method of the present application can reduce the oil and impurities on the welding surface of the metal connector and the shell through step one, thereby improving the efficiency of heat conduction and making the welding process more stable and reliable. In step two, the metal connector and the shell are compressed using a clamping tool 500 to reduce the gap between the metal connector and the shell, which can reduce the formation of pores and slag inclusions during welding, thereby improving the welding quality, and a small gap can make the weld joint tighter, reduce gaps and defects, and thus improve the strength of the weld joint; in some embodiments, a through hole 510 for the laser beam to pass through is provided on the clamping tool 500. In step three, by setting the laser welding trajectory, each first arc weld 310 is formed separately, and the direct influence between the multiple first arc welds 310 is small, and the consistency of the weld 300 is easy to control. In step 4, a 20um fiber core diameter single-mode laser is used for welding, with a welding power of 800W-1200W, a welding speed of 1000mm / s-1200mm / s, and a defocus of 0±1mm. A fast rise and slow fall mode is adopted. The aluminum alloy in the arc starting section has a low laser absorption rate, and high power is reached at the initial moment to melt the material. As welding proceeds, the aluminum absorbs more laser light due to heat, and the slow power fall can effectively solve the problem of deep penetration caused by energy accumulation at the arc ending position, ensuring uniform penetration of the entire weld 300.

[0069] In some embodiments, the welding material is 0.4mm 1060Al and 0.6mm nickel-plated steel, and the nickel plating layer 122 is 5um thick; the welding track design overcurrent requirement is 160A for a single connecting piece and welding track, and the single battery shell welding overcurrent area is 40mm 2 ; The actual welding weld 300 has a width of 2 mm, and arc welding is adopted. The radius of the first arc weld 310 is 16 mm, the central angle θ of the first arc weld 310 is 80°, and the spacing between multiple first arc welds 310 is 0.4 mm; the welding power is 1000 W; the welding speed is 1200 mm / s, and the defocus amount is 0 mm. At this time, the welding effect is better, and the welding strength and penetration meet the product requirements.

[0070] In the present application, the connecting piece includes a first connecting portion 210 and a second connecting portion 220 connected to each other, the first connecting portion 210 is abutted against the pole 410 of one of the batteries, and the second connecting portion 220 is abutted against the shell of the other battery, the second connecting portion 220 is located between the outer edge of the shell and the second arc weld 130, and a bent edge 230 is connected between the second connecting portion 220 and the first connecting portion 210, so that there is a height difference between the first connecting portion 210 and the second connecting portion 220, so that only the second connecting portion 220 part of the connecting piece is abutted against the battery shell.

[0071] In one embodiment, the distance L1 between the first arc weld 310 and the second arc weld 130 located at the radial innermost side of the weld 300 is in the range of 1 mm to 3.5 mm. If the distance L1 is less than 1.0 mm, the clamping tool 500 will press onto the outside of the connecting piece, causing the clamping tool 500 to press out the connecting piece, causing the connecting piece to deform and warp, resulting in a poor weld in the weld 300; if the distance L1 is greater than 3.5 mm, the clamping tool 500 will press onto the bent edge 230 of the connecting piece, and the bent edge 230 will interfere with the clamping tool 500, resulting in abnormal clamping of the connecting piece, resulting in a poor weld in the weld 300.

[0072] The distance L2 in the second direction Y between the first arc weld 310 located at the radially innermost side of the weld 300 and the outer edge of the second connecting portion 220 on the side close to the second arc weld 130 is in the range of 1 mm to 2.5 mm. If the distance L2 is less than 1.0 mm, the weld 300 between the connecting piece and the shell will be welded on the second arc weld 130, causing the weld 300 and the second arc weld 130 to overlap, posing a risk of weld penetration. If the distance L2 is greater than 2.5 mm, the clamping fixture 500 will press against the bent edge 230 of the connecting piece, causing the bent edge 230 to interfere with the clamping fixture 500, resulting in abnormal clamping of the connecting piece and a poor weld in the weld 300.

[0073] The distance L3 between the first arc weld 310 located at the radially outermost side of the weld 300 and the outer edge of the shell in the second direction Y ranges from 2 mm to 5 mm. If the distance L3 is less than 2 mm, the clamping tool 500 will press on the outer edge of the shell, causing the connecting piece to deform and warp, and the weld 300 will be a poor weld; if the distance L3 is greater than 5 mm, the weld 300 between the connecting piece and the shell will be welded on top of the second arc weld 130, causing the weld 300 to overlap with the second arc weld 130, and there is a risk of welding through.

[0074] The present application uses an arc welding method, and the welding time of each first arc weld 310 is only 18.6ms, which greatly improves production efficiency and reduces production costs. The welding time of a single first arc weld 310 is short, the residence time of the first arc weld 310 in the liquid state is short, and each first arc weld 310 is welded from top to bottom along the same arrow direction (refer to Figure 2). Each first arc weld 310 is formed separately. After the first metal part 120 and the second metal part 200 are welded, the weld 300 as a whole has a tooth shape, the influence between the welds 300 is small, and the consistency of the weld 300 is relatively easy to control, thereby improving the welding strength and stability of the first metal part 120 and the second metal part 200.

[0075] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", and "outside" are based on the orientation or positional relationship described in the accompanying drawings. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present application.

[0076] The above disclosure is only a preferred embodiment of the present application, and certainly cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present application are still within the scope covered by the present application.

Claims

1. A weld (300), wherein: The invention is suitable for being formed by welding a first metal part (120) and a second metal part (200), wherein the first metal part (120) and the second metal part (200) are arranged in sequence along a first direction, and the weld (300) includes a plurality of first arc welds (310) arranged at intervals along a second direction, and the second direction is different from the first direction.

2. The weld seam (300) according to claim 1, wherein The spacing between two adjacent first arc welds (310) in the second direction is the same.

3. The weld seam (300) according to claim 2, wherein The distance between two adjacent first arc welds (310) in the second direction ranges from 0.1 mm to 1 mm.

4. The weld (300) according to claim 2, wherein The distance between two adjacent first arc welds (310) in the second direction ranges from 0.1 mm to 0.5 mm.

5. The weld (300) according to any one of claims 1 to 4, wherein: The width of each first arc weld (310) in the second direction is 0.05 mm to 0.50 mm.

6. The weld (300) according to any one of claims 1 to 5, wherein: The width of the weld (300) in the second direction is 1 mm to 3 mm.

7. The weld (300) according to any one of claims 1 to 6, wherein: The radius of the plurality of first circular arc welds (310) is the same, and the radius of each first circular arc weld (310) ranges from 15 mm to 20 mm.

8. The weld (300) according to any one of claims 1 to 7, wherein: The center angles of the plurality of first circular arc welds (310) are the same, and the center angle of each first circular arc weld (310) is in the range of 60° to 90°.

9. The weld (300) according to any one of claims 1 to 8, wherein: The material of one of the first metal part (120) and the second metal part (200) is steel, and the material of the other of the first metal part (120) and the second metal part (200) is aluminum.

10. A connection assembly (600), wherein: The invention comprises a first metal part (120), a second metal part (200) and a weld (300) according to any one of claims 1 to 9, wherein the first metal part (120) and the second metal part (200) are welded to form the weld (300).

11. The connection assembly (600) according to claim 10, wherein: The cross-sectional area of ​​the weld (300) perpendicular to the first direction is 30 mm 2 ~60mm 2 .

12. A battery device (700), wherein: The invention comprises a connection assembly (600) as claimed in claim 10 or 11, wherein the battery device (700) comprises at least two batteries, the battery comprises a shell, the shell is the first metal part (120), and the second metal part (200) is electrically connected to two adjacent batteries.

13. The battery device (700) according to claim 12, wherein: The battery further comprises a cover plate assembly (400), and the shell and the cover plate assembly (400) are welded to form a second arc weld (130); The first end of the second metal member (200) is electrically connected to the pole (410) of the cover plate assembly (400) of one of the batteries, and the second end of the second metal member (200) is welded to the shell of the other battery to form the weld (300). The weld (300) and the second circular arc weld (130) are spaced apart, and the weld (300) is arranged around the circumference of the second circular arc weld (130).

14. The battery device (700) according to claim 13, wherein: The weld (300) is arranged in an arc shape, the second direction is the radial direction of the weld (300), and the distance between the first arc weld (310) located at the radial innermost side of the weld (300) and the second arc weld (130) is in the range of 1 mm to 3.5 mm.

15. The battery device (700) according to claim 14, wherein: The second metal member (200) comprises a first connecting portion (210) and a second connecting portion (220) connected to each other, the first connecting portion (210) being held against the pole (410) of the cover plate assembly (400) of one of the batteries, the second connecting portion (220) being held against the shell of the other battery, and the second connecting portion (220) being located between the outer edge of the shell and the second circular arc weld (130); The distance between the first arc weld (310) located radially innermost of the weld (300) and the outer edge of the second connecting portion (220) on the side close to the second arc weld (130) in the second direction ranges from 1 mm to 2.5 mm.

16. The battery device (700) according to claim 15, wherein: The distance between the first arc weld (310) located at the radially outermost side of the weld (300) and the outer edge of the shell in the second direction ranges from 2 mm to 5 mm.

17. The battery device (700) according to any one of claims 12 to 16, wherein: The battery is a cylindrical battery.

18. The battery device (700) according to any one of claims 12 to 17, wherein: The cross-sectional area S of the weld (300) perpendicular to the first direction is 30 mm. 2 ~60mm 2 , S=b*θ*π*R / 180°, b is the width b of the weld (300) in the second direction, and the range of b is 1 mm to 3 mm; θ is the center angle of each of the first arc welds (310), and the range of θ is 60° to 90°; R is the radius of each of the first arc welds (310), and the range of R is 15 mm to 20 mm.

19. An electrical device (800), wherein: Comprising the battery device according to any one of claims 12 to 18.

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