Battery cell and manufacturing method therefor, battery, and electrical device

Abstract

The present application discloses a battery cell and a manufacturing method therefor, a battery, and an electrical device. The battery cell comprises a packaging bag, an electrode assembly, a tab and an adapter. The tab comprises a plurality of tab units; each tab units has one end connected to the electrode assembly, and the other ends of the tab units are gathered to form a connecting part; the connecting part comprises a first connecting section, a bent section and a second connecting section; the bent section is connected to the first connecting section and the second connecting section; the first connecting section and the second connecting section are spaced apart from each other; and the second connecting section is located on the side of the first connecting section away from the electrode assembly. The adapter is soldered and connected to the side of the second connecting section away from the first connecting section, to form a soldering part, and in a second direction, the length w of the soldering part is larger than or equal to 0.3 mm and smaller than or equal to 5 mm, the second direction being the direction of extension of the second connecting section, the first direction being the length direction of the electrode assembly, and the second direction being perpendicular to the first direction. The present application mitigates the problems of short soldering life and low soldering strength, and can reduce the thickness of the battery cell and increase the energy density.

Description

Battery cell and manufacturing method thereof, battery and electrical equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 30, 2024, with application number 202410383381.X and entitled “Battery Cell and Method for Manufacturing Same, Battery and Electrical Equipment”. Technical Field

[0002] The present application relates to the field of energy storage technology, and in particular to a battery cell and a manufacturing method thereof, a battery, and an electrical device. Background Art

[0003] Battery cells are widely used in electronic devices, such as foldable screen mobile phones. The thinner the electronic device, the thinner the thickness requirement of the battery cells. At present, reducing the thickness of the battery cells and increasing the energy density of the battery cells have become the research and development direction in the battery cell field. Summary of the Invention

[0004] In view of this, it is necessary to provide a battery cell and a manufacturing method thereof, a battery and an electrical device, which can reduce the thickness of the battery cell and improve the energy density of the battery cell.

[0005] An embodiment of the present application provides a battery cell, comprising: a packaging bag, an electrode assembly, a tab and an adapter. The electrode assembly is provided in the packaging bag. The tab comprises a plurality of tab units, one end of the plurality of tab units is connected to the electrode assembly, and the other end is gathered to form a connecting portion, the connecting portion comprising a first connecting segment, a bending segment and a second connecting segment, the bending segment connecting the first connecting segment and the second connecting segment, the first connecting segment and the second connecting segment are arranged along a first direction, and the second connecting segment is located on the side of the first connecting segment away from the electrode assembly. The adapter is welded to connect the side of the second connecting segment away from the first connecting segment and form a welding portion, and along the second direction, the length w of the welding portion satisfies 0.3mm≤w≤5mm, the second direction is the extension direction of the second connecting segment, the first direction is the length direction of the electrode assembly, and the second direction is perpendicular to the first direction.

[0006] The present application uses an adapter to weld the second connecting section to the side facing away from the first connecting section, so that the welding portion can be cut to length as needed, which facilitates setting the length w of the welding portion along the second direction to 0.3mm≤w≤5mm. If the length w of the welding portion along the second direction is less than 0.3mm, the welding size will be small, the welding strength between the adapter and the second connecting section will be low, the life of the welding portion will be short, the connection between the adapter and the second connecting section will be unstable, and in the process of forming the bending section, the tab unit will be prone to damage and breakage. If the length w of the welding portion along the second direction is greater than 5mm, the welding portion will easily exceed the thickness of the battery cell, there is a risk of puncturing the packaging bag, and it is not conducive to reducing the thickness of the battery cell. The present application increases the size of the welding portion by setting the length w of the welding portion to 0.3mm≤w≤5mm, reduces the problems of low welding life and low welding strength, facilitates bending the connecting portion, and is beneficial to reducing the thickness of the battery cell and improving energy density.

[0007] In one or more of the above optional embodiments, 0.3 mm ≤ w ≤ 2.5 mm, which can further reduce the thickness of the battery cell and further improve the energy density.

[0008] In one or more of the above optional embodiments, the weld portion includes a weld print, which may be circular or arcuate. Along a first direction, the diameter d of the circle corresponding to the weld print satisfies d ≥ 0.5 mm. In a second direction perpendicular to the first direction, increasing the size of the weld print can increase weld strength and weld head life. The present application utilizes an adapter to weld the side of the second connecting segment facing away from the first connecting segment, allowing the weld portion to be cut to length as needed. This allows the corresponding weld print to be made larger, improving weld strength and weld head life. In contrast, the weld portion in the prior art cannot be cut, making it difficult to enlarge the weld print.

[0009] In one or more of the above optional embodiments, d≥0.75 mm, further improving welding strength and welding head life.

[0010] In one or more optional embodiments above, the adapter includes a first section and a second section, the first section is welded to the second connecting section, and the second section is connected to the first section and extends out of the packaging bag.

[0011] In one or more of the above optional embodiments, along the first direction, the projection of the connecting portion is located within the projection of the electrode assembly, thereby reducing the space occupied by the connecting portion and lowering the risk of the connecting portion piercing the packaging bag. The projection of the welding portion is located within the projection of the electrode assembly, thereby reducing the space occupied by the welding portion, facilitating a reduction in the thickness of the battery cell and reducing the risk of the welding portion piercing the packaging bag.

[0012] In one or more of the above optional embodiments, along the first direction, the projection of the first section is located within the projection of the connecting portion, which reduces the space occupied by the first section and is conducive to reducing the thickness of the battery cell.

[0013] In one or more optional embodiments above, the thickness h1 of the adapter is 0.001 mm ≤ h1 ≤ 1 mm, which is beneficial for welding the first section and the second connecting section and reduces the space occupied by the adapter.

[0014] In one or more of the above optional embodiments, insulating glue is also included. Along the thickness direction of the second section, the insulating glue is arranged on both sides of the second section. The insulating glue connects the packaging bag, which can insulate the packaging bag and the adapter, thereby reducing the risk of short circuit between the adapter and the metal layer in the packaging bag.

[0015] In one or more of the above optional embodiments, an insulating member is further included, connected to a side of the insulating adhesive facing away from the second section. The insulating member connects the electrode assembly and covers the connecting portion, the welding portion, and a portion of the transition piece, providing insulation protection for the connecting portion, the welding portion, and a portion of the transition piece, thereby reducing the risk of any of the connecting portion, the welding portion, or the portion of the transition piece contacting the packaging bag and causing a short circuit.

[0016] In one or more of the above optional embodiments, the material of the insulating glue includes at least one of polypropylene and polyethylene.

[0017] In one or more optional embodiments above, the insulating member includes a base layer and an adhesive layer connected to the base layer, the material of the base layer includes polyimide, and the material of the adhesive layer includes modified polypropylene.

[0018] In one or more of the above optional embodiments, there is a first space between the first connecting segment and the second connecting segment, and the first space is provided with an insulating filler, which can support the first connecting segment and the second connecting segment to reduce the risk of the welding part being inserted into the electrode assembly.

[0019] In one or more of the above optional embodiments, the thickness H of the battery cell is 2.5 mm to 5.5 mm.

[0020] An embodiment of the present application further provides a battery, comprising the battery cell in any of the above embodiments.

[0021] An embodiment of the present application further provides an electrical device, comprising the battery in any of the above embodiments.

[0022] One embodiment of the present application further provides a method for manufacturing the aforementioned battery cell, comprising the following steps: gathering a plurality of tab units to form a connecting portion; welding an adapter to a side of the second connecting segment facing away from the first connecting segment to form a weld; trimming the weld; and bending the connecting portion so that the weld is disposed along the thickness of the battery cell.

[0023] The manufacturing method of the present application welds the adapter to the side of the second connecting section facing away from the first connecting section, which is convenient for cutting the welding part. By welding first and then cutting, the welding size of the first section and the second connecting section is increased before cutting, which can improve the positioning accuracy of the first section and the connecting part, facilitate welding, improve welding strength and life, reduce problems such as cold welding and weld breakage, and cut after welding so that the welding size meets the process requirements, reducing the risk of the tab unit breaking during the bending of the connecting part, which is beneficial to controlling the size of the welding part and the thickness of the battery cell.

[0024] The above-mentioned battery cells, batteries and electrical equipment, by welding the adapter to connect the second connecting section to the side facing away from the first connecting section, enable the welding portion to be cut to length as required, and set the length w of the welding portion to 0.3mm≤w≤5mm, thereby increasing the size of the welding portion, reducing the problems of low welding life and low welding strength, facilitating the bending of the connecting portion, and helping to reduce the thickness of the battery cell and improve the energy density. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is a schematic structural diagram of a battery cell in some embodiments.

[0026] FIG2 is a schematic cross-sectional view of a battery cell in some embodiments.

[0027] FIG3 is a schematic cross-sectional view of a battery cell in another state in some embodiments.

[0028] FIG4 is a schematic cross-sectional view of a battery cell in another state in some embodiments.

[0029] FIG5 is a schematic diagram showing the structure of a weld print in some embodiments.

[0030] FIG6 shows a schematic structural diagram of welding marks in other embodiments.

[0031] FIG. 7 is a schematic structural diagram of an insulating member in some embodiments.

[0032] FIG8 is a schematic flow chart showing a method for manufacturing a battery cell in some embodiments.

[0033] FIG9 is a schematic structural diagram of a battery and an electrical device in some embodiments.

[0034] Description of the main components: Battery cell 100 Packaging bag 10 Main body 11 Sealing part 12 First sealing part 121 Electrode assembly 20 First pole piece 21 First current collector 211 First active material layer 212 Separator 22 Second pole piece 23 Second current collector 231 Tab 30 Tab unit 31 Connecting part 30a First connecting section 301 Second connecting section 302 Bend section 303 First space 304 Adapter 40 Welding part 41 Welding mark 410 First section 42 Second section 43 Insulating adhesive 50 Insulating member 60 Base layer 61 Adhesive layer 62 Battery 200 Electrical device 300 First directionX Second direction Y Third direction Z

[0035] The following specific embodiments will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0036] The following detailed description is illustrative and non-limiting. It is intended to provide a basic understanding of the present application and is not intended to identify the key or decisive elements of the present application or to limit the scope of protection. As long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any manner.

[0037] When a component is referred to as being “disposed on” another component, it can be directly disposed on the other component or there may be a component intervening therebetween. When a component is referred to as being “connected to” another component, it can be directly connected to the other component or there may be a component intervening therebetween.

[0038] It can be understood that the term "perpendicular" is used to describe the ideal state between two components. In actual production or use, there may be a state between the two components that is approximately perpendicular or equal. For example, combined with numerical descriptions, perpendicular can refer to the angle between two straight lines being in the range of 90°±10°, perpendicular can also refer to the dihedral angle between two planes being in the range of 90°±10°, and perpendicular can also refer to the angle between a straight line and a plane being in the range of 90°±10°. The two components described as "perpendicular" may not be absolute straight lines or planes, but may be roughly straight lines or planes. From a macroscopic perspective, a component can be considered a "straight line" or a "plane" if the overall extension direction is a straight line or a plane.

[0039] Unless otherwise defined, the term "plurality" herein, when used to describe the number of components, specifically means that the components are two or more.

[0040] 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 of the embodiments may be combined with each other.

[0041] Referring to FIG. 1 and FIG. 2 , an embodiment of the present application provides a battery cell 100 , including a packaging bag 10 and an electrode assembly 20 . The electrode assembly 20 is disposed in the packaging bag 10 .

[0042] In some embodiments, the battery cell 100 includes a tab 30, which includes multiple tab units 31. One end of the multiple tab units 31 is connected to the electrode assembly 20, and the other end is gathered to form a connecting portion 30a. The connecting portion 30a includes a first connecting segment 301, a second connecting segment 302, and a bent segment 303. The bent segment 303 connects the first connecting segment 301 and the second connecting segment 302. The first connecting segment 301 and the second connecting segment 302 are arranged along a first direction Y, and the second connecting segment 302 is located on the side of the first connecting segment 301 facing away from the electrode assembly 20. The gathering refers to the compression and interconnection of the multiple tab units 31 along the thickness direction to facilitate connection to external electrical connectors.

[0043] In some embodiments, the battery cell 100 includes an adapter 40, which is welded to a side of the second connecting segment 302 facing away from the first connecting segment 301 to form a weld portion 41. A length w of the weld portion 41 along a second direction X, where the second connecting segment 302 extends, satisfies the condition 0.3 mm ≤ w ≤ 5 mm.

[0044] In this application, the adapter 40 is welded to the side of the second connecting section 302 facing away from the first connecting section 301, which facilitates setting the length w of the weld portion 41 along the second direction X to 0.3mm≤w≤5mm. If the length w of the weld portion 41 along the second direction X is less than 0.3mm, the weld size is small, the weld strength between the adapter 40 and the second connecting section 302 is low, the life of the weld portion 41 is shortened, and the connection between the adapter 40 and the second connecting section 302 is unstable. During the formation of the bent section 303, the tab unit 31 is prone to damage or breakage. If the length w of the weld portion 41 along the second direction X is greater than 5mm, the weld portion 41 is likely to extend beyond the thickness of the battery cell 100, posing a risk of puncturing the packaging bag 10 and hindering the reduction of the thickness of the battery cell 100. The present application increases the size of the welding portion 41 by setting the length w of the welding portion 41 to 0.3mm≤w≤5mm, reduces the problems of low welding life and low welding strength, facilitates bending the connecting portion 30a, and is beneficial to reducing the thickness of the battery cell 100 and improving the energy density.

[0045] Alternatively, w can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm , any one of 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4.0mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, and 5.0mm.

[0046] In some embodiments, 0.3 mm ≤ w ≤ 2.5 mm, which can further reduce the thickness of the battery cell 100 and further improve the energy density.

[0047] In some embodiments, the adapter 40 and the second connecting section 302 are ultrasonically welded to form the weld 41. In other embodiments, the adapter 40 and the second connecting section 302 are laser welded, riveted, roller welded, resistance welded, or a combination of laser and ultrasonic welding to form the weld 41.

[0048] In some embodiments, a plurality of tab units 31 are welded together to form the second connection segment 302 .

[0049] Please refer to Figures 5 and 6. In some embodiments, the welding portion 41 includes a weld mark 410, and the shape of the weld mark 410 includes a circle or an arc. The arc refers to a figure formed by an arc and its corresponding chord. Along the first direction X, the diameter d of the circle corresponding to the weld mark 410 satisfies d ≥ 0.5 mm. Increasing the size of the weld mark 410 can improve the welding strength and the life of the welding head. In this application, the side of the second connecting section 302 facing away from the first connecting section 301 is welded and connected by the adapter 40, so that the welding portion 41 can be cut to length as required, so that the corresponding weld mark 410 can be made larger, thereby improving the welding strength and the life of the welding head. However, the welding portion 41 in the prior art cannot be cut, so it is difficult to make the weld mark 410 larger.

[0050] In some embodiments, the solder marks 410 are arranged along the second direction Y.

[0051] In some embodiments, the welding head first forms a circular weld mark 410 , and then cuts the weld portion 41 according to the length requirement of the weld portion 41 . The cut weld mark 410 is arched, circular, or circular plus arched.

[0052] In some embodiments, d≥0.75 mm, further increasing the size of the weld mark 410 and further improving the weld strength and weld head life.

[0053] Referring to FIG. 1 , in some embodiments, a packaging bag 10 includes a main body 11 and a sealing portion 12 . The electrode assembly 20 is disposed in the main body 11 , and the sealing portion 12 is connected to the main body 11 .

[0054] In some embodiments, the sealing portion 12 includes a first sealing portion 121 , and the adapter 40 extends from the first sealing portion 121 .

[0055] In some embodiments, the sealing portion 12 includes two first sealing portions 121 and two adapters 40, the two first sealing portions 121 are arranged along a first direction Y, one adapter 40 extends from one first sealing portion 121 along the first direction Y, and the other adapter 40 extends from the other first sealing portion 121 along a direction opposite to the first direction Y.

[0056] In some embodiments, one of the transition components 40 is made of aluminum, and the other transition component 40 is made of pure nickel or nickel-plated copper.

[0057] In some embodiments, the electrode assembly 20 includes a first electrode piece 21, a separator 22, and a second electrode piece 23. The separator 22 is disposed between the first electrode piece 21 and the second electrode piece 23. The first electrode piece 21 and the second electrode piece 23 have different polarities.

[0058] Optionally, the first pole piece 21 , the isolation film 22 and the second pole piece 23 are stacked in sequence.

[0059] Optionally, the first pole piece 21 , the isolation film 22 and the second pole piece 23 are wound together.

[0060] In some embodiments, the first electrode 21 includes a first current collector 211 and a first active material layer 212 disposed on the first current collector 211 .

[0061] Optionally, the tab unit 31 is welded to an empty foil area of ​​the first current collector 211 where the first active material layer 212 is not provided.

[0062] Optionally, the empty foil area of ​​the first current collector 211 where the first active material layer 212 is not provided can be directly used as the tab unit 31 .

[0063] In some embodiments, the second electrode sheet 23 includes a second current collector 231 and a second active material layer 232 disposed on the second current collector 231 .

[0064] Optionally, the tab unit 31 is welded to an empty foil area of ​​the second current collector 231 where the second active material layer 232 is not provided.

[0065] Optionally, the empty foil area of ​​the second current collector 231 where the second active material layer 232 is not provided can be directly used as the tab unit 31 .

[0066] 2 and 3 , in some embodiments, the adapter 40 includes a first section 42 and a second section 43 . The first section 42 is welded to the second connecting section 302 . The second section 43 is connected to the first section 42 . The second section 43 extends from the first sealing portion 121 to the packaging bag 10 .

[0067] In some embodiments, along the first direction Y, the projection of the connecting portion 30 a is located within the projection of the electrode assembly 20 , which reduces the space occupied by the connecting portion 30 a and lowers the risk of the connecting portion 30 a piercing the packaging bag 10 .

[0068] In some embodiments, along the first direction Y, the projection of the welding portion 41 is located within the projection of the electrode assembly 20 , reducing the space occupied by the welding portion 41 , which is beneficial to reducing the thickness of the battery cell 100 and reducing the risk of the welding portion 41 piercing the packaging bag 10 .

[0069] In some embodiments, along the first direction Y, the projection of the first section 42 is located within the projection of the connecting portion 30 a , which reduces the space occupied by the first section 42 and helps reduce the thickness of the battery cell 100 .

[0070] In some embodiments, the thickness h1 of the adapter 40 satisfies 0.001 mm ≤ h1 ≤ 1 mm. If h1 is less than 0.001 mm, the first section 42 and the second connecting section 302 may easily break during welding. If h1 is greater than 1 mm, the space occupied by the first section 42 in the second direction X and the first direction Y is increased. In the present application, h1 is set to 0.001 mm ≤ h1 ≤ 1 mm, which facilitates welding between the first section 42 and the second connecting section 302 and reduces the space occupied by the adapter 40.

[0071] Optionally, h1 can be any one of 0.001mm, 0.002mm, 0.003mm, ..., 0.997mm, 0.998mm, 0.999mm, and 1mm.

[0072] In some embodiments, the width h2 of the adapter 40 is 1 mm ≤ h2 ≤ 100 mm, which is beneficial for increasing the welding area between the first section 42 and the second connecting section 302 , thereby improving welding strength and welding life.

[0073] Optionally, h2 can be any one of 1mm, 2mm, 3mm...97mm, 98mm, 99mm, 100mm.

[0074] Referring to Figures 1 and 2 , in some embodiments, the battery cell 100 includes insulating adhesive 50 disposed on both sides of the second section 43 along the thickness direction of the second section 43. The insulating adhesive 50 connects to the packaging bag 10, insulating the packaging bag 10 from the adapter 40 and reducing the risk of short circuits between the adapter 40 and the metal layer within the packaging bag 10.

[0075] In some embodiments, the thickness h3 of the insulating adhesive 50 satisfies 0.1mm≤h3≤3mm. If h3 is less than 0.1mm, the bonding strength between the adapter 40 and the packaging bag 10 is low, and a gap is likely to form between the adapter 40 and the packaging bag 10, causing leakage in the packaging bag 10. If h3 is greater than 3mm, the space occupied by the battery cell 100 in the thickness direction is increased. In this application, h3 is set to 0.1mm≤h3≤3mm, which can increase the bonding strength between the adapter 40 and the packaging bag 10 and reduce the space occupied by the insulating adhesive 50 in the thickness direction of the battery cell 100.

[0076] Optionally, h3 can be any one of 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, and 3.0mm.

[0077] In some embodiments, the width of the insulating adhesive 50 is greater than the width of the adapter 40 .

[0078] In some embodiments, the width h4 of the insulating adhesive 50 satisfies 2.0 mm ≤ h4 ≤ 100 mm, which is beneficial for increasing the bonding area between the second section 43 and the packaging bag 10 , improving the bonding strength between the second section 43 and the packaging bag 10 , and reducing the risk of leakage of the packaging bag 10 .

[0079] Optionally, h4 can be any one of 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm...95mm, 96mm, 97mm, 98mm, 99mm, and 100mm.

[0080] In some embodiments, the material of the insulating adhesive 50 includes at least one of polypropylene and polyethylene.

[0081] Please refer to Figures 2 and 7. In some embodiments, the battery cell 100 includes an insulating member 60, which is connected to the side of the insulating glue 50 facing away from the second section 43. The insulating member 60 is connected to the electrode assembly 20. The insulating member 60 covers the connecting portion 30a, the welding portion 41 and a portion of the adapter 40 to provide insulation protection for the connecting portion 30a, the welding portion 41 and a portion of the adapter 40, thereby reducing the risk of any one of the connecting portion 30a, the welding portion 41 and a portion of the adapter 40 contacting the packaging bag 10 and causing a short circuit.

[0082] In some embodiments, the insulating member 60 includes a base layer 61 and an adhesive layer 62 , and the adhesive layer 62 is connected to the base layer 61 .

[0083] In some embodiments, the material of the adhesive layer 62 includes modified polypropylene.

[0084] In some embodiments, the thickness d of the insulating member 60 satisfies 1 μm ≤ d ≤ 1000 μm. If d is less than 1 μm, the bonding strength between the insulating member 60 and the electrode assembly 20 and the insulating adhesive 50 is low. If d is greater than 1000 μm, the space occupied by the battery cell 100 in the thickness direction is increased. The present application sets d to 1 μm ≤ d ≤ 1000 μm, which can increase the bonding strength between the insulating member 60 and the electrode assembly 20 and the bonding strength between the insulating member 60 and the insulating adhesive 50, and reduce the space occupied by the insulating member 60 in the thickness direction of the battery cell 100.

[0085] Optionally, d may be any one of 1 μm, 2 μm, 3 μm, ..., 997 μm, 998 μm, 999 μm, and 1000 μm.

[0086] In some embodiments, the battery cell 100 includes an insulating filler (not shown), defining a first space 304 between the first connecting segment 301 and the second connecting segment 302. The insulating filler is disposed in the first space 304 to support the first connecting segment 301 and the second connecting segment 302, thereby reducing the risk of the weld 41 being inserted upside down into the electrode assembly 20.

[0087] In some embodiments, the thickness H of the battery cell 100 is 2.5 mm to 5.5 mm.

[0088] Optionally, the thickness H of the battery cell 100 is any one of 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 4.0 mm, 4.1 mm, 4.2 mm, 4.3 mm, 4.4 mm, 4.5 mm, 4.6 mm, 4.7 mm, 4.8 mm, 4.9 mm, 5.0 mm, 5.1 mm, 5.2 mm, 5.3 mm, 5.4 mm, and 5.5 mm.

[0089] Referring to FIG. 8 , an embodiment of the present application further provides a method for manufacturing the battery cell 100 , comprising the following steps:

[0090] Step 1: gather the plurality of tab units 31 to form a connecting portion 30a;

[0091] Step 2: Weld the adapter 40 to the side of the second connecting section 302 facing away from the first connecting section 301 to form a welding portion 41;

[0092] Step 3, cutting the welding portion 41;

[0093] Step 4: bend the connecting portion 30 a so that the welding portion 41 is disposed along the thickness direction of the battery cell 100 .

[0094] In some embodiments, the above step 1 specifically includes: gathering the plurality of tab units 31 from top to bottom or from bottom to top or from top to bottom to the middle along the thickness direction of the battery cell 100 , and welding them to form the connecting portion 30 a .

[0095] Referring to FIG. 3 , in some embodiments, step 2 specifically includes positioning the adapter 40 and the second connecting section 302 on a side facing away from the first connecting section 301 , and forming a welding portion 41 by ultrasonic welding.

[0096] Please refer to FIG. 4 . In some embodiments, the step 3 specifically includes: cutting the first section 42 and the second connecting section 302 that are welded together.

[0097] Referring to FIG. 2 , in some embodiments, step 3 specifically includes: bending the connecting portion 30 a to form a bent section 33 , and disposing the welding portion 41 along the thickness direction of the battery cell 100 .

[0098] Please refer to FIG. 2 . In some embodiments, the manufacturing method further comprises: pasting an insulating member 60 so that the insulating member 60 covers the connecting portion 30 a , the welding portion 41 and a portion of the adapter 40 .

[0099] The thinner the battery cell 100 is, the smaller the size of the welding portion 41 needs to be. When the size of the welding portion 41 is reduced, the positioning accuracy of the first section 42 and the connecting portion 30a is low, and problems such as cold welding and weld breakage are likely to occur. The size of the welding portion 41 cannot be guaranteed, the welding strength is low, and the welding life is short. This indirectly leads to the problem that the tab unit 31 is prone to breakage during the bending process of the connecting portion 30a. The height after bending exceeds the thickness of the battery cell 100, which is easy to pierce the packaging bag 10. The battery cell 100 may be at risk of thermal runaway.

[0100] The manufacturing method of the present application welds the adapter 40 and the second connecting section 302 on the side facing away from the first connecting section 301, which is convenient for cutting the welding portion 41. By welding first and then cutting, the welding size of the first section 42 and the second connecting section 302 is increased before cutting, which can improve the positioning accuracy of the first section 42 and the connecting portion 30a, facilitate welding, improve welding strength and life, and reduce problems such as cold welding and weld breakage. Cutting is performed after welding to make the welding size meet the process requirements, reduce the risk of breakage of the tab unit 31 during the bending of the connecting portion 30a, and help control the size of the welding portion 41 and the thickness of the battery cell 100.

[0101] The battery cell 100 of the present application will be further described below through specific embodiments.

[0102] A plurality of battery cells 100 are obtained by the above method. The plurality of battery cells 100 have the same length (114 mm), width (42 mm) and electrode assemblies 20 of the same specifications.

[0103] The battery cell 100 was subjected to a weld strength test. The welding strength test method includes: taking a welded sample, securing the remaining portion of the connecting portion 30a and the second section 43 to a tensile testing machine. After ensuring that the sample is vertical and not skewed, the tensile testing machine is reset and measurement is started. The change in tension during the complete separation of the second connecting section 302 from the first section 42 is recorded. A higher tension value indicates a higher weld strength. The tension during the separation of the second connecting section 302 from the first section 42 varies within a range. In this application, the maximum tension during the separation of the second connecting section 302 from the first section 42 is used.

[0104] Table 1

[0105] According to Examples 1 to 5 and Comparative Examples 1 and 2 in Table 1, it can be seen that the longer the length w of weld portion 41, the larger the weld mark size and the greater the weld strength. When the length of weld portion 41 is 0.2 mm (less than 0.3 mm), the weld strength is low (the maximum tensile force in Table 1 refers to the maximum tensile force of the entire weld). When the length of weld portion 41 is 6 mm (greater than 5 mm), the weld strength is high, but the battery cell thickness is large, which is not conducive to reducing the thickness of the battery cell. In addition, the energy density of the battery cell in Comparative Example 2 is lower than that in Examples 1 to 5 and Comparative Example 1.

[0106] The weld strength between the second connecting segment 302 and the first segment 42 is affected not only by the size of the weld mark 410 but also by the materials of the second connecting segment 302 and the first segment 42. As can be seen from Examples 4 and 5 and Comparative Example 2, when the tensile force applied to the second connecting segment 302 and the first segment 42 exceeds the material limit, the tensile force no longer increases.

[0107] The welding head life test method includes: placing the welding head directly under the VR300 or other 3D measuring equipment, with the welding teeth perpendicular to the lens, and measuring the height of the welding teeth. If the height of the welding teeth is less than 50% of the original height, it is determined that the welding head life limit has been reached.

[0108] Table 2

[0109] As can be seen from Table 2, the larger the diameter d of the circle corresponding to weld mark 410, the larger the weld mark area, and the higher the weld strength (the maximum tensile force in Table 2 refers to the maximum tensile force of a single weld mark). The larger the weld mark area, the larger the welding head used, which is beneficial to improving the life of the welding head. To meet the requirements of welding strength and improving the life of the welding head, the diameter d of the circle corresponding to weld mark 410 is set to d ≥ 0.5 mm in this application.

[0110] Please refer to FIG. 9 , the present application also provides a battery 200 using the above-mentioned battery cell 100 .

[0111] 9 , the present application also provides an electrical device 300 using the battery 200. In one embodiment, the electrical device 300 of the present application may be, but is not limited to, electronic equipment, drones, backup power supplies, electric vehicles, electric motorcycles, electric power-assisted bicycles, power tools, large household battery modules, and the like.

[0112] Those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments fall within the scope disclosed in the present application.

Claims

1. A battery cell, characterized in that: include: packaging bags; an electrode assembly, disposed in the packaging bag; a tab, comprising a plurality of tab units, one end of each of the plurality of tab units being connected to the electrode assembly, and the other end being gathered to form a connecting portion, the connecting portion comprising a first connecting segment, a bent segment, and a second connecting segment, the bent segment connecting the first connecting segment and the second connecting segment, the first connecting segment and the second connecting segment being arranged along a first direction, and the second connecting segment being located on a side of the first connecting segment facing away from the electrode assembly; The adapter is welded to connect the second connecting segment to the side facing away from the first connecting segment to form a welding portion. Along the second direction, the length w of the welding portion satisfies 0.3mm≤w≤5mm. The second direction is the extension direction of the second connecting segment, the first direction is the length direction of the electrode assembly, and the second direction is perpendicular to the first direction.

2. The battery cell according to claim 1, wherein: 0.3mm≤w≤2.5mm.

3. The battery cell according to claim 1, wherein: The welding portion includes a welding mark, and the shape of the welding mark includes a circle or an arcuate shape. The diameter d of the circle corresponding to the welding mark satisfies d≥0.5mm.

4. The battery cell according to claim 3, wherein: d≥0.75mm.

5. The battery cell according to any one of claims 1 to 4, characterized in that: The adapter includes a first section and a second section, the first section is welded to the second connecting section, and the second section is connected to the first section and extends out of the packaging bag.

6. The battery cell according to any one of claims 1 to 4, characterized in that: Along the first direction, a projection of the connecting portion is located within a projection of the electrode assembly, and a projection of the welding portion is located within a projection of the electrode assembly.

7. The battery cell according to claim 5, characterized in that Along the first direction, a projection of the first section is located within a projection of the connecting portion.

8. The battery cell according to any one of claims 1 to 4, characterized in that: The thickness h1 of the adapter is 0.001 mm ≤ h1 ≤ 1 mm.

9. The battery cell according to claim 5, wherein: It also includes insulating glue, which is arranged on both sides of the second section along the thickness direction of the second section, and the insulating glue is connected to the packaging bag.

10. The battery cell according to claim 9, wherein: It also includes an insulating member, which is connected to the side of the insulating glue facing away from the second section, the insulating member is connected to the electrode assembly, and the insulating member covers the connecting part, the welding part and part of the adapter.

11. The battery cell according to claim 9, wherein: The insulating adhesive is made of at least one of polypropylene and polyethylene.

12. The battery cell according to claim 10, wherein: The insulating member includes a base layer and an adhesive layer connected to the base layer. The material of the base layer includes polyimide, and the material of the adhesive layer includes modified polypropylene.

13. The battery cell according to any one of claims 1 to 4, characterized in that: A first space is defined between the first connecting section and the second connecting section, and an insulating filler is provided in the first space.

14. The battery cell according to claim 1, wherein: The thickness H of the battery core is 2.5 mm to 5.5 mm.

15. A battery, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 14.

16. An electrical device, characterized in that: Comprising the battery of claim 15.

17. A method for manufacturing a battery cell according to any one of claims 1 to 14, characterized in that: The following steps are involved: Step 1, gathering the plurality of tab units to form the connecting portion; Step 2: welding the adapter to a side of the second connecting section facing away from the first connecting section to form the welding portion; Step 3, cutting the welding portion; Step 4: bend the connecting portion so that the welding portion is arranged along the thickness direction of the battery cell.

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