Battery cell, battery, electric device, welding device and welding method

Abstract

The present invention relates to the field of battery technology and discloses a battery cell, a battery, an electrical device, a welding device and a welding method. The battery cell includes a shell, a pole and an electrode assembly. The electrode assembly is accommodated in the shell and includes a pole ear portion. The pole ear portion includes a plurality of pole ear sheets, and the plurality of pole ear sheets are stacked and connected to form a gathered portion. A connection portion is formed at a position of the gathered portion for electrical connection with the pole. The gathered portion includes a first region and a second region adjacent to each other. The compaction degree of the plurality of pole ear sheets in the second region is greater than the compaction degree of the plurality of pole ear sheets in the first region. The thickness of the plurality of pole ear sheets in the first region is less than the stacking thickness of the plurality of pole ear sheets in the pole ear portion. At least most of the connection portion falls in the second region. Thus, it is beneficial to improve the connection strength, conductivity reliability and current carrying capacity between the connection portion and the pole, thereby improving the reliability of the battery cell.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery cell, a battery, an electrical device, a welding device and a welding method. Background Art

[0002] In recent years, new energy vehicles have developed by leaps and bounds. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. Among them, the power battery includes a number of battery cells, and the electrode assembly of the battery cell is electrically connected to the pole to realize the charging and discharging of the battery cell. The connection between the electrode assembly and the pole will affect the reliability of the battery cell, so that the reliability of the battery cell needs to be improved. Summary of the invention

[0003] The embodiments of the present invention provide a battery cell, a battery, an electrical device, a welding device and a welding method, which can improve the reliability of the battery cell.

[0004] In a first aspect, an embodiment of the present invention provides a battery cell, comprising: a shell; a pole, which is arranged in the shell; an electrode assembly, which is accommodated in the shell and includes a pole ear portion, the pole ear portion includes a plurality of pole ear sheets, the plurality of pole ear sheets are stacked and connected to form a gathered portion, and a connecting portion is formed at a position of the gathered portion for electrical connection with the pole; wherein the gathered portion includes a first area and a second area adjacent to each other, the degree of compaction of the plurality of pole ear sheets in the second area is greater than the degree of compaction in the first area, the thickness of the plurality of pole ear sheets in the first area is less than the stacking thickness of the plurality of pole ear sheets in the pole ear portion, at least most of the connecting portion falls in the second area, a plurality of first welding grooves arranged at intervals are formed in the first area, a plurality of second welding grooves arranged at intervals are formed in the second area, and the depth of the second welding groove is less than the depth of the first welding groove.

[0005] In the above technical solution, since at least most of the connecting part falls within the second area, and the degree of compaction of the multiple pole tabs in the second area is greater than that in the first area, and the thickness of the first area is less than the stacking thickness of the multiple pole tabs in the pole tab part, the multiple pole tabs in the second area are very tightly fitted with no or almost no interlayer gap, and relative to the first area, the interlayer gap in the second area is smaller than the interlayer gap in the first area, then the interlayer gap between the multiple pole tabs corresponding to at least most of the connecting part is very small, thereby improving the welding pores, explosion points and cracking caused by large interlayer gaps when the connecting part is subsequently welded to the pole, which is beneficial to improving the production qualification rate and reducing the production cost, and is beneficial to increasing the effective connection area between the connecting part and the pole, and can improve the connection strength, conductive reliability and current carrying capacity between the connecting part and the pole, thereby improving the reliability of the battery cell. In addition, it is also convenient to achieve that the thickness of the multiple pole tabs in the first area and the second area are both smaller than the stacking thickness of the multiple pole tabs, and the compaction degree of the multiple pole tabs in the second area is greater than the compaction degree in the first area. Moreover, since the depth of the second welding groove is relatively small, it is beneficial to reduce the risk of welding penetration during the forming process of the second area, which is beneficial to improving the welding stability.

[0006] In some embodiments, the connecting portion is located in the second region, and an outer edge of a portion of the connecting portion on the surface of the gathered portion is spaced apart from an edge of the second region.

[0007] In the above technical solution, the second area is effectively utilized to ensure good overall welding quality at the entire connection portion, which is beneficial to further improve the welding reliability between the pole ear and the pole or adapter.

[0008] In some embodiments, the second plurality of welding grooves are identical in shape and arrangement to the first plurality of welding grooves.

[0009] In the above technical solution, the first welding groove may be formed first, and then the corresponding part may be processed so that a part of the first welding groove is formed into the second welding groove, so as to facilitate subsequent processing.

[0010] In some embodiments, the first welding groove and the second welding groove are both formed as stepped grooves.

[0011] In the above technical solution, since the first welding groove and the second welding groove are both formed as stepped grooves, for any two adjacent groove portions, the portion of the bottom wall of the qth groove portion that exceeds the (q-1)th groove portion corresponding to the multiple pole tabs can be pressed and compacted during welding; during the welding process, the structure corresponding to the pth groove portion on the welding device contacts the pole tab before other portions, so as to achieve pre-pressing and shaping of local areas of the multiple pole tabs to reduce the gaps between the multiple pole tabs, and the above-mentioned structure corresponding to the pth groove portion on the welding device can compact and press the multiple pole tabs; as the welding device continues to apply pressure, the depth of the welding groove increases, and the portion of the bottom wall of each groove portion from the (p-1)th groove portion to the first groove portion that exceeds the corresponding groove portion can be pre-pressed and formed by the welding device for multiple times to further reduce the gaps between the multiple pole tabs, so that the multiple pole tabs are subjected to multi-layer pressing and multi-layer compaction by the welding device during the welding process, and the multiple pole tabs are not penetrated, thereby improving the problem of excessive intervals of multi-layer foil parts during welding, and facilitating the improvement of welding quality and welding stability.

[0012] In some embodiments, a third welding groove is further formed in the second region, and the third welding groove is located between two adjacent second welding grooves.

[0013] In the above technical scheme, the third welding groove and the first welding groove can be formed in different welding processes respectively. The third welding groove and the second welding groove are staggered, and the welding device can press and compact the local area between two adjacent second welding grooves in the second area, which is beneficial to improve the compaction area of ​​the welding device for multiple pole tabs. On the premise of basically not increasing the size of the welding head, it is beneficial to further reduce the interlayer gap between the multiple pole tabs and improve the welding quality.

[0014] In some embodiments, the third welding groove is formed as a stepped groove.

[0015] In the above technical solution, during the welding process, the local area between two adjacent second welding grooves in the second area can be subjected to multi-layer pier pressing and compaction, which is beneficial to further reduce the interlayer gap and facilitate further improving the welding quality.

[0016] In some embodiments, the gathering portion also includes a third area, which is arranged around the first area, and the third area is formed with a plurality of fourth welding grooves arranged at intervals. The plurality of fourth welding grooves are located at the edge of the first area and at the periphery of the plurality of first welding grooves, and the depth of the fourth welding grooves is less than the depth of the first welding grooves.

[0017] In the above technical solution, by arranging a plurality of fourth welding grooves at the edge position of the first area, the welding device can perform a certain pre-compression and shaping on the plurality of pole tabs at the position corresponding to the fourth welding groove, i.e., the edge of the first area. At the same time, since the welding device optimizes the friction area between the pole tab and itself into local surface friction, it is beneficial to reduce the local stress concentration of the pole tab and further improve the cracking of the pole tab.

[0018] In some embodiments, the gathered portion is directly welded to the pole; or, the battery cell further includes a transition piece, the gathered portion is indirectly connected to the pole via the transition piece, and the gathered portion is directly welded to the transition piece.

[0019] The above technical solution is conducive to increasing the effective connection area between the connecting part and the pole / adapter, and can improve the connection strength, conductive reliability and current carrying capacity between the connecting part and the pole / adapter.

[0020] In a second aspect, an embodiment of the present application provides a battery, comprising the above-mentioned battery cell.

[0021] In the above technical solution, since the battery adopts the above battery monomer and the reliability of the battery monomer is improved, the reliability of the battery can be improved.

[0022] In a third aspect, an embodiment of the present application provides an electrical device, comprising the above-mentioned battery.

[0023] In the above technical solution, since the electrical device adopts the above battery and the reliability of the battery is improved, it is beneficial to improve the working performance of the electrical device.

[0024] In a fourth aspect, an embodiment of the present application provides a welding device, characterized in that it is used to process the above-mentioned battery cell, and the welding device includes a first welding head and a second welding head, the first welding head is used to weld multiple pole ear sheets to form a first weld mark area, the second welding head is used to weld part of the first weld mark area to form a second weld mark area, the second weld mark area corresponds to the second area, and the part of the first weld mark area other than the second weld mark area includes the first area, the first welding head and the second welding head are both toothed welding heads, the first welding head includes a first main body and first welding teeth, the first welding teeth are multiple and spaced, and the multiple first welding teeth are convexly arranged on the welding surface of the first main body, the second welding head includes a second main body and a second welding tooth, the second welding teeth are multiple and spaced, and the multiple second welding teeth are convexly arranged on the welding surface of the second main body, and the protruding height of the second welding teeth is less than the protruding height of the first welding teeth.

[0025] In the above technical solution, the welding device can weld the multiple pole tabs at least twice to form the first area and the second area respectively, the number of welding times to form the second area is greater than the number of welding times to form the first area, and the welding process corresponding to the second area and the welding process corresponding to the first area overlap at least one welding process, so that the thickness of the multiple pole tabs in the first area and the thickness of the second area are both less than the stacking thickness of the multiple pole tabs in the pole tab part, and the compaction degree of the multiple pole tabs in the second area is greater than the compaction degree of the first area, while improving the welding quality at the connection part, it is beneficial to save the welding process of the multiple pole tabs, simplify the processing process of the battery cell, and improve the processing efficiency. When the first welding head welds the multiple pole tabs, the first welding teeth contact the pole tabs before the welding surface of the first body, so as to realize the pre-pressing and shaping of the local area of ​​the multiple pole tabs, which is beneficial to reduce the interlayer gap of the multiple pole tabs in the first welding area; the second welding head presses and compacts the multi-layer pole tabs through the second welding teeth during the welding process, so as to improve the problem that the interlayer gap of the multi-layer pole tabs is still large after at least one welding, so as to improve the welding quality and welding stability.

[0026] In some embodiments, the first welding tooth is formed as a stepped tooth.

[0027] In the above technical solution, since the first welding tooth is formed as a stepped tooth, when the first welding head welds the multi-layer pole tab sheet, each tooth portion can compact and press the multi-layer pole tab sheet to achieve multi-layer pressing and compacting of the welding material, effectively reducing the interlayer gap between the multi-layer pole tab sheets, thereby reducing the welding energy loss caused by the excessive interlayer gap between the multi-layer pole tab sheets. At the same time, the first welding tooth will not penetrate the multi-layer pole tab sheets, thereby improving the welding quality and welding efficiency.

[0028] In some embodiments, the second welding tooth is formed as a stepped tooth.

[0029] In the above technical solution, since the second welding tooth is formed as a stepped tooth, when the second welding head welds the multi-layer pole tab sheet, each tooth portion of the second welding tooth can compact and press the multi-layer pole tab sheet to achieve multi-layer pressing and compacting of the welding material, effectively reducing the large interlayer gap between the multi-layer pole tab sheets after welding, and at the same time, the second welding tooth will not penetrate the multi-layer pole tab sheets, thereby improving the welding quality and welding efficiency.

[0030] In some embodiments, the first welding head also includes a plurality of third welding teeth arranged at intervals, the plurality of third welding teeth are protruded on the welding surface of the first body, and are arranged on the periphery of the plurality of first welding teeth, and the height of the third welding teeth protruding from the welding surface is less than the height of the first welding teeth protruding from the welding surface.

[0031] In the above technical solution, the setting of the third welding tooth is conducive to increasing the compaction area of ​​the multi-layer pole ear sheet by the first welding head, and increasing the number of local areas where the multi-layer pole ear sheet is compacted by the first welding head, which is conducive to further improving the quality of ultrasonic welding; at the same time, the third welding tooth can perform a certain pre-stressing and shaping on the edge part of the first area, so as to realize the early pre-stressing and shaping of the multi-layer pole ear sheet, and the third welding tooth can optimize the friction area between the pole ear sheet and the first welding head from large-surface friction to local surface friction, reduce the local stress concentration of the pole ear sheet, and further improve the cracking of the pole ear sheet.

[0032] In some embodiments, the first horn is an ultrasonic horn and the second horn is a resistance horn.

[0033] In the above technical solution, resistance welding utilizes the resistance heat effect generated by the current flowing through the contact surface of the workpiece and the adjacent area to heat it to a molten or plastic state so that it can be combined. Resistance welding can reduce or eliminate the interlayer gaps between the multilayer pole tabs after ultrasonic welding, further improve the compaction degree of the corresponding area, and achieve a greater compaction degree in the second area than in the first area.

[0034] In a fifth aspect, an embodiment of the present application provides a welding method, which uses the above-mentioned welding device to process multiple pole tabs, and the welding method includes: stacking multiple pole tabs; using a first welding head to weld the overlapping parts of the multiple pole tabs to form a first weld print area; using a second welding head to weld at least part of the first weld print area to form a second weld print area.

[0035] In the above technical solution, multiple pole tabs are welded multiple times by a welding device, so that the intersection of the first weld mark area formed by the first welding head and the second weld mark area formed by the second welding head forms a second area, so that the second area has no or almost no interlayer gap, so that the part of the gathered part corresponding to the second area can form a dense plate-like structure, which is conducive to achieving crack-free and reliable connection between the connecting part and the pole / transfer sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0037] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0038] Figure 2 An exploded view of the structure of a battery provided in some embodiments of the present application;

[0039] Figure 3 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0040] Figure 4for Figure 3 A schematic diagram of an electrode assembly of a battery cell shown in ;

[0041] Figure 5 for Figure 4 A partial schematic diagram of an electrode assembly shown in , wherein the dotted area is the first area, the sum of the oblique line area and the oblique line grid area is the second area, and the oblique line grid area is the connecting portion;

[0042] Figure 6 for Figure 5 A schematic diagram of the connection of the electrode assembly shown in ;

[0043] Figure 7 for Figure 5 Another connection schematic diagram of the electrode assembly shown in ;

[0044] Figure 8 A schematic diagram of the structure of a welding device provided in some embodiments of the present application;

[0045] Fig. 9 for Figure 8 The enlarged view of the circled section A;

[0046] Fig.10 for Fig. 9 A schematic diagram of a first welding head shown in ;

[0047] Fig.11 for Fig.10 A schematic diagram of a first welding head shown in ;

[0048] Fig.12 A schematic diagram of the structure of a second welding head provided in some embodiments of the present application;

[0049] Fig.13 for Fig.12 Another schematic diagram of the second welding head shown in ;

[0050] Fig.14 A schematic diagram of the structure of a second welding head provided in some embodiments of the present application;

[0051] Fig.15 for Fig.14 Another schematic diagram of the second welding head shown in ;

[0052] Fig.16 A schematic diagram of the structure of a second welding head provided in some embodiments of the present application;

[0053] Fig.17 for Fig.16 Another schematic diagram of the second welding head shown in ;

[0054] Fig.18 A schematic diagram of a welding method flow chart provided in some embodiments of the present application;

[0055] Fig.19 for Fig.18 In the welding process schematic diagram shown in , the oblique line area is the first weld mark area, and the oblique line grid area is the second weld mark area.

[0056] Reference numerals:

[0057] The electric device 1000, the battery 200, the controller 300, the motor 400, the battery cell 100, the box 101, the first box body 101a, the second box body 101b,

[0058] Shell 1, pole 2, electrode assembly 3, pole ear portion 31, pole ear sheet 311, gathering portion 312, first region 3121, second region 3122, connecting portion 313, active material coating portion 32, adapter 4, first weld 51, first portion 511, second portion 512, second weld 52, third portion 521, fourth portion 522,

[0059] Welding device 500, transition surface S,

[0060] The first welding head 501, the first welding mark area 501a, the first body 5011, the welding surface R, the first welding tooth 5012, the third welding tooth 5013, the second welding head 502, the second welding mark area 502a, the second body 5021, the second welding tooth 5022, the stepped tooth 503, and the tooth portion 503a. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0062] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0063] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0064] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, they can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0065] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0066] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of the various components in the embodiments of the present application shown in the drawings are only exemplary and should not constitute any limitation to the present application.

[0067] The term “plurality” used in this application refers to two or more (including two).

[0068] In the present application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries or magnesium-ion batteries, etc., and the embodiments of the present application do not limit this. Battery cells may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present application do not limit this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application do not limit this.

[0069] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may be a battery module or a battery pack. A battery module generally includes a plurality of battery cells. The battery generally includes a casing for encapsulating one or more battery cells or one or more battery modules, and the casing can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells; of course, the battery may not include a casing.

[0070] Exemplarily, a battery cell may generally include a shell, an electrode assembly and an electrolyte, wherein the shell is used to contain the electrode assembly and the electrolyte. At least one electrode assembly is contained in the shell, and at least one positive electrode column and at least one negative electrode column are provided on the shell; the electrode assembly is formed by stacking or winding a positive electrode sheet, a negative electrode sheet and a separator.

[0071] Among them, the positive electrode sheet can generally include a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is directly or indirectly coated on the positive electrode current collector, the positive electrode current collector not coated with the positive electrode active material layer protrudes from the positive electrode current collector coated with the positive electrode active material layer, the positive electrode current collector not coated with the positive electrode active material layer serves as a positive electrode tab sheet, and a plurality of positive electrode tab sheets are stacked together and electrically connected to the positive electrode column. Exemplarily, the plurality of stacked positive electrode tab sheets can be directly welded to the positive electrode column to form an electrical connection; or, the electrode assembly can also include a positive electrode adapter sheet, the plurality of stacked positive electrode tab sheets are welded to one end of the positive electrode adapter sheet, and the other end of the positive electrode adapter sheet is welded to the positive electrode column, so that the positive electrode tab sheet is electrically connected to the positive electrode column.

[0072] The negative electrode sheet can generally include a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is directly or indirectly coated on the negative electrode current collector, the negative electrode current collector not coated with the negative electrode active material layer protrudes from the negative electrode current collector coated with the negative electrode active material layer, the negative electrode current collector not coated with the negative electrode active material layer serves as a negative electrode tab sheet, and a plurality of negative electrode tab sheets are stacked together and electrically connected to the negative electrode column. Exemplarily, a plurality of negative electrode tab sheets stacked together can be directly welded to the negative electrode column to form an electrical connection; or, the electrode assembly can also include a negative electrode adapter sheet, a plurality of negative electrode tab sheets stacked together are welded to one end of the negative electrode adapter sheet, and the other end of the negative electrode adapter sheet is welded to the negative electrode column, so that the negative electrode tab sheet is electrically connected to the negative electrode column. The material of the separator is not limited, for example, it can be polypropylene or polyethylene.

[0073] In order to ensure that a large current does not melt, there are multiple positive electrode tabs stacked together to form the positive electrode tab, and multiple negative electrode tabs stacked together to form the negative electrode tab. The shell is provided with a pole column, the positive electrode tab is electrically connected to the positive pole column, and the negative electrode tab is electrically connected to the negative pole column.

[0074] In the related art, the pole ear and pole column are the key components of the power battery, and they play an important role in overcurrent and current diversion. For the battery with a non-adapter structure, usually, the stacked multi-layer pole ear sheets are welded together by ultrasonic welding to form a plate-shaped pole ear part, and then the plate-shaped pole ear part after welding is welded to the corresponding pole column by laser welding to achieve connection and electrical conduction with the pole column. However, due to the insufficient pressure and energy provided by the ultrasonic welding device, the uniform welding teeth cannot make the pole ear part form a solid plate that is melted into one, but presents a virtual welding plate of multi-layer foil, and there are gaps between the foils. Therefore, when the pole ear part is laser welded with the pole column, these gaps will cause welding pores, explosion points and cracks, and the local temperature rise of the pole column is too fast, and cracks will appear at the edge of the formed laser weld, which affects the conductivity yield and connection strength of the pole ear part and the pole column, thereby affecting the reliability of the battery cell.

[0075] Based on the above considerations, an embodiment of the present application proposes a battery cell, including a shell, a pole and an electrode assembly, the electrode assembly is accommodated in the shell and includes a pole ear portion, the pole ear portion includes a plurality of pole ear sheets, the plurality of pole ear sheets are stacked and connected to form a gathered portion, and a connecting portion is formed at a position of the gathered portion for electrical connection with the pole; wherein the gathered portion includes an adjacent first area and a second area, the degree of compaction of the plurality of pole ear sheets in the second area is greater than the degree of compaction in the first area, the thickness of the plurality of pole ear sheets in the first area is less than the stacking thickness of the plurality of pole ear sheets in the pole ear portion, and at least most of the connecting portion falls in the second area.

[0076] In the above technical solution, since at least most of the connecting part falls within the second area, and the degree of compaction of the multiple pole tabs in the second area is greater than that in the first area, and the thickness of the first area is less than the stacking thickness of the multiple pole tabs in the pole tab part, the multiple pole tabs in the second area are very tightly fitted with no or almost no interlayer gap, and relative to the first area, the interlayer gap in the second area is smaller than the interlayer gap in the first area, then the interlayer gap between the multiple pole tabs corresponding to the above at least most of the connecting part is very small or almost no gap, thereby improving the welding pores, explosion points and cracking caused by large interlayer gaps when the connecting part is subsequently welded to the pole, which is beneficial to improving the production qualification rate and reducing the production cost, and is beneficial to increasing the effective connection area between the connecting part and the pole, and can improve the connection strength, conductive reliability and current carrying capacity between the connecting part and the pole, thereby improving the reliability of the battery cell.

[0077] The embodiment of the present application provides an electric device using the battery disclosed in the present application as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc., the electric tool may include a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator, and an electric planer, etc.

[0078] For the convenience of description, the following embodiments take the electric device 1000 as a vehicle as an example, and describe in detail the structures of the electric device 1000, the battery 200 and the battery cell 100 of the present application.

[0079] Please refer to Figure 1 , Figure 1 The power consumption device 1000 provided for some embodiments of the present application is a structural schematic diagram of a vehicle. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. The vehicle is provided with a battery 200, and the battery 200 can be arranged at the bottom, head or tail of the vehicle. The battery 200 can be used to power the vehicle, for example, the battery 200 can be used as an operating power source for the vehicle. The vehicle may also include a controller 300 and a motor 400, and the controller 300 is used to control the battery 200 to power the motor 400, for example, for the starting, navigation and working power requirements of the vehicle during driving. In some embodiments of the present application, the battery 200 can be used not only as the operating power source of the vehicle, but also as the driving power source of the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0080] Please refer to Figure 2 , Figure 2An exploded diagram of the structure of a battery 200 provided in some embodiments of the present application. The battery 200 includes a case 101 and a plurality of battery cells 100, and the battery cells 100 are accommodated in the case 101. The case 101 is used to provide an assembly space for the battery cells 100, and the case 101 can adopt a variety of structures. In some embodiments, the case 101 may include a first box body 101a and a second box body 101b, the first box body 101a and the second box body 101b cover each other, and the first box body 101a and the second box body 101b jointly define a receiving cavity for accommodating the battery cells 100. The second box body 101b may be a hollow structure with one end open, and the first box body 101a may be a plate-like structure, and the first box body 101a covers the open side of the second box body 101b, so that the first box body 101a and the second box body 101b jointly define a receiving cavity; or, the first box body 101a and the second box body 101b may also be hollow structures with one side open (for example Figure 2 As shown in FIG. 1 , the open side of the first box body 101a covers the open side of the second box body 101b. Of course, the box body 101 formed by the first box body 101a and the second box body 101b can be in various shapes, such as a cylinder or a cuboid.

[0081] In the battery 200, multiple battery cells 100 can be connected in series, in parallel or in a mixed connection. A mixed connection means that multiple battery cells 100 are connected in series and in parallel. Multiple battery cells 100 can be directly connected in series, in parallel or in a mixed connection, and then the whole formed by multiple battery cells 100 is accommodated in the box 101; or, the battery 200 can also be a battery module formed by multiple battery cells 100 connected in series, in parallel or in a mixed connection, and then multiple battery modules are connected in series, in parallel or in a mixed connection to form a whole, and accommodated in the box 101. The battery 200 may also include other structures, for example, the battery 200 may also include a busbar for realizing electrical connection between multiple battery cells.

[0082] Each battery cell 100 may be a primary battery or a secondary battery; it may also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto. The battery cell 102 may be a polygonal prism, a cylinder, a flat body, a cuboid, etc. Exemplarily, the battery cell 102 is a cuboid, and the height direction of the battery cell is the third direction Z, the length direction of the battery cell is the second direction Y, and the thickness direction of the battery cell is the first direction X. The first direction X, the second direction Y and the third direction Z are perpendicular to each other. But it is not limited thereto.

[0083] Please refer to Figure 3-Figure 5In an embodiment of the present application, a battery cell 100 includes a shell 1, a pole 2 and an electrode assembly 3. The pole 2 is disposed in the shell 1, and the electrode assembly 3 is accommodated in the shell 1, then at least a portion of the electrode assembly 3 is disposed in the shell 1; the electrode assembly 3 includes a pole ear portion 31, and the pole ear portion 31 is electrically connected to the pole 2, then the pole ear portion 31 is directly or indirectly electrically connected to the pole 2 to achieve electrical conduction between the pole ear portion 31 and the pole 2.

[0084] Among them, the structure of the shell 1 is not specifically limited; for example, the shell 1 may include a shell body and a shell cover, the shell body defines a cavity with one end closed and the other end open, the shell cover is arranged on the open end of the shell body, and the shell cover is roughly formed into a flat plate shape. The pole 2 can be installed on the shell cover, or the pole 2 is installed on the shell wall of the shell body opposite to the shell cover; for another example, the shell 1 includes two half shells arranged in opposition, each half shell defines a cavity open toward the other half shell, and the pole 2 can be installed on the shell wall of one of the half shells at one end away from the other half shell.

[0085] It can be understood that the electrode assembly 3 further includes an active material coating portion 32, which is disposed in the housing 1, and the pole ear portion 31 is electrically connected to the active material coating portion 32. For example, the pole ear portion 31 is welded to the pole 2, so that the pole ear portion 31 is directly electrically connected to the pole 2, and the pole ear portion 31 is electrically connected between the active material coating portion 32 and the pole 2; for another example, a transfer plate 4 is connected between the pole ear portion 31 and the pole 2, one end of the transfer plate 4 is welded to the pole ear portion 31, and the other end of the transfer plate 4 is welded to the pole 2, so that the pole ear portion 31 is indirectly electrically connected to the pole 2 through the transfer plate 4.

[0086] Combination Figure 3-Figure 7 The pole ear portion 31 includes a plurality of pole ear sheets 311, and the plurality of pole ear sheets 311 are stacked and connected to form a gathering portion 312. The gathering portion 312 is formed at the overlapping portion of the plurality of pole ear sheets 311, and the plurality of pole ear sheets 311 are connected corresponding to the positions of the gathering portion 312. In other words, the plurality of pole ear sheets 311 of the gathering portion 312 not only present a stacked arrangement relationship, but also have a connection relationship, for example, the plurality of pole ear sheets 311 are stacked and welded to form the gathering portion 312.

[0087] The gathering portion 312 includes an adjacent first area 3121 and a second area 3122, and the multiple pole ear sheets 311 of the first area 3121 are connected and arranged, and the multiple pole ear sheets 311 of the second area 3122 are also connected and arranged, and part of the outer edge of the first area 3121 overlaps with part of the outer edge of the second area 3122. The first area 3121 and the second area 3122 can jointly define a polygonal area or a circular area, but are not limited to this, for example, it can also be other special-shaped areas.

[0088] Exemplarily, the first region 3121 and the second region 3122 have the same shape, for example, the first region 3121 and the second region 3122 are respectively formed as square regions, and the first region 3121 and the second region 3122 can be arranged in sequence along the width direction of the first region 3121. In some other examples, the first region 3121 and the second region 3122 have different shapes, for example, the first region 3121 extends and bends around the circumference of the second region 3122, then the first region 3121 can be formed into an open ring or a closed ring, and the first region 3121 bends once or multiple times along the circumference of the second region 3122. For example, the first region 3121 can be roughly formed into an L-shape, a U-shape, a C-shape, a circular ring, or a polygonal ring, etc. Since the second region 3122 is located in the area defined by the first region 3121, the outer edges of the first region 3121 in at least two directions are aligned with the outer edges of the second region The corresponding edges of 3122 are spaced apart, and the second area 3122 can be formed into a continuous area, or include a plurality of spaced-apart sub-areas; for example, the first area 3121 is U-shaped, and the inner edge of the first area 3121 can define the U-shaped area, the second area 3122 is arranged in the U-shaped area, and the outer edge of the second area 3122 overlaps with the edge of the U-shaped area; for another example, the first area 3121 is a square annular area, and the inner edge of the first area 3121 is the outer edge of the second area 3122. At this time, the outer edge of the first area 3121 is spaced apart from the outer edge of the second area 3122.

[0089] The thickness of the plurality of pole tabs 311 in the first region 3121 is less than the stacking thickness of the plurality of pole tabs 311 in the pole tab portion 31, and the thickness T1 of the plurality of pole tabs 311 in the first region 3121 is less than the theoretical thickness T of the pole tab portion 31. Therefore, since the thickness T1 of the first region 3121 is less than the theoretical thickness T of the pole tab portion 3132, it is explained that the pole tabs 311 in the first region 3121 are compressed and yielded and plastically deformed, the thickness of the pole tabs 311 is thinned, and the multiple layers of pole tabs 311 in the first region 3121 are closely combined together, and the interlayer gap is relatively small, so that the first region 3121 can be formed as a compacted region, and the compaction rate of the first region 3121 is greater than 0%.

[0090] For example, the "compaction rate" of the first region 3121 refers to: the ratio of the difference between the theoretical thickness T of the pole ear portion 31 and the thickness T1 of the first region 3121 to the theoretical thickness T of the pole ear portion 31, that is, (T-T1) / T. The theoretical thickness T refers to the stacking thickness of multiple pole tab sheets 311 in the pole ear portion 31 before connection, that is, the thickness of the pole tab sheets 311 that are not compressed and stacked together without gaps. For example, the thickness of a single pole tab sheet 311 is a (that is, a is the thickness of a single layer of foil), and b layers of pole tab sheets 311 are stacked in the pole ear portion 31 (that is, b is the number of layers of foil), then the stacking thickness of the multiple pole tab sheets 311 in the pole ear portion 31 before connection is a×b, so the theoretical thickness T of the pole ear portion 31 is a×b. Exemplarily, the thickness T1 of the first region 3121 can be the average thickness of the first region 3121, or the maximum thickness of the first region 3121.

[0091] Moreover, the degree of compaction of the multiple pole tabs 311 in the second area 3122 is greater than the degree of compaction in the first area 3121, then the thickness T2 of the multiple pole tabs 311 in the second area 3122 is less than the thickness T1 in the first area 3121, and the thickness of the multiple pole tabs 311 in the second area 3122 is less than the stacking thickness of the multiple pole tabs 311; it can be seen that the thickness of the multiple pole tabs 311 in the first area 3121 and the thickness in the second area 3122 are both less than the theoretical thickness T of the pole tab portion 31, and the multi-layer pole tabs 311 in the second area 3122 are more closely combined together than the multi-layer pole tabs 311 in the first area 3121, the interlayer gap in the second area 3122 is relatively smaller, there is no or almost no interlayer gap, and similarly the second area 3122 can also be formed as a compacted area, and the compaction rate of the second area 3122 is greater than 0%.

[0092] It is worth noting that the "compactness" described in the present application refers to the degree of tightness between the layers of the multi-layered tab sheets 311. The smaller the compactness, the greater the thickness, and the greater the compactness, the smaller the thickness. Exemplarily, the thickness of the multiple tab sheets 311 in the first area 3121 can be the average thickness of the multiple tab sheets 311 in the first area 3121, or the maximum thickness of the multiple tab sheets 311 in the first area 3121; the thickness of the multiple tab sheets 311 in the second area 3122 can be the average thickness of the multiple tab sheets 311 in the second area 3122, or the maximum thickness of the multiple tab sheets 311 in the second area 3122.

[0093] Recombination Figure 5-Figure 7, a connection portion 313 is formed at a position of the gathered portion 312 for electrical connection with the pole 2, and the connection portion 313 is directly or indirectly electrically connected to the pole 2 to achieve electrical conduction between the pole ear portion 31 and the pole 2; at least most of the connection portion 313 falls in the second area 3122, which can be understood as: the outer edge of the portion of the connection portion 313 on the surface of the gathered portion 312 is the contour line of the connection portion 313, and at least most of the contour line falls in the second area 3122, indicating that more than 50% (including 50%) of the contour line is located in the second area 3122; and / or, on the plane where the pole tab 311 is located, at least most of the orthographic projection area of ​​the connection portion 313 falls in the second area 3122, indicating that more than 50% (including 50%) of the above-mentioned orthographic projection area of ​​the connection portion 313 is located in the second area 3122, and the plane where the pole tab 311 is located is perpendicular to the thickness direction of the pole tab 311 and is also perpendicular to the stacking direction of the plurality of pole tabs 311.

[0094] For example, the contour lines of the portion of the connecting portion 313 on the surface of the gathering portion 312 are all located in the second area 3122; for another example, a portion of the contour lines of the portion of the connecting portion 313 on the surface of the gathering portion 312 is located in the second area 3122, and the remaining portion is located in the first area 3121, and the proportion of the contour lines located in the second area 3122 is greater than the proportion of the contour lines located in the first area 3121; for another example, a portion of the contour lines of the portion of the connecting portion 313 on the surface of the gathering portion 312 is located in the second area 3122, a portion is located in the first area 3121, and the remaining portion is located outside the gathering portion 312, and the proportion of the contour lines located in the second area 3122 is the largest.

[0095] Exemplarily, the number of corresponding welding times for forming the second region 3122 is greater than the number of corresponding welding times for forming the first region 3121, so that the compaction degree of the plurality of pole tabs 311 in the second region 3122 is greater than the compaction degree of the plurality of pole tabs 311 in the first region 3121; further optionally, under the premise that the number of corresponding welding times for forming the second region 3122 is greater than the number of corresponding welding times for forming the first region 3121, the welding process corresponding to the second region 3122 and the welding process corresponding to the first region 3121 overlap at least one welding process, then during the welding process, there is at least one welding process for welding the first region 3121 and the second region 3122 simultaneously; for example, the first region 3121 and the second region 3121 are first welded, and then the first region 3121 and the second region 3122 are welded simultaneously. The area formed by the domain 3122 (for example, the first weld stamp area 501a described later) is welded once to weld the multiple pole tabs 311 in the above-mentioned area formed by the first area 3121 and the second area 3122, and then the second area 3122 (for example, the intersection of the second weld stamp area 502a described later and the first weld stamp area 501a) is welded again to weld the multiple pole tabs 311 again in the second area 3122. At this time, the first area 3121 can be formed after one welding, and the second area 3122 can be formed after two weldings, and one of the welding in the second area 3122 and the one welding corresponding to the first area 3121 are the same welding process.

[0096] Exemplarily, the connecting portion 313 is formed on the gathering portion 312, and the connecting portion 313 is welded to the pole 2. The connecting portion 313 can participate in forming a weld formed by the electrical connection between the pole ear portion 31 and the pole 2. For example, the gathering portion 312 is directly welded to the pole 2, and the connecting portion 313 participates in forming a first weld 51 between the connecting portion 313 and the pole 2. For another example, the gathering portion 312 is indirectly connected to the pole 2 through the adapter plate 4, and the gathering portion 312 is directly welded to the adapter plate 4, and the connecting portion 313 participates in forming a second weld 52 between the pole ear portion 31 and the adapter plate 4. Obviously, taking the first weld 51 as an example, the first weld 51 may include a first portion 511 formed on the gathered portion 312 and a second portion 512 formed on the pole 2. It can be understood that the first weld 51 needs to connect the gathered portion 312 and the pole 2, then part of the first weld 51 is formed on the gathered portion 312, this portion is the first portion 511, and the remaining portion is formed on the pole 2, this portion is the second portion 512, the first portion 511 is the connection portion 313, at least most of the first portion 511 falls on the second area 3122, and the compaction degree of the second area 3122 is relatively large, which is conducive to increasing the effective connection area between the connection portion 313 and the pole 2, and can improve the connection strength, conductive reliability and current carrying capacity between the connection portion 313 and the pole 2 / adapter 4; similarly, the second weld 52 may include a third portion 521 formed on the gathered portion 312 and a fourth portion 522 formed on the adapter 4, the third portion 521 is the connection portion 313.

[0097] Taking the laser welding of the gathering portion 312 and the pole 2 / adapter 4 as an example, the weld is a laser weld. When laser welding is performed from the side of the gathering portion 312 away from the pole 2 / adapter 4, the first part of the connection portion 313 formed on the gathering portion 312 may include: a surface part formed on the outer surface of the gathering portion 312, and an internal part formed in the gathering portion 312. At this time, the contour line of the surface part and the internal part at the boundary position of the surface of the gathering portion 312 is the contour line of the part of the connection portion 313 on the surface of the gathering portion 312. Alternatively, if laser welding is performed from the side of the pole 2 / adapter 4 away from the gathering portion 312, the first part of the connection portion 313 formed on the gathering portion 312 may only include: an internal part formed in the gathering portion 312. At this time, the contour line of the internal part on the surface of the gathering portion 312 constitutes the contour line of the part of the connection portion 313 on the surface of the gathering portion 312. It can be understood that when the connecting portion 313 participates in forming a weld, the folded portion 312 and the pole 2 / adapter plate 4 can be connected by one or multiple welds. For example, in the case of a single weld, the welding is completed in one time, and in the case of multiple welds, the welding can be completed in multiple times.

[0098] Of course, the retracted portion 312 and the pole 2 / adapter 4 may also be connected in other ways, such as arc welding, ion welding, gas welding, electron beam welding, etc.

[0099] The first region 3121 is formed with a plurality of first welding grooves disposed at intervals, and the second region 3122 is formed with a plurality of second welding grooves disposed at intervals.

[0100] It can be seen that the parts of the welding device 500 corresponding to the first welding groove and the second welding groove (such as the welding teeth described later) can press and compact the multiple pole tabs 311 during the welding process. That is to say, during welding, the parts of the welding device 500 that can form the first welding groove and the second welding groove contact the pole tab 311 before other parts, so as to achieve pre-pressing and shaping of local areas of the multiple pole tabs 311 to reduce the gaps between the multiple pole tabs 311.

[0101] Furthermore, the depth of the second welding groove is less than the depth of the first welding groove. In this case, the first welding groove can be formed first, and then the corresponding part is processed to make a part of the first welding groove form a second welding groove, and / or the corresponding part is processed again to form a second welding groove on the second area, so as to facilitate subsequent processing.

[0102] For example, a first welding head 501 configured as a welding head with teeth is first used to weld a plurality of pole tabs 311 to form a first weld area 501a, at which time a first welding groove is formed on the first weld area 501a, and then a second welding head 502 configured as a welding head with teeth is used to weld at least a portion of the first weld area 501a again to form a second weld area 502a, at which time a second welding groove can also be formed on the second weld area 502a, at least a portion of the second welding groove can be formed by the welding teeth of the second welding head 501, and the protruding height of the welding teeth of the second welding head can be less than the protruding height of the welding teeth of the first welding head. Thus, the first welding head 501 can form a first welding groove, and the first weld area 501a is uneven, and then the second welding head 501 configured as a welding head with teeth is used for re-welding, so that the second welding head 502 can reshape and flatten a portion of the first weld area 501a, which is also convenient for reducing the interlayer gap between the plurality of pole tabs 311.

[0103] Alternatively, multiple pole tabs 311 are welded, and the welding teeth on the welding head can form a first welding groove on the pole tab portion 31. At this time, multiple first welding grooves are formed in the first area 3121 and the second area 3122 respectively, and then the second area 3122 is welded again to reduce the depth of the first welding groove in the second area 3122, so that the first welding groove in the second area 3122 is formed into a second welding groove after the depth is reduced; for example, a first welding head 501 configured as a toothed welding head is first used to weld multiple pole tabs 311 to form a first weld print area 501a. At this time, a first welding groove is formed on the first weld print area 501a, and then a second welding head 502 configured as a toothless welding head is used to weld at least part of the first weld print area 501a again to form a second weld print area 502a. At this time, each of the original first welding grooves on the second weld print area 502a is respectively formed into a second welding groove. Therefore, since the first welding head 501 can form the first welding groove, the first weld print area 501a is uneven, and then the second welding head 502 configured as a toothless welding head is used for re-welding, so that the second welding head 502 can reshape and flatten part of the first weld print area 501a, which is beneficial to further reduce the interlayer gap between the multiple pole tabs 311.

[0104] In the above technical solution, since at least most of the connecting portion 313 falls within the second region 3122, and the compaction degree of the plurality of pole tabs 311 in the second region 3122 is greater than the compaction degree in the first region 3121, and the thickness of the first region 3121 is less than the stacking thickness of the plurality of pole tabs 311 in the pole tab portion 31, the plurality of pole tabs 311 in the second region 3122 fit very closely, with no or almost no interlayer gap, and relative to the first region 3121, the interlayer gap in the second region 3122 is less than the interlayer gap in the first region 3121. If the gap is large, the interlayer gap between the plurality of pole tabs 311 corresponding to at least most of the above-mentioned connecting portion 313 is very small, so that the welding pores, explosion points and cracking caused by the large interlayer gap when the connecting portion 313 is subsequently welded to the pole 2 can be improved, which is conducive to improving the production qualification rate and reducing the production cost, and is conducive to increasing the effective connection area between the connecting portion 313 and the pole 2, and can improve the connection strength, conductive reliability and current carrying capacity between the connecting portion 313 and the pole 2, so as to improve the reliability of the battery cell 100. In addition, it is also convenient to realize that the thickness of the plurality of pole tabs 311 in the first area 3121 and the second area 3122 is less than the stacking thickness of the plurality of pole tabs 311, and the compaction degree of the plurality of pole tabs 311 in the second area 3122 is greater than the compaction degree in the first area 3121, and because the depth of the second welding groove is relatively small, it is conducive to reducing the risk of welding penetration in the second area 3122 during the molding process, and is conducive to improving the welding stability.

[0105] It can be understood that when the interlayer gap of the multi-layered pole tab 311 is large, there is a large air gap between the layers. When laser welding is performed here with the pole 2 / adapter 4, the welding heat of the laser welding is blocked by the large air gap, and the heat stays in the air gap for a long time, which easily burns the pole tab 311 and forms cracks. In the embodiment of the present application, since the multi-layered pole tab 311 in the second area 3122 is melted into one, relatively compacted, and the interlayer gap is small or there is no interlayer gap, the heat of the laser welding can be conducted faster in the second area 3122, improving the problem of heat staying in a certain place for a long time and burning the pole tab 311 to form cracks.

[0106] In addition, since the thickness of the plurality of pole tabs 311 in the first area 3121 and the thickness of the second area 3122 are both smaller than the stacked thickness of the plurality of pole tabs 311 in the pole tab portion 31, it is convenient to make the folded portion 312 have a certain rigidity, which is convenient for assembling the pole tab portion 31 with other components. For example, if the pole tab portion 31 needs to penetrate the avoidance portion of other components (for example, the pole tab portion 31 first penetrates the through hole on the pole column 2, and then the pole tab portion 31 is welded to the pole column 2), the convenience of penetrating the pole tab portion 31 can be improved, and the assembly convenience and assembly efficiency of the battery cell 100 can be improved.

[0107] Please refer to Figure 5-Figure 7 In some embodiments, the connecting portion 313 falls on the second region 3122 , and the outer edge of the portion of the connecting portion 313 on the surface of the gathering portion 312 is spaced apart from the edge of the second region 3122 .

[0108] Therefore, the second area 3122 can be effectively utilized to ensure good overall welding quality at the entire connecting portion 313 , which is beneficial to further improve the welding reliability between the pole lug portion 31 and the pole 2 or the adapter plate 4 .

[0109] For example, Figure 5 As shown, the first area 3121 is arranged around the second area 3122, so that the first area 3121 forms a closed ring, and the center of the first area 3121 can coincide with the center of the second area 3122; for example, the area formed by the first area 3121 and the second area 3122 is first welded to weld the multiple pole tabs 311 in the above area, and then the second area 3122 is welded again to weld the multiple pole tabs 311 in the second area 3122 again, so that the compaction degree of the second area 3122 is greater.

[0110] Optionally, the second region 3122 is the region with the greatest degree of compaction on the gathered portion 312. For example, the gathered portion 312 includes a corresponding portion of the union of regions formed after performing n welding on the plurality of pole tabs 311, where n ≥ 2 and is a positive integer, the latter welding region is referenced to the former welding region, and the weld marks formed by any two adjacent weldings respectively have intersections (for example, the intersection of the weld marks formed by any two adjacent weldings is the weld marks formed by the latter welding in the corresponding two adjacent weldings), so that the gathered portion 312 includes a plurality of regions with different degrees of compaction, wherein the region with the greatest degree of compaction, that is, the region with the smallest interlayer spacing, such as the region with the smallest thickness of the gathered portion 312, is the second region 3122. In this way, the welding defects such as welding porosity, explosion points and cracking caused by large interlayer gaps when the connecting part 313 is subsequently welded to the pole 2 / adapter plate 4 can be improved more effectively, which is conducive to better improving the welding quality of the connecting part 313, increasing the effective connection area between the connecting part 313 and the pole 2 / adapter plate 4, and improving the reliability of the battery cell 100.

[0111] Taking n=2 as an example, a first weld mark area is formed after the first welding of multiple pole tabs 311, and a second weld mark area is formed after the second welding of multiple pole tabs 311. The first weld mark area and the second weld mark area have an intersection, and the intersection of the first weld mark area and the second weld mark area is the second area 3122. The first weld mark area except the second area 3122 is the first area 3121. Taking n=3 as an example, after the first welding of the plurality of pole tabs 311, a first weld mark area is formed, after the second welding of the plurality of pole tabs 311, a second weld mark area is formed, and after the third welding of the plurality of pole tabs 311, a third weld mark area is formed. The first weld mark area, the second weld mark area and the third weld mark area have an intersection, and the intersection of the first weld mark area, the second weld mark area and the third weld mark area is the second area 3122. The second weld mark area except the second area 3122 is the first area 3121. At this time, there is also a third area in the gathering portion 312, and the compaction degree of the plurality of pole tabs 311 in the first area 3121 is greater than the compaction degree in the third area. Of course, in other embodiments of the present application, n can also be greater than 3.

[0112] Of course, in other embodiments of the present application, the first area 3121 may not be formed with the first welding groove. In this case, the second area 3122 may not be formed with the second welding groove, or may be formed with the second welding groove; in other words, the second welding groove on the second area 3122 may be formed by the first welding groove, or may be formed separately during the welding process of the second area 3122.

[0113] The following takes the example of first welding multiple pole tabs 311 using the first welding head 501 and then welding multiple pole tabs 311 using the second welding head 502: the first welding head 501 welds multiple pole tabs 311 to form a first weld print area 501a, and the second welding head 502 welds at least part of the first weld print area 501a again to form a second weld print area 502a, and the intersection of the first weld print area 501a and the second weld print area 502a can be the second area 3122. When the depth of the second welding groove of the second area 3122 is less than the depth of the first welding groove of the first area 3121, the following examples can be included: Example 1, the first welding head 501 is a toothed welding head, and the second welding head 502 is a toothless welding head; Example 2, the first welding head 501 is a toothless welding head, and the second welding head 502 is a toothed welding head, and the second welding head 502 can have welding teeth with different protruding heights; Example 3, the first welding head 501 and the second welding head 502 are both toothed welding heads.

[0114] Among them, a toothless welding head can be understood as a welding head on which no welding teeth are arranged on the welding surface R, and the entire welding surface R of the welding head is a smooth surface; a toothed welding head can be understood as a welding head on which welding teeth are convexly arranged on the welding surface R; the welding types of the first welding head 501 and the second welding head 502 can be the same or different, for example, the first welding head 501 and the second welding head 502 can both realize ultrasonic welding, or, the first welding head 501 is used to realize ultrasonic welding, and the second welding head 502 is used to realize resistance welding.

[0115] In some embodiments, the multiple second welding grooves are the same in shape and arrangement as the multiple first welding grooves, and the depth of the second welding groove is less than the depth of the first welding groove. At this time, the first welding groove can be formed first, and then the corresponding part can be processed so that a part of the first welding groove is formed into the second welding groove, so as to facilitate subsequent processing.

[0116] Exemplarily, a first welding head 501 configured as a toothed welding head is first used to weld multiple pole tabs 311 to form a first weld print area 501a. At this time, a first welding groove is formed on the first weld print area 501a. Then, a second welding head 502 configured as a toothless welding head is used to weld at least part of the first weld print area 501a again to form a second weld print area 502a. At this time, each original first welding groove on the second weld print area 502a is respectively formed as a second welding groove. Therefore, since the first welding head 501 can form the first welding groove, the first weld print area 501a is uneven, and then the second welding head 502 constructed as a toothless welding head is used for re-welding, so that the second welding head 502 can reshape and flatten part of the first weld print area 501a, which is beneficial to further reduce the interlayer gap between the multiple pole tabs 311; of course, even if the first welding head 501 is a toothless welding head, so that the first welding head 501 cannot form the first welding groove, after welding by the first welding head 501, there will still be a certain interlayer gap between the multiple pole tabs 311, and then the second welding head 502 is used for secondary welding, which is beneficial to reduce the interlayer gap after welding with the first welding head 501, so as to further improve the welding quality. Of course, the first welding head 501 configured as a toothed welding head is still used to perform welding to form the first weld mark area, and then the second welding head 502 configured as a toothed welding head is used to perform welding to form the second weld mark area 502a. At this time, each original first welding groove on the second weld mark area 502a is respectively formed into a second welding groove, and / or the welding groove formed by the welding teeth of the second welding head 502 is also a second welding groove.

[0117] In some embodiments, both the first welding groove and the second welding groove are formed as stepped grooves. In this case, the second welding groove can be formed by welding the first welding groove again, or can be formed in the process of welding the second region 3122 alone.

[0118] It can be understood that the step groove can be constructed as follows: the step groove includes multiple groove portions, and the multiple groove portions are respectively the first groove portion to the pth groove portion which are arranged in sequence along the recessed direction of the step groove, the qth groove portion is arranged on the bottom wall of the (q-1)th groove portion, and the bottom wall of the (q-1)th groove portion is arranged beyond the qth groove portion, 2≤q≤p, p and q are both positive integers; it can be seen that for the multiple groove portions, in any two adjacent groove portions, the qth groove portion is arranged on the side wall of the (q-1)th groove portion opposite to its groove opening (that is, the bottom wall of the (q-1)th groove portion), and the qth groove portion occupies a part of the bottom wall of the (q-1)th groove portion, so that the bottom wall of the (q-1)th groove portion exceeds the qth groove portion in a direction perpendicular to the groove direction of the step groove.

[0119] In the above technical solution, since the first welding groove and the second welding groove are both formed as stepped grooves, for any two adjacent groove portions, the portion of the bottom wall of the qth groove portion that exceeds the (q-1)th groove portion corresponding to the multiple pole tabs 311 can be pressed and compacted during welding; during the welding process, the structure corresponding to the pth groove portion on the welding device 500 contacts the pole tab 311 before other portions, so as to achieve pre-pressing and shaping of the local areas of the multiple pole tabs 311, so as to reduce the gaps between the multiple pole tabs 311, and the above-mentioned structure corresponding to the pth groove portion on the welding device 500 can pre-press and shape the multiple pole tabs The sheet 311 is compacted and pressed; as the welding device 500 continues to apply pressure, the depth of the welding groove increases, and the bottom wall of each groove portion from the (p-1)th groove portion to the first groove portion that exceeds the corresponding groove portion can be formed by multiple pre-pressing and shaping by the welding device 500 to further reduce the gap between the multiple pole tab sheets 311, so that the multiple pole tab sheets 311 are subjected to multi-layer pressing and multi-layer compaction by the welding device 500 during the welding process, and the multiple pole tab sheets 311 are not penetrated, thereby improving the problem of excessive intervals between the multi-layer foil pieces during the welding process, and facilitating improving the welding quality and welding stability.

[0120] For example, p=2, then the multiple groove portions are respectively the first groove portion and the second groove portion which are arranged in sequence along the recessed direction of the step groove, and the second groove portion is arranged on the bottom wall of the first groove portion; the bottom wall of the first groove portion is arranged beyond the second groove portion, then along the thickness direction of the pole ear portion 31, the orthographic projection of the second groove portion is located within the range of the orthographic projection outer contour of the bottom wall of the first groove portion, so that a part of the orthographic projection of the bottom wall of the first groove portion exceeds the orthographic projection outer contour of the second groove portion.

[0121] For another example, p=3, then the multiple groove portions are respectively the first groove portion, the second groove portion and the third groove portion which are arranged in sequence along the recessed direction of the step groove, the second groove portion is arranged on the bottom wall of the first groove portion, and the bottom wall of the first groove portion is arranged beyond the second groove portion, then along the thickness direction of the pole ear portion 31, the orthographic projection of the second groove portion is located within the orthographic projection outer contour range of the bottom wall of the first groove portion, so that a part of the orthographic projection of the bottom wall of the first groove portion exceeds the orthographic projection outer contour of the second groove portion; the third groove portion is arranged on the bottom wall of the second groove portion, and the bottom wall of the second groove portion is arranged beyond the third groove portion, then along the thickness direction of the pole ear portion 31, the orthographic projection of the third groove portion is located within the orthographic projection outer contour range of the bottom wall of the second groove portion, so that a part of the orthographic projection of the bottom wall of the second groove portion exceeds the orthographic projection outer contour of the third groove portion.

[0122] For another example, p=4, then the plurality of groove portions are respectively the first groove portion, the second groove portion, the third groove portion and the fourth groove portion which are sequentially arranged along the concave direction of the step groove, the second groove portion is arranged at the bottom wall of the first groove portion, and the bottom wall of the first groove portion is arranged beyond the second groove portion, then along the thickness direction of the pole ear portion 31, the orthographic projection of the second groove portion is located within the orthographic projection outer contour range of the bottom wall of the first groove portion, so that a part of the orthographic projection of the bottom wall of the first groove portion exceeds the orthographic projection outer contour of the second groove portion; the third groove portion is arranged at the bottom wall of the second groove portion, and the bottom wall of the second groove portion exceeds the third groove portion. The third groove is provided, and along the thickness direction of the pole ear portion 31, the orthographic projection of the third groove portion is located within the orthographic projection outer contour range of the bottom wall of the second groove portion, so that a part of the orthographic projection of the bottom wall of the second groove portion exceeds the orthographic projection outer contour of the third groove portion; the fourth groove portion is provided on the bottom wall of the third groove portion, and the bottom wall of the third groove portion exceeds the orthographic projection outer contour of the fourth groove portion. Of course, for the pole ear portion 31, p can also be greater than or equal to 5.

[0123] For example, in combination Fig.18 and Fig.19 First, a first welding head 501 (e.g., Fig. 9 As shown in FIG. 1 , a plurality of tab sheets 311 are welded to form a first weld mark area 501a, and then a second welding head 502 (for example, as shown in FIG. 1 ) configured as a toothless welding head is used. Fig.14 and Fig.15 As shown in the figure, at least a portion of the first weld print area 501a is welded again to form a second weld print area 502a, and the welding teeth on the first welding head 501 can be configured as stepped teeth 503.

[0124] In some embodiments, the second region 3122 is further formed with a third welding groove, and the third welding groove is located between two adjacent second welding grooves; for example, the arrangement and shape of the plurality of second welding grooves are the same as those of the plurality of first welding grooves, and a third welding groove is provided between two adjacent second welding grooves, and the depth of the third welding groove may also be less than the depth of the first welding groove. It can be seen that the third welding groove and the first welding groove can be formed in different welding processes, respectively, and the third welding groove and the second welding groove are staggered, so that the welding device 500 can press and compact the local area between two adjacent second welding grooves in the second region 3122, which is conducive to improving the compaction area of ​​the welding device 500 for the plurality of pole tabs 311, and is conducive to further reducing the interlayer gap between the plurality of pole tabs 311 and improving the welding quality without substantially increasing the size of the welding head.

[0125] In the embodiment of the present application, the relative size of the depth of the third welding groove and the depth of the second welding groove is not specifically limited. Optionally, the third welding groove can be formed by processing the fourth welding tooth on the second welding head 502, in which case the second welding head 502 can have the second welding tooth 5022 and the fourth welding tooth, and the fourth welding tooth is arranged between two adjacent second welding teeth; or, the third welding groove can be formed by processing the second welding tooth 5022 on the second welding head 502, in which case when the second welding head 502 welds the second area 3122, the first welding groove of the second area 3122 is formed into the second welding groove after the depth is reduced, and the second welding head 502 may not need to be provided with the fourth welding tooth; or, the third welding groove can also be formed by the depth of part of the first welding groove being reduced during the welding process of the second welding head 502, in which case the first welding head 501 can have the first welding tooth 5012 and the fifth welding tooth, and the fifth welding tooth is arranged between two adjacent first welding teeth 5012, for example, the protruding height of the fifth welding tooth is less than the protruding height of the first welding tooth 5012.

[0126] In some embodiments, the third welding groove is formed as a stepped groove. Therefore, during the welding process, the local area between two adjacent second welding grooves in the second area 3122 can be pressed and compacted in multiple layers, which is beneficial to further reduce the interlayer gap and facilitate further improving the welding quality.

[0127] In some embodiments, the gathering portion 312 further includes a third region, the third region is arranged around the first region 3121, and a plurality of fourth welding grooves are formed in the third region, the plurality of fourth welding grooves are located at the edge of the first region 3121, and the plurality of fourth welding grooves are located at the periphery of the plurality of first welding grooves. Thus, by arranging a plurality of fourth welding grooves at the edge of the first region 3121, the welding device 500 can perform a certain pre-compression shaping on the plurality of pole tabs 311 at the position corresponding to the fourth welding groove, i.e., the edge of the first region 3121. At the same time, since the welding device 500 optimizes the friction region between the pole tab 311 and the pole tab 311 as local surface friction, it is beneficial to reduce the local stress concentration of the pole tab 311, and further improve the cracking of the pole tab 311.

[0128] The depth of the fourth welding groove may be less than the depth of the first welding groove, so that the welding device 500 can achieve a suitable pre-stressing and shaping effect on the pole tab 311 while improving the cracking of the pole tab 311 .

[0129] Optionally, the shape of the fourth welding groove is different from that of the first welding groove; and / or, the depth of the fourth welding groove may be greater than the depth of the first groove portion of the stepped groove, so as to achieve a suitable pre-stressing and shaping effect on the pole tab 311 .

[0130] In a second aspect, an embodiment of the present application provides a battery 200 including the above-mentioned battery cell 100 .

[0131] In the above technical solution, since the battery 200 adopts the above battery cell 100 and the reliability of the battery cell 100 is improved, the reliability of the battery 200 can be improved.

[0132] In a third aspect, an embodiment of the present application provides an electrical device 1000, comprising the above-mentioned battery 200, and the battery 200 is used to provide electrical energy.

[0133] In the above technical solution, since the power-consuming device 1000 adopts the above-mentioned battery 200 and the reliability of the battery 200 is improved, it is beneficial to improve the working performance of the power-consuming device 1000.

[0134] In a fourth aspect, an embodiment of the present application provides a welding device 500, which is used to process the above-mentioned battery cell 100, and the welding device 500 includes a first welding head 501 and a second welding head 502, the first welding head 501 is used to weld multiple pole tabs 311 to form a first weld print area 501a, and the second welding head 502 is used to weld at least part of the first weld print area 501a to form a second weld print area 502a, the intersection of the second weld print area 502a and the first weld print area 501a corresponds to the second area 3122, and the part of the first weld print area 501a other than the second weld print area 502a includes the first area 3121, then the part of the first weld print area 501a other than the second weld print area 502a can be the first area 3121, or, the part of the first weld print area 501a other than the second weld print area 502a can include not only the first area 3121 but also other areas other than the first area 3121 and the second area 3122. Obviously, the first weld mark area 501a is formed by the first welding head 501 , and the second weld mark area 502a is formed by the second welding head 502 .

[0135] Exemplarily, the second welding head 502 welds part of the first weld print area 501a to form the second weld print area 502a, and the intersection of the second weld print area 502a and the first weld print area 501a is the second weld print area 502a; or, the second welding head 502 not only welds part of the first weld print area 501a, but also welds other areas, and the intersection of the second weld print area 502a and the first weld print area 501a is a part of the second weld print area 502a.

[0136] It can be seen that the welding device 500 can perform at least two weldings on the multiple pole tabs 311 to form the first area 3121 and the second area 3122 respectively, the number of welding times to form the second area 3122 is greater than the number of welding times to form the first area 3121, and the welding process corresponding to the second area 3122 and the welding process corresponding to the first area 3121 overlap at least one welding process, so that the thickness of the multiple pole tabs 311 in the first area 3121 and the thickness of the second area 3122 are both smaller than the stacking thickness of the multiple pole tabs 311 in the pole tab portion 31, and the compaction degree of the multiple pole tabs 311 in the second area 3122 is greater than the compaction degree in the first area 3121, which is beneficial to saving the welding process of the multiple pole tabs 311 while improving the welding quality at the connecting portion 313, facilitating the simplification of the processing process of the battery cell 100 and improving the processing efficiency.

[0137] For example, after a plurality of pole tabs 311 are stacked, the first welding head 501 is used to weld the plurality of pole tabs 311 for the first welding. At this time, the thickness of the first weld print area 501a can be less than the stacking thickness of the plurality of pole tabs 311 of the pole tab portion 31. The second welding head 502 is used to weld at least a portion of the first weld print area 501a to form a second weld print area 502a. The thickness corresponding to the intersection of the first weld print area 501a and the second weld print area 502a is less than the thickness of other areas of the first weld print area 501a, so that the compaction degree of the second area 3122 is greater than the compaction degree of the first area 3121. Of course, in other embodiments of the present application, after a plurality of pole tabs 311 are stacked, the first welding head 501 is used for the mth welding, where m≥2 and is a positive integer.

[0138] It can be understood that the welding process corresponding to the second welding head 502 is located after the welding process corresponding to the first welding head 501. In the multiple welding of multiple pole tabs 311 to form the gathered portion 312, the welding process corresponding to the first welding head 501 and the welding process corresponding to the second welding head 502 can be two of the above-mentioned multiple welding processes. The two welding processes can be adjacent or there can be at least one other welding process.

[0139] Optionally, in multiple welding processes performed on multiple pole tabs 311 , the weld mark areas corresponding to any two adjacent welding processes have an intersection, so that the second area 3122 is formed as the area with the greatest degree of compaction on the gathered portion 312 .

[0140] Among them, please refer to Figure 8-Figure 11The first welding head 501 and the second welding head 502 are both toothed welding heads. The first welding head 501 includes a first body 5011 and a first welding tooth 5012. There are multiple first welding teeth 5012, and the multiple first welding teeth 5012 are arranged at intervals. The multiple first welding teeth 5012 are protruded on the welding surface R of the first body 5011. The second welding head 502 includes a second body 5021 and a second welding tooth 5022. There are multiple second welding teeth 5022, and the multiple second welding teeth 5022 are arranged at intervals. The multiple second welding teeth 5022 are protruded on the welding surface R of the second body 5021; the protruding height of the second welding tooth 5022 is less than the protruding height of the first welding tooth 5012.

[0141] Thus, when the first welding head 501 welds the plurality of pole tabs 311, the first welding teeth 5012 contact the pole tabs 311 before the welding surface R of the first body 5011, so that the pre-pressing and shaping of the local area of ​​the plurality of pole tabs 311 can be achieved, which is beneficial to reducing the interlayer gaps of the plurality of pole tabs 311 in the first weld print area. During the welding process, the second welding head 502 can press and compact the multi-layer pole tabs 311 through the second welding teeth 5022 to improve the problem that the interlayer gaps of the multi-layer pole tabs 311 are still large after at least one welding, so as to improve the welding quality and welding stability.

[0142] Exemplarily, when the first welding head 501 has a first welding tooth 5012 and the second welding head 502 has a second welding tooth 5022, the first welding tooth 5012 can form a first welding groove on the first area 3121 and the second area 3122, respectively, the first welding groove on the second area 3122 forms a second welding groove in a subsequent welding process, and / or the second welding tooth 5022 can form a second welding groove on the second area 3122.

[0143] In the embodiment of the present application, there is no specific limitation on the arrangement of the plurality of first welding teeth 5012 and the arrangement of the plurality of first welding grooves. It can be understood that all the first welding teeth 5012 can be used to form a plurality of first welding grooves on the first area 3121; or, a portion of the first welding teeth 5012 are used to form a plurality of first welding grooves on the first area 3121, and the remaining first welding teeth 5012 are used to form a plurality of first welding grooves on the second area 3122, and the first welding grooves on the second area 3122 can form second welding grooves after subsequent welding.

[0144] In some embodiments, the first welding tooth 5012 is formed as a stepped tooth 503 .

[0145] It can be understood that the step tooth 503 can be constructed as follows: the step tooth 503 includes a plurality of tooth portions 503a, the plurality of tooth portions 503a are respectively the first tooth portion to the pth tooth portion sequentially arranged along the protruding direction of the step tooth 503, the qth tooth portion is arranged at an end face of the (q-1)th tooth portion away from the welding surface R, and the end face of the (q-1)th tooth portion away from the welding surface R exceeds the qth tooth portion, 2≤q≤p, p and q are both positive integers; it can be seen that for the plurality of tooth portions 503a, among any two adjacent tooth portions 503a, the tooth portion 503a away from the welding surface R is arranged at an end of the tooth portion 503a close to the welding surface R away from the welding surface R, and the end face of the tooth portion 503a close to the welding surface R away from the welding surface R exceeds the tooth portion 503a away from the welding surface R, that is, the end face of the (q-1)th tooth portion away from the welding surface R exceeds the qth tooth portion in a direction perpendicular to the protruding direction of the step tooth 503.

[0146] It can be seen that for any two adjacent teeth 503a, the end surface of the (q-1)th tooth away from the welding surface R exceeds the part of the qth tooth, which can be formed into a welding pressure surface; during the welding process, the pth tooth contacts the welding material before other teeth 503a, so as to realize the pre-pressing and shaping of the local area of ​​the welding material, so as to reduce the gap between the multi-layer foil materials of the welding material, and the pth tooth can compact and pressure the multi-layer foil materials; as the first welding head 501 continues to apply pressure, the (p-1)th tooth until the first tooth It contacts the welding material in sequence to achieve multiple pre-pressing and shaping of the welding material area to be welded, so as to further reduce the gap between the multiple layers of foil. At the same time, the welding pressing surface from the (p-1)th tooth portion to the first tooth portion can compact and press the multiple layers of pole tab sheet 311 in sequence, so that the first welding head 501 can perform multiple layer pressing on the multiple layers of pole tab sheet 311 through the first welding tooth 5012 during the welding process, so as to effectively improve the problem of excessive gap between the multiple layers of pole tab sheet 311 during the welding process, so as to improve the welding quality and welding stability.

[0147] Obviously, the outer surface of the pth tooth portion can be formed as a welding pressing surface; and, since the first weld tooth 5012 can perform multi-layer pressing on the weld material during the welding process, so as to simultaneously take into account that the first weld tooth 5012 will not penetrate the weld material during the welding process, thereby improving the penetration ability of the first weld tooth 5012 in its protruding direction while not excessively increasing the penetration ability of the first weld tooth 5012, so as to improve the welding reliability.

[0148] In the above technical solution, since the first welding tooth 5012 is formed as a stepped tooth 503, when the first welding head 501 welds the multi-layer pole ear sheet 311, each tooth portion 503a can compact and press the multi-layer pole ear sheet 311 to achieve multi-layer pressing and compacting of the welding material, effectively reducing the interlayer gap between the multi-layer pole ear sheets 311, thereby reducing the welding energy loss caused by the excessive interlayer gap between the multi-layer pole ear sheets 311. At the same time, the first welding tooth 5012 will not penetrate the multi-layer pole ear sheet 311, thereby improving the welding quality and welding efficiency.

[0149] Exemplarily, the first welding head 501 is an ultrasonic welding head, so that the first welding head 501 is used for ultrasonic welding of multiple pole tabs 311. Since the ultrasonic welding head of the embodiment of the present application can reduce the gap between the multiple pole tabs 311, it can reduce the welding energy loss caused by the excessive interlayer gap between the multiple pole tabs 311, improve the welding energy utilization rate, and thus improve the ultrasonic welding efficiency. In addition, the second welding head 502 will subsequently weld part of the first weld print area 501a, so that the intersection of the first weld print area 501a and the second weld print area 502a is the second area 3122. Then, the second welding head 502 further reduces or even eliminates the interlayer gap of the above-mentioned part of the first weld print area 501a, so that the multiple pole tabs 311 are formed into a dense plate-like structure in the second area 3122, so that when the connecting portion 313 is laser welded with the pole 2 / adapter 4, crack-free and reliable welding of the pole tab portion 31 and the pole 2 / adapter 4 can be achieved.

[0150] For example, any tooth portion 503a of the stepped tooth 503 may be formed into any one of a prism structure, a truncated cone structure, and a spherical structure, and the shapes of the plurality of tooth portions 503a of the stepped tooth 503 may be the same or different. Of course, the shape of the first welding tooth 5012 is not limited thereto, for example, the entire first welding tooth 5012 may be formed into a prism structure, a truncated cone structure, or a spherical structure.

[0151] For example, p=2, then the multiple tooth portions 503a are respectively the first tooth portion and the second tooth portion arranged in sequence along the protruding direction of the first welding tooth 5012, and the second tooth portion is arranged at an end surface of the first tooth portion away from the welding surface R; the end surface of the first tooth portion away from the welding surface R exceeds the second tooth portion, then on the welding surface R, the orthographic projection of the second tooth portion is located within the range of the orthographic projection outer contour of the end surface of the first tooth portion away from the welding surface R, so that a part of the orthographic projection of the end surface of the first tooth portion away from the welding surface R exceeds the orthographic projection outer contour of the second tooth portion.

[0152] For another example, p=3, then the multiple tooth portions 503a are respectively the first tooth portion, the second tooth portion and the third tooth portion which are arranged in sequence along the protruding direction of the first welding tooth 5012, the second tooth portion is arranged at an end face of the first tooth portion away from the welding surface R, and the end face of the first tooth portion away from the welding surface R exceeds the second tooth portion, then on the welding surface R, the orthographic projection of the second tooth portion is located within the range of the orthographic projection outer contour of the end face of the first tooth portion away from the welding surface R, so that a part of the orthographic projection of the end face of the first tooth portion away from the welding surface R exceeds the orthographic projection outer contour of the second tooth portion; the third tooth portion is arranged at an end face of the second tooth portion away from the welding surface R, that is, the third tooth portion is arranged at an end of the second tooth portion away from the first tooth portion, and the end face of the second tooth portion away from the welding surface R exceeds the third tooth portion, then on the welding surface R, the orthographic projection of the third tooth portion is located within the range of the orthographic projection outer contour of the end face of the second tooth portion away from the welding surface R, so that a part of the orthographic projection of the end face of the second tooth portion away from the welding surface R exceeds the orthographic projection outer contour of the third tooth portion.

[0153] For another example, p=4, then the multiple tooth portions 503a are respectively the first tooth portion, the second tooth portion, the third tooth portion and the fourth tooth portion which are arranged in sequence along the protruding direction of the first welding tooth 5012, the second tooth portion is arranged at an end face of the first tooth portion away from the welding surface R, and the end face of the first tooth portion away from the welding surface R exceeds the second tooth portion, then on the welding surface R, the orthographic projection of the second tooth portion is located within the outer contour range of the orthographic projection of the end face of the first tooth portion away from the welding surface R, so that a part of the orthographic projection of the end face of the first tooth portion away from the welding surface R exceeds the outer contour of the orthographic projection of the second tooth portion; the third tooth portion is arranged at an end face of the second tooth portion away from the welding surface R, that is, the third tooth portion is arranged at an end of the second tooth portion away from the first tooth portion, and the end face of the second tooth portion away from the welding surface R If one end face exceeds the third tooth portion, then on the welding surface R, the orthographic projection of the third tooth portion is located within the orthographic projection outer contour range of the end face of the second tooth portion away from the welding surface R, so that a part of the orthographic projection of the end face of the second tooth portion away from the welding surface R exceeds the orthographic projection outer contour of the third tooth portion; the fourth tooth portion is arranged at the end face of the third tooth portion away from the welding surface R, that is, the fourth tooth portion is arranged at the end of the third tooth portion away from the second tooth portion, and the end face of the third tooth portion away from the welding surface R exceeds the fourth tooth portion, then on the welding surface R, the orthographic projection of the fourth tooth portion is located within the orthographic projection outer contour range of the end face of the third tooth portion away from the welding surface R, so that a part of the orthographic projection of the end face of the third tooth portion away from the welding surface R exceeds the orthographic projection outer contour of the fourth tooth portion. Of course, for the first welding head 501, p can also be greater than or equal to 5.

[0154] For example, Fig.10As shown, in the direction of ultrasonic vibration, the spacing between two adjacent first welding teeth 5012 is x1, and in the direction perpendicular to the direction of ultrasonic vibration, the spacing between two adjacent first welding teeth 5012 is x2, x1=x2 and both are within 0.4mm~2mm, which is conducive to improving the flow uniformity of multi-layer welding materials during ultrasonic welding. Exemplarily, x1 can be 0.4mm, 0.8mm, 1mm, 1.3mm, 1.5mm, 1.8mm, or 2mm, etc.; further, 1mm≤x1≤2mm.

[0155] Optionally, the cross-sectional shape of the first welding tooth 5012 at the location of the welding surface is a square, and the width of the square corresponding to the first welding tooth 5012 is W1, 2mm≤W1≤10mm, for example, W1 can be 2mm, 3mm, 4mm, 5mm, 6.6mm, 8mm, 9mm or 10mm, etc., and further 2.4mm≤W1≤4mm. It can be understood that W1 and the height H1 of the first welding tooth 5012 protruding from the welding surface and the spacing (x1, x2) between adjacent first welding teeth 5012 cannot be too small, so as to avoid local stress concentration of the multi-layer foil during welding, which in turn causes the tab to crack; it cannot be too large, so as to avoid the inability to effectively achieve the connection between the multi-layer foil during welding.

[0156] Please refer to Figure 12-Figure 17 In some embodiments, when the first welding head 501 is a welding head with teeth, the second welding head 502 can be formed as a welding head without teeth or a welding head with teeth.

[0157] For example, Fig.12 and Fig.13 As shown, the second welding teeth 5022 are formed into a long strip extending along the ultrasonic vibration direction, and a plurality of second welding teeth 5022 are arranged at intervals along a direction perpendicular to the ultrasonic vibration direction. The width W2 of the second welding teeth 5022, the length L2 of the second welding teeth 5022, the spacing x3 between two adjacent second welding teeth 5022, and the height H2 of the second welding teeth 5022 protruding from the welding surface respectively meet the following conditions: 4mm≤W2≤8mm, W2≤L2≤5*W2, 0.5mm≤x3≤2mm, 0.4mm≤H2≤2mm. It can be understood that W2, x3, L2 and H2 cannot be too small. If they are too small, the second welding head 502 will not be able to effectively penetrate into the deepest weld mark corresponding to the first welding head 501 during resistance welding, which may cause local high voltage and cause spattering, burning of electrodes and other undesirable phenomena; if they are too large, it will easily cause undesirable phenomena such as sticking of electrodes, increase electrode wear, and reduce the service life and service reliability of electrodes.

[0158] Furthermore, 4mm≤W2≤6mm, 10mm≤L2≤12mm, 1mm≤x3≤2mm, 1mm≤H2≤2mm.

[0159] In some embodiments, the second welding teeth 5022 are formed as stepped teeth 503. Therefore, since the second welding teeth 5022 are formed as stepped teeth 503, when the second welding head 502 welds the multi-layered pole tab sheet 311, each tooth portion 503a of the second welding teeth 5022 can compact and press the multi-layered pole tab sheet 311, so as to realize multi-layer pressing and compacting of welding materials, effectively reducing the large interlayer gaps of the multi-layered pole tab sheet 311 after welding, and at the same time, the second welding teeth 5022 will not penetrate the multi-layered pole tab sheet 311, thereby improving welding quality and welding efficiency.

[0160] Please refer to Figure 9-11 In some embodiments, the first welding head 501 further includes a plurality of third welding teeth 5013 arranged at intervals, the plurality of third welding teeth 5013 are protruded on the welding surface R of the first body 5011, and the plurality of third welding teeth 5013 are arranged on the periphery of the plurality of first welding teeth 5012, and the height of the third welding teeth 5013 protruding from the welding surface R is less than the height of the first welding teeth 5012 protruding from the welding surface R. Therefore, the provision of the third welding tooth 5013 is conducive to increasing the compaction area of ​​the multi-layer pole tab sheet 311 by the first welding head 501, and increasing the number of local areas where the multi-layer pole tab sheet 311 is compacted by the first welding head 501, which is conducive to further improving the quality of ultrasonic welding; at the same time, the third welding tooth 5013 can perform a certain pre-stressing and shaping on the edge portion of the first area 3121, so as to realize the early pre-stressing and shaping of the multi-layer pole tab sheet 311, and the third welding tooth 5013 can optimize the friction area between the pole tab sheet 311 and the first welding head 501 from large-surface friction to local surface friction, thereby reducing the local stress concentration of the pole tab sheet 311, and further improving the cracking of the pole tab sheet 311.

[0161] It can be understood that when the first welding head 501 is used to perform the first welding on the multi-layer pole ear sheet 311, a portion of the multi-layer pole ear sheet 311 will be lifted up and tend to adhere to the first main body 5011. If the pole ear sheet 311 adheres to the first main body 5011, it will easily cause the pole ear sheet 311 to tear, and the gap between the layers of the multi-layer pole ear sheet 311 will be larger. The third welding tooth 5013 of the embodiment of the present application can reduce the mechanical friction applied by the high-frequency vibrating first main body 5011 to the multi-layer pole ear sheet 311 during the welding process, thereby improving stress concentration and reducing the risk of cracking of the pole ear sheet 311.

[0162] Optionally, the third welding tooth 5013 is a spherical structure, so that the outer surface of the third welding tooth 5013 has no sharp corners, thereby reducing the risk of the third welding tooth 5013 cutting the pole tab 311.

[0163] Optionally, the third welding tooth 5013 is a spherical structure, the radius of the third welding tooth 5013 is R1, the height of the first welding tooth 5012 protruding from the welding surface is H1, 0.2≤R1 / H1≤0.8, for example, R1 / H1 can be 0.2, 0.4, 0.5, 0.7, or 0.8. Thus, the third welding tooth 5013 can contact the welding material before the welding surface, so as to achieve a good pre-pressing and shaping effect. It can be understood that R1 cannot be too small to avoid local friction cracking of the edge of the weld mark during welding, and R1 cannot be too large to improve the welding effect of the first welding tooth 5012 and improve the problem of welding energy loss and causing cold welding.

[0164] Of course, the third welding tooth 5013 can also be a prism structure, a truncated cone structure, a combination of a spherical structure and a prism structure (such as a spherical structure and a square prism structure), or a combination of a spherical structure and a truncated cone structure.

[0165] Further, 0.2 mm ≤ H1 ≤ 0.6 mm, or 0.6 mm ≤ H1 ≤ 1.2 mm, and 0.2 mm ≤ R1 ≤ 0.4 mm. For example, H1 may be 0.2 mm, 0.26 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.47 mm, 0.5 mm, 0.52 mm, or 0.6 mm.

[0166] Please refer to Figure 9-Figure 17 In some embodiments, the first welding head 501 is an ultrasonic welding head, and the second welding head 502 is a resistance welding head. The first welding head 501 is used to achieve ultrasonic welding, and the second welding head 502 is used to achieve resistance welding. Therefore, resistance welding uses the resistance heat effect generated by the current flowing through the contact surface and the adjacent area of ​​the workpiece to heat it to a molten or plastic state to combine it. Resistance welding can reduce or eliminate the interlayer gap between the multi-layer pole tabs 311 after ultrasonic welding, further improve the compaction degree of the corresponding area, and achieve that the compaction degree of the second area 3122 is greater than that of the first area 3121.

[0167] In some embodiments, a transition surface S is provided between the welding surface R of at least one of the first welding head 501 and the second welding head 502 and its side wall, and the transition surface S is a rounded transition surface, and the radius of the transition surface S is 0.5 mm to 1.5 mm (including the endpoint values) to further improve the cracking of the foil, and at the same time, it is beneficial to control the size of the first welding head 501 and / or the second welding head 502, and it is not easy to cause waste of resources and excessive increase in costs.

[0168] In a fifth aspect, the present application embodiment provides a welding method, using the above-mentioned welding device 500 to process a plurality of tabs 311, please refer to Fig.18 and Fig.19 , welding methods include:

[0169] S10, stacking a plurality of tab sheets 311;

[0170] S20, using the first welding head 501 to weld the overlapping parts of the plurality of electrode tabs 311 to form a first weld mark area 501a;

[0171] S30, using the second welding head 502 to weld at least a portion of the first weld print area 501a to form a second weld print area 502a.

[0172] It can be understood that after the multiple pole tabs 311 are stacked, there are overlapping parts and misaligned parts in the multiple pole tabs 311. The misaligned part can be understood as the number of pole tabs 311 stacked in the region is less than the number of all pole tabs 311 of the pole tab portion 31, and the overlapping part can be understood as the number of pole tabs 311 stacked in the region is equal to the number of all pole tabs 311 of the pole tab portion 31; in other words, along the thickness direction of the pole tab portion 31, the part where the projections of the multiple pole tabs 311 completely overlap corresponds to the overlapping part, and the part where the projections of the multiple pole tabs 311 do not completely overlap corresponds to the misaligned part. The first weld print area 501a is the weld print area formed by welding with the first welding head 501, the second weld print area 502a is the weld print area formed by welding with the second welding head 502, and the intersection of the second weld print area 502a and the first weld print area 501a is the second area 3122.

[0173] In the above technical solution, the plurality of pole tabs 311 are welded multiple times by the welding device 500, so that the intersection of the first weld print area 501a formed by the first welding head 501 and the second weld print area 502a formed by the second welding head 502 forms the second area 3122, so that the second area 3122 has no or almost no interlayer gap, so that the part of the gathered portion 312 corresponding to the second area 3122 can form a dense plate-like structure, which is conducive to achieving crack-free and reliable connection between the connecting portion 313 and the pole 2 / adapter 4.

[0174] Exemplarily, the second welding head 502 welds at least a portion of the first weld print area 501a to form a second weld print area 502a, then at least a portion of the first weld print area 501a forms the second weld print area 502a after being welded by the second welding head 502, and the corresponding size of the second weld print area 502a is less than or equal to the corresponding size of the first weld print area 501a, thereby improving the area where the second weld print area 502a does not overlap with the first weld print area 501a, which is prone to defects such as welding penetration and wrinkles. At the same time, the first weld print area 501a can be effectively utilized without causing an unnecessary increase in cost; taking the first welding head 501 and the second welding head 502 as an example, the length L3 and width W3 of the first welding head 501 and the length L4 and width W4 of the second welding head 502 satisfy: L4≤L3, W4≤W3. To improve welding quality and taking into account the cumulative tolerance of process assembly, the length L3 and width W3 of the first welding head 501 and the length L4 and width W4 of the second welding head 502 satisfy: 0.5*L3≤L4≤0.8*L3, 0.5*W3≤W4≤0.8*W3, L4≥W4.

[0175] Further, 40mm≤L3≤45mm, 25mm≤W3≤30mm, 20mm≤L4≤30mm, 10mm≤W4≤20mm.

[0176] Optionally, the center of the first weld print area 501a coincides with the center of the second weld print area 502a.

[0177] Please refer again Figure 3-Figure 6 , Figure 9-Figure 17 , Fig.14 , Fig.15 , Fig.18 and Fig.19 , describing a battery cell 100, a welding device 500 and a welding method according to a specific embodiment of the present application.

[0178] In the embodiment of the present application, the battery cell 100 includes a housing 1, a pole 2 and an electrode assembly 3. The electrode assembly 3 is accommodated in the housing 1 and includes a pole ear portion 31. The pole ear portion 31 includes a plurality of pole ear sheets 311. The plurality of pole ear sheets 311 are stacked and connected to form a gathered portion 312. A connection portion 313 is formed at a position of the gathered portion 312 for electrical connection with the pole 2. The gathered portion 312 includes a first region 3121 and a second region 3122 adjacent to each other. The first region 3121 surrounds the entire second region 3122. The compaction degree of the plurality of pole ear sheets 311 in the second region 3122 is greater than the compaction degree in the first region 3121. The thickness of the plurality of pole ear sheets 311 in the first region 3121 is less than the stacking thickness of the plurality of pole ear sheets 311 in the pole ear portion 31. The entire connection portion 313 falls in the second region 3122. The outer edge of the portion of the connection portion 313 on the surface of the gathered portion 312 is spaced from the outer edge of the second region 3122.

[0179] The welding device 500 includes a first welding head 501 and a second welding head 502. The first welding head 501 is used to weld a plurality of pole tabs 311 to form a first weld print area 501a. The second welding head 502 is used to weld at least a portion of the first weld print area 501a to form a second weld print area 502a. The intersection of the second weld print area 502a and the first weld print area 501a corresponds to the second area 3122. The portion of the first weld print area 501a other than the second weld print area 502a is the first area 3121. During the welding process, the plurality of pole tabs 311 are stacked and arranged; the first welding head 501 is first used to weld the overlapping portions of the plurality of pole tabs 311 to form the first weld print area 501a; and the second welding head 502 is then used to weld a portion of the first weld print area 501a to form the second weld print area 502a.

[0180] Among them, the first welding head 501 is an ultrasonic welding head, and the second welding head 502 is a resistance welding head. After two weldings, the multiple pole tabs 311 form a gathered portion 312. The first welding head 501 is used to ultrasonically weld the multiple pole tabs 311 to form a first weld mark area 501a (which can be understood as an ultrasonic welding area). The second welding head 502 is used to resistance weld part of the first weld mark area 501a to form a second weld mark area 502a (which can be understood as a resistance welding area). The second weld mark area 502a completely falls within the first weld mark area 501a, and the second weld mark area 502a is spaced apart from the outer edge of the first weld mark area 501a. At this time, the second weld mark area 502a is the second area 3122, and the second area 3122 is the area with the highest degree of compaction in the gathered portion 312.

[0181] The first welding head 501 is a toothed welding head and includes a first body 5011 and a first welding tooth 5012. The first welding tooth 5012 can form a first welding groove on the first welding print area 501a. The second welding head 502 is a toothless welding head. The second welding head can make the first welding groove on the second welding print area 502a form a second welding groove.

[0182] In the above technical solution, resistance welding utilizes the resistance heat effect generated by the current flowing through the contact surface of the workpiece and the adjacent area to heat it to a molten or plastic state so that it can be combined. Resistance welding can reduce or eliminate the interlayer gap between the multilayer pole tabs 311 after ultrasonic welding, further improve the compaction degree of the corresponding area, and achieve that the compaction degree of the second area 3122 is greater than that of the first area 3121.

[0183] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0184] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, It is characterized in that include: case; A pole, arranged on the housing; An electrode assembly, housed in the housing and comprising a pole ear portion, wherein the pole ear portion comprises a plurality of pole ear sheets, wherein the plurality of pole ear sheets are stacked and connected to form a gathered portion, wherein a connection portion is formed at a position of the gathered portion for electrical connection with the pole; Wherein, the gathering portion includes an adjacent first area and a second area, the degree of compaction of the plurality of pole tabs in the second area is greater than the degree of compaction in the first area, the thickness of the plurality of pole tabs in the first area is less than the stacking thickness of the plurality of pole tabs in the pole tab portion, the stacking thickness of the plurality of pole tabs refers to the sum of the thicknesses of the plurality of pole tabs stacked without gaps before connection, at least most of the connecting portion falls in the second area, the first area is formed with a plurality of first welding grooves arranged at intervals, the second area is formed with a plurality of second welding grooves arranged at intervals, the depth of the second welding groove is less than the depth of the first welding groove, and the first welding groove and the second welding groove are suitable for corresponding to welding teeth on a welding device.

2. The battery cell according to claim 1, It is characterized in that The connecting portion is located in the second region, and an outer edge of a portion of the connecting portion on the surface of the gathering portion is spaced apart from an edge of the second region.

3. The battery cell according to claim 1, It is characterized in that The second welding grooves are the same as the first welding grooves in shape and arrangement.

4. The battery cell according to claim 1, It is characterized in that The first welding groove and the second welding groove are both formed as stepped grooves.

5. The battery cell according to claim 1, It is characterized in that A third welding groove is further formed in the second region, and the third welding groove is located between two adjacent second welding grooves.

6. The battery cell according to claim 5, It is characterized in that The third welding groove is formed as a stepped groove.

7. The battery cell according to claim 3, It is characterized in that The gathering portion also includes a third area, which is arranged around the first area, and the third area is formed with a plurality of fourth welding grooves arranged at intervals. The plurality of fourth welding grooves are located at the edge of the first area and at the periphery of the plurality of first welding grooves, and the depth of the fourth welding grooves is less than the depth of the first welding grooves.

8. The battery cell according to any one of claims 1 to 7, It is characterized in that The gathered portion is directly welded to the pole; or, The battery cell further includes a transfer plate, the folded portion is indirectly connected to the pole via the transfer plate, and the folded portion is directly welded to the transfer plate.

9. A battery, It is characterized in that The invention comprises a battery cell according to any one of claims 1 to 8.

10. An electrical device, It is characterized in that Comprising a battery according to claim 9.

11. A welding device, It is characterized in that The welding device is used for processing a battery cell according to any one of claims 1 to 8, and the welding device comprises a first welding head and a second welding head, the first welding head is used for welding a plurality of the electrode tabs to form a first weld print area, the second welding head is used for welding at least part of the first weld print area to form a second weld print area, the intersection of the second weld print area and the first weld print area corresponds to the second area, and the part of the first weld print area other than the second weld print area includes the first area, The first welding head and the second welding head are both toothed welding heads. The first welding head includes a first body and a first welding tooth. The first welding tooth is multiple and arranged at intervals. The multiple first welding teeth are convexly arranged on the welding surface of the first body. The second welding head includes a second body and a second welding tooth. The second welding tooth is multiple and arranged at intervals. The multiple second welding teeth are convexly arranged on the welding surface of the second body. The protruding height of the second welding tooth is smaller than the protruding height of the first welding tooth.

12. The welding device according to claim 11, It is characterized in that The first welding teeth are formed as stepped teeth.

13. The welding device according to claim 11, It is characterized in that The second welding teeth are formed as stepped teeth.

14. The welding device according to claim 11, It is characterized in that The first welding head also includes a plurality of third welding teeth arranged at intervals, wherein the plurality of third welding teeth are protruded on the welding surface of the first body and are arranged on the periphery of the plurality of first welding teeth, and the height of the third welding teeth protruding from the welding surface is less than the height of the first welding teeth protruding from the welding surface.

15. The welding device according to any one of claims 11 to 14, It is characterized in that The first welding head is an ultrasonic welding head, and the second welding head is a resistance welding head.

16. A welding method, It is characterized in that A plurality of tab sheets are processed using a welding device according to any one of claims 11 to 15, the welding method comprising: Stacking a plurality of the tab sheets; Using the first welding head to weld the overlapping parts of the plurality of electrode tabs to form a first weld mark area; The second welding head is used to weld at least a portion of the first weld print area to form a second weld print area.

Images