Battery cell, battery, and electric device

Abstract

This application discloses a battery cell, a battery, and an electrical device. The battery cell includes a casing, electrode terminals, an electrode assembly, and a connecting piece. The electrode terminals are disposed in the casing. The electrode assembly is housed within the casing. The electrode assembly includes a main body and a tab, with the tab extending from the end of the main body facing the electrode terminal. The connecting piece is welded to the tab to form a first weld portion, and the connecting piece, the tab, and the electrode terminal are welded to form a second weld portion. Through the first and second weld portions, multiple conductive paths can be formed between the tab and the electrode terminal, thereby improving the current carrying capacity between the tab and the electrode terminal and reducing heat generation.

Description

Battery cell, battery and electric device

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202420723956.3, filed on April 9, 2024, entitled “Battery cell, battery and electric device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of batteries, in particular to a battery cell, a battery and an electric device. BACKGROUND

[0004] Battery cells are widely used in electronic devices, such as mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes and electric tools, etc.

[0005] How to improve the reliability of battery cells is a research direction in battery technology.

[0006] Practical new type content

[0007] The present application provides a battery cell, a battery and an electric device, which can improve the reliability of the battery cell.

[0008] In a first aspect, the present application provides a battery cell, which includes a shell, an electrode terminal, an electrode assembly and a connecting piece. The electrode terminal is arranged in the shell. The electrode assembly is accommodated in the shell. The electrode assembly includes a main body part and a tab, and the tab extends from one end of the main body part facing the electrode terminal. The connecting piece is welded with the tab and forms a first welding part, and the connecting piece, the tab and the electrode terminal are welded and form a second welding part.

[0009] Through the first welding part and the second welding part, a plurality of conductive paths can be formed between the tab and the electrode terminal, thereby improving the overcurrent capacity between the tab and the electrode terminal and reducing heat generation. Compared with the second welding part, the formation of the first welding part is irrelevant to the electrode terminal, the first welding part has less impact on the tab, and the part of the tab close to the first welding part is less likely to tear; when the battery cell is subjected to external impact, even if the part of the tab close to the second welding part tears, the current can be conducted to the electrode terminal via the first welding part, the connecting piece and the second welding part, thereby reducing the risk of connection failure of the tab and the electrode terminal and improving the reliability of the battery cell.

[0010] In some embodiments, the first welding part is directly connected with the second welding part. During the working process of the battery cell, the current can be directly transmitted between the first welding part and the second welding part, thereby shortening the conductive path, reducing the resistance, improving the overcurrent capacity and reducing the heat generation.

[0011] In some embodiments, at least part of the first welding portion is arranged around the second welding portion, which can reduce the difference in distance between different parts of the first welding portion and the second welding portion, improve the uniformity of current flow, and reduce heat generation.

[0012] In some embodiments, the outer periphery of the second welding portion is directly connected with the first welding portion, which can increase the current flow area between the first welding portion and the second welding portion, reduce the resistance, shorten the conduction path, improve the current flow capacity, and reduce heat generation.

[0013] In some embodiments, at least part of the connecting piece is located between the electrode terminal and the tab in the thickness direction of the connecting piece, and is welded with the tab and the electrode terminal, respectively. Arranging the connecting piece between the tab and the electrode terminal can reduce the risk of interference between the connecting piece and the tab during the bending of the tab.

[0014] In some embodiments, the tab includes a laminated section and a bent section, the laminated section is attached to the connecting piece in the thickness direction, and the bent section is bent from one end of the laminated section and connected to the main body portion. The laminated section is welded to the connecting piece and forms the first welding portion, and the connecting piece, the laminated section, and the electrode terminal are welded and form the second welding portion. By bending the tab, the space occupied by the tab in the thickness direction can be reduced, and the space utilization rate can be improved.

[0015] In some embodiments, in the thickness direction, part of the connecting piece does not overlap with the laminated section. The connecting piece has a large size, which can reduce the risk of false welding and improve the connection strength when welding the connecting piece and the laminated section; in addition, part of the connecting piece can not be blocked by the laminated section when welding the laminated section, the connecting piece and the electrode terminal, so as to facilitate the positioning of the connecting piece, improve the welding precision, and reduce the risk of false welding.

[0016] In some embodiments, the laminated section includes a first edge and two second edges, the first edge is located at one end of the laminated section away from the bent section, and the two second edges are oppositely arranged and connected to the first edge. Part of the connecting piece exceeds the first edge; in the arrangement direction of the two second edges, both of the two second edges exceed the connecting piece.

[0017] When welding the tab, the connecting piece and the electrode terminal, the part of the connecting piece exceeding the first edge can be used for positioning, so as to improve the welding precision and reduce the risk of false welding. In the arrangement direction of the two second edges, the connecting piece can have a size smaller than that of the laminated section, so as to save space and improve the energy density.

[0018] In some embodiments, the electrode terminal has an inner surface facing the connecting piece, and the inner surface is in contact with the connecting piece in the thickness direction. The stacked section includes two second edges arranged opposite each other; in the arrangement direction of the two second edges, both ends of the connecting piece extend beyond the inner surface, and both second edges extend beyond the connecting piece. The connecting piece can cover the electrode terminal as much as possible, thereby reducing the risk of cold welding and increasing the contact area and connection strength between the connecting piece and the electrode terminal. In the arrangement direction of the two second edges, the portion of the connecting piece that extends beyond the electrode terminal will not be connected to the electrode terminal. Therefore, the connecting piece can have a size smaller than the stacked section, thereby saving space and improving energy density.

[0019] In some embodiments, in the extension direction of the tab, at least a portion of the first welding portion is located between the root of the tab and the second welding portion. The embodiments of the present application can shorten the conductive path, reduce heat generation, and improve current carrying capacity.

[0020] In some embodiments, in the thickness direction of the connecting sheet, the projected area of ​​the first welding portion is greater than or equal to 0.2 times the projected area of ​​the second welding portion, so as to improve the current flow capacity between the tab and the electrode terminal, reduce the risk of connection failure between the tab and the electrode terminal, and improve the reliability of the battery cell.

[0021] In some embodiments, the tab and the electrode terminal are connected by ultrasonic welding to form a first weld, and the tab, the electrode terminal, and the electrode terminal are connected by laser welding to form a second weld. Ultrasonic welding minimizes the thermal impact on the tab, and after welding, the portion of the tab near the first weld is less susceptible to tearing. Laser welding can reduce welding difficulty and increase the strength of the second weld.

[0022] In some embodiments, the thickness of the connecting sheet is 0.1 mm to 1.5 mm. Limiting the thickness of the connecting sheet to greater than or equal to 0.1 mm can improve the strength of the connecting sheet and reduce the risk of the connecting sheet tearing; limiting the thickness of the connecting sheet to less than or equal to 1.5 mm can reduce the difficulty of welding, reduce welding heat generation, reduce thermal stress on the tab, and reduce the risk of tab tearing.

[0023] In a second aspect, the present application provides a battery comprising a plurality of battery cells provided according to any embodiment of the first aspect.

[0024] In a third aspect, the present application provides an electrical device, comprising a battery provided according to any embodiment of the second aspect, wherein the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0026] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application;

[0027] FIG. 2 is an exploded schematic diagram of a battery according to some embodiments of the present application;

[0028] FIG. 3 is a structural schematic diagram of a battery cell according to some embodiments of the present application;

[0029] FIG. 4 is a sectional schematic diagram of a battery cell according to some embodiments of the present application;

[0030] FIG. 5 is another sectional schematic diagram of a battery cell according to some embodiments of the present application;

[0031] FIG. 6 is an enlarged schematic diagram of the circle frame in FIG. 4;

[0032] FIG. 7 is an enlarged schematic diagram of the square frame in FIG. 5;

[0033] FIG. 8 is yet another sectional schematic diagram of a battery cell according to some embodiments of the present application.

[0034] Reference signs are explained as follows: 1, vehicle; 2, battery; 3, controller; 4, motor; 5, case; 5a, first case portion; 5b, second case portion; 5c, accommodation space; 6, battery cell; 10, electrode assembly; 11, main body portion; 12, tab; 121, laminated section; 121a, first edge; 121b, second edge; 122, bent section; 123, root portion; 20, outer shell; 21, housing; 22, end cap; 30, electrode terminal; 31, inner surface; 40, connecting tab; 50, terminal plate; W1, first welding portion; W2, second welding portion; X, second direction; Y, first direction; Z, thickness direction. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and superiorities of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall into the scope of the present application.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the specification herein is for describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise defined, all terms used in disclosing the application, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The articles 'a', 'an', and 'the' each followed by'some or more' or 'one or more' of an element are intended to include one or more articles of the described element and do not exclude other additional elements. As used in this application, the terms "comprises", "comprising", "includes", "including", or the like are used in the sense of "including but not limited to", even if the phrases "one or more of", "at least", "must", "exactly", etc. are not used.

[0037] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of other embodiments.

[0038] In the description of the application, it is necessary to explain that, unless otherwise explicitly defined and limited, the terms "mounting", "connecting", "connecting", "attaching" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0039] In the application, the term "and / or" is only a description of the association relationship between the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the application generally represents an "or" relationship between the front and rear associated objects.

[0040] In the embodiments of the application, the same reference signs represent the same parts, and for the sake of brevity, the detailed description of the same parts is omitted in different embodiments. It should be understood that the thickness, length and width of various components in the embodiments of the application shown in the drawings, as well as the overall thickness, length and width of the integrated device, are only exemplary and should not constitute any limitation on the application.

[0041] "Multiple" appearing in the application means more than two (including two).

[0042] In the embodiments of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to use.

[0043] The battery cell can include, but is not limited to, a lithium ion battery cell, a sodium ion battery cell, a sodium lithium ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium sulfur battery cell, a magnesium ion battery cell, a nickel hydrogen battery cell, a nickel cadmium battery cell, a lead-acid battery cell, and the like.

[0044] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, or a battery cell of other shapes, the prismatic battery cell including a square cell, a blade cell, a multi-prismatic battery cell, for example, a hexagonal prismatic battery cell, and the like, without particular limitation.

[0045] The battery referred to in embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0046] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0047] In some embodiments, the battery can be a battery pack, and the battery pack includes a box body and battery cells, and the battery cells or battery modules are accommodated in the box body.

[0048] In some embodiments, the box body can be part of the chassis structure of the vehicle. For example, part of the box body can be at least part of the floor of the vehicle, or part of the box body can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0049] In some embodiments, the battery can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, and the like.

[0050] Generally, the battery includes an electrode assembly, a case, and an electrode terminal, the electrode assembly is accommodated in the case, and the electrode terminal is provided with the case. The electrode assembly includes a tab, and the tab is electrically connected to the electrode terminal; the electrode terminal can be used to electrically connect the electrode assembly with the circuit outside the battery cell to realize charging or discharging of the battery cell.

[0051] In the related art, the tab can be directly connected to the electrode terminal by welding, and the welding part of the tab and the electrode terminal can transmit current. However, the tab is thin, and when the battery cell is subjected to external impact, the part of the tab close to the welding part is easy to tear, thereby reducing the overcurrent capacity between the tab and the electrode terminal, increasing heat generation, and even causing the connection between the tab and the electrode terminal to fail, affecting the reliability of the battery cell.

[0052] In view of this, the embodiment of the present application provides a technical scheme, which sets a connecting piece to connect the tab and the electrode terminal, and forms a plurality of conductive paths between the tab and the electrode terminal, thereby improving the overcurrent capacity between the tab and the electrode terminal, reducing heat generation, reducing the risk of connection failure of the tab and the electrode terminal, and improving the reliability of the battery monomer.

[0053] The technical scheme described in the embodiment of the present application is applicable to a power consumption device using a battery.

[0054] The power consumption device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, and an electric tool, etc. The vehicle can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile, or a range extended automobile, etc. The spacecraft includes an airplane, a rocket, a space shuttle, and a spacecraft, etc. The electric toy includes a fixed or mobile electric toy, for example, a game machine, an electric automobile toy, an electric ship toy, and an electric airplane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, for example, an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, and an electric planer, etc. The embodiment of the present application does not specially limit the above power consumption device.

[0055] The following embodiments take the vehicle as an example for convenience of description.

[0056] FIG. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application.

[0057] As shown in FIG. 1, the vehicle 1 is internally provided with a battery 2, which can be arranged at the bottom, the head, or the tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1, for example, the battery 2 can be used as an operating power supply of the vehicle 1.

[0058] The vehicle 1 can further include a controller 3 and a motor 4, and the controller 3 is used to control the battery 2 to supply power to the motor 4, for example, to meet the working power demand of the vehicle 1 during starting, navigation, and driving.

[0059] In some embodiments of the present application, the battery 2 can not only be used as an operating power supply of the vehicle 1, but also be used as a driving power supply of the vehicle 1, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1.

[0060] FIG. 2 is an exploded schematic diagram of a battery provided by some embodiments of the present application.

[0061] As shown in FIG. 2, the battery 2 includes a box body 5 and a battery monomer 6, and the battery monomer 6 is contained in the box body 5.

[0062] The box 5 is used to accommodate the battery cell 6, and the box 5 can be of various structures. In some embodiments, the box 5 can include a first box part 5a and a second box part 5b, the first box part 5a and the second box part 5b are mutually covered, and the first box part 5a and the second box part 5b jointly define an accommodation space 5c for accommodating the battery cell 6. The second box part 5b can be a hollow structure with one end open, and the first box part 5a is a plate-shaped structure, which covers the open side of the second box part 5b to form the box 5 with the accommodation space 5c; or the first box part 5a and the second box part 5b can both be a hollow structure with one side open, and the open side of the first box part 5a covers the open side of the second box part 5b to form the box 5 with the accommodation space 5c. Of course, the first box part 5a and the second box part 5b can be of various shapes, such as a cylinder, a cuboid, etc.

[0063] To improve the sealing performance of the first box part 5a and the second box part 5b after being connected, a sealing member such as sealing glue, a sealing ring, etc. can be arranged between the first box part 5a and the second box part 5b.

[0064] Suppose that the first box part 5a covers the top of the second box part 5b, the first box part 5a can also be referred to as an upper box cover, and the second box part 5b can also be referred to as a lower box.

[0065] In the battery 2, the battery cell 6 can be one or multiple. If the battery cell 6 is multiple, the multiple battery cells 6 can be connected in series, in parallel, or in a mixed manner, and the mixed manner means that the multiple battery cells 6 are connected in series and in parallel. The multiple battery cells 6 can be directly connected in series, in parallel, or in a mixed manner, and then the whole of the multiple battery cells 6 is accommodated in the box 5; of course, the multiple battery cells 6 can be first connected in series, in parallel, or in a mixed manner to form a battery module, and then the multiple battery modules are connected in series, in parallel, or in a mixed manner to form a whole, which is accommodated in the box 5.

[0066] FIG. 3 is a structural schematic diagram of a battery cell provided by some embodiments of the present application; FIG. 4 is a sectional view schematic diagram of a battery cell provided by some embodiments of the present application; FIG. 5 is another sectional view schematic diagram of a battery cell provided by some embodiments of the present application; and FIG. 6 is an enlarged schematic diagram of a circle frame in FIG. 4;

[0067] FIG. 7 is an enlarged schematic diagram of a square frame in FIG. 5; and FIG. 8 is still another sectional view schematic diagram of a battery cell provided by some embodiments of the present application.

[0068] Referring to FIGS. 3 to 8, the embodiments of the present application provide a battery cell 6, which includes an outer shell 20 and an electrode assembly 10, and the electrode assembly 10 is accommodated in the outer shell 20.

[0069] The electrode assembly 10 includes a positive electrode and a negative electrode. During charging and discharging of the battery cell 6, active ions (e.g., lithium ions) are intercalated and deintercalated between the positive electrode and the negative electrode. Optionally, the electrode assembly 10 further includes a separator disposed between the positive electrode and the negative electrode, which can reduce the risk of short circuit between the positive electrode and the negative electrode while allowing the active ions to pass through.

[0070] The housing 20 is used to encapsulate the electrode assembly 10 and other components such as electrolyte. The housing 20 can be a steel shell, an aluminum shell, a plastic shell (e.g., polypropylene), a composite metal shell (e.g., a copper-aluminum composite shell), or an aluminum-plastic film, etc.

[0071] In some embodiments, the positive electrode includes a positive electrode sheet. The positive electrode sheet can include a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.

[0072] By way of example, the positive electrode current collector has two opposite surfaces in the thickness direction of itself, and the positive electrode active material layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0073] In some embodiments, the negative electrode includes a negative electrode sheet. The negative electrode sheet can include a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector.

[0074] In some embodiments, the material of the positive electrode current collector can be aluminum, and the material of the negative electrode current collector can be copper.

[0075] In some embodiments, the electrode assembly 10 further includes a separator for separating the positive electrode sheet and the negative electrode sheet. The separator can reduce the risk of short circuit between the positive electrode and the negative electrode while allowing the active ions to pass through.

[0076] In some embodiments, the separator includes a separator film. The separator film of the present application can be any known porous structure separator film with good chemical stability and mechanical stability.

[0077] In some embodiments, the electrode assembly 10 is in a jelly-roll structure. By way of example, the positive electrode sheet and the negative electrode sheet are both in a strip structure, and the positive electrode sheet, the separator, and the negative electrode sheet are wound into the jelly-roll structure.

[0078] In some embodiments, the electrode assembly 10 is in a stack structure.

[0079] By way of example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be alternately stacked.

[0080] By way of example, a plurality of positive electrode sheets can be provided, and the negative electrode sheet is folded to form a plurality of stacked folding sections, and one positive electrode sheet is clamped between adjacent folding sections.

[0081] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded segments that are stacked.

[0082] In some embodiments, the electrode assembly 10 can have a cylindrical shape, a flat shape, a polygonal shape, or the like.

[0083] In some embodiments, the housing 20 includes a casing 21 having an opening and an end cap 22 for covering the opening.

[0084] The casing 21 is a component for cooperating with the end cap 22 to form an internal cavity of the battery cell 6, which can be used to accommodate the electrode assembly 10, the electrolyte, and other components.

[0085] The casing 21 and the end cap 22 can be separate components. As an example, the casing 21 can be provided with an opening, and the end cap 22 can be used to cover the opening to form the internal cavity of the battery cell 6.

[0086] The casing 21 can have various shapes and sizes, such as a cuboid shape, a cylindrical shape, a hexagonal prism shape, or the like. In particular, the shape of the casing 21 can be determined according to the specific shape and size of the electrode assembly 10. The casing 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, aluminum plastic film, steel plastic film, or the like.

[0087] The end cap 22 can have a shape that is adapted to the shape of the casing 21 to cooperate with the casing 21. The material of the end cap 22 can be the same as or different from that of the casing 21. Optionally, the end cap 22 can be made of a material having a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, or the like), so that the end cap 22 is less likely to deform when subjected to extrusion or impact, and the battery cell 6 can have higher structural strength and improved reliability.

[0088] The end cap 22 can be connected to the casing 21 by welding, bonding, clamping, or other means.

[0089] The casing 21 can be open at one end or both ends. In some examples, the casing 21 can have a structure that is open at one side, and the end cap 22 is provided as one end cap to cover the casing 21. In other examples, the casing 21 can have a structure that is open at both ends, and the end cap 22 is provided as two end caps to cover the two openings of the casing 21.

[0090] In some embodiments, the battery cell 6 includes electrode terminals 30 disposed on the outer shell 20, the electrode terminals 30 being electrically connected to the tab 12 of the electrode assembly 10. The electrode terminals 30 can be used to electrically connect the electrode assembly 10 with an external circuit of the battery cell 6 to enable charging and discharging of the electrode assembly 10. Exemplarily, at least a portion of the electrode terminals 30 is exposed to the outside of the battery cell 6 to facilitate connection with other components (e.g. busbar components) to thereby lead out the electrical energy generated by the electrode assembly 10.

[0091] Exemplarily, the electrode terminals 30 can be disposed on the end cap 22 or on the housing 21.

[0092] In some embodiments, the electrode assembly 10 includes a main body portion 11 and a tab 12. Exemplarily, the main body portion 11 can include a portion of a positive electrode sheet coated with an active material layer, a portion of a negative electrode sheet coated with an active material layer, and a separator. The active material in the active material layer is used to undergo an electrochemical reaction with an electrolyte or the like to generate a charging and discharging process.

[0093] In some embodiments, the tab 12 can be provided in a plurality. The plurality of tabs 12 includes a positive tab and a negative tab, which can be led out from the same end of the main body portion 11 or from opposite ends of the main body portion 11, respectively. Exemplarily, the electrode terminals 30 can be two, the two electrode terminals 30 being electrically connected to the positive tab and the negative tab, respectively.

[0094] In some embodiments, the tab 12 extends from an end of the main body portion 11 facing the electrode terminal 30.

[0095] In some examples, the two electrode terminals 30 are located on the same side of the main body portion 11, and the positive tab and the negative tab extend from the same end of the main body portion 11. In other examples, the two electrode terminals 30 are located on the two sides of the main body portion 11, respectively, and the positive tab extends from an end of the main body portion 11 facing one of the electrode terminals 30, and the negative tab extends from an end of the main body portion 11 facing the other of the electrode terminals 30.

[0096] In some embodiments, the tab 12 includes a plurality of tab layers stacked together. By providing a plurality of tab layers, the overcurrent capacity of the tab 12 can be increased, the heat generation of the tab 12 can be reduced, and the risk of the tab 12 being blown out can be reduced.

[0097] Exemplarily, the tab layers are metal foils, the surfaces of which are not coated with an active material layer.

[0098] Exemplarily, the tab layers of the positive tab are aluminum foils, and the tab layers of the negative tab are copper foils.

[0099] In some embodiments, the end cover 22 is provided with an electrode lead-out hole that penetrates the end cover 22 in the thickness direction of the end cover 22. The electrode terminal 30 penetrates the electrode lead-out hole. Illustratively, the battery cell 6 further includes a terminal plate 50 that is located outside the end cover 22, and the portion of the electrode terminal 30 that extends outside the end cover 22 is riveted to the terminal plate 50. Illustratively, the terminal plate 50 is used to connect to an external bus bar.

[0100] In some embodiments, the battery cell 6 includes a housing 20, an electrode terminal 30, an electrode assembly 10, and a connecting tab 40. The electrode terminal 30 is disposed in the housing 20. The electrode assembly 10 is accommodated in the housing 20, and includes a main body 11 and a tab 12 that extends from one end of the main body 11 that faces the electrode terminal 30. The connecting tab 40 is welded to the tab 12 and forms a first weld W1, and the connecting tab 40, the tab 12, and the electrode terminal 30 are welded and form a second weld W2.

[0101] In some examples, the first weld W1 and the second weld W2 can be directly connected. Illustratively, during operation of the battery cell 6, the current on the tab 12 can be conducted to the electrode terminal 30 through the first weld W1 and the second weld W2.

[0102] In other examples, the first weld W1 and the second weld W2 are spaced apart by a distance and are connected by a portion of the connecting tab 40. Illustratively, during operation of the battery cell 6, a portion of the current on the tab 12 is conducted to the electrode terminal 30 through the second weld W2, and another portion of the current on the tab 12 can be conducted to the electrode terminal 30 via the first weld W1, the connecting tab 40, and the second weld W2.

[0103] The first weld W1 can be one or multiple. The second weld W2 can be one or multiple.

[0104] The first weld W1 and the second weld W2 can be formed by the same welding process or by different welding processes.

[0105] In some examples, at least a portion of the connecting tab 40 is disposed between the tab 12 and the electrode terminal 30 and is welded to the tab 12 and the electrode terminal 30; in other examples, at least a portion of the tab 12 is disposed between the connecting tab 40 and the electrode terminal 30 and is welded to the connecting tab 40 and the electrode terminal 30.

[0106] The area of the first weld W1 can be greater than, equal to, or less than the area of the second weld W2.

[0107] By the first welding portion W1 and the second welding portion W2, a plurality of conductive paths can be formed between the tab 12 and the electrode terminal 30, so as to improve the overcurrent capacity between the tab 12 and the electrode terminal 30 and reduce heat generation. Compared with the second welding portion W2, the first welding portion W1 is formed independently of the electrode terminal 30, has less influence on the tab 12 (for example, the tab 12 is less subjected to thermal stress), and the portion of the tab 12 close to the first welding portion W1 is less likely to be torn; when the battery cell 6 is subjected to external impact, even if the portion of the tab 12 close to the second welding portion W2 is torn, the current can be conducted to the electrode terminal 30 via the first welding portion W1, the connecting piece 40 and the second welding portion W2, so as to reduce the risk of connection failure of the tab 12 and the electrode terminal 30 and improve the reliability of the battery cell 6.

[0108] In some embodiments, the portion of the tab 12 not welded with other components is directly connected to the first welding portion W1. For example, a plurality of tab layers of the tab 12 are directly connected to the first welding portion W1. For example, the thickness of the tab layer is 2-30 μm. Optionally, the thickness of the tab layer is 5-15 μm.

[0109] In some embodiments, the first welding portion W1 is directly connected to the second welding portion W2.

[0110] For example, the first welding portion W1 is arranged along the outer periphery of the second welding portion W2. For example, the first welding portion W1 can extend along the outer periphery of the second welding portion W2 for 0.25 turns, 0.5 turns, 0.75 turns or 1 turn.

[0111] During the operation of the battery cell 6, the current can be directly transmitted between the first welding portion W1 and the second welding portion W2, so as to shorten the conductive path, reduce the resistance, improve the overcurrent capacity and reduce heat generation.

[0112] In some embodiments, in the extension direction of the tab 12, at least part of the first welding portion W1 is located between the root 123 of the tab 12 and the second welding portion W2.

[0113] For example, the tab 12 extends outwardly from the end face of the main body portion 11, and the portion of the tab 12 close to the end face of the main body portion 11 can be the root 123 of the tab 12.

[0114] The current generated by the body portion 11 flows to the first welding portion W1 and the second welding portion W2 through the root portion 123 of the tab 12; when the battery cell 6 is subjected to external impact, even if the portion of the tab 12 close to the second welding portion W2 is torn, the current can be conducted to the electrode terminal 30 via the root portion 123, the first welding portion W1 and the second welding portion W2; at least part of the first welding portion W1 is located between the root portion 123 of the tab 12 and the second welding portion W2, which can reduce the current flowing to the tab 12 on the side away from the root portion 123 of the second welding portion W2, thereby shortening the conduction path, reducing heat generation and improving the overcurrent capacity.

[0115] In some embodiments, at least part of the first welding portion W1 is arranged around the second welding portion W2, which can reduce the difference in distance between different parts of the first welding portion W1 and the second welding portion W2, improve the uniformity of overcurrent, and reduce heat generation.

[0116] In some embodiments, the outer periphery of the second welding portion W2 is directly connected with the first welding portion W1, so as to increase the overcurrent area between the first welding portion W1 and the second welding portion W2, reduce the resistance, shorten the conduction path, improve the overcurrent capacity and reduce heat generation.

[0117] Exemplarily, the first welding portion W1 separates the second welding portion W2 from the tab layer, so as to reduce the risk of tearing of the tab layer.

[0118] In other embodiments, the first welding portion W1 is arranged around and spaced apart from the second welding portion W2. When the body portion 11 vibrates and pulls the tab 12, the first welding portion W1 can block the pulling force and reduce the stress at the connection between the tab 12 and the second welding portion W2.

[0119] In some embodiments, in the thickness direction Z of the connecting piece 40, the projection area of the first welding portion W1 is greater than or equal to 0.2 times the projection area of the second welding portion W2, so as to improve the overcurrent capacity between the tab 12 and the electrode terminal 30, reduce the risk of connection failure between the tab 12 and the electrode terminal 30, and improve the reliability of the battery cell 6.

[0120] Exemplarily, the area of the second welding portion W2 can be set according to the overcurrent area requirement of the battery cell 6, in other words, even without the first welding portion W1, the area of the second welding portion W2 can meet the overcurrent requirement under normal circumstances. The first welding portion W1 is arranged, and the projection area of the first welding portion W1 is greater than or equal to 0.2 times the projection area of the second welding portion W2, so as to meet the overcurrent requirement when the tab 12 is torn or other accidents occur.

[0121] In some embodiments, the thickness of the connecting tab 40 is 0.1mm-1.5mm. For example, the thickness of the connecting tab 40 can be 0.1mm, 0.2mm, 0.4mm, 0.5mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.4mm or 1.5mm.

[0122] Limiting the thickness of the connecting tab 40 to be greater than or equal to 0.1mm can improve the strength of the connecting tab 40 and reduce the risk of tearing of the connecting tab 40. Limiting the thickness of the connecting tab 40 to be less than or equal to 1.5mm can reduce the difficulty of welding, reduce the heat generated by welding, reduce the thermal stress on the tab 12, and reduce the risk of tearing of the tab 12.

[0123] In some embodiments, the thickness of the connecting tab 40 is 0.2mm-0.8mm.

[0124] In some embodiments, the electrode terminal 30 is an integrally formed structure. A portion of the electrode terminal 30 is located on the inner side of the end cover 22 and is welded to the connecting tab 40 and the tab 12. Another portion of the electrode terminal 30 is located on the outer side of the end cover 22 and is riveted to the terminal plate 50.

[0125] In some embodiments, the connecting tab 40 and the tab 12 are connected by ultrasonic welding and form a first welding portion W1. During ultrasonic welding, the tab 12 is less affected by heat. After welding is completed, the portion of the tab 12 near the first welding portion W1 is less likely to tear.

[0126] In some embodiments, the connecting tab 40, the tab 12 and the electrode terminal 30 are connected by laser welding and form a second welding portion W2. Using laser welding can reduce the difficulty of welding and improve the strength of the second welding portion W2 formed by welding.

[0127] In some embodiments, at least a portion of the connecting tab 40 is located between the electrode terminal 30 and the tab 12 in the thickness direction Z of the connecting tab 40 and is welded to the tab 12 and the electrode terminal 30, respectively. Specifically, the portion of the connecting tab 40 located between the electrode terminal 30 and the tab 12 is welded to the tab 12 and forms a first welding portion W1, and the portion of the connecting tab 40 located between the electrode terminal 30 and the tab 12 is welded to the tab 12 and the electrode terminal 30 and forms a second welding portion W2.

[0128] By arranging the connecting tab 40 between the tab 12 and the electrode terminal 30, the risk of interference between the connecting tab 40 and the tab 12 during bending of the tab 12 can be reduced.

[0129] In some embodiments, the tab 12 includes a laminated section 121 and a bent section 122. The laminated section 121 is attached to the connecting piece 40 in the thickness direction Z, and the bent section 122 is bent from one end of the laminated section 121 and connected to the main body 11. The laminated section 121 is welded to the connecting piece 40 and forms a first welding portion W1, and the connecting piece 40, the laminated section 121, and the electrode terminal 30 are welded and form a second welding portion W2.

[0130] By bending the tab 12, the space occupied by the tab 12 in the thickness direction Z can be reduced, and the space utilization can be improved.

[0131] In some embodiments, the bent section 122 is bent from one end of the laminated section 121 in a first direction Y. Illustratively, the first direction Y is perpendicular to the thickness direction Z. Illustratively, the first direction Y can be parallel to the width direction of the end cover.

[0132] In some embodiments, a portion of the connecting piece 40 does not overlap the laminated section 121 in the thickness direction Z. The connecting piece 40 has a larger size, which can reduce the risk of false welding when welding the connecting piece 40 and the laminated section 121, and improve the connection strength. In addition, when welding the laminated section 121, the connecting piece 40 and the electrode terminal 30, a portion of the connecting piece 40 can not be blocked by the laminated section 121, thereby facilitating positioning of the connecting piece 40, improving welding accuracy, and reducing the risk of false welding.

[0133] In some embodiments, in the first direction Y, the size of the connecting piece 40 is greater than the size of the laminated section 121.

[0134] In the first direction Y, the connecting piece 40 has a larger size, which can reduce the risk of false welding when welding the connecting piece 40 and the laminated section 121, and improve the connection strength.

[0135] In some embodiments, the laminated section 121 includes a first edge 121a located at one end of the laminated section 121 away from the bent section 122. A portion of the connecting piece 40 extends beyond the first edge 121a.

[0136] The portion of the connecting piece 40 extending beyond the first edge 121a is exposed, and when welding the tab 12, the connecting piece 40 and the electrode terminal 30, the portion of the connecting piece 40 extending beyond the first edge 121a can be used for positioning, thereby improving welding accuracy and reducing the risk of false welding.

[0137] In some embodiments, the laminated section 121 includes two second edges 121b oppositely arranged and connected to the first edge 121a. In the arrangement direction of the two second edges 121b, the two second edges 121b both extend beyond the connecting tab 40. In the arrangement direction of the two second edges 121b, the connecting tab 40 can have a size smaller than that of the laminated section 121, thereby saving space and improving energy density.

[0138] In some embodiments, the two second edges 121b are oppositely arranged along a second direction X. Exemplarily, the first direction Y, the second direction X, and the thickness direction Z are perpendicular to each other. Alternatively, the second direction X is parallel to the length direction of the end cap.

[0139] In some embodiments, the electrode terminal 30 has an inner surface 31 facing the connecting tab 40, and the inner surface 31 is in contact with the connecting tab 40 in the thickness direction Z. The laminated section 121 includes two oppositely arranged second edges 121b; in the arrangement direction of the two second edges 121b, both ends of the connecting tab 40 extend beyond the inner surface 31, and both of the two second edges 121b extend beyond the connecting tab 40. The connecting tab 40 can cover the electrode terminal 30 as much as possible, thereby reducing the risk of false welding and improving the contact area and connection strength between the connecting tab 40 and the electrode terminal 30. In the arrangement direction of the two second edges 121b, the part of the connecting tab 40 extending beyond the electrode terminal 30 is not connected to the electrode terminal 30, and therefore, the connecting tab 40 can have a size smaller than that of the laminated section 121, thereby saving space and improving energy density.

[0140] In some embodiments, in the second direction X, the size of the connecting tab 40 is smaller than that of the laminated section 121 and larger than that of the electrode terminal 30. In the second direction X, the size of the connecting tab 40 is larger than that of the electrode terminal 30, so that the connecting tab 40 can cover the electrode terminal 30 as much as possible, thereby reducing the risk of false welding. In the second direction X, the part of the connecting tab 40 extending beyond the electrode terminal 30 is not connected to the electrode terminal 30, and therefore, the connecting tab 40 can have a size smaller than that of the laminated section 121, thereby saving space and improving energy density.

[0141] In some embodiments, the root 123 connects the bent section 122 and the main body 11.

[0142] In some embodiments, the positive and negative tabs extend from the two ends of the main body 11, respectively.

[0143] In some embodiments, the second welding portion W2 is in a strip shape, and the second welding portion W2 extends along the second direction X.

[0144] Optionally, the second weld W2 is a plurality of second welds W2, and the plurality of second welds W2 are arranged at intervals along the first direction Y. The outer periphery of each second weld W2 is directly connected to the first weld W1.

[0145] In some embodiments, the first weld W1 and the second weld W2 constitute a weld. The dimension of the second weld W2 along the second direction X is L1, the dimension of the weld along the second direction X is L2, and the dimension of the connecting tab 40 along the second direction X is L3, L3≥L2≥L1.

[0146] The dimension of the second weld W2 along the first direction Y is W1, the dimension of the weld along the first direction Y is W2, and W2≥W1. The dimension of the connecting tab 40 along the first direction Y is greater than W2.

[0147] In some embodiments, the connecting tab 40 is rectangular.

[0148] In some embodiments, the battery cell 6 can be assembled according to the following steps: first, the tab 12 and the connecting tab 40 are ultrasonically welded and form an ultrasonic weld (i.e., the first weld W1); then, the connecting tab 40 is attached to the electrode terminal 30; then, laser is irradiated from the tab 12 side, the laser melts a portion of the ultrasonic weld and a portion of the electrode terminal 30 and forms a molten pool, and the molten pool solidifies to form the second weld W2 (i.e., the laser weld).

[0149] When the laser is irradiated, the laser acts on the ultrasonic weld, so that the non-welded portion of the tab 12 is less affected by heat.

[0150] Exemplarily, the dimension of the ultrasonic weld along the first direction Y is W2, and the dimension of the ultrasonic weld along the second direction X is L2.

[0151] In some embodiments, in the thickness direction Z of the connecting tab 40, the projected area of the ultrasonic weld is greater than or equal to 1.2 times the projected area of the second weld W2.

[0152] In other embodiments, the battery cell 6 can be assembled according to the following steps: first, the tab 12 and the connecting tab 40 are ultrasonically welded and form an ultrasonic weld (i.e., the first weld W1); then, the connecting tab 40 is attached to the electrode terminal 30; then, laser is irradiated from the tab 12 side, the laser melts a portion of the ultrasonic weld and a portion of the electrode terminal 30 and forms a molten pool, and the molten pool solidifies to form the second weld W2 (i.e., the laser weld).

[0153] In yet some embodiments, the battery cell 6 can be assembled in the following steps: first, the tab 12 and the connecting tab 40 are ultrasonically welded and form an ultrasonic weld bead; then, the connecting tab 40 is attached to the electrode terminal 30; laser is irradiated on the ultrasonic weld bead and the part of the tab 12 which is not ultrasonically welded, the laser melts part of the ultrasonic weld bead, part of the tab 12, part of the connecting tab 40 and part of the electrode terminal 30 and forms a molten pool, the molten pool solidifies to form a second weld W2 (i.e. laser weld bead). The remaining part of the ultrasonic weld bead (i.e. the part which is not melted by the laser irradiation) forms a first weld W1.

[0154] In some embodiments, the material of the tab 12, the material of the connecting tab 40 and the material of the electrode terminal 30 are the same.

[0155] According to some embodiments of the present application, the present application further provides a battery comprising a plurality of the battery cell 6 of any of the above embodiments.

[0156] According to some embodiments of the present application, the present application further provides an electric device comprising the battery cell 6 of any of the above embodiments, the battery cell 6 is configured to provide electric energy for the electric device. The electric device can be any of the devices or systems mentioned above which use the battery cell 6.

[0157] Referring to FIGS. 3-8, the present application provides a battery cell 6 comprising a housing 20, an electrode terminal 30, an electrode assembly 10 and a connecting tab 40. The electrode terminal 30 is disposed on the housing 20. The electrode assembly 10 is accommodated in the housing 20, the electrode assembly 10 comprises a main body 11 and a tab 12, the tab 12 extends from one end of the main body 11 which faces the electrode terminal 30. At least part of the connecting tab 40 is located between the tab 12 and the electrode terminal 30.

[0158] The connecting tab 40 and the tab 12 are connected by ultrasonic welding and form a first weld W1. The connecting tab 40, the tab 12 and the electrode terminal 30 are connected by laser welding and form a second weld W2. The second weld W2 is surrounded by the first weld W1, and the outer periphery of the second weld W2 is directly connected to the first weld W1.

[0159] Although the present application has been described with reference to the preferred embodiments, various modifications can be made to the present application without departing from the scope of the present application, and equivalent substitutions can be made to the components thereof, especially, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, comprising: shell; an electrode terminal, disposed on the housing; an electrode assembly housed in the housing, the electrode assembly comprising a main body and a tab, the tab extending from one end of the main body facing the electrode terminal; A connecting piece is welded to the electrode tab to form a first welding portion, and the connecting piece, the electrode tab, and the electrode terminal are welded to form a second welding portion.

2. The battery cell according to claim 1, wherein: The first welding portion is directly connected to the second welding portion.

3. The battery cell according to claim 1 or 2, wherein: At least a portion of the first welding portion is disposed around the second welding portion.

4. The battery cell according to claim 3, wherein: The outer periphery of the second welding portion is directly connected to the first welding portion.

5. The battery cell according to any one of claims 1 to 4, wherein: In the thickness direction of the connecting piece, at least a portion of the connecting piece is located between the electrode terminal and the electrode tab, and is welded to the electrode tab and the electrode terminal, respectively. The battery cell according to claim 5 , wherein: The tab includes a stacking section and a bending section, wherein the stacking section is attached to the connecting piece in the thickness direction, and the bending section is bent from one end of the stacking section and connected to the main body; The stacked sections are welded to the connection sheet to form a first weld portion, and the connection sheet, the stacked sections, and the electrode terminal are welded to form a second weld portion.

7. The battery cell according to claim 6, wherein: A portion of the connecting sheet does not overlap with the laminated section in the thickness direction.

8. The battery cell according to claim 6 or 7, wherein: The stacked section includes a first edge and two second edges, wherein the first edge is located at an end of the stacked section away from the bending section, and the two second edges are oppositely arranged and connected to the first edge; A portion of the connecting piece extends beyond the first edge; and in the arrangement direction of the two second edges, both of the two second edges extend beyond the connecting piece.

9. The battery cell according to claim 6 or 7, wherein: The electrode terminal has an inner surface facing the connecting piece, and the inner surface is in contact with the connecting piece in the thickness direction; The stacking section includes two second edges arranged opposite to each other; in the arrangement direction of the two second edges, both ends of the connecting piece extend beyond the inner surface, and both second edges extend beyond the connecting piece.

10. The battery cell according to any one of claims 1 to 9, wherein: In the extending direction of the electrode tab, at least a portion of the first welding portion is located between the root portion of the electrode tab and the second welding portion.

11. The battery cell according to any one of claims 1 to 10, wherein: In a thickness direction of the connecting sheet, a projected area of ​​the first welding portion is greater than or equal to 0.2 times a projected area of ​​the second welding portion.

12. The battery cell according to any one of claims 1 to 11, wherein: The connecting piece and the tab are connected by ultrasonic welding to form the first welding portion, and the connecting piece, the tab and the electrode terminal are connected by laser welding to form the second welding portion.

13. The battery cell according to any one of claims 1 to 12, wherein: The thickness of the connecting piece is 0.1 mm to 1.5 mm.

14. A battery comprising a plurality of battery cells according to any one of claims 1 to 13.

15. An electrical device comprising the battery according to claim 14, wherein the battery is used to provide electrical energy.

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