Battery cell, battery and electric device

Abstract

The utility model discloses a battery monomer, a battery and a power utilization device. The battery monomer comprises a shell, an electrode terminal, an electrode assembly and a connecting piece. The electrode terminal is arranged on the shell. The electrode assembly is housed within the housing. The electrode assembly comprises a main body part and a tab, and the tab extends out from one end, facing the electrode terminal, of the main body part. The connecting sheet and the tab are welded to form a first welding part, and the connecting sheet, the tab and the electrode terminal are welded to form a second welding part. 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, so that the overcurrent capacity between the tab and the electrode terminal is improved, and heat production is reduced.

Description

Technical Field

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

[0002] Battery monomers are widely used in electronic devices, such as mobile phones, laptop computers, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc.

[0003] How to improve the reliability of battery cells is a research direction in battery technology. Utility Model Content

[0004] The present application provides a battery cell, a battery, and an electrical device, which can improve the reliability of the battery cell.

[0005] In a first aspect, the present application provides a battery cell, which includes a housing, an electrode terminal, an electrode assembly and a connecting piece. The electrode terminal is disposed in the housing. The electrode assembly is accommodated in the housing. The electrode assembly includes a main body and a tab, and the tab extends from one end of the main body facing the electrode terminal. The connecting piece is welded to the tab to form a first welding portion, and the connecting piece, the tab and the electrode terminal are welded to form a second welding portion.

[0006] Through the first welding part and the second welding part, multiple conductive paths can be formed between the pole tab and the electrode terminal, thereby improving the current capacity between the pole 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 pole tab, and the part of the pole tab close to the first welding part is not easy to tear; when the battery cell is subjected to external impact, even if the part of the pole tab close to the second welding part is torn, 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 failure of the connection between the pole tab and the electrode terminal and improving the reliability of the battery cell.

[0007] In some embodiments, the first welding portion is directly connected to the second welding portion. During the operation of the battery cell, current can be directly transmitted between the first welding portion and the second welding portion, thereby shortening the conductive path, reducing resistance, improving current flow capacity, and reducing heat generation.

[0008] In some embodiments, at least a portion of the first welding portion is disposed around the second welding portion, which can reduce the distance difference between different portions of the first welding portion and the second welding portion, improve the uniformity of the flow, and reduce heat generation.

[0009] In some embodiments, the outer periphery of the second welding portion is directly connected to the first welding portion to increase the flow area between the first welding portion and the second welding portion, reduce resistance, shorten the conductive path, improve the flow capacity, and reduce heat generation.

[0010] In some embodiments, in the thickness direction of the connecting sheet, at least a portion of the connecting sheet is located between the electrode terminal and the tab, and is welded to the tab and the electrode terminal, respectively. Providing the connecting sheet between the tab and the electrode terminal can reduce the risk of interference between the connecting sheet and the tab during bending of the tab.

[0011] In some embodiments, the tab includes a stacking section and a bending section, the stacking section is bonded to the connecting sheet in the thickness direction, and the bending section is bent from one end of the stacking section and connected to the main body. The stacking section is welded to the connecting sheet to form a first welding portion, and the connecting sheet, the stacking section and the electrode terminal are welded to form a second welding portion. By bending the tab, the space occupied by the tab in the thickness direction can be reduced, thereby improving space utilization.

[0012] In some embodiments, a portion of the connecting piece does not overlap with the stacking section in the thickness direction. The connecting piece has a larger size, which can reduce the risk of cold welding and improve the connection strength when welding the connecting piece and the stacking section; in addition, when welding the stacking section, the connecting piece and the electrode terminal, a portion of the connecting piece may not be blocked by the stacking section, thereby facilitating the positioning of the connecting piece, improving the welding accuracy and reducing the risk of cold welding.

[0013] In some embodiments, the stacking section includes a first edge and two second edges, the first edge is located at one end of the stacking section away from the bending section, and the two second edges are arranged opposite to and connected to the first edge. A portion of the connecting piece exceeds the first edge; in the arrangement direction of the two second edges, the two second edges both exceed the connecting piece.

[0014] When welding the tab, the connecting piece and the electrode terminal, the portion of the connecting piece that exceeds the first edge can be used for positioning, thereby improving welding accuracy and reducing the risk of cold welding. In the arrangement direction of the two second edges, the connecting piece can have a size smaller than the stacking section, thereby saving space and improving energy density.

[0015] 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 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. The connecting piece can cover the electrode terminal as much as possible, thereby reducing the risk of cold welding and improving 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, so the connecting piece can have a size smaller than the stacking section, thereby saving space and improving energy density.

[0016] 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.

[0017] 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 carrying 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.

[0018] In some embodiments, the connecting piece and the pole ear are connected by ultrasonic welding to form a first welding portion, and the connecting piece, the pole ear and the electrode terminal are connected by laser welding to form a second welding portion. During ultrasonic welding, the pole ear is less affected by heat; after welding, the portion of the pole ear close to the first welding portion is not easy to tear. Using laser welding can reduce the difficulty of welding and improve the strength of the second welding portion formed by welding.

[0019] In some embodiments, the thickness of the connecting sheet is 0.1 mm-1.5 mm. Limiting the thickness of the connecting sheet to be greater than or equal to 0.1 mm can improve the strength of the connecting sheet and reduce the risk of tearing the connecting sheet; limiting the thickness of the connecting sheet to be 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.

[0020] 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.

[0021] In a third aspect, the present application provides an electrical device, comprising a battery provided according to any embodiment of the second aspect, and the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0023] Figure 1A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0024] Figure 2 An exploded schematic diagram of a battery provided in some embodiments of the present application;

[0025] Figure 3 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0026] Figure 4 A schematic cross-sectional view of a battery cell provided in some embodiments of the present application;

[0027] Figure 5 Another cross-sectional schematic diagram of a battery cell provided in some embodiments of the present application;

[0028] Figure 6 for Figure 4 An enlarged schematic diagram at the circle frame;

[0029] Figure 7 for Figure 5 Enlarged schematic diagram at the box;

[0030] Figure 8 Another schematic cross-sectional view of a battery cell provided in some embodiments of the present application.

[0031] The following are the descriptions of the reference numerals:

[0032] 1. Vehicle; 2. Battery; 3. Controller; 4. Motor; 5. Box; 5a. First box part; 5b. Second box part; 5c. Accommodation space; 6. Battery cell;

[0033] 10. electrode assembly; 11. main body; 12. pole ear; 121. stacking section; 121a. first edge; 121b. second edge; 122. bending section; 123. root;

[0034] 20. housing; 21. shell; 22. end cover;

[0035] 30. electrode terminal; 31. inner surface; 40. connecting piece; 50. terminal board;

[0036] W1, first welding part; W2, second welding part; X, second direction; Y, first direction; Z, thickness direction. DETAILED DESCRIPTION

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] 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.

[0042] 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 various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0043] The term "plurality" used in the present application refers to two or more (including two).

[0044] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0045] Battery cells may include but are not limited to lithium ion battery cells, sodium ion battery cells, sodium lithium ion battery cells, lithium metal battery cells, sodium metal battery cells, lithium sulfur battery cells, magnesium ion battery cells, nickel metal hydride battery cells, nickel cadmium battery cells, lead storage battery cells, etc.

[0046] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery, etc. There is no particular limitation in the present application.

[0047] 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.

[0048] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0049] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are accommodated in the case.

[0050] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0051] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0052] Generally, it includes an electrode assembly, a shell and an electrode terminal. The electrode assembly is contained in the shell, and the electrode terminal is provided with a shell. The electrode assembly includes a tab, which is electrically connected to the electrode terminal; the electrode terminal can be used to electrically connect the electrode assembly to the circuit outside the battery cell to realize the charging or discharging of the battery cell.

[0053] In the related art, the tabs can be directly connected to the electrode terminals by welding, and the welding point between the tabs and the electrode terminals can transmit current. However, the tabs are thin, and when the battery cell is subjected to external impact, the part of the tab near the welding point is easy to tear, thereby reducing the current flow capacity between the tabs and the electrode terminals, increasing heat generation, and even causing the connection between the tabs and the electrode terminals to fail, affecting the reliability of the battery cell.

[0054] In view of this, an embodiment of the present application provides a technical solution, which connects the pole lug and the electrode terminal by setting a connecting piece, and forms multiple conductive paths between the pole lug and the electrode terminal, thereby improving the current flow capacity between the pole lug and the electrode terminal, reducing heat generation, reducing the risk of failure of the connection between the pole lug and the electrode terminal, and improving the reliability of the battery cell.

[0055] The technical solution described in the embodiments of the present application is applicable to electrical devices using batteries.

[0056] The electrical device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle may be a fuel vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, and the like; the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, and the like; 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, and the like; the electric tool may include a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and an electric tool for railways, 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, and the like. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0057] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0058] Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application.

[0059] like Figure 1 As shown, a battery 2 is disposed inside the vehicle 1, and the battery 2 may be disposed at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1, for example, the battery 2 may be used as an operating power source for the vehicle 1.

[0060] The vehicle 1 may further include a controller 3 and a motor 4 , wherein the controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of starting, navigating, and driving the vehicle 1 .

[0061] In some embodiments of the present application, the battery 2 can not only serve as an operating power source for the vehicle 1, but also serve as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0062] Figure 2 An exploded schematic diagram of a battery provided for some embodiments of the present application.

[0063] like Figure 2 As shown, the battery 2 includes a box body 5 and a battery cell 6 , and the battery cell 6 is accommodated in the box body 5 .

[0064] 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 portion 5a and a second box portion 5b, the first box portion 5a and the second box portion 5b cover each other, and the first box portion 5a and the second box portion 5b jointly define a storage space 5c for accommodating the battery cell 6. The second box portion 5b can be a hollow structure with one end open, the first box portion 5a is a plate-like structure, and the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c; the first box portion 5a and the second box portion 5b can also be hollow structures with one side open, and the open side of the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c. Of course, the first box portion 5a and the second box portion 5b can be of various shapes, such as a cylinder, a cuboid, etc.

[0065] In order to improve the sealing performance after the first box body part 5a and the second box body part 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body part 5a and the second box body part 5b.

[0066] Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box.

[0067] In the battery 2, there can be one or more battery cells 6. If there are more than one battery cell 6, the battery cells 6 can be connected in series, in parallel or in mixed connection. Mixed connection means that the battery cells 6 are both connected in series and in parallel. The battery cells 6 can be directly connected in series, in parallel or in mixed connection, and then the whole formed by the battery cells 6 can be accommodated in the box 5; of course, the battery cells 6 can also be connected in series, in parallel or in mixed connection to form a battery module, and then the battery modules can be connected in series, in parallel or in mixed connection to form a whole, and then accommodated in the box 5.

[0068] Figure 3 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application; Figure 4 A schematic cross-sectional view of a battery cell provided in some embodiments of the present application; Figure 5 Another cross-sectional schematic diagram of a battery cell provided in some embodiments of the present application; Figure 6 for Figure 4 An enlarged schematic diagram at the circle frame;

[0069] Figure 7 for Figure 5 Enlarged schematic diagram at the box; Figure 8 Another schematic cross-sectional view of a battery cell provided in some embodiments of the present application.

[0070] Reference Figures 3 to 8 An embodiment of the present application provides a battery cell 6 , which includes a housing 20 and an electrode assembly 10 , wherein the electrode assembly 10 is accommodated in the housing 20 .

[0071] The electrode assembly 10 includes a positive electrode and a negative electrode. During the charge and discharge process of the battery cell 6, active ions (such as lithium ions) are inserted and removed back and forth between the positive electrode and the negative electrode. Optionally, the electrode assembly 10 also includes a separator disposed between the positive electrode and the negative electrode, which can reduce the risk of short circuit between the positive and negative electrodes while allowing active ions to pass through.

[0072] The housing 20 is used to encapsulate the electrode assembly 10 and the electrolyte and other components. The housing 20 can be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing) or an aluminum-plastic film.

[0073] In some embodiments, the positive electrode includes a positive electrode sheet. The positive electrode sheet may 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.

[0074] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two facing surfaces of the positive electrode current collector.

[0075] In some embodiments, the negative electrode includes a negative electrode sheet. The negative electrode sheet may 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.

[0076] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0077] In some embodiments, the electrode assembly 10 further includes a separator, which is used to separate the positive electrode sheet from the negative electrode sheet. The separator can reduce the risk of short circuit between the positive and negative electrodes, while allowing active ions to pass through.

[0078] In some embodiments, the isolation element includes an isolation membrane. The isolation membrane of the present application can be any known porous structure isolation membrane with good chemical stability and mechanical stability.

[0079] In some embodiments, the electrode assembly 10 is a wound structure. Exemplarily, both the positive electrode sheet and the negative electrode sheet are strip-shaped structures, and the positive electrode sheet, the separator, and the negative electrode sheet are wound into a wound structure.

[0080] In some embodiments, the electrode assembly 10 is a laminate structure.

[0081] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets may be alternately stacked.

[0082] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0083] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded sections that are stacked.

[0084] In some embodiments, the shape of the electrode assembly 10 can be cylindrical, flat, or polygonal.

[0085] In some embodiments, the housing 20 includes a shell 21 and an end cover 22 , the shell 21 has an opening, and the end cover 22 is used to cover the opening.

[0086] The housing 21 is a component used to cooperate with the end cover 22 to form an internal cavity of the battery cell 6. The formed internal cavity can be used to accommodate the electrode assembly 10, electrolyte and other components.

[0087] The housing 21 and the end cap 22 may be independent components. For example, an opening may be provided on the housing 21, and the end cap 22 may cover the opening to form an internal cavity of the battery cell 6.

[0088] The shell 21 can be in various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism shape, etc. Specifically, the shape of the shell 21 can be determined according to the specific shape and size of the electrode assembly 10. The shell 21 can be made of various materials, for example, the material of the shell 21 includes but is not limited to copper, iron, aluminum, stainless steel, aluminum alloy, aluminum-plastic film, steel-plastic film, etc.

[0089] The shape of the end cap 22 can be adapted to the shape of the shell 21 to match the shell 21. The material of the end cap 22 can be the same as or different from the material of the shell 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easily deformed when squeezed and collided, so that the battery cell 6 can have a higher structural strength and the reliability performance can also be improved.

[0090] The end cover 22 is connected to the housing 21 by welding, bonding, clamping or other methods.

[0091] The housing 21 may be open at one end or at both ends. In some examples, the housing 21 may be a structure with an opening at one end, and an end cap 22 is provided and covers the housing 21. In other examples, the housing 21 may be a structure with openings at both ends, and two end caps 22 are provided, and the two end caps 22 cover the two openings of the housing 21 respectively.

[0092] In some embodiments, the battery cell 6 includes an electrode terminal 30 disposed on the housing 20, and the electrode terminal 30 is electrically connected to the tab 12 of the electrode assembly 10. The electrode terminal 30 can be used to electrically connect the electrode assembly 10 to the circuit outside the battery cell 6 to realize the charging and discharging of the electrode assembly 10. Exemplarily, at least a portion of the electrode terminal 30 is exposed to the outside of the battery cell 6 to facilitate connection with other components (such as a busbar component) to further lead out the electrical energy generated by the electrode assembly 10.

[0093] Exemplarily, the electrode terminal 30 may be disposed on the end cover 22 or on the housing 21 .

[0094] In some embodiments, the electrode assembly 10 includes a main body 11 and a tab 12. Exemplarily, the main body 11 may include a portion of the positive electrode sheet coated with an active material layer, a portion of the negative electrode sheet coated with an active material layer, and a separator. The active material in the active material layer is used to electrochemically react with an electrolyte, etc. to generate a charge and discharge process.

[0095] In some embodiments, a plurality of tabs 12 may be provided. The plurality of tabs 12 include a positive tab and a negative tab, and the positive tab and the negative tab may be led out from the same end of the main body 11, or may be led out from opposite ends of the main body 11. Exemplarily, there may be two electrode terminals 30, and the two electrode terminals 30 are electrically connected to the positive tab and the negative tab, respectively.

[0096] In some embodiments, the tab 12 extends from one end of the body 11 facing the electrode terminal 30 .

[0097] In some examples, the two electrode terminals 30 are located on the same side of the main body 11, and the positive electrode tab and the negative electrode tab extend from the same end of the main body 11. In other examples, the two electrode terminals 30 are located on both sides of the main body 11, the positive electrode tab extends from one end of the main body 11 facing one electrode terminal 30, and the negative electrode tab extends from one end of the main body 11 facing the other electrode terminal 30.

[0098] In some embodiments, the tab 12 includes multiple tab layers, which are stacked to increase the current capacity of the tab 12, reduce the heat generated by the tab 12, and reduce the risk of the tab 12 fusing.

[0099] Exemplarily, the tab layer is a metal foil, and the surface of the metal foil is not coated with an active material layer.

[0100] Exemplarily, the tab layer of the positive tab is aluminum foil, and the tab layer of the negative tab is copper foil.

[0101] In some embodiments, the end cap 22 is provided with an electrode lead-out hole, which penetrates the end cap 22 along the thickness direction of the end cap 22. The electrode terminal 30 passes through the electrode lead-out hole. Exemplarily, the battery cell 6 further includes a terminal plate 50, which is located on the outside of the end cap 22, and the portion of the electrode terminal 30 extending outside the end cap 22 is riveted to the terminal plate 50. Exemplarily, the terminal plate 50 is used to connect to an external busbar.

[0102] In some embodiments, the battery cell 6 includes a housing 20, an electrode terminal 30, an electrode assembly 10, and a connecting piece 40. The electrode terminal 30 is disposed in the housing 20. The electrode assembly 10 is accommodated in the housing 20, and the electrode assembly 10 includes a main body 11 and a tab 12, and the tab 12 extends from one end of the main body 11 facing the electrode terminal 30. The connecting piece 40 is welded to the tab 12 to form a first welding portion W1, and the connecting piece 40, the tab 12, and the electrode terminal 30 are welded to form a second welding portion W2.

[0103] In some examples, the first welding portion W1 and the second welding portion W2 may be directly connected. For example, during the operation of the battery cell 6 , the current on the tab 12 may be conducted to the electrode terminal 30 through the first welding portion W1 and the second welding portion W2 .

[0104] In other examples, the first welding portion W1 and the second welding portion W2 are spaced a certain distance apart, and the two are connected by a portion of the connecting sheet 40. For example, during the operation of the battery cell 6, a portion of the current on the pole tab 12 is conducted to the electrode terminal 30 through the second welding portion W2, and another portion of the current on the pole tab 12 can be conducted to the electrode terminal 30 via the first welding portion W1, the connecting sheet 40, and the second welding portion W2.

[0105] The number of the first welding part W1 may be one or more, and the number of the second welding part W2 may be one or more.

[0106] The first welding portion W1 and the second welding portion W2 may be formed by the same welding process or by different welding processes.

[0107] In some examples, at least a portion of the connecting piece 40 is disposed between the pole tab 12 and the electrode terminal 30 and welded to the pole tab 12 and the electrode terminal 30 ; in other examples, at least a portion of the pole tab 12 is disposed between the connecting piece 40 and the electrode terminal 30 and welded to the connecting piece 40 and the electrode terminal 30 .

[0108] The area of ​​the first welding portion W1 may be greater than, equal to, or smaller than the area of ​​the second welding portion W2 .

[0109] Through the first welding portion W1 and the second welding portion W2, multiple conductive paths can be formed between the pole tab 12 and the electrode terminal 30, thereby improving the current flow capacity between the pole tab 12 and the electrode terminal 30 and reducing heat generation. Compared with the second welding portion W2, the formation of the first welding portion W1 is irrelevant to the electrode terminal 30, and the first welding portion W1 has less influence on the pole tab 12 (for example, the pole tab 12 is subjected to less thermal stress), and the portion of the pole tab 12 close to the first welding portion W1 is not easy to tear; when the battery cell 6 is subjected to external impact, even if the portion of the pole 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, thereby reducing the risk of failure of the connection between the pole tab 12 and the electrode terminal 30 and improving the reliability of the battery cell 6.

[0110] In some embodiments, the portion of the tab 12 that is not welded to other components is directly connected to the first welding portion W1. Exemplarily, multiple tab layers of the tab 12 are directly connected to the first welding portion W1. Exemplarily, the thickness of the tab layer is 2 μm-30 μm. Optionally, the thickness of the tab layer is 5 μm-15 μm.

[0111] In some embodiments, the first welding portion W1 is directly connected to the second welding portion W2 .

[0112] Exemplarily, the first welding portion W1 is disposed along the outer circumference of the second welding portion W2. For example, the first welding portion W1 may extend along the outer circumference of the second welding portion W2 by 0.25, 0.5, 0.75 or 1 turn.

[0113] 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 , thereby shortening the conductive path, reducing resistance, improving the current flow capacity, and reducing heat generation.

[0114] In some embodiments, in the extension direction of the electrode tab 12 , at least a portion of the first welding portion W1 is located between the root portion 123 of the electrode tab 12 and the second welding portion W2 .

[0115] Exemplarily, the tab 12 extends outward from the end surface of the main body 11 , and a portion of the tab 12 close to the end surface of the main body 11 may be a root 123 of the tab 12 .

[0116] The current generated by the main body 11 flows to the first welding portion W1 and the second welding portion W2 through the root 123 of the pole tab 12; when the battery cell 6 is subjected to external impact, even if the portion of the pole tab 12 close to the second welding portion W2 is torn, the current can be conducted to the electrode terminal 30 via the root 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 123 of the pole tab 12 and the second welding portion W2, which can reduce the current flowing to the side of the second welding portion W2 of the pole tab 12 away from the root 123, thereby shortening the conductive path, reducing heat generation, and improving the current carrying capacity.

[0117] In some embodiments, at least a portion of the first welding portion W1 is disposed around the second welding portion W2 , which can reduce the distance difference between different portions of the first welding portion W1 and the second welding portion W2 , improve the uniformity of the flow, and reduce heat generation.

[0118] In some embodiments, the outer periphery of the second welding portion W2 is directly connected to the first welding portion W1 to increase the flow area between the first welding portion W1 and the second welding portion W2, reduce resistance, shorten the conductive path, improve flow capacity, and reduce heat generation.

[0119] Exemplarily, the first weld portion W1 separates the second weld portion W2 from the tab layer to reduce the risk of tearing of the tab layer.

[0120] In other embodiments, the first welding portion W1 surrounds the second welding portion W2 and is spaced apart from the second welding portion W2. When the main body 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.

[0121] In some embodiments, in the thickness direction Z of the connecting sheet 40, the projected area of ​​the first welding portion W1 is greater than or equal to 0.2 times the projected area of ​​the second welding portion W2, so as to improve the current flow 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.

[0122] For example, the area of ​​the second welding portion W2 can be set according to the requirements of the battery cell 6 for the overcurrent area. In other words, under normal circumstances, even without the first welding portion W1, the area of ​​the second welding portion W2 can meet the overcurrent requirements. The first welding portion W1 is provided, and the projection area of ​​the first welding portion W1 is set to be greater than or equal to 0.2 times the projection area of ​​the second welding portion W2, so as to meet the overcurrent requirements when unexpected situations such as the tab 12 is torn occur.

[0123] In some embodiments, the thickness of the connecting sheet 40 is 0.1 mm-1.5 mm. As an example, the thickness of the connecting sheet 40 can be 0.1 mm, 0.2 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm or 1.5 mm.

[0124] Limiting the thickness of the connecting sheet 40 to be greater than or equal to 0.1 mm can improve the strength of the connecting sheet 40 and reduce the risk of the connecting sheet 40 tearing; limiting the thickness of the connecting sheet 40 to be less than or equal to 1.5 mm can reduce the difficulty of welding, reduce welding heat generation, reduce thermal stress on the tab 12, and reduce the risk of the tab 12 tearing.

[0125] In some embodiments, the thickness of the connecting sheet 40 is 0.2 mm-0.8 mm.

[0126] In some embodiments, the electrode terminal 30 is an integral structure. A portion of the electrode terminal 30 is located inside the end cap 22 and welded to the connecting piece 40 and the tab 12 . Another portion of the electrode terminal 30 is located outside the end cap 22 and riveted to the terminal plate 50 .

[0127] In some embodiments, the connecting sheet 40 and the tab 12 are connected by ultrasonic welding to form a first welding portion W1. During ultrasonic welding, the tab 12 is less affected by heat; after welding, the portion of the tab 12 near the first welding portion W1 is not easily torn.

[0128] In some embodiments, the connecting piece 40, the tab 12 and the electrode terminal 30 are connected by laser welding to form the second welding portion W2. Laser welding can reduce the welding difficulty and improve the strength of the second welding portion W2 formed by welding.

[0129] In some embodiments, in the thickness direction Z of the connecting sheet 40, at least a portion of the connecting sheet 40 is located between the electrode terminal 30 and the pole tab 12, and is respectively welded to the pole tab 12 and the electrode terminal 30. Specifically, a portion of the connecting sheet 40 located between the electrode terminal 30 and the pole tab 12 is welded to the pole tab 12 and forms a first welding portion W1, and a portion of the connecting sheet 40 located between the electrode terminal 30 and the pole tab 12 is welded to the pole tab 12 and the electrode terminal 30 and forms a second welding portion W2.

[0130] The connection sheet 40 is disposed between the electrode tab 12 and the electrode terminal 30 , so that the risk of interference between the connection sheet 40 and the electrode tab 12 can be reduced during the bending process of the electrode tab 12 .

[0131] In some embodiments, the tab 12 includes a stacking section 121 and a bending section 122, the stacking section 121 is bonded to the connecting sheet 40 in the thickness direction Z, and the bending section 122 is bent from one end of the stacking section 121 and connected to the main body 11. The stacking section 121 is welded to the connecting sheet 40 to form a first welding portion W1, and the connecting sheet 40, the stacking section 121 and the electrode terminal 30 are welded to form a second welding portion W2.

[0132] By bending the electrode tab 12 , the space occupied by the electrode tab 12 in the thickness direction Z can be reduced, thereby improving space utilization.

[0133] In some embodiments, the bent section 122 is bent from one end of the stacked section 121 along the first direction Y. Exemplarily, the first direction Y is perpendicular to the thickness direction Z. Exemplarily, the first direction Y may be parallel to the width direction of the end cap.

[0134] In some embodiments, a portion of the connecting piece 40 does not overlap with the stacking section 121 in the thickness direction Z. The connecting piece 40 has a larger size, so that when welding the connecting piece 40 and the stacking section 121, the risk of cold welding can be reduced and the connection strength can be improved; in addition, when welding the stacking section 121, the connecting piece 40 and the electrode terminal 30, a portion of the connecting piece 40 may not be blocked by the stacking section 121, thereby facilitating the positioning of the connecting piece 40, improving the welding accuracy, and reducing the risk of cold welding.

[0135] In some embodiments, in the first direction Y, the size of the connecting sheet 40 is larger than the size of the stacking segment 121 .

[0136] In the first direction Y, the connecting piece 40 has a larger size, so that when welding the connecting piece 40 and the stacking section 121 , the risk of cold welding can be reduced and the connection strength can be improved.

[0137] In some embodiments, the stacking section 121 includes a first edge 121a, and the first edge 121a is located at an end of the stacking section 121 away from the bending section 122. A portion of the connecting piece 40 extends beyond the first edge 121a.

[0138] The portion of the connecting piece 40 that exceeds the first edge 121a is exposed. When welding the electrode tab 12, the connecting piece 40 and the electrode terminal 30, the portion of the connecting piece 40 that exceeds the first edge 121a can be used for positioning, thereby improving welding accuracy and reducing the risk of cold welding.

[0139] In some embodiments, the stacking section 121 includes two second edges 121b, which are arranged opposite to each other and connected to the first edge 121a. In the arrangement direction of the two second edges 121b, the two second edges 121b are both beyond the connecting piece 40. In the arrangement direction of the two second edges 121b, the connecting piece 40 may have a size smaller than that of the stacking section 121, thereby saving space and improving energy density.

[0140] In some embodiments, the two second edges 121b are arranged opposite to each other along the second direction X. For example, the first direction Y, the second direction X and the thickness direction Z are perpendicular to each other. Optionally, the second direction X is parallel to the length direction of the end cap.

[0141] In some embodiments, the electrode terminal 30 has an inner surface 31 facing the connecting piece 40, and the inner surface 31 is in contact with the connecting piece 40 in the thickness direction Z. The stacking section 121 includes two second edges 121b arranged opposite to each other; in the arrangement direction of the two second edges 121b, both ends of the connecting piece 40 exceed the inner surface 31, and the two second edges 121b exceed the connecting piece 40. The connecting piece 40 can cover the electrode terminal 30 as much as possible, thereby reducing the risk of cold welding and improving the contact area and connection strength between the connecting piece 40 and the electrode terminal 30. In the arrangement direction of the two second edges 121b, the portion of the connecting piece 40 that exceeds the electrode terminal 30 will not be connected to the electrode terminal 30, so the connecting piece 40 can have a size smaller than the stacking section 121, thereby saving space and improving energy density.

[0142] In some embodiments, in the second direction X, the size of the connecting piece 40 is smaller than the size of the stacking section 121 and larger than the size of the electrode terminal 30. In the second direction X, the size of the connecting piece 40 is larger than the size of the electrode terminal 30, so that the connecting piece 40 can cover the electrode terminal 30 as much as possible, reducing the risk of cold welding. In the second direction X, the portion of the connecting piece 40 that exceeds the electrode terminal 30 will not be connected to the electrode terminal 30, so the connecting piece 40 can have a size smaller than the stacking section 121, thereby saving space and improving energy density.

[0143] In some embodiments, the root portion 123 connects the bending segment 122 and the main body 11 .

[0144] In some embodiments, the positive electrode tab and the negative electrode tab extend from two ends of the main body 11 , respectively.

[0145] In some embodiments, the second welding portion W2 is strip-shaped, and the second welding portion W2 extends along the second direction X.

[0146] Optionally, there are a plurality of second welding portions W2 , and the plurality of second welding portions W2 are arranged at intervals along the first direction Y. The outer periphery of each second welding portion W2 is directly connected to the first welding portion W1 .

[0147] In some embodiments, the first welding portion W1 and the second welding portion W2 constitute a welding portion. The size of the second welding portion W2 along the second direction X is L1, the size of the welding portion along the second direction X is L2, and the size of the connecting piece 40 along the second direction X is L3, L3≥L2≥L1.

[0148] The dimension of the second welding portion W2 along the first direction Y is W1, and the dimension of the welding portion along the first direction Y is W2, W2≥W1. The dimension of the connecting piece 40 along the first direction Y is greater than W2.

[0149] In some embodiments, the connecting piece 40 is rectangular.

[0150] In some embodiments, the battery cell 6 can be assembled according to the following steps: first, the pole tab 12 and the connecting sheet 40 are ultrasonically welded to form an ultrasonic weld mark; then, the connecting sheet 40 is attached to the electrode terminal 30; then, a laser is irradiated on the ultrasonic weld mark from the pole tab 12 side, and the laser melts a part of the ultrasonic weld mark and a part of the electrode terminal 30 to form a molten pool, and the molten pool solidifies to form a second weld portion W2 (i.e., a laser weld mark). The remaining part of the ultrasonic weld mark (i.e., the part not melted by the laser irradiation) forms the first weld portion W1.

[0151] When the laser is irradiated, the laser acts on the ultrasonic welding mark, which can reduce the thermal influence on the unwelded part of the tab 12.

[0152] Exemplarily, the dimension of the ultrasonic welding mark along the first direction Y is W2, and the dimension of the ultrasonic welding mark along the second direction X is L2.

[0153] In some embodiments, in the thickness direction Z of the connecting sheet 40 , the projection area of ​​the ultrasonic weld mark is greater than or equal to 1.2 times the projection area of ​​the second welding portion W2 .

[0154] In other embodiments, the battery cell 6 can be assembled according to the following steps: first, the pole tab 12 and the connecting sheet 40 are ultrasonically welded to form an ultrasonic weld mark (i.e., the first weld portion W1); then, the connecting sheet 40 is attached to the electrode terminal 30; then, a laser is irradiated from the pole tab 12, and the laser avoids the ultrasonic weld mark. The laser melts a portion of the pole tab 12, a portion of the connecting sheet 40, and a portion of the electrode terminal 30 to form a molten pool, and after the molten pool solidifies, a second weld portion W2 (i.e., a laser weld mark) is formed.

[0155] In some other embodiments, the battery cell 6 can be assembled according to the following steps: first, the pole tab 12 and the connecting sheet 40 are ultrasonically welded to form an ultrasonic weld mark; then, the connecting sheet 40 is attached to the electrode terminal 30; the ultrasonic weld mark and the part of the pole tab 12 that has not been ultrasonically welded are irradiated with a laser, and the laser melts a part of the ultrasonic weld mark, a part of the pole tab 12, a part of the connecting sheet 40, and a part of the electrode terminal 30 to form a molten pool, and the molten pool solidifies to form a second weld W2 (i.e., a laser weld mark). The remaining part of the ultrasonic weld mark (i.e., the part that is not melted by the laser irradiation) forms the first weld W1.

[0156] In some embodiments, the material of the tab 12 , the material of the connecting sheet 40 , and the material of the electrode terminal 30 are the same.

[0157] According to some embodiments of the present application, the present application further provides a battery, comprising a plurality of battery cells 6 according to any one of the above embodiments.

[0158] According to some embodiments of the present application, the present application further provides an electric device, including a battery cell 6 of any of the above embodiments, the battery cell 6 is used to provide electric energy for the electric device. The electric device can be any of the above equipment or systems using the battery cell 6.

[0159] Reference Figures 3 to 8 The embodiment of the present application provides a battery cell 6, which includes a housing 20, an electrode terminal 30, an electrode assembly 10 and a connecting piece 40. The electrode terminal 30 is disposed in the housing 20. The electrode assembly 10 is accommodated in the housing 20, and the electrode assembly 10 includes a main body 11 and a tab 12, and the tab 12 extends from one end of the main body 11 facing the electrode terminal 30. At least part of the connecting piece 40 is located between the tab 12 and the electrode terminal 30.

[0160] The connecting piece 40 and the tab 12 are connected by ultrasonic welding to form a first welding portion W1. The connecting piece 40, the tab 12 and the electrode terminal 30 are connected by laser welding to form a second welding portion W2. The second welding portion W2 is surrounded by the first welding portion W1, and the outer periphery of the second welding portion W2 is directly connected to the first welding portion W1.

[0161] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may 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, characterized in that: include: shell; An electrode terminal, disposed on the housing; An electrode assembly is contained 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 with 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, characterized in that: The first welding portion is directly connected to the second welding portion.

3. The battery cell according to claim 1, characterized in that: At least a portion of the first welding portion is disposed around the second welding portion.

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

5. The battery cell according to claim 1, characterized in that: In the thickness direction of the connecting sheet, at least a portion of the connecting sheet is located between the electrode terminal and the electrode tab, and is welded to the electrode tab and the electrode terminal, respectively.

6. The battery cell according to claim 5, characterized in that: The tab comprises a stacking section and a bending section, the stacking section is attached to the connecting sheet 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 the first welding portion, and the connection sheet, the stacked sections, and the electrode terminal are welded to form the second welding portion.

7. The battery cell according to claim 6, characterized in that: In the thickness direction, a portion of the connecting sheet does not overlap with the stacked sections.

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

9. The battery cell according to claim 6 or 7, characterized in that: 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 claim 1, characterized in that: 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 claim 1, characterized in that: In the thickness direction of the connecting sheet, a projection area of ​​the first welding portion is greater than or equal to 0.2 times a projection area of ​​the second welding portion.

12. The battery cell according to claim 1, characterized in that: The connecting piece and the electrode tab are connected by ultrasonic welding to form the first welding portion, and the connecting piece, the electrode tab and the electrode terminal are connected by laser welding to form the second welding portion.

13. The battery cell according to claim 1, characterized in that: The thickness of the connecting sheet is 0.1 mm-1.5 mm.

14. A battery, characterized in that: The invention comprises a plurality of battery cells according to any one of claims 1 to 13.

15. An electrical device, characterized in that: A battery according to claim 14, for providing electrical energy.

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