Battery monomer, battery device and electric device

Abstract

The utility model relates to a battery monomer, a battery device and a power utilization device. The battery monomer comprises an electrode assembly, a connecting sheet and an electrode, wherein the electrode assembly comprises a battery cell main body and a tab connected to the battery cell main body; the connecting sheet and the tab are welded and conductively connected to form a first welding mark; the electrode is conductively connected with the tab and the connecting sheet to form a welding seam; the first welding mark comprises one of an ultrasonic welding mark and a friction stir welding mark, and the welding seam is a laser penetration welding seam; the tab is provided with a first side face facing the electrode, and the orthographic projection of the weld joint on the first side face is located in the orthographic projection of the first welding mark on the first side face. According to the battery monomer, laser welding cracks of the tabs can be reduced, and the size of the tabs can be increased, so that the internal resistance of the tabs is reduced, the overcurrent capability of the tabs is improved, and the problem of insufficient overcurrent of the tabs is solved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to battery cells, battery devices and electrical devices. Background Art

[0002] With the development of battery technology, the performance requirements for batteries are getting higher and higher. Batteries usually draw out the energy of the battery through the tabs. The overcurrent capacity of the tabs affects the current carrying capacity of the battery, which in turn affects the charge and discharge performance of the battery. In related technologies, the tabs are usually formed by stacking multiple single-piece tabs, and the tabs and poles are connected by laser welding. However, directly laser welding the tabs and poles can easily cause welding cracks in the tabs, resulting in an increase in the internal resistance of the tabs and the problem of insufficient overcurrent of the tabs. Utility Model Content

[0003] In view of the above problems, the present application provides a battery cell, a battery device and an electrical device, which can improve the problem of insufficient overcurrent of the tab.

[0004] In a first aspect, the present application provides a battery cell, comprising: an electrode assembly, comprising a battery cell body and a pole ear connected to the battery cell body; a connecting sheet, welded to the pole ear for conductive connection and forming a first weld mark; an electrode, welded to the pole ear and the connecting sheet for conductive connection and forming a weld; wherein the first weld mark comprises one of an ultrasonic welding weld mark and a stir friction welding weld mark, and the weld is a laser penetration welding weld; the pole ear has a first side surface facing the electrode, and the orthographic projection of the weld on the first side surface is located within the orthographic projection of the first weld mark on the first side surface.

[0005] In the technical solution of the embodiment of the present application, by connecting the connecting sheet and the pole ear through ultrasonic welding or stir friction welding to form a first weld mark, and connecting the pole ear, the connecting sheet and the electrode through laser penetration welding to form a weld, and the welding area of ​​the weld is located in the first weld mark, it can reduce the generation of laser welding cracks in the pole ear, and is conducive to increasing the size of the pole ear, thereby reducing the internal resistance of the pole ear, improving the overcurrent capacity of the pole ear, and improving the problem of insufficient overcurrent of the pole ear, which is conducive to improving the charge and discharge performance of the battery cell. It can also improve the stability of the welding structure of the pole ear, the connecting sheet and the electrode, and improve the reliability and safety of the battery cell.

[0006] In some embodiments, the ultrasonic welding weld mark includes a weld roughness formed on the welding working surface of the connecting piece and the pole tab and an anti-slip mesh formed on the welding joint surface of the connecting piece and the pole tab; the stir friction welding weld mark includes an annular welding stripe formed on the welding working surface of the connecting piece and the pole tab; the laser penetration welding weld includes a molten pool, which penetrates the pole tab and the connecting piece and connects to the electrode. In this way, it is beneficial to improve the welding quality, thereby forming a stable welding structure, and it is beneficial to improve the reliability and stability of the welding of the pole tab, the connecting piece and the electrode.

[0007] In some embodiments, the orthographic projection of the first weld print on the first side of the tab is located within the orthographic projection of the connecting piece on the first side of the tab. In this way, when the connecting piece and the tab are welded, the probability of the welding process acting alone on the tab can be reduced, and the risk of causing the tab to crack can be reduced, which is conducive to improving the welding quality of the connecting piece and the tab, and improving the stability of the connection between the connecting piece and the tab.

[0008] In some embodiments, the connecting piece is located between the tab and the electrode. In this way, the connecting piece and the electrode metal are fused together to form a stable welding structure, improve the welding quality, and help improve the reliability and stability of the welding complex of the tab and the connecting piece and the electrode, and help form a good conductive channel between the tab and the electrode, thereby improving the current carrying capacity of the tab.

[0009] In some embodiments, the connecting sheet is located on the side of the tab away from the electrode. In this way, the tab can be pressed by the connecting sheet, so that the tab and the electrode are closely attached and directly welded, which can reduce the gap in the tab, reduce the occurrence of laser welding cracks and cold welding in the tab, and thus improve the current carrying capacity of the tab.

[0010] In some embodiments, the tabs include a plurality of stacked single-piece tabs, and the connecting piece is inserted into the plurality of single-piece tabs. In this way, the connection area between the connecting piece and the tab can be increased, a stable welding structure can be formed, the welding quality can be improved, the reliability and stability of the welding between the connecting piece and the tab can be improved, and the gap in the tab can be reduced, thereby improving the current carrying capacity of the tab.

[0011] In some embodiments, the tab includes a plurality of single-piece tabs stacked together, and the plurality of single-piece tabs are welded together to form a second weld mark, and the second weld mark includes an ultrasonic welding weld mark. In this way, cracking of the tab caused by welding the tab to the connecting sheet can be reduced, the welding quality can be improved, and a good conductive channel can be provided between the tab and the connecting sheet, thereby improving the current carrying capacity of the tab, and further improving the charge and discharge performance of the battery cell.

[0012] In some embodiments, the orthographic projection of the first weld print on the first side of the tab is located within the orthographic projection of the second weld print on the first side of the tab. This is helpful to further reduce the generation of laser welding cracks and cracks in the tab, improve the problem of insufficient overcurrent of the tab, thereby improving the overcurrent capacity of the tab, and further improving the charge and discharge performance of the battery cell.

[0013] In some embodiments, the tabs include two outer monolithic tabs and at least one inner monolithic tab stacked between the two outer monolithic tabs, wherein the thickness of the outer monolithic tab is greater than the thickness of the inner monolithic tab. By increasing the thickness of the outer monolithic tabs and increasing the strength of the outer monolithic tabs, the tabs can be cracked and laser welded during welding can be reduced, which is beneficial to improving welding quality, and can also reduce the internal resistance of the tabs and improve the current carrying capacity of the tabs.

[0014] In some embodiments, the electrode assembly includes a plurality of stacked pole pieces and a separator disposed between two adjacent pole pieces; the pole piece includes a current collector and an active material layer, the active material layer is disposed on the surface of a portion of the current collector, the portion of the current collector not provided with the active material layer protrudes from one side of the portion provided with the active material layer, and the portion of the current collector not provided with the active material layer constitutes a single-piece pole ear; the portion of the pole piece with the active material layer constitutes a battery cell body. Thus, a stacked-type electrode assembly is provided, which can reduce the contact internal resistance between the battery cell body and the pole ear by using a current collector without an active material layer to form a single-piece pole ear, reduce the heat generation of the pole ear, and improve the current-carrying capacity of the pole ear, thereby improving the charge and discharge performance of the battery cell.

[0015] In some embodiments, the two outermost pole pieces of the stacked plurality of pole pieces are single-sided pole pieces, and the surface of the single-sided pole pieces facing the outside of the battery body is not provided with an active material layer. In this way, the volume utilization rate of the electrode assembly can be improved, the volume energy density of the battery cell can be improved, and the amount of active material can be saved, which can reduce costs.

[0016] In a second aspect, the present application provides a battery device, comprising a battery cell in any of the above embodiments.

[0017] In a third aspect, the present application provides an electrical device, which includes the battery device in the above embodiment, and the battery device is used to provide electrical energy; or, the electrical device includes the battery cell in any of the above embodiments, and the battery cell is used to provide electrical energy.

[0018] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0020] Figure 1 This is a schematic diagram of the structure of a vehicle according to some embodiments of the present application.

[0021] Figure 2 Schematic diagram of the exploded structure of a battery device according to some embodiments of the present application.

[0022] Figure 3 This is a schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application.

[0023] Figure 4 This is a schematic diagram of the structure of the electrode assembly, connecting sheet and electrode connection in some embodiments of the present application.

[0024] Figure 5 This is a schematic diagram of the locally enlarged structure of the electrode assembly, connecting sheet and electrode connection in some embodiments of the present application.

[0025] Figure 6 It is a schematic diagram of the locally enlarged structure of the electrode assembly, connecting sheet and electrode connection of other embodiments of the present application.

[0026] Figure 7 It is a schematic diagram of the partially enlarged structure of the electrode assembly, connecting sheet and electrode connection of some other embodiments of the present application.

[0027] Figure 8 This is a schematic diagram of the structure of the connection between the tabs, connecting sheets and electrodes in some embodiments of the present application.

[0028] The reference numerals in the specific implementation manner are as follows:

[0029] 1000, vehicle; 100, battery device; 200, controller; 300, motor;

[0030] 10. Box body; 11. First part; 12. Second part;

[0031] 20. Battery cell; 21. End cap; 22. Shell; 23. Electrode assembly; 231. Cell body; 232. Tab; 2320. Monolithic tab; 2320a. Outer monolithic tab; 2320b. Inner monolithic tab; 2321. First tab; 2322. Second tab; 2323. Second weld mark; 233. Pole piece; 2331. First pole piece; 2332. Second pole piece; 2333. Current collector; 2334. Active material layer; 234. Separator; 24. Electrode; 241. First electrode; 242. Second electrode; 25. Connecting piece; 251. First connecting piece; 252. Second connecting piece; 26. First weld mark; 27. Weld; 28. External insulating member. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0033] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations 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. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein 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 figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0035] In the description of the embodiments of the present application, it needs to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0036] In the description of the embodiments of the present application, the terms "first" and "second" are used only for descriptive purposes to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the embodiments of the present application, "plurality" means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0037] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. 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 article generally indicates that the associated objects before and after are in an "or" relationship.

[0038] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0039] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0040] It should be noted that an element is referred to as being "fixed on" or "disposed on" another element, and it may be directly on the other element or there may be a centered element. An element is considered to be "connected to" another element, and it may be directly connected to the other element or there may be a centered element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the embodiments of the present application are for illustrative purposes only and are not intended to be the only implementation method.

[0041] From the perspective of market development, batteries are increasingly used. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the development of battery technology, the performance requirements for batteries are getting higher and higher. Batteries usually draw out the energy of the battery through the tabs. The current capacity of the tabs affects the current carrying capacity of the battery, which in turn affects the charge and discharge performance of the battery.

[0042] In the related art, the pole ear is usually formed by stacking multiple single-piece pole ears, and the pole ear and the pole are connected by laser welding. Since the thickness of the single-piece pole ear is very thin, for example, the pole ear is usually 13 microns thick aluminum foil or 6 microns thick copper foil, the number of layers of the pole ear is large, for example, 100 layers, and there are gaps between the multiple single-piece pole ears stacked. If the pole ear and the pole are directly laser welded, the laser will melt the single-piece pole ear to form a molten droplet and drip from the gap, which is easy to cause laser welding cracks in the pole ear, resulting in an increase in the internal resistance of the pole ear. When the current passes through the pole ear, it is easier to heat up, which limits the large current passing through the pole ear, resulting in insufficient overcurrent of the pole ear. If the pole ear and the adapter are ultrasonically pre-welded, and then the adapter is laser welded to the pole, although it can reduce the generation of laser welding cracks in the pole ear, it is necessary to reserve an area for laser welding of the adapter and the pole, which limits the size of the pole ear, resulting in a narrow pole ear, limiting the overcurrent capacity of the pole ear, resulting in insufficient overcurrent of the pole ear.

[0043] Based on the above considerations, in order to improve the problem of insufficient overcurrent of the pole ear, the present application designs a battery cell, firstly connects the pole ear and the gasket together by ultrasonic pre-welding to reduce the gap in the pole ear, and then connects the welding complex of the pole ear and the gasket and the pole column by laser penetration welding, and the laser welding area is located in the ultrasonic pre-welding area. Since the gap in the ultrasonic pre-welding area is reduced, the generation of laser welding cracks in the pole ear can be reduced, and the gasket does not need to reserve an area for laser welding with the pole column, the size of the pole ear can be increased, thereby reducing the internal resistance of the pole ear and improving the overcurrent capacity of the pole ear.

[0044] The battery cell disclosed in the embodiment of the present application can be used in, but not limited to, electric devices such as vehicles, ships or aircraft. A power supply system comprising the battery cell and battery device disclosed in the present application can be used to form the electric device, which is helpful to reduce the generation of laser welding cracks in the tabs, and at the same time can increase the size of the tabs and improve the current carrying capacity of the tabs.

[0045] The embodiment of the present application provides an electric device using a battery device as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0046] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device in some embodiments of the present application.

[0047] Please refer to Figure 1 , Figure 1A schematic diagram of the structure of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 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, etc. A battery device 100 is provided inside the vehicle 1000, and the battery device 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery device 100 may be used to power the vehicle 1000, for example, the battery device 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery device 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0048] In some embodiments of the present application, the battery device 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0049] Please refer to Figure 2 , Figure 2 Schematic diagram of the exploded structure of the battery device 100 provided in some embodiments of the present application. The battery device 100 includes a box 10 and a battery cell 20, and the battery cell 20 is contained in the box 10. Among them, the box 10 is used to provide a storage space for the battery cell 20, and the box 10 can adopt a variety of structures. In some embodiments, the box 10 may include a first part 11 and a second part 12, the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space for accommodating the battery cell 20. The second part 12 can be a hollow structure with one end open, the first part 11 can be a plate-like structure, and the first part 11 covers the open side of the second part 12, so that the first part 11 and the second part 12 jointly define a storage space; the first part 11 and the second part 12 can also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the box 10 formed by the first part 11 and the second part 12 can be in a variety of shapes, such as a cylinder, a cuboid, etc.

[0050] In the battery device 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, the battery device 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10. The battery device 100 may also include other structures, for example, the battery device 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.

[0051] Each battery cell 20 may be a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular or in other shapes, that is, the battery cell 20 is not limited to a square-shell battery, but may also be a cylindrical battery.

[0052] Please refer to Figure 3 , Figure 3 The schematic diagram of the exploded structure of the battery cell 20 provided in some embodiments of the present application. The battery cell 20 refers to the smallest unit constituting the battery device 100. Figure 3 The battery cell 20 includes an end cover 21, a shell 22, an electrode assembly 23 and other functional components.

[0053] The end cap 21 refers to a component that covers the opening of the shell 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the shell 22 to match the shell 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 21 is not easily deformed when squeezed and collided, so that the battery cell 20 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrodes 24 can be provided on the end cap 21. The electrode 24 can be used to electrically connect with the electrode assembly 23 for outputting or inputting electrical energy of the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The material of the end cap 21 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this. In some embodiments, an insulating member may be provided inside the end cap 21, and the insulating member may be used to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be plastic, rubber, or the like.

[0054] The shell 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 23, the electrolyte and other components. The shell 22 and the end cap 21 can be independent components, and an opening can be set on the shell 22, and the internal environment of the battery cell 20 is formed by covering the opening with the end cap 21 at the opening. Without limitation, the end cap 21 and the shell 22 can also be integrated. Specifically, the end cap 21 and the shell 22 can form a common connection surface before other components are put into the shell, and when the interior of the shell 22 needs to be encapsulated, the end cap 21 covers the shell 22. The shell 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the shell 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0055] The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 23 may be included in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the battery cell body 231, and the positive and negative electrode sheets are each connected to a pole ear 232. The two pole ears 232 may be located together at one end of the battery cell body 231 or respectively at both ends of the battery cell body 231. During the charge and discharge process of the battery cell 20, the positive electrode active material and the negative electrode active material react with the electrolyte, and the pole ear 232 connects the electrode 24 to form a current loop.

[0056] The battery cell 20 may further include an external insulating member 28, which may wrap the electrode assembly 23, and may space the shell 22 and the electrode assembly 23 to achieve insulation protection for the electrode assembly 23. The external insulating member 28 may include an insulating film, which may be folded to form a top-opening box body that is substantially the same shape as the shell 22, but slightly smaller in size. For example, the shell 22 is in the shape of a rectangular parallelepiped, and the external insulating member 28 is folded to form a top-opening rectangular box body that is adapted to the size of the electrode assembly 23; the electrode assembly 23 is first loaded into the folded external insulating member 28, and then loaded into the shell 22 together with the external insulating member 28, so that the external insulating member 28 spaces the electrode assembly 23 from the shell 22. The external insulating member 28 may be made of PP (polypropylene) or PET (polyethylene terephthalate), such as Mylar, a tough polyester polymer that has good heat resistance, excellent electrical insulation, and even good electrical performance at high temperature and high frequency.

[0057] According to some embodiments of the present application, referring to Figure 3 , and please refer to Figures 4 to 8 , Figure 4 This is a schematic diagram of the structure of the connection between the electrode assembly 23, the connecting sheet 25 and the electrode 24 in some embodiments of the present application. Figure 5 This is a partial enlarged structural diagram of the connection between the electrode assembly 23, the connecting sheet 25 and the electrode 24 in some embodiments of the present application. Figure 6 It is a partial enlarged structural schematic diagram of the connection between the electrode assembly 23, the connecting sheet 25 and the electrode 24 in some other embodiments of the present application, Figure 7 This is a partial enlarged structural diagram of the connection between the electrode assembly 23, the connecting sheet 25 and the electrode 24 in some other embodiments of the present application. Figure 8 The present invention is a schematic diagram of the structure of the connection between the pole ear 232, the connecting sheet 25 and the electrode 24 in some embodiments of the present application. The present application provides a battery cell 20. The battery cell 20 includes an electrode assembly 23, a connecting sheet 25 and an electrode 24. The electrode assembly 23 includes a battery cell body 231 and a pole ear 232 connected to the battery cell body 231. The connecting sheet 25 is welded and conductively connected to the pole ear 232 to form a first weld mark 26. The electrode 24 is welded and conductively connected to the pole ear 232 and the connecting sheet 25 to form a weld 27. Among them, the first weld mark 26 includes one of an ultrasonic welding weld mark and a stir friction welding weld mark, and the weld 27 is a laser penetration welding weld; the pole ear 232 has a first side facing the electrode 24, and the orthographic projection of the weld 27 on the first side is located within the orthographic projection of the first weld mark 26 on the first side.

[0058] As shown in the figure, the Y direction in the figure is the height direction of the electrode assembly 23, the X direction is the width direction of the electrode assembly 23, and the Z direction is the thickness direction of the electrode assembly 23.

[0059] The electrode assembly 23 may be a unit formed by winding or stacking a laminated monomer, wherein the laminated monomer includes a first electrode 2331, a separator 234, and a second electrode 2332. When the first electrode 2331 is a positive electrode, the second electrode 2332 is a negative electrode. The polarities of the first electrode 2331 and the second electrode 2332 may be interchangeable. The battery cell body 231 may be a portion of the first electrode 2331 and the second electrode 2332 having active materials.

[0060] The pole tab 232 may include at least two single-piece pole tabs 2320 stacked in layers. The single-piece pole tab 2320 may be a metal sheet. The metal sheet may be a part of the current collector 2333 or may be prepared separately, which is not specifically limited here. The pole tab 232 may have at least one first pole tab 2321 and at least one second pole tab 2322. The single-piece pole tab 2320 of the first pole tab 2321 is connected to the first pole sheet 2331, and the single-piece pole tab 2320 of the second pole tab 2322 is connected to the second pole sheet 2332. When the first pole sheet 2331 is a positive electrode and the second pole sheet 2332 is a negative electrode, the first pole tab 2321 is a positive pole tab and the second pole tab 2322 is a negative pole tab. The first pole tab 2321 and the second pole tab 2322 may be located together at one end of the height direction Y of the battery cell body 231 or at both ends of the height direction Y of the battery cell body 231. The first pole ear 2321 and the second pole ear 2322 can be made of different metals, such as the positive pole ear can be made of aluminum and the negative pole ear can be made of copper. In other different battery chemical systems, the first pole ear 2321 and the second pole ear 2322 can also be made of the same metal, such as the first pole ear 2321 and the second pole ear 2322 are both made of aluminum.

[0061] The electrode 24 is made of a conductive material, and the electrode 24 is connected to the pole ear 232 to form a current loop. The input and output of electric energy are realized through the electrode 24, so that the electrode assembly 23 is charged and discharged through the electrode 24. The material of the electrode 24 can be, but not limited to, copper, aluminum, etc. The shape of the electrode 24 can be, but not limited to, a cylinder, a prism, etc. The electrode 24 can include a first electrode 241 and a second electrode 242, the first electrode 241 is connected to the first pole ear 2321, and the second electrode 242 is connected to the second pole ear 2322. The first electrode 241 and the second electrode 242 can be arranged on the end cover 21 of the battery cell 20, or the first electrode 241 and the second electrode 242 can be arranged on the shell 22 of the battery cell 20, or one of the first electrode 241 and the second electrode 242 can be arranged on the end cover 21, and the other can be arranged on the shell 22.

[0062] The connecting piece 25 is welded together with the pole lug 232 and the electrode 24 to electrically connect the connecting piece 25, the pole lug 232 and the electrode 24. The material of the connecting piece 25 matches the material of the corresponding pole lug 232 to which the welding connection is connected. The connecting piece 25 can be of various shapes and sizes, such as rectangular, square, L-shaped, Z-shaped, irregular shape, etc. The thickness of the connecting piece 25 is greater than the thickness of the single-piece pole lug 2320. In some embodiments, the thickness of the connecting piece 25 can range from 0.01 mm to 10 mm. The connecting piece 25 includes at least one first connecting piece 251 and at least one second connecting piece 252, the first connecting piece 251 is welded to the first pole lug 2321 and the first electrode 241, and the second connecting piece 252 is welded to the second pole lug 2322 and the second electrode 242.

[0063] The first weld mark 26 refers to a welding structure formed by welding the connecting piece 25 and the pole lug 232, and the first weld mark 26 is located at the connection position between the connecting piece 25 and the pole lug 232. The ultrasonic welding weld mark is a weld mark formed by ultrasonic welding the connecting piece 25 and the pole lug 232. The stir friction welding weld mark is a weld mark formed by stir friction welding the connecting piece 25 and the pole lug 232. Both ultrasonic welding and stir friction welding can fuse the metals of the pole lug 232 and the connecting piece 25 together, and welding cracks are not easy to occur. At the same time, when ultrasonic welding or stir friction welding is performed on the connecting piece 25 and the pole lug 232, multiple single-piece pole lugs 2320 can be pressed together so that adjacent single-piece pole lugs 2320 are in contact, thereby reducing the gap in the first weld mark 26. The above-mentioned ultrasonic welding and stir friction welding are both existing technologies and will not be repeated here.

[0064] The weld 27 refers to a welded structure formed by welding the pole tab 232, the connecting piece 25 and the electrode 24. The laser penetration welding weld is a weld 27 formed by laser penetration welding the electrode 24, the pole tab 232 and the connecting piece 25. The laser penetration welding can fuse the pole tab 232, the connecting piece 25 and the electrode 24 metal together, realize the welding connection of the pole tab 232, the connecting piece 25 and the electrode 24, and thus form a stable welding structure. The above-mentioned laser penetration welding is a prior art and will not be repeated here.

[0065] At the same time, the pole tab 232 has a first side facing the electrode 24, and the orthographic projection of the weld 27 on the first side of the pole tab 232 is located within the orthographic projection range of the first weld mark 26 on the first side of the pole tab 232, that is, the welding area when the electrode 24, the pole tab 232 and the connecting piece 25 are laser-penetrated and welded is located within the first weld mark 26 formed by ultrasonic welding or friction stir welding of the connecting piece 25 and the pole tab 232. Since the gap in the first weld mark 26 is reduced, the problem of laser welding cracks in the pole tab 232 can be reduced by laser-penetrating and welding the pole tab 232, the connecting piece 25 and the electrode 24 in the first weld mark 26, thereby reducing the internal resistance of the pole tab 232. In addition, the pole tab 232, the connecting piece 25 and the electrode 24 are laser-penetrated and welded in one piece, and the connecting piece 25 does not need to reserve an area for laser welding with the electrode 24, and the pole tab 232 can overlap with the connecting piece 25 or even cover the connecting piece 25, thereby increasing the size of the pole tab 232 and reducing the internal resistance of the pole tab 232. In this way, the current carrying capacity of the tab 232 is improved, which is beneficial to improving the charge and discharge performance of the battery cell 20 .

[0066] For example, the process of welding the tab 232, the connecting piece 25 and the electrode 24 may be:

[0067] The connecting piece 25 and the pole ear 232 are pre-welded together by ultrasonic welding or friction stir welding, and a first weld mark 26 is formed on the pole ear 232 and the connecting piece 25 to obtain a welded complex of the pole ear 232 and the connecting piece 25;

[0068] The welding complex of the pole lug 232 and the connecting piece 25 is placed on the electrode 24, and the pole lug 232, the connecting piece 25 and the electrode 24 are welded together by laser penetration welding, and the welding area of ​​the laser penetration welding is located within the first weld mark 26 to form a weld 27 on the pole lug 232, the connecting piece 25 and the electrode 24, thereby completing the welding connection of the pole lug 232, the connecting piece 25 and the electrode 24.

[0069] The battery cell 20 of the embodiment of the present application connects the connecting piece 25 and the pole ear 232 by ultrasonic welding or stir friction welding to form a first weld mark 26, and at the same time connects the pole ear 232, the connecting piece 25 and the electrode 24 by laser penetration welding to form a weld 27, and the weld 27 is located in the first weld mark 26, which can reduce the generation of laser welding cracks in the pole ear 232, and is conducive to increasing the size of the pole ear 232, thereby reducing the internal resistance of the pole ear 232, improving the current capacity of the pole ear 232, and improving the problem of insufficient current of the pole ear 232, which is conducive to improving the charge and discharge performance of the battery cell 20. In addition, the welding structure stability of the pole ear 232, the connecting piece 25 and the electrode 24 can be improved, and the reliability and safety of the battery cell 20 can be improved.

[0070] In some embodiments, the ultrasonic welding mark includes a welding rough surface formed on the welding working surface where the connecting piece 25 is welded to the pole tab 232 and an anti-slip mesh pattern formed on the welding joint surface where the connecting piece 25 is welded to the pole tab 232 .

[0071] The welding working surface for welding the connecting piece 25 and the pole tab 232 refers to the working surface of the welding equipment when welding the connecting piece 25 and the pole tab 232. For example, the welding working surface for welding the connecting piece 25 and the pole tab 232 can be the side surface of the pole tab 232 facing away from the connecting piece 25. The welding joint surface for welding the connecting piece 25 and the pole tab 232 refers to the side surface where the connecting piece 25 and the pole tab 232 are connected.

[0072] Ultrasonic welding uses high-frequency vibration waves to be transmitted to the metal surface to be welded, and under pressure, the two metal surfaces are rubbed against each other to form a fusion between the molecular layers. During the ultrasonic welding process, due to the vibration of the high-frequency vibration wave, a large number of densely distributed protrusions are formed on the welding working surface where the connecting piece 25 and the pole lug 232 are welded, thereby forming a welding rough surface on the welding working surface where the connecting piece 25 and the pole lug 232 are welded. An anti-slip mesh is provided on the welding joint surface where the connecting piece 25 and the pole lug 232 are welded. For example, the anti-slip mesh can be provided on the side surface of the connecting piece 25 facing the pole lug 232. In some embodiments, the anti-slip mesh can be a grid-like tooth mark, and the shape of the anti-slip mesh can be square, diamond or strip, etc. The anti-slip mesh is used to reduce the relative sliding between the connecting piece 25 and the pole lug 232, so as to transfer energy to the welding position as much as possible, which is conducive to improving the welding quality.

[0073] In some embodiments, the friction stir welding weld mark includes annular welding lines formed on the welding working surface where the connecting piece 25 and the tab 232 are welded.

[0074] Friction stir welding utilizes the heat generated by the friction between a high-speed rotating welding tool and the material to be welded to partially melt the material to be welded. The welding tool rotates at high speed while moving relative to the material to be welded. The plasticized material flows from the front to the rear of the welding tool under the action of the rotating friction force of the welding tool, and forms a dense solid phase weld under the extrusion of the welding tool, thereby forming annular welding stripes on the welding working surface where the connecting piece 25 and the pole ear 232 are welded.

[0075] In some embodiments, the laser penetration welding weld includes a molten pool that penetrates the tab 232 and the connecting piece 25 and connects to the electrode 24 .

[0076] Laser penetration welding belongs to fusion welding. The molten pool refers to the liquid metal part with a certain shape formed on the material to be welded under the action of the heat source during fusion welding, and the partial structure formed after solidification. Since the molten pool penetrates the pole ear 232 and the connecting piece 25 and connects to the electrode 24, the metals of the pole ear 232, the connecting piece 25 and the electrode 24 are fused together, thereby forming a stable welding structure, which is conducive to improving the reliability and stability of the welding of the pole ear 232, the connecting piece 25 and the electrode 24.

[0077] In some embodiments, reference Figure 8 The orthographic projection of the first weld mark 26 on the first side surface of the pole ear 232 is located within the orthographic projection of the connecting piece 25 on the first side surface of the pole ear 232 .

[0078] It can be understood that when welding the connecting piece 25 and the tab 232 , the welding area does not exceed the connecting piece 25 .

[0079] In this way, when the connecting piece 25 and the pole lug 232 are welded together, the probability of the welding process acting alone on the pole lug 232 can be reduced, and the risk of causing the pole lug 232 to crack can be reduced, which is beneficial to improving the welding quality of the connecting piece 25 and the pole lug 232 and improving the stability of the connection between the connecting piece 25 and the pole lug 232.

[0080] In some embodiments, reference Figure 5 The connecting piece 25 is located between the electrode tab 232 and the electrode 24 .

[0081] When pre-welding the connecting piece 25 and the pole tab 232, the connecting piece 25 can be welded to the side of the pole tab 232 facing the electrode 24. Therefore, when laser penetration welding is performed on the electrode 24, the pole tab 232 and the connecting piece 25, the connecting piece 25 is in direct contact with the electrode 24, and the pole tab 232 is laser penetration welded with the electrode 24 through the connecting piece 25.

[0082] In this way, the metals of the connecting piece 25 and the electrode 24 are fused together to form a stable welding structure, which improves the welding quality, is beneficial to improving the reliability and stability of the welding complex of the pole ear 232 and the connecting piece 25 and the electrode 24, and is beneficial to forming a good conductive channel between the pole ear 232 and the electrode 24, thereby improving the current carrying capacity of the pole ear 232.

[0083] In some embodiments, reference Figure 6 The connecting piece 25 is located on the side of the pole ear 232 facing away from the electrode 24 .

[0084] When pre-welding the connecting piece 25 and the pole ear 232, the connecting piece 25 can be welded to the side of the pole ear 232 away from the electrode 24. When laser penetration welding is performed on the electrode 24, the pole ear 232 and the connecting piece 25, the pole ear 232 can be pressed against the electrode 24 through the connecting piece 25, and the pole ear 232 is in direct contact with the electrode 24.

[0085] In this way, the pole ear 232 can be pressed by the connecting sheet 25 so that the pole ear 232 and the electrode 24 can be directly welded after being tightly fitted, which can reduce the gap inside the pole ear 232 and reduce the laser welding cracks and cold welding of the pole ear 232, thereby improving the current carrying capacity of the pole ear 232.

[0086] In some embodiments, reference Figure 7 The tab 232 includes a plurality of stacked single-piece tabs 2320 , and the connecting piece 25 is inserted into the plurality of single-piece tabs 2320 .

[0087] When pre-welding the connection sheet 25 and the pole tab 232 , the connection sheet 25 may be inserted between the layers of the plurality of single-piece pole tabs 2320 of the pole tab 232 for welding.

[0088] In this way, the connection area between the connecting piece 25 and the pole lug 232 can be increased, a stable welding structure can be formed, the welding quality can be improved, the reliability and stability of the welding between the connecting piece 25 and the pole lug 232 can be improved, and the gap in the pole lug 232 can be reduced, thereby helping to improve the current carrying capacity of the pole lug 232.

[0089] In some embodiments, reference Figures 5 to 8 The tab 232 includes a plurality of single-piece tabs 2320 stacked together, the plurality of single-piece tabs 2320 are welded together to form a second weld mark 2323, and the second weld mark 2323 includes an ultrasonic welding weld mark.

[0090] The second weld mark 2323 refers to a weld structure formed by welding a plurality of stacked single-piece tabs 2320. The second weld mark 2323 includes an ultrasonic welding weld mark. It can be understood that the second weld mark 2323 is a weld mark formed by ultrasonically welding a plurality of single-piece tabs 2320.

[0091] The tabs 232 may be pre-welded between layers first, and multiple single-piece tabs 2320 may be pressed by ultrasonic welding so that adjacent single-piece tabs 2320 are in contact, thereby reducing the interlayer gap in the tabs 232. When pre-welding the tabs 232 between layers, a smaller welding energy may be used to reduce the damage to the single-piece tabs 2320 caused by ultrasonic welding, thereby reducing the cracking of the single-piece tabs 2320. Then, the pre-welded tabs 232 and the connecting piece 25 are pre-welded for a second time. Since multiple single-piece tabs 2320 are stacked more tightly in the pre-welded tabs 232, ultrasonic welding or friction stir welding of the connecting piece 25 and the tabs 232 is not likely to cause cracking of the tabs 232, and the welding energy when welding the tabs 232 and the connecting piece 25 may be increased, which is conducive to forming a stable welding structure, reducing the risk of false welding, improving welding quality, and providing a good conductive channel between the tabs 232 and the connecting piece 25, thereby improving the current carrying capacity of the tabs 232.

[0092] By connecting multiple single-piece pole ears 2320 through the second weld mark 2323, it is helpful to reduce the cracking of the pole ear 232 caused by welding the pole ear 232 and the connecting piece 25, which can improve the welding quality and provide a good conductive channel between the pole ear 232 and the connecting piece 25, thereby improving the current carrying capacity of the pole ear 232 and further improving the charging and discharging performance of the battery cell 20.

[0093] In some embodiments, reference Figure 8 The orthographic projection of the first weld mark 26 on the first side surface of the pole lug 232 is located within the orthographic projection of the second weld mark 2323 on the first side surface of the pole lug 232 .

[0094] That is, the welding area when welding the connecting piece 25 and the pole tab 232 is located in the second weld mark 2323 formed by ultrasonic welding the pole tab 232. Since the second weld mark 2323 reduces the gap in the pole tab 232, the pole tab 232 and the connecting piece 25 are pre-welded for the second time in the second weld mark 2323, which can reduce the cracking of the pole tab 232 and further reduce the gap in the pole tab 232.

[0095] This is beneficial to further reduce the laser welding cracks and splits of the tab 232 , improve the problem of insufficient overcurrent of the tab 232 , thereby improving the overcurrent capacity of the tab 232 , and further improving the charge and discharge performance of the battery cell 20 .

[0096] In some embodiments, reference Figures 5 to 7 The multiple single-piece tabs 2320 of the tab 232 include two outer single-piece tabs 2320a and at least one inner single-piece tab 2320b stacked between the two outer single-piece tabs 2320a, wherein the thickness of the outer single-piece tab 2320a is greater than the thickness of the inner single-piece tab 2320b.

[0097] The outer monolithic tab 2320a is located at the outermost layer of the stacked multiple monolithic tabs 2320. In some embodiments, the thickness D1 of the outer monolithic tab 2320a can be in the range of 50 microns (μ) to 100 microns, that is, 50μ≤D1≤100μ. At least one inner monolithic tab 2320b is clamped between two outer monolithic tabs 2320a. In some embodiments, the thickness D2 of the inner monolithic tab 2320b can be in the range of 1 micron to 50 microns, that is, 1μ≤D2≤50μ, for example, 4μ≤D2≤10μ.

[0098] By increasing the thickness of the outer single-piece pole ear 2320a and increasing the strength of the outer single-piece pole ear 2320a, the cracking of the pole ear 232 and the generation of laser welding cracks during welding can be reduced, which is beneficial to improving the welding quality, and can also reduce the internal resistance of the pole ear 232 and improve the current carrying capacity of the pole ear 232.

[0099] In some embodiments, reference Figures 5 to 7 The electrode assembly 23 includes a plurality of stacked pole pieces 233 and a separator 234 disposed between two adjacent pole pieces 233. The pole piece 233 includes a current collector 2333 and an active material layer 2334. The active material layer 2334 is disposed on the surface of a portion of the current collector 2333. The portion of the current collector 2333 without the active material layer 2334 protrudes from one side of the portion with the active material layer 2334. The portion of the current collector 2333 without the active material layer 2334 constitutes a single-piece pole ear 2320. The portion of the pole piece 233 with the active material layer 2334 constitutes the battery cell body 231.

[0100] The electrode assembly 23 of this embodiment is a laminated battery cell. The multiple stacked pole pieces 233 are independent of each other, and the polarities of any two adjacent pole pieces 233 are different. For example, the multiple pole pieces 233 may include a first pole piece 2331 and a second pole piece 2332. When the first pole piece 2331 is a positive pole piece, the second pole piece 2332 is a negative pole piece. The polarities of the first pole piece 2331 and the second pole piece 2332 can be interchanged. The first pole piece 2331 and the second pole piece 2332 are alternately stacked, and the adjacent first pole pieces 2331 and the second pole pieces 2332 are separated by a separator 234.

[0101] A portion of the current collector 2333 without the active material layer 2334 extends from each pole piece 233 to form a single-piece pole tab 2320. After a plurality of pole pieces 233 are stacked, a plurality of single-piece pole tabs 2320 of the same polarity are stacked in sequence to form a multi-layer pole tab 232. Each pole piece 233 may be connected to at least one single-piece pole tab 2320. For example, a plurality of single-piece pole tabs 2320 extending from a plurality of first pole pieces 2331 are stacked to form a first pole tab 2321, and a plurality of single-piece pole tabs 2320 extending from a plurality of second pole pieces 2332 are stacked to form a second pole tab 2322. In some embodiments, there may be 2 to N first pole pieces 2331 and 1 to N-1 second pole pieces 2332 in the plurality of pole pieces 233, wherein the two first pole pieces 2331 are located at the outermost layer of the electrode assembly 23.

[0102] Among them, the positive electrode sheet includes a positive electrode collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode collector, the positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer, and the positive electrode collector not coated with the positive electrode active material layer constitutes a positive electrode single-piece pole ear. The positive electrode active material can be a ternary material / lithium iron phosphate material + sulfide / halide / oxide / polymer solid electrolyte, etc. Taking lithium-ion batteries as an example, the positive electrode collector can be aluminum foil, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. After the positive electrode active material is stirred and mixed, a positive electrode slurry is obtained, and then the positive electrode slurry is coated on the surface of the positive electrode collector, and after baking and drying, cold pressing (rolling), pre-slitting, slitting and other processes are performed to prepare a positive electrode sheet. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode current collector not coated with the negative electrode active material layer protrudes from the negative electrode current collector coated with the negative electrode active material layer. The negative electrode current collector not coated with the negative electrode active material layer constitutes a negative electrode single-piece pole ear. The negative electrode active material can be silicon-carbon material / non-negative electrode lithium metal / stainless steel material / hard carbon material / nanosilver material, etc. Taking lithium-ion batteries as an example, the negative electrode current collector can be copper foil, and the negative electrode active material can be carbon or silicon, etc. The negative electrode active material is stirred and mixed to obtain a negative electrode slurry, and then the negative electrode slurry is coated on the surface of the negative electrode current collector, and after baking and drying, cold pressing, pre-cutting, slitting, etc. are performed to prepare a negative electrode sheet. The separator 234 can be a diaphragm. The diaphragm can be at least one of glass fiber cloth, non-woven fabric, polypropylene (PP) film and polyethylene (PE) film; the diaphragm can be a single-layer film or a multi-layer composite film, which is not limited here.

[0103] In some embodiments, reference Figures 5 to 7In the stacked structure of the electrode assembly 23, the thickness of the current collector 2333 of the two first pole pieces 2331 located in the outermost layer can be set to be greater than the thickness of the current collector 2333 of the remaining first pole pieces 2331, and the thickness of the current collector 2333 of the two second pole pieces 2332 located in the outermost layer can be set to be greater than the thickness of the current collector 2333 of the remaining second pole pieces 2332. For example, the thickness of the current collector 2333 of the first pole piece 2331 and the second pole piece 2332 located in the outermost layer can be set to be in the range of 50 microns to 100 microns, and the thickness of the current collector 2333 of the remaining first pole piece 2331 and the second pole piece 2332 can be in the range of 1 micron to 50 microns. In this way, the thickness of the outer monolithic pole tab 2320a can be greater than the thickness of the inner monolithic pole tab 2320b.

[0104] In this way, a stacked electrode assembly 23 is provided. By adopting a current collector 2333 without an active material layer 2334 to form a single-piece pole ear 2320, the contact internal resistance between the battery body 231 and the pole ear 232 can be reduced, the heat generation of the pole ear 232 can be reduced, the current flow capacity of the pole ear 232 can be improved, and the charging and discharging performance of the battery cell 20 can be improved.

[0105] In some embodiments, reference Figures 5 to 7 The two outermost pole pieces 233 of the stacked plurality of pole pieces 233 are single-sided pole pieces, and no active material layer 2334 is disposed on the surface of the single-sided pole pieces facing the outside of the battery cell body 231 .

[0106] By eliminating the active material layer 2334 on the surface of the two outermost pole pieces 233 of the stacked battery cell facing the outside of the battery cell body 231, the volume utilization of the electrode assembly 23 can be improved, the volume energy density of the battery cell 20 can be improved, the amount of active material can be saved, and the cost can be reduced.

[0107] According to some embodiments of the present application, the present application further provides a battery device 100, comprising the battery cell 20 provided in any of the above embodiments.

[0108] Since the battery device 100 has the same technical effects as the above-mentioned battery cell 20 , detailed description thereof will be omitted here.

[0109] According to some embodiments of the present application, the present application further provides an electric device. The electric device includes the battery device 100 provided in any of the above embodiments, and the battery device 100 is used to provide electric energy for the electric device. Or the electric device includes the battery cell 20 provided in any of the above embodiments, and the battery cell 20 is used to provide electric energy for the electric device.

[0110] The power-consuming device may be any of the aforementioned devices or systems using the battery device 100. Since the power-consuming device has the same technical effects as the aforementioned battery device 100 and battery cell 20, they will not be described in detail here.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: An electrode assembly, comprising a battery cell body and a tab connected to the battery cell body; A connecting piece, which is welded and electrically connected to the tab to form a first weld mark; An electrode is welded and electrically connected with the electrode tab and the connecting piece to form a weld; Wherein, the first weld mark includes one of an ultrasonic welding weld mark and a stir friction welding weld mark, and the weld is a laser penetration welding weld; the pole ear has a first side facing the electrode, and the orthographic projection of the weld on the first side is located within the orthographic projection of the first weld mark on the first side.

2. The battery cell according to claim 1, characterized in that: The ultrasonic welding mark includes a welding rough surface formed on the welding working surface of the connecting piece and the tab and an anti-slip mesh pattern formed on the welding joint surface of the connecting piece and the tab; The friction stir welding weld mark comprises an annular welding stripe formed on the welding working surface of the connecting piece and the tab; The laser penetration welding weld includes a molten pool, which penetrates the electrode tab and the connecting piece and is connected to the electrode.

3. The battery cell according to claim 1, characterized in that: The orthographic projection of the first weld print on the first side surface of the pole lug is located within the orthographic projection of the connecting piece on the first side surface of the pole lug.

4. The battery cell according to claim 1, characterized in that: The connecting sheet is located between the electrode tab and the electrode; Alternatively, the connecting piece is located on a side of the tab away from the electrode; Alternatively, the electrode tab comprises a plurality of stacked single-piece electrode tabs, and the connecting piece is inserted into the plurality of single-piece electrode tabs.

5. The battery cell according to claim 1, characterized in that: The electrode tabs include a plurality of single-piece electrode tabs stacked together, and the plurality of single-piece electrode tabs are welded together to form a second weld mark, and the second weld mark includes an ultrasonic welding weld mark.

6. The battery cell according to claim 5, characterized in that: The orthographic projection of the first weld print on the first side surface of the pole tab is located within the orthographic projection of the second weld print on the first side surface of the pole tab.

7. The battery cell according to claim 1, characterized in that: The tabs include two outer monolithic tabs and at least one inner monolithic tab stacked between the two outer monolithic tabs, wherein the thickness of the outer monolithic tab is greater than the thickness of the inner monolithic tab.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The electrode assembly comprises a plurality of electrode sheets stacked in layers and a separator disposed between two adjacent electrode sheets; The pole piece includes a current collector and an active material layer, wherein the active material layer is arranged on the surface of a portion of the current collector, the portion of the current collector where the active material layer is not arranged protrudes from one side of the portion where the active material layer is arranged, and the portion of the current collector where the active material layer is not arranged constitutes a single-piece pole ear; the portion of the pole piece with the active material layer constitutes the battery cell body.

9. The battery cell according to claim 8, characterized in that: The two outermost pole sheets among the plurality of pole sheets stacked in layers are single-sided pole sheets, and the active material layer is not provided on the surface of the single-sided pole sheets facing the outer side of the battery cell body.

10. A battery device, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 9.

11. An electrical device, characterized in that: The electrical device comprises the battery device as claimed in claim 10, wherein the battery device is used to provide electrical energy; or the electrical device comprises the battery cell as claimed in any one of claims 1 to 9, wherein the battery cell is used to provide electrical energy.

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