CN117256074A - Connecting element, battery cell, battery and consumer - Google Patents

Abstract

The embodiment of the application discloses a connecting member, a battery monomer, a battery and electric equipment. The connection member is used for achieving electrical connection between electrode terminals and tabs of the battery cells, and comprises: the electrode terminal comprises an electrode terminal welding part, a connecting part and a main body part, wherein the connecting part is used for connecting the electrode terminal welding part and the main body part, the electrode terminal welding part is used for welding with an electrode terminal, the roughness of the surface, far away from the electrode terminal, of the electrode terminal welding part is larger than the roughness of the surface, far away from the electrode terminal, of the main body part, and the thickness of the electrode terminal welding part is smaller than the thickness of the main body part. According to the connecting component, the battery monomer, the battery and the electric equipment, the welding efficiency between the connecting component and the electrode terminal can be improved, and then the performance of the battery is improved.

Description

Connecting element, battery cell, battery and consumer Technical Field

The present application relates to the field of batteries, and more particularly, to a connection member, a battery cell, a battery, and an electric device.

Background

Energy conservation and emission reduction are key to sustainable development of the automobile industry. In this case, the electric vehicle is an important component for sustainable development of the automobile industry due to the advantage of energy conservation and environmental protection. For electric vehicles, battery technology is an important factor for development.

With the development of battery technology, how to improve the production and processing efficiency of batteries has become a particularly important problem in the development of battery technology.

Disclosure of Invention

The embodiment of the application provides a connecting element, battery monomer, battery and consumer, can improve the welding efficiency between connecting element and the electrode terminal, and then improve the performance of battery.

In a first aspect, there is provided a connection member for achieving electrical connection between electrode terminals of battery cells and tabs, the connection member comprising: the electrode terminal comprises an electrode terminal welding part, a connecting part and a main body part, wherein the connecting part is used for connecting the electrode terminal welding part and the main body part, the electrode terminal welding part is used for welding with an electrode terminal, the roughness of the surface, far away from the electrode terminal, of the electrode terminal welding part is larger than the roughness of the surface, far away from the electrode terminal, of the main body part, and the thickness of the electrode terminal welding part is smaller than the thickness of the main body part.

Therefore, in the connecting member according to the embodiment of the present application, the surface of the electrode terminal welding portion, which is remote from the electrode terminal, has a roughness greater than that of the surface of the main body portion, which is remote from the electrode terminal, which is advantageous in improving the welding effect. Especially for laser welding, the laser energy during welding can be absorbed through the rough surface of the electrode terminal welding part, so that the laser welding power is reduced, and the production cost is reduced; meanwhile, welding slag can be avoided, the welding effect is improved, the internal short circuit of the battery unit is prevented, and the safety performance and quality of the battery are improved. And, the thickness of this electrode terminal welding portion is less than the thickness of this main part, compares in the great condition of electrode terminal welding portion's thickness, and thickness is less can make this welding position melting penetrability better, under the circumstances that does not appear the rosin joint between the electrode assembly welding portion of this connecting element and electrode terminal, can suitably reduce welding power, also can guarantee the reliability between welding effect and this connecting element and the electrode terminal simultaneously, also can guarantee stability and reliability between the apron that connecting element and electrode terminal are located, and then improved battery cell's stability and security.

In some embodiments, a surface of the electrode terminal welding part facing the electrode terminal protrudes or is recessed from a surface of the body part facing the electrode terminal.

The surface of the electrode terminal welding part facing the electrode terminal protrudes from the surface of the main body part facing the electrode terminal, so that the electrode terminal welding part is closer to the electrode terminal, and the connection between the electrode terminal welding part and the electrode terminal welding part is convenient to realize; the surface of the electrode terminal welding part facing the electrode terminal is recessed from the surface of the main body part facing the electrode terminal, so that the space inside the battery cell can be fully utilized, and particularly, in the case that the surface of the electrode terminal facing the main body part protrudes from the surface of the cover plate facing the main body part, the occupied space of the connecting member can be reduced.

In some embodiments, the thickness H31 of the electrode terminal welding part and the thickness H33 of the body part satisfy: H33-H31 is more than or equal to 5 percent and H33 is more than or equal to 65 percent. If the thickness of the electrode terminal welding part is too small, it may cause the electrode terminal welding part to be melted through during welding; in contrast, if the thickness of the electrode terminal welding portion is excessively large, the welding power cannot be effectively reduced.

In some embodiments, the ratio of the area of the surface of the electrode terminal welding part facing the electrode terminal to the area of the surface of the connection member facing the electrode terminal ranges from [1/50,3/5]. If the area of the surface of the electrode terminal welding portion facing the electrode terminal is too small, that is, the thinned area of the electrode terminal welding portion is too small, welding is not facilitated, for example, if the actual welding area exceeds the thinned area, the thinned area cannot effectively reduce the welding power, and if the actual welding area is equal to the thinned area, the welding area is too small, and thus welding is unstable. Conversely, if the area of the electrode terminal welding portion facing the surface of the electrode terminal is too large, that is, the thinned area is too large, the welding power is not significantly increased due to the limited actual welding area, but the processing difficulty of the connecting member is increased, and the production efficiency is reduced.

In some embodiments, the thickness of the connecting portion is less than the thickness of the main body portion to facilitate processing while also reducing the overall weight of the connecting member, i.e., the weight of the battery cell.

In some embodiments, the thickness of the connection part is greater than that of the electrode terminal welding part, which is convenient for processing and implementation and can ensure the reliability of the connection part.

In some embodiments, the ratio of the thickness of the connecting portion to the thickness of the main body portion is greater than or equal to 4/5 to avoid structural instability of the connecting member when the thickness of the connecting portion is too small.

In some embodiments, the included angle between the connecting portion and the body portion is in the range of (90, 135 ° ], i.e., the angle of draw during machining, is typically greater than 90 ° to facilitate demolding, and conversely, is typically not set too great to increase machining difficulty.

In some embodiments, the body portion includes a tab weld area for welding with the tab to effect connection between the connection member and the tab.

In some embodiments, the tab welding region is located at an end of the body portion remote from the electrode terminal welding portion, so as to avoid interaction between the tab welding region and the electrode terminal welding portion, while also facilitating processing.

In some embodiments, the thickness of different regions of the body portion are equal to facilitate machining.

In some embodiments, the connection part surrounds the electrode terminal welding part, and the body part surrounds the connection part to secure the strength of the connection member, thereby securing the reliability of the battery cell.

In a second aspect, there is provided a battery cell comprising: an electrode terminal; an electrode assembly including a tab; the connection member of the first aspect or any one of the embodiments of the first aspect is used for realizing electrical connection between the electrode terminal and the tab.

In a third aspect, there is provided a battery comprising: a plurality of battery cells comprising a connecting member according to the first aspect or any one of the embodiments of the first aspect.

In a fourth aspect, there is provided a powered device comprising: and the battery is used for providing electric energy for the electric equipment and comprises the connecting component according to the first aspect or any embodiment of the first aspect.

In some embodiments, the powered device is a vehicle, a vessel, or a spacecraft.

Drawings

FIG. 1 is a schematic illustration of a vehicle according to one embodiment of the present application;

Fig. 2 is a schematic structural view of a battery according to an embodiment of the present application;

fig. 3 is an exploded view of a battery cell according to an embodiment of the present application;

FIG. 4 is a schematic structural view of a connecting member according to one embodiment of the present application;

FIG. 5 is a schematic top view of a connecting member according to one embodiment of the present application;

FIG. 6 is a schematic cross-sectional view of a connecting member according to one embodiment of the present application;

FIG. 7 is a schematic side view of a connecting member according to one embodiment of the present application;

fig. 8 is an exploded view of a battery cell according to another embodiment of the present application;

FIG. 9 is a schematic structural view of a connecting member according to another embodiment of the present application;

FIG. 10 is a schematic top view of a connecting member according to another embodiment of the present application;

FIG. 11 is a schematic side view of a connecting member according to another embodiment of the present application;

fig. 12 is an exploded view of a battery cell according to still another embodiment of the present application;

FIG. 13 is a schematic view of a structure of a connecting member according to yet another embodiment of the present application;

FIG. 14 is a schematic view of a structure of a connecting member according to yet another embodiment of the present application;

FIG. 15 is a schematic top view of a connecting member according to yet another embodiment of the present application;

fig. 16 is a schematic cross-sectional view of a connecting member according to yet another embodiment of the present application.

In the drawings, the drawings are not drawn to scale.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having" and any variations thereof in the description and claims of the present application and in the description of the figures above are intended to cover non-exclusive inclusions. The terms first, second and the like in the description and in the claims or in the above-described figures, are used for distinguishing between different objects and not necessarily for describing a particular sequential or chronological order.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "attached" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

The term "and/or" in this application is merely an association relation describing an associated object, and indicates that three relations may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone. In this application, the character "/" generally indicates that the associated object is an or relationship.

In the embodiments of the present application, the same reference numerals denote the same components, and in the interest of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, etc. dimensions of the various components in the embodiments of the present application, as well as the overall thickness, length, width, etc. dimensions of the integrated device, are illustrative only and should not be construed as limiting the present application in any way.

The term "plurality" as used herein refers to two or more (including two), and similarly, "plural sets" refers to two or more (including two), and "plural sheets" refers to two or more (including two).

In the present application, the battery cell may include a lithium ion secondary battery, a lithium ion primary battery, a lithium sulfur battery, a sodium lithium ion battery, a sodium ion battery, a magnesium ion battery, or the like, which is not limited by the embodiment of the present application. The battery cells may be cylindrical, flat, rectangular, or otherwise shaped, as well as the embodiments herein are not limited in this regard. The battery cells are generally classified into three types according to the packaging method: the cylindrical battery cell, the square battery cell and the soft pack battery cell are not limited thereto.

Reference to a battery in embodiments of the present application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in the present application may include a battery module or a battery pack, or the like. The battery generally includes a case for enclosing one or more battery cells. The case body can prevent liquid or other foreign matters from affecting the charge or discharge of the battery cells.

The battery cell comprises an electrode assembly and electrolyte, wherein the electrode assembly consists of a positive electrode plate, a negative electrode plate and a separation film. The battery cell mainly relies on metal ions to move between the positive pole piece and the negative pole piece to work. The positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer, wherein the positive electrode active material layer is coated on the surface of the positive electrode current collector, the positive electrode current collector without the positive electrode active material layer protrudes out of the positive electrode current collector coated with the positive electrode active material layer, and the positive electrode current collector without the positive electrode active material layer is used as a positive electrode lug. Taking a lithium ion battery as an example, the material of the positive electrode current collector may be aluminum, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate or the like. The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer, wherein the negative electrode active material layer is coated on the surface of the negative electrode current collector, the negative electrode current collector without the negative electrode active material layer protrudes out of the negative electrode current collector coated with the negative electrode active material layer, and the negative electrode current collector without the negative electrode active material layer is used as a negative electrode tab. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon, silicon, or the like. In order to ensure that the high current is passed without fusing, the number of positive electrode lugs is multiple and stacked together, and the number of negative electrode lugs is multiple and stacked together. The material of the separator may be polypropylene (PP) or Polyethylene (PE). In addition, the electrode assembly may be a wound structure or a lamination structure, and the embodiment of the present application is not limited thereto.

The development of battery technology is taking into consideration various design factors such as energy density, cycle life, discharge capacity, charge-discharge rate and other performance parameters, and the safety of the battery. For example, for a battery cell, it generally includes an electrode assembly, an electrolyte, a case accommodating the electrode assembly and the electrolyte, and a cap plate mounted on the case, on which electrode terminals for inputting or outputting electric power are generally mounted. When the battery cells are assembled, the electrode assembly and the electrode terminals on the cap plate are generally connected indirectly through connection members, i.e., the connection members are electrically connected to the electrode assembly and the electrode terminals, respectively, by welding. Generally, a laser welding mode is adopted between the electrode terminal and the connecting member, and the laser welding has the characteristics of high power, firm welding and stable structure. However, if the welding power is high, parts of materials such as plastic around the parts are easily melted; conversely, if the welding power is smaller, the cold welding phenomenon can occur, the welding effect is affected, the stability between the connecting component and the cover plate is further affected, and the performance of the battery monomer is further affected.

Accordingly, embodiments of the present application provide a connecting member comprising: electrode terminal welded part, connecting portion and main part. Wherein the connection portion is for connecting the electrode terminal welding portion and the main body portion, and the electrode terminal welding portion is for welding with the electrode terminal. The roughness of the surface of the electrode terminal welding part, which is far from the electrode terminal, is greater than that of the surface of the main body part, which is far from the electrode terminal, which is advantageous for improving the welding effect. Especially for laser welding, the laser energy during welding can be absorbed through the rough surface of the electrode terminal welding part, so that the laser welding power is reduced, and the production cost is reduced; meanwhile, welding slag can be avoided, the welding effect is improved, the internal short circuit of the battery unit is prevented, and the safety performance and quality of the battery are improved. In addition, the thickness of the electrode terminal welding part is smaller than that of the main body part. Thus, the thickness of the electrode terminal welding part is smaller so that the welding part is better in melt penetrability than in the case where the thickness of the electrode terminal welding part is larger, and the welding power can be appropriately reduced without the occurrence of cold joint between the electrode assembly welding part of the connection member and the electrode terminal, while ensuring the welding effect and the reliability between the connection member and the electrode terminal.

The technical scheme described in the embodiment of the application is applicable to various electric equipment using batteries. The electric equipment can be vehicles, mobile phones, portable equipment, notebook computers, ships, spacecrafts, electric toys, electric tools and the like. The vehicle can be a fuel oil vehicle, a fuel gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended vehicle; spacecraft including airplanes, rockets, space shuttles, spacecraft, and the like; the electric toy includes fixed or mobile electric toys such as a game machine, an electric car toy, an electric ship toy, and an electric airplane toy; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railroad power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete shakers, and electric planers. The embodiment of the application does not limit the electric equipment in particular.

For convenience of explanation, the following embodiments take electric equipment as an example of a vehicle.

For example, as shown in fig. 1, a schematic structural diagram of a vehicle 1 according to an embodiment of the present application, the vehicle 1 may be a fuel-oil vehicle, a gas-fired 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. The motor 40, the controller 50, and the battery 10 may be provided inside the vehicle 1, and the controller 50 is configured to control the battery 10 to supply power to the motor 40. For example, the battery 10 may be provided at the bottom or the head or the tail of the vehicle 1. The battery 10 may be used for power supply of the vehicle 1, e.g. the battery 10 may be used as an operating power source for the vehicle 1, for electrical circuitry of the vehicle 1, e.g. for start-up, navigation and operational power requirements of the vehicle 1. In another embodiment of the present application, the battery 10 may not only serve as an operating power source for the vehicle 1, but also as a driving power source for the vehicle 1, instead of or in part instead of fuel oil or natural gas, to provide driving power for the vehicle 1.

To meet different power requirements, the battery may include a plurality of battery cells, where the plurality of battery cells may be connected in series or parallel or a series-parallel connection, and the series-parallel connection refers to a mixture of series and parallel connection. The battery may also be referred to as a battery pack. In some embodiments, a plurality of battery cells may be connected in series or parallel or series-parallel to form a battery module, and then connected in series or parallel or series-parallel to form a battery. That is, a plurality of battery cells may be directly assembled into a battery, or may be assembled into a battery module first, and the battery module may be assembled into a battery.

For example, fig. 2 illustrates a schematic structure of a battery 10 according to one embodiment of the present application, and the battery 10 may include at least one battery module 200. The battery module 200 includes a plurality of battery cells 20. The battery 10 may further include a case 11, in which the case 11 has a hollow structure, and the plurality of battery cells 20 are accommodated in the case 11. Fig. 2 illustrates one possible implementation of the case 11 according to the embodiment of the present application, and as shown in fig. 2, the case 11 may include two parts, which are referred to herein as a first case portion 111 and a second case portion 112, respectively, and the first case portion 111 and the second case portion 112 are fastened together. The shape of the first and second case parts 111 and 112 may be determined according to the combined shape of the battery modules 200, at least one of the first and second case parts 111 and 112 having one opening. For example, as shown in fig. 2, each of the first case portion 111 and the second case portion 112 may be a hollow rectangular parallelepiped and only one surface thereof is an open surface, the opening of the first case portion 111 and the opening of the second case portion 112 are disposed opposite to each other, and the first case portion 111 and the second case portion 112 are engaged with each other to form the case 11 having a closed chamber.

As another example, unlike the one shown in fig. 2, only one of the first and second case parts 111 and 112 may be a hollow rectangular parallelepiped having an opening, and the other may be a plate-like shape to cover the opening. For example, here, the second case portion 112 is a hollow rectangular parallelepiped and only one face is an opening face, and the first case portion 111 is a plate-like shape, and then the first case portion 111 is covered at the opening of the second case portion 112 to form a case 11 having a closed chamber that can be used to house a plurality of battery cells 20. The plurality of battery cells 20 are connected in parallel or in series-parallel, and then are placed in the box 11 formed by buckling the first box 111 and the second box 112.

In some embodiments, the battery 10 may further include other structures, which are not described in detail herein. For example, the battery 10 may further include a bus member for making electrical connection between the plurality of battery cells 20, such as parallel or series-parallel connection. Specifically, the bus member may realize electrical connection between the battery cells 20 by connecting electrode terminals of the battery cells 20. Further, the bus member may be fixed to the electrode terminals of the battery cells 20 by welding. The electric power of the plurality of battery cells 20 may be further led out through the case 11 by the conductive mechanism.

The number of battery cells 20 in the battery module 200 may be set to any value according to different power requirements. The plurality of battery cells 20 may be connected in series, parallel, or series-parallel to achieve a larger capacity or power. Since the number of battery cells 20 included in each battery 10 may be large, the battery cells 20 are arranged in groups for easy installation, and each group of battery cells 20 constitutes the battery module 200. The number of battery cells 20 included in the battery module 200 is not limited, and may be set according to requirements. The battery may include a plurality of battery modules 200, and the battery modules 200 may be connected in series, parallel, or series-parallel.

Fig. 3 is a schematic structural view of a battery cell 20 according to an embodiment of the present application, and as shown in fig. 3, the battery cell 20 according to an embodiment of the present application may include one or more electrode assemblies 22 and a case 21 for accommodating the electrode assemblies 22.

It should be appreciated that the housing 21 of the embodiments of the present application may be a polyhedral structure, as shown in fig. 3. Specifically, the case 21 may include a housing 211 and a cover plate 212, wherein the housing 211 may be a hollow structure having at least one end formed with an opening, and the cover plate 212 may be shaped to fit the shape of the housing 211, and the cover plate 212 is used to cover the opening of the housing 211 so that the case 21 insulates the internal environment of the battery cell 20 from the external environment. If the housing 211 has a hollow structure with an opening formed at one end, the cover 212 may be provided as one; if the housing 211 has a hollow structure with openings formed at opposite ends, two cover plates 212 may be provided, and the two cover plates 212 cover the openings at the opposite ends of the housing 211.

The material of the housing 211 according to the embodiment of the present application may be various, such as copper, iron, aluminum, steel, aluminum alloy, etc. The material of the cover 212 may be various, such as copper, iron, aluminum, steel, aluminum alloy, etc., and the material of the cover 212 may be the same as or different from the material of the housing 211.

The housing 21 of the embodiment of the present application may be of various shapes, such as a cylinder, a rectangular parallelepiped, or the like. The housing 211 and the cover plate 212 are matched in shape, for example, as shown in fig. 3, the housing 211 may be a rectangular parallelepiped structure, and the cover plate 212 is a rectangular plate structure matched with the housing 211.

For convenience of explanation, the case 21 is exemplified as a rectangular parallelepiped in this application. Specifically, as shown in fig. 3, the housing 21 includes: a housing 211, wherein the housing 211 has a hollow structure with one end opened; a cover plate 212, the cover plate 212 for covering the opening of the case 211 to form a closed cavity in which the electrode assembly 22 is placed.

Alternatively, the housing 21 of the embodiment of the present application may be provided with a plurality of components. For example, as shown in fig. 3, the battery cell 20 may further include a pressure relief mechanism 213, where the pressure relief mechanism 213 may be disposed on any wall of the housing 21, for example, fig. 3 illustrates the pressure relief mechanism 213 located on the cover 212. Specifically, the pressure relief mechanism 213 is used to actuate to relieve the internal pressure or temperature of the battery cell 20 when the internal pressure or temperature reaches a threshold.

For the battery 10, the main safety hazard comes from the charging and discharging process, and in order to improve the safety performance of the battery 10, a pressure release mechanism 213 is generally provided for the battery cell 20. The pressure release mechanism 213 refers to an element or component that actuates to release the internal pressure or temperature of the battery cell 20 when the internal pressure or temperature reaches a predetermined threshold. The predetermined threshold may be adjusted according to design requirements. The predetermined threshold may depend on the material of one or more of the positive electrode tab, the negative electrode tab, the electrolyte, and the separator in the battery cell 20. The pressure relief mechanism 213 may be implemented by a score on the cover plate 212, or an element or component such as pressure sensitive or temperature sensitive may be employed, i.e., when the internal pressure or temperature of the battery cell 20 reaches a predetermined threshold, the pressure relief mechanism 213 is actuated, thereby forming a channel through which the internal pressure or temperature may be vented.

By "actuation" as referred to herein is meant that the pressure relief mechanism 213 is actuated such that the internal pressure and temperature of the battery cell 20 is relieved. The actions taken by pressure relief mechanism 213 may include, but are not limited to: at least a portion of the pressure relief mechanism 213 breaks, tears, melts, etc. Upon actuation of the pressure relief mechanism 213, the high temperature and high pressure material inside the battery cell 20 may be discharged as a discharge from the pressure relief mechanism 213. In this way, the cell 20 can be depressurized under controlled pressure or temperature, thereby avoiding a potentially more serious accident.

References herein to emissions from the battery cell 20 include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of a separator, high-temperature and high-pressure gas generated by reaction, flame, and the like.

The pressure release mechanism 213 on the battery cell 20 has an important effect on the safety of the battery. For example, when the battery cell 20 is short-circuited, overcharged, etc., thermal runaway may occur inside the battery cell 20 and thus the pressure or temperature may rise suddenly. In this case, the pressure release mechanism 213 is actuated to release the internal pressure and temperature to prevent explosion and ignition of the battery cell 20.

As shown in fig. 3, a liquid filling hole 215 may be provided in any one of the walls of the case 21 of the battery cell 20, and for example, in fig. 3, the liquid filling hole 215 is located on the cover 212. The electrolyte injection hole 215 is used to inject the electrolyte into the casing 21 through the electrolyte injection hole 215.

Optionally, as shown in fig. 3, the outer surface of the housing 21 may be further provided with a blue film 2111, for example, may be provided on the outer surface of the housing 211 to achieve the functions of insulation and protection of the battery cell 20, but the embodiment of the present application is not limited thereto.

In the battery cell 20, the inside of the case 211 is used to accommodate the electrode assembly 22, and the electrode assembly 22 in the case 211 may be provided in one or more pieces according to actual use requirements. For example, fig. 3 exemplifies that the battery cell 20 includes two electrode assemblies 22 aligned in the first direction X, but the embodiment of the present application is not limited thereto. Wherein the first direction X, the second direction Y and the third direction Z are perpendicular to each other.

The electrode assembly 22 of the embodiment of the present application is a component in which electrochemical reactions occur in the battery cell 20. The electrode assembly 22 may have a cylindrical shape, a rectangular parallelepiped shape, or the like, and if the electrode assembly 22 has a cylindrical structure, the case 211 may have a cylindrical structure, and if the electrode assembly 22 has a rectangular parallelepiped structure, the case 211 may have a rectangular parallelepiped structure.

For any one of the electrode assemblies 22, the electrode assembly 22 may include a tab 222 and a body portion 221. Specifically, as shown in fig. 3, the electrode assembly 22 may include at least two tabs 222, and the two tabs 222 may include a positive electrode tab 222a and a negative electrode tab 222b, and the positive electrode tab 222a may be formed by laminating a portion of the positive electrode sheet on which the positive electrode active material layer is not coated, and the negative electrode tab 222b may be formed by laminating a portion of the negative electrode sheet on which the negative electrode active material layer is not coated. The main body portion 221 of the electrode assembly 22 may be formed by laminating or winding a portion coated with a positive electrode active material layer on a positive electrode tab and a portion coated with a negative electrode active material layer on a negative electrode tab.

The casing 21 of the embodiment of the present application is further provided with an electrode terminal 214, and the electrode terminal 214 is electrically connected to the electrode assembly 22 to output the electric energy of the battery cell 20. For example, as shown in fig. 3, the battery cell 20 may further include at least two electrode terminals 214, and the two electrode terminals 214 may be disposed on the cap plate 212. The cap plate 212 is generally in the shape of a flat plate, and two electrode terminals 214 are fixed to the flat plate surface of the cap plate 212, the two electrode terminals 214 being a positive electrode terminal 214a and a negative electrode terminal 214b, respectively. Each electrode terminal 214 is provided with a connection member 30, and the connection member 30 is positioned between the cap plate 212 and the electrode assembly 22 for electrically connecting the electrode assembly 22 and the electrode terminal 214. Specifically, as shown in fig. 3, the positive electrode tab 222a of the electrode assembly 22 may be connected to the positive electrode terminal 214a through one connection member 30, and the negative electrode tab 222b of the electrode assembly 22 may be connected to the negative electrode terminal 214b through the other connection member 30.

The connection member 30 of the embodiment of the present application will be described in detail with reference to the accompanying drawings. Fig. 4 shows a schematic perspective view of a connection member 30 according to an embodiment of the present application, for example, the connection member 30 shown in fig. 4 may be any connection member 30 in the battery cell 20, where the connection member 30 shown in fig. 4 is exemplified by the right connection member 30 shown in fig. 3; fig. 5 shows a schematic top view of a connecting member 30 of an embodiment of the present application, i.e., fig. 5 shows the surface of connecting member 30 facing electrode assembly 22; FIG. 6 shows a schematic cross-sectional view of the connecting member 30 of an embodiment of the present application, the schematic cross-sectional view being in the direction A-A' shown in FIG. 5; fig. 7 shows a schematic side view of the connecting member 30 of an embodiment of the present application, for example, fig. 7 may be a side view of the left side of the connecting member 30 shown in fig. 5.

As shown in fig. 4 to 7, the connection member 30 of the embodiment of the present application is for making electrical connection between the electrode terminals 214 of the battery cells 20 and the tabs 222, and the connection member 30 includes: an electrode terminal welding part 31, a connecting part 32, and a main body part 33. Wherein the connection part 32 is for connecting the electrode terminal welding part 31 and the main body part 33, the electrode terminal welding part 31 being for welding with the electrode terminal 214; the roughness of the surface of the electrode terminal welding part 31 away from the electrode terminal 214 is greater than the roughness of the surface of the body part 33 away from the electrode terminal 214, and the thickness H31 of the electrode terminal welding part 31 is smaller than the thickness H33 of the body part 33.

It should be understood that the electrode terminal welding part 31 and the electrode terminal 214 of the embodiment of the present application may be connected by welding. Specifically, the welding may be laser welding to ensure stability and reliability between the connection member 30 and the cap plate 212 where the electrode terminal 214 is located.

Therefore, in the connecting member 30 of the embodiment of the present application, the surface of the electrode terminal welding part 31 remote from the electrode terminal 214 has a roughness greater than that of the surface of the main body part 33 remote from the electrode terminal 214, which is advantageous in improving the welding effect. Particularly for laser welding, the laser energy during welding can be absorbed through the rough surface of the electrode terminal welding part 31, so that the laser welding power is reduced, and the production cost is reduced; meanwhile, welding slag can be avoided, the welding effect is improved, the internal short circuit of the battery cell 20 is prevented, and the safety performance and quality of the battery 10 are improved.

Moreover, the thickness H31 of the electrode terminal welding portion 31 in the embodiment of the application is smaller than the thickness H33 of the main body portion 33, and compared with the case that the thickness H31 of the electrode terminal welding portion 31 is larger, the smaller thickness can enable the welding portion 31 to have better melting penetrability, and under the condition that no cold welding occurs between the electrode assembly welding portion 31 of the connecting member 30 and the electrode terminal 214, the welding power can be properly reduced, meanwhile, the welding effect and the reliability between the connecting member 30 and the electrode terminal 214 can be ensured, and the stability and the reliability between the connecting member 30 and the cover plate 212 where the electrode terminal 214 is located can be ensured, so that the stability and the safety of the battery cell 20 are improved.

It should be understood that the roughness of different regions of the surface of the electrode terminal welding part 31 remote from the electrode terminal 214 may be the same or different. If the roughness of the different regions of the surface of the electrode terminal welding part 31 away from the electrode terminal 214 is different, the roughness of the surface of the electrode terminal welding part 31 away from the electrode terminal 214 of the embodiment of the present application may represent the maximum value or the average value or the minimum value of the roughness of the different regions on the surface. Similarly, the surface of the main body portion 33 remote from the electrode terminal 214 may have the same roughness or may have different roughness. If the roughness of the surface of the main body 33 away from the electrode terminal 214 is different, the roughness of the surface of the main body 33 away from the electrode terminal 214 in the embodiment of the present application may be calculated in a manner consistent with the roughness of the surface of the electrode terminal welding portion 31 away from the electrode terminal 214, and may represent the maximum value, the average value, or the minimum value of the roughness of the different regions on the surface, so that at least a partial region of the surface of the electrode terminal welding portion 31 away from the electrode terminal 214 is rougher than the surface of the main body 33 away from the electrode terminal 214. For example, the average value of the roughness of the surface of the electrode terminal welding part 31 away from the electrode terminal 214 is greater than the average value of the roughness of the surface of the main body part 33 away from the electrode terminal 214, but the embodiment of the present application is not limited thereto.

It is understood that the roughness of at least a partial region of the surface of the electrode terminal welding part 31 remote from the electrode terminal 214 may be increased in various ways. For example, a roughened surface may be formed in at least a partial region of the surface of the electrode terminal welding part 31 remote from the electrode terminal 214 by means of a sanding process, a sand blasting process, or a solvent etching process, for example, rectangular particles of the surface of the electrode terminal welding part 31 may be illustrated in fig. 4 to 5, but the embodiment of the present application is not limited thereto.

It should be understood that the thickness H31 of the electrode terminal welding part 31 of the embodiment of the present application may be the thickness of the electrode terminal welding part 31 in the third direction Z perpendicular to the surface of the electrode terminal welding part 31 facing the electrode terminal 214 or perpendicular to the surface of the electrode terminal welding part 31 facing away from the electrode terminal 214. Similarly, the thickness H33 of the main body 33 in the embodiment of the present application may be the thickness of the main body 33 along the third direction Z.

The electrode terminal welding parts 31 of the present embodiment may be provided to have the same thickness in different regions or may be provided to have different thicknesses. Specifically, the thicknesses of different regions of the electrode terminal welding part 31 are generally set to be equal to facilitate processing. If the thicknesses of the different regions of the electrode terminal welding part 31 are not equal, for example, only a part of the electrode terminal welding part 31 is thinned, the thickness H31 of the electrode terminal welding part 31 in the embodiment of the present application may represent a maximum value, an average value or a minimum value of the thickness of the electrode terminal welding part 31, and the embodiment of the present application is not limited thereto.

Similarly, the thicknesses of different regions of the main body portion 33 of the embodiment of the present application may also be set equal or unequal. Specifically, the thicknesses of different regions of the main body portion 33 are generally set equal to facilitate processing. If the thicknesses of the different regions of the main body 33 are not equal, the thickness H33 of the main body 33 in the embodiment of the present application should be calculated in a manner consistent with the electrode terminal welding portion 31, and the thickness H33 of the main body 33 may represent a maximum value, an average value, or a minimum value of the thickness of the main body 33. For example, if the thicknesses of the different regions of the electrode terminal welding portion 31 are different and the thicknesses of the different regions of the main body portion 33 are also different, the thickness H31 of the electrode terminal welding portion 31 may be the maximum value of the thickness of the electrode terminal welding portion 31, and correspondingly, the thickness H33 of the main body portion 33 may be the maximum value of the thickness of the main body portion 33, but the embodiment of the present application is not limited thereto.

In the embodiment of the present application, the thickness H31 of the electrode terminal welding part 31 is smaller than the thickness H33 of the main body part 33, and the thickness difference therebetween may be set according to practical applications. For example, the thickness H31 of the electrode terminal welding portion 31 and the thickness H33 of the main body portion 33 may be set to satisfy: H33-H31 is more than or equal to 5 percent and H33 is more than or equal to 65 percent. For another example, the value range of the ratio of the thickness H31 of the electrode terminal welding part 31 to the thickness H33 of the main body part 33 may be set to [1/3,11/12]. If the thickness H31 of the electrode terminal welding part 31 is too small, it may cause the electrode terminal welding part 31 to melt through during welding; in contrast, if the thickness H31 of the electrode terminal welding portion 31 is too large, the welding power cannot be effectively reduced. For example, the ratio of the thickness H31 of the electrode terminal welding part 31 to the thickness H33 of the main body part 33 may be set to be greater than or equal to 1/2; for another example, the ratio of the thickness H31 of the electrode terminal welding part 31 to the thickness H33 of the main body part 33 may be set to be greater than or equal to 2/3.

For example, the thickness H33 of the main body portion 33 is 1mm, and the thickness H31 of the electrode terminal welding portion 31 is 0.9mm; alternatively, the thickness H33 of the main body 33 is 1.2mm, and the thickness H31 of the electrode terminal welding portion 31 is 1mm; alternatively, the thickness H33 of the main body 33 is 1.5mm, and the thickness H31 of the electrode terminal welding portion 31 is 1.2mm or 1mm.

In the embodiment of the present application, the area of the electrode terminal welding part 31 may also be set according to practical applications. . Specifically, the ratio of the area of the electrode terminal-facing surface of the electrode terminal welding part 31 to the area of the electrode terminal-facing surface of the connecting member 30 is in the range of [1/50,3/5]. Alternatively, considering that the electrode terminal welding part 31 of the embodiment of the present application may be partially thinned, it is possible to set the range of values of the ratio of the area of the surface facing the electrode terminal of the thinned region of the electrode terminal welding part 31 to the area of the surface facing the electrode terminal of the connection member 30 to [1/50,3/5]. If the area of the surface of the electrode terminal welding part 31 facing the electrode terminal 214 is too small, that is, if the thinned area of the electrode terminal welding part 31 is too small, welding is not facilitated, for example, if the actual welding area exceeds the thinned area, the thinned area cannot effectively reduce the welding power, and if the actual welding area is equal to the thinned area, the welding area is too small, and thus welding is unstable. In contrast, if the area of the surface of the electrode terminal welding part 31 facing the electrode terminal 214 is excessively large, that is, the thinned area is excessively large, the excessively large thinned area does not significantly increase the welding power due to the limited actual welding area, but rather increases the processing difficulty of the connecting member 30, and reduces the production efficiency.

Alternatively, the connecting portion 32 of the embodiment of the present application is located between the electrode terminal welding portion 31 and the main body portion 33, and the connecting portion 32 may also be subjected to a thinning process. Specifically, as shown in fig. 4 to 7, the thickness H32 of the connection part 32 is smaller than the thickness H33 of the body part 33, so that the processing is facilitated, and at the same time, the entire weight of the connection member 30, that is, the weight of the battery cell 20, can be reduced.

In the embodiment of the present application, the thickness H32 of the connection portion 32 may be set according to practical applications. For example, the thickness H32 of the connection portion 32 is greater than the thickness H31 of the electrode terminal welding portion 31, which is convenient for processing and can ensure the reliability of the connection portion 32.

For another example, the ratio of the thickness H32 of the connecting portion 32 to the thickness H33 of the main body portion 33 is greater than or equal to 4/5 to avoid the unstable structure of the connecting member 30 when the thickness H32 of the connecting portion 32 is too small.

It should be understood that the thinning of the electrode terminal welding part 31 and/or the connecting part 32 of the embodiment of the present application may be achieved in various ways, and the thinning of the electrode terminal welding part 31 and the connecting part 32 may be achieved in the same or different ways. For example, it is possible to simultaneously achieve thinning of the electrode terminal welding part 31 and the connecting part 32 in the same manner to improve the processing efficiency. For example, the electrode terminal welding part 31 and the connection part 32 may be thinned by press-drawing, or may be processed by turning, milling, or the like, but the embodiment is not limited thereto.

It is to be understood that the surface of the electrode terminal welding part 31 facing the electrode terminal 214 of the embodiment of the present application protrudes or is recessed or flush with the surface of the main body part 33 facing the electrode terminal 214. Alternatively, as an example, as shown in fig. 4 to 7, the surface of the electrode terminal welding part 31 facing the electrode terminal 214 protrudes from the surface of the main body part 33 facing the electrode terminal 214, so that the electrode terminal welding part 31 is closer to the electrode terminal 214, facilitating the connection therebetween.

Alternatively, the connecting portion 32 in the embodiment of the present application is used to connect the main body portion 33 and the electrode terminal welding portion 31, and the angle θ between the connecting portion 32 and the main body portion 33 in the embodiment of the present application may be set according to actual processing requirements. Specifically, as shown in fig. 4 to 7, considering that a rounded corner is generally provided between the connection portion 32 and the main body portion 33, a rounded corner is also generally provided between the connection portion 32 and the electrode terminal welding portion 31, so as to facilitate processing. Therefore, the angle θ between the connecting portion 32 and the main body portion 33 in the embodiment of the present application refers to the angle between the region of the connecting portion 32 from which the rounded corners are removed and the region of the main body portion 33 from which the rounded corners are removed.

Alternatively, the included angle θ between the connecting portion 32 and the main body portion 33 may be in a range of (90 °,135 ° ], specifically, the included angle θ between the connecting portion 32 and the main body portion 33 is a draft angle θ during processing, which is generally greater than 90 ° to facilitate demolding, and conversely, the draft angle θ is not generally set too large to increase the processing difficulty.

It should be understood that, as shown in fig. 4 to 7, the body portion 33 includes a tab welding area 331, and the tab welding area 331 is used to weld with the tab 222 to achieve the connection between the connection member 30 and the tab 222. Specifically, the tab welding area 331 may be at least a partial area of the main body portion 33; also, the body portion 33 may include one tab welding area 331 that is communicated with each other, or may include a plurality of tab welding areas 331 that are not communicated with each other. For example, fig. 5 shows a possible location of the tab welding area 331, but the embodiment of the present application is not limited thereto.

Alternatively, as shown in fig. 4 to 7, the relative positions of the tab welding region 331 and the electrode terminal welding part 31 of the embodiment of the present application may be set according to practical applications. For example, the tab welding region 331 is located at an end of the body portion 33 remote from the electrode terminal welding portion 31 to avoid interaction between the tab welding region 331 and the electrode terminal welding portion 31, while also facilitating processing.

Alternatively, the tab welding area 331 and the tab 222 in the embodiment of the present application may be electrically connected by welding, for example, an ultrasonic welding manner may be adopted.

Optionally, as shown in fig. 4 to 7, the main body portion 33 of the connection member 30 may further have a notch 332. For example, a notch 332 may be provided in a region of the main body 333 away from the electrode terminal welding part 31 to remove the surplus material of the main body 33, thereby reducing the weight of the connection member 30, which may allow the battery cell 20 to be reduced in weight, as well as the battery 10.

Alternatively, as shown in fig. 4 to 7, the notch 332 of the main body 33 may have a U-shape for easy processing. In addition, the connection member 30 may be further provided with a chamfer structure 333, and the chamfer structure 333 may be used for foolproof to facilitate mounting of the connection member 30. Alternatively, the chamfer structure 333 may be provided at any one corner of the connection member 30, for example, the chamfer structure 333 may be provided at an edge corner of the U-shaped notch 332, or the chamfer structure 333 may be provided at other corner positions, and the embodiment is not limited thereto.

It should be understood that the shape and position of the electrode terminal welding part 31 of the embodiment of the present application may be set according to practical applications. For example, the electrode terminal welding part 31 may have a circular, rectangular or triangular shape to facilitate processing. As another example, as shown in fig. 4 to 7, the connecting part 32 surrounds the electrode terminal welding part 31, the body part 33 surrounds the connecting part 32, and since the thickness H33 of the body part 33 is greater than the thickness H31 of the electrode terminal welding part 31, the surrounding arrangement can secure the strength of the connecting member 30, thereby securing the reliability of the battery cell 20.

Alternatively, the electrode terminal welding part 31 of the embodiment of the present application may have other arrangement, unlike the connection member 40 shown in fig. 4 to 7. For example, fig. 8 shows an exploded structure schematic view of a battery cell 20 according to another embodiment of the present application; fig. 9 shows a schematic structural view of a connection member 30 according to another embodiment of the present application, for example, the connection member 30 shown in fig. 9 may be any connection member 30 in the battery cell 20, where the connection member 30 shown in fig. 9 is exemplified by the right connection member 30 shown in fig. 8; fig. 10 shows a schematic top view of a connecting member 30 according to another embodiment of the present application, i.e., fig. 10 shows a surface of the connecting member 30 facing the electrode assembly 22; fig. 11 shows a schematic side view of a connecting member 30 according to another embodiment of the present application, for example, fig. 11 may be a side view of a lower edge of the connecting member 30 shown in fig. 10.

It should be understood that fig. 8 and fig. 4 of the embodiment of the present application only differ in that the connecting member 30 is different, and other components shown in fig. 8 are applicable to the related description of fig. 4, and are not repeated herein for brevity.

In addition, the connection member 30 shown in fig. 8 to 11 is different from the connection member 30 shown in fig. 3 to 7 only in the shape and position of the electrode terminal welding part 31, and the rest of the description is applicable to the related description of the connection member 30 shown in fig. 3 to 7, which is not repeated herein for brevity. For example, similar to the connection member 30 shown in fig. 3 to 7, the surface of the electrode terminal welding part 31 of the connection member 30 shown in fig. 8 to 11 facing the electrode terminal 214 also protrudes from the surface of the main body part 33 facing the electrode terminal 214.

However, unlike the connection member 30 shown in fig. 3 to 7, the electrode terminal welding parts 31 and the body parts 33 of the connection member 30 shown in fig. 8 to 11 are respectively located at opposite ends of the connection part 32, so that the processing is easier and the interaction between the electrode terminal welding parts 31 and the body parts 33 can be avoided.

It should be understood that, in the case where the surface of the electrode terminal welding part 31 facing the electrode terminal 214 protrudes from the surface of the main body part 33 facing the electrode terminal 214, as shown in fig. 3 to 11, the surface of the electrode terminal welding part 31 facing away from the electrode terminal 214 may protrude from the surface of the main body part 33 facing the electrode terminal 214; alternatively, unlike this, the surface of the electrode terminal welding part 31 away from the electrode terminal 214 may be flush with the surface of the body part 33 away from the electrode terminal 214, and the embodiment is not limited thereto.

Alternatively, as another embodiment, the surface of the electrode terminal welding part 31 facing the electrode terminal 214 of the embodiment of the present application may be recessed from the surface of the main body part 33 facing the electrode terminal 214. Specifically, fig. 12 shows an exploded structural schematic view of a battery cell 20 according to still another embodiment of the present application; fig. 13 shows a schematic structural view of a connection member 30 according to still another embodiment of the present application, for example, the connection member 30 shown in fig. 13 may be any connection member 30 in the battery cell 20, and the connection member 30 shown in fig. 13 is exemplified as the right connection member 30 shown in fig. 12.

It should be understood that fig. 12 differs from fig. 4 or fig. 8 in the embodiment of the present application only in that the connecting member 30 is different, and other components shown in fig. 12 are applicable to the related description of fig. 4 or fig. 8, and are not repeated herein for brevity.

In addition, the connection member 30 shown in fig. 12 to 13 is different from the connection member 30 shown in fig. 8 to 11 only in that: the surface of the electrode terminal welding part 31 of the connection member 30 facing the electrode terminal 214 in fig. 8 to 11 protrudes from the surface of the body part 33 facing the electrode terminal 214, and the surface of the electrode terminal welding part 31 of the connection member 30 facing the electrode terminal 214 shown in fig. 12 and 13 is recessed from the surface of the body part 33 facing the electrode terminal 214, that is, the relative positions of the electrode terminal welding part 31 and the body part 33 are different. The surface of the electrode terminal welding part 31 of the connection member 30 facing the electrode terminal 214 is recessed from the surface of the body part 33 facing the electrode terminal 214, so that the space between the body part 221 of the electrode assembly 22 and the surface of the electrode terminal 214 facing the body part 221 can be more fully utilized, and particularly in the case that the surface of the electrode terminal 214 facing the body part 221 protrudes from the surface of the cap plate 212 facing the body part 221, the surface of the electrode terminal welding part 31 facing the electrode terminal 214 is recessed from the surface of the body part 33 facing the electrode terminal 214, so that the space utilization inside the battery cell 20 can be improved.

The rest of the descriptions of the connection member 30 shown in fig. 12 to 13 are applicable to the related descriptions of the connection member 30 shown in fig. 8 to 11, for example, the thickness setting, the roughness setting, the angle setting, etc. of the respective areas of the connection member 30 in fig. 12 to 13 are the same as those of the connection member 30 shown in fig. 8 to 11, and are not repeated herein for brevity.

Alternatively, in the case where the surface of the electrode terminal welding part 31 of the connection member 30 facing the electrode terminal 214 is recessed from the surface of the main body part 33 facing the electrode terminal 214, as shown in fig. 12 and 13, the surface of the electrode terminal welding part 31 facing away from the electrode terminal 214 may also be recessed from the surface of the main body part 33 facing away from the electrode terminal 214; alternatively, the surface of the electrode terminal welding part 31 remote from the electrode terminal 214 may be flush with the surface of the main body part 33 remote from the electrode terminal 214.

Fig. 14 shows a schematic structural view of a connecting member 30 according to still another embodiment of the present application; fig. 15 shows a schematic top view of a connecting member 30 according to a further embodiment of the present application; fig. 16 shows a schematic cross-sectional view of a connecting member 30 according to yet another embodiment of the present application, for example, fig. 16 may be a schematic cross-sectional view along the direction B-B' shown in fig. 15. If the thickness reduction of the electrode terminal welding part 31 of the connection member 30 is not considered, the electrode terminal welding part 31, the connection part 32, and the body part 33 may be disposed to be flush, i.e., the connection member 30 may have a uniform flat plate-like structure. In this way, when the thickness of the electrode terminal welding part 31 of the connection member 30 is smaller than the body part 33, it may be achieved by thinning the side of the electrode terminal welding part 31 away from the electrode terminal 214 and/or thinning the side of the electrode terminal welding part 31 toward the electrode terminal 214.

For example, as shown in fig. 14 to 16, the side of the electrode terminal welding part 31 near the electrode terminal 214 may be subjected to thinning processing such that the thickness H31 of the electrode terminal welding part 31 is smaller than the thickness H33 of the main body part 33, and the thinning process does not affect the roughened surface of the electrode terminal welding part 31 away from the electrode terminal 214. As shown in fig. 16, the thickness of the connection portion 32 may be gradually increased from the side near the electrode terminal welding portion 31 to the side near the main body portion 33, so that the electrode terminal welding portion 31 is uniformly transited to the main body portion 33, thereby facilitating the process.

Alternatively, the area of the electrode terminal welding part 31 of the embodiment of the present application may be greater than or equal to the area of the actual welding area between the electrode terminal 214 and the connection member 30. For example, as shown in fig. 14 to 16, the region of the electrode terminal welding part 31 on the surface of the connection member 30 remote from the electrode terminal 214 may be divided according to roughness, but the actual welding region between the electrode terminal 214 and the connection member 30 may be a part of the electrode terminal welding part 31.

While the present application has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the present application. In particular, the technical features mentioned in the respective 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 encompasses all technical solutions falling within the scope of the claims.

Claims (15)

1. A connection member for achieving electrical connection between electrode terminals of battery cells and tabs, the connection member comprising: electrode terminal welding parts, connecting parts and main body parts,

   the connecting portion is used for connecting the electrode terminal welding portion and the main body portion, the electrode terminal welding portion is used for being welded with the electrode terminal, the roughness of the surface, far away from the electrode terminal, of the electrode terminal welding portion is larger than the roughness of the surface, far away from the electrode terminal, of the main body portion, and the thickness of the electrode terminal welding portion is smaller than the thickness of the main body portion.
2. The connecting member according to claim 1, wherein a surface of the electrode terminal welding portion facing the electrode terminal protrudes or is recessed from a surface of the main body portion facing the electrode terminal.
3. The connecting member according to claim 1 or 2, wherein a thickness H31 of the electrode terminal welding portion and a thickness H33 of the main body portion satisfy: H33-H31 is more than or equal to 5 percent and H33 is more than or equal to 65 percent.
4. A connecting member according to any one of claims 1 to 3, wherein the ratio of the area of the surface of the electrode terminal welding portion facing the electrode terminal to the area of the surface of the connecting member facing the electrode terminal has a value in the range of [1/50,3/5].
5. The connecting member according to any one of claims 1 to 4, wherein a thickness of the connecting portion is smaller than a thickness of the main body portion.
6. The connection member according to claim 5, wherein a thickness of the connection portion is greater than a thickness of the electrode terminal welding portion.
7. A connecting member according to claim 5 or 6, wherein the ratio of the thickness of the connecting portion to the thickness of the main body portion is greater than or equal to 4/5.
8. The connecting member according to any one of claims 1 to 7, wherein the included angle between the connecting portion and the main body portion has a value ranging from (90 °,135 °).
9. The connection member according to any one of claims 1 to 8, wherein the main body portion includes a tab welding region for welding with the tab.
10. The connecting member according to claim 9, wherein the tab welding region is located at an end of the main body portion remote from the electrode terminal welding portion.
11. A connecting member according to any one of claims 1 to 10, wherein the thickness of different regions of the body portion is equal.
12. The connecting member according to any one of claims 1 to 11, wherein the connecting portion surrounds the electrode terminal welding portion, and the main body portion surrounds the connecting portion.
13. A battery cell comprising:

    an electrode terminal;

    an electrode assembly including a tab;

    the connection member according to any one of claims 1 to 12, for achieving electrical connection between the electrode terminal and the tab.
14. A battery, comprising:

    a plurality of battery cells comprising the connecting member according to any one of claims 1 to 12.
15. A powered device, comprising:

    a battery for providing electrical energy to the powered device, the battery comprising a connection member as claimed in any one of claims 1 to 12.