CN219303893U - Battery monomer, battery and power consumption device - Google Patents

Abstract

The application provides a battery monomer, a battery and an electricity utilization device. The battery cell includes an electrode assembly, a case, and a current collecting member. The electrode assembly includes a first tab; the case is used for accommodating the electrode assembly; the current collecting component is accommodated in the shell and is electrically connected with the first tab, and the current collecting component is welded with the shell.

Description

Battery monomer, battery and power consumption device

Technical Field

The application relates to the technical field of batteries, in particular to a battery monomer, a battery and an electric device.

Background

Energy conservation and emission reduction are key to sustainable development of the automobile industry, and electric vehicles become an important component of sustainable development of the automobile industry due to the energy conservation and environmental protection advantages of the electric vehicles. For electric vehicles, battery technology is an important factor in the development of the electric vehicles.

In some cases, the battery employs a current collecting member electrically connected with the electrode assembly to draw out and transmit electric energy to the electric device, but the current collecting member is located inside the battery case, the connection structure and the connection manner thereof face many limitations, and the current collecting member and the connection structure thereof in the battery are continuously optimized to achieve efficient and reliable connection, which is significant for the quality and performance of the battery.

Disclosure of Invention

The present application aims to solve at least one of the technical problems existing in the prior art. Therefore, an object of the present application is to provide a battery cell, a battery and an electric device, so as to improve the connection reliability of the current collecting member.

Embodiments of the first aspect of the present application provide a battery cell comprising: an electrode assembly, a case, and a current collecting member. The electrode assembly includes a first tab; the case is used for accommodating the electrode assembly; the current collecting component is accommodated in the shell and is electrically connected with the first tab, and the current collecting component is welded with the shell.

Through the electric connection of current collecting member and first utmost point ear respectively and the welded connection of casing, can realize stable electric current conduction and connect, improve the reliability of electrode connection.

In some embodiments, the current collecting member includes a first connection portion and a second connection portion. The first connecting part is used for being electrically connected with the first tab; the second connecting portion is connected with the first connecting portion, the second connecting portion is arranged along the edge of the first connecting portion and protrudes in a direction away from the electrode assembly, and the second connecting portion is connected with the shell in a welding mode and forms a first welding portion. The welding positions of the current collecting component and the first tab and the welding positions of the current collecting component and the shell can be effectively separated through the welding of the first connecting part and the second connecting part with the first tab and the shell, so that the cross influence during welding is avoided. The second connecting portion extends along a plane different from the plane where the first connecting portion is located, and can be better positioned in a face-to-face connection with the inner side of the shell, so that welding quality is improved.

In some embodiments, the thickness of the second connection part in the direction perpendicular to the axial direction of the electrode assembly is t1, and the height of the second connection part in the axial direction of the electrode assembly is h0, and satisfies: h0/t1 is more than or equal to 2 and less than or equal to 6. The dimension of the second connecting part is reasonably selected, so that the dimension requirement of the laser welding on the second connecting part along the axial direction X of the electrode assembly and the energy density of the battery cell can be better considered.

In some embodiments, the thickness of the second connection part in a direction perpendicular to the axial direction of the electrode assembly is t1,0.1 mm.ltoreq.t1.ltoreq.0.5 mm. The strength and the overcurrent capacity of the current collecting member can be considered by selecting a proper thickness of the second connecting part.

In some embodiments, the outer side of the second connection portion is an interference fit with the inner side of the housing. Through setting up second connecting portion and casing interference fit, the current collecting member installs to the inside back of casing, does not have the clearance between the lateral surface of second connecting portion and the medial surface of casing for current collecting member and casing can fasten to link to each other, connect the reliability height, simultaneously can reduce the rosin joint that leads to because of the clearance is too big and leak and damage electrode assembly because of laser leakage when welding, be favorable to guaranteeing welding quality.

In some embodiments, the second connection portion includes a plurality of protrusions circumferentially spaced along an inner wall of the housing, and a notch portion between two adjacent protrusions; the plurality of protruding parts are welded with the shell to form a plurality of first welding parts. The design can make the protruding part have certain deformability when installing, has taken into account the structural strength of mass flow component and the feasibility of installation location better.

In some embodiments, the plurality of protrusions are evenly spaced around the central axis of the electrode assembly. The structural design ensures that the formed first welding part between the current collecting component and the shell maintains a symmetrical structure, can enhance the shock resistance of welding, and is beneficial to avoiding welding cracking caused by uneven stress when being impacted by external force.

In some embodiments, the height of the protruding portion of the second connection portion in the axial direction of the electrode assembly is h0, and the height of the notch portion in the axial direction of the electrode assembly is h1, h 1. Ltoreq.h0. The height of the notch is reasonably selected, so that the overall strength and deformability of the second connecting part can be considered, and the assemblability of the current collecting member is improved.

In some embodiments, the projected length of the first weld along the axial direction of the electrode assembly 22 is a first length L1, the projected perimeter of the inner side surface of the case along the axial direction of the electrode assembly is a second length L2, and the first length L1 and the second length L2 satisfy: l1 is more than or equal to 0.5 xL 2. The first length L1 and the second length L2 are set to meet the requirements, so that effective welding length can be ensured, and further the reliability of welding connection is realized.

In some embodiments, the first connection portion is welded with the first tab to form a second weld. The adoption of the welding mode to form the second welding part can fixedly connect the current collecting component and the electrode assembly together, so that the overall strength of the battery is improved.

In some embodiments, the first connection part includes a first side facing the electrode assembly and a second side facing away from the electrode assembly, at least one of the first side and the second side being provided with a reinforcing rib for reinforcing the first connection part. The reinforcing ribs protruding from the plane of the first connecting part of the current collecting member can enhance the deformation resistance of the current collecting member.

In some embodiments, at least one reinforcing rib located on the first side surface is disposed corresponding to the first tab to form a second welding portion. The reinforcing rib can be abutted against the first tab when the current collecting component and the electrode assembly are aligned, the gap between the reinforcing rib and the first tab can be reduced to cause cold welding, the welding quality of the second welding part is ensured, and the strength of the current collecting component can be further enhanced by the second welding part formed by welding.

In some embodiments, the reinforcing rib for forming the second welding part is a punched groove protruding toward the electrode assembly, and a side of the punched groove facing away from the electrode assembly is recessed in the second side. The stamping groove is formed in the first connecting portion in a stamping mode to serve as the reinforcing rib, the process is simple, the cost is controllable, the weight of the current collecting member cannot be increased, the recess on one side, facing away from the electrode assembly, can be used for indicating the welding position for forming the second welding portion, and the welding positioning is facilitated to be simplified.

In some embodiments, the number of punched slots is greater than or equal to three. By setting a suitable number of second welds, a more secure structural connection and a better overcurrent capability can be achieved.

In some embodiments, the plurality of stamped grooves are evenly spaced along a circumference of the center of the first connection portion. The current of the electrode assembly can be uniformly transmitted to each part of the current collecting member through the second welding part, so that the uniformity of electric energy transmission is further improved, and the abnormal temperature rise of the current flowing through the local position of the current collecting member is restrained.

In some embodiments, the stamped grooves are a plurality of radially extending spoke-like patterns or a plurality of crescent-like patterns. The second welding portion regular pattern can guide the current to a position of the current collecting member near the central region and can guide the current to an edge of the current collecting member near the inner side surface of the case, so that the current collecting member can uniformly conduct the electric power.

In some embodiments, the connection of the second connection portion and the first connection portion is formed with a chamfer or a radius. By chamfering or rounding the transition, stress concentration at the junction can be reduced, and ease of installation of the current collecting member into the housing can also be provided.

In some embodiments, the thickness of the first connection part in the axial direction of the electrode assembly is t2, and 0.1 mm.ltoreq.t2.ltoreq.0.5 mm. Through selecting suitable thickness of first connecting portion, can make the mass flow component compromise welding requirement, overflow ability and intensity requirement better.

In some embodiments, the housing includes an open end face forming an opening, and the battery cell further includes an end cap including an end cap body and a lap joint portion surrounding an outer edge of the end cap body, the lap joint portion being connected with the open end face to cover the opening. The shell is sealed by arranging the end cover, so that the sealing performance and the safety performance of the battery monomer are improved, and meanwhile, the current collecting component is prevented from being directly impacted by external force.

In some embodiments, the thickness C1 of the overlap and the thickness C2 of the end cap body satisfy C1.ltoreq.C2 in the axial direction of the electrode assembly. The thickness of different positions of the end cover can be reasonably designed, and the energy density of the battery monomer and the structural strength of the end cover can be considered simultaneously.

In some embodiments, the overlap has a thickness C1 of 0.2mm C1 0.5mm and the end cap body has a thickness C2 of 0.3mm C2 0.7mm. The value range of the end cover of the embodiment can better give consideration to the energy density of the battery monomer and the structural strength of the end cover.

In some embodiments, the case includes a body portion and a welding portion connected to each other, the body portion surrounds the outside of the electrode assembly, the welding portion is located at one end of the body portion near the opening, the opening end face is located at one end of the welding portion far away from the electrode assembly, and the second connection portion is welded to the welding portion to form a first welded portion. By forming the first welded portion after welding and melting the current collecting member with the welded portion near the open end of the case, the internal resistance can be reduced while achieving the sealed connection, thereby achieving the conductive connection.

In some embodiments, an end surface of the second connection portion remote from the first connection portion is lower than the opening end surface. The end face of the second connecting part is lower than the opening end face, so that a certain space for accommodating welding deformation is provided when the first welding part is formed by welding, and the influence of the welding deformation on the installation of subsequent components is relieved.

In some embodiments, an end surface of the second connection portion remote from the first connection portion is flush with the open end surface. Therefore, the butt joint length of the welding part of the second connecting part and the shell along the axial direction of the electrode assembly can be increased as much as possible, and enough welding space is provided between the second connecting part and the welding part to form a first welding part, so that the welding forming quality of the first welding part is improved.

In some embodiments, the first weld is configured as a penetration weld formed by laser penetrating the second connection and melting at least a portion of the weld. Thus, the welding can be beneficial to avoiding the electrode damage caused by the laser emitted to the electrode assembly during the welding, and improving the safety of the welding operation.

In some embodiments, the first weld is configured as a butt weld formed by directing laser light at a butt location of the second connection and the weld. The laser has sufficient arrangement space outside the battery during butt welding, is favorable to improving laser welding's precision, and then improves welding quality, can reduce the length that second connecting portion and welded part are followed electrode assembly's axial direction laminating through butt welding simultaneously to reduce the inner space that occupies the battery case.

In some embodiments, the side of the overlap facing the current collecting member is provided with a groove, which is disposed in correspondence with the first weld. The arrangement of the groove can form a space for accommodating the first welding part, so that the problem that the end cover and the shell cannot meet the assembly requirement due to the first welding part is avoided.

In some embodiments, the inner diameter of the body portion is less than the inner diameter of the weld. The inner diameter of the welding part is larger than that of the main body part, so that the installation space of the current collecting member can be increased, and the assembly connection of the current collecting member and the shell is facilitated.

In some embodiments, the junction of the body portion and the weld forms a stepped surface against which the current collecting member abuts. The internal diameters of the main body part and the welding part are different, so that a step surface is formed at the joint of the inner side surfaces of the main body part and the welding part, the current collecting member can be positioned through the step surface, more convenient butt joint positioning is realized, and the assembly efficiency is improved.

In some embodiments, the wall thickness of the body portion is equal to the wall thickness of the weld. This can maintain the strength of the case while forming the stepped portion to better position the current collecting member.

In some embodiments, the outer side of the body portion is coplanar with the outer side of the weld. The outer side face of the main body part and the outer side face of the welding part are coplanar, so that the consistency of the sizes of the outer surfaces of the battery cells can be maintained, and the combination and the assembly of a plurality of battery cells are facilitated.

In some embodiments, the inner diameter D1 of the welded portion and the inner diameter D2 of the main body portion in a direction perpendicular to the axial direction of the electrode assembly satisfy: D1-D2 is more than or equal to 0.1mm. The internal dimensions of the housing of this embodiment may be such that the stepped surface is formed with a width to accommodate the current collecting member to better provide positioning for the installation of the current collecting member.

In some embodiments, the current collecting member includes a first material layer and a first soldering flux layer, the first material layer and the first soldering flux layer are made of different materials, and the first soldering flux layer is located on a surface of the first material layer facing the housing. The welding assisting layer is arranged on the surface of the welding so as to assist welding, so that the welding quality is improved, and the occurrence of cracks in welding printing is avoided.

In some embodiments, the housing includes a second material layer and a second soldering flux layer, the second material layer being different from the second soldering flux layer, the second soldering flux layer being located on a side surface of the second material layer facing the current collecting member. Therefore, the forming quality of the welding marks can be further improved, and the stability and the reliability of welding connection are improved.

In some embodiments, the first material layer is copper, and the second material layer is carbon steel. The first material layer of the current collecting member is made of copper with high conductivity, so that current collection can be better realized, and the internal resistance of the battery is reduced. The second material layer of the shell is made of carbon steel, so that the structural strength and the conductivity can be both achieved.

In some embodiments, the material of the first soldering flux layer and the material of the second soldering flux layer are nickel. The nickel is used as the welding auxiliary layer, so that the welding quality can be improved in an auxiliary manner, and the occurrence of cracks can be avoided.

In some embodiments, the first weld overlay has a thickness u1 and the second weld overlay has a thickness u2, wherein 1 um.ltoreq.u1+u2.ltoreq.9um. By optimizing the thickness of the weld assist layer, the weight of the end cover and the shell can be controlled while assisting in welding, and unnecessary weight loss is reduced.

In some embodiments, the electrode assembly further includes a second tab having a polarity different from the polarity of the first tab; the battery cell also comprises an electrode terminal, wherein the electrode terminal is positioned at one end of the shell far away from the opening and is electrically connected with the second lug.

An embodiment of a second aspect of the present application provides a battery, including the battery cell in the above embodiment.

An embodiment of a third aspect of the present application provides an electrical device, including the battery of the above embodiment, where the battery is configured to provide electrical energy.

The foregoing description is only an overview of the technical solutions of the present application, and may be implemented according to the content of the specification in order to make the technical means of the present application more clearly understood, and in order to make the above-mentioned and other objects, features and advantages of the present application more clearly understood, the following detailed description of the present application will be given.

Drawings

In the drawings, the same reference numerals refer to the same or similar parts or elements throughout the several views unless otherwise specified. The figures are not necessarily drawn to scale. It is appreciated that these drawings depict only some embodiments according to the disclosure and are not therefore to be considered limiting of its scope.

FIG. 1 is a schematic illustration of a vehicle according to some embodiments of the present application;

fig. 2 is an exploded view of a battery according to some embodiments of the present application;

fig. 3 is a schematic structural view of a battery cell according to some embodiments of the present application;

fig. 4 is a front view of a battery cell according to some embodiments of the present application;

FIG. 5 is a schematic cross-sectional view of the battery cell shown in FIG. 4 along the A-A direction;

FIG. 6 is a partial enlarged view at B in FIG. 5;

FIG. 7 is a cross-sectional view of the battery cell shown in FIG. 4, with the end cap omitted, taken along the direction A-A;

FIG. 8 is an enlarged view of a portion of FIG. 7 at C;

fig. 9 is a schematic structural view of a current collecting member according to some embodiments of the present application;

fig. 10 is a cross-sectional view of a current collecting member according to some embodiments of the present application;

fig. 11 is a schematic structural view of a current collecting member connected to a first tab according to some embodiments of the present disclosure;

fig. 12 is a schematic structural view of a current collecting member connected to a first tab according to other embodiments of the present disclosure;

FIG. 13 is an enlarged view of a portion of FIG. 7 at C in another embodiment;

FIG. 14 is an enlarged view of a portion of FIG. 7 at C in yet another embodiment;

fig. 15 is a partial enlarged view at B in fig. 5 in another embodiment.

Reference numerals illustrate:

a vehicle 1000;

battery 100, controller 200, motor 300;

a case 10, a first portion 11, a second portion 12;

the battery cell 20, the case 21, the end wall 211, the open end face 212, the body portion 213, the welding portion 214, the second material layer 215, the second welding flux 216, the electrode assembly 22, the tab 221, the first tab 221A, the second tab 221B, the current collecting member 23, the rib 231, the first connection portion 232, the second connection portion 233, the boss 2331, the notch 2332, the first material layer 234, the first welding flux 235, the end cap 24, the end cap body 241, the abutting portion 242, the lap joint 243, the groove 2421, the second welding portion 25, the first welding portion 26, the electrode terminal 27.

Detailed Description

Embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical solutions of the present application, and thus are only examples, and are not intended to limit the scope of protection 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 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.

In the description of the embodiments of the present application, the technical terms "first," "second," etc. are used merely to distinguish between different objects and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

Reference herein 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 present 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 appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, which means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

In the description of the embodiments of the present application, the term "plurality" 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 description of the embodiments of the present application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the embodiments of the present application.

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like are to be construed broadly and may, for example, be fixedly connected, detachably connected, or be integrated; or may be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to the specific circumstances.

Currently, the application of power batteries is more widespread from the development of market situation. The power battery is not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles, and the like, and a plurality of fields such as military equipment, aerospace, and the like. With the continuous expansion of the application field of the power battery, the market demand of the power battery is also continuously expanding.

The electrode assembly within the battery needs to be electrically connected to the case so that the case can serve as an electrode lead-out electrode, which can be used to input or output electric power. In order to enable the shell to be conveniently and electrically connected with the electrode assembly in the battery unit, a current collecting member is further arranged in the battery unit shell, the current collecting member is positioned on one side of the electrode assembly, facing the end cover of the battery unit, of the electrode assembly, the electrode assembly is electrically connected with the end cover through the current collecting member, and the end cover covers the opening of the shell and is electrically connected with the shell. Thus, the electrode assembly, the current collecting member, the end cap, and the case are sequentially connected as a conductive path.

The applicant notes that the connection between the current collecting member, the end cap and the battery case is usually a welded connection, and because of the limited space, the positioning accuracy and the size requirements of the members during welding are high, if the positioning deviation is large, or the sizes are not matched, there may be a risk of welding through, or the welding quality is poor, resulting in insufficient effective welding length and affecting the welding strength.

In order to realize reliable connection of the current collecting member in the battery, the applicant researches and discovers that the connection structure of the current collecting member and the shell can be optimized in design, so that the positioning precision of the current collecting member is improved, and the welding quality between the current collecting member and the battery shell and between the end cover and the battery shell is improved. The size of the current collecting member and the connection structure of the current collecting member, the end cover, the shell and the tab can be optimally designed, so that the welding quality of the welding connection of the current collecting member is improved, and the structural strength is enhanced.

The battery cell disclosed by the embodiment of the application can be used in electric devices such as vehicles, ships or aircrafts, but is not limited to the electric devices. The power supply system with the battery cells, batteries and the like disclosed by the application can be used for forming the power utilization device, so that the stability of the battery performance and the service life of the battery are improved.

The embodiment of the application provides an electricity utilization device using a battery as a power supply, wherein the electricity utilization device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft and the like. Among them, the electric toy may include fixed or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric plane toys, and the like, and the spacecraft may include planes, rockets, space planes, and spacecraft, and the like.

For convenience of description, the following embodiment will take an electric device according to an embodiment of the present application as an example of the vehicle 1000.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a vehicle 1000 according to some embodiments of the present application. The vehicle 1000 may be a fuel oil vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or a range-extended vehicle. The battery 100 is provided in the interior of the vehicle 1000, and the battery 100 may be provided at the bottom or the head or the tail of the vehicle 1000. The battery 100 may be used for power supply of the vehicle 1000, for example, the battery 100 may be used as an operating power source of the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, the controller 200 being configured to control the battery 100 to power the motor 300, for example, for operating power requirements during start-up, navigation, and travel of the vehicle 1000.

In some embodiments of the present application, battery 100 may not only serve as an operating power source for vehicle 1000, but may also serve as a driving power source for vehicle 1000, instead of or in part instead of fuel oil or natural gas, to provide driving power for vehicle 1000.

Referring to fig. 2, fig. 2 is an exploded view of a battery 100 according to some embodiments of the present application. The battery 100 includes a case 10 and a battery cell 20, and the battery cell 20 is accommodated in the case 10. The case 10 is used to provide an accommodating space for the battery cell 20, and the case 10 may have various structures. In some embodiments, the case 10 may include a first portion 11 and a second portion 12, the first portion 11 and the second portion 12 being overlapped with each other, the first portion 11 and the second portion 12 together defining an accommodating space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one end opened, the first portion 11 may be a plate-shaped structure, and the first portion 11 covers the opening side of the second portion 12, so that the first portion 11 and the second portion 12 together define a containing space; the first portion 11 and the second portion 12 may be hollow structures each having an opening at one side, and the opening side of the first portion 11 is engaged with the opening side of the second portion 12. Of course, the case 10 formed by the first portion 11 and the second portion 12 may be of various shapes, such as a cylinder, a rectangular parallelepiped, or the like.

In the battery 100, the plurality of battery cells 20 may be connected in series, parallel or a series-parallel connection, wherein the series-parallel connection refers to that the plurality of battery cells 20 are connected in series or parallel. The plurality of battery cells 20 can be directly connected in series or in parallel or in series-parallel, and then the whole formed by the plurality of battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting a plurality of battery cells 20 in series or parallel or series-parallel connection, and a plurality of battery modules are then connected in series or parallel or series-parallel connection to form a whole and are accommodated in the case 10. The battery 100 may further include other structures, for example, the battery 100 may further include a bus member for making electrical connection between the plurality of battery cells 20.

Wherein each battery cell 20 may be a secondary battery or a primary battery; but not limited to, lithium sulfur batteries, sodium ion batteries, or magnesium ion batteries. The battery cell 20 may be in the shape of a cylinder, a flat body, a rectangular parallelepiped, or other shapes, etc.

Fig. 3 is a schematic structural view of a battery cell according to some embodiments of the present application, fig. 4 is a front view of the battery cell shown in fig. 3, fig. 5 is a schematic sectional view of the battery cell shown in fig. 4 along A-A direction, fig. 6 is a partially enlarged view of the battery cell shown in fig. 5B, and fig. 7 is a sectional view of the battery cell shown in fig. 4 along A-A direction after omitting an end cap; fig. 8 is a partial enlarged view at C in fig. 7. According to some embodiments of the present application, referring to fig. 3 to 8, the battery cell 20 refers to the smallest unit constituting the battery 100, and the battery cell 20 includes a case 21, an electrode assembly 22, and a current collecting member 23. The electrode assembly 22 has a tab 221, the tab 221 includes a first tab 221A and a second tab 221B, the case 21 defines an accommodating space and an opening at one end of the accommodating space, the accommodating space is used for accommodating the electrode assembly 22, and the current collecting member 23 is electrically connected with the first tab 221A and welded with the case 21.

The case 21 has a hollow structure, and an accommodating space for accommodating the electrode assembly 22 is formed inside, and the case 21 has an opening and an opening end surface surrounding the opening, and the case 21 can be filled with an electrolyte. The shape and size of the case 21 are adapted to those of the electrode assembly 22, and for a cylindrical battery cell 20, both the electrode assembly 22 and the case 21 may be cylindrical, and for a square battery cell 20, both the electrode assembly 22 and the case 21 may be square. The material of the housing 21 may be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiment of the present application is not limited thereto.

The electrode assembly 22 is a component in which an electrochemical reaction occurs in the battery cell 20, and the electrode assembly 22 may include a body portion and tabs 221, the tabs 221 extending from the body portion such that the tabs 221 protrude from an end of the body portion. The electrode assembly 22 may include a positive electrode tab, a negative electrode tab, and a separator. The electrode assembly 22 may be a wound structure formed by winding a positive electrode tab, a negative electrode tab, and a separator. The electrode assembly 22 may be a stacked structure formed by stacking a positive electrode tab, a negative electrode tab, and a separator. The positive electrode plate comprises a positive electrode current collector and positive electrode active material layers coated on two opposite sides of the positive electrode current collector. The negative electrode plate comprises a negative electrode current collector and negative electrode active material layers coated on two opposite sides of the negative electrode current collector. The body portion is a portion of the electrode assembly 22 corresponding to a region of the electrode sheet coated with the active material layer, and the tab 221 is a portion of the electrode sheet not coated with the active material layer.

The tab 221 may be divided into a first tab 221A and a second tab 221B, where the first tab 221A is convexly connected to the first pole piece, and the second tab 221B is convexly connected to the second pole piece. The first tab 221A and the second tab 221B are respectively connected with different electrode lead-out poles for inputting or outputting electric energy. For example, the first tab 221A may be connected to the current collecting member 23 to electrically connect the current collecting member 23 to the case 21, and the second tab 221B may be electrically connected to the electrode terminal 27, and the electrode terminal 27 and the case 21 are insulated from each other, so that the case 21 and the electrode terminal 27 serve as electrode lead-out poles having different polarities on the battery cell 20, respectively, for inputting or outputting electric power.

The first tab 221A and the second tab 221B may be located at the same end of the electrode assembly 22 or may be located at different ends of the electrode assembly 22. One of the first tab 221A and the second tab 221B is a positive tab, and the other is a negative tab. If the first tab is a positive tab and the second tab is a negative tab, the case 21 is a positive electrode lead-out electrode, and the electrode terminal 27 is a negative electrode lead-out electrode; if the first tab is a negative tab and the second tab is a positive tab, the case 21 is a negative electrode lead-out electrode, and the electrode terminal 27 is a positive electrode lead-out electrode.

The current collecting member 23 may be made of conductive materials such as copper, iron, etc. The current collecting member 23 is electrically connected to the first tab 221A and is welded to the housing 21, so as to collect the current of the first pole piece and then conduct the current to the housing 21.

According to the embodiment of the application, the current collecting member 23 is respectively connected with the first tab 221A and the shell 21 in a conductive manner, so that current generated by the first pole piece in the electrode assembly 22 can be conducted to the shell 21, stable conductive connection can be realized by welding connection between the current collecting member 23 and the shell 21, and reliability of electrode connection is improved.

In some embodiments, as shown in fig. 5-8, the current collecting member 23 includes a first connection portion 232 and a second connection portion 233 connected to each other, and the first connection portion 232 is electrically connected to the first tab 221A; the second connection part 233 is disposed along an edge of the first connection part 232 and protrudes in a direction away from the electrode assembly 22, and the second connection part 233 is welded to the case 21 and forms the first welded part 26.

The shape of the first connection part 232 corresponds to the shape of the case 21 and the electrode assembly 22, and for the cylindrical case 21, the electrode assembly 22 is circular, and the first connection part 232 is correspondingly circular. The first connection part 232 and the second connection part 233 may be manufactured as one piece by an integral molding process, so that an assembling process of the first connection part 232 and the second connection part 233 is omitted, and the structural strength of the current collecting member 23 may be improved without increasing costs. The second connection parts 233 are disposed along edges of the first connection parts 232 and protrude in a direction away from the electrode assembly 22 such that the second connection parts 233 are configured such that the first connection parts 232 extend in different directions, respectively. For example, the second connection portion 233 may be formed by bending the plate body structure such that an edge of the plate body structure is bent. In one example, the second connection portion 233 and the first connection portion 232 form an angle of 90 °, and the side surface of the second connection portion 233 is parallel to the inner side surface of the housing 21, so that the two can be better aligned during welding connection.

According to the embodiment of the present application, the welding of the current collecting member 23 and the first tab 221A and the welding of the current collecting member 23 and the housing 21 can be effectively separated from each other by welding the first and second connection parts 232 and 233 with the first tab 221A and the housing 21, respectively, so as to avoid the cross influence at the time of welding. The second connection portion 233 extends along a plane different from the plane of the first connection portion 232, and can be better positioned to face the inner side of the housing 21, which is beneficial to improving welding quality.

In some embodiments, as shown in fig. 8, the thickness of the second connection part 233 in the direction perpendicular to the axial direction of the electrode assembly 22 is t1, and the height of the second connection part 233 in the axial direction X of the electrode assembly 22 is h0, t1 and h0 satisfy: h0/t1 is more than or equal to 2 and less than or equal to 6.

It will be appreciated that there are a number of situations for h0/t1 when h0/t1< 2. In the case that h0/t1<2 is 1.ltoreq.h0, where the value of h0 is smaller, so that when laser is projected between the second connection portion 233 and the inner side of the case 21 along the axial direction X of the electrode assembly 22 to form the first welded portion 26 by welding, the laser is easily projected to the side of the first connection portion 232 facing away from the electrode assembly 22, resulting in partial melting of the connection portion between the second connection portion 233 and the first connection portion 232, and a narrow slit exists between the outer side of the connection portion having a chamfer structure and the inner side of the case 21, the laser can be emitted to the electrode assembly 22 through the narrow slit, resulting in the electrode assembly 22 being hit and damaged; another case is that h0/t1< 1, meaning that h0 < t1, where h0 has a smaller value, the risk of damage to the electrode assembly 22 by laser light is greater.

When h0/t1 > 6, it means that h0 > 6t1, where the value of h0 is too large, and thus, the second connection portion 233 occupies too much space inside the case 21 along the axial direction X of the electrode assembly 22, the number of the electrode sheets that can be accommodated inside the battery cell 20 is small, and the energy density of the battery cell 20 is low.

Through a great deal of experimental analysis of the applicant, it is found that when the ratio h0/t1 of h0 to t1 is greater than or equal to 2 and less than or equal to 6, the value of h0 is moderate, if the laser projects between the second connecting portion 233 and the inner side surface of the casing 21 along the axial direction X of the electrode assembly 22 to form the first welding portion 26 by welding, the possibility that the connection portion between the second connecting portion 233 and the first connecting portion 232 is hit by the laser to be melted is reduced, so that the risk that the laser is damaged by the narrow slit between the connection portion of the chamfer structure and the inner side surface of the casing 21 is reduced. Meanwhile, the space occupied by the second connection part 233 in the axial direction X of the electrode assembly 22 inside the case 21 is reduced as much as possible, so that the number of the electrode tabs that can be accommodated inside the battery cell 20 is increased without changing the total height of the battery cell 20, thereby facilitating the increase of the active material capacity of the battery cell 20, and thus the energy density of the battery cell 20 can be increased.

In some embodiments, h0/t1 may be further designed to be 3.ltoreq.h0/t 1.ltoreq.5. Through a great deal of experimental analysis by the applicant, when the relation between h0 and t1 satisfies that the relation is not less than 3 and not more than 0/t1 and not more than 5, the value of h0 is more proper, and the dimensional requirement of the laser welding on the second connecting part 233 along the axial direction X of the electrode assembly 22 and the energy density of the battery cell 20 can be better considered.

In some embodiments, the thickness t1 of the second connection part 233 in the direction perpendicular to the axial direction of the electrode assembly 22 satisfies 0.1 mm.ltoreq.t1.ltoreq.0.5 mm.

In some embodiments, t1 may be further designed to be 0.2 mm.ltoreq.t1.ltoreq.0.4 mm. The strength and the overcurrent capacity of the current collecting member 23 can be compatible by selecting an appropriate thickness of the second connection portion 233.

In some embodiments, the outer side of the second connection 233 is an interference fit with the inner side of the housing 21.

The present embodiment is particularly applicable to a case where the housing 21 is cylindrical, the first connecting portion 232 is correspondingly circular, and the second connecting portion 233 is of a ring-shaped structure.

Through setting up second connecting portion 233 and casing 21 interference fit, after the mass flow component 23 installs inside casing 21, there is not the clearance between the medial surface of second connecting portion 233 and casing 21 for mass flow component 23 and casing 21 can fasten to link to each other, connect the reliability height, can reduce simultaneously and leak welding and laser leakage damage electrode assembly because of the too big rosin joint that leads to in clearance when welding, be favorable to guaranteeing welding quality.

Fig. 9 is a schematic structural view of a current collecting member according to some embodiments of the present application; fig. 10 is a cross-sectional view of a current collecting member according to some embodiments of the present application. In some embodiments, as shown in fig. 9, the second connection part 233 includes a plurality of protruding parts 2331 protruding in a direction away from the electrode assembly 22, which are disposed at intervals, and a notch part 2332 located between adjacent two of the protruding parts 2331; the plurality of bosses 2331 are welded to the housing 21 to form a part of the first welded portion 26, respectively.

The number of the protrusions 2331 is not limited, and for example, the protrusions 2331 may be provided with one or more. When the protruding portion 2331 is provided with a plurality of protruding portions, the second connecting portion 233 is divided into a plurality of arc-shaped connecting sections arranged at intervals, and the height of the notch portion 2332 is smaller than that of the protruding portion 2331, so that a notch is formed between two adjacent protruding portions 2331.

The design can make the protruding part 2331 have certain deformability during installation, especially when the second connecting part 233 is in interference fit with the inner side surface of the shell 21, so that the structural strength of the current collecting member 23 and the feasibility of installation and positioning are better considered.

In some embodiments, the plurality of protrusions 2331 are uniformly distributed centering around the central axis of the electrode assembly 22.

It will be appreciated that the plurality of protrusions 2331 are uniformly spaced apart such that the first weld 26 formed by welding the protrusions 2331 to the housing 21 is also a plurality of arcuate welds of equal length uniformly distributed circumferentially. The structural design ensures that the formed first welding part 26 between the current collecting member 23 and the shell 21 maintains a symmetrical structure, can enhance the shock resistance of welding, and is beneficial to avoiding welding fracture caused by uneven stress when being impacted by external force.

In some embodiments, as shown in FIG. 10, the height of the protruding portion 2331 of the second connection portion 233 is h0, and the height of the notch portion 2332 is h1, h 1. Ltoreq.h0, along the axial direction X of the electrode assembly 22.

The height of the boss 2331 refers to the height at which the end surface of the boss 2331 remote from the first connection part 232 protrudes with respect to one side surface of the first connection part 232 where it is located in the axial direction X of the electrode assembly 22. The height of the notch 2332 refers to the height of the empty portion, and may be greater than 0 and less than or equal to the height of the protrusion 2331, i.e., the notch 2332 may have a structure protruding from the surface of the side of the first connection part 232 remote from the electrode assembly, but the protruding height is smaller than the protrusion 2331. In one example, the height of the notch 2332 is the same as the height of the boss 2331, where the surface of the notch 2332 is flush with the surface of the side of the first connection 232 remote from the electrode assembly.

The height of the notch 2332 is less than or equal to the height of the boss 2331, so that the structure between two adjacent bosses 2331 is broken, thereby increasing the deformability of the boss 2331 and facilitating the fitting alignment with the housing 21. The reasonable selection of the height of the notch 2332 can give consideration to the overall strength and deformability of the second connecting part, and the assemblability of the current collecting member is improved.

In some embodiments, the projected length of the first welding portion 26 along the axial direction X of the electrode assembly 22 is a first length L1, the projected perimeter of the inner side surface of the case 21 along the axial direction X of the electrode assembly 22 is a second length L2, and the first length L1 and the second length L2 satisfy: l1 is more than or equal to 0.5 xL 2.

The first length L1 is the length of the first welded portion 26, and when the first welded portion 26 includes a plurality of welds arranged at intervals, the first length L1 is the cumulative length of the plurality of welds. It will be appreciated that since the first weld 26 is welded and fused along the inner side of the housing 21, the first length L1 and the second length L2 are equal when the first weld 26 is provided for a full turn. Considering that a missing welding or a false welding may occur at the time of welding, an actual welding length may not reach a preset length, or a first welded portion 26 having a multi-stage welding is formed by a segment welding such that a first length L1 of the first welded portion 26 is smaller than a second length L2, and since the welding length directly relates to the connection strength of the current collecting member and the case, the first length is too small to deteriorate the connection reliability of the current collecting member 23 and the case 21, and the impact resistance becomes weak.

The first length L1 and the second length L2 are set to be L1 more than or equal to 0.5 multiplied by L2, so that the effective welding length can be ensured, and the reliability of welding connection is further realized.

Fig. 11 is a schematic structural view of a current collecting member connected to a first tab according to some embodiments of the present disclosure; fig. 12 is a schematic structural view of a current collecting member connected to a first tab according to other embodiments of the present application. Referring to fig. 11-12, in some embodiments, the first connection portion 232 is welded with the first tab 221A to form the second weld 25.

The first connection portion 232 is electrically connected to the first tab 221A by welding, thereby collecting the current of the electrode tab to the current collecting member 23 and conducting it to the case 21. The welding may be laser welding or ultrasonic welding, and in some examples, the second welding portion 25 may be formed by penetrating the first connection portion 232 by laser light emitted in the axial direction of the electrode assembly and melting the first tab 221A, and finally solidifying.

The welding manner of forming the second welding portion 25 can fixedly connect the current collecting member 23 and the electrode assembly 22 together, improves the overall strength of the battery, and can realize stable conductive connection between the current collecting member 23 and the electrode assembly 22 even in the face of external impact.

In some embodiments, the first connection 232 includes a first side facing the electrode assembly 22, and a second side facing away from the electrode assembly 22; at least one of the first side and the second side is provided with at least one reinforcing rib 231 protruding from the surface thereof, and the reinforcing rib 231 is used for reinforcing the current collecting member 23.

The current collecting member 23 is generally made of a material having high conductivity, such as copper, and has a low strength, and is easily deformed by an external force, thereby affecting the conductive connection between the current collecting member 23 and the first tab 221A and the case 21. Providing the reinforcing ribs 231 protruding from the plane of the first connection portion of the current collecting member 23 may enhance the deformation resistance of the current collecting member 23. The reinforcing ribs 231 may be provided on the first side surface, the second side surface, or both sides, and the number of the reinforcing ribs 231 is not limited, and may be one or more.

In some embodiments, at least one reinforcing rib 231 located at the first connection part 232 facing the first side of the electrode assembly 22 is welded to the first tab 221A to form the second welded part 25.

Since the reinforcing rib 231 protrudes from the surface of the electrode assembly 22, the reinforcing rib 231 can be abutted against the first tab 221A when the current collecting member 23 is aligned with the electrode assembly 22, and the welding of the reinforcing rib 231 and the first tab 221A can reduce the cold joint caused by the gap between the reinforcing rib 231 and the first tab 221A, so that the welding quality of the second welding part 25 is ensured, and the strength of the current collecting member 23 can be further enhanced by the welded second welding part 25.

In some embodiments, as shown in fig. 9 and 10, the reinforcing rib 231 for forming the second welding part 25 is a punched groove, and a side of the punched groove facing away from the electrode assembly 22 is recessed from the second side of the first connecting part 232.

The punching groove is a portion formed by punching a plane of the first connecting portion and protruding integrally toward one side surface of the first connecting portion. The stamping method is adopted to prepare the stamping groove on the first connecting part 232 as the reinforcing rib, the process is simple, the cost is controllable, the weight of the current collecting member is not increased, the recess on the side facing away from the electrode assembly 22 can be used for indicating the welding position for forming the second welding part 25, and the simplification of welding positioning is facilitated.

In some embodiments, the number of second welds 25 is greater than or equal to three.

The greater the number of second welded portions 25 formed by welding, the better the structural strength, and a sufficient number of second welded portions 25 can provide more current passing channels, avoid overheating due to excessive current flux of a single weld, and improve the current passing capability of the current collecting member.

By defining a suitable number of second welds 25 in this embodiment, a more secure structural connection and superior overcurrent capability can be achieved.

In some embodiments, the second welding parts 25 are uniformly spaced along the circumference of the center of the first connecting part 232.

The number of the second welding parts 25 formed by welding may be plural, and a specific number may be arranged according to actual needs, and the plurality of second welding parts 25 may be uniformly spaced around the center of the first connection part 232, for example, four second welding parts 25 are formed between the current collecting member 23 and the first tab 221A, and the four second welding parts 25 are uniformly distributed around the central axis of the electrode assembly 22, as shown in fig. 11.

The electric power of the electrode assembly 22 in this embodiment can be uniformly transmitted to the current collecting member 23 through the second welding portion, further improving the uniformity of electric power transmission, and suppressing the abnormal temperature rise due to the excessive current flowing through the local position of the current collecting member 23.

In some embodiments, the second weld 25 is a plurality of radially extending spoke-like patterns or a plurality of crescent-like patterns.

In some examples, referring to fig. 11, the plurality of strip-shaped second welding parts 25 may be regarded as being radiated outward from the central position of the current collecting member 23. In this way, the second welding portion 25 can guide the current to a position of the current collecting member 23 near the central region and can guide the current to an edge of the current collecting member 23 near the inner side surface of the case 21, so that the current collecting member 23 can uniformly conduct the electric power.

In some examples, referring to fig. 12, the second welding portion 25 is integrally in a crescent shape, and may specifically include a first segment, an arc segment, and a second segment that are sequentially connected, where the first segment and the second segment are located on a side of the arc segment where the center of the circle is located, and a distance between the first segment and the second segment gradually increases from a side near the arc segment to another side far from the arc segment. Wherein the center of the arc segment is located at a side of the arc segment away from the central axis of the electrode assembly 22.

In this way, the second welding portion 25 can guide the current to the center position of the current collecting member 23 and can guide the current to the edge of the current collecting member 23 near the inner side surface of the case 21, so that the current collecting member 23 can uniformly conduct the electric power. Moreover, through the first section of design circular arc section connection and second section, circular arc section slick and sly transition, compare for the pointed end with the junction of first section and second section, can alleviate and appear stress concentration.

In some embodiments, a connection of the second connection portion 233 and the first connection portion 232 is formed with a chamfer or a radius.

By chamfering or rounding the transition, stress concentration at the junction can be reduced, and ease of installation of the current collecting member 23 into the housing 21 can also be provided.

In some embodiments, as shown in FIG. 8, the thickness of the first connection 232 in the axial direction of the electrode assembly 22 is t2, and 0.1 mm.ltoreq.t2.ltoreq.0.5 mm.

In one example, the thickness t2 of the first connection portion 232 may further satisfy 0.2mm < t2 > 0.4mm. In another example, the thickness t2 of the first connection portion 232 and the thickness t1 of the second connection portion 233 may be equal, so that the current collecting member 23 may be formed by a single piece, reducing manufacturing costs.

By selecting a suitable thickness of the first connection portion 232, the current collecting member 23 can better meet the welding requirement, the overcurrent capability and the strength requirement.

In some embodiments, as shown in fig. 5-8, the case 21 includes an open end surface 212 forming an opening, the battery cell 20 further includes an end cap 24, the end cap 24 includes an end cap body 241 and a lap portion 243 surrounding an outer edge of the end cap body 241, and the lap portion 243 is connected to the open end surface 212 such that the end cap 24 covers the opening.

The end cap 24 covers the opening to isolate the cavity within the housing 21 from the outside environment. Without limitation, the shape of the end cap 24 may be adapted to the shape of the housing 21 to fit the housing 21. The end cap 24 may be made of a material having a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.), so that the end cap 24 is not easily deformed when being extruded and collided, so that the battery cell 20 can have a higher structural strength, and the safety performance can be improved. In one example, the electrode terminal 27 may be located at one side of the opening of the case 21, for example, mounted on the end cap 24 in an insulating manner, and the first tab 221A and the second tab 221B are located at one end of the electrode assembly 22 facing the opening, such that one of the first tab 221A and the second tab 221B is electrically connected to the case 21 and the other is electrically connected to the electrode terminal 27 through the current collecting member 23. In this way, the first tab 221A and the second tab 221B are led out from the same end of the electrode assembly 22, and only the electric connection space is reserved at one end of the electrode assembly 22, and the electrode leading-out parts are not required to be respectively arranged at two ends of the battery cell 20, so that the overall energy density of the battery cell 20 can be effectively improved. As an alternative embodiment, as shown in fig. 5, the electrode terminal 27 may be mounted on the end wall 211 of the case 21 opposite to the opening, with the first tab 221A and the second tab 221B being located at different ends of the electrode assembly 22.

The end cover 24 is arranged to seal the shell 21, so that the sealing performance and the safety performance of the battery cell 20 are improved, and meanwhile, the current collecting member 23 is prevented from being directly impacted by external force.

In some embodiments, as shown in FIG. 6, the thickness C1 of overlap 243 and the thickness C2 of end cap body 241 satisfy C1.ltoreq.C2 in the axial direction X of electrode assembly 22.

The surface of the end cap body 241 facing away from the electrode assembly 22 and the surface of the overlap 243 facing away from the electrode assembly 22 may be set to be flush, so that the height of the battery cell 20 in the axial direction of the electrode assembly 22 is equal to the sum of the height of the case 21 in the axial direction of the electrode assembly 22 and the thickness C1 of the overlap 243, and the effective capacity in the battery case may be improved as much as possible. On this basis, since C1 < C2, the thickness C2 of the end cap body 241 in this embodiment may be larger, so that the structural strength of the end cap 24 may be improved, and at the same time, the thickness of the overlap portion 243 is thinner, so that the space occupied by the end case in the battery case may be reduced as much as possible.

It can be understood that when the end cover body 241 is provided with a notch groove for pressure relief, the notch groove may be thinned at the position where the notch groove is located to adapt to the pressure threshold of the pressure relief due to the pressure relief requirement, so that the thickness of the notch groove cannot truly reflect the strength of the end cover body, and the thickness C2 of the end cover body 241 in this embodiment refers to the thickness of the area where the non-notch groove is located.

In one example, the end cap body 241 may further include an abutment portion 242, the abutment portion 242 protruding toward a side of the electrode assembly 22 with respect to the end cap body 241 such that the abutment portion 242 can abut a side surface of the current collecting member 23 remote from the electrode assembly 22 when the end cap body 241 is closed. The abutment 242 against the current collecting member 23 can provide structural support for the current collecting member 23 on the one hand to enhance the deformation resistance of the current collecting member 23, and on the other hand, the abutment 242 against the current collecting member 23 can achieve conductive communication of both, thereby conducting the current collected to the current collecting member 23 to the end cap 24, so that the end cap 24 together with the housing 21 serves as the extraction electrode of the first pole piece.

This embodiment allows for both the energy density of the cell 20 and the structural strength of the end cap 24 by properly designing the thickness of the end cap 24 at different locations.

In some embodiments, the thickness C1 of the overlap 243 may be designed to be: 0.2 mm.ltoreq.C1.ltoreq.0.5 mm, the thickness C2 of the end cap body 241 may be designed as: c2 is more than or equal to 0.3mm and less than or equal to 0.7mm.

Through a great deal of experimental analysis by the applicant, when the value range of C1 is 0.2 mm-0.5 mm and the value range of C2 is 0.3 mm-0.7 mm, the energy density of the battery cell 20 and the structural strength of the end cover 24 can be better considered. In some embodiments of the present application, the thickness C1 of the overlap 243, the thickness C2 of the end cap body 241 may be further designed to: c1 is more than or equal to 0.3mm and less than or equal to 0.4mm, C2 is more than or equal to 0.4mm and less than or equal to 0.6mm.

FIG. 13 is an enlarged view of a portion of FIG. 7 at C in another embodiment; fig. 14 is a partial enlarged view of fig. 7 at C in yet another embodiment. In some embodiments, as shown in fig. 13 to 14, the case 21 includes a body part 213 and a welding part 214, the body part 213 surrounding the outside of the electrode assembly 22, the welding part 214 being located at one end of the body part 213 near the opening, and the current collecting member 23 is welded with the welding part 214 to form the first welding part 26. The open end face 212 is located at an end of the welded portion 214 remote from the electrode assembly 22, and the second connecting portion 233 is welded to the welded portion 214 to form the first welded portion 26.

In this example, the main body portion 213 and the welding portion 214 are disposed in this order in the axial direction of the electrode assembly 22, and an end of the welding portion 214 remote from the main body portion 213 surrounds an opening forming the case 21. For the cylindrical housing 21, the main body 213 and the welded portion 214 are both annular. The end of the welded portion 214 remote from the electrode assembly 22 is an open end face 212 defining the opening of the case 21.

By forming the first welded portion 26 after welding and melting the current collecting member 23 with the welded portion 214 near the open end of the case 21, the internal resistance can be reduced to achieve the conductive connection while achieving the sealed connection.

In some embodiments, as shown in fig. 13, an end surface of the second connection portion 233 remote from the first connection portion 232 is lower than the opening end surface 212.

The second connection portion 233 is heated and melted during welding, so that welding deformation to a certain extent occurs, and the end surface of the second connection portion 233 is lower than the opening end surface 212, so that a certain space for accommodating the welding deformation can be provided for welding when the first welding portion 26 is formed, and the influence of the welding deformation on the installation of subsequent components, such as the installation alignment between the end cover 24 and the opening end surface, is relieved.

In some embodiments, as shown in fig. 14, an end surface of the second connection portion 233 remote from the first connection portion 232 is flush with the opening end surface 212.

The fact that the second connection part 233 is flush with the end surface of the welding part 214 means that the end surfaces of the second connection part 233 and the welding part 214 are located in the same plane can increase the abutting length of the second connection part 233 and the welding part 214 of the case 21 along the axial direction X of the electrode assembly 22 as much as possible, so that a sufficient welding space is provided between the second connection part 233 and the welding part 214 to form the first welding part 26, and the welding forming quality of the first welding part 26 can be improved. It is understood that, without affecting the welding, the end surfaces of the second connection portion 233 and the welding portion 214 cannot be completely coplanar due to the manufacturing precision or the butt positioning, and the second connection portion 233 and the welding portion 214 are also within the scope of flush.

In some embodiments, as shown in fig. 6, 13, and 14, the first weld 26 is configured as a penetration weld formed by laser penetrating the second connection 233 and melting at least a portion of the weld 214.

The laser penetrating the second connection part 233 in a direction intersecting the axis of the electrode assembly 22 and at least partially melting the welding part 214 means that the second connection part 233 and the welding part 214 form the first welding part 26 by means of internal welding that is emitted outward from the inside of the battery, and the first welding part 26 is located on the sidewall of the second connection part 233. For example, the laser may be emitted onto the second connection part 233 in a direction perpendicular to the axial direction X of the electrode assembly 22, and the laser breaks down the second connection part 233 and then projects onto the case 21, so that the second connection part 233 is welded to the case 21 to form the first welded part 26.

The laser emission direction is emitted to the outside of the battery when the internal welding mode is adopted for welding, so that the electrode damage caused by the emission of the laser to the electrode assembly during welding is avoided, and the safety of welding operation is improved.

In some embodiments, as shown in fig. 8, the first weld 26 is configured as a butt weld formed by laser irradiation at the location of the butt of the second connection 233 and the weld 214.

The first welded portion 26 may be a butt weld, i.e., a laser is directed to the second connection portion 233 and the welding portion 214 at the aligned position, while melting portions of the second connection portion 233 and the welding portion 214 to form a weld. In one example, the second connection portion 233 is flush with the open end face 212 of the welding portion 214, so that the second connection portion 233 and the welding portion 214 may form the first welding portion 26 at a butt-joint position of the two by butt welding.

The laser has sufficient arrangement space outside the battery during butt welding, which is beneficial to improving the precision of laser welding and further improving the welding quality, and simultaneously, the first welding part 26 is formed by butt welding and positioned on the end surfaces of the second connecting part 233 and the welding part 214, so that the length of the second connecting part 233, which is attached to the welding part 214 along the axial direction of the electrode assembly 22, can be reduced, and the internal space occupying the battery shell is reduced.

Fig. 15 is a partial enlarged view at B in fig. 5 in another embodiment. In some embodiments, referring to fig. 6 and 15, a groove 2421 is provided on a side of the overlap portion 243 facing the current collecting member 23, and the groove 2421 is disposed corresponding to the first welding portion 26.

In one example, the first welding portion 26 formed by butt welding the end surface of the second connecting portion 233 and the opening end surface of the welding portion 214 is a butt welding seam, for example, as shown in fig. 15, the butt welding seam may deteriorate the flatness of the opening end surface 212 and may even protrude from the surface where the opening end surface 212 is located, and the groove 2421 provided corresponding to the first welding portion 26 may avoid the first welding portion 26 when the end cover 24 is assembled, so as to improve the assembly accuracy.

In some embodiments, the inner diameter D2 of the body portion 213 is less than the inner diameter D1 of the weld 214.

The inner diameter of the body portion 213 is smaller than the inner diameter D1 of the welding portion 214 so that the inner surface of the case forms a larger-sized flared space at one end near the opening, thereby providing a larger assembly space for the installation location and welding connection of the current collecting member 23, and making assembly easier.

In some embodiments, as shown in fig. 13 and 14, the junction of the body portion 213 and the welded portion 214 forms a stepped surface against which the current collecting member 23 abuts.

The inner diameters of the main body 213 and the welding portion 214 may be changed abruptly at the connection position, and a right-angle or approximately right-angle stepped surface may be formed, or may be changed gradually, for example, in a chamfer or rounded transition, and the transition portion may also form a stepped surface with gradually changed dimensions.

The inner diameters of the main body 213 and the welding part 214 are different, so that a step surface is formed at the joint of the inner sides of the main body 213 and the welding part, the current collecting member 23 can be positioned through the step surface, more convenient butt joint positioning is realized, and the assembly efficiency is improved.

In some embodiments, as shown in fig. 13, the wall thickness of the body portion 213 is equal to the wall thickness of the weld 214.

When the wall thickness of the main body 213 is equal to the wall thickness of the welding portion 214, the inner diameter D1 of the welding portion 214 being larger than the inner diameter D2 of the main body 213 means that the welding portion 214 is expanded outward with respect to the whole main body 213, that is, the outer diameter of the welding portion 214 is also larger than the outer diameter of the main body 213, so that the strength of the case 21 can be maintained while the stepped portion is formed to better position the current collecting member 23.

In some embodiments, as shown in fig. 14, the outer side of the body portion 213 is coplanar with the outer side of the weld 214.

The fact that the outer side surface of the main body 213 is coplanar with the outer side surface of the welding portion 214 means that the outer side surfaces of the main body 213 and the welding portion 214 are flat surfaces, and the outer diameters of the main body 213 and the welding portion 214 are equal, and when the inner diameter D2 of the main body 213 is smaller than the inner diameter D1 of the welding portion 214, it means that the thickness of the welding portion 214 is smaller than the thickness of the main body 213, and the inner side portion of the welding portion 214 is cut down, so that a stepped surface is formed between the welding portion 214 and the inner side surface of the main body 213.

The outer side surface of the main body 213 is coplanar with the outer side surface of the welding part 214, so that the uniformity of the sizes of the outer surfaces of the battery cells can be maintained, and the combination and assembly of a plurality of battery cells can be facilitated.

In some embodiments, the inner diameter D1 of the weld 214 and the inner diameter D2 of the body portion 213 satisfy: D1-D2 is more than or equal to 0.1mm.

Through a large number of experimental analysis by the applicant, the values of D1 and D2 can be met, D1-D2 is more than or equal to 0.2mm, so that a step surface formed between a welding part and a main body part is provided with a certain width for placing the current collecting member 23, thereby better providing positioning for the installation of the current collecting member 23, improving the installation precision of the current collecting member 23 and improving the assembly efficiency.

In some embodiments, as shown in fig. 14, the current collecting member 23 includes a first material layer 234 and a first welding auxiliary layer 235, the first material layer 234 is different from the first welding auxiliary layer 235 in material, and the first welding auxiliary layer 235 is located on a side surface of the first material layer 234 facing the case 21.

The melting point, laser absorptivity and thermal expansion coefficient of different materials are different, and when the current collecting member 23 and the shell 21 are welded by laser, effective welding marks or cracks can not be formed due to large material difference, and welding quality can be improved by arranging a welding assisting layer on the welded surface.

In some embodiments, as shown in fig. 14, the case 21 includes a second material layer 215 and a second soldering flux layer 216, the second material layer 215 is different from the second soldering flux layer 216 in material, and the second soldering flux layer 216 is located on a side surface of the second material layer 215 facing the current collecting member 23.

The soldering flux layer may be disposed on a side surface of the second material layer 215 of the case 21 facing the current collecting member 23, or may be disposed on a side surface of the first material layer 234 of the current collecting member 23 facing the case 21, or may be disposed on both surfaces of the case 21 and the current collecting member 23 facing each other. Thus, the molding quality of the solder printing can be further improved.

In some embodiments, the material of the first material layer 234 is copper, and the material of the second material layer 215 is carbon steel.

The first material layer 234 of the current collecting member 23 is made of copper with high conductivity, so that current collection can be better realized, and the internal resistance of the battery can be reduced. The second material layer 215 of the housing 21 is carbon steel, which can be used for both structural strength and electrical conductivity.

In some embodiments, the material of the first soldering mask 235 and the material of the second soldering mask 216 are nickel.

The soldering flux layer may be formed by electroplating a plating layer, such as a nickel plating layer, on the surfaces of the current collecting member 23 and the case 21, it being understood that the current collecting member 23 and the case 21 may be entirely plated with the soldering flux layer, or the soldering flux layer may be plated on the surface of the area where the soldering position is located according to the position of the specific soldering connection to facilitate soldering.

In some embodiments, as shown in FIG. 14, the first solder mask 235 has a thickness u1 and the second solder mask 216 has a thickness u2, where 1 um.ltoreq.u1+u2.ltoreq.9um.

In some examples, u1 and u2 may also satisfy 2 μm+.u1+u2+.8μm. In this embodiment, through the thickness of rationally setting up the helping welding layer, can control the weight of end cover and casing when supplementary welding, reduce unnecessary weight loss.

In some embodiments, as shown in fig. 5, the electrode assembly 22 further includes a second tab 221B having a polarity different from that of the first tab 221A; the battery cell further includes an electrode terminal 27, and the electrode terminal 27 is located at an end of the case 21 away from the opening and is electrically connected to the second tab 221B.

The first tab 221A and the second tab 221B are respectively located at different sides of the electrode assembly 22, the first tab 221A is electrically connected with the case 21 through the current collecting member 23, the second tab 221B is electrically connected with the electrode terminal 27, and the electrode terminal 27 extends out of the case 21 and is insulated from the case 21.

Embodiments of the second aspect of the present application provide a battery 100 including the battery cell 20 in the above embodiment.

An embodiment of a third aspect of the present application provides an electric device comprising a battery 100 as in the above embodiment, the battery 100 being for providing electric energy.

The structure of the battery cell 20 of the present application will be described below by way of two specific embodiments taking a cylindrical battery cell 20 as an example.

Fig. 3 to 6 show a battery cell 20, the battery cell 20 including a case 21, an electrode assembly 22, a current collecting member 23, and an end cap 24. Wherein the case 21 has an opening and an opening end face 212 surrounding the opening, the case 21 has an end wall 211 facing the opening, and the electrode terminal 27 is mounted on the end wall 211. The electrode assembly 22 is disposed in the case 21, the electrode assembly 22 has a cylindrical shape, the electrode assembly 22 includes a first tab 221A and a second tab 221B, the first tab 221A and the second tab 221B are located at different sides of the electrode assembly 22, the first tab 221A is electrically connected with the current collecting member 23, and the second tab 221B is electrically connected with the electrode terminal 27.

The case 21 includes a main body portion 213 and a welding portion 214, the main body portion 213 surrounding the periphery of the electrode assembly 22, the welding portion 214 being located at a section of the main body portion 213 close to the opening, and an end surface of the welding portion 214 remote from the electrode assembly 22 being an opening end surface 212 defining the opening of the case 21.

The current collecting member 23 is disposed in the case 21, the current collecting member 23 includes a first connection portion 232 and a second connection portion 233, the second connection portion 233 is connected to an outer edge of the first connection portion 232 and has a circular ring structure, a plurality of reinforcing ribs 231 are disposed on the first connection portion 232, the reinforcing ribs 231 are punching grooves protruding from a surface of the first connection portion 232 facing the electrode assembly 22, a bottom wall of each punching groove is welded with the first tab 221A to form a second welding portion 25, and the second connection portion 233 is welded with an inner side of the welding portion 214 of the case 21 to form a first welding portion 26. Among them, the second welding parts 25 are formed in 3, 4, or 6, etc., and the plurality of second welding parts 25 are uniformly distributed around the central axis of the electrode assembly 22. Similarly, the second welding parts 26 are also formed in plurality, the plurality of second welding parts 26 are uniformly distributed around the central axis of the electrode assembly 22, and the sum of the lengths of all the first welding parts 26 along the circumferential direction of the case 21 is a first length L1, the first length L1 and a second length L2 satisfy: l1 is more than or equal to 0.5 xL 2. The thickness of the second connection part 233 in the direction perpendicular to the axial direction of the electrode assembly 22 is t1, and the height of the second connection part 233 in the axial direction of the electrode assembly 22 is h0, t1 and h0 satisfy: h0/t1 is more than or equal to 2 and less than or equal to 6.

The junction of the first and second connection parts 232 and 233 may be formed with a rounded transition such that the junction is formed as a rounded corner. The outer diameter of the annular second connection part 233 is larger than the inner diameter of the case 21 such that the second connection part 233 is interference-fitted with the cavity of the case 21, the second connection part 233 including the boss 2331 and the notch 2332 located between the adjacent boss 2331, the height dimension h1 of the notch 2332 along the axial direction X of the electrode assembly 22 being smaller than or equal to the height h0 of the boss 2331.

The end cap 24 may be provided with a pressure release mechanism, such as a score groove, and the end cap 24 may include an end cap body 241, an abutting portion 242 surrounding the end cap body 241, and a lap portion 243, wherein the abutting portion 242 abuts against a surface of the first connecting portion 232 facing away from the electrode assembly 22, a side surface of the end cap body 241 facing away from the electrode assembly 22 is coplanar with a side surface of the lap portion 243 facing away from the case 21, the lap portion 243 is connected with the open end face 212, and a thickness C1 of the lap portion 243 is smaller than a thickness C2 of the end cap body 241 along an axial direction X of the electrode assembly 22. The overlap 243 is provided with a groove 2421 provided corresponding to the first welded portion 26 on a side facing the case 21.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the embodiments, and are intended to be included within the scope of the claims and description. 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 (40)

1. A battery cell, comprising:

an electrode assembly including a first tab;

a case for accommodating the electrode assembly;

the current collecting member is accommodated in the shell, the current collecting member is electrically connected with the first tab, and the current collecting member is welded with the shell.

2. The battery cell according to claim 1, wherein the current collecting member comprises:

the first connecting part is used for being electrically connected with the first tab;

and the second connecting part is connected with the first connecting part, is arranged along the edge of the first connecting part and protrudes in a direction away from the electrode assembly, and is welded with the shell.

3. The battery cell according to claim 2, wherein the thickness of the second connection part in a direction perpendicular to the axial direction of the electrode assembly is t1, and the height of the second connection part in the axial direction of the electrode assembly is h0, and satisfies: h0/t1 is more than or equal to 2 and less than or equal to 6.

4. The battery cell according to claim 2, wherein a thickness of the second connection part in a direction perpendicular to an axial direction of the electrode assembly is t1,0.1mm ∈t1 ∈0.5mm.

5. The battery cell of claim 2, wherein an outer side of the second connection portion is an interference fit with an inner side of the housing.

6. The battery cell according to claim 5, wherein the second connection portion includes a plurality of protruding portions disposed at intervals along the inner wall circumference of the case, and a notch portion between two adjacent protruding portions; the plurality of protruding portions are welded with the housing to form a plurality of first welding portions.

7. The battery cell of claim 6, wherein the plurality of protrusions are evenly spaced around a central axis of the electrode assembly.

8. The battery cell according to claim 6, wherein the height of the protruding portion of the second connection portion in the axial direction of the electrode assembly is h0, and the height of the notch portion in the axial direction of the electrode assembly is h1, h1 is equal to or less than h0.

9. The battery cell according to any one of claims 2 to 8, wherein a projected length of a first welded portion formed by welding the second connection portion with the case in an axial direction of the electrode assembly is a first length L1, a projected perimeter of an inner side surface of the case in the axial direction of the electrode assembly is a second length L2, and the first length L1 and the second length L2 satisfy: l1 is more than or equal to 0.5 xL 2.

10. The battery cell according to any one of claims 2 to 8, wherein the first connection portion is welded with the first tab.

11. The battery cell according to claim 10, wherein the first connection part includes a first side facing the electrode assembly and a second side facing away from the electrode assembly, at least one of the first side and the second side being provided with a reinforcing rib for reinforcing the first connection part.

12. The battery cell according to claim 11, wherein at least one of the reinforcing ribs on the first side surface is disposed in correspondence with the first tab to form a second welded portion.

13. The battery cell according to claim 12, wherein the reinforcing rib for forming the second welded portion is a punched groove protruding toward the electrode assembly, and a side of the punched groove facing away from the electrode assembly is recessed in the second side.

14. The battery cell of claim 13, wherein the number of stamped grooves is greater than or equal to three.

15. The battery cell according to claim 14, wherein a plurality of the punched grooves are uniformly spaced apart in a circumferential direction of a center of the first connection portion.

16. The battery cell of claim 13, wherein the stamped groove is a plurality of radially extending spoke-like patterns or a plurality of crescent-like patterns.

17. The battery cell according to any one of claims 2 to 8, wherein a connection of the second connection portion and the first connection portion is formed with a chamfer or a radius.

18. The battery cell according to any one of claims 2 to 8, wherein a thickness of the first connection part in an axial direction of the electrode assembly is t2, and 0.1mm ∈t2 ∈0.5mm.

19. The battery cell according to any one of claims 2 to 8, wherein the housing includes an open end face forming an opening, the battery cell further comprising an end cap including an end cap body and a lap joint portion surrounding an outer edge of the end cap body, the lap joint portion being connected with the open end face to cover the opening.

20. The battery cell according to claim 19, wherein a thickness C1 of the overlap portion and a thickness C2 of the end cap body satisfy c1.ltoreq.c2 in an axial direction of the electrode assembly.

21. The battery cell of claim 20, wherein the overlap has a thickness C1 of 0.2mm C1 0.5mm and the end cap body has a thickness C2 of 0.3mm C2 0.7mm.

22. The battery cell according to claim 19, wherein the case includes a body portion and a welding portion connected, the body portion surrounding an outer side of the electrode assembly, the welding portion being located at an end of the body portion near an opening, the opening end face being located at an end of the welding portion remote from the electrode assembly, the second connecting portion being welded with the welding portion to form a first welded portion.

23. The battery cell of claim 22, wherein an end surface of the second connection portion remote from the first connection portion is flush with the open end surface.

24. The battery cell of claim 22, wherein an end surface of the second connection portion remote from the first connection portion is lower than the open end surface.

25. The battery cell of claim 22, wherein the first weld is configured as a penetration weld formed by laser penetration of the second connection and melting at least a portion of the weld.

26. The battery cell of claim 22, wherein the first weld is configured as a butt weld formed by laser irradiation at a butt location of the second connection and the weld.

27. The battery cell according to claim 26, wherein the overlap portion is provided with a groove on a side facing the current collecting member, the groove being provided corresponding to the first welding portion.

28. The battery cell of claim 22, wherein an inner diameter of the body portion is less than an inner diameter of the weld.

29. The battery cell of claim 28, wherein a junction of the body portion and the weld forms a stepped surface against which the current collecting member abuts.

30. The battery cell of claim 29, wherein a wall thickness of the body portion is equal to a wall thickness of the weld.

31. The battery cell of claim 29, wherein an outer side of the body portion is coplanar with an outer side of the weld.

32. The battery cell according to claim 28, wherein an inner diameter D1 of the welded portion and an inner diameter D2 of the main body portion in a direction perpendicular to an axial direction of the electrode assembly satisfy: D1-D2 is more than or equal to 0.1mm.

33. The battery cell according to any one of claims 1 to 8, wherein the current collecting member includes a first material layer and a first welding auxiliary layer, the first material layer is different from the first welding auxiliary layer in material, and the first welding auxiliary layer is located at a side surface of the first material layer facing the case.

34. The battery cell of claim 33, wherein the housing comprises a second material layer and a second weld assist layer, the second material layer being of a different material than the second weld assist layer, the second weld assist layer being located on a side surface of the second material layer facing the current collecting member.

35. The battery cell of claim 34, wherein the first material layer is copper and the second material layer is carbon steel.

36. The battery cell of claim 34, wherein the first weld overlay and the second weld overlay are both nickel.

37. The battery cell of claim 34, wherein the first weld overlay has a thickness u1 and the second weld overlay has a thickness u2, wherein 1um +.u1+u2 +.9um.

38. The battery cell according to any one of claims 1 to 8, wherein the electrode assembly further comprises a second tab having a polarity different from the polarity of the first tab; the housing includes an opening, and wherein,

the battery cell also comprises an electrode terminal, wherein the electrode terminal is positioned at one end of the shell far away from the opening and is electrically connected with the second lug.

39. A battery comprising a cell according to any one of claims 1 to 38.

40. An electrical device comprising a battery according to claim 39, wherein the battery is configured to provide electrical energy.

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