CN216085065U - Battery cell, battery and power consumption device - Google Patents

Abstract

The embodiment of the application provides a battery monomer, a battery and a power consumption device. The battery cell of the embodiment of the application includes: a housing having an opening; an electrode assembly housed in the case; and an end cap for covering the opening, the end cap including a cap body and a protrusion surrounding an outside of the cap body, the protrusion protruding from an inner surface of the cap body in a direction facing the electrode assembly, and at least a portion of the protrusion being located within the case and adapted to fit with the case. The end cap is formed with a concave portion at a position corresponding to the convex portion, the concave portion being depressed from the outer surface of the cap body in a direction facing the electrode assembly and serving to release stress during the protrusion extending into the case. The battery assembling method and the battery assembling device can improve the assembling efficiency of the battery monomer and enhance the safety of the battery monomer.

Description

Battery cell, battery and power consumption device

Technical Field

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

Background

The battery cell is widely used in electronic devices such as a mobile phone, a notebook computer, a battery car, an electric airplane, an electric ship, an electric toy car, an electric toy ship, an electric toy airplane, an electric tool, and the like. The battery monomer can comprise a cadmium-nickel battery monomer, a hydrogen-nickel battery monomer, a lithium ion battery monomer, a secondary alkaline zinc-manganese battery monomer and the like.

In the development of battery technology, how to improve the assembly efficiency of battery cells is a research direction in battery technology.

Disclosure of Invention

The application provides a battery monomer, battery and power consumption device, it can improve the free assembly efficiency of battery, strengthens the free security of battery.

In a first aspect, an embodiment of the present application provides a battery cell, including:

a housing having an opening;

an electrode assembly housed in the case; and

an end cap for covering the opening, the end cap including a cap body and a protrusion surrounding an outer side of the cap body, the protrusion protruding from an inner surface of the cap body in a direction facing the electrode assembly, and at least a portion of the protrusion being located within the case and for fitting with the case;

and the end cover is provided with a concave part corresponding to the convex part, and the concave part is sunken from the outer surface of the cover body along the direction facing the electrode assembly and is used for releasing stress in the process that the convex part extends into the shell.

In the above scheme, the convex part can stretch into in the casing when assembling end cover and casing to with the position of casing cooperation in order to inject the end cover, thereby reduce the degree of difficulty of location casing and end cover, improve the free assembly efficiency of battery. The shell can limit the position of the end cover through the convex part, so that the offset and the dislocation between the end cover and the shell can be reduced in the process of connecting the end cover and the shell, and the sealing performance is improved. The concave part can reduce the strength of the convex part, so that when the convex part and the shell are pressed against each other, the convex part can release stress through deformation, the pressing force and the friction force between the convex part and the shell are reduced, generated particles are reduced, the risk of deformation of the shell is reduced, and the safety performance of the battery monomer is improved.

In some embodiments, a bottom surface of the recess is entirely closer to the electrode assembly than an inner surface of the cap body in a thickness direction of the end cap.

Above-mentioned scheme can guarantee the sunken degree of depth of first concave part to improve the degree that the convex part protrudes the internal surface of lid body, can improve the cooperation effect between convex part and the casing like this, improve the elasticity of convex part, with extrusion force and the frictional force between reduction convex part and the casing, reduce the granule that produces, reduce the risk that the casing warp, improve the free security performance of battery.

In some embodiments, the side wall of the case extends in the thickness direction of the end cap and is disposed around the outer periphery of the electrode assembly, the inner wall surface of the side wall and the outer peripheral surface of the convex portion are both parallel to the thickness direction, and are disposed opposite to each other.

In the above solution, the inner wall surface of the side wall and the outer peripheral surface of the convex portion are arranged in parallel, so that when the inner wall surface of the side wall and the outer peripheral surface of the convex portion contact and press each other, the stress between the inner wall surface of the side wall and the outer peripheral surface of the convex portion is relatively uniform, thereby reducing stress concentration and reducing deformation of the housing and the convex portion.

In some embodiments, the side wall of the housing and the protrusion are interference fit such that an inner wall surface of the side wall and an outer peripheral surface of the protrusion are abutted.

In the above scheme, the interference fit can increase the connection strength between the shell and the end cover and improve the sealing performance. This scheme has reduced the intensity of convex part through setting up the concave part to the in-process that stretches into the casing at the convex part has reduced the effort between convex part and the casing, like this, even casing and convex part interference fit, also can reduce the granule that produces, reduce the risk that the casing warp, improve the free security performance of battery.

In some embodiments, the inner wall surface of the sidewall is welded to the outer peripheral surface of the projection and forms a first weld. In the thickness direction, the first welding part does not exceed the outer surface of the cap body in a direction away from the electrode assembly.

In the above scheme, the cover body can be used as a bearing structure of the battery cell. After the battery cell is mounted to the electric device, an external support structure may support the battery cell through the cover body. This scheme makes first weld part not surpass the surface of lid body along the direction that deviates from electrode subassembly to reduce the effort between outside bearing structure and the first weld part, reduce the cracked risk of first weld part, guarantee joint strength and sealing performance between casing and the end cover.

In some embodiments, the sidewall includes a first outer end face surrounding the opening, the first outer end face being connected to an inner wall surface of the sidewall. In the thickness direction, the convex portion has a second outer end surface at an end facing away from the electrode assembly, the second outer end surface is connected to the outer peripheral surface of the convex portion, the first outer end surface and the second outer end surface are flush, and the first outer end surface and the second outer end surface are closer to the electrode assembly than the outer surface of the cap body.

Above-mentioned scheme makes first outer terminal surface and second outer terminal surface compare in the surface of lid body and is closer to electrode assembly, like this, even first welding part protrusion in first outer terminal surface and second outer terminal surface, also can make first welding part along the direction that deviates from electrode assembly not surpass the surface of lid body to reduce the effort that first welding part received, reduce the cracked risk of first welding part, guarantee joint strength and sealing performance between casing and the end cover.

In some embodiments, the housing further includes a flange portion connected to the side wall and bent toward the cover body with respect to the side wall to cover the first welding portion.

In the above scheme, first welding part can be protected to turn-ups portion, reduces the risk that first welding part is corroded, is destroyed, guarantees joint strength and sealing performance between casing and the end cover.

In some embodiments, the end cap further includes an extension portion protruding from an outer circumferential surface of the protrusion and surrounding an outer side of the protrusion, and an inner surface of the extension portion is welded to the first outer end surface of the sidewall surrounding the opening, so that the housing and the end cap are integrally connected.

In the above scheme, when assembling the end cover and the shell, the first outer end face can play a limiting role in the thickness direction of the end cover, the risk that the end cover is excessively inserted into the shell is reduced, and the assembling efficiency is improved.

In some embodiments, the protrusion and the housing are clearance fit to form a gap between an outer peripheral surface of the protrusion and an inner wall surface of the sidewall.

In the above scheme, clearance fit can enough guarantee that the casing is spacing to the convex part, can also stretch into the in-process of casing at the convex part and reduce the effort between convex part and the casing, reduces the frictional risk of convex part and casing, reduces the granule that produces and reduces the deformation of casing, improves the free security performance of battery.

In some embodiments, a size of a gap between an outer circumferential surface of the protrusion and an inner wall surface of the sidewall in a direction from the electrode assembly toward the sidewall is 0.02mm to 0.5mm.

In the above aspect, the smaller the size of the gap, the higher the risk of friction between the outer peripheral surface of the projection and the inner wall surface of the side wall, and the higher the risk of particle generation; the larger the size of the gap, the larger the range over which the projection can move after it has been inserted into the housing, and the higher the risk of poor welding of the extension and the housing. The inventors set the size of the gap to 0.02mm-0.5mm to balance the risk and improve safety.

In some embodiments, the inner surface of the extension portion is provided with an avoidance groove surrounding the outside of the projection portion, and a groove wall surface of the avoidance groove is used for connecting the inner surface of the extension portion and the outer peripheral surface of the projection portion.

In the above scheme, when the convex part is formed, the connecting part of the convex part and the extending part is provided with the fillet so as to reduce stress concentration. In the scheme, the avoiding groove is formed in the extending part, and the part of the extending part, which is opposite to the avoiding groove, is connected to the convex part; the avoiding groove is arranged in a concave manner and can provide flowing space for materials when the convex part is formed, so that a round angle is formed at the part of the extending part, which is opposite to the avoiding groove, and the surface of the round angle is a part of the groove wall surface of the avoiding groove; the groove wall surface is recessed relative to the inner surface of the extension portion, so that the embodiment can ensure that the first outer end surface is smoothly abutted against the inner surface of the extension portion, and the fillet is prevented from interfering with the first outer end surface.

In some embodiments, the outer surface of the extension is flush with the outer surface of the cap body.

In the above scheme, the external support structure can support the battery cell through the extension part and the cover body, so that the area of the bearing part of the end cover can be increased, and the stability of the battery cell is improved.

In some embodiments, the extension does not extend beyond the outer wall surface of the sidewall in a direction from the electrode assembly toward the sidewall.

According to the scheme, the extension part can be prevented from increasing the maximum size of the battery monomer, and the energy density of the battery monomer is ensured. In addition, the end cap is thin, and if the extension portion exceeds the outer wall surface of the side wall, other external components may be scratched.

In some embodiments, the outer wall surface of the sidewall extends 0.02mm to 0.5mm beyond the extension in a direction from the electrode assembly toward the sidewall.

In the above scheme, the smaller the dimension of the outer wall surface of the side wall exceeding the extension part is, the higher the risk that a second welding part formed by welding the side wall and the extension part protrudes out of the outer wall surface of the side wall is; the larger the size of the outer wall surface of the side wall exceeding the extension part is, the smaller the connection area between the extension part and the side wall is, and the lower the connection strength between the extension part and the side wall is. The inventor sets the size of the outer wall surface of the side wall exceeding the extension part to be 0.02mm-0.5mm so as to reduce the risk that the second welding part protrudes out of the outer wall surface of the side wall as much as possible on the premise of ensuring the connection strength.

In some embodiments, the dimension of the outer circumferential surface of the extended portion projecting convex portion in a direction from the electrode assembly toward the side wall is smaller than the wall thickness of the side wall.

In the above aspect, when the outer peripheral surface of the convex portion abuts against the inner wall surface of the side wall, since the wall thickness of the side wall is larger than the size of the extending portion protruding beyond the outer peripheral surface of the convex portion, the outer wall surface of the side wall exceeds the extending portion in the direction in which the electrode assembly is directed toward the side wall.

In some embodiments, the protrusion further includes a guide surface facing the side wall, the guide surface being connected to an end of an outer circumferential surface of the protrusion near the electrode assembly, and the guide surface being inclined in a direction away from an inner wall surface of the side wall compared to the outer circumferential surface of the protrusion to guide the protrusion to protrude into the case.

In the scheme, the inclined guide surface is arranged on the convex part, so that the convex part can be guided to be inserted into the shell when the end cover and the shell are assembled, the assembly process is simplified, and the assembly efficiency is improved.

In some embodiments, the protrusion abuts against a first tab of the electrode assembly to support the first tab.

In the above scheme, the convex part can support the first tab, so that the shaking amplitude of the electrode assembly when the battery monomer shakes is reduced, and the stability of the electrode assembly is improved.

In some embodiments, the tab is welded to the first tab to electrically connect the first tab to the end cap.

In the scheme, the convex part and the first electrode lug are directly welded, and other adapting components are not needed, so that the structure of the battery cell is simplified. This scheme reduces the thickness of convex part through setting up the concave part, can reduce convex part and the required welding power of first utmost point ear welding like this, reduces the heat production, reduces the risk that other components are burnt.

In some embodiments, the first tab of the electrode assembly is electrically connected to the case through the end cap.

In the above-mentioned solution, the case is connected to the first tab of the electrode assembly through the end cap, so that the potential of the case is substantially the same as the potential of the first tab, and thus, the case itself can serve as the output electrode of the battery cell, thereby omitting a conventional electrode terminal and simplifying the structure of the battery cell. When a plurality of battery monomers are assembled into a group, the shell can be electrically connected with the confluence component, so that the flow area can be increased, and the structural design of the confluence component can be more flexible.

In some embodiments, the case includes a side wall extending in a thickness direction of the end cap and disposed around a periphery of the electrode assembly, and a bottom wall connected to one end of the side wall and located on a side of the electrode assembly facing away from the end cap, the bottom wall being provided with an electrode lead-out hole. The electrode assembly is provided with a second tab at an end facing the bottom wall, the first tab and the second tab being of opposite polarity. The battery unit also comprises an electrode terminal arranged in the electrode leading-out hole, and the electrode terminal is electrically connected with the second lug.

In the above scheme, the bottom wall and the electrode terminal can be used as two output electrodes of the battery cell, so that the structure of the battery cell can be simplified, and the overcurrent capacity of the battery cell can be ensured. The bottom wall and the electrode terminal are located at the same end of the battery cell, so that the bus bar component can be assembled to the same side of the battery cell, the assembly process can be simplified, and the assembly efficiency of a plurality of battery cells is improved.

In some embodiments, the bottom wall and the side wall are an integrally formed structure.

The scheme can omit the connecting process of the bottom wall and the side wall and reduce the resistance between the bottom wall and the side wall.

In some embodiments, the first tab is a negative tab, and the base material of the casing is steel.

In the above scheme, the casing is electrically connected with the negative electrode tab, that is, the casing is in a low potential state. The steel shell is not easily corroded by electrolyte in a low potential state, so that the safety risk is reduced.

In some embodiments, the battery cell is a cylindrical battery cell.

In a second aspect, an embodiment of the present application provides a battery, including a plurality of battery cells according to any of the embodiments of the first aspect.

In a third aspect, an embodiment of the present application provides an electric device, including the battery of the second aspect, where the battery is used to provide electric energy.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for a person skilled in the art to obtain other drawings based on the drawings without any creative effort.

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

fig. 2 is an exploded schematic view of a battery provided in accordance with some embodiments of the present application;

fig. 3 is an exploded schematic view of the battery module shown in fig. 2;

fig. 4 is an exploded schematic view of a battery cell provided in some embodiments of the present application;

fig. 5 is a schematic cross-sectional view of a battery cell provided in some embodiments of the present application;

fig. 6 is an enlarged schematic view of the battery cell shown in fig. 5 at a circle frame a;

fig. 7 is a schematic cross-sectional view of a battery cell provided in accordance with other embodiments of the present application;

fig. 8 is a schematic cross-sectional view of a battery cell provided in accordance with further embodiments of the present application;

fig. 9 is an enlarged schematic view of the battery cell shown in fig. 8 at a circle frame B;

FIG. 10 is an enlarged schematic view of FIG. 9 at block C;

fig. 11 is a schematic flow chart of a method for manufacturing a battery cell according to some embodiments of the present disclosure;

fig. 12 is a schematic block diagram of a system for manufacturing a battery cell provided in some embodiments of the present application.

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

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

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

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase 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.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "attached" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as the case may be.

The term "and/or" in this application is only one kind of association relationship describing the associated object, and means that there may be three kinds of relationships, for example, a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" in this application generally indicates that the former and latter related objects are in an "or" relationship.

In the embodiments of the present application, like reference numerals denote like parts, and a detailed description of the same parts is omitted in different embodiments for the sake of brevity. It should be understood that the thickness, length, width and other dimensions of the various components in the embodiments of the present application and the overall thickness, length, width and other dimensions of the integrated device shown in the drawings are only exemplary and should not constitute any limitation to the present application.

The appearances of "a plurality" in this application are intended to mean more than two (including two).

In this application, the battery cell may include a lithium ion secondary battery cell, a lithium ion primary battery cell, a lithium sulfur battery cell, a sodium lithium ion battery cell, a sodium ion battery cell, or a magnesium ion battery cell, and the embodiment of the present application is not limited thereto. The battery cell may be a cylinder, a flat body, a rectangular parallelepiped, or other shapes, which is not limited in the embodiments of the present application.

Reference to a battery in embodiments of the present application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in the present application may include a battery module or a battery pack, etc. Batteries generally include a case for enclosing one or more battery cells. The box can avoid liquid or other foreign matters to influence the charging or discharging of battery monomer.

The battery cell comprises an electrode assembly and electrolyte, wherein the electrode assembly comprises a positive pole piece, a negative pole piece and a separator. The battery cell mainly depends on metal ions to move between the positive pole piece and the negative pole piece to work. The positive pole piece comprises a positive pole current collector and a positive pole active substance layer, and the positive pole active substance layer is coated on the surface of the positive pole current collector; the positive current collector comprises a positive current collecting part and a positive electrode lug connected to the positive current collecting part, wherein the positive current collecting part is coated with a positive active substance layer, and the positive electrode lug is not coated with the positive active substance layer. Taking a lithium ion battery as an example, the material of the positive electrode current collector may be aluminum, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, or the like. The negative pole piece comprises a negative pole current collector and a negative pole active substance layer, and the negative pole active substance layer is coated on the surface of the negative pole current collector; the negative current collector comprises a negative current collecting part and a negative electrode lug connected to the negative current collecting part, wherein the negative current collecting part is coated with a negative active material layer, and the negative electrode lug is not coated with the negative active material layer. The material of the negative electrode current collector may be copper, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material may be carbon, silicon, or the like. The material of the spacer may be PP (polypropylene), PE (polyethylene), or the like.

The battery cell further includes a case having an opening and receiving the electrode assembly, and an end cap, through which the electrode assembly may be fitted into the case. The end cover is used for covering the opening of the shell to realize sealing.

In the related art, when the end cap and the housing are assembled, the end cap is usually pressed against the open end of the housing, and then the end cap and the housing are connected by welding or the like. However, the inventor found that the housing and the end cap cannot limit each other in the process of pressing the end cap against the housing, which increases the difficulty of positioning the housing and the end cap by the device and reduces the assembly efficiency of the battery cell. In addition, in the process of connecting the end cover and the shell, the end cover and the shell are easy to deviate and misplace, and the sealing performance is affected.

The inventors have found that it is possible to attempt to provide a protrusion on the end cap which can be inserted into the housing when the end cap and housing are assembled and which cooperates with the housing to define the position of the end cap. The convex part can reduce the difficulty of positioning the shell and the end cover, improve the assembly efficiency of the battery monomer, reduce the offset and dislocation between the end cover and the shell in the process of connecting the end cover and the shell, and improve the sealing performance.

However, the inventors have further found that the protrusions may press the inner surface of the case during insertion into the case, the protrusions and the case rub against each other and form particles, which fall into the electrode assembly and may conduct the positive and negative electrode sheets, thereby causing a safety problem. In addition, if the pressure between the protrusions and the case is excessively high, the case may be deformed, affecting the appearance of the case and the sealability of the battery cell.

In view of this, the embodiments of the present application provide a solution, in which a first concave portion is formed on the end cover at a position corresponding to the convex portion, so as to release stress during the process of the convex portion extending into the housing. The first concave part can reduce the strength of the convex part, so that when the convex part presses the inner surface of the shell, the convex part can release stress through deformation, the pressing force and the friction force between the convex part and the shell are reduced, generated particles are reduced, the risk of deformation of the shell is reduced, and the safety performance of the battery cell is improved.

The technical scheme described in the embodiment of the application is suitable for the battery and the electric device using the battery.

The electric device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool and the like. The vehicle can be a fuel oil vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended vehicle and the like; spacecraft include aircraft, rockets, space shuttles, spacecraft, and the like; electric toys include stationary or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric airplane toys, and the like; the electric power tools include metal cutting electric power tools, grinding electric power tools, assembly electric power tools, and electric power tools for railways, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, electric impact drills, concrete vibrators, and electric planers. The embodiment of the present application does not specifically limit the above power utilization device.

For convenience of explanation, the following embodiments will be described with an electric device as an example of a vehicle.

Fig. 1 is a schematic structural diagram of a vehicle according to some embodiments of the present application.

As shown in fig. 1, a battery 2 is provided inside a vehicle 1, and the battery 2 may be provided at the bottom, head, or tail of the vehicle 1. The battery 2 may be used for power supply of the vehicle 1, and for example, the battery 2 may serve as an operation power source of the vehicle 1.

The vehicle 1 may further comprise a controller 3 and a motor 4, the controller 3 being adapted to control the battery 2 to power the motor 4, e.g. for start-up, navigation and operational power demands while driving of the vehicle 1.

In some embodiments of the present application, the battery 2 may be used not only as an operating power source of the vehicle 1, but also as a driving power source of the vehicle 1, instead of or in part of fuel or natural gas, to provide driving power for the vehicle 1.

Fig. 2 is an exploded schematic view of a battery provided in some embodiments of the present application.

As shown in fig. 2, the battery 2 includes a case 5 and a battery cell (not shown in fig. 2) accommodated in the case 5.

The case 5 is used for accommodating the battery cells, and the case 5 may have various structures. In some embodiments, the case 5 may include a first case portion 5a and a second case portion 5b, the first case portion 5a and the second case portion 5b cover each other, and the first case portion 5a and the second case portion 5b together define a receiving space 5c for receiving the battery cell. The second casing part 5b may be a hollow structure with one open end, the first casing part 5a is a plate-shaped structure, and the first casing part 5a covers the open side of the second casing part 5b to form a casing 5 with a containing space 5 c; the first casing portion 5a and the second casing portion 5b may be hollow structures each having one side opened, and the opening side of the first casing portion 5a may be covered with the opening side of the second casing portion 5b to form the casing 5 having the accommodating space 5c. Of course, the first casing portion 5a and the second casing portion 5b may be various shapes, such as a cylinder, a rectangular parallelepiped, or the like.

In order to improve the sealing property after the first casing portion 5a and the second casing portion 5b are connected, a sealing member, such as a sealant or a gasket, may be provided between the first casing portion 5a and the second casing portion 5 b.

Assuming that the first box portion 5a covers the top of the second box portion 5b, the first box portion 5a may also be referred to as an upper box cover, and the second box portion 5b may also be referred to as a lower box cover.

In the battery 2, one or more battery cells may be provided. If the number of the battery monomers is multiple, the multiple battery monomers can be connected in series or in parallel or in series-parallel, and the series-parallel refers to that the multiple battery monomers are connected in series or in parallel. The plurality of battery monomers can be directly connected in series or in parallel or in series-parallel, and the whole formed by the plurality of battery monomers is accommodated in the box body 5; of course, a plurality of battery cells may be connected in series, in parallel, or in series-parallel to form the battery module 6, and a plurality of battery modules 6 may be connected in series, in parallel, or in series-parallel to form a whole, and may be accommodated in the box 5.

Fig. 3 is an exploded view of the battery module shown in fig. 2.

In some embodiments, as shown in fig. 3, the battery cell 7 is multiple, and the multiple battery cells 7 are connected in series or in parallel or in series-parallel to form the battery module 6. A plurality of battery modules 6 are connected in series or in parallel or in series-parallel to form a whole and are accommodated in the case.

The plurality of battery cells 7 in the battery module 6 may be electrically connected to each other through a bus member, so as to realize parallel connection, series connection, or parallel connection of the plurality of battery cells 7 in the battery module 6.

Fig. 4 is an exploded schematic view of a battery cell provided in some embodiments of the present application; fig. 5 is a schematic cross-sectional view of a battery cell provided in some embodiments of the present application; fig. 6 is an enlarged schematic view of the battery cell shown in fig. 5 at a circle frame a.

As shown in fig. 4 to 6, the battery cell 7 of the embodiment of the present application includes: a housing 20 having an opening 21; an electrode assembly 10 housed in the case 20; and an end cap 30 for covering the opening 21, the end cap 30 including a cap body 31 and a protrusion 32 surrounding an outer side of the cap body 31, the protrusion 32 protruding from an inner surface 311 of the cap body in a direction facing the electrode assembly 10, and at least a portion of the protrusion 32 being located within the case 20 and for fitting with the case 20. The end cap 30 is formed with a recess 33 at a position corresponding to the protrusion 32, and the recess 33 is recessed from the outer surface 312 of the cap body in a direction facing the electrode assembly 10 and serves to release stress during the protrusion 32 protrudes into the case 20.

The electrode assembly 10 includes a first pole piece, a second pole piece, and a separator for separating the first pole piece and the second pole piece. The first and second pole pieces have opposite polarities, that is, one of the first and second pole pieces is a positive pole piece, and the other of the first and second pole pieces is a negative pole piece.

Optionally, the first pole piece, the second pole piece and the spacer are all in a belt-shaped structure, and the first pole piece, the second pole piece and the spacer are wound into a whole and form a winding structure. The coiled structure may be a cylindrical structure, a flat structure, or other shaped structure.

The case 20 has a hollow structure with one side open, and the end cap 30 covers the opening of the case 20 and is hermetically connected to form a receiving cavity for receiving the electrode assembly 10 and the electrolyte.

The case 20 has a hollow structure, and a space for accommodating the electrode assembly 10 is formed inside thereof. The housing 20 may be in various shapes, such as a cylinder, a rectangular parallelepiped, or the like. The shape of the case 20 may be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is of a cylindrical structure, it may be optionally a cylindrical case; if the electrode assembly 10 has a rectangular parallelepiped structure, a rectangular parallelepiped case may be used.

The housing 20 may be positively charged, negatively charged, or uncharged. When the case 20 needs to be charged, the case 20 may be directly connected to the pole pieces of the electrode assembly 10, or may be electrically connected to the pole pieces through other conductive members.

Alternatively, the end cap 30 and the housing 20 may be connected by welding, so that the end cap 30 and the housing 20 may have substantially the same potential. Illustratively, when positive charging of the housing 20 is desired, the end cap 30 may be utilized to electrically connect the housing 20 to a positive polarity pole piece; when housing 20 needs to be negatively charged, end cap 30 can be used to electrically connect housing 20 to the pole piece of negative polarity. Of course, the housing 20 may be connected to the pole piece through other conductive structures, which is not limited in this embodiment.

The end cap 30 may be electrically connected to the electrode assembly 10, or may be disposed to be insulated from the electrode assembly 10. Optionally, end cap 30 is electrically connected to the first pole piece. Of course, the end cap 30 may be electrically connected to the first pole piece directly or through other components.

The housing 20 and the end cap 30 may be made of the same material or may be made of different materials.

The cap body 31 is a plate-shaped structure having inner and outer surfaces oppositely disposed in the thickness direction Z, and the inner surface 311 of the cap body faces the electrode assembly 10. Optionally, the cover body 31 is a flat plate, and the inner surface 311 of the cover body and the outer surface 312 of the cover body are both planar and arranged in parallel.

The projection 32 is an annular structure that surrounds the outside of the cap body 31.

The protrusions 32 protrude in a direction facing the electrode assembly 10 with respect to the inner surface 311 of the cap body such that at least portions of the protrusions 32 protrude from the inner surface 311 of the cap body. The protrusion 32 may be entirely inserted into the housing 20, or may be only partially inserted into the housing 20, which is not limited in this embodiment.

The portion of the protrusion 32 extending into the housing 20 may be an interference fit, a clearance fit, or a transition fit with the housing 20, which is not limited in this embodiment.

The position of the concave portion 33 corresponds to the position of the convex portion 32, and the concave portion 33 is recessed with respect to the outer surface 312 of the cap body in a direction facing the electrode assembly 10. The concave portion 33 can reduce the strength of the convex portion 32 to provide better elasticity to the region of the end cap 30 corresponding to the convex portion 32.

In the present embodiment, the protrusion 32 can protrude into the housing 20 when the end cap 30 and the housing 20 are assembled, and cooperate with the housing 20 to define the position of the end cap 30, so that the difficulty of positioning the housing 20 and the end cap 30 is reduced, and the assembly efficiency of the battery cell 7 is improved. The housing 20 can define the position of the end cap 30 by the protrusion 32, which can reduce the offset and misalignment between the end cap 30 and the housing 20 during the process of connecting the end cap 30 and the housing 20, and improve the sealing performance. The concave portion 33 can reduce the strength of the convex portion 32, so that, when the convex portion 32 and the case 20 are pressed against each other, the convex portion 32 can release stress by deformation, reducing the pressing force and friction between the convex portion 32 and the case 20, reducing generated particles, reducing the risk of deformation of the case 20, and improving the safety performance of the battery cell 7.

In some embodiments, the bottom surface of the recess 33 is entirely closer to the electrode assembly 10 than the inner surface 311 of the cap body in the thickness direction Z of the end cap 30.

The present embodiment can ensure the depth of the first concave portion 33 to increase the degree of the convex portion 32 protruding the inner surface 311 of the cover body, so as to improve the matching effect between the convex portion 32 and the housing 20, increase the elasticity of the convex portion 32, reduce the pressing force and the friction force between the convex portion 32 and the housing 20, reduce the generated particles, reduce the risk of deformation of the housing 20, and improve the safety performance of the battery cell 7.

In some embodiments, the cover body 31 may be an annular flat plate structure, and the end cap 30 may further include a portion surrounded by the cover body 31.

In some embodiments, the housing 20 is welded to the end cap 30. Welding can achieve the connection between the shell 20 and the end cover 30 and can ensure the sealing performance.

In some embodiments, the electrode assembly 10 includes a body part 11, a first tab 12, and a second tab 13, the first tab 12 and the second tab 13 protruding from the body part 11, as viewed from the external shape of the electrode assembly 10. The first tab 12 is a part of the first pole piece which is not coated with an active material layer, and the second pole piece is a part of the second pole piece which is not coated with an active material layer. Correspondingly, one of the first tab 12 and the second tab 13 is a tab with positive polarity, and the other is a tab with negative polarity.

The first tab 12 and the second tab 13 may extend from the same side of the body 11, or may extend from opposite sides.

Illustratively, the first and second tabs 12 and 13 are respectively provided at both sides of the main body part 11, in other words, the first and second tabs 12 and 13 are respectively provided at both ends of the electrode assembly 10. Alternatively, the first tab 12 is located at one end of the electrode assembly 10 facing the end cap 30 and the second tab 13 is located at one end of the electrode assembly 10 facing away from the end cap 30.

Optionally, the first tab 12 is wound around the central axis of the electrode assembly 10 in a plurality of turns, in other words, the first tab 12 includes a plurality of tab layers. After winding, the first tab 12 is substantially cylindrical, and a gap is left between two adjacent tab layers. The embodiment of the application can process the first tab 12 to reduce the gap between tab layers, so that the first tab 12 is connected with other conductive structures conveniently. For example, the present embodiment may perform a flattening treatment on the first tab 12 to gather and bring together the end regions of the first tab 12 away from the main body portion 11; the flattening process forms a compact end surface at one end of the first tab 12 far away from the main body part 11, so that the gap between tab layers is reduced, and the first tab 12 is convenient to be connected with other conductive structures. Alternatively, the embodiment of the application can also fill a conductive material between two adjacent circles of tab layers to reduce the gap between the tab layers.

Alternatively, the second tab 13 is wound around the central axis of the electrode assembly 10 in a plurality of turns, and the second tab 13 includes a plurality of turns of tab layers. Illustratively, the second pole piece 13 is also subjected to a flattening treatment to reduce the gap between the pole piece layers of the second pole piece 13.

In some embodiments, the end of the electrode assembly 10 facing the end cap 30 is provided with a first tab 12, the first tab 12 being electrically connected to the end cap 30.

The end cap 30 may be directly connected to the first tab 12, for example, the end cap 30 may be directly welded to the first tab 12 to electrically connect the end cap 30 and the first tab 12. Alternatively, the end cap 30 may be indirectly connected to the first tab 12 via other conductive structures (e.g., current collecting member 50).

In this embodiment, the electric potential of the end cap 30 may be substantially the same as the electric potential of the first tab 12, so that the end cap 30 may serve as an output electrode of the battery cell 7, thereby omitting a conventional electrode terminal and simplifying the structure of the battery cell 7.

In some embodiments, the first tab 12 of the electrode assembly 10 is electrically connected to the case 20 through the end cap 30.

The present embodiment connects the case 20 to the first tab 12 of the electrode assembly 10 through the end cap 30 such that the potential of the case 20 is substantially the same as the potential of the first tab 12, and thus the case 20 itself can serve as an output electrode of the battery cell 7, thereby eliminating a conventional electrode terminal and simplifying the structure of the battery cell 7. When a plurality of battery cells 7 are assembled into a group, the housing 20 can be electrically connected to the bus bar, which can increase the flow area and also can make the structural design of the bus bar more flexible.

In some embodiments, the case 20 includes a side wall 22 and a bottom wall 23, the side wall 22 extends in the thickness direction Z of the end cap 30 and is disposed around the outer circumference of the electrode assembly 10, the bottom wall 23 is connected to one end of the side wall 22 and is located on a side of the electrode assembly 10 facing away from the end cap 30, and the bottom wall 23 is provided with an electrode lead-out hole 231. The electrode assembly 10 is provided with a second tab 13 at an end facing the bottom wall 23, the first tab 12 and the second tab 13 being of opposite polarity. The battery cell 7 further includes an electrode terminal 40 mounted to the electrode lead-out hole 231, the electrode terminal 40 being electrically connected to the second tab 13.

The side wall 22 and the bottom wall 23 may be integrally formed structures, i.e., the housing 20 is an integrally formed member. Of course, the side wall 22 and the bottom wall 23 may also be two members separately provided and then joined together by welding, riveting, bonding, or the like.

The side wall 22 is a cylindrical structure, for example, the side wall 22 may be a cylinder or a square cylinder; the bottom wall 23 is a plate-like structure having a shape corresponding to the shape of the side wall 22. Alternatively, one end of the side wall 22 forms the opening 21, and the bottom wall 23 is connected to the other end of the side wall 22 facing away from the opening 21.

The second tab 13 may be electrically connected to the electrode terminal 40 directly or may be electrically connected to the electrode terminal 40 indirectly through another conductive structure.

The electrode terminal 40 is insulated from the bottom wall 23, the electrode terminal 40 and the bottom wall 23 may have different polarities, and the electrode terminal 40 and the bottom wall 23 may respectively serve as two output poles of the battery cell 7. Optionally, the battery cell 7 further includes an insulating member, at least a portion of which is located between the bottom wall 23 and the electrode terminal 40 to insulate and separate the bottom wall 23 and the electrode terminal 40.

When the first tab 12 is a negative tab and the second tab 13 is a positive tab, the bottom wall 23 is a negative output electrode of the battery cell 7, and the electrode terminal 40 is a positive output electrode of the battery cell 7. When the first tab 12 is a positive tab and the second tab 13 is a negative tab, the bottom wall 23 is a positive output electrode of the battery cell 7, and the electrode terminal 40 is a negative output electrode of the battery cell 7.

The electrode terminal 40 is fixed to the bottom wall 23. The electrode terminal 40 may be integrally fixed to the outside of the bottom wall 23, or may be extended into the case 20 through the electrode lead-out hole 231.

The first tab 12 is located at one end of the electrode assembly 10 facing the end cap 30 so that the end cap 30 is electrically connected to the first tab 12; correspondingly, the second tab 13 is located at one end of the electrode assembly 10 facing the bottom wall 23 so that the electrode terminal 40 is electrically connected with the second tab 13. The first tab 12 and the second tab 13 are disposed at two ends of the electrode assembly 10, so that the risk of conduction of the first tab 12 and the second tab 13 can be reduced, and the flow area of the first tab 12 and the flow area of the second tab 13 can be increased.

In the present embodiment, the bottom wall 23 and the electrode terminals 40 may serve as two output electrodes of the battery cell 7, which may simplify the structure of the battery cell 7 and secure the overcurrent capability of the battery cell 7. The bottom wall 23 and the electrode terminals 40 are located at the same end of the battery cell 7, so that the bus bar member can be assembled to the same side of the battery cell 7, which can simplify the assembly process and improve the efficiency of assembling a plurality of battery cells 7 into a group.

In some embodiments, bottom wall 23 and side wall 22 are integrally formed structures. This embodiment can omit the connecting process of the bottom wall 23 and the side wall 22 and reduce the resistance therebetween. For example, the housing 20 may be formed by a drawing process.

The electrode lead-out hole 231 of the embodiment of the present application is formed after the housing 20 is stretch-molded.

The inventors have attempted to roll the open end of the shell so that the open end of the shell is folded inwardly and forms a flange structure which presses against the end cap to effect securement of the end cap. The inventors mounted the electrode terminals to the end cap and used the burring structure and the electrode terminals as two output poles of the battery cell. However, the larger the size of the cuff structure, the higher the risk of curling and creasing after forming; if the burring structure is curled and wrinkled, unevenness of the surface of the burring structure may be caused, and there may be a problem of poor welding when the burring structure is welded with the bus bar member. Therefore, the size of the flanging structure is limited, and the overcurrent capacity of the battery monomer is insufficient.

The present embodiment forms an electrode lead-out hole 231 for mounting the electrode terminal 40 on the bottom wall 23 using a punching process to dispose the positive and negative output electrodes at one end of the battery cell 7 facing away from the opening 21; the bottom wall 23 is formed in the molding process of the housing 20, and the flatness of the bottom wall 23 can be ensured even after the electrode lead-out hole 231 is formed, so that the connection strength between the bottom wall 23 and the bus member can be ensured. Meanwhile, the flatness of the bottom wall 23 is not restricted by its size, so that the bottom wall 23 can have a larger size, thereby improving the overcurrent capacity of the battery cell 7.

In some embodiments, the first tab 12 is a negative tab, and the base material of the casing 20 is steel.

The case 20 is electrically connected to the negative electrode tab, i.e., the case 20 is in a low potential state. The steel case 20 is not easily corroded by the electrolyte in a low potential state, so that the safety risk is reduced.

In some embodiments, the base material of the housing 20 is the same as the base material of the end cap 30. Optionally, the base material of the housing 20 and the base material of the end cap 30 are both steel.

In this embodiment, the base material of the case 20 is the same as the base material of the end cap 30, so that the welding strength between the case 20 and the end cap 30 can be ensured, and the sealing performance of the battery cell 7 can be improved.

In some embodiments, the battery cell is a cylindrical battery cell. Correspondingly, the electrode assembly 10 has a cylindrical structure, and the case 20 has a cylindrical hollow structure.

In some embodiments, the protrusion 32 may support the first tab 12 directly or may support the first tab 12 through other members.

In some embodiments, the protrusion 32 abuts the first tab 12 of the electrode assembly 10 to support the first tab 12.

In the present embodiment, the protrusion 32 may support the first tab 12 to reduce the sloshing amplitude of the electrode assembly 10 when the battery cell 7 vibrates, and improve the stability of the electrode assembly 10.

In some embodiments, the tab is welded to the first tab to electrically connect the first tab to the end cap.

This embodiment can directly weld the protrusion 32 to the first tab 12 without using other coupling members, thereby simplifying the structure of the battery cell 7. The thickness of the convex portion 32 is reduced by providing the concave portion 33, so that the welding power required for welding the convex portion 32 with the first tab 12 can be reduced, heat generation is reduced, and the risk of burning other components is reduced.

In some embodiments, the boss 32 is configured to cooperate with the housing 20 to define the position of the end cap 30 in the radial direction.

The housing 20 has a central axis about which the side wall 22 is disposed. The central axis of the housing 20 extends in the thickness direction Z of the end cap 30. In the description of the present application, the radial direction is a direction perpendicular to the thickness direction Z and passing through the central axis.

The radial directions described herein apply to cylindrical cells. In the cylindrical battery cell, the electrode assembly 10 has a cylindrical structure, the case 20 has a cylindrical hollow structure, and the end cap 30 has a circular plate structure. For a cylindrical cell, "radial" may be the radial direction of the housing 20.

Of course, the radial directions described in the present application are also applicable to prismatic cells. In the case of a square battery cell, the electrode assembly 10 has a flat structure, the case 20 has a square hollow structure, and the cap 30 has a square plate-shaped structure.

In some embodiments, the side wall 22 of the case 20 extends in the thickness direction Z of the end cap 30 and is disposed around the outer circumference of the electrode assembly 10, and the inner wall surface 221 of the side wall and the outer circumferential surface 321 of the convex portion are both parallel to the thickness direction Z and are disposed opposite to each other.

Side wall 22 of case 20 has an inner wall surface and an outer wall surface disposed opposite to each other, and inner wall surface 221 of the side wall faces electrode assembly 10. The inner wall surface 221 of the side wall and the outer wall surface 222 of the side wall are both cylindrical surfaces. The inner wall surface 221 of the side wall is a curved surface formed by parallel movement of the first bus along a predetermined trajectory. Alternatively, the inner wall surface 221 of the side wall is a cylindrical surface, that is, the inner wall surface 221 of the side wall is a curved surface formed by parallel movement of the first generatrix along a circular trajectory. Alternatively, the outer wall surface 222 of the side wall is also a cylindrical surface.

The outer peripheral surface 321 of the convex portion is a cylindrical surface. The outer peripheral surface 321 of the convex portion is a curved surface formed by parallel movement of the second bus bar along a predetermined trajectory. Alternatively, the outer peripheral surface 321 of the convex portion is a cylindrical surface.

When the first bus bar is parallel to the second bus bar, the outer peripheral surface 321 of the convex portion is parallel to the inner wall surface 221 of the side wall. Illustratively, the first and second generatrices are both straight lines parallel to the thickness direction Z.

The inner wall surface 221 of the side wall surrounds the outer peripheral surface 321 of the protrusion, so that the inner wall surface 221 of the side wall can restrict the position of the end cap 30 by the outer peripheral surface 321 of the protrusion after the protrusion 32 protrudes into the housing 20.

In the present embodiment, the inner wall surface 221 of the side wall and the outer peripheral surface 321 of the convex portion are arranged in parallel, so that when the inner wall surface 221 of the side wall and the outer peripheral surface 321 of the convex portion contact and press each other, the stress between the two is relatively uniform, thereby reducing stress concentration and deformation of the housing 20 and the convex portion 32.

In some embodiments, the sidewall 22 of the housing 20 and the protrusion 32 are interference fit such that the inner wall surface 221 of the sidewall and the outer peripheral surface 321 of the protrusion are abutted.

The portion of the protrusion 32 extending into the housing 20 may be in interference fit with the housing 20 as a whole, or may be in interference fit with the housing 20 locally.

Taking the outer peripheral surface 321 of the protrusion and the inner wall surface 221 of the sidewall as cylindrical surfaces as an example, the outer peripheral surface 321 of the protrusion has a diameter larger than that of the inner wall surface 221 of the sidewall before the end cap 30 and the housing 20 are assembled, so that the portion of the protrusion 32 extending into the housing 20 is interference-fitted with the housing 20 after the protrusion 32 extends into the housing 20.

In this embodiment, the interference fit may increase the strength of the connection between the housing 20 and the end cap 30, improving the sealing performance. The present embodiment reduces the strength of the protrusion 32 by providing the recess 33, so as to reduce the acting force between the protrusion 32 and the housing 20 during the process of the protrusion 32 extending into the housing 20, and thus, even if the housing 20 and the protrusion 32 are in interference fit, the particles generated can be reduced, the risk of deformation of the housing 20 is reduced, and the safety performance of the battery cell 7 is improved.

In some embodiments, the inner wall surface 221 of the sidewall is welded to the outer peripheral surface 321 of the protrusion and forms a first weld W1. In the thickness direction Z, the first weld W1 does not extend beyond the outer surface 312 of the cap body in a direction away from the electrode assembly 10.

Alternatively, the protrusion 32 and the side wall 22 are joined by laser welding. When the projection 32 and the side wall 22 are welded, laser light is irradiated to the boundary between the outer peripheral surface 321 of the projection and the inner wall surface 221 of the side wall, and the laser light melts and connects at least a part of the outer peripheral surface 321 of the projection and a part of the inner wall surface 221 of the side wall.

In the present embodiment, the first welded portion W1 closes the opening 21 to achieve sealing, reducing the risk of leakage of the electrolytic solution from between the outer peripheral surface 321 of the convex portion and the inner wall surface 221 of the side wall.

When welding the protrusion 32 with the housing 20, if the protrusion 32 is interference-fitted with the housing 20, no external device is required to fix the end cap 30, thereby simplifying the assembly process. In addition, the outer peripheral surface 321 of the projection abuts against the inner wall surface 221 of the sidewall, so that the risk of burning of the electrode assembly 10 by the laser light incident into the case 20 can be reduced. The interference fit also blocks gas byproducts generated by welding, reduces gas byproducts passing between the outer peripheral surface 321 of the boss and the inner wall surface 221 of the sidewall, and reduces the risk of burning of the separator of the electrode assembly.

In the present embodiment, the exposed surface of the first weld W1 does not exceed the outer surface 312 of the cap body in the direction away from the electrode assembly 10 in the thickness direction Z.

The cover body 31 serves as a load-bearing structure of the battery cell 7. After the battery cell 7 is mounted to the electric device, the external support structure may support the battery cell 7 through the cover body 31. The present embodiment does not allow the first welding part W1 to exceed the outer surface 312 of the cap body in a direction away from the electrode assembly 10, so as to reduce the force applied between the external support structure and the first welding part W1, reduce the risk of breakage of the first welding part W1, and ensure the connection strength and sealing performance between the case 20 and the end cap 30.

In some embodiments, sidewall 22 includes a first outer end face 223 surrounding opening 21, first outer end face 223 being connected to inner wall surface 221 of the sidewall. In the thickness direction Z, the convex portion 32 has a second outer end surface 322 at an end facing away from the electrode assembly 10, the second outer end surface 322 is connected to the outer peripheral surface 321 of the convex portion, the first outer end surface 223 and the second outer end surface 322 are flush, and the first outer end surface 223 and the second outer end surface 322 are closer to the electrode assembly 10 than the outer surface 312 of the cap body.

The first outer end face 223 connects the inner wall surface 221 of the side wall and the outer wall surface 222 of the side wall. One end of the second outer end surface 322 facing away from the outer peripheral surface 321 of the convex portion is connected to the side wall surface of the concave portion 33.

Alternatively, first outer end face 223 and second outer end face 322 are both perpendicular to inner wall surface 221 of the sidewall and outer peripheral surface 321 of the protrusion.

The first welding portion W1 formed by welding is uneven and may protrude from the first and second outer end surfaces 223 and 322, and if the first outer end surface 223 is flush with the outer surface 312 of the cap body, the first welding portion W1 may serve as a load-bearing portion of the battery cell 7, causing a risk of breakage of the first welding portion W1.

The present embodiment brings the first and second outer end surfaces 223 and 322 closer to the electrode assembly 10 than the outer surface 312 of the cap body, and thus, even if the first weld W1 protrudes from the first and second outer end surfaces 223 and 322, the first weld W1 can be prevented from exceeding the outer surface 312 of the cap body in a direction away from the electrode assembly 10, so that an acting force applied to the first weld W1 is reduced, a risk of fracture of the first weld W1 is reduced, and a connection strength and a sealing performance between the case 20 and the end cap 30 are ensured.

In some embodiments, the protrusion 32 further includes a guide surface 323 facing the side wall 22, the guide surface 323 is connected to an end of the outer circumferential surface 321 of the protrusion near the electrode assembly 10, and the guide surface 323 is inclined in a direction away from the inner wall surface 221 of the side wall compared to the outer circumferential surface 321 of the protrusion to guide the protrusion 32 to protrude into the case 20.

The guide surface 323 is spaced apart from the inner wall surface 221 of the side wall. The distance between the guide surface 323 and the inner wall surface 221 of the side wall in the radial direction gradually increases in the direction from the end cap 30 toward the electrode assembly 10.

The present embodiment can guide the insertion of the protrusion 32 into the housing 20 when assembling the end cap 30 and the housing 20 (especially when the protrusion 32 is in interference fit with the housing 20) by providing the inclined guide surface 323 on the protrusion 32, so as to simplify the assembly process and improve the assembly efficiency.

Fig. 7 is a schematic cross-sectional view of a battery cell according to another embodiment of the present application.

In some embodiments, the case 20 further includes a burring 24, and the burring 24 is connected to the side wall 22 and is bent toward the cover body 31 with respect to the side wall 22 to cover the first welding portion W1.

The hem 24 is of unitary construction with the side wall 22 and is formed by a hemming process.

The end of the turn-up portion 24 facing away from the side wall 22 forms an opening 21.

In assembling the end cap 30 and the case 20, the projection 32 of the end cap 30 is inserted into the case 20, and then the projection 32 and the side wall 22 are welded and the first weld W1 is formed. After the welding is completed, a portion of the case 20 near the opening 21 is rolled to form a burring 24 covering the first welded portion W1.

In the present embodiment, the burring 24 protects the first weld W1, reduces the risk of corrosion and damage to the first weld W1, and ensures the connection strength and sealing performance between the case 20 and the end cap 30.

In some embodiments, the surface of the burring 24 facing away from the electrode assembly 10 is flush with the outer surface of the cover body.

Fig. 8 is a schematic cross-sectional view of a battery cell provided in accordance with further embodiments of the present application; fig. 9 is an enlarged schematic view of the battery cell shown in fig. 8 at a circle frame B; fig. 10 is an enlarged schematic view of fig. 9 at block C.

As shown in fig. 8 to 10, in some embodiments, the end cap 30 further includes an extension portion 36 protruding from the outer circumferential surface 321 of the protrusion and surrounding the outer side of the protrusion 32, and an inner surface 361 of the extension portion is welded to the first outer end surface 223 of the sidewall 22 surrounding the opening, so that the housing 20 and the end cap 30 are integrally connected.

The extension 36 includes an inner surface and an outer surface oppositely disposed in the thickness direction Z, and the inner surface 361 of the extension faces the electrode assembly 10. Optionally, the extension 36 is an annular flat plate structure, and both the inner surface 361 of the extension and the outer surface 362 of the extension are planar.

The extension 36 and the sidewall 22 are arranged in the thickness direction Z, and an inner surface 361 of the extension may be disposed in parallel with the first outer end surface 223.

Alternatively, when welding the extension 36 and the sidewall 22, laser light is irradiated at the intersection of the first outer end face 223 and the inner surface 361 of the extension; after welding, at least part of the inner surface 361 of the extension and at least part of the first outer end face 223 are melted and joined together.

The inner surface 361 of the extension is welded to the first outer end face 223 of the sidewall 22 and forms a second weld W2.

The first outer end face 223 is at the outermost end of the housing 20, and the present embodiment abuts the inner surface 361 of the extension against the first outer end face 223.

In this embodiment, when the end cap 30 and the housing 20 are assembled, the first outer end surface 223 may play a role of limiting in the thickness direction Z of the end cap 30, so as to reduce the risk that the end cap 30 is excessively inserted into the housing 20, and improve the assembly efficiency.

In some embodiments, the protrusion 32 and the housing 20 are clearance fit to form a gap between the outer peripheral surface 321 of the protrusion and the inner wall surface 221 of the sidewall.

Taking the outer peripheral surface 321 of the projection and the inner wall surface 221 of the side wall as an example of a cylindrical surface, the outer peripheral surface 321 of the projection has a smaller diameter than the inner wall surface 221 of the side wall before the end cap 30 and the housing 20 are assembled, so that the portion of the projection 32 extending into the housing 20 is in clearance fit with the housing 20 after the projection 32 extends into the housing 20.

In the embodiment, the clearance fit not only can ensure the limitation of the housing 20 to the protrusion 32, but also can reduce the acting force between the protrusion 32 and the housing 20 in the process that the protrusion 32 extends into the housing 20, reduce the risk of friction between the protrusion 32 and the housing 20, reduce the generated particles, reduce the deformation of the housing 20, and improve the safety performance of the battery cell 7.

In some embodiments, the gap between outer peripheral surface 321 of the protrusion and inner wall surface 221 of the sidewall has a size of 0.02mm to 0.5mm in a direction from electrode assembly 10 toward sidewall 22.

Illustratively, "in a direction pointing from the electrode assembly toward the sidewall" may be a radial direction.

Illustratively, the gap between the outer peripheral surface 321 of the projection and the inner wall surface 221 of the side wall has a dimension L1 in a direction from the electrode assembly 10 toward the side wall 22. The smaller the value of L1, the higher the risk of rubbing the outer peripheral surface 321 of the convex portion against the inner wall surface 221 of the side wall, and the higher the risk of generating particles; the larger the value of L1, the larger the range in which the projection 32 can move after the projection 32 is inserted into the housing 20, and the higher the risk of poor welding between the extension 36 and the housing 20. The inventor tests to set the value of L1 to be 0.02mm-0.5mm so as to balance risks and improve safety performance.

In some embodiments, the inner surface 361 of the extension is provided with an avoiding groove 363, the avoiding groove 363 surrounds the outer side of the protrusion 32, and the groove wall surface of the avoiding groove 363 is used for connecting the inner surface 361 of the extension and the outer circumferential surface 321 of the protrusion.

The concave portion 33 and the convex portion 32 may be formed by a process of stamping. The inventor finds that stress concentration is generated at the joint of the convex part and the extending part in the process of stamping forming; to reduce stress concentrations, the inventors tried to provide a fillet at the junction of the protrusion and the extension. However, after press forming, a rounded surface is formed at the junction of the inner surface and the outer peripheral surface of the extension portion, and the rounded surface is relatively smooth and may abut against the first outer end surface during insertion of the protrusion into the housing, so that the first outer end surface cannot be closely attached to the inner surface of the extension portion.

In view of this, the inventor provided an avoidance groove 363 on the extension 36, and a portion of the extension 36 opposite to the avoidance groove 363 was connected to the convex portion 32. The avoiding groove 363 is recessed to provide a flowing space for the material when the convex portion 32 is molded, so that a rounded corner is formed at a portion of the extending portion 36 opposite to the avoiding groove 363, and a surface of the rounded corner is a portion of a groove wall surface of the avoiding groove 363; and the groove wall surface is recessed with respect to the inner surface 361 of the extension portion, therefore, the present embodiment can ensure that the first outer end surface 223 smoothly abuts against the inner surface 361 of the extension portion.

In some embodiments, the outer surface 362 of the extension is flush with the outer surface 312 of the cap body.

In the present embodiment, the external support structure can support the battery cell 7 through the extension portion 36 and the cover body 31, so that the area of the load-bearing portion of the end cover 30 can be increased, and the stability of the battery cell 7 can be improved.

In some embodiments, extension 36 does not extend beyond outer wall surface 222 of the side wall in a direction from electrode assembly 10 toward side wall 22.

This embodiment can avoid the extension portion 36 from increasing the maximum size of the battery cell 7, and ensure the energy density of the battery cell 7. In addition, the end cap 30 is thin and may scratch other external components if the extension 36 extends beyond the outer wall 222 of the sidewall.

In some embodiments, outer wall 222 of the sidewall extends 0.02mm to 0.5mm beyond the extension in a direction from electrode assembly 10 toward sidewall 22.

The second welded part W2 formed by welding the inner surface 361 of the extension part and the first outer end surface 223 of the side wall 22 protrudes beyond the end surface 364 of the extension part 36, and if the outer wall surface 222 of the side wall is flush with the end surface 364 of the extension part 36 facing away from the protrusion 32, the second welded part W2 may protrude beyond the outer wall surface 222 of the side wall, increase the maximum size of the battery cell 7, and easily scratch other external components. Therefore, the present embodiment makes the outer wall surface 222 of the sidewall exceed the extension portion 36 to reduce the risk of the second welding portion W2 protruding the outer wall surface 222 of the sidewall.

The outer wall surface 222 of the side wall has a dimension L2 beyond the extension 36 in a direction from the electrode assembly 10 toward the side wall 22. The smaller the value of L2, the higher the risk that the second welding portion W2 protrudes from the outer wall surface 222 of the side wall; the larger the value of L2, the smaller the connection area between the extension 36 and the side wall 22, and the lower the connection strength between the extension 36 and the side wall 22.

The inventors have experimented with that the value of L2 is set to 0.02mm to 0.5mm in order to reduce the risk of the second weld W2 protruding beyond the outer wall surface 222 of the side wall as much as possible while ensuring the connection strength.

In some embodiments, the dimension L3 of the outer peripheral surface 321 of the protruding part of the extension 36 in the direction from the electrode assembly 10 toward the side wall 22 is smaller than the wall thickness of the side wall 22.

Illustratively, L3 is the distance in the radial direction between the end surface 364 of the extension 36 and the outer peripheral surface 321 of the projection.

In the present embodiment, when the outer peripheral surface 321 of the protrusion abuts against the inner wall surface 221 of the side wall, since the wall thickness of the side wall 22 is larger than the size of the extension portion 36 protruding the outer peripheral surface 321 of the protrusion, the outer wall surface 222 of the side wall exceeds the extension portion 36 in the direction of the electrode assembly 10 toward the side wall 22.

Fig. 11 is a schematic flow chart of a method for manufacturing a battery cell according to some embodiments of the present disclosure.

As shown in fig. 11, the method for manufacturing a battery cell according to the embodiment of the present application includes:

s100, providing a shell, wherein the shell is provided with an opening;

s200, providing an electrode assembly, and mounting the electrode assembly into a shell;

s300, providing an end cover, wherein the end cover comprises a cover body and a convex part surrounding the outer side of the cover body, the convex part protrudes out of the inner surface of the cover body, a concave part is formed in the position, corresponding to the convex part, of the end cover, and the concave part is sunken from the outer surface of the cover body;

s400, extending at least part of the convex part into the shell and matching the convex part with the shell;

s500, connecting the end cover and the shell to enable the end cover to cover the opening;

wherein the convex portion protrudes from the inner surface of the cap body in a direction facing the electrode assembly, the concave portion is recessed from the outer surface of the cap body in a direction facing the electrode assembly, and the concave portion is used to release stress during the protrusion protrudes into the case.

For the structure of the battery cell manufactured by the above method, reference may be made to the battery cells provided in the above embodiments.

When the battery cell is assembled based on the above-described method for manufacturing the battery cell, the steps need not be performed sequentially, that is, the steps may be performed in the order mentioned in the embodiments, may be performed in an order different from the order mentioned in the embodiments, or may be performed simultaneously. For example, steps S100 and S300 may be executed simultaneously without being performed sequentially.

Fig. 12 is a schematic block diagram of a system for manufacturing a battery cell provided in some embodiments of the present application.

As shown in fig. 12, a system 90 for manufacturing a battery cell according to an embodiment of the present application includes:

a first providing means 91 for providing a housing having an opening;

a second supply means 92 for supplying the electrode assembly and mounting the electrode assembly in the case;

a third providing device 93 for providing an end cover, wherein the end cover comprises a cover body and a convex part surrounding the outer side of the cover body, the convex part protrudes out of the inner surface of the cover body, a concave part is formed on the end cover at a position corresponding to the convex part, and the concave part is sunken from the outer surface of the cover body;

first assembly means 94 for extending at least part of the male portion into the housing and for engaging the housing;

a second assembly device 95 connecting the end cap and the housing to cover the opening;

wherein the convex portion protrudes from the inner surface of the cap body in a direction facing the electrode assembly, the concave portion is recessed from the outer surface of the cap body in a direction facing the electrode assembly, and the concave portion is used to release stress during the protrusion protrudes into the case.

For the structure of the battery cell manufactured by the manufacturing system, reference may be made to the battery cell provided in each of the above embodiments.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit 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: it is to be understood that modifications may be made to the above-described embodiments, or equivalents may be substituted for some of the features of the embodiments, without departing from the spirit or scope of the claims.

Claims (23)

1. A battery cell, comprising:

a housing having an opening;

the electrode assembly is accommodated in the shell, and one end, facing the opening, of the electrode assembly is provided with a first tab; and

an end cap for covering the opening, the end cap including a cap body and a protrusion surrounding an outer side of the cap body, the protrusion protruding from an inner surface of the cap body in a direction facing the electrode assembly, and at least a portion of the protrusion being located within the case and adapted to fit with the case;

wherein a concave portion is formed on the end cap at a position corresponding to the convex portion, the concave portion being depressed from the outer surface of the cap body in a direction facing the electrode assembly and serving to release stress in a process in which the convex portion protrudes into the case.

2. The battery cell according to claim 1, wherein a bottom surface of the recess is closer to the electrode assembly as a whole than an inner surface of the cap body in a thickness direction of the end cap.

3. The battery cell according to claim 1 or 2, wherein a side wall of the case extends in a thickness direction of the end cap and is disposed around an outer periphery of the electrode assembly, and an inner wall surface of the side wall and an outer peripheral surface of the convex portion are both parallel to the thickness direction and are disposed opposite to each other.

4. The battery cell according to claim 3, wherein the side wall of the case and the convex portion are interference-fitted so that an inner wall surface of the side wall and an outer peripheral surface of the convex portion are abutted.

5. The battery cell according to claim 3, wherein an inner wall surface of the side wall is welded to an outer peripheral surface of the convex portion and forms a first welded portion;

in the thickness direction, the first weld does not extend beyond the outer surface of the cap body in a direction away from the electrode assembly.

6. The battery cell as recited in claim 5 wherein the sidewall includes a first outer end face surrounding the opening, the first outer end face being connected to an inner wall surface of the sidewall;

the convex portion has a second outer end surface at an end facing away from the electrode assembly in the thickness direction, the second outer end surface is connected to an outer peripheral surface of the convex portion, the first outer end surface and the second outer end surface are flush, and the first outer end surface and the second outer end surface are closer to the electrode assembly than an outer surface of the cap body.

7. The battery cell as recited in claim 5, wherein the case further comprises a flange portion connected to the side wall and bent toward the cover body with respect to the side wall to cover the first welding portion.

8. The battery cell as recited in claim 3, wherein the end cap further includes an extension portion protruding from an outer circumferential surface of the protrusion and surrounding an outer side of the protrusion, an inner surface of the extension portion being welded to the first outer end surface of the side wall surrounding the opening to integrally connect the case and the end cap.

9. The battery cell as recited in claim 8, wherein the protrusion and the case are clearance-fitted to form a gap between an outer peripheral surface of the protrusion and an inner wall surface of the side wall.

10. The battery cell according to claim 9, wherein the gap between the outer peripheral surface of the convex portion and the inner wall surface of the side wall has a size of 0.02mm to 0.5mm in a direction from the electrode assembly toward the side wall.

11. The battery cell as recited in claim 8, wherein the inner surface of the extension portion is provided with an avoiding groove surrounding the outer side of the protrusion, and a groove wall surface of the avoiding groove is used for connecting the inner surface of the extension portion and the outer circumferential surface of the protrusion.

12. The battery cell of claim 8, wherein an outer surface of the extension is flush with an outer surface of the cover body.

13. The battery cell as recited in claim 8 wherein the extension does not extend beyond the outer wall surface of the side wall in a direction from the electrode assembly toward the side wall.

14. The battery cell as recited in claim 13 wherein the outer wall surface of the side wall extends 0.02mm to 0.5mm beyond the extension in a direction from the electrode assembly toward the side wall.

15. The battery cell as recited in claim 13 wherein the extension projects beyond the outer peripheral surface of the protrusion by a dimension less than the wall thickness of the sidewall in a direction from the electrode assembly toward the sidewall.

16. The battery cell as recited in claim 3 wherein the protrusion further comprises a guide surface facing the side wall, the guide surface being connected to an end of an outer peripheral surface of the protrusion near the electrode assembly, and the guide surface being inclined in a direction away from an inner wall surface of the side wall relative to the outer peripheral surface of the protrusion to guide the protrusion to protrude into the case.

17. The battery cell as recited in claim 1, wherein the protrusion abuts against the first tab to support the first tab.

18. The battery cell as recited in claim 17 wherein the tab is welded to the first tab to electrically connect the first tab to the end cap.

19. The battery cell as recited in claim 1 wherein the first tab is electrically connected to the housing through the end cap.

20. The battery cell as recited in claim 19, wherein the case includes a side wall extending in a thickness direction of the end cap and disposed around an outer periphery of the electrode assembly, and a bottom wall connected to one end of the side wall and located on a side of the electrode assembly facing away from the end cap, the bottom wall being provided with an electrode lead-out hole;

the electrode assembly is provided with a second lug at one end facing the bottom wall, and the first lug and the second lug are opposite in polarity;

the single battery also comprises an electrode terminal arranged in the electrode leading-out hole, and the electrode terminal is electrically connected with the second pole lug.

21. The battery cell as recited in claim 20 wherein the bottom wall and the side wall are an integrally formed structure.

22. A battery comprising a plurality of battery cells according to any one of claims 1-21.

23. An electrical device comprising a battery according to claim 22 for providing electrical energy.

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