CN216389567U - Battery cell, battery and power consumption device - Google Patents

Abstract

The embodiment of the application provides a battery monomer, battery and electric installation, and this battery monomer includes: an electrode assembly; the shell is used for accommodating the electrode assembly and is provided with an opening and a top end surface surrounding the periphery of the opening; the end cap is used for covering the opening, and comprises a cap body and a bulge body surrounding the periphery of the cap body, wherein the bulge body comprises an inner surface facing the electrode assembly and an outer surface facing away from the electrode assembly, the inner surface and the outer surface are oppositely arranged along the thickness direction of the end cap, and the inner surface is attached to the top end surface and is formed with a butt joint area; the shell and the end cover are welded into a whole and form a welding part, the welding part is configured to be at least partially formed on the butt joint area and is spaced from the outer surface by a first preset distance in the thickness direction, so that the welding part does not reach the outer surface, the welding part does not form a welding bulge on the outer surface, the appearance of the single battery does not change obviously, and the size precision of the single battery is improved.

Description

Battery cell, 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 the key points of sustainable development of the automobile industry. Under such circumstances, electric vehicles are an important component of sustainable development of the automobile industry due to their energy saving and environmental protection advantages. In the case of electric vehicles, battery technology is an important factor in the development thereof. The size precision of the battery monomer is ensured, and the safety and the reliability of the battery are improved.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides a single battery, a battery and an electric device, which can improve the size precision of the single battery and improve the safety and reliability of the battery.

In a first aspect, an embodiment of the present application provides a battery cell, including: an electrode assembly; a case for accommodating the electrode assembly, the case having an opening and a top end surface surrounding an outer periphery of the opening; an end cap for covering the opening, the end cap including a cap body and a projection surrounding an outer periphery of the cap body, the projection including an inner surface facing the electrode assembly and an outer surface facing away from the electrode assembly, the inner and outer surfaces being oppositely disposed in a thickness direction of the end cap, the inner surface being attached to the top end surface and formed with a butt joint region; the shell and the end cover are welded into a whole and form a welding part, the welding part is configured to be at least partially formed on the butt joint area and is separated from the outer surface in the thickness direction by a first preset distance, and the first preset distance is the minimum distance between the welding part and the outer surface in the thickness direction.

In the technical scheme, the end part of the outer surface of the welding part, which is far away from the electrode assembly, is separated from the outer surface by the first preset distance along the thickness direction of the end cover, so that the welding part does not reach the outer surface, the welding part does not form a welding bulge on the outer surface, the appearance of the battery cell does not change obviously, and the size precision of the battery cell is improved.

In some embodiments, the first predetermined distance f and the thickness h of the projection satisfy: 0.25h > f > 0.

In the technical scheme, the first preset distance f is larger than 0, so that the welding part can be kept at a certain distance from the outer surface, the outer surface cannot be melted, and the size precision of the battery cell cannot be influenced due to the fact that the outer surface is not bulged. Make first predetermined distance f be less than the thickness h of 0.25 times's bulge, make the bulge have sufficient width and weld with the casing to can guarantee the width of welding portion, guarantee welding strength, improve sealing performance.

In some embodiments, the cap body protrudes from the inner surface in a direction facing the electrode assembly; the butt fusion portion includes first butt fusion portion and second butt fusion portion, and first butt fusion portion is used for being connected the bulge body as an organic whole with the casing, and the lid body is located to the second butt fusion portion.

In above-mentioned technical scheme, the butt fusion portion extends to the lid body of end cover is inside, forms first butt fusion portion and second butt fusion portion, can guarantee butt fusion portion to the inside butt fusion degree of end cover, has improved the intensity of butt fusion portion.

In some embodiments, the cap body has a peripheral side surface and a chamfered surface which is obliquely arranged relative to the peripheral side surface and toward the interior of the housing, the peripheral side surface is arranged to be fitted with an inner wall surface of the housing, one end of the peripheral side surface is connected with the inner surface, and the other end is connected with the chamfered surface; the welding part and the chamfer surface are separated by a second preset distance in the thickness direction, and the second preset distance is the minimum distance between the welding part and the chamfer surface in the thickness direction.

In the above technical solution, the chamfered surface is provided at the edge of the end portion of the cap body on the side facing the electrode assembly, so that the cap body can be more easily fitted into the case when the end cap is closed. The distance between the end part of the welding part outer surface facing the electrode assembly and the end part connected with the chamfer surface and the peripheral side surface can be avoided, so that welding materials can be prevented from flowing into the interior of the battery cell from the position of the chamfer surface, the electrode assembly is prevented from being damaged, and the service rate of the battery cell is improved.

In some embodiments, the second predetermined distance e and the thickness b of the cap body satisfy: 0.25b ≧ e > 0.

In the technical scheme, the second preset distance e is larger than 0, a certain distance between the welding part and the chamfer surface can be ensured, the welding material is prevented from flowing into the single battery from the position of the chamfer surface, and the electrode assembly is prevented from being damaged. The thickness b of the cover body, which enables the second preset distance e to be smaller than 0.25 time, can ensure the width of the welding part, ensure the welding strength and improve the sealing performance.

In some embodiments, the first weld includes a first portion and a second portion on either side of the interface region, the first portion being closer to the outer surface than the second portion, the first portion and the second portion being symmetrically disposed with respect to the interface region.

In some embodiments, the extension plane of the butt-joint region passes through the tip line of the second weld.

In some embodiments, the maximum depth c of the weld in the first direction and the thickness d of the shell satisfy: c-d is more than or equal to 100 mu m, wherein the first direction is the direction of the convex body pointing to the cover body.

In the technical scheme, the maximum depth c of the welding part along the first direction is greater than the thickness d of the shell, and the distance extending towards the inside of the cover body is greater than 100 mu m, so that the depth of the welding part can be ensured, the strength of the welding part can be enhanced, and the sealing performance of the battery cell can be improved.

In some embodiments, the maximum width a of the weld in the thickness direction, the lid body thickness b, the first predetermined distance f, and the second predetermined distance e satisfy: a/b is more than or equal to 0.5 and less than 1, and f + a + e is more than or equal to b.

In above-mentioned technical scheme, can guarantee the intensity of welding portion to, avoid forming the arch on the surface, and avoid welding material to flow into inside the battery monomer.

In some embodiments, the thickness h of the projection is greater than the thickness d of the shell.

In the technical scheme, the width of the welding part can be ensured, meanwhile, the strength of the bulge body can be ensured, and the end cover is not deformed when the end cover bears the pressure in the thickness direction or is fixedly installed on the end cover.

In some embodiments, the thickness h of the projection and the thickness b of the cap body satisfy: h is more than or equal to 0.5b and more than or equal to 0.5 mm.

In the technical scheme, the strength of the bulge body can be ensured, and the width of the welding part can be ensured.

In some embodiments, the thickness b of the cap body satisfies: b is more than or equal to 1.5mm and more than or equal to 2.5 mm.

In the technical scheme, the welding strength of the welding part is ensured, and the requirement of a welding process can be met.

In some embodiments, the thickness d of the shell is ≧ 0.2 mm.

In the technical scheme, the thickness d of the shell needs to meet the strength requirement of the shell.

In a second aspect, an embodiment of the present application provides a battery, which includes a plurality of battery cells as described in the first aspect.

In a third aspect, an embodiment of the present application provides an electric device, which includes the battery according to the second aspect, and the battery is used for providing electric energy.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

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 a schematic structural view of a battery module provided in some embodiments of the present application;

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

fig. 5 is a schematic structural view of the battery cell in fig. 4;

fig. 6 is a sectional view of the battery cell of fig. 5 taken along a-a;

FIG. 7 is an enlarged view of a portion of FIG. 6 at B;

FIG. 8 is a schematic view of the end cap of FIG. 7 prior to welding with the housing;

FIG. 9 is an exploded view of the end cap of FIG. 8 prior to welding with the housing;

FIG. 10 is a dimensional relationship diagram of a weld of some embodiments.

Description of the labeling:

1-a vehicle;

2-a battery;

3-a controller;

4-a motor;

5-a box body;

51-a first tank portion;

52-a second tank portion;

53-an accommodation space;

200-a battery module;

20-a battery cell;

21-end cap;

211-electrode terminals;

212-a projection;

2121-inner surface;

2122-an outer surface;

213-a lid body;

2131-chamfering surface;

2132-peripheral flank;

22-an electrode assembly;

221-pole ear;

23-a housing;

231-an opening;

232-top end face;

233-inner wall surface;

24-a weld;

241-a first weld;

2411-a first part;

2412-a second part;

242 — a second weld;

2421-top line;

243-outer peripheral surface;

2431-highest point;

2432-nadir;

25-a docking area;

a-the maximum width of the weld in the thickness direction;

b-thickness of the lid body;

c-maximum depth of the weld in the first direction;

d-the thickness of the shell;

e-a second predetermined distance;

f-a first predetermined distance;

h-thickness of the projection.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.

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 above figures 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 appropriate.

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).

At present, the application of the power battery is more and more extensive 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 and aerospace. With the continuous expansion of the application field of the power battery, the market demand is also continuously expanding.

In the field of electric vehicles such as electric vehicles, the power battery is used as a core component of the vehicle, which is one of the most important standards for considering the performance of the power battery, with regard to the safety of the vehicle and the safety of the power battery.

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.

At present, a battery cell generally includes a casing, an electrode assembly, and an end cap, where the end cap covers an opening of the casing to provide a sealed space for the electrode assembly and an electrolyte, and the casing and the end cap are usually fixed by welding.

The electrode assembly consists of a positive pole piece, a negative pole piece and an isolating membrane. 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 includes anodal mass flow body and anodal active substance layer, and anodal active substance layer coats in anodal mass flow body's surface, and the anodal mass flow body protrusion in the anodal mass flow body on the anodal active substance layer of coating has not coated anodal active substance layer, and the anodal mass flow body on the anodal active substance layer of coating is as anodal utmost point ear. Taking a lithium ion battery as an example, the material of the positive electrode current collector may be aluminum, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, or the like. The negative pole piece includes negative pole mass flow body and negative pole active substance layer, and the negative pole active substance layer coats in the surface of negative pole mass flow body, and the negative pole mass flow body protrusion in the negative pole mass flow body of coating the negative pole active substance layer not coated on the negative pole active substance layer, and the negative pole mass flow body of not coating the negative pole active substance layer is as negative pole utmost point ear. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon, silicon, or the like. In order to ensure that the fuse is not fused when a large current is passed, the number of the positive electrode tabs is multiple and the positive electrode tabs are stacked together, and the number of the negative electrode tabs is multiple and the negative electrode tabs are stacked together. In addition, the electrode assembly may have a winding structure or a lamination structure, and the embodiment of the present application is not limited thereto.

The applicant found that forming a protrusion in the height direction or the width direction of the battery cell after welding the case and the end cap seriously affects the appearance of the battery cell and makes the size of the battery cell inconsistent, and when a plurality of battery cells are combined into a battery or a battery module, the mounting accuracy is affected, and the energy density of the battery is reduced.

In view of this, the embodiment of the present application provides a technical solution, and through improving the welding seam structure of the casing and the end cover, the bulge generated by the welding seam is reduced, the installation accuracy of the battery cell is improved, and the energy density of the battery is improved.

The technical scheme described in the embodiment of the application is suitable for the battery module and the battery composed of the battery module.

The device using the battery may 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, and spacecraft, among others; 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-described device using a battery.

For convenience of explanation, the following embodiments will be described by taking a device using a battery as an example of a vehicle.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a vehicle 1 according to some embodiments of the present disclosure. As shown in fig. 1, a battery 2 is disposed inside a vehicle 1, and the battery 2 refers to a single physical module including one or more battery cells to provide higher voltage and capacity, for example, the battery 2 mentioned in this application may include a battery module or a battery pack, etc. The battery 2 may be disposed at the bottom or the head or the 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.

Referring to fig. 2, fig. 2 is an exploded view of a battery 2 according to some embodiments of the present disclosure.

As shown in fig. 2, the battery 2 includes a case 5 and a battery cell 20, and the battery cell 20 is accommodated in the case 5.

The case 5 is used for accommodating the battery cells 20, and the case 5 may have various structures. In some embodiments, the box body 5 may include a first box body portion 51 and a second box body portion 52, the first box body portion 51 and the second box body portion 52 cover each other, and the first box body portion 51 and the second box body portion 52 jointly define a receiving space 53 for receiving the battery cell 21. The second casing part 52 may be a hollow structure with one open end, the first casing part 51 may be a plate-shaped structure, and the first casing part 51 covers the open side of the second casing part 52 to form the casing 5 with the accommodating space 53; the first casing portion 51 and the second casing portion 52 may be hollow structures each having one side opened, and the opening side of the first casing portion 51 may be covered with the opening side of the second casing portion 52 to form the casing 5 having the accommodating space 53. Of course, the first and second casing portions 51 and 52 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 51 and the second casing portion 52 are connected, a sealing member, such as a sealant or a gasket, may be provided between the first casing portion 51 and the second casing portion 52.

Assuming that the first box portion 51 covers the top of the second box portion 52, the first box portion 51 may also be referred to as an upper box cover, and the second box portion 52 may also be referred to as a lower box body.

In the battery 2, there are a plurality of battery cells 20. The plurality of battery cells 20 may be connected in series, in parallel, or in series-parallel, where in series-parallel refers to both series connection and parallel connection among the plurality of battery cells 20. The plurality of battery monomers 20 can be directly connected in series or in parallel or in series-parallel, and the whole formed by the plurality of battery monomers 20 is accommodated in the box body 5; of course, a plurality of battery cells 20 may be connected in series, in parallel, or in series-parallel to form a battery pack, and a plurality of battery packs may be connected in series, in parallel, or in series-parallel to form a whole and accommodated in the box 5.

The number of the battery cells 20 may be set to any number according to different power requirements. A plurality of battery cells 20 may be connected in series, parallel, or series-parallel to achieve greater capacity or power. The plurality of battery cells 20 may also be connected in series, in parallel, or in series-parallel to form a battery module, and then the plurality of battery modules are connected in series, in parallel, or in series-parallel to form the battery 2. That is, the plurality of battery cells 20 may directly constitute the battery 2, or may be first constituted as a battery module, and then the battery 2 is constituted as a battery module, and accommodated in the case 5.

Referring to fig. 3, fig. 3 is a schematic structural diagram of a battery module 200 according to an embodiment of the present disclosure. As shown in fig. 3, since the number of the battery cells 20 included in each battery 2 may be large, the battery cells 20 may be arranged in groups for convenience of installation, each group of the battery cells 20 constituting the battery module 200. The battery 2 may include a plurality of battery modules 200, and the battery modules 200 may be connected in series, parallel, or series-parallel.

Fig. 4 is an exploded view of a battery cell 20 according to some embodiments of the present disclosure. Referring to fig. 4, the battery cell 20 refers to a minimum constituent unit for forming the battery 2, and in some embodiments of the present application, the battery cell 20 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, a magnesium ion battery cell, or the like, which is not limited in the embodiments of the present application. The battery cells 20 may have a cylindrical shape, a flat shape, a rectangular parallelepiped shape, or other shapes, which is not limited in the embodiments of the present application, and for convenience of description, the battery cells 20 having a rectangular parallelepiped shape are exemplified in the following embodiments.

With continued reference to fig. 4, the battery cell 20 includes an end cap 21, an electrode assembly 22, and a case 23. The case 23 serves to accommodate the electrode assembly 22 within the case 23. The case 23 may be various shapes and various sizes, and in particular, the shape of the case 23 may be determined according to the specific shape and size of one or more electrode assemblies 22. In some embodiments, the housing 23 is a hollow cuboid. In other embodiments, the housing 23 may be cylindrical or other shape. One end of the case 23 is an opening 231, and the end cap 21 covers the opening 231 and is connected to the case 23 to form a closed cavity in which the electrode assembly 22 is placed. The cavity may be filled with an electrolyte. In some embodiments, the end cap 21 may be provided with an electrode terminal 211, the electrode assembly 22 is provided with a tab 221, and the electrode terminal 211 may be used to electrically connect with the tab 221 for outputting electrical energy of the battery cell 20. Each of the electrode terminals 211 may be correspondingly provided with a current collecting member, which may be located between the end cap 21 and the tab 221 such that the electrode terminals 211 and the tab 221 may be electrically connected through the current collecting member. The end cap 21 may also be provided with other functional components, such as a pressure relief mechanism for relieving internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold value. The material of the housing 23 and the end cap 21 may be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

Fig. 5 is a schematic structural diagram of the battery cell 20 in fig. 4; fig. 6 is a sectional view of the battery cell 20 of fig. 5 taken along a-a; fig. 7 is a partial enlarged view of fig. 6 at B.

Referring to fig. 5, 6 and 7, after the end cap 21 is covered on the opening 231 of the housing 23, the end cap 21 and the housing 23 are welded and fixed, the housing 23 and the end cap 21 are welded to form a welded portion 24, and the welded portion 24 refers to a joint formed after the housing 23 and the end cap 21 are welded. The material of the housing 23 and the end cap 21 is not limited, but it is necessary to ensure the same material. A metal material that is lightweight and has good thermal conductivity is preferable. Such metallic materials include, but are not limited to, aluminum, stainless steel, and nickel plated steel. In the welding method of this example, the housing 23 and the end cap 21 are made of aluminum.

FIG. 8 is a schematic view of the end cap 21 of FIG. 7 prior to welding with the housing 23; fig. 9 is an exploded view of the state before the end cap 21 and the case 23 are welded in fig. 8.

In some embodiments, referring to fig. 6 to 9, the battery cell 20 includes: electrode assembly 22, case 23, and end cap 21. The case 23 is used for accommodating the electrode assembly 22, the case 23 has an opening 231 and a top end surface 232 surrounding the periphery of the opening 231; the end cap 21 is used for covering the opening 231, the end cap 21 includes a cap body 213 and a projection 212 surrounding the outer periphery of the cap body 213, the projection 212 includes an inner surface 2121 facing the electrode assembly 22 and an outer surface 2122 facing away from the electrode assembly 22, the inner surface 2121 and the outer surface 2122 are oppositely arranged in the thickness direction Z of the end cap 21, the inner surface 2121 is attached to the top end surface 232 and is formed with an abutting region 25; wherein the housing 23 is welded to the end cap 21 as a single piece and forms a weld 24 (see fig. 7), the weld 24 being configured to be formed at least in part on the butt region 25 and spaced from the outer surface 2122 in the thickness direction Z of the end cap 21 by a first predetermined distance f, which is the minimum distance in the thickness direction Z between the weld 24 and the outer surface 2122.

In some embodiments, the attachment of the inner surface 2121 to the top end surface 232 means that after the end cap 21 is fitted to the opening 231, the cap body 213 closes the opening 231, and the top end surface 232 surrounding the periphery of the opening 231 is lapped on the top end surface 232 of the housing 23, so that the inner surface 2121 of the end cap 21 is in contact with the top end surface 232; butt region 25 refers to the region where inner surface 2121 is attached to top surface 232 such that inner surface 2121 contacts top surface 232. For example, in fig. 9, when the cover body 213 and the inner circumferential surface 233 of the housing 23 are the same in size and the width of the inner surface 2121 and the thickness d of the housing 23 are exactly the same, the inner surface 2121 completely abuts against the top end surface 232 of the housing, and the entire contact area between the inner surface 2121 and the top end surface 232 is the abutting area 25.

When assembling the battery cell 20, the electrode assembly 22 is first inserted into the case 23 from the opening 231, the electrode assembly 22 is electrically connected to the electrode terminal 211 provided on the end cap 21, the end cap 21 is fitted to the opening 231, and the end cap 21 and the case 23 are welded together by welding at the butt joint region 25 where the inner surface 2121 is attached to the distal end surface 232.

During welding, welding is performed from the outer surfaces of the end cover 21 and the shell 23 to the inside of the butt joint region 25 at the position of the butt joint region 25, so that a welding part 24 is formed in the butt joint region 25, the welding part 24 is of an annular structure surrounding the battery cell 20, the end cover 21 and the shell 23 are welded integrally, and sealing of the battery cell 20 is achieved.

With continued reference to fig. 7, in some embodiments, the cross-sectional shape of the welding portion 24 gradually narrows from the outer peripheral surface 243 of the end cover 21 and the shell 23 to the inside of the abutting region 25, the welding portion 24 and the outer surface 2122 are spaced apart by a first predetermined distance f in the thickness direction Z of the end cover 21, and the first predetermined distance f is the minimum distance in the thickness direction Z between the welding portion 24 and the outer surface 2122, that is, in fig. 7, the welding portion 24 is located at the distance f between the highest point 2431 of the outer peripheral surface 243 of the shell 23 and the end cover 21 and the outer surface 2122 along the thickness direction Z.

The end of the outer surface of the welded portion 24 remote from the electrode assembly 22 is spaced from the outer surface 2122 by a first predetermined distance f in the thickness direction Z of the end cap 21 such that the welded portion 24 does not reach the outer surface 2122 in the thickness direction Z, and thus the welded portion 24 does not form a welding projection on the outer surface 2122, the appearance of the battery cell 20 does not change significantly, and the dimensional accuracy of the battery cell 20 is improved.

The end cover 21 and the shell 23 can be welded by laser welding, welding lasers are selected, and semiconductor pulse lasers, optical fiber lasers and semiconductor/optical fiber composite lasers are selected. The laser spot size is selected, the required spot radius is smaller than the thickness h of the convex body 212, the spot diameter is recommended to be less than 0.2mm, and the optical fiber laser with the spot diameter of 0.1mm is preferably selected for welding. In the actual welding process, the center of the light beam is not on the butt joint area 25 due to assembly error, positioning error and the like, so that the recommended offset is less than or equal to 0.1mm, and the first preset distance f is greater than 0. The welding can be carried out within the range of the speed of 50 mm/s-500 mm/s, and the laser is welded at a constant speed along the welding line. Of course, other welding methods may be selected according to the size and material of the battery cell 20, and the embodiment of the present application is not limited thereto.

FIG. 10 is a dimensional relationship diagram of the weld 24 of some embodiments.

In fig. 10, the dotted line is a contour line of the butt joint between the end cap 21 and the case 23 before welding, and the thick black solid line is a contour line of the welded portion 24 formed after the end cap 21 and the case 23 are welded.

As shown in fig. 10, in some embodiments, the first predetermined distance f and the thickness h of the protrusion 212 satisfy: 0.25h > f > 0.

Making the first predetermined distance f greater than 0 ensures that the fusion bond 24 remains a distance from the outer surface 2122, reduces the risk of melting of the outer surface 2122 and forming a protrusion on the outer surface 2122, and improves the dimensional accuracy of the battery cell 20. The first predetermined distance f is smaller than 0.25 times of the thickness h of the convex body 212, so that the convex body 212 has enough width to be welded with the shell 23, the width of the welding part 24 can be ensured, the welding strength is ensured, and the sealing performance is improved.

With continued reference to fig. 10, in some embodiments, the cover body 213 protrudes from the inner surface 2121 in a direction facing the electrode assembly 22; the welding portion 24 includes a first welding portion 241 for integrally connecting the protrusion 212 with the case 23 and a second welding portion 242 provided at the cover body 213.

When the end cap 21 is welded to the housing 23, the materials of the protrusion 212 and the housing 23 in the butt-joint region 25 are melted to form a first welded portion 241, and the cover body 213 is continuously melted in the extending direction from the cover body 213 to the butt-joint region 25 to form a second welded portion 242.

The fusion portion 24 extends into the cover body 213 of the end cover 21, and the first fusion portion 241 and the second fusion portion 242 are formed, so that the fusion depth of the fusion portion 24 into the end cover 21 can be ensured, and the strength of the fusion portion 24 can be improved.

With continued reference to fig. 9 and 10, in some embodiments, the cap body 213 has a circumferential side surface 2132 and a chamfered surface 2131 disposed obliquely with respect to the circumferential side surface 2132 and toward the interior of the housing 23, such that the cap body 213 extends toward the interior of the housing 23, the circumferential side surface 2132 is a side surface extending toward the interior of the housing 23 around the cap body 213 and engaging with the inner wall surface 233, the circumferential side surface 2132 is disposed to engage with the inner wall surface 233 of the housing 23, one end of the circumferential side surface 2132 is connected to the inner surface 2121, and the other end is connected to the chamfered surface 2131; the welded portion 24 and the chamfered surface 2131 are spaced apart by a second predetermined distance e in the thickness direction Z of the end cap 21, and the second predetermined distance e is the minimum distance in the thickness direction Z between the welded portion 24 and the chamfered surface 2131.

The chamfered surface 2131 is provided on the end edge of the cap body 213 facing the electrode assembly 22, and the cap body 213 can be easily fitted into the case 23 when the end cap 21 is fitted to the opening 231. In some embodiments, the height of the chamfered surface 2131 in the thickness direction Z of the end cap 21 may be set to 0.5 millimeters (mm).

When the end cap 21 and the case 23 are welded, after the welding laser penetrates the butt area 25, the first welded portion 241 is formed to have a certain width in the thickness direction Z of the end cap 21, the first welded portion 241 is formed to have a second welded portion 242 in the extending direction of the butt area 25 from the circumferential side surface 2132 of the cap body 213, since the circumferential side surface 2132 is connected to the chamfered surface 2131, a gap remains between the chamfered surface 2131 and the inner wall surface 233 of the case 23, and if the width of the first welded portion 241 in the thickness direction Z of the end cap 21 is too wide and reaches the chamfered surface 2131 beyond the circumferential side surface 2132, a welding material flows into the interior of the battery cell 20 from the gap between the chamfered surface 2131 and the inner wall surface 233, and damages the electrode assembly 22.

The welding portion 24 and the chamfered surface 2131 are arranged at a second predetermined distance e in the thickness direction Z of the end cap 21, and the second predetermined distance e is the minimum distance between the welding portion 24 and the chamfered surface 2131 in the thickness direction Z, that is, the distance between the end of the outer surface of the welding portion 24 facing the electrode assembly 22 and the end of the connection between the chamfered surface 2131 and the circumferential side 2132 in the thickness direction Z of the end cap 21, so that the welding material can be prevented from flowing into the inside of the battery cell 20 from the position of the chamfered surface 2131, the electrode assembly 22 can be prevented from being damaged to a certain extent, and the goodness of the battery cell 20 can be improved.

In some embodiments, the second predetermined distance e and the thickness b of the cover body 213 satisfy: 0.25b ≧ e > 0.

When the second predetermined distance e is greater than 0, the welded portion 24 and the chamfered surface 2131 can be kept at a certain distance, and the welding material can be prevented from flowing into the battery cell 20 from the position of the chamfered surface 2131, thereby preventing the electrode assembly 22 from being damaged. The thickness b of the lid body 213, which makes the second predetermined distance e smaller than 0.25 times, can ensure the width of the weld portion 24, ensure the welding strength, and improve the sealing performance.

With continued reference to fig. 10, in some embodiments, the first weld 241 includes a first portion 2411 and a second portion 2412 on opposite sides of the interface region 25, the first portion 2411 being closer to the outer surface 2122 than the second portion 2412, and the first portion 2411 and the second portion 2412 being symmetrically disposed relative to the interface region 25.

Welding the end cap 21 to the shell 23 from the location of the interface region 25 melts substantially the same width as the projection 212 and the shell 23, thereby enabling the first weld 241 to form substantially symmetrical first and second portions 2411, 2412 relative to the interface region 25.

The laser welding light beam center is kept with an offset of 0.1mm or less due to an assembly error, a positioning error, or the like, and, in order to ensure the dimensions of the first predetermined distance f and the second predetermined distance e, the first portion 2411 and the second portion 2412 are symmetrically disposed with respect to the butting area 25 not absolutely disposed but in a substantially symmetrical shape with respect to the butting area 25.

In some embodiments, the plane of extension of the interface region 25 passes through the top end line 2421 of the second weld 242, the top end line 2421 of the second weld 242 referring to the end line of the second weld 242 extending inwardly of the cover body 213 around the circumference of the end cover 21.

When the end cover 21 and the case 23 are welded from the position of the butt area 25, the weld portion 24 is formed symmetrically with respect to the butt area 25, the width of the projection 212 and the case 23 melted is made the same, and the welding is continued to the inside of the cover body 213, the second weld portion 242 is formed, and the extension plane of the butt area 25 passes through the tip end line 2421 of the second weld portion 242, so that the weld portion 24 as a whole can be formed symmetrically with respect to the butt area 25.

In some embodiments, the maximum depth c of the fusion splice 24 in the first direction R and the thickness d of the shell 23 satisfy: c-d is greater than or equal to 100 micrometers (mum), wherein the first direction R is the direction of the convex body 212 pointing to the cover body 213, that is, the distance of the welding part 24 exceeding the inner wall surface 233 of the shell 23 along the first direction R is greater than or equal to 100 μm, for example, the c-d is greater than or equal to 120 μm, 150 μm or 200 μm.

For a cylindrical battery cell, the first direction R is the radial direction of the battery cell 20; for a prismatic cell, the first direction R is the longitudinal direction X of the cell 20 at the welded portion 24 on the wide side of the cell 20, the first direction R is the width direction Y of the cell 20 at the welded portion 24 on the long side of the cell 20. The depth of the weld 24 extending into the end cap 21, i.e., the maximum depth c in the first direction R, is greater than the thickness d of the case 23 and extends into the cap body 213 a distance greater than 100 μm. As shown in fig. 10, the depth of the second fusion-bonded portion 242 in the first direction R is 100 μm or more, so that the depth of the fusion-bonded portion 24 can be secured, the strength of the fusion-bonded portion 24 can be increased, and the sealing performance of the battery cell 20 can be improved.

In some embodiments, the maximum width a of the weld 24 in the thickness direction Z, the lid body thickness b, the first predetermined distance f, and the second predetermined distance e satisfy: a/b is more than or equal to 0.5 and less than 1, and f + a + e is more than or equal to b.

The maximum width a of the weld 24 in the thickness direction Z refers to the width of the widest position of the weld 24, and in some embodiments, since the cross-sectional shape of the weld 24 gradually narrows from the width of the end cover 21 and the outer peripheral surface 243 of the housing 23 toward the inside of the butt area 25, the maximum width a is the width of the weld 24 between the highest point 2431 and the lowest point 2432 of the outer peripheral surface 243 of the housing 23 and the end cover 21 in fig. 10.

Making the maximum width a of the welded portion 24 in the thickness direction Z smaller than the cover body thickness b and equal to or greater than 0.5 times the cover body thickness b enables the strength of the welded portion 24 to be ensured, and in order to avoid forming a protrusion on the outer surface 2122 and to avoid the welding material from flowing into the inside of the battery cell 20, the sum of the first predetermined distance f, the maximum width a of the welded portion 24, and the second predetermined distance e should be smaller than the cover body thickness b.

In some embodiments, the thickness h of the projection 212 is greater than the thickness d of the housing 23.

The protrusion 212 is overlapped on the housing 23, the first inner surface 2121 of the protrusion 212 abuts against the top end surface 232 of the housing 23 to form an abutting region 25, all the weight of the end cap 21 is borne on the protrusion 212, the thickness h of the protrusion 212 is made larger than the thickness d of the housing 23, the width of the welded portion 24 can be ensured, the strength of the protrusion 212 can be ensured, and the end cap 21 is not deformed when the end cap 21 bears the pressure in the thickness direction Z or the end cap 21 is fixedly mounted.

In some embodiments, the thickness h of the protrusion 212 and the thickness b of the cover body 213 satisfy: h is more than or equal to 0.5b and more than or equal to 0.5 millimeter (mm). The thickness h of the projection 212 is greater than 0.5mm, which ensures the strength of the projection 212, and the first predetermined distance f between the end of the outer surface of the welded portion 24 away from the electrode assembly 22 and the outer surface 2122 is maintained, while ensuring the width of the welded portion 24 and the strength of the weld, ensuring that no protrusion is formed on the outer surface 2122.

In some embodiments, the thickness b of the cover body 213 satisfies: b is more than or equal to 1.5mm and more than or equal to 2.5 mm. The thickness b of the cover body 213 is between 2.5mm and 1.5mm, which can ensure the strength of the cover body 213, ensure the cover body 213 to have enough width to form the welding part 24, ensure the welding strength of the welding part 24, and meet the requirement of the welding process.

In some embodiments, the thickness d of the housing 23 is ≧ 0.2 mm. The thickness d of the housing 23 is set to meet the strength requirement of the housing 23, and the welding strength requirement when the housing 23 is welded to the end cover 21 can be met.

While the application has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the application. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. The present application is not intended to be limited to the particular embodiments disclosed herein but is to cover all embodiments that may fall within the scope of the appended claims.

Claims (15)

1. A battery cell, comprising:

an electrode assembly;

a case for accommodating the electrode assembly, the case having an opening and a top end surface surrounding an outer periphery of the opening;

an end cap for covering the opening, the end cap including a cap body and a protrusion surrounding an outer periphery of the cap body, the protrusion including an inner surface facing the electrode assembly and an outer surface facing away from the electrode assembly, the inner surface and the outer surface being oppositely disposed in a thickness direction of the end cap, the inner surface being attached to the top end surface and formed with a butt joint region;

wherein the shell and the end cap are welded together to form a weld, the weld being configured to be formed at least in part on the butt-joint region and spaced apart from the outer surface in the thickness direction by a first predetermined distance, the first predetermined distance being a minimum distance of the weld from the outer surface in the thickness direction.

2. The battery cell as recited in claim 1, wherein the first predetermined distance f and the thickness h of the protrusion satisfy: 0.25h > f > 0.

3. The battery cell of claim 1, wherein the cover body protrudes from the inner surface in a direction facing the electrode assembly;

the welding part comprises a first welding part and a second welding part, the first welding part is used for connecting the bulge body and the shell body into a whole, and the second welding part is arranged on the cover body.

4. The battery cell according to claim 3, wherein the cap body has a peripheral side surface and a chamfered surface provided obliquely to the peripheral side surface and toward the inside of the case, the peripheral side surface is provided to fit an inner wall surface of the case, one end of the peripheral side surface is connected to the inner surface, and the other end is connected to the chamfered surface;

and a second preset distance is formed between the welding part and the chamfered surface in the thickness direction, and the second preset distance is the minimum distance between the welding part and the chamfered surface in the thickness direction.

5. The battery cell as recited in claim 4, wherein the second predetermined distance e and the thickness b of the cover body satisfy: 0.25b ≧ e > 0.

6. The battery cell as recited in claim 3 wherein the first weld includes a first portion and a second portion on either side of the interface region, the first portion being closer to the outer surface than the second portion, the first portion and the second portion being symmetrically disposed relative to the interface region.

7. The battery cell as recited in claim 6 wherein the plane of extension of the interface region passes through the tip line of the second weld.

8. The battery cell according to claim 1, wherein a maximum depth c of the welded portion in the first direction and a thickness d of the case satisfy: c-d is more than or equal to 100 mu m, wherein the first direction is the direction of the convex body pointing to the cover body.

9. The battery cell according to claim 4 or 5, wherein a maximum width a of the welded portion in the thickness direction, the cover body thickness b, the first predetermined distance f, and the second predetermined distance e satisfy: a/b is more than or equal to 0.5 and less than 1, and f + a + e is more than or equal to b.

10. The battery cell of any of claims 1-8, wherein the thickness h of the protrusion is greater than the thickness d of the housing.

11. The battery cell as recited in claim 9, wherein the thickness h of the protrusion and the thickness b of the cover body satisfy: h is more than or equal to 0.5b and more than or equal to 0.5 mm.

12. The battery cell according to any one of claims 1 to 8, wherein the thickness b of the cover body satisfies: b is more than or equal to 1.5mm and more than or equal to 2.5 mm.

13. The battery cell according to any one of claims 1 to 8, wherein the thickness d of the casing is 0.2mm or more.

14. A battery comprising a plurality of cells according to any one of claims 1 to 13.

15. An electrical device comprising a battery according to claim 14 for providing electrical energy.

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