Battery monomer, battery and electric device

Abstract

The utility model is applicable to the technical field of power batteries, and provides a single battery, a battery and a power utilization device. The electrode assembly is accommodated in the accommodating cavity and comprises a flat part and a bent part connected with the flat part; the buffering piece is contained in the containing cavity and comprises a first part and a second part connected to the first part. The first part is opposite to the bent part, the first part comprises a first surface opposite to the bent part, and the first surface is an arc-shaped surface with the same bending direction as the side surface of the bent part; the second part is opposite to the flat part, and in the arrangement direction of the flat part and the bent part, the thickness of the second part is gradually increased from the middle of the flat part to the edge of the flat part; according to the battery monomer provided by the embodiment of the invention, the difference of expansion deformation quantity of the flat part and the bent part can be reduced, so that the phenomenon of stress concentration is reduced, and the risk of breakage of the electrode assembly is reduced.

Description

Technical Field

[0001] This application belongs to the technical field of power batteries, and particularly relates to a battery cell, a battery and an electrical device. Background Art

[0002] Energy conservation and emission reduction are the keys to the sustainable development of the automotive industry. Electric vehicles have become an important part of the sustainable development of the automotive industry due to their advantages of energy conservation and environmental protection. For electric vehicles, battery technology is an important factor related to their development.

[0003] During the use of the battery, the active layer of the electrode sheet in the electrode assembly is prone to expansion; affected by the winding structure of the electrode assembly, during the expansion and deformation of the electrode sheet, the deformation amounts at different positions of the electrode assembly are not the same, which may cause stress concentration on the electrode sheet. As the electrode assembly gradually ages, the electrode sheet is prone to cracking in the stress concentration area, thus having a negative impact on the safety performance and service life of the battery. Utility Model Content

[0004] In view of the above problems, this application provides a battery cell, a battery and an electrical device, which can alleviate the problem of stress concentration caused by electrode sheet expansion.

[0005] In a first aspect, an embodiment of this application provides a battery cell, including: a housing having a receiving cavity therein; an electrode assembly received in the receiving cavity, the electrode assembly including a flat portion and a bent portion connected to the flat portion; a buffer member received in the receiving cavity and located between the electrode assembly and the housing, the buffer member including a first portion and a second portion connected to the first portion; the first portion is opposite to the bent portion, the first portion includes a first surface opposite to the bent portion, and the first surface is an arc surface whose bending direction is the same as the bending direction of the side surface of the bent portion; the second portion is opposite to the flat portion, and in the arrangement direction of the flat portion and the bent portion, the thickness of the second portion gradually increases from the middle of the flat portion to the edge of the flat portion, so that the surface of the second portion facing the flat portion gradually approaches the corresponding flat portion.

[0006] In the technical solution of this embodiment, a buffer member is provided in the housing, the first portion of the buffer member is opposite to the bent portion, and the first surface of the first portion is an arc surface. In the case of expansion of the electrode assembly, this setting can increase the contact area between the bent portion and the first surface, thereby alleviating the stress concentration; the second portion of the buffer member is opposite to the flat portion, and the thickness of the second portion gradually increases from the middle of the flat portion to the edge of the flat portion. This setting can not only enable the flat portion to have a larger expansion space at the position where the thickness of the second portion is smaller, thereby reducing the difference in expansion deformation amounts between the flat portion and the bent portion, but also enable the buffer member to be closer to the electrode assembly at the position where the flat portion and the bent portion are connected, so as to inhibit the expansion deformation amount at this position, thereby alleviating the situation that the connection between the bent portion and the flat portion is prone to breakage due to the difference in expansion deformation amounts.

[0007] In some embodiments, the bent portion is attached to and abuts against the first surface.

[0008] In the technical solution of this embodiment, the bent portion is attached to the first surface to increase the contact area between the bent portion and the first portion, thereby alleviating the problem of stress concentration in the bent portion; the bent portion abuts against the first surface to better suppress the expansion deformation amount of the bent portion through the first portion, reducing the difference in the expansion deformation amounts between the bent portion and the flat portion, thereby alleviating the problem of stress concentration at the connection position between the bent portion and the flat portion of the electrode assembly and reducing the occurrence of electrode assembly fracture.

[0009] In some embodiments, the first portion and the second portion are sequentially and alternately connected end to end to enclose an inner space for accommodating the electrode assembly; there is a first difference between the maximum length of the inner space and the maximum length of the electrode assembly, and there is a second difference between the maximum width of the inner space and the maximum width of the electrode assembly, and the first difference is less than or equal to the second difference.

[0010] The technical solution of this embodiment provides a size range for some buffer members so that the expansion deformation space of the bent portion is smaller than that of the flat portion, reducing the difference in the expansion deformation amounts between the bent portion and the flat portion, thereby alleviating the problem of stress concentration at the connection position between the bent portion and the flat portion of the electrode assembly and reducing the occurrence of electrode assembly fracture.

[0011] In some embodiments, the range of the first difference is 0 to 2 mm.

[0012] The technical solution of this embodiment provides a range of the difference between the length of the inner space and the length of the electrode assembly so that the expansion deformation space of the bent portion is smaller, thereby being able to reduce the difference in the expansion deformation amounts between the bent portion and the flat portion.

[0013] In some embodiments, the range of the first difference is 0 to 1 mm.

[0014] The technical solution of this embodiment further provides a range of the difference between the length of the inner space and the length of the electrode assembly to better suppress the expansion deformation of the bent portion and better reduce the difference in the expansion deformation amounts between the bent portion and the flat portion.

[0015] In some embodiments, the minimum value of the second difference is 0.5 times the difference between the width of the accommodation cavity and the width of the electrode assembly, and the maximum value of the second difference is the difference between the width of the accommodation cavity and the width of the electrode assembly.

[0016] The technical solution of this embodiment provides a range of the difference between the width of the inner space and the width of the electrode assembly, so that the flat part has a large expansion deformation space, thereby reducing the difference in the expansion deformation amount between the bent part and the flat part, and also enabling more expansion force of the electrode assembly to be released at the flat part, thereby reducing the harm caused by the expansion of the electrode assembly.

[0017] In some embodiments, the minimum value of the second difference is greater than or equal to 2 mm.

[0018] The technical solution of this embodiment provides a range of the difference between the width of the inner space and the width of the electrode assembly, so that the flat part has a large expansion deformation space, reducing the difference in the expansion deformation amount between the bent part and the flat part, and also facilitating the release of the expansion force of the electrode assembly.

[0019] In some embodiments, the buffer member abuts against the connecting portion between the bent part and the flat part at the connecting position of the first part and the second part.

[0020] In the technical solution of this embodiment, the buffer member can abut against the connecting portion between the bent part and the flat part to squeeze the electrode assembly at this portion, suppressing the expansion deformation amount of the electrode assembly at this portion, thereby reducing the risk of the electrode assembly breaking at this position.

[0021] In some embodiments, in the width direction of the electrode assembly, the range of the difference between the size of the inner space at the connecting position of the first part and the second part and the width of the electrode assembly is 0 to 1 mm.

[0022] In the technical solution of this embodiment, the buffer member is relatively close to the connecting portion between the bent part and the flat part of the electrode assembly to suppress the expansion deformation amount of the electrode assembly at this portion, thereby reducing the risk of the electrode assembly breaking at this position.

[0023] In some embodiments, the second part includes a second surface facing the flat part. The second surface is connected to the first surface and forms a connecting portion at the connecting position. From the connecting portion to the middle of the first surface, the distance between the first surface and the bent part remains unchanged or gradually increases. In the direction pointing from the connecting portion to the second surface, the distance between the second surface and the flat part gradually increases.

[0024] In the technical solution of this embodiment, the distance between the buffer member and the connecting portion between the flat part and the bent part is small, and at the same time, the flat part and the bent part have a deformation space, so that the buffer member can not only suppress the expansion deformation of the electrode assembly at the connecting portion between the flat part and the bent part, but also release the expansion force of the electrode assembly.

[0025] In some embodiments, the maximum value of the distance between the second surface and the flat part is greater than or equal to the maximum value of the distance between the first surface and the bent part.

[0026] The technical solution of this embodiment can make the expansion deformation space of the bending part smaller than that of the flat part, so as to reduce the difference in the expansion deformation amount between the bending part and the flat part, thereby alleviating the problem of stress concentration at the connection position between the bending part and the flat part of the electrode assembly and reducing the occurrence of electrode assembly fracture.

[0027] In some embodiments, the height of the buffer is less than or equal to the height of the electrode assembly.

[0028] In the technical solution of this embodiment, the height of the buffer is made less than or equal to the height of the electrode assembly, so that the buffer can not only inhibit the expansion deformation of the bending part, but also reduce the space occupied by the buffer.

[0029] In some embodiments, the range of the difference between the height of the electrode assembly and the height of the buffer is 0-5 mm.

[0030] The technical solution of this embodiment provides a range of differences in height between the buffer and the electrode assembly. In the case of the expansion of the electrode assembly, this setting can reduce the stress concentration at the edge of the electrode assembly in the height direction of the buffer.

[0031] In some embodiments, the height of the buffer is greater than or equal to the height of the electrode assembly.

[0032] In the technical solution of this embodiment, the height of the buffer is made greater than the height of the electrode assembly, so that the buffer can also be used to separate the electrode assembly from the end cover of the battery cell. At this time, an insulating part may not be provided on the side of the end cover facing the electrode assembly, thereby reducing the number of internal components of the battery cell and the processing difficulty.

[0033] In some embodiments, the range of the difference between the height of the buffer and the height of the electrode assembly is 0-10 mm.

[0034] The technical solution of this embodiment provides a range of differences in height between the buffer and the electrode assembly, so that the buffer can not only limit the expansion deformation amount of the electrode assembly, but also separate the electrode assembly from the end cover.

[0035] In some embodiments, the range of the difference between the height of the buffer and the height of the electrode assembly is 3-10 mm.

[0036] The technical solution of this embodiment further provides a range of differences in height between the buffer and the electrode assembly, so that the buffer can better separate the electrode assembly from the end cover and reduce the short circuit between the electrode assembly and the end cover.

[0037] In some embodiments, the buffer abuts against the housing.

[0038] In the technical solution of this embodiment, the buffer member is abutted against the inner wall of the housing, so as to facilitate fixing the buffer member in the housing and also facilitate the housing to provide support for the buffer member, so that the buffer member can better exert a force on the electrode assembly to limit the expansion deformation of the electrode assembly.

[0039] In some embodiments, the buffer member is spaced from the housing, and the spacing range between the buffer member and the housing is 0 to 0.5 mm.

[0040] The technical solution of this embodiment provides some gap sizes between the buffer member and the inner wall of the housing, so that there is a gap between the buffer member and the inner wall of the housing to reduce the assembly difficulty of the buffer member.

[0041] In some embodiments, the number of electrode assemblies is at least two, and the electrode assemblies are arranged along the width direction of the battery cell, and two adjacent flat portions are in contact with each other; the first portion includes at least two first surfaces arranged along the width direction of the battery cell, and each first surface is opposite to an adjacent bending portion.

[0042] In the technical solution of this embodiment, the battery cell includes at least two electrode assemblies, and the first portion includes at least two first surfaces, and each first surface is opposite to an adjacent bending portion, so that each first surface can respectively limit the expansion of each bending portion, thereby better limiting the expansion of the bending portion and reducing the force exerted by the expansion of the bending portion on the adjacent electrode assembly.

[0043] In some embodiments, a partition groove is provided on the second portion, and the partition groove is used to partition the second portion into two sub-portions spaced along the length direction of the battery cell.

[0044] In the technical solution of this embodiment, the partition groove is provided to partition the second portion into two sub-portions, so that the flat portion can have a larger expansion deformation space; at the same time, this setting can also reduce the occupation of the accommodation cavity space by the buffer member.

[0045] In some embodiments, a chamfer is provided on the edge of one of the two sub-portions facing the other.

[0046] In the technical solution of this embodiment, a chamfer is provided on the edge of the sub-portion. In the case of the expansion of the electrode assembly, this setting can relieve the stress concentration phenomenon of the electrode assembly at the edge of the sub-portion.

[0047] In some embodiments, the buffer member is an elastic member.

[0048] In the technical solution of this embodiment, the buffer member is an elastic member. In the case of the expansion of the electrode assembly, this setting can provide an expansion space for the electrode assembly to facilitate the release of the expansion force of the electrode assembly.

[0049] In some embodiments, the compression ratio range of the buffer is 0 to 70%.

[0050] The technical solution of this embodiment provides a compression ratio range of some buffers, so that the buffer can not only provide space for the expansion of the electrode assembly, but also limit the expansion deformation amount of the electrode assembly.

[0051] In some embodiments, the compression ratio range of the buffer is 30% to 50%.

[0052] The technical solution of this embodiment further provides a compression ratio range of some buffers, so that the buffer can not only provide space for the expansion of the electrode assembly, but also better limit the expansion deformation amount of the electrode assembly.

[0053] In some embodiments, the buffer further includes a third part connected to the first part and the second part, and the third part is used to support the electrode assembly.

[0054] In the technical solution of this embodiment, the buffer includes a third part, so as to separate the electrode assembly from the housing through the third part, thereby reducing the short-circuit situation caused by the contact between the electrode assembly and the housing; at the same time, this setting can also save the bottom plate in the battery cell, thereby reducing the number of components of the electrode assembly and reducing the processing difficulty of the battery cell.

[0055] In some embodiments, through holes are formed in the third part.

[0056] In the technical solution of this embodiment, through holes are provided in the third part to facilitate the electrolyte to flow through the third part and better wet the electrode assembly.

[0057] In a second aspect, some embodiments of the present application further provide a battery, including the battery cell provided in some embodiments of the first aspect.

[0058] In a third aspect, some embodiments of the present application further provide an electrical device, including the battery provided in some embodiments of the second aspect.

[0059] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically listed below. Description of the Drawings

[0060] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. And in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0061] Figure 1 Schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0062] Figure 2 Explosion structural diagram of a battery provided in some embodiments of the present application;

[0063] Figure 3 Explosion structural diagram of a battery cell provided in some embodiments of the present application;

[0064] Figure 4 Top - view structural schematic of a battery cell after removing the end - cover provided in some embodiments of the present application Figure 1 ;

[0065] Figure 5 Top - view structural schematic of a battery cell after removing the end - cover provided in some embodiments of the present application Figure 2 ;

[0066] Figure 6 Top - view structural schematic of a battery cell after removing the end - cover provided in some embodiments of the present application Figure 3 ;

[0067] Figure 7 is Figure 4 Local enlarged schematic diagram at position A in

[0068] Figure 8 Schematic structural diagram of a buffer member and an electrode assembly in a battery cell provided in some other embodiments of the present application;

[0069] Figure 9 Schematic structural diagram of a buffer member and an electrode assembly in a battery cell provided in some other embodiments of the present application;

[0070] Figure 10 Top - view schematic diagram of a buffer member provided in some embodiments of the present application;

[0071] Figure 11 Three - dimensional schematic diagram of a buffer member provided in some embodiments of the present application.

[0072] The meanings of the marks in the figure are as follows:

[0073] 1000, vehicle;

[0074] 100, battery;

[0075] 10, box body; 11, upper box body; 12, lower box body;

[0076] 20. Battery cell; 21. Housing; 211. Accommodation cavity; 22. Electrode assembly; 221. Flat portion; 222. Bent portion; 23. End cap; 24. Electrode terminal; 25. Buffer member; 251. First part; 2511. First surface; 252. Second part; 2521. Second surface; 2522. Partition groove; 2523. Sub - part; 253. Inner space; 254. Connection part; 255. Third part; 2551. Through - hole

[0077] 200. Motor

[0078] 300. Controller Detailed implementation mode

[0079] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, so they are only examples and cannot be used to limit the protection scope of the present application.

[0080] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description of the specification, claims and drawings of this application are intended to cover non - exclusive inclusion.

[0081] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary - secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means two or more unless otherwise specifically defined.

[0082] Referring to "embodiment" herein means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of this application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0083] In the description of the embodiments of this application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0084] In the description of the embodiments of the present application, the term "plurality" means two or more (including two). Similarly, "multiple groups" means two or more groups (including two groups), and "multiple pieces" means two or more pieces (including two pieces).

[0085] In the description of the embodiments of the present application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of the present application.

[0086] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0087] Currently, from the perspective of the development of the market situation, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as military equipment and aerospace. With the continuous expansion of the application fields of power batteries, the market demand is also continuously increasing.

[0088] During the use of the electrode assembly, the active layer on the electrode sheet of the electrode assembly is prone to swelling. For a battery with a square case, due to the influence of the winding structure characteristics of the electrode assembly, when the flat part of the electrode assembly swells to abut against the case, it will be restricted by the case and unable to further swell and deform. At this time, there is still space between the bent part of the electrode assembly and the case. That is, when the flat part cannot continue to swell and deform, the bent part can still further swell and deform. This will result in inconsistent swelling deformation amounts of the flat part and the bent part of the electrode assembly, and it is easy to cause stress concentration at the intersection of the bent part and the flat part. This stress will gradually accumulate on the outermost electrode sheet of the electrode assembly and will form a relatively obvious boundary (i.e., the stress concentration site) between the bent part and the flat part. As the electrode assembly gradually swells and deforms, the gap in the swelling deformation amounts between the bent part and the flat part will become larger and larger, the stress concentration phenomenon will become more and more serious, and the risk of electrode sheet fracture will become higher and higher.

[0089] Moreover, the bent part of the electrode assembly is mostly arc-shaped. When the electrode assembly swells and the bent part abuts against the case, the contact area between the bent part and the case is small, and even a situation of approximate line contact may occur. This is likely to cause stress concentration at the contact position between the bent part and the case and is likely to cause electrode sheet fracture.

[0090] In order to alleviate the problem of stress concentration caused by the swelling of the electrode sheet, the present application provides a battery cell. A buffer member is provided between the case and the electrode assembly. The buffer member includes a first part and a second part. The first part faces the bent part, the second part faces the flat part, and the first surface of the first part facing the bent part is an arc surface. At the same time, in the arrangement direction of the flat part and the bent part, the thickness of the second part gradually increases from the middle of the flat part to the edge of the flat part, so that the flat part has a larger swelling space at the position where the thickness of the second part is smaller.

[0091] In such a battery cell, the arc-shaped first surface can increase the contact area between the bent part and the first surface when the electrode assembly swells, so as to alleviate the stress concentration situation, thereby reducing the risk of fracture of the electrode sheet at the contact position between the bent part and the first surface. The thickness of the flat part gradually increases from the middle of the flat part to the edge of the flat part, so that the flat part has a larger swelling deformation space at the position where the thickness of the second part is smaller, reducing the difference between the swelling deformation amount of the bent part and the swelling deformation amount of the flat part, and enabling the swelling force of the electrode assembly to be released to the flat part. Thereby, the swelling force on the bent part can be reduced, the problem that the connection part between the bent part and the flat part is prone to fracture can be alleviated, and the stress concentration situation of the bent part can also be alleviated.

[0092] The battery cells disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. Electrical devices can include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, battery-powered vehicles, electric vehicles, ships, spacecraft, and the like. Electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, among others.

[0093] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0094] Refer to Figure 1, Figure 1 A schematic structural diagram of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000. The battery 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000. For example, the battery 100 may serve as an operating power source for the vehicle 1000. The vehicle 1000 may further include a controller 300 and a motor 200. The controller 300 is used to control the battery 100 to power the motor 200, for example, for starting, navigating and operating power requirements of the vehicle 1000 during driving.

[0095] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0096] refer to Figure 2 , Figure 2Exploded view of the battery 100 provided in some embodiments of the present application. The battery 100 includes a box body 10 and battery cells 20, and the battery cells 20 are accommodated in the box body 10. Among them, the box body 10 is used to provide an accommodation space for the battery cells 20, and the box body 10 can adopt various structures. In some embodiments, the box body 10 may include an upper box body 11 and a lower box body 12, the upper box body 11 and the lower box body 12 cover each other, and the upper box body 11 and the lower box body 12 jointly define an accommodation space for accommodating the battery cells 20. The lower box body 12 may be a hollow structure with one end open, the upper box body 11 may be a plate-like structure, and the upper box body 11 covers the open side of the lower box body 12 so that the upper box body 11 and the lower box body 12 jointly define an accommodation space; the upper box body 11 and the lower box body 12 may also both be hollow structures with one side open, and the open side of the upper box body 11 covers the open side of the lower box body 12. Of course, the box body 10 formed by the upper box body 11 and the lower box body 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0097] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 can be connected in series, in parallel, or in a mixed connection. A mixed connection means that there are both series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed connection together, and then the whole formed by the multiple battery cells 20 is accommodated in the box body 10; of course, the battery 100 can also be that multiple battery cells 20 are first connected in series, in parallel, or in a mixed connection to form a battery 100 module form, and then multiple battery 100 modules are connected in series, in parallel, or in a mixed connection to form a whole and are accommodated in the box body 10. The battery 100 may further include other structures. For example, the battery 100 may further include a busbar component for realizing the electrical connection between the multiple battery cells 20.

[0098] Among them, each battery cell 20 can be a secondary battery cell or a primary battery cell; it can also be a lithium-sulfur battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, but is not limited thereto. The battery cell 20 can be in the shape of a cylinder, a flat body, a cuboid, or other shapes, etc.

[0099] Reference Figure 3 , Figure 3 Schematic exploded view of the battery cell 20 provided in some embodiments of the present application. The battery cell 20 refers to the smallest unit that makes up the battery 100. As shown in the figure, the battery cell 20 includes an end cap 23, a housing 21, an electrode assembly 22, and other functional components.

[0100] The end cap 23 refers to a component that covers the opening of the housing 21 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 23 can be adapted to the shape of the housing 21 to cooperate with the housing 21. Optionally, the end cap 23 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 23 is not easily deformed when subjected to extrusion and collision, enabling the battery cell 20 to have higher structural strength and improved safety performance. Functional components such as electrode terminals 24 can be provided on the end cap 23. The electrode terminals 24 can be used for electrical connection with the electrode assembly 22 to output or input the electrical energy of the battery cell 20. In some embodiments, a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold can also be provided on the end cap 23. The material of the end cap 23 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special restrictions on this. In some embodiments, an insulating member can also be provided on the inner side of the end cap 23, and the insulating member can be used to isolate the electrical connection part 254 in the housing 21 from the end cap 23 to reduce the risk of short circuit. Exemplarily, the insulating member can be plastic, rubber, etc.

[0101] The housing 21 is a component used to cooperate with the end cap 23 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 22, the electrolyte, and other components. The housing 21 and the end cap 23 can be independent components. An opening can be provided on the housing 21, and the end cap 23 is covered on the opening to form the internal environment of the battery cell 20. Without limitation, the end cap 23 and the housing 21 can also be integrated. Specifically, the end cap 23 and the housing 21 can first form a common connection surface before other components are inserted into the housing, and when it is necessary to encapsulate the inside of the housing 21, the end cap 23 is then covered on the housing 21. The housing 21 can have various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 21 can be determined according to the specific shape and size of the electrode assembly 22. The material of the housing 21 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special restrictions on this.

[0102] The electrode assembly 22 is a component in the battery cell 20 where an electrochemical reaction occurs. The housing 21 can contain one or more electrode assemblies 22. The electrode assembly 22 is mainly formed by winding or laminating a positive electrode sheet and a negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The portions of the positive electrode sheet and the negative electrode sheet having active materials constitute the main body of the electrode assembly 22, and the portions of the positive electrode sheet and the negative electrode sheet without active materials respectively constitute the electrode tabs. The positive electrode tab and the negative electrode tab can be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery 100, the positive active material and the negative active material react with the electrolyte, and the electrode tabs are connected to the electrode terminals 24 to form a current loop.

[0103] In a first aspect, referring to Figures 3 to 6 , some embodiments of the present application provide a battery cell 20, including a housing 21, an electrode assembly 22, and a buffer member 25. Among them, a receiving cavity 211 is provided in the housing 21; the electrode assembly 22 is received in the receiving cavity 211, and the electrode assembly 22 includes a flat portion 221 and a bent portion 222 connected to the flat portion 221; the buffer member 25 is received in the receiving cavity 211 and is located between the electrode assembly 22 and the housing 21, and the buffer member 25 includes a first portion 251 and a second portion 252 connected to the first portion 251; the first portion 251 faces the bent portion 222, and the first portion 251 includes a first surface 2511 facing the bent portion 222, and the first surface 2511 is an arc surface whose bending direction is the same as the bending direction of the side surface of the bent portion 222; the second portion 252 faces the flat portion 221, and in the direction from the flat portion 221 to the bent portion 222, the thickness of the second portion 252 gradually increases from the middle of the housing 21 to the edge of the housing 21, so that the surface of the second portion 252 facing the flat portion 221 gradually approaches the corresponding flat portion 221.

[0104] In the figure, the direction of the X-axis is the length direction of the battery cell 20, the direction of the Y-axis is the width direction of the battery cell 20, and the direction of the Z-axis is the height direction of the battery cell 20.

[0105] The receiving cavity 211 refers to the space in the housing 21 for receiving the battery cell 20. The receiving cavity 211 can be used to receive the electrode assembly 22, and can also be used to receive the electrolyte or other structures of the battery cell 20; the receiving cavity 211 can be a cuboid space, a cylindrical space or a space of other shapes, and the shape of the receiving cavity 211 can also be set according to the shape of the housing 21.

[0106] The flat part 221 refers to the flat portion in the electrode assembly 22, and the bent part 222 refers to the bent portion in the electrode assembly 22. The bent parts 222 are located on opposite sides of the electrode assembly 22. The positive electrode sheet, negative electrode sheet, and separator are bent during winding to form the bent parts 222. The area of the flat part 221 can be larger than the area of the bent part 222.

[0107] Exemplarily, the flat part 221 can be parallel to the plane where the length direction X and height direction Z of the battery cell 20 are located. The bent parts 222 can be located on opposite sides of the flat part 221 along the length direction X of the battery cell 20, that is, the flat part 221 and the bent parts 222 can be arranged along the length direction X of the battery cell 20.

[0108] The buffer member 25 refers to the structure in the battery cell 20 for restricting the expansion and deformation of the electrode assembly 22. The buffer member 25 can be a block structure, or can be a frame structure, a plate structure or other structures. The buffer member 25 can be a rigid structural member. For example, the material of the buffer member 25 can include metals, alloys or other materials. The buffer member 25 can also be an elastic structural member. For example, the material of the buffer member 25 can include rubber, elastic fibers or other materials.

[0109] The buffer member 25 is received in the receiving cavity 211, and the buffer member 25 is located between the electrode assembly 22 and the side wall of the housing 21, that is, the buffer member 25 is opposite to the peripheral side of the electrode assembly 22. The buffer member 25 can only cover a part of the peripheral side of the electrode assembly 22, and the buffer member 25 can also completely cover the peripheral side of the electrode assembly 22. Since the expansion and deformation of the electrode assembly 22 mainly occur in its length direction and width direction, the buffer member 25 is arranged between the electrode assembly 22 and the side wall of the housing 21, so that the buffer member 25 can not only restrict the expansion and deformation of the electrode assembly 22, but also reduce the occupation of the space of the receiving cavity 211.

[0110] The first part 251 refers to a partial structure of the buffer member 25 opposite to the bent part 222. The shape of the first part 251 can be a prism shape, a plate shape or other shapes. The material of the first part 251 can include metals, and the material of the first part 251 can also include rubber, elastic fibers or other materials.

[0111] The first part 251 faces the bent part 222, that is, the first part 251 is used to limit the expansion deformation amount of the bent part 222; the first part 251 can be arranged at an interval from the bent part 222, that is, when the battery cell 20 is in the natural state of not being used, there can be a gap between the first part 251 and the bent part 222, and this gap is used to provide space for the expansion deformation of the bent part 222, so that the bent part 222 can release part of the expansion force when the battery cell 20 expands; the first part 251 can also be in contact with or abut against the bent part 222. In the case of the expansion of the battery cell 20, this setting can better inhibit the expansion deformation of the bent part 222, so as to better reduce the difference in the expansion deformation amount between the bent part 222 and the flat part 221.

[0112] Exemplarily, when the bent parts 222 are located on both sides of the electrode assembly 22 along the length direction X of the battery cell 20, the first parts 251 are also located on both sides of the buffer member 25 along the length direction X of the battery cell 20.

[0113] The first surface 2511 refers to the surface of the first part 251 facing the bent part 222, and the first surface 2511 is an arc surface whose bending direction is the same as the bending direction of the side surface of the bent part 222; the distance between the first surface 2511 and the side surface of the bent part 222 can be equal or unequal; the radian of the first surface 2511 and the bent part 222 can be equal or unequal; in the case of the expansion of the battery cell 20, compared with the case where the first surface 2511 is a plane, making the first surface 2511 an arc surface can increase the contact area between the bent part 222 and the first surface 2511, so as to increase the force-bearing area of the reaction force of the first part 251 acting on the bent part 222, thereby being able to relieve the stress concentration situation, reduce the force locally received by the bent part 222, and reduce the situation where the electrode assembly 22 breaks at the contact position between the bent part 222 and the first part 251.

[0114] The second part 252 refers to the partial structure of the buffer member 25 opposite to the flat part 221; the shape of the second part 252 can be prismatic, plate-shaped or other shapes; the material of the second part 252 can include metal, and the material of the second part 252 can also include rubber, elastic fiber or other materials.

[0115] The second part 252 faces the flat part 221, that is, the second part 252 is used to limit the expansion deformation amount of the flat part 221; the second part 252 can be arranged at an interval from the flat part 221. When the battery cell 20 is in an unused natural state, there is a gap between the second wall and the flat part 221, and this gap is used to provide space for the expansion deformation of the flat part 221, so that the flat part 221 can release part of the expansion force when the battery cell 20 expands; the second part 252 can also be in contact with or abut against the flat part 221. In the case where the battery cell 20 expands, this setting can inhibit the expansion deformation of the flat part 221.

[0116] In the arrangement direction of the flat part 221 and the bending part 222, the thickness of the second part 252 gradually increases from the middle of the flat part 221 to the edge of the flat part 221, so that the surface of the second part 252 facing the flat part 221 gradually approaches the flat part 221; when the bending part 222 is located on both sides of the flat part 221 along the length direction X of the battery cell 20, that is, when the arrangement direction of the flat part 221 and the bending part 222 is parallel or substantially parallel to the length direction X of the battery cell 20, the thickness of the second part 252 gradually increases along the length direction X of the battery cell 20; the increase in the thickness of the second part 252 can make the surface of the second part 252 facing the flat part 221 gradually approach the flat part 221 along the length direction X of the battery cell 20, that is, the change in the thickness of the second part 252 is reflected on the side of the second part 252 facing the flat part 221, and can change the distance between the second part 252 and the flat part 221 in the length direction X of the battery cell 20.

[0117] In the arrangement direction of the flat part 221 and the bending part 222, the edge of the flat part 221 is the position where the flat part 221 is connected to the bending part 222; the thickness of the second part 252 gradually increases from the middle of the flat part 221 to the edge of the flat part 221, that is, the second part 252 is closer to the electrode assembly 22 at the connection part 254 between the flat part 221 and the bending part 222, so as to inhibit the expansion deformation amount of the electrode assembly 22 at this position, thereby reducing the situation of the electrode assembly 22 breaking at the connection part 254 between the flat part 221 and the bending part 222; at the same time, this setting can also make the distance between the middle of the flat part 221 and the second part 252 larger, so that the middle of the flat part 221 can have a larger expansion deformation space; this setting can make the expansion deformation amount of the flat part 221 gradually increase from its connection part 254 with the bending part 222 to its middle part, and make the expansion force gradually release to the position close to the middle of the flat part 221, so as to reduce the difference in the expansion deformation amount between the bending part 222 and the flat part 221 at the connection position between the two, thereby alleviating the problem of stress concentration.

[0118] When the battery cell 20 expands, the thickness setting of the second part 252 enables the flat part 221 to have a larger expansion deformation space and release more expansion force, thereby reducing the expansion deformation amount of the bending part 222 and narrowing the difference in expansion deformation amounts between the bending part 222 and the flat part 221, so as to relieve the problem of stress concentration.

[0119] In this embodiment, a buffer member 25 is arranged in the housing 21, the first part 251 of the buffer member 25 faces the bending part 222, and the first surface 2511 of the first part 251 is an arc surface. When the electrode assembly 22 expands, this setting can increase the contact area between the bending part 222 and the first surface 2511, thereby relieving the stress concentration; the second part 252 of the buffer member 25 faces the flat part 221, and the thickness of the second part 252 gradually increases from the middle of the flat part 221 to the edge of the flat part 221. This setting can enable the flat part 221 to have a larger expansion space at the position where the thickness of the second part 252 is smaller, thereby reducing the difference in expansion deformation amounts between the flat part 221 and the bending part 222. This setting can also make the buffer member 25 closer to the electrode assembly 22 at the position where the flat part 221 is connected to the bending part 222, so as to inhibit the expansion deformation amount at this position, thereby relieving the situation that the connection position between the bending part 222 and the flat part 221 is prone to fracture due to the difference in expansion deformation amounts.

[0120] In some embodiments, the bending part 222 is attached to and abuts against the first surface 2511.

[0121] The bending part 222 is attached to the first surface 2511, that is, the side surface of the bending part 222 has the same or substantially the same shape as the first surface 2511. For example, parameters such as the radian, central angle, and radius of the side surface of the bending part 222 and the first surface 2511 can be the same; this setting can better increase the contact area between the bending part 222 and the first surface 2511, thereby further reducing the stress concentration.

[0122] The bending part 222 abuts against the first surface 2511 so that the first part 251 can better limit the expansion deformation of the bending part 222. When the battery cell 20 expands, the expansion deformation of the bending part 222 will abut against the first surface 2511. According to the material of the buffer member 25, the first part 251 can inhibit the further expansion of the bending part 222 or provide resistance to the expansion of the bending part 222, thereby reducing the expansion deformation amount of the bending part 222, narrowing the difference between the expansion deformation amount of the bending part 222 and the expansion deformation amount of the flat part 221, and further reducing the stress concentration at the bending part 222 and the connection position between the bending part 222 and the flat part 221.

[0123] When the first surface 2511 of the first part 251 abuts against the bent portion 222, the first part 251 may only touch the bent portion 222, and in this case, there is no or substantially no interaction force between the first part 251 and the bent portion 222; the first surface 2511 may also abut against the bent portion 222 and apply a force pointing towards the inside of the housing 21 to the bent portion 222. Since the bent portion 222 is located on the opposite sides of the electrode assembly 22, the first parts 251 on both sides of the electrode assembly 22 can apply a force pointing towards the inside of the housing 21 to the adjacent bent portions 222. In this case, in addition to restricting the expansion of the bent portion 222, the first part 251 can also play a role in fixing the electrode assembly 22.

[0124] In this embodiment, the bent portion 222 is made to fit with the first surface 2511 to increase the contact area between the bent portion 222 and the first part 251, thereby alleviating the problem of stress concentration in the bent portion 222; the bent portion 222 is made to abut against the first surface 2511 to better inhibit the expansion deformation amount of the bent portion 222 through the first part 251, and reduce the difference in the expansion deformation amount between the bent portion 222 and the flat portion 221, thereby alleviating the problem of stress concentration at the connection position between the bent portion 222 and the flat portion 221 of the electrode assembly 22, and reducing the occurrence of the fracture of the electrode assembly 22.

[0125] Reference Figures 4 to 6 , in some embodiments, the first part 251 and the second part 252 are connected end to end in turn and alternately to form an inner space 253 for accommodating the electrode assembly 22; there is a first difference between the maximum length of the inner space 253 and the maximum length of the electrode assembly 22, and there is a second difference between the maximum width of the inner space 253 and the maximum width of the electrode assembly 22, and the first difference is less than or equal to the second difference.

[0126] Since the buffer member 25 is located between the electrode assembly 22 and the housing 21, the first part 251 and the second part 252 can both be structures on the peripheral side of the electrode assembly 22. In this case, the first part 251 and the second part 252 connected end to end in turn and alternately can form an annular structure surrounding the electrode assembly 22, and an inner space 253 with openings at both upper and lower ends is formed within this annular structure to accommodate the electrode assembly 22 in the inner space 253; according to the shapes of the first part 251 and the second part 252, the inner space 253 can be a prismatic space, an elliptical cylindrical space or a space of other shapes.

[0127] The maximum length of the inner space 253 refers to the maximum value of the dimension of the inner space 253 in the length direction X of the battery cell 20, and also refers to the dimension at the maximum length of the inner space 253. Reference Figure 5, the dimension shown as L1 in the figure is the maximum length of the inner space 253; since the first surface 2511 of the first part 251 is an arc surface, when the first part 251 is on both sides of the second part 252 in the length direction X of the battery cell 20, the maximum length of the inner space 253 is the maximum dimension of the inner space 253 in the length direction X of the battery cell 20.

[0128] The maximum length of the electrode assembly 22 is the maximum value of the dimensions of the electrode assembly 22 in the length direction X of the battery cell 20. Refer to Figure 5 , the dimension shown as L2 in the figure is the length of the electrode assembly 22; since the side surface of the bending part 222 is an arc structure, when the bending part 222 is on both sides of the flat part 221 in the length direction X, the maximum length of the electrode assembly 22 is the maximum dimension of the electrode assembly 22 in the length direction X of the battery cell 20.

[0129] The first difference refers to the difference between the inner space 253 and the electrode assembly 22 in the length direction X of the battery cell 20. Refer to Figure 5 , when the electrode assembly 22 is located in the middle of the inner space 253, the first difference is twice the dimension shown as L3 in the figure; the first difference is positively correlated with the size of the expansion deformation space of the bending part 222. The larger the value of the first difference, the larger the expansion deformation space of the bending part 222.

[0130] The maximum width of the inner space 253 refers to the maximum value of the dimensions of the inner space 253 in the width direction Y of the battery cell 20, and also refers to the dimension at the maximum width of the inner space 253. Refer to Figure 6 , the dimension shown as W1 in the figure is the width of the inner space 253; since the thickness of the second part 252 changes along the length direction X of the battery cell 20, the maximum length of the inner space 253 is the maximum dimension of the inner space 253 in the width direction Y of the battery cell 20.

[0131] The maximum width of the electrode assembly 22 is the maximum value of the dimensions of the electrode assembly 22 in the width direction Y of the battery cell 20. Refer to Figure 6 , the dimension shown as W2 in the figure is the maximum width of the electrode assembly 22.

[0132] The second difference refers to the difference between the inner space 253 and the electrode assembly 22 in the width direction Y of the battery cell 20. Refer to Figure 6 , when the electrode assembly 22 is located in the middle of the inner space 253, the second difference is twice the dimension shown as W3 in the figure; the second difference is positively correlated with the size of the expansion deformation space of the flat part 221. The larger the value of the second difference, the larger the expansion deformation space of the flat part 221.

[0133] Make the first difference less than or equal to the second difference, so that the expansion deformation amount of the bent portion 222 is less than that of the flat portion 221; since the expansion deformation space of the bent portion 222 is also positively correlated with the surface area of the bent portion 222, and the size of the expansion deformation space of the flat portion 221 is also positively correlated with the surface area of the flat portion 221, and the surface area of the flat portion 221 is usually larger than that of the bent portion 222, so when the first difference is less than or equal to the second difference, the expansion deformation space of the bent portion 222 is smaller than that of the flat portion 221.

[0134] Accordingly, when the electrode assembly 22 expands, the expansion deformation of the bent portion 222 will first abut against the first portion 251. After the bent portion 222 abuts against the first portion 251, it is not easy to expand further. At this time, the expansion force of the electrode assembly 22 will be transferred to the flat portion 221 and cause the flat portion 221 to expand further, so as to reduce the expansion deformation amount between the bent portion 222 and the flat portion 221 and relieve the fracture of the electrode assembly 22; since the flat portion 221 is relatively flat and has a large surface area, the contact area between the expansion of the flat portion 221 and the second portion 252 is large, and stress concentration is not likely to occur during the expansion of the flat portion 221, thus achieving the effect of relieving the fracture of the electrode assembly 22.

[0135] This embodiment provides some size ranges of the buffer member 25, so that the expansion deformation space of the bent portion 222 is smaller than that of the flat portion 221, reducing the difference in the expansion deformation amount between the bent portion 222 and the flat portion 221, thereby relieving the stress concentration problem at the connection position between the bent portion 222 and the flat portion 221 of the electrode assembly 22 and reducing the occurrence of fracture of the electrode assembly 22.

[0136] Reference Figure 4 、 Figure 5 , in some embodiments, the range of the first difference is 0 to 2 mm (millimeters); for example, the first difference can be 0, or can be 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm or other values.

[0137] Since the first difference is the difference between the size at the maximum length of the inner space 253 and the size at the maximum length of the electrode assembly 22, and the first difference is positively correlated with the size of the expansion deformation space of the bent portion 222, the first difference should not be too large to limit the expansion deformation amount of the bent portion 222 and reduce the difference in the expansion deformation amount between the flat portion 221 and the bent portion 222; the first difference should not be too small either, so as to facilitate the bent portion 222 to release part of the expansion force and at the same time reduce the assembly difficulty; accordingly, the first difference can be within a range that can make the bent portion 222 have a smaller expansion deformation space and can also make the bent portion 222 release part of the expansion force.

[0138] When the electrode assembly 22 is located in the middle of the inner space 253, the distance L3 between the bending portions 222 on both sides of the electrode assembly 22 in the length direction X and the adjacent first surface 2511 is half of the first difference, that is, the range of this distance L3 is 0 to 1 mm.

[0139] Exemplarily, the first difference can be 0. At this time, the first surface 2511 is in side contact with the bending portion 222, the first portion 251 abuts against the bending portion 222, and the first portion 251 can better inhibit the expansion deformation of the bending portion 222.

[0140] Exemplarily, the first difference can be 1 mm. At this time, there is a small gap between the first surface 2511 and the bending portion 222. When the electrode assembly 22 expands, this setting can both enable the bending portion 222 to have a certain expansion deformation space to release part of the expansion force of the electrode assembly 22, and can also inhibit the excessive expansion deformation of the bending portion 222, thereby reducing the difference in the expansion deformation amounts between the bending portion 222 and the flat portion 221.

[0141] Exemplarily, the first difference can be 2 mm. At this time, there is a gap between the first surface 2511 and the bending portion 222. When the electrode assembly 22 expands, this setting can both enable the bending portion 222 to release more expansion force and can also limit the expansion deformation of the bending portion 222.

[0142] This embodiment provides a range of the difference between the length of the inner space 253 and the length of the electrode assembly 22, so that the expansion deformation space of the bending portion 222 is small, thereby being able to reduce the difference in the expansion deformation amounts between the bending portion 222 and the flat portion 221.

[0143] Reference Figure 4 、 Figure 5 , in some embodiments, the range of the first difference is 0 to 1 mm; exemplarily, the first difference can be 0, or can also be 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm or other values.

[0144] When the electrode assembly 22 is located in the middle of the inner space 253, the distance L3 between the bending portions 222 on both sides of the electrode assembly 22 in the length direction X and the adjacent first surface 2511 is half of the first difference, that is, the range of this distance L3 is 0 to 0.5 mm.

[0145] Exemplarily, the first difference may be 0.5 mm. At this time, there is a small gap between the first surface 2511 and the bent portion 222. When the electrode assembly 22 expands, this setting can not only enable the bent portion 222 to have a certain space for expansion deformation to release part of the expansion force of the electrode assembly 22, but also inhibit the excessive expansion deformation of the bent portion 222, thereby reducing the difference in the expansion deformation amounts between the bent portion 222 and the flat portion 221. At the same time, this setting can also provide an error space for the processing of the buffer member 25 and the installation of the electrode assembly 22, reducing the processing difficulty of the battery cell 20.

[0146] This embodiment further provides a range of the difference between the length of the inner space 253 and the length of the electrode assembly 22 to better inhibit the expansion deformation of the bent portion 222 and better reduce the difference in the expansion deformation amounts between the bent portion 222 and the flat portion 221.

[0147] Reference Figure 4 、 Figure 6 , in some embodiments, the minimum value of the second difference is 0.5 times the difference between the width of the accommodating cavity 211 and the width of the electrode assembly 22, and the maximum value of the second difference is the difference between the width of the accommodating cavity 211 and the width of the electrode assembly 22.

[0148] The width of the accommodating cavity 211 refers to the dimension of the accommodating cavity 211 in the width direction Y of the battery cell 20. When the housing 21 is in the shape of a cuboid, the width of the accommodating cavity 211 is the distance between the two inner side surfaces of the housing 21 in its width direction Y; the difference between the width of the accommodating cavity 211 and the width of the electrode assembly 22 is the distance between the two sides of the electrode assembly 22 in the width direction Y of the battery cell 20 and the adjacent inner side surface of the housing 21.

[0149] Since the second difference is the difference between the dimension at the maximum width of the inner space 253 and the dimension at the maximum width of the electrode assembly 22, and the second difference is positively correlated with the size of the expansion deformation space of the flat portion 221, the second difference should be relatively large so that the flat portion 221 can have a relatively large expansion deformation space to reduce the difference in the expansion deformation amounts between the flat portion 221 and the bent portion 222, and at the same time it is also convenient for the flat portion 221 to release more expansion force; the second difference should not be too large at the same time to reduce its negative impact on the energy density of the battery cell 20; accordingly, the second difference can be within a range that can not only enable the flat portion 221 to have a relatively large expansion deformation space but also reduce the negative impact on the energy density of the battery cell 20.

[0150] The minimum value of the second difference is the lower limit value of the second difference range. When the second difference is this minimum value, the expansion deformation space of the flat part 221 is small and the negative impact on the energy density of the battery cell 20 is small; the maximum value of the second difference is the upper limit value of the second difference range. When the second difference is this maximum value, the expansion deformation space of the flat part 221 is large, and the difference in the expansion deformation amounts between the flat part 221 and the bent part 222 is small.

[0151] The minimum value of the second difference is half of the difference between the widths of the accommodation cavity 211 and the electrode assembly 22. At this time, the minimum thickness of the second part 252 is half of the difference between the widths of the accommodation cavity 211 and the electrode assembly 22; the maximum value of the second difference is the difference between the widths of the accommodation cavity 211 and the electrode assembly 22. At this time, the minimum thickness of the second part 252 is zero, that is, there is a partial disconnection structure on the second part 252, so that the expansion of the flat part 221 can abut against the inner side surface of the housing 21.

[0152] Accordingly, the range of the second difference is 0.5 times to 1 time the difference between the widths of the accommodation cavity 211 and the electrode assembly 22; for example, the second difference can be 0.5 times, 0.5 times, 0.6 times, 0.7 times, 0.8 times, 0.9 times, 1 time of the difference between the two or other values.

[0153] This embodiment provides a range of the difference between the width of the inner space 253 and the width of the electrode assembly 22, so that the expansion deformation space of the flat part 221 is large, so as to reduce the difference in the expansion deformation amounts between the bent part 222 and the flat part 221, and also enable more expansion force of the electrode assembly 22 to be released at the flat part 221, thereby reducing the harm of the expansion of the electrode assembly 22.

[0154] Reference Figure 4 、 Figure 6 In some embodiments, the minimum value of the second difference is greater than or equal to 2 mm; when the maximum value of the second difference is the difference between the widths of the accommodation cavity 211 and the electrode assembly 22, the minimum value of the second difference can be 2 mm, or can be 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm or other values.

[0155] The minimum value of the second difference limits the minimum value of the expansion deformation space of the flat part 221. When the electrode assembly 22 expands, this setting can enable the flat part 221 to have a relatively sufficient expansion deformation space, so as to reduce the difference in the expansion deformation amounts between the bent part 222 and the flat part 221; at the same time, this setting also limits the minimum thickness of the second part 252, so that the minimum thickness of the second part 252 is not too large, thereby reducing the space occupied by the buffer member 25 in the accommodation cavity 211.

[0156] This embodiment provides a range of the difference between the width of the inner space 253 and the width of the electrode assembly 22, so that the expansion deformation space of the flat part 221 is relatively large, reducing the difference in the expansion deformation amounts between the bending part 222 and the flat part 221, and also facilitating the release of the expansion force of the electrode assembly 22.

[0157] Reference Figure 4 、 Figure 7 , in some embodiments, the buffer member 25 abuts against the connecting portion of the bending part 222 and the flat part 221 at the connecting position of the first part 251 and the second part 252.

[0158] Since in the current situation where the electrode assembly 22 expands, the expansion deformation amount of the bending part 222 is greater than that of the flat part 221, the position where the bending part 222 and the flat part 221 are connected is likely to break due to the difference in their expansion deformation amounts; accordingly, the buffer member 25 abuts against the electrode assembly 22 at the connecting position of the first part 251 and the second part 252 to inhibit the expansion deformation amount of the electrode assembly 22 at the connecting portion of the bending part 222 and the flat part 221, thereby alleviating the stress concentration phenomenon at this place and reducing the risk of the electrode assembly 22 breaking.

[0159] Since the expansion deformation space of the bending part 222 is smaller than that of the flat part 221, the expansion deformation amount of the bending part 222 should also be smaller than that of the flat part 221; also, since the thickness of the second part 252 gradually increases from the middle of the flat part 221 to the edge of the flat part 221, and the connecting portion of the bending part 222 and the flat part 221 is located at the edge of the flat part 221, the thickness of the second part 252 gradually decreases from the connecting portion of the bending part 222 and the flat part 221 to the middle of the flat part 221, and the expansion deformation amount of the flat part 221 near the connecting portion of the bending part 222 and the flat part 221 is also relatively small; accordingly, the buffer member 25 abutting against the connecting portion of the bending part 222 and the flat part 221 can better alleviate the stress concentration phenomenon at this place and reduce the risk of the electrode assembly 22 breaking at this place.

[0160] In this embodiment, the buffer member 25 can abut against the connecting portion of the bending part 222 and the flat part 221 to squeeze the electrode assembly 22 at this portion, inhibiting the expansion deformation amount of the electrode assembly 22 at this portion, thereby reducing the risk of the electrode assembly 22 breaking at this position.

[0161] Reference Figure 4 、 Figure 6 、 Figure 7 , in some embodiments, in the width direction of the electrode assembly 22, the range of the difference between the dimension of the inner space 253 at the connecting position of the first part 251 and the second part 252 and the width of the electrode assembly 22 is 0 to 1 mm.

[0162] The width of the electrode assembly 22 at the connection between the bent portion 222 and the flat portion 221 is the dimension of the electrode assembly 22 in the width direction Y of the battery cell 20, which is also the dimension shown as W2 in Figure 5 the figure.

[0163] The connection position between the first portion 251 and the second portion 252 in the buffer member 25 is called the connection portion 254. The difference between the dimension of the inner space 253 at the connection portion 254 and the width of the electrode assembly 22 at the connection between the bent portion 222 and the flat portion 221 is Figure 7 the dimension shown as W4 in the figure; the range of this difference is 0 to 1 mm. For example, this difference can be 0, or it can be 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm or other values.

[0164] Since the thickness of the second portion 252 gradually increases from the middle of the flat portion 221 to the edge of the flat portion 221, and the connection between the bent portion 222 and the flat portion 221 is located at the edge of the flat portion 221, the thickness of the second portion 252 is the largest at the connection between the bent portion 222 and the flat portion 221. The expansion deformation amount of the flat portion 221 near the connection between the bent portion 222 and the flat portion 221 is also small, and the expansion deformation amount of the bent portion 222 is also less restricted by the first portion 251. Therefore, this setting can relieve the stress concentration phenomenon at the connection between the bent portion 222 and the flat portion 221 of the electrode assembly 22 and reduce the risk of the electrode assembly 22 breaking at this position.

[0165] For example, the difference between the dimension of the inner space 253 at the connection portion 254 and the width of the electrode assembly 22 at the connection between the bent portion 222 and the flat portion 221 can be 0. At this time, the buffer member 25 abuts against the electrode assembly 22 at the connection portion 254 to better relieve the stress concentration phenomenon at this position and reduce the risk of the electrode assembly 22 breaking at this position.

[0166] For example, the difference between the dimension of the inner space 253 at the connection portion 254 and the width of the electrode assembly 22 at the connection between the bent portion 222 and the flat portion 221 can be 0.5 mm. At this time, the electrode assembly 22 has a small deformation space at this position, so that the electrode assembly 22 can also release part of the expansion force at this position, and at the same time, the buffer member 25 can also inhibit the expansion deformation amount of the electrode assembly 22 at this position, thereby relieving the stress concentration phenomenon at this position.

[0167] For example, the difference between the dimension of the inner space 253 at the connection portion 254 and the width of the electrode assembly 22 at the connection between the bent portion 222 and the flat portion 221 can be 1 mm. On the premise that the buffer member 25 can inhibit the expansion deformation amount of the electrode assembly 22 at this position, this setting can enable the electrode assembly 22 to release more expansion force at this position.

[0168] In this embodiment, the buffer member 25 is positioned closer to the electrode assembly 22 at the connection between the bent portion 222 and the flat portion 221, so as to inhibit the amount of expansion deformation of the electrode assembly 22 at this portion, thereby reducing the risk of fracture of the electrode assembly 22 at this position; at the same time, it can also enable the electrode assembly 22 to release part of the expansion force at this position, thereby reducing the harm caused by the expansion of the electrode assembly 22.

[0169] Reference Figures 4 to 7 , in some embodiments, the second part 252 includes a second surface 2521 facing the flat portion 221. The second surface 2521 is connected to the first surface 2511 and a connection portion 254 is formed at the connection position; from the connection portion 254 to the middle of the first surface 2511, the distance between the first surface 2511 and the bent portion 222 remains unchanged or gradually increases; in the direction pointing from the connection portion 254 to the second surface 2521, the distance between the second surface 2521 and the flat portion 221 gradually increases.

[0170] The second surface 2521 refers to the surface of the second part 252 facing the flat portion 221; the thickness of the second part 252 varies along the length direction X of the battery cell 20. In the length direction of the battery cell 20, the second surface 2521 gradually approaches the flat portion 221 from its middle to its edge; in the case of the expansion of the battery cell 20, this setting can make the amount of expansion deformation of the flat portion 221 gradually increase from the edge of the flat portion 221 to the middle of the flat portion 221, and make the expansion force gradually release to the position closer to the middle of the flat portion 221, so as to reduce the difference in the amount of expansion deformation between the bent portion 222 and the flat portion 221 near the connection portion 254, thereby alleviating the problem of stress concentration.

[0171] The connection portion 254 refers to the structure of the buffer member 25 at the connection between the first surface 2511 and the second surface 2521. The connection portion 254 is opposite to the connection portion between the flat portion 221 and the bent portion 222 in the electrode assembly 22 to limit the expansion deformation of the electrode assembly 22 at the connection between the flat portion 221 and the bent portion 222.

[0172] From the connection portion 254 to the middle of the first surface 2511, that is, from the edge of the first surface 2511 to the middle of the first surface 2511, the distance between the first surface 2511 and the bent portion 222 can remain unchanged. At this time, the distance between the first surface 2511 and the bent portion 222 is relatively small, so that the first part 251 can better play the role of inhibiting the expansion deformation of the bent portion 222.

[0173] From the self - connecting portion 254 to the middle of the first surface 2511, the distance between the first surface 2511 and the bending portion 222 can also gradually increase. At this time, the distance between the first portion 251 and the bending portion 222 is smaller near the connecting portion 254, so that the difference between the expansion deformation amount of the bending portion 222 near the flat portion 221 and the expansion deformation amount of the connected portion of the flat portion 221 and the bending portion 222 is smaller, thereby being able to relieve the stress concentration situation; at the same time, the first portion 251 can also provide space for the expansion deformation of the bending portion 222 to facilitate the release of part of the expansion force.

[0174] The direction pointed by the connecting portion 254 to the second surface 2521 means: in the length direction X of the battery cell 20, the direction from the edge of the second surface 2521 to the middle of the second surface 2521; in this direction, the distance between the second surface 2521 and the flat portion 221 gradually increases, so that the difference between the expansion deformation amount of the flat portion 221 near the bending portion 222 and the expansion deformation amount of the connected portion of the flat portion 221 and the bending portion 222 is smaller, thereby being able to relieve the stress concentration situation; at the same time, the second portion 252 can also provide space for the expansion of the flat portion 221 to facilitate the release of part of the expansion force.

[0175] Accordingly, the distance between the connecting portion 254 and the electrode assembly 22 is the smallest. Because currently, when the electrode assembly 22 expands, the expansion deformation amount of the bending portion 222 is greater than that of the flat portion 221, resulting in the position where the bending portion 222 is connected to the flat portion 221 being prone to fracture due to the difference in their expansion deformation amounts; accordingly, the distance between the connecting portion 254 and the electrode assembly 22 is made the smallest to suppress the expansion deformation amount of the electrode assembly 22 at the connected portion of the bending portion 222 and the flat portion 221 through the connecting portion 254, thereby relieving the stress concentration phenomenon at this place and reducing the risk of fracture of the electrode assembly 22.

[0176] At the same time, this setting can also suppress the expansion deformation amount of the bending portion 222 and the flat portion 221 near the connected portion of the two, so as to further reduce the difference in the expansion deformation amounts of the electrode assembly 22 at the connected portion of the bending portion 222 and the flat portion 221, thereby being able to better relieve the stress concentration phenomenon at this place.

[0177] In this embodiment, the distance between the buffer member 25 and the connected portion of the flat portion 221 and the bending portion 222 is made smaller, and at the same time, the bending portion 222 and the flat portion 221 have deformation space, so that the buffer member 25 can not only suppress the expansion deformation of the electrode assembly 22 at the connected portion of the flat portion 221 and the bending portion 222, but also release the expansion force of the electrode assembly 22.

[0178] Reference Figures 4 to 7, in some embodiments, the maximum value of the spacing between the second surface 2521 and the flat portion 221 is greater than or equal to the maximum value of the spacing between the first surface 2511 and the curved portion 222.

[0179] Since the spacing between the second surface 2521 and the flat portion 221 varies gradually in the length direction X of the battery cell 20, there is a maximum value for the spacing between the second surface 2521 and the flat portion 221. Also, since the second surface 2521 gradually moves away from the flat portion 221 from its edge towards its middle, the maximum spacing between the second surface 2521 and the flat portion 221 is formed at the middle of the second surface 2521.

[0180] When the spacing between the first surface 2511 and the curved portion 222 remains unchanged, the maximum value of the spacing between the first surface 2511 and the curved portion 222 is the spacing between the first surface 2511 and the curved portion 222; when the first surface 2511 gradually moves away from the curved portion 222 from its edge towards its middle, the maximum spacing between the first surface 2511 and the curved portion 222 is formed at the middle of the first surface 2511.

[0181] When the maximum value of the spacing between the second surface 2521 and the flat portion 221 is greater than the maximum value between the first surface 2511 and the curved portion 222, the expansion deformation space of the flat portion 221 is greater than that of the curved portion 222, so as to guide more of the expansion force of the electrode assembly 22 to be released at the flat portion 221, thereby reducing the difference between the expansion deformation amount of the curved portion 222 and the expansion deformation amount of the flat portion 221; since the surface area of the flat portion 221 is usually larger, the same expansion force forms a smaller expansion deformation amount at the flat portion 221 than at the curved portion 222, so this setting can also reduce the deformation hazard caused by the expansion of the electrode assembly 22.

[0182] When the maximum value of the spacing between the second surface 2521 and the flat portion 221 is equal to the maximum value between the first surface 2511 and the curved portion 222, since the surface area of the flat portion 221 is usually larger, this setting can also make the expansion deformation space of the flat portion 221 greater than that of the curved portion 222.

[0183] This embodiment can make the expansion deformation space of the curved portion 222 smaller than that of the flat portion 221, so as to reduce the difference in the expansion deformation amounts between the curved portion 222 and the flat portion 221, thereby alleviating the problem of stress concentration at the connection position between the curved portion 222 and the flat portion 221 of the electrode assembly 22 and reducing the occurrence of the fracture of the electrode assembly 22.

[0184] In some embodiments, the height of the buffer member 25 is less than or equal to the height of the electrode assembly 22.

[0185] The height of the buffer member 25 refers to the dimension of the buffer member 25 in the height direction Z of the battery cell 20, and the height of the motor assembly refers to the dimension of the electrode assembly 22 in the height direction Z of the battery cell 20.

[0186] The height of the buffer member 25 can be equal to the height of the electrode assembly 22 so that the buffer member 25 completely covers the electrode assembly 22 in the height direction Z of the battery cell 20, thereby enabling the buffer member 25 to better limit the expansion deformation of the electrode assembly 22; the height of the buffer member 25 can also be less than the height of the electrode assembly 22. In this case, the buffer member 25 only covers a part of the electrode assembly 22 in the height direction Z of the battery cell 20. This setting enables the buffer member 25 to not only limit the expansion deformation of the electrode assembly 22 but also reduce the occupation of the space of the accommodation cavity 211 by the buffer member 25.

[0187] In the technical solution of this embodiment, the height of the buffer member 25 is made less than or equal to the height of the electrode assembly 22 so that the buffer member 25 can not only inhibit the expansion deformation of the bending portion 222 but also reduce the space occupation of the buffer member 25.

[0188] In some embodiments, the range of the difference between the height of the electrode assembly 22 and the height of the buffer member 25 is 0 to 5 mm; for example, the difference between the height of the electrode assembly 22 and the height of the buffer member 25 can be 0, or can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm or other values.

[0189] Since the dimensions of the positive electrode plate and the negative electrode plate in the electrode assembly 22 in the height direction Z of the battery cell 20 are not the same, and the dimension of the positive electrode plate in the height direction Z of the battery cell 20 is usually smaller than that of the negative electrode plate in the height direction Z of the battery cell 20, that is, the two sides of the negative electrode plate in the height direction Z of the battery cell 20 usually exceed the positive electrode plate, the expansion force of the electrode assembly 22 in the part where the negative electrode plate exceeds the positive electrode plate is usually small, and the expansion deformation amount is small.

[0190] Accordingly, making the range of the difference between the height of the electrode assembly 22 and the height of the buffer member 25 be 0 to 5 mm, when the electrode assembly 22 expands, this setting can prevent the electrode assembly 22 from being prone to stress concentration at the edge of the buffer member 25 in the height direction Z, so that the buffer member 25 can not only limit the expansion deformation amount of the electrode assembly 22 but also reduce the negative impact on the energy density of the battery cell 20.

[0191] For example, the difference between the height of the electrode assembly 22 and the height of the buffer member 25 can be 0. At this time, the height of the buffer member 25 is the same as the height of the electrode assembly 22 to facilitate the buffer member 25 to limit the expansion deformation amount of the electrode assembly 22.

[0192] Exemplarily, the difference between the height of the electrode assembly 22 and the height of the buffer member 25 can be 2.5 mm. At this time, the height of the buffer member 25 is relatively low, so that the buffer member 25 can not only better limit the expansion deformation amount of the electrode assembly 22, but also reduce the negative impact on the energy density of the battery cell 20.

[0193] Exemplarily, the difference between the height of the electrode assembly 22 and the height of the buffer member 25 can be 5 mm. At this time, the height of the buffer member 25 is even lower, so as to reduce the occupation of the space of the accommodation cavity 211 by the buffer member 25, thereby reducing the negative impact of the buffer member 25 on the energy density of the battery cell 20.

[0194] This embodiment provides some ranges of the height difference between the buffer member 25 and the electrode assembly 22. When the electrode assembly 22 expands, this setting can reduce the stress concentration at the edge of the electrode assembly 22 in the height direction of the buffer member 25, and at the same time can also reduce the negative impact of the buffer member 25 on the energy density of the battery cell 20.

[0195] In some embodiments, the height of the buffer member 25 is greater than or equal to the height of the electrode assembly 22.

[0196] In the current battery cell 20, in order to reduce the risk of short circuit caused by the contact between the electrode assembly 22 and structures such as the end cap 23 and the housing 21, an insulating member is usually provided on the side of the end cap 23 facing the electrode assembly 22 to separate the electrode assembly 22 and the end cap 23.

[0197] Accordingly, when the height of the buffer member 25 is greater than or equal to the height of the electrode assembly 22, after the end cap 23 is installed, the upper end of the buffer member 25 in the height direction Z of the battery cell 20 can abut against the end cap 23 to form a space between the end cap 23 and the electrode assembly 22 and reduce the risk of the electrode assembly 22 contacting the end cap 23; when the height of the buffer member 25 is greater than the height of the electrode assembly 22, an insulating member may not be provided on the side of the end cap 23 facing the electrode assembly 22, so as to reduce the number of structural members in the accommodation cavity 211 and reduce the processing difficulty of the battery cell 20.

[0198] In this embodiment, the height of the buffer member 25 is made greater than the height of the electrode assembly 22 so that the buffer member 25 can also be used to separate the electrode assembly 22 and the end cap 23 of the battery cell 20. At this time, an insulating member may no longer be provided on the side of the end cap 23 facing the electrode assembly 22, thereby reducing the number of internal components of the battery cell 20 and the processing difficulty.

[0199] In some embodiments, the range of the difference between the height of the buffer member 25 and the height of the electrode assembly 22 is 0-10 mm; exemplarily, the difference between the height of the buffer member 25 and the height of the electrode assembly 22 can be 0, or can be 2 mm, 4 mm, 6 mm, 8 mm, 10 mm or other values.

[0200] Exemplarily, the difference in height between the buffer member 25 and the electrode assembly 22 may be 0. In this case, the height of the buffer member 25 is the same as that of the electrode assembly 22, so that the buffer member 25 can limit the amount of expansion deformation of the electrode assembly 22.

[0201] Exemplarily, the difference in height between the buffer member 25 and the electrode assembly 22 may be 5 mm. In this case, the height of the portion of the buffer member 25 that protrudes above the electrode assembly 22 is relatively low, so that the buffer member 25 can not only separate the electrode assembly 22 from the end cap 23, but also reduce the occupation of the space of the accommodation cavity 211 by the buffer member 25.

[0202] Exemplarily, the difference in height between the buffer member 25 and the electrode assembly 22 may be 10 mm. In this case, the height of the portion of the buffer member 25 that protrudes above the electrode assembly 22 is relatively high, and a larger space is formed between the end cap 23 and the electrode assembly 22, so that the buffer member 25 can better separate the electrode assembly 22 from the end cap 23, thereby better reducing the risk of the electrode assembly 22 contacting the end cap 23.

[0203] This embodiment provides some ranges of the difference in height between the buffer member 25 and the electrode assembly 22, so that the buffer member 25 can not only limit the amount of expansion deformation of the electrode assembly 22, but also separate the electrode assembly 22 from the end cap 23, and at the same time can also reduce the occupation of the space of the accommodation cavity 211 by the buffer member 25.

[0204] In some embodiments, the range of the difference in height between the buffer member 25 and the electrode assembly 22 is 3 to 10 mm; Exemplarily, the difference in height between the buffer member 25 and the electrode assembly 22 may be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm or other values.

[0205] Exemplarily, the difference in height between the buffer member 25 and the electrode assembly 22 may be 3 mm. In this case, the height of the portion of the buffer member 25 that protrudes above the electrode assembly 22 is relatively low, so as to reduce the occupation of the space of the accommodation cavity 211 by the buffer member 25.

[0206] Exemplarily, the difference in height between the buffer member 25 and the electrode assembly 22 may be 6.5 mm. In this case, the height of the portion of the buffer member 25 that protrudes above the electrode assembly 22 is moderate, so that the buffer member 25 can not only separate the electrode assembly 22 from the end cap 23, but also reduce the occupation of the space of the accommodation cavity 211 by the buffer member 25.

[0207] Exemplarily, the difference in height between the buffer member 25 and the electrode assembly 22 may be 10 mm. At this time, the height of the part of the buffer member 25 protruding above the electrode assembly 22 is relatively high, and a larger space is formed between the end cap 23 and the electrode assembly 22, so that the buffer member 25 can better separate the electrode assembly 22 from the end cap 23, thereby better reducing the risk of the electrode assembly 22 contacting the end cap 23.

[0208] This embodiment further provides a range of height differences between the buffer member 25 and the electrode assembly 22, so that the buffer member 25 can better separate the electrode assembly 22 from the end cap 23 and reduce the short - circuit situation between the electrode assembly 22 and the end cap 23.

[0209] Reference Figure 4 、 Figure 7 In some embodiments, the buffer member 25 abuts against the housing 21.

[0210] The buffer member 25 abuts against the inner wall of the housing 21, that is, the side of the buffer member 25 facing away from the electrode assembly 22 abuts against the inner - facing side of the housing 21; since the buffer member 25 is used to abut against the electrode assembly 22 and inhibit its further deformation after the electrode assembly 22 expands and deforms to a certain extent, making the buffer member 25 abut against the housing 21 can provide support for the buffer member 25 through the housing 21 and reduce the situation of displacement and misalignment of the buffer member 25 when the electrode assembly 22 expands; the housing 21 can also share part of the force exerted by the electrode assembly 22 on the buffer member 25 to reduce the risk of damage to the buffer member 25; at the same time, making the buffer member 25 abut against the housing 21 also facilitates the fixing and installation of the buffer member 25.

[0211] In the technical solution of this embodiment, the buffer member 25 is made to abut against the inner wall of the housing 21, so as to facilitate fixing the buffer member 25 in the housing 21 and also facilitate the housing 21 to provide support for the buffer member 25, so that the buffer member 25 can better exert a force on the electrode assembly 22 to limit the expansion and deformation of the electrode assembly 22.

[0212] Reference Figure 4 、 Figure 7 In some embodiments, the buffer member 25 is spaced from the housing 21, and the spacing range between the buffer member 25 and the housing 21 is 0 - 0.5 mm.

[0213] The buffer member 25 is spaced from the housing 21, that is, there is a gap between the side of the buffer member 25 facing away from the electrode assembly 22 and the inner - facing side of the housing 21; when there are gaps between the buffer member 25 and the housing 21 and the electrode assembly 22, the buffer member 25 can be provided at the bottom of the housing 21 by welding, bonding or other means, or the buffer member 25 can be fixed in the housing 21 through other structural members.

[0214] The distance between the buffer member 25 and the housing 21 is the distance between the side of the buffer member 25 facing away from the electrode assembly 22 and the inner side of the housing 21 facing inward. Refer to Figure 7 , this distance is the dimension shown as W5 in the figure; the range of this distance is 0 to 0.5 mm. For example, this distance can be 0, or it can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm or other values.

[0215] This embodiment provides some gap dimensions between the buffer member 25 and the inner wall of the housing 21, so that there is a gap between the buffer member 25 and the inner wall of the housing 21 to reduce the assembly difficulty of the buffer member 25.

[0216] Refer to Figure 9 , in some embodiments, the number of electrode assemblies 22 is at least two. Each electrode assembly 22 is arranged along the width direction of the battery cell 20, and the adjacent flat parts 221 are in contact with each other; the first part 251 includes at least two first surfaces 2511 arranged along the width direction of the battery cell 20, and each first surface 2511 is opposite to the adjacent bending part 222 respectively.

[0217] The battery cell 20 includes at least two electrode assemblies 22, that is, at least two electrode assemblies 22 are accommodated in the housing 21. The number of electrode assemblies 22 can be two, or three or more.

[0218] Each electrode assembly 22 is arranged along the width direction Y of the battery cell 20. At this time, the adjacent flat parts 221 of the adjacent two battery cells 20 are opposite to each other and in contact with each other, that is, the adjacent two electrode assemblies 22 are in surface contact, so that there is a large contact area between the adjacent two electrode assemblies 22.

[0219] In the case of the expansion of each electrode assembly 22, this setting can enable the adjacent flat parts 221 of the adjacent two electrode assemblies 22 to contact and expand with each other, so as to reduce the problem of stress concentration at the contact part of the adjacent electrode assemblies 22.

[0220] The first part 251 includes at least two first surfaces 2511, that is, the number of the first surfaces 2511 can be two, or three or more; each first surface 2511 is arranged along the width direction Y of the battery cell 20, and each first surface 2511 can be connected in sequence to form a special-shaped surface on the side of the first part 251 facing the electrode assembly 22; each first surface 2511 is opposite to the adjacent bending part 222 respectively, so that the expansion deformation amount of each bending part 222 can be limited by the corresponding first surface 2511.

[0221] For example, the number of the first surfaces 2511 on a first part 251 may be the same as the number of the electrode assemblies 22, so that each first surface 2511 can respectively face the bent portions 222 of the electrode assemblies 22, thereby enabling the expansion deformation amounts of the bent portions 222 to be respectively limited by the corresponding first surfaces 2511.

[0222] In this embodiment, the battery cell 20 includes at least two electrode assemblies 22, the first part 251 includes at least two first surfaces 2511, and each first surface 2511 respectively faces the adjacent bent portions 222, so that each first surface 2511 can respectively limit the expansion of each bent portion 222, thereby better limiting the expansion of the bent portions 222 and reducing the force exerted on the adjacent electrode assemblies 22 by the expansion of the bent portions 222.

[0223] Reference Figure 8 、 Figure 9 In some embodiments, a partition groove 2522 is provided on the second part 252, and the partition groove 2522 is used to partition the second part 252 into two sub-parts 2523 that are spaced apart along the length direction of the battery cell 20.

[0224] The partition groove 2522 refers to a groove structure formed on the second part 252. The partition groove 2522 can penetrate through the second part 252 along the thickness direction of the second part 252 to partition the second part 252 into two sub-parts 2523, and the two sub-parts 2523 are respectively located on opposite sides of the partition groove 2522 along the length direction X of the battery cell 20. At this time, the second surface 2521 is also partitioned into two parts by the partition groove 2522 and is respectively located on the two sub-parts 2523; the partition groove 2522 can be a straight groove or a curved groove structure; the reference line in the length direction of the partition groove 2522 can be parallel or substantially parallel to the height direction Z of the battery cell 20; in the length direction X of the battery cell 20, the partition groove 2522 can be located in the middle of the second part 252 or close to one side of the second part 252.

[0225] The sub-part 2523 refers to a partial structure of the second part 252. After the second part 252 is cut by the partition groove 2522, the sub-part 2523 is the structure formed on opposite sides of the partition groove 2522; in the length direction X of the battery cell 20, one side of the sub-part 2523 faces the partition groove 2522, and the other side of the sub-part 2523 is connected to the first part 251.

[0226] Exemplarily, when there are two first parts 251 and two second parts 252 in both the first part 251 and the second part 252, and the two first parts 251 and the two second parts 252 are alternately connected end to end in sequence, partition grooves 2522 can be provided on both of the two second parts 252; at this time, the buffer member 25 is partitioned into two sub-structures by the partition grooves 2522, and each sub-structure includes one first part 251 and two sub-parts 2523 connected to the first part 251.

[0227] It can be understood that the thickness of the second part 252 at the partition groove 2522 can be regarded as 0. At this time, the expansion deformation space of the part of the flat part 221 opposite to the partition groove 2522 is relatively large, and the expansion deformation of the part of the flat part 221 opposite to the partition groove 2522 can abut against the housing 21.

[0228] In this embodiment, the partition groove 2522 is provided to partition the second part 252 into two sub-parts 2523, so that the flat part 221 can have a larger expansion deformation space; at the same time, this setting can also reduce the occupation of the space of the accommodation cavity 211 by the buffer member 25.

[0229] Reference Figure 8 、 Figure 9 , in some embodiments, chamfers are provided on the edges of one side of any one of the two sub-parts 2523 facing the other.

[0230] The chamfer refers to an inclined surface or curved surface structure formed on the sub-part 2523. The chamfer is formed on the edge of the sub-part 2523 on the side facing the other sub-part 2523. The chamfer can be a rounded corner, a semi-circular corner, an oblique angle or a chamfer structure of other shapes; on the side of the sub-part 2523 facing the other sub-part 2523, the chamfer can be formed only on the edge of the sub-part 2523 facing the electrode assembly 22, or chamfers can be formed on the edges of the sub-part 2523 facing both the electrode assembly 22 and the housing 21.

[0231] After the second part 252 is cut off by the partition groove 2522, the edge of one side of the sub-part 2523 facing the other sub-part 2523 is likely to form an edge. When the electrode assembly 22 expands, stress concentration is likely to occur at the edge of the flat part 221 at this edge, which is likely to cause the electrode assembly 22 to break at the edge; accordingly, chamfers are provided on the edges of the sub-part 2523 on the side facing the other sub-part 2523. When the electrode assembly 22 expands, this setting can reduce the risk of stress concentration near the partition groove 2522 of the electrode assembly 22.

[0232] In this embodiment, chamfers are provided on the edges of the sub-part 2523. When the electrode assembly 22 expands, this setting can relieve the stress concentration phenomenon at the edges of the sub-part 2523 of the electrode assembly 22.

[0233] In some embodiments, the buffer member 25 is an elastic member.

[0234] The buffer member 25 is an elastic member, that is, the buffer member 25 has a certain deformation ability and a certain amount of deformation under the action of an external force; the material of the buffer member 25 may include rubber, elastic limit or other elastic materials.

[0235] Because the elastic member has a certain amount of deformation, when the electrode assembly 22 expands, even if the electrode assembly 22 abuts against the buffer member 25, it still has a certain deformation space. Therefore, when the buffer member 25 is an elastic member, the gap between the buffer member 25 and the electrode assembly 22 can be reduced to reduce the occupation of the space of the accommodation cavity 211 by the buffer member 25; at the same time, when the electrode assembly 22 expands and abuts against the buffer member 25, the electrode assembly 22 will continue to be resisted by the buffer member 25 when it expands and deforms further. At this time, the buffer member 25 can absorb part of the expansion force of the electrode assembly 22, so as to facilitate the release of the expansion force of the electrode assembly 22.

[0236] In this embodiment, the buffer member 25 is an elastic member. When the electrode assembly 22 expands, this setting can provide an expansion space for the electrode assembly 22 to facilitate the release of the expansion force of the electrode assembly 22.

[0237] In some embodiments where the buffer member 25 is an elastic member, the compression ratio range of the buffer member 25 is 0-70%.

[0238] The compression ratio of a material refers to the ratio of the maximum deformation amount of the material to the original thickness. Among them, the maximum deformation amount of the material means: when the material deforms under the action of an external force, the maximum deformation amount of the material in the direction of the external force. After the material deforms to the maximum deformation amount, further increasing the external force will not cause further deformation of the material; the original thickness of the material refers to the thickness of the material when it is not affected by an external force.

[0239] For the buffer member 25, the compression ratio of the buffer member 25 reflects the deformation ability of the buffer member 25; if the compression ratio of the buffer member 25 is large, the deformation ability of the buffer member 25 is strong, and the buffer member 25 can provide a larger expansion space when the electrode assembly 22 expands; if the compression ratio of the buffer member 25 is small, the deformation ability of the buffer member 25 is weak, and the buffer can better limit the expansion deformation amount of the electrode assembly 22.

[0240] The compression ratio range of the buffer member 25 is 0-70%. For example, the compression ratio of the buffer member 25 can be 0, or 10%, 20%, 30%, 40%, 50%, 60%, 70% or other values.

[0241] Exemplarily, the compression ratio of the buffer member 25 can be 0. In this case, the buffer member 25 can be regarded as a rigid member. After the electrode assembly 22 expands and abuts against the buffer member 25, the electrode assembly 22 is restricted by the buffer member 25 and is not likely to expand further. At this time, the buffer member 25 can better inhibit the expansion of the electrode assembly 22. If it is necessary to release part of the expansion force of the electrode assembly 22, the distance between the electrode assembly 22 and the buffer member 25 needs to be controlled.

[0242] Exemplarily, the compression ratio of the buffer member 25 can be 35%. At this time, the buffer member 25 has a certain deformation ability. After the electrode assembly 22 expands and abuts against the buffer member 25, the electrode assembly 22 can continue to expand and compress the buffer member 25. When the buffer member 25 is compressed, it can provide resistance for the electrode assembly 22 and absorb part of the expansion force. The expansion deformation of the electrode assembly 22 stops after the buffer member 25 reaches its maximum deformation amount. In this setting, the buffer member 25 can not only release part of the expansion force of the electrode assembly 22, but also limit the expansion deformation amount of the electrode assembly 22. At this time, the distance between the electrode assembly 22 and the buffer member 25 can be reduced.

[0243] Exemplarily, the compression ratio of the buffer member 25 can be 70%. At this time, the buffer member 25 has a strong deformation ability. After the electrode assembly 22 expands and abuts against the buffer member 25, the electrode assembly 22 can continue to expand and compress the buffer member 25. When the buffer member 25 is compressed, it can provide resistance for the electrode assembly 22 and absorb part of the expansion force. The expansion deformation of the electrode assembly 22 stops after the buffer member 25 reaches its maximum deformation amount. In this setting, the buffer member 25 can better release the expansion force of the electrode assembly 22 and limit the expansion deformation amount of the electrode assembly 22. At this time, the distance between the electrode assembly 22 and the buffer member 25 can be further reduced.

[0244] This embodiment provides some compression ratio ranges of the buffer member 25 so that the buffer member 25 can not only provide space for the expansion of the electrode assembly 22, but also limit the expansion deformation amount of the electrode assembly 22.

[0245] In some embodiments where the buffer member 25 is an elastic member, the compression ratio range of the buffer member 25 is 30% - 50%. Exemplarily, the compression ratio of the buffer member 25 can be 30%, 35%, 40%, 45%, 50% or other values.

[0246] Exemplarily, the compression ratio of the buffer member 25 can be 30%. In this setting, the deformation ability of the buffer member 25 is weak, the ability of the buffer member 25 to release the expansion force is poor, and the ability to limit the expansion deformation of the electrode assembly 22 is strong.

[0247] For example, the compression ratio of the buffer member 25 can be 40%. In this setting, the deformation ability of the buffer member 25 is moderate. The buffer member 25 can not only release part of the expansion force of the electrode assembly 22, but also limit the expansion deformation amount of the electrode assembly 22.

[0248] For example, the compression ratio of the buffer member 25 can be 50%. In this setting, the deformation ability of the buffer member 25 is relatively strong. The buffer member 25 has a relatively strong ability to release the expansion force, while the ability to limit the expansion deformation of the electrode assembly 22 is relatively weak.

[0249] This embodiment further provides a compression ratio range of the buffer member 25, so that the buffer member 25 can not only provide space for the expansion of the electrode assembly 22, but also better limit the expansion deformation amount of the electrode assembly 22.

[0250] Reference Figure 10 、 Figure 11 In some embodiments, the buffer member 25 further includes a third part 255 connected to the first part 251 and the second part 252. The third part 255 is used to support the electrode assembly 22.

[0251] The third part 255 refers to the structure of the buffer member 25 located below the electrode assembly 22. The third part 255 is mainly used to support the electrode assembly 22, and is also used to insulate and separate the electrode assembly 22 from the housing 21, so as to reduce the short circuit caused by the contact between the electrode assembly 22 and the housing 21 or other structural members. The shape of the third part 255 can be circular, square or other shapes, and can also be set according to the shape of the electrode assembly 22 or the inner space 253. The material of the third part 255 can include plastics, rubbers, ceramics or other insulating materials.

[0252] The third part 255 is connected to the first part 251 and the second part 252. The third part 255 can be fixedly connected to the first part 251 and the second part 252 by welding, bonding or other means. The third part 255 can also be detachably connected to the first part 251 and the second part 252 by screwing, clamping, etc. The third part 255 can also be integrally formed with the first part 251 and the second part 252. In the case where the third part 255 is integrally formed with the first part 251 and the second part 252, the material of the third part 255 can also be the same as that of the first part 251 and the second part 252.

[0253] The connection of the third part 255 to the first part 251 and the second part 252 can also close the lower part of the inner space 253, so that the inner space 253 becomes a space with only an opening at the upper end. The electrolyte can be accommodated in the inner space 253. Since the buffer member 25 is accommodated in the accommodation cavity 211 and the buffer member 25 has a certain thickness, the liquid level of the electrolyte with the same volume in the inner space 253 can be higher than its liquid level in the accommodation cavity 211, so that the electrolyte can better infiltrate the electrode assembly 22.

[0254] In the current battery cell 20, a bottom support plate is usually provided to support the electrode assembly 22 through the bottom support plate, so as to insulate and separate the electrode assembly 22 from the housing 21.

[0255] Accordingly, a third part 255 is provided on the buffer member 25, and the third part 255 is connected to the first part 251 and the second part 252, so as to insulate and separate the electrode assembly 22 from the housing 21 through the third part 255. At this time, a bottom support plate may not be provided in the housing 21, so as to reduce the number of structural members in the accommodation cavity 211 and reduce the processing difficulty of the battery cell 20.

[0256] In this embodiment, the buffer member 25 includes a third part 255 to separate the electrode assembly 22 from the housing 21 through the third part 255, thereby reducing the short circuit caused by the contact between the electrode assembly 22 and the housing 21; at the same time, this setting can also save the bottom support plate in the battery cell 20, thereby reducing the number of components of the electrode assembly 22 and reducing the processing difficulty of the battery cell 20.

[0257] Reference Figure 10 、 Figure 11 In some embodiments, a through hole 2551 is formed in the third part 255.

[0258] The through hole 2551 refers to a hole structure formed in the third part 255. The through hole 2551 can be a straight hole, a stepped hole or other shaped hole structures. The through hole 2551 can be a round hole, a square hole or other shaped hole structures; the number of through holes 2551 can be one, or two or more.

[0259] In this embodiment, the through hole 2551 is provided in the third part 255 to facilitate the electrolyte to flow through the third part 255 and better wet other structures in the electrode assembly 22 and the housing 21.

[0260] In some embodiments, the battery cell 20 includes an electrode assembly 22, a housing 21 and a buffer member 25; the electrode assembly 22 includes a flat part 221 and a bent part 222.

[0261] The buffer member 25 includes two first parts 251 and two second parts 252. The two first parts 251 and the two second parts are connected end to end in sequence. A third part 255 is further connected below the first part 251 and the second part 252 to enclose an inner space 253 through the two first parts 251, the two second parts 252 and the third part 255, and the electrode assembly 22 is accommodated in the inner space 253.

[0262] The first part 251 includes a first surface 2511 opposite to the bending part 222. The first surface 2511 is an arc surface adapted to the bending part 222. The distance between the first surface 2511 and the side surface of the adjacent bending part 222 gradually increases from the connection position of the bending part 222 and the flat part 221 to the middle part of the bending part 222.

[0263] The second part 252 includes a second surface 2521 opposite to the flat part 221. The distance between the second surface 2521 and the adjacent flat part 221 gradually increases from the connection position of the flat part 221 and the bending part 222 to the middle part of the flat part 221. And the space between the first part 251 and the bending part 222 is smaller than the space between the second part 252 and the flat part 221.

[0264] In a second aspect, some embodiments of the present application further provide a battery 100, including the battery cell 20 provided by some embodiments of the first aspect. In such a battery 100, the electrode assembly 22 of the battery cell 20 is not easily broken due to expansion during use, so that the battery 100 can have high stability and good performance.

[0265] In a third aspect, some embodiments of the present application further provide an electrical device, including the battery 100 provided by some embodiments of the second aspect. In such an electrical device, the battery 100 has better stability, is not prone to a large drop in performance, and is not prone to thermal runaway leading to fires and other situations.

[0266] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered by the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, Comprising: A housing, within which there is an accommodation cavity; An electrode assembly, accommodated in the accommodation cavity, the electrode assembly including a flat portion and a bent portion connected to the flat portion; A buffer member, accommodated in the accommodation cavity and located between the electrode assembly and the housing, the buffer member including a first portion and a second portion connected to the first portion; The first portion faces the bent portion, the first portion includes a first surface facing the bent portion, and the first surface is an arc surface whose bending direction is the same as the bending direction of the side surface of the bent portion; The second portion faces the flat portion, in the arrangement direction of the flat portion and the bent portion, the thickness of the second portion gradually increases from the middle of the flat portion towards the edge of the flat portion, so that the surface of the second portion facing the flat portion gradually approaches the corresponding flat portion.

2. The battery cell according to claim 1, characterized in that, The bent portion is in contact with and abuts against the first surface.

3. The battery cell according to claim 1 or 2, characterized in that, The first portion and the second portion are connected end to end alternately in sequence and enclose an inner space for accommodating the electrode assembly; There is a first difference between the maximum length of the inner space and the maximum length of the electrode assembly, and there is a second difference between the maximum width of the inner space and the maximum width of the electrode assembly, and the first difference is less than or equal to the second difference.

4. The battery cell according to claim 3, wherein The range of the first difference is 0 to 2 mm.

5. The battery cell according to claim 3, characterized in that, The range of the first difference is 0 to 1 mm.

6. The battery cell according to claim 3, characterized in that, The minimum value of the second difference is 0.5 times the difference between the width of the accommodation cavity and the width of the electrode assembly, and the maximum value of the second difference is the difference between the width of the accommodation cavity and the width of the electrode assembly.

7. The battery cell according to claim 3, characterized in that, The minimum value of the second difference is greater than or equal to 2 mm.

8. The battery cell according to claim 1, wherein, The buffer member abuts against the connection portion between the bent portion and the flat portion at the connection position of the first portion and the second portion.

9. The battery cell according to claim 3, characterized in that, In the width direction of the electrode assembly, the range of the difference between the size of the inner space at the connection position of the first portion and the second portion and the width of the electrode assembly is 0 to 1 mm.

10. The battery cell according to claim 1, characterized in that, The second portion includes a second surface facing the flat portion, and the second surface is connected to the first surface and forms a connection portion at the connection position; From the connection portion to the middle of the first surface, the distance between the first surface and the bent portion remains unchanged or gradually increases; in the direction pointing from the connection portion to the second surface, the distance between the second surface and the flat portion gradually increases.

11. The battery cell according to claim 10, wherein, The maximum value of the distance between the second surface and the flat portion is greater than or equal to the maximum value of the distance between the first surface and the bent portion.

12. The battery cell according to claim 1, characterized in that, The height of the buffer member is less than or equal to the height of the electrode assembly.

13. The battery cell according to claim 12, characterized in that, The range of the difference between the height of the electrode assembly and the height of the buffer member is 0 to 5 mm.

14. The battery cell according to claim 1, characterized in that, The height of the buffer member is greater than or equal to the height of the electrode assembly.

15. The battery cell according to claim 14, wherein The range of the difference between the height of the buffer member and the height of the electrode assembly is 0 to 10 mm.

16. The battery cell according to claim 14, wherein, The range of the difference between the height of the buffer member and the height of the electrode assembly is 3 to 10 mm.

17. The battery cell according to claim 1, wherein, The buffer member abuts against the housing.

18. The battery cell according to claim 1, characterized in that, The buffer member is disposed at an interval from the housing, and the distance between the buffer member and the housing ranges from 0 to 0.5 mm.

19. The battery cell according to claim 1, wherein, The number of the electrode assemblies is at least two, and the electrode assemblies are arranged along the width direction of the battery cell, and two adjacent flat portions are in contact with each other; The first portion includes at least two first surfaces arranged along the width direction of the battery cell, and each of the first surfaces is opposite to an adjacent bending portion.

20. The battery cell according to claim 1, wherein Partition grooves are provided on the second portion, and the partition grooves are used for partitioning the second portion into two sub-portions spaced apart along the length direction of the battery cell.

21. The battery cell according to claim 20, characterized in that, Chamfers are provided on the edges of one side of either of the two sub-portions facing the other.

22. The battery cell according to claim 1, characterized in that, The buffer member is an elastic member.

23. The battery cell according to claim 22, wherein, The compression ratio range of the buffer member is from 0 to 70%.

24. The battery cell according to claim 22 or 23, characterized in that, The compression ratio range of the buffer member is from 30% to 50%.

25. The battery cell according to claim 1, characterized in that, The buffer member further includes a third portion connected to the first portion and the second portion, and the third portion is used for supporting the electrode assembly.

26. The battery cell according to claim 25, wherein Through holes are formed in the third portion.

27. A battery, characterized in that, Comprising a battery cell according to any one of claims 1-26.

28. An electrical device, characterized in that, Comprising a battery according to claim 27.

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