Battery cell, battery, and electrical device

Abstract

The present application provides a battery cell, a battery, and an electrical device. The battery cell includes a housing and an electrode assembly housed within the housing. The housing includes a first plate and a second plate, the second plate and the first plate are provided to intersect, the first plate includes a first inner wall surface facing the electrode assembly, and the second plate includes a second inner wall surface facing the electrode assembly. The housing includes a third inner wall surface connecting the first inner wall surface and the second inner wall surface, at least a part of the third inner wall surface defines a first recessed groove, and in the thickness direction of the first plate, the first recessed groove is recessed away from the electrode assembly with respect to the first inner wall surface, and a part of the projection of the electrode assembly onto the first plate overlaps with the first recessed groove.

Description

Technical Field

[0001] (Cross - reference to Related Applications) This application claims the priority of International Patent Application PCT / CN2022 / 130408, titled "Case, Battery Cell, Battery and Electrical Device", filed on November 7, 2022, and all the contents of the said application are incorporated herein by reference.

[0002] This application relates to the field of batteries, and more specifically, to battery cells, batteries and electrical devices.

Background Art

[0003] Battery cells are widely applied to electronic devices such as mobile phones, laptops, electric motorcycles, electric vehicles, electric airplanes, electric propulsion ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools.

[0004] In the development of battery technology, how to improve the reliability of battery cells is one of the research directions in battery technology.

Summary of the Invention

[0005] This application provides a battery cell, a battery and an electrical device that can enhance reliability.

[0006] In a first aspect, an embodiment of this application provides a battery cell including a housing and an electrode assembly housed in the housing. The housing includes a first plate and a second plate, the second plate and the first plate are provided intersectingly, the first plate includes a first inner wall surface facing the electrode assembly, and the second plate includes a second inner wall surface facing the electrode assembly. The housing includes a third inner wall surface connecting the first inner wall surface and the second inner wall surface, at least a part of the third inner wall surface defines a first recessed groove for retreat, in the thickness direction of the first plate, the first recessed groove for retreat is recessed away from the electrode assembly with respect to the first inner wall surface, and a part of the projection of the electrode assembly on the first plate overlaps with the first recessed groove for retreat.

[0007] In the embodiments of the present application, the electrode assembly is retracted by the first retraction concave groove. When the battery cell is subjected to an external impact, the risk that the electrode assembly is pressed by the intersection of the first plate and the second plate is reduced, the shedding of the active material of the electrode assembly is reduced, the attenuation of the capacity of the battery cell is delayed, and the reliability of the battery cell can be improved. For example, the first retraction concave groove hides the concavo-convex region formed at the intersection of the first plate and the second plate, increases the distance between the concavo-convex region and the electrode assembly, and can reduce the risk that the electrode assembly is pressed by the concavo-convex region.

[0008] In some embodiments, the first inner wall surface is used to support the electrode assembly.

[0009] By supporting the electrode assembly, the first inner wall surface reduces the risk that the corner of the electrode assembly falls into the first retraction concave groove, increases the pitch in the thickness direction of the first plate between the intersection of the first plate and the second plate and the electrode assembly, reduces the risk that the electrode assembly is pressed by the intersection of the first plate and the second plate, reduces the shedding of the active material of the electrode assembly, and can improve the reliability of the battery cell.

[0010] In some embodiments, the electrode assembly includes a first electrode plate and a second electrode plate with opposite polarities. The first electrode plate and the second electrode plate both include a straight layer provided opposite to the second plate. The plurality of straight layers are stacked and provided along the first direction. Both ends of the first retraction concave groove in the second direction exceed the straight layer. The thickness direction of the first plate, the first direction, and the second direction are perpendicular to each other, and the first direction is parallel to the thickness direction of the second plate.

[0011] Since both ends of the first retraction concave groove in the second direction exceed the straight layer, the straight layer is retracted as much as possible, the minimum distance between the intersection of the first plate and the second plate and the straight layer closest to the second plate is increased, and when the battery cell is subjected to an external impact, the risk that the straight layer is pressed by the intersection of the first plate and the second plate is reduced, the shedding of the active material of the straight layer is reduced, and the reliability of the battery cell can be improved.

[0012] In some embodiments, the housing further includes a third plate, the third plate being located on a side of the electrode assembly in the second direction and connected to the first plate and the second plate, and the first recess and the third plate are spaced apart in the second direction.

[0013] By separating the boundary between the first plate, the second plate, and the third plate from the first retraction groove by a certain distance in the second direction, the risk of the first retraction groove extending to the boundary between the three plates is reduced, stress concentration at the boundary between the three plates is alleviated, and the strength and reliability of the housing are improved.

[0014] In some embodiments, the first electrode plate and the second electrode plate are wound and provided, the electrode assembly includes a straight region and a folded region, the folded region is connected to an end of the straight region in the second direction, and the plurality of straight layers are located in the straight region.

[0015] In some embodiments, the housing further includes a third plate, the third plate being located on a side of the electrode assembly in the second direction and connected to the first and second plates. The third plate further includes a fourth inner wall surface facing the electrode assembly. The housing further includes a fifth inner wall surface connecting the first inner wall surface and the fourth inner wall surface, and at least a portion of the fifth inner wall surface defines a second recessed groove, the second recessed groove being recessed relative to the first inner wall surface toward a side away from the electrode assembly in the thickness direction of the first plate. In the thickness direction of the first plate, at least a portion of the projection of the bending region onto the first plate overlaps with the second recessed groove.

[0016] The second retraction groove retracts the bending area, reducing the risk of the bending area being pressed by the intersection of the first plate and the third plate when the battery cell is subjected to external impact, thereby reducing the loss of active material from the electrode assembly, delaying the decay of the battery cell capacity, and improving the reliability of the battery cell.

[0017] In some embodiments, the housing includes two second plates provided opposite to each other along a first direction and two third plates provided opposite to each other along a second direction. The second inner wall surface of each second plate is connected to the first inner wall surface by at least one third inner wall surface, and the fourth inner wall surface of each third plate is connected to the first inner wall surface by at least one fifth inner wall surface.

[0018] By providing a first recessed groove and a second recessed groove around the first plate, even when the position of the electrode assembly is displaced, the electrode assembly can still be effectively retracted, and the risk of the corners of the electrode assembly being pressed can be reduced.

[0019] In some embodiments, in the first direction, the second recessed groove and the second plate are provided at an interval. By keeping a certain distance between the boundary portion of the first plate, the second plate and the third plate and the second recessed groove in the first direction, the risk of the second recessed groove extending to the boundary portion of the three plates is reduced, the stress concentration at the boundary portion of the three plates is alleviated, and the strength and reliability of the housing are enhanced.

[0020] In some embodiments, both ends of the first recessed groove communicate with two second recessed grooves respectively. By communicating the first recessed groove and the second recessed groove, the structure of the mold can be simplified and the forming efficiency can be improved.

[0021] In some embodiments, there are a plurality of electrode assemblies, and the plurality of electrode assemblies are stacked and provided along the first direction. In the thickness direction of the first plate, the projection of the bending region of each electrode assembly onto the first plate all has a portion overlapping with the second recessed groove.

[0022] One second recessed groove can retract the bending regions of a plurality of electrode assemblies simultaneously. When the battery cell is subjected to an external impact, the shedding of the active material of the electrode assembly can be reduced, and the reliability of the battery cell can be enhanced.

[0023] In some embodiments, there are a plurality of electrode assemblies, and the plurality of electrode assemblies are provided by being stacked along a first direction. A plurality of fifth inner wall surfaces provided at intervals along the first direction connect the first inner wall surface and the fourth inner wall surface, and a plurality of second retreat grooves are defined by the plurality of fifth inner wall surfaces. In the thickness direction of the first plate, each second retreat groove has a portion overlapping with the projection of the bending region of at least one electrode assembly onto the first plate.

[0024] Since the bending regions of the plurality of electrode assemblies are provided at intervals along the first direction, a plurality of second retreat grooves separated by intervals can be provided to retreat the bending regions of the plurality of electrode assemblies. In this way, the extension length of a single second retreat groove can be shortened, and the forming difficulty of the second retreat groove can be reduced.

[0025] In some embodiments, the electrode assembly includes a plurality of first electrode plates, the plurality of first electrode plates are provided by being stacked along the first direction, and each first electrode plate includes one straight layer. The housing includes two first plates provided opposite to each other along the thickness direction of the first plate and two second plates provided opposite to each other along the first direction, and the first plates and the second plates are alternately provided in the circumferential direction of the housing. Both ends of the first inner wall surface of each first plate in the first direction are respectively connected to the second inner wall surfaces of the two second plates by two third inner wall surfaces.

[0026] The first retreat groove retreats the first electrode plate closest to one second plate and the first electrode plate closest to the other second plate. When the battery cell is subjected to an impact in the thickness direction of the first plate, the risk that the first electrode plate is pressed by the intersection of the first plate and the second plate can be reduced, the shedding of the active material can be reduced, the attenuation of the capacity of the battery cell can be delayed, and the reliability of the battery cell can be improved.

[0027] In some embodiments, a third retraction groove communicating with the first retraction groove is further defined by the third inner wall surface. In the thickness direction of the second plate, the third retraction groove is recessed toward the side away from the electrode assembly with respect to the second inner wall surface. In the thickness direction of the second plate, a part of the projection of the electrode assembly onto the second plate overlaps with the third retraction groove.

[0028] When the battery cell is subjected to an impact in the thickness direction of the second plate, the third retraction groove can reduce the risk of the first electrode plate being pressed by the intersection of the first plate and the second plate, reduce the shedding of the active material, delay the attenuation of the capacity of the battery cell, and enhance the reliability of the battery cell.

[0029] In some embodiments, the third inner wall surface includes a first surface and a second surface. The first surface is a curved surface and is connected to the second inner wall surface. The second surface connects the first surface and the first inner wall surface. The first retraction groove is defined by at least a part of the first surface and the second surface.

[0030] By providing the arc-shaped first surface, a substantially fillet structure is formed at the intersection of the first plate and the second plate, thereby dispersing stress during the forming process, reducing stress concentration, and enhancing the reliability of the housing. At least a part of the first surface is hidden in the first retraction groove. Thus, when the battery cell is subjected to an external impact, the risk of the electrode assembly being pressed by the first surface can be reduced, the shedding of the active material of the electrode assembly can be reduced, the attenuation of the capacity of the battery cell can be delayed, and the reliability of the battery cell can be enhanced.

[0031] In some embodiments, the first surface includes a first region and a second region. The first region protrudes from the side facing the electrode assembly of the first inner wall surface in the thickness direction of the first plate and is connected to the second inner wall surface. The second region connects the first region and the second surface. The first retraction groove is defined by the second region and the second surface.

[0032] The isolation member of the electrode assembly can play a role of support and buffer to a certain extent. Even if the first surface has a first region protruding from the first inner wall surface, the isolation member can isolate the first region from the electrode plate of the electrode assembly to a certain extent, reduce the shedding of the active material of the electrode assembly, and improve the reliability of the battery cell. In the embodiments of the present application, it only needs to hide the second region in the first retraction groove, reduce the requirements for the depth of the first retraction groove, and reduce the forming difficulty.

[0033] In some embodiments, the first surface is an arc surface. Both ends of the first surface are in contact with the second inner wall surface and the second surface respectively. The radius of the first surface is R. In the thickness direction of the first plate, the dimension of the region of the first surface located in the first retraction groove is d, and 0.1R≤d≤R.

[0034] In the embodiments of the present application, by limiting d to be not less than 0.1R, the arc surface hidden in the first retraction groove has a large arc length, so that the electrode assembly can be effectively retracted, the risk that the electrode assembly is pressed by the first surface is reduced, the shedding of the active material of the electrode assembly is reduced, the attenuation of the capacity of the battery cell is delayed, and the reliability of the battery cell is improved. In the embodiments of the present application, by limiting d to be not more than R, the maximum depth of the first retraction groove is limited, the loss of the strength of the housing is reduced, and the reliability of the battery cell is improved.

[0035] In some embodiments, 0.3R≤d≤0.9R, and the reliability of the battery cell can be further improved.

[0036] In some embodiments, the second surface includes a third region and a fourth region provided intersectingly. The third region is connected to the first surface and is parallel to the first inner wall surface. The fourth region connects the third region and the first inner wall surface. By providing the third region parallel to the first inner wall surface, the uniformity of the force received in the pressing and forming process of the first retraction groove can be improved.

[0037] In some embodiments, in the thickness direction of the second plate, the maximum dimension w of the first retraction concave groove is 1 mm to 10 mm.

[0038] In the embodiments of the present application, by limiting w to be 1 mm or more, the retraction space is enlarged, the risk that the electrode assembly is pressed by the intersection of the first plate and the second plate is reduced, and the reliability is improved. In the embodiments of the present application, by limiting w to be 10 mm or less, in the pressing and forming process of the first retraction concave groove, the flow of the material is reduced, the forming difficulty of the first retraction concave groove is reduced, and the flatness of the first plate is improved.

[0039] In some embodiments, w is 3 mm to 8 mm.

[0040] In some embodiments, the maximum hardness of the portion of the housing corresponding to the first retraction concave groove in the thickness direction of the first plate is greater than the maximum hardness of the portion corresponding to the first inner wall surface of the first plate.

[0041] The portion of the housing corresponding to the first retraction concave groove in the thickness direction of the first plate can be abbreviated as the concave groove portion. Since the minimum thickness of the concave groove portion may be reduced by the opening of the first retraction concave groove, by increasing the maximum hardness of the concave groove portion, the damage to the structural strength caused by the opening of the first retraction concave groove can be reduced, the risk that the concave groove portion cracks can be reduced, and the reliability of the battery cell can be improved.

[0042] In some embodiments, the third inner wall surface is on the side closer to the first inner wall surface of the plane where the second inner wall surface is located.

[0043] The third inner wall surface can be formed by the pressing of the external die head. After the third inner wall surface is formed, the external die head can be withdrawn along the thickness direction of the first plate. In the embodiments of the present application, the third inner wall surface is provided on the side closer to the first inner wall surface of the plane where the second inner wall surface is located, the interference of the second inner wall surface with respect to the external die head can be reduced, and the die head can be easily withdrawn.

[0044] In some embodiments, the housing includes a case and an end cap, the case has an opening, the end cap covers the opening, and the case includes a first plate and a second plate.

[0045] In a second aspect, an embodiment of the present application provides a battery including a plurality of battery cells provided by any one of the embodiments of the first aspect.

[0046] In a third aspect, an embodiment of the present application provides an electrical device including a battery provided by any one of the embodiments of the first aspect for providing electrical energy.

Brief Description of the Drawings

[0047] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly described below. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative efforts.

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Embodiments for Carrying Out the Invention

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, hereinafter, with reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly described. It is obvious that the described embodiments are only a part of the embodiments of the present application, not all of them. Based on the embodiments of the present application, all other embodiments obtained on the premise that those skilled in the art do not make creative efforts all belong to the protection scope of the present application.

[0049] Unless otherwise defined, all technical and scientific terms used in this application shall have the same meaning as commonly understood by those skilled in the art. The terms used in the specification of this application are merely for the purpose of explaining specific embodiments and are not intended to limit this application. The terms "comprising" and "having" and any variations thereof in the specification, claims, and description of the above drawings of this application are intended to cover a non-exclusive "comprising". The terms such as "first" and "second" in the specification, claims, and above drawings of this application are for distinguishing different objects and not for explaining a specific order or primary-secondary relationship.

[0050] When referring to "embodiments" in this application, it means that specific features, structures, or characteristics described in accordance with the embodiments may be included in at least one embodiment of this application. This phrase described in each part of the specification does not necessarily refer to the same embodiment, nor is it an exclusive, separate, or alternative embodiment that is mutually exclusive with other embodiments.

[0051] In the description of this application, unless specifically defined and limited, the terms "attach", "connect", "join", and "couple" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection, a direct connection, an indirect connection through an intermediate medium, or a communication inside two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific situation.

[0052] The term "and / or" in this application is merely for describing the relationship of related objects and indicates that three relationships may exist. For example, A and / or B can represent three cases: A alone, the combination of A and B, and B alone. Also, the character " / " in this application generally represents that the related objects before and after are in an "or" relationship.

[0053] In the embodiments of the present application, the same reference numerals represent the same components. For the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the dimensions such as the thickness, length, and width of each member in the embodiments of the present application shown in the drawings, and the dimensions such as the overall thickness, length, and width of the integrated device are merely exemplary and do not impose any limitation on the present application.

[0054] In the present application, "a plurality" means two or more (including two).

[0055] In the embodiments of the present application, the battery cell may be a secondary battery, and the secondary battery refers to a battery cell that can continue to be used by activating the active material by charging after the battery cell discharges.

[0056] The battery cell can include, but is not limited to, a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0057] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, or a battery cell of other shapes. The prismatic battery cell includes a flat prismatic battery cell, a blade-shaped battery cell, and a polygonal battery. The polygonal battery is, for example, a hexagonal battery, etc., and is not particularly limited in the present application.

[0058] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide a higher voltage and capacity.

[0059] In some embodiments, the battery may be a battery module. When there are a plurality of battery cells, the plurality of battery cells are arranged and fixed to form a battery module.

[0060] In some embodiments, the battery may be a battery pack, which includes a housing and battery cells, and the battery cells or battery modules are housed in the housing.

[0061] In some embodiments, the housing can be part of the chassis structure of a vehicle. For example, part of the housing can be at least part of the vehicle's floorboard, or part of the housing can be at least part of the vehicle's cross beams and longitudinal beams.

[0062] In some embodiments, the battery may be an energy storage device. The energy storage device includes an energy storage container, an energy storage electrical cabinet, etc.

[0063] A battery cell generally includes an electrode assembly and a housing, and the electrode assembly is housed in the housing. The electrode assembly includes a positive electrode, a negative electrode, and a separator member. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are repeatedly inserted and detached between the positive electrode and the negative electrode. The separator member is provided between the positive electrode and the negative electrode, which can reduce the risk of short circuit between the positive and negative electrodes and at the same time allow active ions to pass through.

[0064] The housing is used to package members such as the electrode assembly and the electrolyte. The housing can be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), or a composite metal housing (such as a copper-aluminum composite housing), etc.

[0065] During the molding process of the housing, the intersection of the two plates of the housing may become uneven due to the flow of the material. When the battery cell is subjected to an external impact, the electrode assembly is easily pressed by the intersection of the two plates, resulting in a risk of the active material of the electrode assembly falling off and causing reliability problems.

[0066] In some embodiments, usually, a support plate is provided inside the housing. By supporting the electrode assembly, the support plate can increase the distance between the electrode assembly and the intersection of the two plates, and reduce the risk of the electrode assembly being pressed. However, the support plate occupies the internal space of the housing, not only reducing the density of the battery cells, but also complicating the assembly process of the battery cells and affecting the manufacturing cost of the battery cells.

[0067] In view of this, the embodiments of the present application provide a technical solution of providing a retraction concave groove at the intersection of the two plates of the housing, increasing the distance between the convex and concave region of the housing and the electrode assembly, reducing the risk of the electrode assembly being pressed by the housing, reducing the shedding of the active material of the electrode assembly, delaying the attenuation of the capacity of the battery cell, and enhancing the reliability of the battery cell. Also, according to the technical solution of the present application, the support plate can be omitted, the number of parts of the battery cell can be reduced, the structure of the battery cell can be simplified, and the energy density of the battery cell can be improved.

[0068] The battery cell described in the embodiments of the present application is applicable to a battery and an electrical device using the battery.

[0069] The battery cell, battery and electrical device disclosed in the embodiments of the present application can be used in an electrical device using the battery as a power source or various energy storage systems using the battery as an energy storage element. The electrical device may be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, a power tool, an electric bicycle, an electric vehicle, a ship, an aircraft, etc. The electric toy can include fixed or mobile electric toys such as a game console, an electric vehicle toy, an electric propulsion ship toy and an electric airplane toy, and the aircraft can include an airplane, a rocket, a space shuttle and a spaceship, etc.

[0070] In the following embodiments, for the sake of easy explanation, the case where the electrical device is a vehicle will be described as an example.

[0071] FIG. 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.

[0072] As shown in FIG. 1, a battery 2 is provided inside the vehicle 1, and the battery 2 may be provided at the bottom, front, or rear of the vehicle 1. The battery 2 can be used to supply power to the vehicle 1. For example, the battery 2 can be used as the operating power source of the vehicle 1.

[0073] The vehicle 1 may further include a controller 3 and a motor 4. The controller 3 is used to control the battery 2 to supply power to the motor 4. For example, it is used to meet the needs of the operating power during the start, navigation, and driving of the vehicle 1.

[0074] In some embodiments of the present application, the battery 2 can not only be used as the operating power source of the vehicle 1, but also as the driving power source of the vehicle 1 to provide driving power to the vehicle 1 instead of gasoline or natural gas, or instead of a part of them.

[0075] FIG. 2 is an exploded schematic view of a battery provided according to some embodiments of the present application. As shown in FIG. 2, the battery 2 includes a housing 5 and battery cells 6 housed in the housing 5.

[0076] The housing 5 is used to house the battery cells 6, and the housing 5 may have various structures. In some embodiments, the housing 5 can include a first housing part 5a and a second housing part 5b. The first housing part 5a and the second housing part 5b cover each other, and the first housing part 5a and the second housing part 5b together define a storage space 5c for housing the battery cells 6. The second housing part 5b may have a hollow structure with an opening at one end. The first housing part 5a has a plate-like structure. The first housing part 5a covers the opening side of the second housing part 5b so as to form the housing 5 having the storage space 5c. The first housing part 5a and the second housing part 5b may both have a hollow structure with an opening on one side, and the opening side of the first housing part 5a covers the opening side of the second housing part 5b so as to form the housing 5 having the storage space 5c. Of course, the first housing part 5a and the second housing part 5b may have various shapes such as a cylinder or a cuboid.

[0077] In order to enhance the sealing performance after connecting the first housing portion 5a and the second housing portion 5b, a sealing member such as a sealant or a sealing ring may be provided between the first housing portion 5a and the second housing portion 5b.

[0078] If it is assumed that the first housing portion 5a is covered by the top portion of the second housing portion 5b, the first housing portion 5a may be referred to as an upper housing lid, and the second housing portion 5b may be referred to as a lower housing.

[0079] In the battery 2, the battery cells 6 may be one or a plurality. If there are a plurality of battery cells 6, the plurality of battery cells 6 may be connected in series, in parallel, or in series-parallel. Series-parallel connection means that both series connection and parallel connection are included in the plurality of battery cells 6. The plurality of battery cells 6 may be directly connected in series, in parallel, or in series-parallel, and then the whole formed by the plurality of battery cells 6 may be housed in the housing 5. Of course, the plurality of battery cells 6 may first be connected in series, in parallel, or in series-parallel to form a battery module, and then the plurality of battery modules may be further connected in series, in parallel, or in series-parallel to form one whole and housed in the housing 5.

[0080] The battery cell 6 may be the smallest unit constituting the battery.

[0081] FIG. 3 is an exploded schematic view of a battery cell provided according to some embodiments of the present application.

[0082] As shown in FIG. 3, in some embodiments, the battery cell 6 includes a housing 20 and an electrode assembly 10 housed in the housing 20.

[0083] The electrode assembly 10 includes a positive electrode and a negative electrode. During the charge and discharge process of the battery cell 6, active ions (e.g., lithium ions) are repeatedly inserted and detached between the positive electrode and the negative electrode. Optionally, the electrode assembly 10 further includes a separator provided between the positive electrode and the negative electrode, and the separator can reduce the risk of short circuit between the positive and negative electrodes and at the same time allow active ions to pass through.

[0084] In some embodiments, the positive electrode may be a positive electrode plate, and the positive electrode plate may include a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector.

[0085] As an example, the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode active material layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0086] As an example, the positive electrode current collector can employ a metal foil or a composite current collector. For example, as the metal foil, stainless steel, copper, aluminum, nickel, fired carbon, carbon, nickel, titanium, aluminum surface-treated with silver or stainless steel, etc. can be employed. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base (such as a base of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0087] As an example, the positive electrode active material layer contains a positive electrode active material, and the positive electrode active material can include at least one of materials such as lithium-containing phosphates, lithium transition metal oxides, and modified compounds thereof. However, the present application is not limited to these materials, and other conventional materials used as the positive electrode active material layer of the battery may also be used. These positive electrode active material layers may be used alone or in combination of two or more. Examples of lithium-containing phosphates can include, but are not limited to, lithium iron phosphate (e.g., LiFePO4 (which may also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon. Examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which may also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which may also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which may also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which may also be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which may also be abbreviated as NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.80 Co 0.15 Al 0.05It can include, but is not limited to, at least one of O2) and its modified compounds, etc.

[0088] In some embodiments, the positive electrode can employ a foamed metal. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When the foamed metal is used as the positive electrode, it is not necessary to provide a positive electrode active material layer on the surface of the foamed metal. Of course, a positive electrode active material layer may also be provided. As an example, a lithium source material, potassium metal or sodium metal may be further filled or / and deposited in the foamed metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0089] In some embodiments, the negative electrode may be a negative electrode plate, and the negative electrode plate can include a negative electrode current collector.

[0090] As an example, the negative electrode current collector can employ a metal foil, foamed metal or composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, copper, aluminum, nickel, fired carbon, carbon, nickel or titanium, etc. can be adopted. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as substrates of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0091] As an example, the negative electrode plate can include a negative electrode current collector and a negative electrode active material provided on at least one surface of the negative electrode current collector.

[0092] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is provided on either one or both of the two opposing surfaces of the negative electrode current collector.

[0093] As an example, as the type of the negative electrode active material, a negative electrode active material for a battery cell known in the art can be adopted. As an example, the negative electrode active material can include at least one of materials such as artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material can be selected from at least one of silicon alone, silicon oxygen compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. The tin-based material can be selected from at least one of tin alone, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials used as the negative electrode active material of the battery may be used. These negative electrode active materials may be used alone or in combination of two or more.

[0094] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0095] In some embodiments, the isolation member includes a separator. In the present application, the type of the separator is not particularly limited, and any known separator with a porous structure having good chemical stability and mechanical stability can be selected.

[0096] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator may be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, and are not particularly limited. The isolation member may be an independent member located between the positive and negative electrodes, or may be attached to the surfaces of the positive and negative electrodes.

[0097] In some embodiments, the isolation member is a solid electrolyte. The solid electrolyte is provided between the positive electrode and the negative electrode, and simultaneously plays a role of transporting ions and isolating the positive and negative electrodes.

[0098] In some embodiments, the battery cell further includes an electrolyte, which plays a role in conducting ions between the positive and negative electrodes. In the present application, the type of the electrolyte is not specifically limited and can be selected according to needs. The electrolyte may be liquid, gel-like or solid.

[0099] The liquid electrolyte includes an electrolyte salt and a solvent.

[0100] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate and lithium tetrafluorooxalatophosphate.

[0101] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent can also be an ether-based solvent. The ether-based solvent can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, and crown ether.

[0102] The gel-state electrolyte includes a polymer as the electrolyte and a skeletal network combined with a lithium salt which is an ionic liquid.

[0103] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0104] As an example, the polymer solid electrolyte may be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monovalent ion polymer, lithium salt which is a polyionic liquid, cellulose, etc.

[0105] As an example, the inorganic solid electrolyte may be one or more of an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superionic conductor (lithium germanium phosphorus sulfide, thiargyrite), amorphous sulfide), and a halide solid electrolyte, a nitride solid electrolyte, and a hydride solid electrolyte.

[0106] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0107] In some embodiments, the electrode assembly 10 has a wound structure. The positive electrode plate and the negative electrode plate are wound into the wound structure.

[0108] In some embodiments, the electrode assembly 10 has a laminated structure.

[0109] As an example, a plurality of positive electrode plates and a plurality of negative electrode plates may be provided respectively, and the plurality of positive electrode plates and the plurality of negative electrode plates are alternately laminated.

[0110] As an example, a plurality of positive electrode plates may be provided, the negative electrode plate is folded to form a plurality of folded portions that are laminated, and one positive electrode plate is sandwiched between adjacent folded portions.

[0111] As an example, both the positive electrode plate and the negative electrode plate are folded to form a plurality of folded portions that are laminated.

[0112] As an example, a plurality of separator members may be provided, and each is provided between any adjacent positive electrode plate or negative electrode plate.

[0113] As an example, the separator members may be provided continuously and are provided between any adjacent positive electrode plates or negative electrode plates in a folded or wound form.

[0114] In some embodiments, the shape of the electrode assembly 10 may be cylindrical, flat, polygonal, or the like.

[0115] In some embodiments, the electrode assembly 10 is provided with tabs, and the tabs can conduct current out of the electrode assembly 10. The tabs include a positive tab and a negative tab.

[0116] In some embodiments, the housing 20 includes a case 30 and an end cap 40. The case 30 has an opening, and the end cap 40 is used to cover the opening.

[0117] The case 30 is a member for forming the internal cavity of the battery cell 6 in accordance with the end cap 40, and the formed internal cavity can be used to house the electrode assembly 10, the electrolyte, and other members.

[0118] The case 30 and the end cap 40 may be independent members. Exemplarily, an opening can be provided in the case 30, and the internal cavity of the battery cell 6 is formed by covering the opening with the end cap 40 at the opening.

[0119] The housing 30 may have various shapes and dimensions such as, for example, a rectangular parallelepiped shape, a cylindrical shape, a hexagonal prism shape, etc. Specifically, the shape of the housing 30 can be determined according to the specific shape and dimensions of the electrode assembly 10. The material of the case 30 may be plural, for example, the material of the case 30 includes, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0120] The shape of the end cap 40 can be adapted to the shape of the case 30 so as to match the case 30. The material of the end cap 40 and the material of the case 30 may be the same or different. Optionally, the end cap 40 can be manufactured from a material having a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.). In this way, when the end cap 40 is pressed and collided, it is less likely to be distorted, the battery cell 6 can have higher structural strength, and the reliability can also be improved.

[0121] The end cap 40 is connected to the case 30 by welding, adhesion, clamping or other means.

[0122] The case 30 may be open at one end or both ends. In some examples, the case 30 may have a structure that is open on one side, and one end cap 40 is provided to cover the case 30. In another example, the case 30 may have a structure that is open on both sides, and two end caps 40 are provided, and the two end caps 40 respectively cover the two openings of the case 30.

[0123] In some embodiments, the battery cell 6 includes an electrode terminal 50. The electrode terminal 50 is electrically connected to the tab to output or input the electrical energy of the battery cell 6.

[0124] In some embodiments, the battery cell 6 further includes an adapter 60, and the adapter 60 connects the tab and the electrode terminal 50.

[0125] In some embodiments, the battery cell 6 further includes an insulating member 70 provided in the housing 20. The insulating member 70 has a storage cavity, and at least a part of the electrode assembly 10 is stored in the storage cavity. The insulating member 70 can be used to isolate the electrode assembly 10 and the case 30 to insulate them.

[0126] In some embodiments, the insulating member 70 is formed by folding an insulating sheet.

[0127] FIG. 4 is a schematic cross-sectional view of a battery cell provided by some embodiments of the present application. FIG. 5 is an enlarged schematic view of the circular frame portion of FIG. 4. FIG. 6 is a schematic top view of the case of the battery cell provided by some embodiments of the present application. The dotted line is the contour of the projection of the electrode assembly onto the case. FIG. 7 is a schematic view of the electrode assembly of the battery cell provided by some embodiments of the present application. FIG. 8 is an enlarged schematic view of the box portion of FIG. 6.

[0128] Referring to FIGS. 4 to 8 together, an embodiment of the present application provides a battery cell 6 including a housing 20 and an electrode assembly 10 housed in the housing 20. The housing 20 includes a first plate 31 and a second plate 32. The second plate 32 and the first plate 31 are provided intersecting each other. The first plate 31 includes a first inner wall surface 311 facing the electrode assembly 10, and the second plate 32 includes a second inner wall surface 321 facing the electrode assembly 10. The housing 20 includes a third inner wall surface 34 connecting the first inner wall surface 311 and the second inner wall surface 321. At least a part of the third inner wall surface 34 defines a first recessed groove 35. In the thickness direction Z of the first plate, the first recessed groove 35 is recessed away from the electrode assembly 10 with respect to the first inner wall surface 311, and a part of the projection of the electrode assembly 10 onto the first plate 31 overlaps with the first recessed groove 35.

[0129] The housing 20 may house one electrode assembly 10 or may house a plurality of electrode assemblies 10.

[0130] The first plate 31 and the second plate 32 are provided at a predetermined angle, and the angle between the first plate 31 and the second plate 32 may be an acute angle, a right angle, or an obtuse angle.

[0131] Exemplarily, the plane where the first inner wall surface 311 is located intersects with the plane where the second inner wall surface 321 is located.

[0132] The first plate 31 may be one or a plurality, and the second plate 32 may be one or a plurality. Exemplarily, there are two second plates 32, and the two second plates 32 are respectively connected to both ends of the first plate 31. The second inner wall surface 321 of at least one second plate 32 is connected to the first inner wall surface 311 by the third inner wall surface 34.

[0133] Exemplarily, the plane where the first inner wall surface 311 is located is the virtual first reference plane S1, and the electrode assembly 10 is located on one side of the first reference plane S1. The first reference plane S1 can be used to define the boundary of the first retraction concave groove 35. The opening of the first retraction concave groove 35 is located on the first reference plane S1.

[0134] In some examples, the first retraction concave groove 35 can be defined by a part of the third inner wall surface 34, that is, the groove wall surface of the first retraction concave groove 35 is a part of the third inner wall surface 34, and another part of the third inner wall surface 34 can be located outside the first retraction concave groove 35 (for example, located on the side of the electrode assembly 10 facing the first reference plane S1). In an alternative embodiment, the first retraction concave groove 35 can be defined by the entire third inner wall surface 34, that is, the groove wall surface of the first retraction concave groove 35 is the third inner wall surface 34.

[0135] In the thickness direction Z of the first plate, a part of the projection of the electrode assembly 10 onto the first plate 31 overlaps with the first retraction concave groove 35.

[0136] In the embodiment of the present application, when the electrode assembly 10 is retracted by the first retraction concave groove 35 and the battery cell 6 is subjected to an external impact, the risk that the electrode assembly 10 is pressed by the intersection of the first plate 31 and the second plate 32 can be reduced, the shedding of the active material of the electrode assembly 10 can be reduced, the attenuation of the capacity of the battery cell 6 can be delayed, and the reliability of the battery cell 6 can be improved.

[0137] The first recessed groove 35 can hide the uneven region formed at the intersection of the first plate 31 and the second plate 32, increase the distance between the uneven region and the electrode assembly 10, and reduce the risk that the electrode assembly 10 is pressed by the uneven region. Further, by providing the first recessed groove 35, the support plate in a normal battery cell 6 can be omitted, the number of components of the battery cell 6 can be reduced, the structure of the battery cell 6 can be simplified, and the energy density of the battery cell 6 can be improved.

[0138] In some embodiments, the housing 20 includes a case 30 and an end cap 40. The case 30 has an opening, and the end cap 40 covers the opening. The case 30 includes a first plate 31 and a second plate 32.

[0139] In some embodiments, the case 30 has an integrally formed structure. Exemplarily, the case 30 can be integrally formed by a tensile process.

[0140] In some embodiments, the first inner wall surface 311 is a flat surface.

[0141] In some embodiments, the second inner wall surface 321 is a flat surface.

[0142] In some embodiments, the angle between the first inner wall surface 311 and the second inner wall surface 321 is 85° to 95°. Optionally, the first inner wall surface 311 is perpendicular to the second inner wall surface 321.

[0143] In some embodiments, the first inner wall surface 311 can be used to support the electrode assembly 10.

[0144] Exemplarily, the first inner wall surface 311 may directly support the electrode assembly 10, or may indirectly support the electrode assembly 10 by another member (for example, an insulating member 70).

[0145] When the battery cell 6 is in an operating state, the first inner wall surface 311 may be located below the electrode assembly 10 so as to support the electrode assembly 10.

[0146] The first inner wall surface 311 supports the electrode assembly 10, thereby reducing the risk of the corner of the electrode assembly 10 falling into the first retraction concave groove 35, increasing the pitch in the thickness direction Z of the first plate between the intersection of the first plate 31 and the second plate 32 and the electrode assembly 10, reducing the risk of the electrode assembly 10 being pressed by the intersection of the first plate 31 and the second plate 32, reducing the shedding of the active material of the electrode assembly 10, and enhancing the reliability of the battery cell 6.

[0147] In some embodiments, the electrode assembly 10 includes a first electrode plate 11 and a second electrode plate 12 with opposite polarities.

[0148] Exemplarily, one of the first electrode plate 11 and the second electrode plate 12 is a positive electrode plate, and the other is a negative electrode plate.

[0149] In some embodiments, the electrode assembly 10 may have a wound structure or a laminated structure.

[0150] In some embodiments, both the first electrode plate 11 and the second electrode plate 12 include straight layers 10a, and a plurality of straight layers 10a are provided in a laminated manner.

[0151] The straight layer 10a presents a straight state. Exemplarily, the straight layer 10a may be perpendicular to the lamination direction of the plurality of straight layers 10a.

[0152] The straight layer 10a of the first electrode plate 11 may be a portion in the straight state of the first electrode plate 11. The first electrode plate 11 may include one straight layer 10a or a plurality of straight layers 10a. For example, in a wound-type electrode assembly 10, one first electrode plate 11 can include a plurality of straight layers 10a, and in a laminated-type electrode assembly 10, one first electrode plate 11 can include only one straight layer 10a.

[0153] The straight layer 10a of the second electrode plate 12 may be a portion in a straight state of the second electrode plate 12. The second electrode plate 12 may include one straight layer 10a or a plurality of straight layers 10a. For example, in the wound electrode assembly 10, one second electrode plate 12 can include a plurality of straight layers 10a, and in the stacked electrode assembly 10, one second electrode plate 12 can include only one straight layer 10a.

[0154] In some embodiments, the stacking direction of the plurality of straight layers 10a of the electrode assembly 10 may be parallel to the thickness direction Z of the first plate or perpendicular to the thickness direction Z of the first plate.

[0155] In some embodiments, the straight layer 10a and the second plate 32 are provided to face each other. Exemplarily, the straight layer 10a and the second plate 32 are provided to face each other along the first direction Y.

[0156] In some embodiments, the plurality of straight layers 10a of the electrode assembly 10 are stacked along the first direction Y, and the first direction Y may be parallel to the thickness direction of the second plate 32.

[0157] In some embodiments, the second plate 32 is perpendicular to the first plate 31. Correspondingly, the first direction Y is perpendicular to the thickness direction Z of the first plate.

[0158] In some embodiments, the first inner wall surface 311 is perpendicular to the thickness direction Z of the first plate, and the second inner wall surface 321 is perpendicular to the thickness direction of the second plate 32.

[0159] In some embodiments, both ends of the first recessed groove 35 in the second direction X exceed the straight layer 10a. The thickness direction Z of the first plate, the first direction Y, and the second direction X are perpendicular to each other, and the first direction Y is parallel to the thickness direction of the second plate 32.

[0160] In the embodiment of the present application, both ends of the first recessed groove 35 in the second direction X exceed the straight layer 10a, so as to retract the straight layer 10a as much as possible, and increase the minimum distance between the intersection of the first plate 31 and the second plate 32 and the straight layer 10a closest to the second plate 32. When the battery cell 6 is subjected to an external impact, the risk that the straight layer 10a is pressed by the intersection of the first plate 31 and the second plate 32 can be reduced, the shedding of the active material of the straight layer 10a can be reduced, and the reliability of the battery cell 6 can be improved.

[0161] In some embodiments, the dimension of the first recessed groove 35 in the second direction X is larger than the dimension of the straight layer 10a in the second direction X.

[0162] In some embodiments, the housing 20 further includes a third plate 33, the third plate 33 is located on the side of the electrode assembly 10 in the second direction X, and is connected to the first plate 31 and the second plate 32. In the second direction X, the first recessed groove 35 and the third plate 33 are provided at intervals.

[0163] By separating the boundary of the three of the first plate 31, the second plate 32 and the third plate 33 and the first recessed groove 35 by a certain distance in the second direction X, the risk that the first recessed groove 35 extends to the boundary of the three plates is reduced, the stress concentration at the boundary of the three plates is alleviated, and the strength and reliability of the housing 20 are improved.

[0164] In some embodiments, the first plate 31, the second plate 32 and the third plate 33 are perpendicular to each other.

[0165] In some embodiments, the thickness direction of the third plate 33 is parallel to the second direction X.

[0166] In some embodiments, the first recessed groove 35 is a straight groove extending along the second direction X.

[0167] In some embodiments, the dimension of the first retraction groove 35 in the second direction X is smaller than the dimension of the first plate 31 in the second direction X.

[0168] In some embodiments, the first electrode plate 11 and the second electrode plate 12 are provided by being wound, the electrode assembly 10 includes a straight region 14 and a bending region 15, the bending region 15 is connected to an end of the straight region 14 in the second direction X, and a plurality of straight layers 10a are located in the straight region 14.

[0169] The straight region 14 is a region having a straight structure of the electrode assembly 10. In the straight region 14, both the first electrode plate 11 and the second electrode plate 12 are in a straight state. The straight layer 10a of the first electrode plate 11 is a layer located in the straight region 14 of the first electrode plate 11, and the straight layer 10a of the second electrode plate 12 is a layer located in the straight region 14 of the second electrode plate 12. Optionally, both the first electrode plate 11 and the second electrode plate 12 include a plurality of straight layers 10a.

[0170] The bending region 15 is a region having a bending structure in the electrode assembly 10. In the bending region 15, the first electrode plate 11, the second electrode plate 12, and the separator 13 are all bent. Exemplarily, the portion of the first electrode plate 11 located in the bending region 15 is bent in a substantially arc shape, and the portion of the second electrode plate 12 located in the bending region 15 is bent in a substantially arc shape.

[0171] In some embodiments, in the second direction X, the dimension of the straight region 14 is equal to the dimension of the straight layer 10a.

[0172] In some embodiments, the electrode assembly 10 includes two bending regions 15, and the two bending regions 15 are respectively connected to both ends of the straight region 14 in the second direction X.

[0173] In some embodiments, the dimension of the first recessed groove 35 in the second direction X is smaller than the dimension of the electrode assembly 10 in the second direction X.

[0174] In some embodiments, in the second direction X, the two bending regions 15 respectively extend beyond both ends of the first recessed groove 35.

[0175] In the first direction Y, there is a gap between the bending region 15 and the second plate 32. When the battery cell 6 is subjected to an external impact, the risk that the intersection of the first plate 31 and the second plate 32 and the bending region 15 are pressed against each other is small. In particular, the pitch between the end portion of the bending region 15 away from the straight region 14 in the second direction X and the second plate 32 is relatively large, and the end portion of the bending region 15 away from the straight region 14 in the second direction X is hardly affected by the second plate 32. Therefore, the first recessed groove 35 does not need to extend beyond the bending region 15 in the second direction X.

[0176] In some embodiments, the housing 20 further includes a third plate 33. The third plate 33 is located on the side of the electrode assembly 10 in the second direction X and is connected to the first plate 31 and the second plate 32.

[0177] The third plate 33 further includes a fourth inner wall surface 331 facing the electrode assembly 10. The housing 20 further includes a fifth inner wall surface 36 connecting the first inner wall surface 311 and the fourth inner wall surface 331. At least a part of the fifth inner wall surface 36 defines the second recessed groove 37. In the thickness direction Z of the first plate, the second recessed groove 37 is recessed away from the electrode assembly 10 with respect to the first inner wall surface 311. In the thickness direction Z of the first plate, at least a part of the projection of the bending region 15 on the first plate 31 overlaps with the second recessed groove 37.

[0178] Exemplarily, the planes where the first inner wall surface 311 is located, the planes where the second inner wall surface 321 is located, and the planes where the fourth inner wall surface 331 is located intersect in pairs.

[0179] The first reference plane S1 can be used to define the boundary of the second retraction groove 37. The opening of the second retraction groove 37 is located on the first reference plane S1.

[0180] In some examples, the second retraction groove 37 can be defined by a part of the fifth inner wall surface 36, that is, the groove wall surface of the second retraction groove 37 is a part of the fifth inner wall surface 36, and another part of the fifth inner wall surface 36 can be located outside the second retraction groove 37 (for example, on the side facing the electrode assembly 10 of the first reference plane S1). In an alternative embodiment, the second retraction groove 37 can be defined by the entire fifth inner wall surface 36, that is, the groove wall surface of the second retraction groove 37 is the fifth inner wall surface 36.

[0181] In the embodiment of the present application, the bending region 15 is retracted by the second retraction groove 37. When the battery cell 6 is subjected to an external impact, the risk that the bending region 15 is pressed by the intersection of the first plate 31 and the third plate 33 can be reduced, the shedding of the active material of the electrode assembly 10 can be reduced, the attenuation of the capacity of the battery cell 6 can be delayed, and the reliability of the battery cell 6 can be improved.

[0182] In some embodiments, in the first direction Y, the second retraction groove 37 and the second plate 32 are provided at intervals.

[0183] By separating the boundary portion of the three plates of the first plate 31, the second plate 32, and the third plate 33 and the second retraction groove 37 by a certain distance in the first direction Y, the risk that the second retraction groove 37 extends to the boundary portion of the three plates is reduced, the stress concentration at the boundary portion of the three plates is alleviated, and the strength and reliability of the housing 20 are improved.

[0184] In some embodiments, the second retraction groove 37 is a linear groove extending along the first direction Y.

[0185] In some embodiments, the dimension of the second retraction groove 37 in the first direction Y is smaller than the dimension of the first plate 31 in the first direction Y.

[0186] Since the surface facing the third plate 33 of the bending region 15 is bent substantially into a curved surface, there is a gap between the bending region 15 and the third plate 33. When the battery cell 6 is subjected to an external impact, there is a risk of pressing only the intersection of the first plate 31 and the third plate 33 at the end closest to the third plate 33 of the bending region 15. Since the dimension of the end closest to the third plate 33 of the bending region 15 in the first direction Y is smaller than the dimension of the straight region 14 in the first direction Y, the second retreat groove 37 can have a dimension smaller than that of the first plate 31 in the first direction Y.

[0187] In some embodiments, there are a plurality of electrode assemblies 10, and the plurality of electrode assemblies 10 are provided stacked along the first direction Y. Optionally, the number of electrode assemblies 10 is two or four.

[0188] In some embodiments, in the thickness direction Z of the first plate, the projection of the bending region 15 of each electrode assembly 10 onto the first plate 31 all has a portion overlapping with the second retreat groove 37.

[0189] The bending regions 15 of a plurality of electrode assemblies 10 can be simultaneously retracted by one second retreat groove 37. When the battery cell 6 is subjected to an external impact, the shedding of the active material of the electrode assembly 10 can be reduced, and the reliability of the battery cell 6 can be improved.

[0190] In some embodiments, the case 30 is a rectangular case.

[0191] In some embodiments, the housing 20 includes two second plates 32 provided opposite to each other along the first direction Y and two third plates 33 provided opposite to each other along the second direction X. The second inner wall surface 321 of each second plate 32 is connected to the first inner wall surface 321 by at least one third inner wall surface 34, and the fourth inner wall surface 331 of each third plate 33 is connected to the first inner wall surface 311 by at least one fifth inner wall surface 36.

[0192] One first retraction groove 35 is defined by each third inner wall surface 34, and one second retraction groove 37 is defined by each fifth inner wall surface 36.

[0193] Exemplarily, one third inner wall surface 34 connects one end of the first inner wall surface 321 in the first direction Y and the second inner wall surface 321 of one second plate 32, and the other third inner wall surface 34 connects the other end of the first inner wall surface 321 in the first direction Y and the second inner wall surface 321 of the other second plate 32.

[0194] Exemplarily, one fifth inner wall surface 36 connects one end of the first inner wall surface 321 in the second direction X and the fourth inner wall surface 331 of one third plate 33, and the other fifth inner wall surface 36 connects the other end of the first inner wall surface 321 in the second direction X and the fourth inner wall surface 331 of the other third plate 33.

[0195] Exemplarily, in the thickness direction Z of the first plate, there may be a portion that overlaps with the projection of the electrode assembly 10 onto the first plate 31 only in one first retraction groove 35, or there may be a portion that overlaps with the projection of the electrode assembly 10 onto the first plate 31 in any of the two first retraction grooves 35.

[0196] Exemplarily, in the thickness direction Z of the first plate, there may be a portion that overlaps with the projection of the electrode assembly 10 onto the first plate 31 only in one second retraction groove 37, or there may be a portion that overlaps with the projection of the electrode assembly 10 onto the first plate 31 in any of the two second retraction grooves 37.

[0197] In the embodiment of the present application, by providing the first retraction groove 35 and the second retraction groove 37 around the periphery of the first plate 31, even when the position of the electrode assembly 10 is displaced, the electrode assembly 10 can still be effectively retracted, and the risk of the corner portion of the electrode assembly 10 being pressed can be reduced.

[0198] In some embodiments, the case 30 includes a first plate 31, two second plates 32, and two third plates 33. Exemplarily, the first plate 31 may be the bottom plate of the case 30, the two second plates 32 are two opposing side plates of the case 30 in the first direction Y, and the two third plates 33 are two opposing side plates of the case 30 in the second direction X.

[0199] In some embodiments, there are two first recessed grooves 35 and two second recessed grooves 37, and the two first recessed grooves 35 and the two second recessed grooves 37 are alternately provided along the circumferential direction of the case 30.

[0200] In some embodiments, the third inner wall surface 34 includes a first surface 341 and a second surface 342. The first surface 341 is a curved surface and is connected to the second inner wall surface 321. The second surface 342 connects the first surface 341 and the first inner wall surface 311. At least a part of the first surface 341 and the second surface 342 define the first recessed groove 35.

[0201] The second surface 342 can include at least one of a flat surface and a curved surface. In some examples, the second surface 342 may be a single flat surface. In another example, the second surface 342 may include a plurality of flat surfaces provided intersectingly. In another example, the second surface 342 may include a flat surface and a curved surface.

[0202] The groove wall surface of the first recessed groove 35 may include only a part of the first surface 341 or may include the entire first surface 341.

[0203] The first surface 341 may be directly connected to the second inner wall surface 321 or may be indirectly connected to the second inner wall surface 321 by other parts of the third inner wall surface 34.

[0204] By providing the first arcuate surface 341, a substantially fillet structure is formed at the intersection of the first plate 31 and the second plate 32, thereby dispersing stress during the forming process, reducing stress concentration, and enhancing the reliability of the housing 20. At least a part of the first surface 341 is hidden in the first recessed groove 35. In this way, when the battery cell 6 is subjected to an external impact, the risk that the electrode assembly 10 is pressed by the first surface 341 is reduced, the shedding of the active material of the electrode assembly 10 is decreased, the attenuation of the capacity of the battery cell 6 is delayed, and the reliability of the battery cell 6 can be enhanced.

[0205] In some embodiments, the first surface 341 includes a first region 3411 and a second region 3412. The first region 3411 protrudes from the side facing the electrode assembly 10 of the first inner wall surface 311 in the thickness direction Z of the first plate and is connected to the second inner wall surface 321. The second region 3412 connects the first region 3411 and the second surface 342, and the first recessed groove 35 is defined by the second region 3412 and the second surface 342.

[0206] Exemplarily, the intersection line of the first reference plane S1 and the first surface 341 is the boundary line between the first region 3411 and the second region 3412.

[0207] The isolation member 13 of the electrode assembly 10 can play a role of support and buffering to a certain extent. Even if the first surface 341 has the first region 3411 protruding from the first inner wall surface 311, the isolation member 13 can isolate the first region 3411 from the electrode plate of the electrode assembly 10 to a certain extent, reduce the shedding of the active material of the electrode assembly 10, and enhance the reliability of the battery cell 6. In the embodiments of the present application, only a part of the first surface 341 (i.e., the second region 3412) is hidden in the first recessed groove 35, the requirement for the depth of the first recessed groove 35 can be reduced, and the forming difficulty can be decreased.

[0208] In some embodiments, the first surface 341 is an arc surface, and both ends of the first surface 341 are in contact with the second inner wall surface 321 and the second surface 342 respectively.

[0209] In some embodiments, the radius of the first surface 341 is R, and in the thickness direction Z of the first plate, the dimension of the region located in the first recessed groove 35 of the first surface 341 is d. 0.1R ≤ d ≤ R.

[0210] For example, the region located in the first recessed groove 35 of the first surface 341 may be the second region 3412.

[0211] In the embodiments of the present application, by limiting d to be not less than 0.1R, the arc surface hidden in the first recessed groove 35 has a large arc length, so that the electrode assembly 10 can be effectively retracted, the risk that the electrode assembly 10 is pressed by the first surface 341 is reduced, the shedding of the active material of the electrode assembly 10 is reduced, the attenuation of the capacity of the battery cell 6 is delayed, and the reliability of the battery cell 6 is improved.

[0212] In the embodiments of the present application, by limiting d to be not more than R, the maximum depth of the first recessed groove 35 is limited, the loss of the strength of the housing 20 is reduced, and the reliability of the battery cell 6 is improved.

[0213] Exemplarily, d is 0.1R, 0.2R, 0.3R, 0.4R, 0.5R, 0.6R, 0.7R, 0.8R, 0.9R or R.

[0214] In some embodiments, 0.3R ≤ d ≤ 0.9R so as to further improve the reliability of the battery cell 6.

[0215] In some embodiments, in the thickness direction Z of the first plate, the maximum depth of the first recessed groove 35 is equal to d.

[0216] In some embodiments, the second surface 342 is perpendicular to the second inner wall surface 321. Correspondingly, the central angle of the first surface 341 may be 90°.

[0217] In some embodiments, the second surface 342 includes a third region 3421 and a fourth region 3422 that are provided intersectingly. The third region 3421 is connected to the first surface 341 and is parallel to the first inner wall surface 311. The fourth region 3422 connects the third region 3421 and the first inner wall surface 311.

[0218] The fourth region 3422 may be a plane or a curved surface.

[0219] By providing the third region 3421 parallel to the first inner wall surface 311, the uniformity of the force received during the pressing and forming process of the first retraction groove 35 can be enhanced.

[0220] In some embodiments, in the thickness direction of the second plate 32, the maximum dimension w of the first retraction groove 35 is 1 mm to 10 mm.

[0221] Exemplarily, w may be the maximum width of the first retraction groove 35. Optionally, w is 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm.

[0222] In the embodiments of the present application, by limiting w to 1 mm or more, the retraction space is enlarged, the risk that the electrode assembly 10 is pressed by the intersection of the first plate 31 and the second plate 32 is reduced, and the reliability is enhanced. In the embodiments of the present application, by limiting w to 10 mm or less, during the pressing and forming process of the first retraction groove 35, the flow of the material is reduced, the forming difficulty of the first retraction groove 35 is decreased, and the flatness of the first plate 31 is enhanced.

[0223] In some embodiments, so as to further reduce the forming difficulty and enhance the reliability, w is 3 mm to 8 mm.

[0224] In some embodiments, in the thickness direction Z of the first plate, the maximum hardness of the portion of the housing 20 corresponding to the first retraction groove 35 is greater than the maximum hardness of the portion of the first inner wall surface 311 of the first plate 31.

[0225] The portion of the housing 20 corresponding to the first retraction concave groove 35 in the thickness direction Z of the first plate can be abbreviated as the concave groove portion. Since the minimum thickness of the concave groove portion may be reduced by the formation of the first retraction concave groove 35, by increasing the maximum hardness of the concave groove portion, the damage to the structural strength caused by the formation of the first retraction concave groove 35 can be reduced, the risk of the concave groove portion cracking can be lowered, and the reliability of the battery cell 6 can be enhanced.

[0226] In some embodiments, the third inner wall surface 34 is on the side closer to the first inner wall surface 311 of the plane where the second inner wall surface 321 is located.

[0227] Exemplarily, the plane where the second inner wall surface 321 is located may be the second reference plane S2. Optionally, the first reference plane S1 is perpendicular to the second reference plane S2.

[0228] The third inner wall surface 34 can be formed by the pressing of an external die head. After the third inner wall surface 34 is formed, the external die head can be withdrawn along the thickness direction Z of the first plate. In the embodiments of the present application, the third inner wall surface 34 is provided on the side closer to the first inner wall surface 311 of the plane where the second inner wall surface 321 is located, which can reduce the interference of the second inner wall surface 321 with respect to the external die head and facilitate the withdrawal of the die head.

[0229] FIG. 9 is a partial cross-sectional view in the A-A direction of FIG. 8, and FIG. 10 is a partial cross-sectional view in the A-A direction of FIG. 8. Here, for the sake of easy understanding, it is explained that in FIGS. 9 and 10, simplification processing is performed, and some structures are omitted. For example, only a partial cross-section of the second plate is shown in FIG. 9, and only a partial cross-section of the third plate is shown in FIG. 10.

[0230] Referring to FIGS. 8 to 10, in some embodiments, the housing 20 further includes a first arc surface 381. The first arc surface 381 is located on the side in the second direction X of the first retraction concave groove 35, and the first arc surface 381 connects the first inner wall surface 311 and the second inner wall surface 321.

[0231] In some embodiments, the radius of the first arc surface 381 is the same as the radius of the first surface 341.

[0232] In some embodiments, the center of the first surface 341 is arranged along the thickness direction Z of the first plate relative to the center of the first arc surface 381. Exemplarily, the center of the first surface 341 is lower than the center of the first arc surface 381 by a certain distance (e.g., d).

[0233] In some embodiments, in the thickness direction Z of the first plate, the first arc surface 381 does not overlap with the electrode assembly 10.

[0234] In some embodiments, the housing 20 further includes a second arc surface 382, which is located on the side of the second retraction groove 37 in the first direction Y, and the second arc surface 382 connects the first inner wall surface 311 and the fourth inner wall surface 331.

[0235] In some embodiments, the fifth inner wall surface 36 includes a third surface 361 and a fourth surface 362. The third surface 361 is a curved surface and is connected to the fourth inner wall surface 331, and the fourth surface 362 connects the third surface 361 and the first inner wall surface 311. At least a part of the third surface 361 and the fourth surface 362 define the second retraction groove 37.

[0236] In some embodiments, the third surface 361 is an arc surface.

[0237] In some embodiments, the radius of the second arc surface 382 is the same as the radius of the third surface 361.

[0238] In some embodiments, the center of the third surface 361 is arranged along the thickness direction Z of the first plate relative to the center of the second arc surface 382. Exemplarily, the center of the third surface 361 is lower than the center of the second arc surface 382 by a certain distance (e.g., d).

[0239] In some embodiments, in the thickness direction Z of the first plate, the second arc surface 382 does not overlap with the electrode assembly 10.

[0240] FIG. 11 is a schematic top view of the case of a battery cell provided by some other embodiments of the present application. The dotted line is the contour of the projection of the electrode assembly onto the case.

[0241] As shown in FIG. 11, in some embodiments, there are a plurality of electrode assemblies 10, and the plurality of electrode assemblies 10 are stacked and provided along the first direction Y. A plurality of fifth inner wall surfaces 36 provided at intervals along the first direction Y connect the first inner wall surface 311 and the fourth inner wall surface 331, and a plurality of second retraction grooves 37 are defined by the plurality of fifth inner wall surfaces 36.

[0242] In the thickness direction Z of the first plate, each second retraction groove 37 has a portion that overlaps with the projection of the bending region 15 of at least one electrode assembly 10 onto the first plate.

[0243] One second retraction groove 37 is defined by one fifth inner wall surface 36.

[0244] One second retraction groove 37 may be used to retract only the bending region 15 of one electrode assembly 10, or may be used to retract the bending regions 15 of two or more electrode assemblies 10 at the same time.

[0245] Since the bending regions 15 of the plurality of electrode assemblies 10 are provided at intervals along the first direction Y, a plurality of second retraction grooves 37 with intervals can be provided to retract the bending regions 15 of the plurality of electrode assemblies 10. In this way, the extension length of a single second retraction groove 37 can be shortened, and the forming difficulty of the second retraction groove 37 can be reduced.

[0246] In some embodiments, the number of the fifth inner wall surfaces 36 connected to one end of the first inner wall surface 311 in the second direction X is equal to the number of the electrode assemblies 10.

[0247] In some embodiments, each second retraction groove 37 has a portion that overlaps only the projection of one bending region 15 of one electrode assembly 10 onto the first plate 31.

[0248] FIG. 12 is a schematic cross-sectional view of a battery cell provided by some other embodiments of the present application, FIG. 13 is a schematic structural view of a case of a battery cell provided by some embodiments of the present application, and FIG. 14 is an enlarged schematic view of the circular frame portion of FIG. 12.

[0249] Referring to FIGS. 12 to 14, in some embodiments, the electrode assembly 10 has a laminated structure.

[0250] In some embodiments, the electrode assembly 10 includes a plurality of first electrode plates 11, and the plurality of first electrode plates 11 are laminated and provided along the first direction Y, and each first electrode plate 11 includes one straight layer 10a.

[0251] In some embodiments, the electrode assembly 10 includes a plurality of second electrode plates 12, and the plurality of first electrode plates 11 and the plurality of second electrode plates 12 are alternately laminated along the first direction Y. Each second electrode plate 12 includes one straight layer 10a.

[0252] In another embodiment, the electrode assembly 10 includes at least one second electrode plate 12, and the second electrode plate 12 is continuously folded to form a plurality of straight layers 10a that are laminated and provided. The plurality of straight layers 10a of the second electrode plate 12 and the plurality of first electrode plates 11 are alternately laminated along the first direction Y.

[0253] In some embodiments, the housing 20 includes two first plates 31 provided opposite to each other along the thickness direction Z of the first plate and two second plates 32 provided opposite to each other along the first direction Y. Exemplarily, the first plate 31 and the second plate 32 are alternately provided along the circumferential direction of the housing 20.

[0254] In some embodiments, both ends of the first inner wall surface 311 of each first plate 31 in the first direction Y are respectively connected to the second inner wall surfaces 321 of the two second plates 32 by two third inner wall surfaces 34.

[0255] One end of the first inner wall surface 311 of the first plate 31 in the first direction Y is connected to the second inner wall surface 321 of one second plate 32 by one third inner wall surface 34, and the other end of the first inner wall surface 311 of the first plate 31 in the first direction Y is connected to the second inner wall surface 321 of the other second plate 32 by the other third inner wall surface 34.

[0256] Exemplarily, four third inner wall surfaces 34 are provided on the housing 20, and the four third inner wall surfaces 34 may be provided at four corners of the housing 20. Correspondingly, four first recessed grooves 35 are defined by the four third inner wall surfaces 34.

[0257] The first recessed groove 35 retracts the first electrode plate 11 closest to one second plate 32 and the first electrode plate 11 closest to the other second plate 32. When the battery cell 6 is subjected to an impact in the thickness direction Z of the first plate, the risk that the first electrode plate 11 is pressed by the intersection of the first plate 31 and the second plate 32 can be reduced, the shedding of the active material can be reduced, the attenuation of the capacity of the battery cell 6 can be delayed, and the reliability of the battery cell 6 can be improved.

[0258] In some embodiments, the case 30 includes two first plates 31 and two second plates 32. Both ends of the case 30 in the second direction X are open, the housing 20 includes two end caps 40, and the two end caps 40 respectively cover the two openings of the case 30.

[0259] In some embodiments, the first recessed groove 35 penetrates the case 30 along the second direction X. Exemplarily, the dimension of the first recessed groove 35 in the second direction X is equal to the dimension of the first plate 31 in the second direction X.

[0260] In some embodiments, a third retraction groove 39 communicating with the first retraction groove 35 is further defined by the third inner wall surface 34. In the thickness direction of the second plate, the third retraction groove 39 is recessed away from the electrode assembly 10 with respect to the second inner wall surface 321. In the thickness direction of the second plate, a part of the projection of the electrode assembly 10 onto the second plate 32 overlaps with the third retraction groove 39. Exemplarily, the thickness direction of the second plate is parallel to the first direction Y.

[0261] The first retraction groove 35 and the third retraction groove 39 are simultaneously defined by the third inner wall surface 34.

[0262] The second reference plane S2 can be used to define the boundary of the third retraction groove 39. The opening of the third retraction groove 39 is located in the second reference plane S2.

[0263] The first retraction groove 35 and the third retraction groove 39 may communicate directly or indirectly through other spaces.

[0264] In the embodiments of the present application, when the battery cell 6 is subjected to an impact in the thickness direction of the second plate, the third retraction groove 39 can reduce the risk that the first electrode plate 11 is pressed by the intersection of the first plate 31 and the second plate 32, reduce the shedding of the active material, delay the attenuation of the capacity of the battery cell 6, and improve the reliability of the battery cell 6.

[0265] In some embodiments, in the thickness direction Z of the first plate, the third retraction groove 39 is on the side facing the electrode assembly 10 of the plane where the first inner wall surface 311 is located.

[0266] Exemplarily, in the thickness direction Z of the first plate, the third retraction groove 39 may be at a certain distance from the first reference plane S1 or may extend to the first reference plane S1.

[0267] In some embodiments, the third inner wall surface 34 further includes a fifth surface 343, and the third retraction groove 39 is defined by at least a part of the fifth surface 343 and the first region 3411.

[0268] In some embodiments, the first region 3411 includes a first sub-region 3411a and a second sub-region 3411b. The third recessed groove 39 is defined by the first sub-region 3411a and the fifth surface 343. The second sub-region 3411b connects the first sub-region 3411a and the second region 3412. Exemplarily, the intersection line of the first reference plane S1 and the first surface 341 is the boundary line between the second sub-region 3411b and the second region 3412, and the intersection line of the second reference plane S2 and the first surface 341 is the boundary line between the first sub-region 3411a and the second sub-region 3411b. Alternatively, in some embodiments, the third recessed groove 39 is defined by the entire fifth surface 343 and the first region 3411. In other words, the second sub-region 3411b may be omitted.

[0269] In some embodiments, the fifth surface 343 includes a fifth region 3431 and a sixth region 3432. The fifth region 3431 is parallel to the second inner wall surface 321 and connected to the first surface 341. The sixth region 3432 connects the fifth region 3431 and the second inner wall surface 321.

[0270] FIG. 15 is a schematic top view of the case of a battery cell provided by some other embodiments of the present application, and FIG. 16 is an enlarged schematic view of the circular frame portion of FIG. 15.

[0271] As shown in FIGS. 15 and 16, in some embodiments, both ends of the first recessed groove 35 communicate with two second recessed grooves 37 respectively.

[0272] Exemplarily, an annular recessed groove is provided around the first inner wall surface 311 of the housing 20, and the annular recessed groove includes two first recessed grooves 35.

[0273] In the embodiments of the present application, by communicating the first recessed groove 35 and the second recessed groove 37, the structure of the mold can be simplified and the molding efficiency can be improved.

[0274] FIG. 17 is a schematic partial cross-sectional view of a battery cell case provided by some other embodiments of the present application.

[0275] As shown in FIG. 17, in some embodiments, the third inner wall surface 34 includes a first surface 341 and a second surface 342. The first surface 341 is a curved surface and is connected to the second inner wall surface 321. The second surface 342 connects the first surface 341 and the first inner wall surface 311. At least a part of the first surface 341 and the second surface 342 define the first recessed groove 35.

[0276] The second surface 342 may be an inclined surface that is inclined with respect to the first inner wall surface 311.

[0277] FIG. 18 is a schematic partial cross-sectional view of a battery cell case provided by some other embodiments of the present application.

[0278] In some embodiments, the third inner wall surface 34 includes an arc surface, and the central angle of the arc surface is greater than 90°. The first recessed groove 35 can be directly defined by the arc surface.

[0279] FIG. 19 is a schematic partial cross-sectional view of a battery cell case provided by some other embodiments of the present application.

[0280] As shown in FIG. 19, in some embodiments, the third inner wall surface 34 includes a first surface 341 and a second surface 342. The first surface 341 is a curved surface and is connected to the second inner wall surface 321. The second surface 342 connects the first surface 341 and the first inner wall surface 311. The first recessed groove 35 is defined by the first surface 341 and the second surface 342.

[0281] In some embodiments, the first surface 341 is a flat surface, and the first surface 341 and the second inner wall surface 321 are flush.

[0282] The intersection line of the first reference plane S1 and the second reference plane S2 can be the boundary line between the first surface 341 and the second inner wall surface 321.

[0283] FIG. 20 is a schematic partial cross-sectional view of a case of a battery cell provided by some other embodiments of the present application.

[0284] As shown in FIG. 20, in some embodiments, the third inner wall surface 34 includes a first surface 341 and a second surface 342. The first surface 341 is a curved surface and is connected to the second inner wall surface 321. The second surface 342 connects the first surface 341 and the first inner wall surface 311. A first recessed groove 35 is defined by the first surface 341 and the second surface 342. The first surface 341 is a curved surface. The second surface 342 can be entirely hidden in the first recessed groove 35.

[0285] The intersection line of the first reference plane S1 and the second reference plane S2 can be the boundary line between the first surface 341 and the second inner wall surface 321.

[0286] According to some embodiments of the present application, the present application further provides a battery including a plurality of battery cells according to any one of the above embodiments.

[0287] According to some embodiments of the present application, the present application further provides an electrical device including a battery according to any one of the above embodiments for providing electrical energy. The electrical device may be a device or system applying any one of the above-described battery cells.

[0288] Referring to FIGS. 4 to 8, an embodiment of the present application provides a battery cell 6 including a housing 20 and an electrode assembly 10 housed in the housing 20.

[0289] The housing 20 includes a case 30 and an end cap 40. The case 30 has an opening, and the end cap 40 covers the opening of the case 30. The case 30 includes a first plate 31, two second plates 32 provided opposite to each other along a first direction Y, and two third plates 33 provided opposite to each other along a second direction X. The first plate 31 faces the opening of the case 30. The two second plates 32 are respectively connected to both ends of the first plate 31 in the second direction X. The two third plates 33 are respectively connected to both ends of the first plate 31 in the first direction Y. The first direction Y, the second direction X, and the thickness direction Z of the first plate are perpendicular to each other in pairs. Both ends of each second plate 32 are respectively connected to the two third plates 33. Exemplarily, the first plate 31, the second plates 32, and the third plates 33 are perpendicular to each other.

[0290] The electrode assembly 10 has a winding structure and includes a straight region 14 and two bending regions 15. The two bending regions 15 are respectively connected to both ends of the straight region 14 in the second direction X.

[0291] The first plate 31 includes a first inner wall surface 311 facing the electrode assembly 10, and the second plate 32 includes a second inner wall surface 321 facing the electrode assembly 10. The housing 20 includes a third inner wall surface 34 connecting the first inner wall surface 311 and the second inner wall surface 321. At least a part of the third inner wall surface 34 defines a first retraction concave groove 35. In the thickness direction Z of the first plate, the first retraction concave groove 35 is recessed away from the electrode assembly 10 with respect to the first inner wall surface 311, and a part of the projection of the straight region 14 onto the first plate 31 overlaps with the first retraction concave groove 35.

[0292] Along the second direction X, both ends of the first retraction concave groove 35 extend beyond the straight region 14, and both ends of the first retraction concave groove 35 are respectively spaced apart from the corresponding third plates 33 by a certain distance.

[0293] The third plate 33 further includes a fourth inner wall surface 331 facing the electrode assembly 10, and the housing 20 further includes a fifth inner wall surface 36 connecting the first inner wall surface 311 and the fourth inner wall surface 331. At least a part of the fifth inner wall surface 36 defines a second retraction groove 37. In the thickness direction Z of the first plate, the second retraction groove 37 is recessed toward the side away from the electrode assembly 10 with respect to the first inner wall surface 311. In the thickness direction Z of the first plate, at least a part of the projection of the bending region 15 onto the first plate 31 overlaps with the second retraction groove 37. Along the first direction Y, both ends of the second retraction groove 37 are spaced apart from the corresponding second plate 32 by a certain distance.

[0294] In the circumferential direction of the case 30, the two first retraction grooves 35 and the two second retraction grooves 37 are provided alternately, and the first retraction groove 35 and the second retraction groove 37 are separated from each other.

[0295] Unless there is a contradiction, it should be noted that the embodiments and features in the embodiments according to the present application can be combined with each other.

[0296] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the above embodiments, as can be understood by those skilled in the art, the technical solutions described in the above embodiments can still be modified, or equivalent substitutions can be made for some of their technical features. By these modifications and substitutions, the essence of the corresponding technical solutions does not deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Description of Reference Numerals

[0297] 1 Vehicle 2 Battery 3 Controller 4 Motor 5 Housing 5a First housing part 5b Second housing part 5c Storage space 6 Battery cell 10 Electrode assembly 11 First electrode plate 12 Second electrode plate 13 Separation member 14 Straight region 15 Bending region 10a Straight layer 20 Housing 30 Case 40 End cap 50 Electrode terminal 60 Adapter 70 Insulating member 31 First plate 311 First inner wall surface 32 Second plate 321 Second inner wall surface 33 Third plate 331 Fourth inner wall surface 34 Third inner wall surface 341 First surface 3411 First region 3411a First sub-region 3411b Second sub-region 3412 Second region 342 Second surface 3421 Third region 3422 Fourth region 343 Fifth surface 3431 Fifth region 3432 Sixth region 35 First recessed groove for retreat 36 Fifth inner wall surface 361 Third surface 362 Fourth surface 37 Second recessed groove for retreat 381 First arc surface 382 Second arc surface 39 Third recessed groove for retreat S1 First reference plane S2 Second reference plane Z Thickness direction of the first plate Y First direction X Second direction

Claims

1. A battery cell including a housing and an electrode assembly housed in the housing, wherein the housing includes a first plate and a second plate, the second plate and the first plate are provided intersecting each other, the first plate includes a first inner wall surface facing the electrode assembly, and the second plate includes a second inner wall surface facing the electrode assembly, the housing includes a third inner wall surface connecting the first inner wall surface and the second inner wall surface, at least a part of the third inner wall surface defines a first recessed groove, and in the thickness direction of the first plate, the first recessed groove is recessed toward the side away from the electrode assembly with respect to the first inner wall surface, and a part of the projection of the electrode assembly onto the first plate overlaps with the first recessed groove. A battery cell.

2. The battery cell according to claim 1, wherein the first inner wall surface is used to support the electrode assembly.

3. The electrode assembly includes a first electrode plate and a second electrode plate with opposite polarities. The first electrode plate and the second electrode plate both include a straight layer provided opposite to the second plate. The plurality of straight layers are stacked along a first direction. Both ends of the first recessed groove in a second direction exceed the straight layer, wherein the thickness direction of the first plate, the first direction, and the second direction are perpendicular to each other, and the first direction is parallel to the thickness direction of the second plate. The battery cell according to claim 1 or 2.

4. The housing further includes a third plate, the third plate is located on the side of the electrode assembly in the second direction, and is connected to the first plate and the second plate, The battery cell according to claim 3, wherein in the second direction, the first recessed groove and the third plate are provided at an interval.

5. The first electrode plate and the second electrode plate are provided in a wound manner. The electrode assembly includes a straight region and a bent region. The bent region is connected to an end of the straight region in the second direction. The plurality of straight layers are located in the straight region. The battery cell according to claim 3 or 4.

6. The housing further includes a third plate, the third plate is located on the side of the electrode assembly in the second direction, and is connected to the first plate and the second plate, The third plate further includes a fourth inner wall surface facing the electrode assembly, the housing further includes a fifth inner wall surface connecting the first inner wall surface and the fourth inner wall surface, at least a part of the fifth inner wall surface defines a second retraction groove, and in the thickness direction of the first plate, the second retraction groove is recessed away from the electrode assembly with respect to the first inner wall surface. The battery cell according to claim 5, wherein, in the thickness direction of the first plate, at least a part of the projection of the bent region onto the first plate overlaps with the second retraction groove.

7. The housing includes two of the second plates provided to face each other along the first direction and two of the third plates provided to face each other along the second direction, the second inner wall surface of each of the second plates is connected to the first inner wall surface by at least one of the third inner wall surfaces, and the fourth inner wall surface of each of the third plates is connected to the first inner wall surface by at least one of the fifth inner wall surfaces. The battery cell according to claim 6.

8. The battery cell according to claim 6 or 7, wherein in the first direction, the second retraction groove and the second plate are provided at intervals.

9. Both ends of the first retraction groove communicate with two of the second retraction grooves respectively. The battery cell according to claim 6 or 7.

10. There are a plurality of the electrode assemblies, the plurality of the electrode assemblies are stacked and provided along the first direction, and in the thickness direction of the first plate, the projection of the bent region of each of the electrode assemblies onto the first plate all has a portion overlapping with the second retraction groove. The battery cell according to any one of claims 6 to 9.

11. There are a plurality of the electrode assemblies, the plurality of the electrode assemblies are stacked and provided along the first direction. A plurality of the fifth inner wall surfaces provided at intervals along the first direction connect the first inner wall surface and the fourth inner wall surface, a plurality of the second retraction grooves are defined by the plurality of the fifth inner wall surfaces, and in the thickness direction of the first plate, each of the second retraction grooves has a portion overlapping with the projection of the bent region of at least one of the electrode assemblies onto the first plate. The battery cell according to any one of claims 6 to 8.

12. The electrode assembly includes a plurality of the first electrode plates, and the plurality of the first electrode plates are stacked and provided along the first direction. Each of the first electrode plates includes one of the straight layers. The housing includes two of the first plates provided to face each other along the thickness direction of the first plate and two of the second plates provided to face each other along the first direction. The first plate and the second plate are alternately provided in the circumferential direction of the housing. The battery cell according to claim 3 or 4, wherein both ends of the first inner wall surface of each of the first plates in the first direction are respectively connected to the second inner wall surfaces of the two second plates by the two third inner wall surfaces.

13. A third recessed groove communicating with the first recessed groove is further defined by the third inner wall surface. In the thickness direction of the second plate, the third recessed groove is recessed toward the side away from the electrode assembly with respect to the second inner wall surface. In the thickness direction of the second plate, a part of the projection of the electrode assembly onto the second plate overlaps with the third recessed groove. The battery cell according to any one of claims 1 to 12.

14. The third inner wall surface includes a first surface and a second surface. The first surface is a curved surface and is connected to the second inner wall surface. The second surface connects the first surface and the first inner wall surface. The battery cell according to any one of claims 1 to 13, wherein the first recessed groove is defined by at least a part of the first surface and the second surface.

15. The first surface includes a first region and a second region. The first region protrudes from the side facing the electrode assembly of the first inner wall surface in the thickness direction of the first plate and is connected to the second inner wall surface. The second region connects the first region and the second surface. The battery cell according to claim 14, wherein the first recessed groove is defined by the second region and the second surface.

16. The first surface is an arc surface. Both ends of the first surface are in contact with the second inner wall surface and the second surface respectively. The radius of the first surface is R. In the thickness direction of the first plate, the dimension of the region of the first surface located in the first recessed groove is d, and 0.1R ≤ d ≤ R. Optionally, 0.3R ≤ d ≤ 0.9R. The battery cell according to claim 14 or 15.

17. The second surface includes a third region and a fourth region provided intersectingly, the third region being connected to the first surface and parallel to the first inner wall surface, and the fourth region connecting the third region and the first inner wall surface. The battery cell according to any one of claims 14 to 16.

18. In the thickness direction of the second plate, the maximum dimension w of the first retracted concave groove is 1 mm to 10 mm, and optionally, w is 3 mm to 8 mm. The battery cell according to any one of claims 1 to 17.

19. The maximum hardness of the portion of the housing corresponding to the first retracted concave groove in the thickness direction of the first plate is greater than the maximum hardness of the portion of the first plate corresponding to the first inner wall surface. The battery cell according to any one of claims 1 to 18.

20. The third inner wall surface is on the side closer to the first inner wall surface of the plane where the second inner wall surface is located. The battery cell according to claim 1.

21. The housing includes a case and an end cap, the case has an opening, the end cap covers the opening, and the case includes the first plate and the second plate. The battery cell according to any one of claims 1 to 20.

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

23. An electrical device including the battery according to claim 22 for providing electrical energy.

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