Battery monomer, battery and electric device

Abstract

The invention relates to a battery monomer, a battery and a power utilization device, the battery monomer comprises a shell and a first protection layer, the shell is provided with a wall part, the wall part is provided with a weak part, and the weak part is configured to be broken when the internal pressure or temperature of the battery monomer reaches a threshold value; the first protective layer is disposed on the wall portion and covers at least part of the weak portion. The battery monomer provided by the invention comprises the shell and the first protection layer, the shell is provided with the wall part, the wall part is provided with the weak part, the weak part is broken when the internal pressure or temperature of the battery monomer reaches a threshold value, and the first protection layer covers at least part of the weak part, so that protection is formed by the weak part, corrosion of the weak part is reduced, and the service life of the battery monomer is prolonged. The influence on the bursting pressure of the weak part is improved.

Description

Battery cells, batteries and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202322829230.6, filed on October 20, 2023, entitled “Battery Cell, Battery and Electrical Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery production technology, and in particular to battery cells, batteries, and electrical devices. Background Art

[0004] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and power tools. Battery cells can include nickel-cadmium battery cells, nickel-metal hydride battery cells, lithium-ion battery cells, and secondary alkaline zinc-manganese battery cells.

[0005] In the development of battery technology, how to improve battery reliability is a technical problem that needs to be solved urgently.

[0006] Summary of the Invention

[0007] The present application provides a battery cell, a battery, and an electrical device, aiming to improve the reliability of the battery to a certain extent.

[0008] In a first aspect, the present application proposes a battery cell, which includes an outer shell and a first protective layer. The outer shell has a wall portion, and the wall portion is provided with a weak portion. The weak portion is configured to rupture when the internal pressure or temperature of the battery cell reaches a threshold value; the first protective layer is arranged on the wall portion and covers at least part of the weak portion.

[0009] The battery cell provided in this application includes a housing and a first protective layer. The housing has a wall portion, and the wall portion is provided with a weak portion. The weak portion ruptures when the internal pressure or temperature of the battery cell reaches a threshold value. The first protective layer covers at least a portion of the weak portion, protecting the weak portion, reducing corrosion of the weak portion, and improving the impact of the burst pressure of the weak portion. In addition, the first protective layer provides a certain degree of buffering for the weak portion, thereby reducing the risk of the weak portion rupturing and scratching or injuring people or objects when the internal pressure of the battery cell reaches a threshold value. It can also effectively alleviate the possibility of premature rupture of the weak portion during use. Therefore, it is beneficial to improve the service life and reliability of the battery cell with the first protective layer.

[0010] According to one embodiment of the present application, the first protective layer is located on the outer side of the wall.

[0011] In these optional embodiments, the first protective layer is located outside the wall portion, which not only achieves corrosion protection but also does not occupy space within the battery cell, thereby increasing the energy density of the battery cell. In addition, when the battery cell is subjected to an impact force, the first protective layer outside the battery cell can disperse the force, thereby reducing the impact on the battery cell.

[0012] According to one embodiment of the present application, the wall portion has an inner surface and an outer surface arranged opposite to each other in the thickness direction; the wall portion is provided with a first recessed portion recessed from the inner surface, and a portion of the wall portion corresponding to the bottom surface of the first recess forms a weak portion; the first protective layer is attached to the outer surface and covers the weak portion.

[0013] In these optional embodiments, the phenomenon of dirt and grime accumulating in the first recessed portion on the wall during use can be reduced.

[0014] According to one embodiment of the present application, the wall portion has an inner surface and an outer surface arranged opposite to each other in the thickness direction; the wall portion is provided with a second recessed portion recessed from the outer surface, and a portion of the wall portion corresponding to the bottom surface of the second recess forms a weak portion; at least a portion of the first protective layer is arranged in the second recess.

[0015] In these alternative embodiments, since the weak portion will burst and crack when subjected to a certain pressure, and since it is subjected to stress after processing and is relatively fragile compared to other parts of the wall, a second recessed portion is provided on the outer surface to prevent the weak portion from being directly contacted, thereby providing a certain degree of protection for the weak portion. Furthermore, the second recessed portion on the outer surface is relatively easy to process, thereby reducing processing and manufacturing costs.

[0016] According to one embodiment of the present application, the first protection layer is flush with an edge of the opening of the second recess.

[0017] In these optional embodiments, the weak portion cooperates with the first protective layer, and the first protective layer is flush with the edge of the opening of the second recess, so that the entire outer surface of the battery cell is flush, thereby not affecting the assembly of the battery cell.

[0018] According to one embodiment of the present application, the wall portion has an inner surface and an outer surface arranged relative to each other in the thickness direction; the wall portion includes a reinforcing portion protruding from the inner surface, and a first groove recessed relative to the outer surface is provided at a position of the wall portion corresponding to the reinforcing portion; the battery cell also includes a second protective layer, at least a portion of the second protective layer is arranged in the first groove.

[0019] In these optional embodiments, when the wall portion is deformed, the reinforcement portion can reduce the effect of the deformation on the weak portion, thereby reducing the risk of liquid leakage from the weak portion.

[0020] According to one embodiment of the present application, the wall portion has an inner surface and an outer surface arranged opposite to each other in the thickness direction; the wall portion includes a reinforcing portion protruding from the outer surface, and the wall portion is provided with a second groove sunken relative to the inner surface at a position corresponding to the reinforcing portion; the battery cell also includes a second protective layer, which is attached to the outer surface and covers the reinforcing portion.

[0021] These optional embodiments not only enhance structural strength but also reduce the internal space occupied by the battery cell or the battery, thereby improving the battery's energy density. The outwardly protruding reinforcement absorbs external impact energy, reducing the impact on the weak portion and, to a certain extent, preventing damage to the weak portion.

[0022] According to one embodiment of the present application, the wall portion further includes a main body portion, the weak portion is connected to the main body portion, and the first protective layer further covers at least a portion of the main body portion.

[0023] In these optional embodiments, when the weak portion is processed and manufactured, the edge area of ​​the weak portion will be affected. Therefore, the first protective layer is designed to cover the weak portion and extend toward the main portion. The first protective layer covers at least a portion of the main portion to reduce corrosion in the edge area of ​​the weak portion.

[0024] According to one embodiment of the present application, in the radial direction of the wall portion, a size of an area of ​​the main body portion covered by the first protective layer is greater than or equal to 0.1 mm.

[0025] According to one embodiment of the present application, the thickness of the first protective layer is less than or equal to the thickness of the weak portion.

[0026] In these optional embodiments, the first protective layer has an adapted thickness, which can both meet the corrosion resistance and reduce the impact on the bursting pressure of the weak part.

[0027] According to one embodiment of the present application, the thickness of the first protective layer is greater than or equal to 10 μm.

[0028] In these optional embodiments, the first protective layer needs to meet working condition tests such as high temperature resistance, high and low temperature alternating humidity and heat, and salt spray resistance. Therefore, the thickness of the first protective layer is greater than or equal to 10 μm, and the first protective layer can meet the working condition test.

[0029] According to one embodiment of the present application, the strength of the first protective layer is less than or equal to the strength of the weak portion.

[0030] In these optional embodiments, such an arrangement can reduce the impact on the bursting pressure of the weak portion.

[0031] According to an embodiment of the present application, the material of the first protective layer is selected from one of polyacrylate, polyurethane or epoxy resin.

[0032] In these optional embodiments, these specific optional materials are used so that the first protective layer has better corrosion resistance.

[0033] According to one embodiment of the present application, the housing includes and end cover; the shell has an opening; the end cover closes the opening; and the wall portion is the end cover or a wall of the shell.

[0034] In these optional embodiments, the wall portion can be an end cover, a bottom wall of the shell, or a side wall of the shell. The weak portion is arranged near the edge of the end cover, bottom wall or side wall, and is not prone to fatigue failure under the action of air pressure, which is beneficial to reducing the risk of premature opening of the weak portion and allowing the battery cell to operate normally.

[0035] In a second aspect, the present application provides a battery comprising the aforementioned battery cell.

[0036] In a third aspect, the present application provides an electrical device comprising a plurality of battery cells or batteries as described above, wherein the batteries are used to provide electrical energy.

[0037] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0039] FIG1 is a schematic structural diagram of a vehicle provided in one embodiment of the present application;

[0040] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0041] FIG3 is a schematic structural diagram of a battery cell provided in one embodiment of the present application;

[0042] FIG4 is an exploded view of a battery cell provided in one embodiment of the present application;

[0043] FIG5 is a bottom view of a wall portion of a battery cell provided in one embodiment of the present application;

[0044] FIG6 is a cross-sectional view of a wall portion of a battery cell provided in one embodiment of the present application;

[0045] FIG7 is a schematic structural diagram of FIG6 at AA;

[0046] FIG8 is a schematic structural diagram of a wall portion of a battery cell having a first protective layer and a second protective layer provided in one embodiment of the present application;

[0047] FIG9 is a top view of a wall portion of a battery cell provided in another embodiment of the present application;

[0048] FIG10 is a cross-sectional view of a wall portion of a battery cell provided in another embodiment of the present application;

[0049] FIG11 is a schematic structural diagram of FIG10 at position BB;

[0050] FIG12 is a schematic structural diagram of a wall portion of a battery cell having a first protective layer and a second protective layer provided in another embodiment of the present application;

[0051] FIG13 is a schematic structural diagram of a battery cell housing provided in one embodiment of the present application;

[0052] FIG14 is a cross-sectional view of a housing of a battery cell provided in one embodiment of the present application;

[0053] FIG15 is an enlarged structural diagram of point C in FIG14 .

[0054] The drawings are not necessarily drawn to scale.

[0055] Explanation of the accompanying drawings: 1000, vehicle; 100, battery; 200, controller; 300, motor; 10, battery cell; 20, cover; 30, lower box; 1, outer shell; 11, wall; 111, inner surface; 112, outer surface; 113, first recess; 114, second recess; 12, weak portion; 13, reinforcement portion; 131, first groove; 132, second groove; 14, main body; 15, shell; 16, end cover; 2, first protective layer; 3, second protective layer. DETAILED DESCRIPTION

[0056] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0057] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0058] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0059] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0060] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0061] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0062] The term "plurality" used in this application refers to two or more (including two).

[0063] In this application, battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, and the embodiments of this application are not limited thereto. Battery cells may be cylindrical, flat, rectangular, or in other shapes, and the embodiments of this application are not limited thereto.

[0064] The battery mentioned in the embodiments of the present application may include one or more battery cells to provide a single physical module with higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel or in hybrid through a busbar.

[0065] In some embodiments, the battery may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0066] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0067] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0068] In related technologies, a weak portion is formed in the battery cell casing to directly serve as an explosion-proof valve. This weak portion is placed inside or outside the casing through stamping or milling. This can damage the outer coating of the casing. During subsequent transportation, storage, and use of the battery cell, the weak portion can rust, affecting the burst pressure and reducing the reliability of the battery cell. The above statements are intended only to provide background information related to this application and do not necessarily constitute prior art.

[0069] In view of the above problems, the battery cell provided in the present application includes a shell and a first protective layer. The shell has a wall portion, and the wall portion is provided with a weak portion. The weak portion ruptures when the internal pressure or temperature of the battery cell reaches a threshold value. The first protective layer covers at least part of the weak portion to form protection for the weak portion, reduce corrosion of the weak portion, and improve the impact on the bursting pressure of the weak portion.

[0070] Batteries can be used in vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys and power tools, etc. Vehicles can be fuel vehicles, gas vehicles or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles, etc.; spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned tab production equipment.

[0071] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0072] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device according to an embodiment of the present application.

[0073] As shown in FIG1 , one embodiment of the present application provides a vehicle 1000 . Vehicle 1000 can be a fuel-powered vehicle, a gas-powered vehicle, or a new energy vehicle. A new energy vehicle can be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, among others. In one embodiment of the present application, vehicle 1000 includes a motor 300 , a controller 200 , and a battery 100 . Controller 200 controls battery 100 to power motor 300 . Motor 300 is connected to wheels via a transmission mechanism, thereby driving vehicle 1000 . Battery 100 can serve as the driving power source for vehicle 1000 , replacing or partially replacing fuel or natural gas in providing driving power for vehicle 1000 . In one example, battery 100 can be located at the bottom, front, or rear of vehicle 1000 . Battery 100 can be used to power vehicle 1000 . In one example, battery 100 can serve as the operating power source for vehicle 1000 , serving as the electrical system of vehicle 1000 . Specifically, battery 100 can be used to power vehicle 1000 during startup, navigation, and operation.

[0074] Please refer to Figure 2, which is an exploded view of the battery provided in some embodiments of the present application. The battery 100 includes a housing and a battery cell. In some embodiments, the housing may include a cover 20 and a lower housing 30, wherein the cover 20 and the lower housing 30 cover each other, and the cover 20 and the lower housing 30 jointly define a storage space for accommodating the battery cell. The lower housing 30 may be a hollow structure with one end open, and the cover 20 may be a plate-like structure, with the cover 20 covering the open side of the lower housing 30 so that the cover 20 and the lower housing 30 jointly define a storage space; the cover 20 and the lower housing 30 may also be hollow structures with one side open, with the open side of the cover 20 covering the open side of the lower housing 30. Of course, the housing formed by the cover 20 and the lower housing 30 may be of various shapes, such as a cylinder, a cuboid, etc.

[0075] Please refer to Figures 2 to 4. Figure 3 is a schematic structural diagram of a battery cell provided in an embodiment of the present application; Figure 4 is an exploded view of a battery cell provided in an embodiment of the present application. In the battery 100, there can be multiple battery cells 10, and the multiple battery cells 10 can be connected in series, in parallel, or in mixed connection. Mixed connection means that multiple battery cells 10 are connected in series and in parallel. Multiple battery cells 10 can be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple battery cells 10 is accommodated in a box; of course, the battery 100 can also be a battery module formed by first connecting multiple battery cells 10 in series, in parallel, or in mixed connection, and then the multiple battery modules are connected in series, in parallel, or in mixed connection to form a whole, and accommodated in a box. The battery 100 can also include other structures. For example, the battery 100 can also include a busbar component for realizing electrical connection between multiple battery cells.

[0076] Each battery cell can be a lithium-ion battery cell, a lithium-sulfur battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, but is not limited thereto. The battery cell can be cylindrical, flat, rectangular, or in other shapes.

[0077] Referring to Figures 5 to 8, Figure 5 is a bottom view of the wall of a battery cell provided in an embodiment of the present application; Figure 6 is a cross-sectional view of the wall of a battery cell provided in an embodiment of the present application; Figure 7 is a structural schematic diagram of Figure 6 at AA; Figure 8 is a structural schematic diagram of the wall of a battery cell having a first protective layer and a second protective layer provided in an embodiment of the present application.

[0078] In a first aspect, as shown in Figures 5 to 8 , the present application provides a battery cell 10, comprising a housing 1 and a first protective layer 2. The housing 1 has a wall 11, which is provided with a weak portion 12. The weak portion 12 is configured to rupture when the internal pressure or temperature of the battery cell 10 reaches a threshold. The first protective layer 2 is disposed on the wall 11 and covers at least a portion of the weak portion 12.

[0079] The housing 1 is a component that isolates the internal environment of the battery cell 10 from the external environment. The internal environment formed by the housing 1 can be used to accommodate the electrode assembly, electrolyte and other components.

[0080] The weak portion 12 is a structure for rupturing when the internal pressure or temperature of the battery cell 10 reaches a threshold value to release the internal pressure of the battery cell 10 and reduce the risk of explosion or fire of the battery cell 10 .

[0081] The housing 1 has a plurality of walls, such as a bottom wall, side walls, etc. Each wall of the housing 1 can serve as a wall portion 11 .

[0082] Exemplarily, the bottom wall may be the wall portion 11 , and in this case, the weak portion 12 is provided on the bottom wall.

[0083] Exemplarily, the side wall may be the wall portion 11 , and in this case, the weak portion 12 is provided on the side wall.

[0084] Exemplarily, the end cover 16 may serve as a wall portion 11 alone, and in this case, the weak portion 12 is provided on the end cover 16 .

[0085] It should be noted that the housing 1 may have a plurality of wall portions 11, and each wall portion 11 is provided with a weak portion 12. For example, the bottom wall and the side wall are both wall portions 11, and in this case, the bottom wall and the side wall are both provided with a weak portion 12.

[0086] The first protective layer 2 is disposed on the wall portion 11 and covers at least a portion of the weak portion 12 to protect the weak portion 12 , reduce corrosion of the weak portion 12 , and improve the impact on the bursting pressure of the weak portion 12 .

[0087] In the embodiment of the present application, the first protective layer 2 covers at least a portion of the weak portion 12. It can be understood that the first protective layer 2 covers a portion of the weak portion 12, or the first protective layer 2 covers the entire weak portion 12. In addition, the first protective layer 2 may also cover other parts of the wall portion 11 except the weak portion 12.

[0088] Specifically, the first protective layer 2 is an anti-corrosion protective layer, thereby reducing water vapor leakage.

[0089] In an embodiment of the present application, the first protective layer 2 is arranged on the wall portion 11. Specifically, the wall portion 11 has an outer surface 112 and an inner surface 111, and the first protective layer 2 is arranged on the outer surface 112; or, the first protective layer 2 is arranged on the inner surface 111, and both the outer surface 112 and the inner surface 111 are provided with the first protective layer 2.

[0090] The battery cell 10 provided in the present application includes an outer shell 1 and a first protective layer 2. The outer shell 1 has a wall portion 11, and the wall portion 11 is provided with a weak portion 12. The weak portion 12 ruptures when the internal pressure or temperature of the battery cell 10 reaches a threshold value. The first protective layer 2 covers at least a portion of the weak portion 12, forming a protective layer with the weak portion 12, reducing corrosion of the weak portion 12, and improving the impact of the bursting pressure of the weak portion 12. In addition, the first protective layer 2 also provides a certain degree of buffering effect on the weak portion 12, thereby reducing the possibility of the weak portion 12 rupturing when the internal pressure of the battery cell 10 reaches a threshold value, thereby scratching or injuring people or objects. It can also effectively alleviate the situation where the weak portion 12 is prematurely actuated and ruptured during use. Therefore, it is beneficial to improve the service life and reliability of the battery cell 10 with the first protective layer 2.

[0091] According to one embodiment of the present application, the first protective layer 2 is located outside the wall portion 11 .

[0092] In an embodiment of the present application, the wall portion 11 has an inner surface 111 and an outer surface 112 arranged opposite to each other in the thickness direction. The inner surface 111 may be provided with a weak portion 12, or the outer surface 112 may be provided with a weak portion 12; or both the inner surface 111 and the outer surface 112 are provided with a weak portion 12.

[0093] Exemplarily, the inner surface 111 may be provided with a weak portion 12 , the first protective layer 2 is located outside the wall portion 11 , and a projection of the first protective layer on the wall portion 11 along the thickness direction at least overlaps with the weak portion 12 .

[0094] For example, the outer surface 112 may be provided with a weakened portion 12 , and the first protective layer 2 is attached to the weakened portion 12 .

[0095] The weak portion 12 is a weak portion 12 of the housing 1 . During the manufacturing process, a certain area of ​​the housing 1 is usually processed into a thinner weak portion 12 .

[0096] For example, a tool is used to cut away a certain thickness of material from the wall portion 11 to form the weak portion 12 .

[0097] Exemplarily, a certain area of ​​the wall portion 11 is punched into a thinner area to form the weak portion 12 .

[0098] Exemplarily, a certain area of ​​the wall portion 11 is milled into a thinner area to form the weak portion 12 .

[0099] Optionally, notches or grooves are provided on the wall portion 11 to form a weak portion 12 .

[0100] In these optional embodiments, the first protective layer 2 is located outside the wall portion 11, which not only achieves an anti-corrosion effect but also does not occupy the space inside the battery cell 10, thereby increasing the energy density of the battery cell 10. In addition, the first protective layer 2 is disposed on the outside of the battery cell 10. When the battery cell 10 is subjected to an impact force, the first protective layer 2 on the outside of the battery cell 10 can disperse the force, thereby reducing the impact on the battery cell 10.

[0101] According to one embodiment of the present application, as shown in Figures 5 to 8 , the wall portion 11 has an inner surface 111 and an outer surface 112 disposed opposite each other in the thickness direction. The wall portion 11 is provided with a first recessed portion 113 recessed from the inner surface 111. A portion of the wall portion 11 corresponding to the bottom surface of the first recessed portion 113 forms a weakened portion 12. The first protective layer 2 is attached to the outer surface 112 and covers the weakened portion 12.

[0102] The inner surface 111 and the outer surface 112 of the wall portion 11 are two surfaces that face each other in the thickness direction of the wall portion 11, and the distance between the inner surface 111 and the outer surface 112 is the thickness of the wall portion 11. The outer surface 112 faces the outside of the battery cell 10, and the inner surface 111 faces the inside of the battery cell 10.

[0103] In the embodiment of the present application, the wall portion 11 is provided with a first recessed portion 113 recessed from the inner surface 111. The first recessed portion 113 can have various shapes, such as arc, H-shape, U-shape, annular shape, etc. The scored first recessed portion 113 on the wall portion 11 can be formed by various methods, such as milling, stamping, cold heading, etc.

[0104] For example, taking the use of stamping to form the first recess 113 as an example, the first recess 113 can be stamped on the wall 11 along the direction from the inner surface 111 to the outer surface 112, and the portion of the wall 11 corresponding to the bottom surface of the first recess 113 forms a weak portion 12.

[0105] In an embodiment of the present application, the portion of the wall 11 corresponding to the bottom surface of the first recess 113 forms a weak portion 12 , the weak portion 12 located on the outside is flush with other portions of the outer surface 112 of the wall 11 , and the first protective layer 2 is attached to the outside of the weak portion 12 .

[0106] In these optional embodiments, the phenomenon of dirt and grime accumulating in the first recess 113 on the wall portion 11 during use can be reduced.

[0107] Referring to Figures 9 to 12, Figure 9 is a top view of the wall of a battery cell provided in another embodiment of the present application; Figure 10 is a cross-sectional view of the wall of a battery cell provided in another embodiment of the present application; Figure 11 is a structural schematic diagram at BB of Figure 10; and Figure 12 is a structural schematic diagram of the wall of a battery cell having a first protective layer and a second protective layer provided in another embodiment of the present application.

[0108] According to one embodiment of the present application, as shown in Figures 9 to 12 , the wall portion 11 has an inner surface 111 and an outer surface 112 disposed opposite each other in the thickness direction. A second recess 114 is provided on the wall portion 11, recessed from the outer surface 112. A portion of the wall portion 11 corresponding to the bottom surface of the second recess 114 forms the weakened portion 12. At least a portion of the first protective layer 2 is disposed within the second recess 114.

[0109] In the embodiment of the present application, at least a portion of the first protective layer 2 is disposed within the second recess 114. The first protective layer 2 may fill a portion of the second recess 114. It can be understood that the maximum thickness of the first protective layer 2 is less than the depth of the second recess 114. The first protective layer 2 may also completely fill the second recess 114.

[0110] In these optional embodiments, since the weak portion 12 will burst and crack when subjected to a certain pressure, and since it is subjected to stress after processing and is relatively fragile compared to other parts of the wall portion 11, a second recessed portion 114 is provided on the outer surface 112 to prevent the weak portion 12 from being directly contacted, thereby providing a certain degree of protection for the weak portion 12. Furthermore, the second recessed portion 114 on the outer surface 112 is relatively easy to process, thereby reducing processing and manufacturing costs.

[0111] According to one embodiment of the present application, the first protection layer 2 is flush with the edge of the opening of the second recess 114 .

[0112] In the embodiment of the present application, the first protective layer 2 completely fills the second recess 114 , and the first protective layer 2 is flush with the edge of the opening of the second recess 114 .

[0113] In these optional embodiments, the weak portion 12 cooperates with the first protective layer 2 , and the first protective layer 2 is flush with the edge of the opening of the second recess 114 , so that the overall outer surface 112 of the battery cell 10 is flush, thereby not affecting the assembly of the battery cell 10 .

[0114] According to one embodiment of the present application, as shown in Figures 7 and 8 , the wall portion 11 has an inner surface 111 and an outer surface 112 disposed opposite each other in the thickness direction. The wall portion 11 also includes a reinforcement portion 13 protruding from the inner surface 111, and a first groove 131 is formed in the wall portion 11 at a position corresponding to the reinforcement portion 13 and recessed relative to the outer surface 112. The battery cell 10 also includes a second protective layer 3, at least partially disposed within the first groove 131.

[0115] In an embodiment of the present application, the reinforcement portion 13 is provided to protrude from the inner surface 111 to form a convex body on the inner surface 111, and the wall portion 11 is provided with a first groove 131 recessed relative to the outer surface 112 at a position corresponding to the reinforcement portion 13, thereby improving the structural strength of the wall portion 11 without changing the thickness of the wall portion 11.

[0116] Exemplarily, a portion of the wall portion 11 is punched toward the inner surface 111 through the outer surface 112 , forming a convex body on the inner surface 111 and a first groove 131 on the outer surface 112 , so as to form the reinforcement portion 13 .

[0117] The battery cell 10 further includes a second protective layer 3 , which is disposed on the outside and at least partially located in the first groove 131 .

[0118] In the embodiment of the present application, at least a portion of the second protective layer 3 is disposed within the first groove 131. The second protective layer 3 may fill a portion of the first groove 131. It can be understood that the maximum thickness of the second protective layer 3 is less than the groove depth of the first groove 131. The second protective layer 3 may also completely fill the first groove 131.

[0119] Optionally, the second protection layer 3 is flush with the edge of the opening of the first groove 131 .

[0120] Exemplarily, the second protective layer 3 has the same thickness as the first protective layer 2 .

[0121] In these optional embodiments, when the wall portion 11 is deformed, the reinforcement portion 13 can reduce the effect of the deformation on the weak portion 12 , thereby reducing the risk of liquid leakage from the weak portion 12 .

[0122] According to one embodiment of the present application, as shown in Figures 11 and 12, the wall portion 11 has an inner surface 111 and an outer surface 112 arranged opposite to each other in the thickness direction. The wall portion 11 also includes a reinforcing portion 13 protruding from the outer surface 112, and the wall portion 11 is provided with a second groove 132 recessed relative to the inner surface 111 at a position corresponding to the reinforcing portion 13. The battery cell 10 also includes a second protective layer 3, which is attached to the outer surface 112 and the reinforcing portion 13.

[0123] In these alternative embodiments, not only can the structural strength be enhanced, but the internal space occupied by the battery cell 10 or the battery itself can also be reduced, thereby improving the battery's energy density. When subjected to an external impact, the outwardly protruding reinforcement portion 13 can first absorb the energy of the external impact, thereby reducing the impact on the location of the weak portion 12 and, to a certain extent, preventing damage to the weak portion 12 due to the external impact.

[0124] According to one embodiment of the present application, the wall portion 11 further includes a main body portion 14 , the weak portion 12 is connected to the main body portion 14 , and the first protective layer 2 further covers at least a portion of the main body portion 14 .

[0125] In the embodiment of the present application, the wall portion 11 includes a weak portion 12 and a main portion 14, wherein the weak portion 12 is connected to the main portion 14. The first protective layer 2 includes the main portion 14 and an extension portion, wherein the main portion 14 is connected to the extension portion and extends toward the main portion 14. The main portion 14 covers the weak portion 12, and the extension portion covers at least a portion of the main portion 14. The extension portion may cover a portion of the main portion 14, or may cover the entire main portion 14.

[0126] Optionally, in the radial direction of the wall portion, the size of the area of ​​the main body portion 14 covered by the first protective layer 2 is greater than or equal to 0.1 mm.

[0127] In these optional embodiments, when the weak portion 12 is processed and manufactured, the edge area of ​​the weak portion 12 will be affected. Therefore, the first protective layer 2 is designed to cover the weak portion 12 and extend toward the main portion 14. The first protective layer 2 covers at least a portion of the main portion 14 to reduce corrosion in the edge area of ​​the weak portion 12.

[0128] According to one embodiment of the present application, the thickness of the first protective layer 2 is less than or equal to the thickness of the weak portion 12 .

[0129] Exemplarily, the wall portion 11 has an inner surface 111 and an outer surface 112 disposed opposite each other in the thickness direction. The wall portion 11 is provided with a second recessed portion 114 recessed from the outer surface 112. A portion of the wall portion 11 corresponding to the bottom surface of the second recessed portion 114 forms the weak portion 12. The depth of the second recessed portion 114 is less than the thickness of the weak portion 12. The thickness of the first protective layer 2 is less than the depth of the second recessed portion 114.

[0130] In these optional embodiments, the first protective layer 2 has an adapted thickness, which can meet the corrosion resistance requirements while reducing the impact on the bursting pressure of the weak portion 12 .

[0131] According to one embodiment of the present application, the thickness of the first protective layer 2 is greater than or equal to 10 μm.

[0132] In these optional embodiments, the first protective layer 2 needs to meet working condition tests such as high temperature resistance, high and low temperature alternating resistance, humidity and heat resistance, and salt spray resistance. Therefore, the thickness of the first protective layer 2 is greater than or equal to 10 μm, and the first protective layer 2 can meet the working condition test.

[0133] According to one embodiment of the present application, the thickness of the first protective layer 2 is 10 μm<d≤500 μm.

[0134] In some embodiments of the present application, the thickness of the first protective layer 2 is: 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm, 270 μm, 280 μm, 290 μm, 300 μm, 310 μm, 320 μm, 330 μm, 340 μm, 350 μm, 360 μm, 370 μm, 380 μm, 390 μm, 400 μm, 410 μm, 420 μm, 430 μm, 440 μm, 450 μm, 460 μm, 470 μm, 480 μm, 490 μm, 500 μm or in other ranges consisting of any two of the above endpoints.

[0135] Specifically, the thickness of the first protective layer 2 is 50 μm<d≤200 μm.

[0136] In these optional embodiments, the first protective layer 2 has an appropriate thickness, which can also reduce the usage of the first protective layer 2 to reduce costs.

[0137] According to one embodiment of the present application, the strength of the first protective layer 2 is less than or equal to the strength of the weak portion 12 .

[0138] In the embodiments of the present application, the strength is tensile strength, which can be measured using a tensile test method (such as GB / T228.1-2010 "Tensile Test Method for Metal Materials").

[0139] In these optional embodiments, such an arrangement can reduce the impact on the bursting pressure of the weak portion 12 .

[0140] According to an embodiment of the present application, the material of the first protective layer 2 is selected from one of polyacrylate, polyurethane or epoxy resin.

[0141] In some embodiments of the present application, the material of the first protective layer 2 is selected from polymer materials such as polyacrylate, polyurethane or epoxy resin, so that the first protective layer 2 has high anti-corrosion performance and reduces water vapor leakage.

[0142] Specifically, the raw materials of the first protective layer 2 are prepared into a slurry with a viscosity of 1 cps to 1000 cps, and applied to the surface of the weak portion 12 by spraying, printing, dispensing, etc. The adhesion of the first protective layer 2 can also be improved by laser treatment, plasma treatment, etc.

[0143] Exemplarily, the level of adhesion between the first protective layer 2 and the weak portion 12 is greater than or equal to level 1.

[0144] Exemplarily, the material of the second protective layer 3 is the same as that of the first protective layer 2 .

[0145] In these optional embodiments, these specific optional materials are used to make the first protective layer 2 have better corrosion resistance.

[0146] 13 to 15 , FIG13 is a schematic structural diagram of a battery cell shell according to an embodiment of the present application; FIG14 is a cross-sectional view of a battery cell shell according to an embodiment of the present application; and FIG15 is an enlarged schematic structural diagram of point C in FIG14 .

[0147] According to one embodiment of the present application, as shown in Figures 4 and 13 to 15 , the housing 1 includes an end cap 16 . The housing 15 has an opening. The end cap 16 closes the opening. The wall 11 is the end cap 16 or a wall of the housing 15 .

[0148] Exemplarily, as shown in FIG. 13 to FIG. 15 , the wall portion 11 is a wall of the housing 15 .

[0149] The housing 1 includes a shell 15 and an end cover 16 , and the shell 15 and the end cover 16 cooperate to form the housing 1 .

[0150] The end cap 16 refers to a component that covers the opening of the shell 15 to isolate the internal environment of the battery cell 10 from the external environment. Without limitation, the shape of the end cap 16 can be adapted to the shape of the shell 15 to match the shell 15. Optionally, the end cap 16 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 16 is not easily deformed when squeezed or collided, so that the battery cell 10 can have a higher structural strength and improved safety performance. Functional components such as electrode terminals can be provided on the end cap 16. The electrode terminal can be used to electrically connect to the electrode assembly for outputting or inputting electrical energy of the battery cell 10. In some embodiments, the end cap 16 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell 10 reaches a threshold. The material of the end cap 16 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose any special restrictions on this. In some embodiments, an insulating member may be provided inside the end cap 16 to isolate the electrical connection components in the housing 15 from the end cap 16 to reduce the risk of short circuit.

[0151] The housing 15 is a component that cooperates with the end cap 16 to form the internal environment of the battery cell 10. This internal environment can be used to accommodate the electrode assembly, electrolyte, and other components. The housing 15 and end cap 16 can be separate components. An opening can be provided in the housing 15, and the end cap 16 is placed over the opening to form the internal environment of the battery cell 10. Alternatively, the end cap 16 and housing 15 can be integrated. Specifically, the end cap 16 and housing 15 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 15 needs to be enclosed, the end cap 16 is placed over the housing 15. The housing 15 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 15 can be determined based on the specific shape and size of the electrode assembly. The housing 15 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any specific limitations on this.

[0152] In these optional embodiments, the wall portion 11 can be the end cover 16, the bottom wall of the shell 15, or the side wall of the shell 15. The weak portion 12 is arranged near the edge of the end cover 16, the bottom wall or the side wall, and is not prone to fatigue failure under the action of air pressure, which is beneficial to reducing the risk of the weak portion 12 opening prematurely, so that the battery cell 10 can operate normally.

[0153] A battery cell 10 generally includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (e.g., lithium ions) are intercalated and released between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0154] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0155] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0156] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, silver-surface-treated stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0157] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and modified compounds thereof. However, this application is not limited to these materials; other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used singly or in combination of two or more.

[0158] In some embodiments, the positive electrode may be a carbon foam or a metal foam. The metal foam may be nickel foam, copper foam, aluminum foam, or an alloy foam, among others. When the metal foam is used as the positive electrode, the surface of the metal foam may or may not be provided with a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled and / or deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0159] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0160] As an example, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium with a silver surface treatment may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0161] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0162] 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 or both of the two facing surfaces of the negative electrode current collector.

[0163] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate.

[0164] In some embodiments, the negative electrode may be made of carbon foam or metal foam. The metal foam may be nickel foam, copper foam, aluminum foam, or alloy foam. When the metal foam is used as the negative electrode sheet, the surface of the metal foam may or may not be provided with a negative electrode active material.

[0165] As an example, the negative electrode current collector may be filled with or / and deposited with a lithium source material, potassium metal, or sodium metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0166] 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.

[0167] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0168] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0169] As an example, the main material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics.

[0170] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0171] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on needs. The electrolyte can be liquid, gel, or solid.

[0172] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0173] In some embodiments, the electrode assembly is a laminate structure.

[0174] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0175] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0176] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0177] As an example, a plurality of separators may be provided, each of which is disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0178] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0179] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0180] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0181] In some embodiments, the battery cell 10 further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte may be selected based on needs. The electrolyte may be liquid, gel, or solid.

[0182] In a second aspect, the present application provides a battery comprising the aforementioned battery cell.

[0183] In a third aspect, the present application provides an electrical device comprising a plurality of battery cells 10 or batteries as described above, wherein the battery cells or batteries are used to provide electrical energy.

[0184] According to some embodiments of the present application, referring to Figures 5 to 8 , a battery cell 10 is provided. The battery cell 10 includes an outer shell 1, a first protective layer 2, and a second protective layer 3. The outer shell 1 includes an end cap 16. The housing 15 has an opening, and the end cap 16 seals the opening. The end cap 16 has a wall portion 11, which includes a main body 14, a reinforcement portion 13, and a weakened portion 12. The main body 14 connects the reinforcement portion 13 and the weakened portion 12. The weakened portion 12 is configured to rupture when the internal pressure or temperature of the battery cell 10 reaches a threshold. The wall portion 11 has an inner surface 111 and an outer surface 112 disposed opposite each other in the thickness direction. The wall portion 11 has a first recessed portion 113 recessed from the inner surface 111. The portion of the wall portion 11 corresponding to the bottom surface of the first recessed portion 113 forms the weakened portion 12. The first protective layer 2 is attached to the outer surface 112 and covers the weakened portion 12. It extends toward the main body 14, covering at least a portion of the main body 14. Along the radial direction of the wall portion 11, the area of ​​the main body 14 covered by the first protective layer 2 is greater than or equal to 0.1 mm. The thickness of the first protective layer 2 is 20 μm. The strength of the first protective layer 2 is less than or equal to the strength of the weak portion 12. The reinforcement portion 13 is provided protruding from the inner surface 111. The wall portion 11 has a first groove 131 recessed relative to the outer surface 112 at a position corresponding to the reinforcement portion 13. At least a portion of the second protective layer 3 is disposed within the first groove 131. The second protective layer 3 is flush with the edge of the opening of the first groove 131.

[0185] The battery cell 10 provided in the present application includes an outer shell 1 and a first protective layer 2. The outer shell 1 has a wall portion 11, and the wall portion 11 is provided with a weak portion 12. The weak portion 12 ruptures when the internal pressure or temperature of the battery cell 10 reaches a threshold value. The first protective layer 2 covers at least a portion of the weak portion 12, forming a protective layer with the weak portion 12, reducing corrosion of the weak portion 12, and improving the impact of the bursting pressure of the weak portion 12. In addition, the first protective layer 2 also provides a certain degree of buffering effect on the weak portion 12, thereby reducing the possibility of the weak portion 12 rupturing when the internal pressure of the battery cell 10 reaches a threshold value, thereby scratching or injuring people or objects. It can also effectively alleviate the situation where the weak portion 12 is prematurely actuated and ruptured during use. Therefore, it is beneficial to improve the service life and reliability of the battery cell 10 with the first protective layer 2.

[0186] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A battery cell, comprising: a housing having a wall portion, the wall portion being provided with a weakened portion, the weakened portion being configured to rupture when an internal pressure or temperature of the battery cell reaches a threshold value; The first protective layer is disposed on the wall portion and covers at least a portion of the weak portion.

2. The battery cell according to claim 1, wherein: The first protective layer is located on the outer side of the wall portion.

3. The battery cell according to claim 2, wherein: The wall portion has an inner surface and an outer surface arranged opposite to each other in the thickness direction; The wall portion is provided with a first recessed portion sunken from the inner surface, and a portion of the wall portion corresponding to the bottom surface of the first recessed portion forms the weak portion; The first protective layer is attached to the outer surface and covers the weak portion.

4. The battery cell according to claim 2, wherein: The wall portion has an inner surface and an outer surface arranged opposite to each other in the thickness direction; The wall portion is provided with a second recessed portion sunken from the outer surface, and a portion of the wall portion corresponding to the bottom surface of the second recessed portion forms the weak portion; At least a portion of the first protection layer is disposed in the second recess.

5. The battery cell according to claim 4, wherein: The first protection layer is flush with an edge of the opening of the second recess.

6. The battery cell according to claim 2, wherein: The wall portion has an inner surface and an outer surface arranged opposite to each other in the thickness direction; The wall portion further comprises a reinforcement portion protruding from the inner surface, and the wall portion is provided with a first groove recessed relative to the outer surface at a position corresponding to the reinforcement portion; The battery cell further includes a second protection layer, at least a portion of which is disposed in the first groove.

7. The battery cell according to claim 2, wherein: The wall portion has an inner surface and an outer surface arranged opposite to each other in the thickness direction; The wall portion further includes a reinforcement portion protruding from the outer surface, and the wall portion is A second groove is provided at a position corresponding to the strong part and is recessed relative to the inner surface; The battery cell further includes a second protective layer attached to the outer surface and covering the reinforcing portion.

8. The battery cell according to any one of claims 1 to 7, wherein: The wall portion further includes a main body portion, the weak portion is connected to the main body portion, and the first protective layer also covers at least a portion of the main body portion.

9. The battery cell according to claim 8, wherein: In the radial direction of the wall portion, a size of a region of the main body portion covered by the first protective layer is greater than or equal to 0.1 mm.

10. The battery cell according to any one of claims 1 to 9, wherein: The thickness of the first protective layer is less than or equal to the thickness of the weak portion.

11. The battery cell according to claim 10, wherein: The thickness of the first protective layer is greater than or equal to 10 μm.

12. The battery cell according to any one of claims 1 to 11, wherein: The strength of the first protective layer is less than or equal to the strength of the weak portion.

13. The battery cell according to any one of claims 1 to 12, wherein: The material of the first protective layer is selected from polyacrylate, polyurethane or epoxy resin.

14. The battery cell according to any one of claims 1 to 13, wherein: The housing comprises: a housing having an opening; an end cap for closing the opening; The wall portion is the end cover or a wall of the housing.

15. A battery comprising a plurality of battery cells according to any one of claims 1 to 14. 16 . An electrical device comprising a plurality of battery cells according to claim 1 or a battery according to claim 15 , wherein the battery cells or the battery are used to provide electrical energy.

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