Battery cell, battery, and electric device

Abstract

A battery cell, a battery, and an electric device. The battery cell comprises a casing, a pressure relief structure, and an electrode assembly. The casing is provided with a first wall. The pressure relief structure is disposed on the first wall. The electrode assembly is a wound electrode assembly and is disposed in the casing, and the electrode assembly comprises a flat portion and a first bending portion. Along a first direction, the first bending portion is disposed on the side of the flat portion facing the first wall. A first boundary line is provided between the first bending portion and the flat portion. The distance between the first boundary line and the first wall is L, wherein L≥5 mm. The first direction is perpendicular to the axial direction of the electrode assembly.

Description

Battery cells, batteries and electrical devices Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0002] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, batteries, as the power source of electric vehicles, play an irreplaceable and important role. As core components of new energy vehicles, batteries have high requirements in terms of both energy density and reliability.

[0003] In related technologies, a pressure relief structure is generally provided in the battery cell, and pressure is relieved through the pressure relief structure when the battery cell experiences thermal runaway. However, in some technologies, when the battery cell is in use, the pressure relief structure may be easily pulled and cracked due to expansion and deformation, thereby affecting the reliability of the battery cell.

[0004] Summary of the Invention

[0005] The present application proposes a battery cell, a battery, and an electrical device, which can improve the reliability of the battery cell while taking into account the energy density of the battery cell to a certain extent.

[0006] In the first aspect, an embodiment of the present application provides a battery cell, comprising: a shell having a first wall; a pressure relief structure, the pressure relief structure being arranged on the first wall; an electrode assembly, the electrode assembly being a wound electrode assembly and being arranged in the shell, the electrode assembly comprising a flat portion and a first curved portion, along a first direction, the first curved portion being arranged on a side of the flat portion facing the first wall; wherein, a first dividing line is provided between the first curved portion and the flat portion, the distance between the first dividing line and the first wall is L, L ≥ 5 mm, and the first direction is perpendicular to the axial direction of the electrode assembly.

[0007] In the above technical solution, by setting the distance L between the first dividing line between the first curved portion located between the flat portion and the first wall and the flat portion and the first wall to be ≥5mm, and the pressure relief structure is provided on the first wall, when the electrode assembly expands and deforms, it is beneficial to weaken the effect of the part of the shell close to the first wall on the first wall, and weaken the pulling effect of other shell walls on the pressure relief structure through the first wall, which can reduce the probability of damage such as cracking of the pressure relief structure on the first wall, and improve the reliability of the battery cell.

[0008] In some embodiments, the shell also has a second wall, which is arranged opposite to the first wall along the first direction. The electrode assembly also includes a second bent portion, which is arranged on the side of the flat portion facing the second wall along the first direction. The distance between the first dividing line and the first wall is greater than or equal to the distance between the second dividing line and the second wall.

[0009] In the above technical solution, by setting the distance between the electrode assembly and the first wall to be less than or equal to the distance between the electrode assembly and the second wall, so as to reduce the risk of the pressure relief structure being pulled and cracked, the setting position requirements of the electrode assembly in the first direction are relatively low, which is conducive to improving the assembly convenience of the battery cell; at the same time, it can also better utilize the partial space adjacent to the second wall in the shell to a certain extent, so as to maintain the energy density of the battery cell.

[0010] In some embodiments, a boss is formed on the inner surface of the first wall, and the boss is disposed opposite to the electrode assembly and is suitable for supporting the electrode assembly.

[0011] In the above technical solution, a boss is formed by setting the inner surface of the first wall, and the boss is suitable for supporting the electrode assembly, which is conducive to further appropriately increasing the distance between the end of the innermost circle of the electrode assembly adjacent to the first wall in the first direction and the first wall, and is conducive to further appropriately increasing the distance between the flat portion and the first wall, so that when the electrode assembly expands and deforms, the distance between the position where the main force exerted by the flat portion on the corresponding shell wall and the first wall can be increased to a certain extent, thereby facilitating further reducing the force applied to the first wall, weakening the pulling effect of other shell walls of the shell except the first wall on the pressure relief structure through the first wall due to the expansion of the electrode assembly, and is conducive to further improving the reliability of the battery cell.

[0012] In some embodiments, a surface of the first curved portion facing the first wall is an arc surface, and a radius of the arc surface is R, where R≤L.

[0013] In the above technical solution, by setting the distance between the first dividing line and the first wall to be greater than or equal to the radius of the arc surface corresponding to the first curved portion, it is convenient to provide sufficient layout space for the first curved portion, and after the electrode assembly is wound and placed inside the shell, no large force will be generated between the first curved portion and the first wall, which may easily cause the first curved portion to wrinkle, etc., so as to maintain the performance and reliability of the electrode assembly.

[0014] In some embodiments, there are multiple electrode assemblies, the axes of the multiple electrode assemblies are arranged in parallel, and the multiple electrode assemblies are stacked along the axis and / or third direction of the electrode assembly, and the third direction is perpendicular to the axis and the first direction of the electrode assembly.

[0015] In the above technical solution, by providing multiple electrode assemblies, it is beneficial to obtain appropriate values ​​for the voltage and capacity of the battery cell, and it is beneficial to expand the range of battery cell voltage and capacity that can be achieved, thereby improving the applicability of the battery cell.

[0016] In some embodiments, the battery cell further includes an insulating member, at least a portion of which is disposed between the first wall and the electrode assembly.

[0017] In the above technical solution, by arranging an insulating member so that at least part of the insulating member is arranged between the first wall and the electrode assembly, the insulating member can separate the first wall and the electrode assembly, thereby improving the insulation performance between the first wall and the electrode assembly. At the same time, it is convenient to raise the electrode assembly through the insulating member, which is beneficial to further appropriately increase the distance between the flat portion and the first wall, so that when the electrode assembly expands and deforms, the distance between the position where the main force exerted by the flat portion on the corresponding shell wall and the first wall can be increased to a certain extent, thereby facilitating further reducing the force applied to the first wall, weakening the pulling effect of the shell walls other than the first wall on the pressure relief structure through the first wall due to the expansion of the electrode assembly, and further improving the reliability of the battery cell.

[0018] In some embodiments, at least a portion of the insulating member is disposed between the pressure relief structure and the electrode assembly and forms a discharge portion, the discharge portion comprising: a first connecting channel, the first connecting channel penetrating the insulating member along a first direction from a side of the insulating member facing the pressure relief structure; and / or, a second connecting channel, the second connecting channel penetrating the outer peripheral wall of the insulating member along a direction perpendicular to the first direction from a side of the insulating member facing the pressure relief structure.

[0019] In the above technical solution, a discharge portion is formed by arranging the portion of the insulating member disposed between the pressure relief structure and the electrode assembly. The discharge portion includes a first connecting channel and / or a second connecting channel, so that the insulating member is relatively stably disposed between the pressure relief structure and the electrode assembly. At the same time, the arrangement of the insulating member is not likely to affect the pressure relief and discharge of the battery cell, and can achieve smooth pressure relief of the battery cell.

[0020] In some embodiments, a relief groove is formed on at least a portion of a side of the insulating member facing the pressure relief structure. The relief groove is arranged opposite to the pressure relief structure and is in communication with the discharge portion.

[0021] In the above technical solution, the avoidance groove can be formed by the surface of the insulating part located between the pressure relief structure and the electrode assembly facing the pressure relief structure, which is concave in the direction away from the pressure relief structure. This is beneficial to reducing the impact of the insulating part on the pressure relief structure, and is beneficial to improving the pressure relief smoothness of the pressure relief structure to a certain extent without interference.

[0022] In some embodiments, L≤30 mm.

[0023] In the above technical solution, by setting L≤30mm, the risk of the pressure relief structure being damaged or failing due to pulling is reduced while taking into account the volume energy density of the battery cell without excessively reducing the volume energy density of the battery cell.

[0024] In some embodiments, the thickness of the first wall is t1, 0.4 mm ≤ t1 ≤ 2 mm.

[0025] In the above technical solution, by limiting the thickness of the first wall, it is possible to prevent the excessive reduction of the volume energy density of the battery cell and reduce the probability of leakage due to damage at the pressure relief structure, thereby improving the reliability of the battery cell.

[0026] In some embodiments, the width of the flat portion in the first direction is b, and 150 mm ≤ b ≤ 600 mm.

[0027] In the above technical solution, by setting 150mm≤b≤600mm, the probability of leakage caused by damage to the pressure relief structure can be reduced while improving the energy of the battery cell, thereby improving the reliability of the battery cell.

[0028] In some embodiments, the width of the flat portion in the first direction is b, and 0.0006≤t1 / b≤0.0135.

[0029] In the above technical solution, the reduction of the volume energy density of the battery cell can be avoided to a certain extent. At the same time, the pulling on the first wall can be reduced, and the probability of the weak part of the pressure relief structure being pulled and damaged can be reduced, thereby reducing the probability of leakage at the pressure relief structure and improving the reliability of the battery cell.

[0030] In some embodiments, the multi-layer electrode layers of the electrode assembly are stacked along a third direction, the shell has two third walls arranged opposite to each other along the third direction, the first wall connects the two third walls, the thickness of the first wall is t1, the thickness of the third wall is t2, t1>t2, and the third direction is perpendicular to the axial direction and the first direction of the electrode assembly respectively.

[0031] In the above technical solution, by limiting the thickness of the first wall and the third wall, the strength of the first wall can be improved, and the probability of the weak part of the pressure relief structure being pulled and damaged can be reduced, thereby reducing the probability of leakage, improving the reliability of the battery cell, and facilitating the manufacturing and molding of the shell.

[0032] In some embodiments, 0.4 mm ≤ t1 ≤ 2 mm; and / or, 0.2 mm ≤ t2 ≤ 1.5 mm; and / or, 0.08 mm 2 ≤t1×t2≤3mm 2 ; and / or, t1-t2≤1.8mm.

[0033] In the above technical solution, by reasonably setting the thickness of the first wall and the thickness of the third wall, the risk of the pressure relief structure being pulled, cracked or failing can be further reduced to a certain extent, thereby improving reliability.

[0034] In some embodiments, the pressure relief structure and the poles of the battery cells are disposed on walls on different sides of the housing.

[0035] In the above technical solution, the pole is connected to the pole ear of the electrode assembly, and there is a certain gap between the wall where the pole is located and the main body of the electrode assembly. By placing the pressure relief structure and the pole on the walls on different sides of the shell, the distance between the pressure relief structure and the main body of the electrode assembly can be appropriately shortened to a certain extent, so that the distance between the pressure relief structure and the main body of the electrode assembly is not easily restricted by the pole. When the battery cell thermally runs away, most of the emission medium in the shell can flow directly from the edge of the main body of the electrode assembly to the pressure relief structure, thereby shortening the path of the emission medium flowing to the pressure relief structure, allowing the emission medium to flow quickly to the pressure relief structure, shortening the time for the emission medium to reach the pressure relief structure, and improving the timeliness of the pressure relief of the battery cell.

[0036] In some embodiments, the shell includes a shell body and a shell cover, the shell body is open at one end in the axial direction of the electrode assembly, the shell cover is arranged at the open end of the shell body, the first wall is arranged at the end of the shell body away from the open end, and the pole is arranged on the shell cover.

[0037] In the above technical solution, by providing the first wall formed on the shell body, the structure of the shell cover can be simplified, and at the same time, the influence of the pole on the pressure relief structure is reduced, thereby facilitating timely pressure relief of the battery cell.

[0038] In some embodiments, the shell includes a shell body and a shell cover, the shell body is open at both ends in the axial direction of the electrode assembly, the shell cover is arranged at the open end of the shell body, the first wall extends to the open ends on both sides, and each shell cover is provided with a pole.

[0039] In the above technical solution, by providing the first wall formed on the shell body, the structure of the shell cover can be simplified, and the influence of the pole on the pressure relief structure can also be reduced, so as to facilitate the timely pressure relief of the battery cell.

[0040] In some embodiments, the pressure relief structure is integrally formed with the first wall.

[0041] In the above technical solution, by integrally forming the pressure relief structure and the first wall, the pressure relief structure is formed in a simple manner, which can reduce the number of components constituting the battery cell, simplify the structure of the battery cell, and reduce costs.

[0042] In some embodiments, the inner surface and / or outer surface of the first wall is provided with a groove, and the bottom wall of the groove forms a pressure relief structure.

[0043] In the above technical solution, a groove is provided on the inner surface and / or outer surface of the first wall, and a pressure relief structure is formed on the bottom wall of the groove to facilitate the processing and forming of the pressure relief structure.

[0044] In some embodiments, a score groove is formed on the first wall, and a region of the first wall corresponding to the score groove is configured as a weak portion of the pressure relief structure, and the weak portion is configured to rupture when the battery cell is depressurized.

[0045] In the above technical solution, the first wall is provided with a notched groove, and the area of ​​the first wall corresponding to the notched groove is constructed as a weak area of ​​the pressure relief structure, which facilitates the processing and forming of the pressure relief structure.

[0046] In some embodiments, the pressure relief structure is provided separately from the first wall, and the pressure relief structure is installed on the first wall.

[0047] In the above technical solution, the pressure relief structure and the first wall are constructed as separate parts, which facilitates the arrangement of the pressure relief structure on the shell. This has low production difficulty and high efficiency, and can improve the production efficiency of battery cells.

[0048] In a second aspect, an embodiment of the present application provides a battery comprising the above-mentioned battery cell.

[0049] In the above technical solution, since the battery adopts the above battery monomer, it is beneficial to improve the reliability of the battery.

[0050] In a third aspect, an embodiment of the present application provides an electrical device, comprising the above-mentioned battery, which is used to provide electrical energy.

[0051] In the above technical solution, since the electrical device adopts the above battery and the battery has good reliability, it is beneficial to improve the reliability of the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0053] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0054] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0055] FIG3 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0056] FIG4 is an exploded view of a battery cell provided in some embodiments of the present application;

[0057] FIG5 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0058] FIG6 is a schematic diagram of the shell and the pressure relief structure shown in FIG5 ;

[0059] FIG7 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0060] FIG8 is a partial cross-sectional view of the battery cell shown in FIG7;

[0061] FIG9 is a partial cross-sectional view of a battery cell housing according to some embodiments of the present application;

[0062] FIG10 is a partial cross-sectional view of a battery cell provided in some embodiments of the present application;

[0063] FIG11 is a schematic diagram of a pressure relief structure provided in some embodiments of the present application;

[0064] FIG12 is an exploded view of a battery cell provided in some embodiments of the present application;

[0065] FIG13 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0066] FIG14 is a partial cross-sectional view of the battery cell shown in FIG13;

[0067] FIG15 is an exploded view of a battery cell provided in some embodiments of the present application;

[0068] FIG16 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0069] FIG17 is a partial cross-sectional view of the battery cell shown in FIG16;

[0070] FIG18 is a schematic diagram of an electrode assembly and a first wall provided in some embodiments of the present application.

[0071] Reference numerals:

[0072] Electric device 1000, controller 300, motor 400,

[0073] Battery 200, battery cell 100, housing 101, first housing 101a, second housing 101b,

[0074] Shell 1, first wall 11, groove 11a, notched groove 11b, boss 11c, second wall 12, third wall 13, shell body 1a, shell cover 1b, pressure relief structure 2, electrode assembly 3, flat portion 3a, first bent portion 3b, second bent portion 3c, pole 4, insulating member 5, discharge portion 51, first connecting channel 51a, second connecting channel 51b. DETAILED DESCRIPTION

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the dimensions and other sizes of the various components in the embodiments of the present application shown in the drawings are for illustrative purposes only and should not constitute any limitation on the present application.

[0080] The term "plurality" used in this application refers to two or more (including two).

[0081] In this application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, or lead-acid batteries, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0082] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may be a battery module or battery pack. A battery module generally includes multiple battery cells. A battery generally includes a casing for enclosing multiple battery cells or multiple battery modules. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells. Of course, the battery may also not include a casing.

[0083] For example, a battery cell may generally include a housing, a cell assembly, and an electrolyte. The housing is used to accommodate the cell assembly and the electrolyte, and is provided with at least one positive electrode post and at least one negative electrode post. The cell assembly includes one or more electrode assemblies, which are formed by stacking or winding a positive electrode sheet, a negative electrode sheet, and a separator. The housing may be a steel shell, an aluminum shell, a plastic shell (such as a polypropylene shell), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film.

[0084] Among them, the positive electrode sheet generally includes a positive electrode sheet body and a positive electrode active material layer. The positive electrode active material layer is directly or indirectly coated on the positive electrode sheet body. The positive electrode sheet body not coated with the positive electrode active material layer serves as a positive electrode tab. Multiple positive electrode tabs are stacked together and electrically connected to the positive electrode column. For example, the multiple stacked positive electrode tabs can be directly welded to the positive electrode column to form an electrical connection; alternatively, the battery cell assembly may further include a positive electrode adapter. The multiple stacked positive electrode tabs are welded to one end of the positive electrode adapter, and the other end of the positive electrode adapter is welded to the positive electrode column to form an electrical connection between the positive electrode tab and the positive electrode column.

[0085] The negative electrode sheet can generally include a negative electrode sheet body and a negative electrode active material layer. The negative electrode active material layer is directly or indirectly coated on the negative electrode sheet body. The negative electrode sheet body not coated with the negative electrode active material layer serves as a negative electrode tab sheet. Multiple negative electrode tab sheets are stacked together and electrically connected to the negative electrode column. For example, the multiple stacked negative electrode tab sheets can be directly welded to the negative electrode column to form an electrical connection; alternatively, the battery cell assembly can further include a negative electrode adapter sheet. The multiple stacked negative electrode tab sheets are welded to one end of the negative electrode adapter sheet, and the other end of the negative electrode adapter sheet is welded to the negative electrode column to form an electrical connection between the negative electrode tab sheet and the negative electrode column. The material of the separator is not limited, for example, it can be polypropylene or polyethylene.

[0086] The pressure relief structure on the battery cell mentioned in this application is used to release gas from the battery cell when the internal pressure of the battery cell is too high (for example, due to overcharging), thereby reducing the internal pressure of the battery cell and preventing the battery cell from exploding due to excessive internal pressure, thereby improving the safety of the battery cell. For example, the pressure relief structure can be an explosion-proof valve, explosion-proof disk, etc.

[0087] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, batteries, as the power source of electric vehicles, play an irreplaceable and important role. As core components of new energy vehicles, batteries have high requirements in terms of both energy density and reliability.

[0088] In related technologies, a battery includes multiple battery cells. A battery cell generates a large amount of heat during continuous charging and discharging. Generally, a pressure relief structure is provided in the battery cell to relieve pressure when the battery cell experiences thermal runaway.

[0089] When designing a battery cell, considering the battery's energy density, the battery cell's electrode assembly occupies as much space within the casing as possible. Therefore, the distance between the electrode assembly and the casing wall where the pressure relief structure is located is relatively close to the distance between the electrode assembly and the casing wall opposite the pressure relief structure. However, when the battery cell's electrode assembly expands and deforms, the battery cell's casing also deforms, causing the casing to bulge. The pressure relief structure is usually located on the casing, which subjects the casing wall where the pressure relief structure is located to tension. When the tension reaches a certain level, it can easily cause the pressure relief structure to crack, resulting in damage and failure, and reduced battery cell reliability. Therefore, developing safer, heat-resistant battery systems has become a goal pursued by battery manufacturers and automakers.

[0090] Based on the above considerations, in order to improve the reliability of the battery cell, a battery cell is proposed, including a shell, a pressure relief structure and an electrode assembly, the shell having a first wall, the pressure relief structure being arranged on the first wall, the electrode assembly being a wound electrode assembly and being arranged in the shell, the electrode assembly including a flat portion and a first curved portion, along a first direction, the first curved portion being arranged on a side of the flat portion facing the first wall, wherein a first dividing line is provided between the first curved portion and the flat portion, the distance between the first dividing line and the first wall being L, L≥5mm, and the first direction being perpendicular to the axial direction of the electrode assembly.

[0091] In the above technical solution, by setting the distance L between the first dividing line between the first curved portion located between the flat portion and the first wall and the flat portion and the first wall to be ≥5mm, and the pressure relief structure is provided on the first wall, when the electrode assembly expands and deforms, it is beneficial to weaken the effect of the part of the shell close to the first wall on the first wall, and weaken the pulling effect of other shell walls on the pressure relief structure through the first wall, which can reduce the probability of damage such as cracking of the pressure relief structure on the first wall, and improve the reliability of the battery cell.

[0092] The present application provides an electrical device using the battery of the present disclosure as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, and the like. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, and the like. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, and the like.

[0093] For the convenience of description, the following embodiments take the electric device 1000 as a vehicle as an example, and describe in detail the structures of the electric device 1000, the battery 200 and the battery cell 100 of the present application.

[0094] Please refer to Figure 1, which is a schematic structural diagram of a vehicle in which the power-consuming device 1000 provided in some embodiments of the present application is a vehicle. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. The vehicle is provided with a battery 200, and the battery 200 can be arranged at the bottom, head or tail of the vehicle. The battery 200 can be used to power the vehicle, for example, the battery 200 can be used as an operating power source for the vehicle. The vehicle may also include a controller 300 and a motor 400, and the controller 300 is used to control the battery 200 to power the motor 400, for example, for the starting, navigation and working power requirements of the vehicle during driving. In some embodiments of the present application, the battery 200 can not only serve as the operating power source of the vehicle, but also as the driving power source of the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0095] Please refer to Figure 2, which is an exploded view of the structure of a battery 200 provided in some embodiments of the present application. The battery 200 includes a housing 101 and a plurality of battery cells 100, and the battery cells 100 are accommodated in the housing 101. The housing 101 is used to provide an assembly space for the battery cells 100, and the housing 101 can adopt a variety of structures. In some embodiments, the housing 101 can include a first housing 101a and a second housing 101b, and the first housing 101a and the second housing 101b cover each other, and the first housing 101a and the second housing 101b jointly define a housing cavity for accommodating the battery cells. The second box 101b can be a hollow structure with one end open, and the first box 101a can be a plate-like structure. The first box 101a covers the open side of the second box 101b, so that the first box 101a and the second box 101b together define a storage cavity; alternatively, the first box 101a and the second box 101b can both be hollow structures with one end open (for example, as shown in FIG. 2 ), with the open side of the first box 101a covering the open side of the second box 101b. Of course, the box 101 formed by the first box 101a and the second box 101b can be of various shapes, such as a cylinder or a rectangular parallelepiped.

[0096] In the battery 200, multiple battery cells 100 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 100. Multiple battery cells 100 can be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 100 can be housed within the housing 101. Alternatively, the battery 200 can be constructed by first connecting multiple battery cells 100 in series, in parallel, or in a hybrid connection to form a battery module. The multiple battery modules are then connected in series, in parallel, or in a hybrid connection to form a single unit, which is then housed within the housing 101. The battery 200 may also include other structures. For example, the battery 200 may also include a busbar to electrically connect the multiple battery cells 100.

[0097] In some embodiments, the box 101 may serve as part of a chassis structure of a vehicle. For example, the box 101 may serve as at least a portion of a floor of the vehicle, or the box 101 may serve as at least a portion of a cross member and a longitudinal member of the vehicle.

[0098] Please refer to Figures 3-6. Figure 3 is a schematic diagram of the structure of a battery cell 100 provided in some embodiments of the present application. Figure 4 is a schematic diagram of the structure of a battery cell 100 provided in some embodiments of the present application. Figure 5 is a schematic diagram of the structure of a battery cell provided in some embodiments of the present application. Figure 6 is a schematic diagram of the shell and pressure relief structure shown in Figure 5. The battery cell 100 is a rectangular parallelepiped, with the height direction of the battery cell 100 being a first direction X, the length direction of the battery cell 100 being a second direction Y, and the thickness direction of the battery cell 100 being a third direction Z. The first direction X, the second direction Y, and the third direction Z are mutually perpendicular; however, this is not limiting. In other embodiments of the present application, the battery cell 100 may also be a polygonal prism, a flat body, or other shapes.

[0099] Please refer to Figures 3 to 5. In an embodiment of the present application, the battery cell 100 includes a shell 1 and a pressure relief structure 2. The shell 1 has a first wall 11. The pressure relief structure 2 is provided on the first wall 11. The pressure relief structure 2 is configured to release the pressure inside the battery cell 100.

[0100] The battery cell 100 also includes an electrode assembly 3, which is arranged in the shell 1, and the electrode assembly 3 is a wound electrode assembly. The electrode assembly 3 includes a flat portion 3a and a first curved portion 3b. Along the first direction, the first curved portion 3b is arranged on the side of the flat portion 3a facing the first wall 11. The first direction is perpendicular to the axial direction of the electrode assembly 3. The axial direction of the electrode assembly 3 can be understood as the extension direction of the winding center axis of the electrode assembly 3; exemplarily, the axial direction of the electrode assembly 3 is the second direction Y in Figure 4.

[0101] It can be seen that the first wall 11 can be a shell wall of the shell 1 in the first direction; in the first direction, the first curved portion 3 b is provided between the flat portion 3 a and the first wall 11 .

[0102] It will be appreciated that in the embodiment of the present application, both sides of the flat portion 3a in the third direction Z are planes, and the side of the first curved portion 3b facing away from the flat portion 3a is a curved surface (e.g., an arc surface). In this case, the position of the first dividing line Ω1 between the first curved portion 3b and the flat portion 3a can be determined by whether the curvature of the surface of the portion of the electrode assembly 3 adjacent to the first wall 11 changes. The portion with a changed surface curvature is the first curved portion 3b, while the portion with unchanged surface curvature is the flat portion 3a. For example, the width of the flat portion 3a in the third direction is constant, while the width of the first curved portion 3b in the third direction is variable. In this case, the position of the first dividing line Ω1 between the first curved portion 3b and the flat portion 3a can be determined by whether the width of the electrode assembly 3 in the third direction changes. The third direction is perpendicular to both the axial direction of the electrode assembly 3 and the first direction.

[0103] It is understood that one or more electrode assemblies 3 may be provided within the housing 1, each electrode assembly 3 including multiple anode electrode sheets and multiple cathode electrode sheets stacked along a third direction Z. When multiple electrode assemblies 3 are provided within the housing 1, the axial directions of the multiple electrode assemblies 3 are arranged parallel to each other, and the multiple electrode assemblies 3 may be arranged sequentially along the third direction and / or the axial direction of the electrode assembly 3. Exemplarily, the electrode assembly 3 is a wound structure, i.e., the multiple electrode sheets of the electrode assembly 3 are stacked and wound to form a flat region 30. In the flat region 30, a portion of the anode electrode sheet, i.e., the anode electrode sheet layer, and a portion of the cathode electrode sheet, i.e., the cathode electrode sheet layer 31, are stacked. For example, after winding, both the cathode electrode sheet layer and the anode electrode sheet layer can be penetrated by an axis extending along the third direction. In this case, the expansion deformation of the electrode assembly 3 is particularly significant in the third direction, which is perpendicular to the first direction and the axial direction of the electrode assembly 3. The flat region 30 corresponds to the flat portion 3a.

[0104] Obviously, when the electrode assembly 3 expands, most of the expansion of the electrode assembly 3 will act on the shell wall of the shell 1 in the third direction, and the first wall 11 is affected less by the expansion of the electrode assembly 3 than other shell walls. Therefore, the pressure relief structure 2 is arranged on the first wall 11, which is beneficial to reducing the risk of blocking or damaging the pressure relief structure 2 due to the expansion of the electrode assembly 3.

[0105] Among them, there is a first dividing line Ω1 between the first curved portion 3b and the flat portion 3a, and the distance between the first dividing line Ω1 and the first wall 11 is L, L ≥ 5mm, and the position of the first dividing line Ω1 relative to the first wall 11 is closely related to the position of the flat portion 3a relative to the first wall 11 in the first direction. The above arrangement can make the flat portion 3a have a larger distance from the first wall 11 in the first direction. When the electrode assembly 3 expands and deforms, the expansion deformation of the electrode assembly 3 is particularly obvious in the third direction. The electrode assembly 3 applies a force to the shell wall (for example, the third shell wall 13) of the shell 1 in the third direction, that is, the flat portion 3a contacts the above shell wall before the first curved portion 3b to apply the force, or the first curved portion The width of 3b in the third direction is smaller than that of the flat portion 3a, so that the force exerted by the electrode assembly 3 on the shell wall mainly comes from the force exerted by the flat portion 3a on the shell wall, which facilitates increasing the distance between the position where the main force exerted by the flat portion 3a on the above-mentioned shell wall and the first wall 11, thereby helping to reduce the force exerted by other shell walls on the first wall 11, so that the first wall 11 is basically not subjected to force or the force exerted on the first wall 11 is relatively small, thereby weakening the pulling effect of other shell walls (such as the third shell wall 13) of the shell 1 except the first wall 11 through the first wall 11 due to the expansion of the electrode assembly 3, thereby reducing the probability of damage to the pressure relief structure 2 such as cracking on the first wall 11, and improving the reliability of the battery cell 100.

[0106] In addition, the above-mentioned setting of the embodiment of the present application can reduce the risk of the pressure relief structure 2 being pulled and damaged, and can also reduce the probability of leakage due to failure of the pressure relief structure 2 to a certain extent, further improving the reliability of the battery cell 100.

[0107] Exemplarily, the height direction of the battery cell 100 is the first direction X, the length direction of the battery cell 100 is the second direction Y, and the thickness direction of the battery cell 100 is the third direction Z. In the first direction X, the distance L between the first dividing line Ω1 and the first wall 11 is ≥5 mm. Taking the first direction X as the up-down direction as an example, the first wall 11 is the bottom wall of the shell 1. The relative position between the first dividing line Ω1 and the first wall 11 is limited, which is conducive to reducing the force on the lower part of the shell 1 due to the expansion and deformation of the electrode assembly 3, thereby reducing the pulling effect on the pressure relief structure 2 on the bottom wall of the shell 1, and reducing the risk of the pressure relief structure 2 being pulled and cracked; in addition, the pressure relief structure 2 is arranged on the bottom wall of the shell 1, so that the battery cell 100 realizes a bottom spray design, which is conducive to improving the heat spread of the battery 200. For example, the battery 200 is generally placed at the bottom of the electrical device, with electrical components or personnel above it. When the battery 200 has thermal runaway, the battery cell 100 can exhaust and release pressure downward, thereby reducing the fire in the area above the battery 200, especially when the number of battery cells 100 is large, that is, reducing the loss of electrical components and reducing personal injury. The use of this structure can reduce the impact of the battery 200 on the electrical device under thermal runaway and improve the safety of the battery 200.

[0108] In the above technical solution, by setting the distance between the first curved portion 3b located between the flat portion 3a and the first wall 11 and the first dividing line Ω1 between the flat portion 3a and the first wall 11 to L≥5mm, and the pressure relief structure 2 is provided on the first wall 11, when the electrode assembly 3 expands and deforms, it is beneficial to weaken the effect of the part of the shell 1 close to the first wall 11 on the first wall 11, and weaken the pulling effect of other shell walls of the shell 1 on the pressure relief structure 2 through the first wall 11, which can reduce the probability of damage such as cracking of the pressure relief structure 2 on the first wall 11, thereby improving the reliability of the battery cell 100.

[0109] It can be understood that the distance L can be greater than or equal to the maximum dimension of the first curved portion 3b in the first direction; for example, the surface of the first curved portion 3b facing away from the flat portion 3a is an arc surface with a radius of R, L≥R.

[0110] Referring to Figures 7, 13, and 16, in some embodiments, the housing 11 further includes a second wall 12, which is disposed opposite the first wall 11 along the first direction. The electrode assembly 3 further includes a second curved portion 3c, which is disposed on the side of the flat portion 3a facing the second wall 12 along the first direction. The first curved portion 3b and the second curved portion 3c can then be disposed opposite each other along the first direction and on either side of the flat portion 3a in the first direction. A second boundary surface Ω2 is defined between the second curved portion 3c and the flat portion 3a, and the distance L between the first boundary line Ω1 and the first wall 11 is greater than or equal to the distance L' between the second boundary surface Ω2 and the second wall 12. It can be seen that in the first direction, between the first wall 11 and the second wall 12, the electrode assembly 3 can be centered relative to the first wall 11 and the second wall 12, or positioned closer to the second wall 12 relative to the first wall 11.

[0111] In the above technical solution, by setting the distance between the first dividing line Ω1 and the first wall 11 to be greater than or equal to the distance between the second dividing line Ω2 and the second wall 12, so as to reduce the risk of the pressure relief structure 2 being pulled and cracked, the setting position requirements of the electrode assembly 3 in the first direction are relatively low, which is beneficial to improving the assembly convenience of the battery cell 100; at the same time, it can also better utilize the partial space adjacent to the second wall 12 in the shell 1 to a certain extent, so as to maintain the energy density of the battery cell 100.

[0112] It can be understood that in the embodiment of the present application, the two side surfaces of the flat portion 3a in the third direction Z are respectively planes, and the surface of the second curved portion 3c facing away from the flat portion 3a is a curved surface (such as an arc surface, etc.). At this time, the position of the second dividing line Ω2 between the second curved portion 3c and the flat portion 3a can be determined by whether the curvature of the surface of the portion of the electrode assembly 3 adjacent to the first wall 12 changes. The second curved portion 3c has a changed surface curvature, and the flat portion 3a has a unchanged surface curvature. For example, the width of the flat portion 3a in the third direction is a constant value, and the width of the second curved portion 3c in the third direction is a variable value. At this time, the position of the second dividing line Ω2 between the second curved portion 3c and the flat portion 3a can be determined by whether the width of the electrode assembly 3 in the third direction changes.

[0113] In addition, the distance L' may be greater than or equal to the maximum dimension of the second curved portion 3c in the first direction; for example, the surface of the second curved portion 3c facing away from the flat portion 3a is an arc surface with a radius of R, and L'≥R'.

[0114] Referring to Figure 10 , in some embodiments, a boss 11c is formed on the inner surface of the first wall 11. The boss 11c may be formed by a portion of the inner surface of the first wall 11 protruding toward the interior of the battery cell 100. The boss 11c is disposed opposite the electrode assembly 3 along a first direction, and the boss 11c is adapted to support the electrode assembly 3. For example, the boss 11c is disposed opposite the first curved portion 3b along the first direction, and the boss 11c is adapted to support the first curved portion 3b.

[0115] In the above technical solution, a boss 11c is formed on the inner surface of the first wall 11, and the boss 11c is suitable for supporting the electrode assembly 3, which is conducive to further appropriately increasing the distance between the end of the innermost circle of the electrode assembly 3 adjacent to the first wall 11 in the first direction and the first wall 11, and is conducive to further appropriately increasing the distance between the flat portion 3a and the first wall 11, so that when the electrode assembly 3 expands and deforms, the distance between the position where the main force exerted by the flat portion 3a on the corresponding shell wall (for example, the third shell wall 13) and the first wall 11 can be increased to a certain extent, thereby facilitating further reducing the force applied to the first wall 11, weakening the pulling effect of the shell walls other than the first wall 11 of the shell 1 on the pressure relief structure 2 through the first wall 11 due to the expansion of the electrode assembly 3, and is conducive to further improving the reliability of the battery cell 100.

[0116] It can be understood that the boss 11 c can directly support the electrode assembly 2 , or the boss 11 c can indirectly support the electrode assembly 3 .

[0117] Referring to FIG. 8 , in some embodiments, a surface of the first curved portion 3 b facing the first wall 11 is an arc surface, and a radius of the arc surface is R, where R≤L.

[0118] In the above scheme, by setting the distance between the first dividing line Ω1 and the first wall 11 to be greater than or equal to the radius R of the arc surface corresponding to the first bend 3b, it is convenient to provide sufficient layout space for the first bend 3b, and after the electrode assembly 3 is wound and placed inside the shell 1, no large force will be generated between the first bend 3b and the first wall 11, which may easily cause the first bend 3b to wrinkle, etc., so as to maintain the performance and reliability of the electrode assembly 3.

[0119] Please refer to Figures 15 to 17. In some embodiments, there are multiple electrode assemblies 3, and the axes of the multiple electrode assemblies 3 are arranged in parallel. The multiple electrode assemblies 3 are stacked along the axis and / or the third direction of the electrode assembly 3, and the third direction is perpendicular to the axis and the first direction of the electrode assembly 3, respectively.

[0120] In the above technical solution, by providing multiple electrode assemblies 3, it is beneficial to obtain appropriate values ​​for the voltage and capacity of the battery cell 100, and it is beneficial to expand the range of voltage and capacity that can be achieved by the battery cell 100, thereby improving the applicability of the battery cell 100.

[0121] For example, as shown in Figures 15 to 17 , there are two electrode assemblies 3 , which are sequentially arranged along the third direction. Of course, there can also be three or more electrode assemblies 3 .

[0122] It can be understood that, when there are multiple electrode assemblies 3 , each electrode assembly 3 corresponds to a first dividing line Ω1 , and the distances between the multiple first dividing lines Ω1 and the first wall 11 may be equal or different.

[0123] Referring to FIG. 13 and FIG. 14 , in some embodiments, the battery cell 100 further includes an insulating member 5 , at least a portion of which is disposed between the first wall 11 and the electrode assembly 3 .

[0124] In the above technical solution, by arranging the insulating member 5 so that at least part of the insulating member 5 is arranged between the first wall 11 and the electrode assembly 3, the insulating member 5 can separate the first wall 11 and the electrode assembly 3, thereby improving the insulation performance between the first wall 11 and the electrode assembly 3. At the same time, it is convenient to raise the electrode assembly 3 through the insulating member 5, which is beneficial to further appropriately increase the distance between the flat portion 3a and the first wall 11, so that when the electrode assembly 3 expands and deforms, the distance between the position where the main force exerted by the flat portion 3a on the corresponding shell wall (for example, the third shell wall 13) and the first wall 11 can be increased to a certain extent, thereby facilitating further reducing the force applied to the first wall 11, weakening the pulling effect of the shell walls other than the first wall 11 of the shell 1 on the pressure relief structure 2 through the first wall 11 due to the expansion of the electrode assembly 3, and further improving the reliability of the battery cell 100.

[0125] For example, the insulating member 5 is configured as a flat plate structure.

[0126] Please refer to Figures 13 and 14. In some embodiments, the above-mentioned at least portion of the insulating member 5 is arranged between the pressure relief structure 2 and the electrode assembly 3, and the above-mentioned at least portion of the insulating member 5 is formed with a discharge portion 51, and the discharge portion 51 includes a first connecting channel 51a and / or a second connecting channel 51b. The first connecting channel 51a penetrates the insulating member 5 along the first direction from the side of the insulating member 5 facing the pressure relief structure 2, so that the first connecting channel 51a connects the two sides of the insulating member 5 in the first direction, and the second connecting channel 51b penetrates the outer peripheral wall of the insulating member 5 along the direction perpendicular to the first direction from the side of the insulating member 5 facing the pressure relief structure 2, so that the second connecting channel 51b can also connect the two sides of the insulating member 5 in the first direction.

[0127] It is understood that the second communication channel 51a can penetrate the outer peripheral wall of the insulating member 5 in any direction perpendicular to the first direction. It can be seen that the discharge portion 51 can be configured to allow the discharged medium inside the battery cell 100 to move from the side of the insulating member 5 facing away from the pressure relief structure 2 to the side of the insulating member 5 facing the pressure relief structure 2.

[0128] In the above technical solution, a discharge portion 51 is formed by arranging the portion of the insulating part 5 between the pressure relief structure 2 and the electrode assembly 3. The discharge portion 51 includes a first connecting channel 51a and / or a second connecting channel 51b, so that the insulating part 5 is relatively stably arranged between the pressure relief structure 2 and the electrode assembly 3. At the same time, the arrangement of the insulating part 5 is not likely to affect the pressure relief and discharge of the battery cell 100, and can achieve smooth pressure relief of the battery cell 100.

[0129] Optionally, when the discharge portion 51 includes a first connecting channel 51a, the first connecting channel 51a can be arranged opposite to the pressure relief structure 2 along a first direction so as to shorten the discharge path of the battery cell 100; when the discharge portion 51 includes a second connecting channel 51b, at least a portion of the second connecting channel 51b is staggered with the pressure relief structure 2 in a direction perpendicular to the first direction.

[0130] Please refer to Figure 14. In some embodiments, a side avoidance groove 5a is formed on the side of the insulating member 5 facing the pressure relief structure 2. The side avoidance groove 5a is arranged opposite to the pressure relief structure 2 and is connected to the discharge portion 51.

[0131] In the above scheme, the avoidance groove 5a can be formed by the surface of the insulating part 5 located between the pressure relief structure 2 and the electrode assembly 3 facing the pressure relief structure 2, which is concave in the direction away from the pressure relief structure 2. This is beneficial to reducing the impact of the insulating part 5 on the pressure relief structure 2, and is beneficial to improving the pressure relief smoothness of the pressure relief structure 2 to a certain extent without interference.

[0132] In some embodiments, L≤30 mm.

[0133] In the above technical solution, by setting L≤30mm, the risk of the pressure relief structure 2 being damaged or failing due to pulling is reduced while taking into account the volume energy density of the battery cell 100 without excessively reducing the volume energy density of the battery cell 100.

[0134] Illustratively, L can be 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, 23 mm, 25 mm, 28 mm, or 30 mm, etc.

[0135] Please refer to FIG8-FIG10, FIG14 and FIG17. In some embodiments, the thickness of the first wall 11 is t1, and 0.4 mm≤t1≤2 mm.

[0136] The thickness of the first wall 11 is t1, where the thickness of the first wall 11 is the distance between the inner and outer sides of the first wall 11. For example, the first wall 11 can be formed into a flat plate structure, in which case the thickness of the first wall 11 is the same at different locations; alternatively, the first wall 11 can include a main body region and local regions, wherein the local regions can be provided with grooves, protrusions, or other special structures such as holes, and the local regions can be located around the main body region, in the middle of the main body region, or in a dispersed arrangement. In this case, the thickness of the first wall 11 is the thickness of the main body region.

[0137] If the thickness of the first wall 11 is too large, the size of the shell 1 will occupy too much of the overall space of the battery cell 100, and the space occupied by the corresponding electrode assembly 3 will be reduced, which will lead to a decrease in the volume energy density of the battery cell 100. If the thickness of the first wall 11 is too small, the first wall 11 is too thin, and when the electrode assembly 3 expands, the first wall 11 is easily pulled and deformed, which will easily cause the weak part of the pressure relief structure 2 to be pulled and damaged, causing the pressure relief structure 2 to fail or leak, etc.

[0138] For example, t1 can be any point value among 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, or a range value between any two of them.

[0139] In the above technical solution, by limiting the thickness of the first wall 11 , it is possible to prevent the excessive reduction of the volume energy density of the battery cell 100 and reduce the probability of leakage due to damage at the pressure relief structure 2 , thereby improving the reliability of the battery cell 100 .

[0140] Referring to FIG. 7 , FIG. 13 and FIG. 16 , in some embodiments, the width of the flat portion 3 a in the first direction is b, and 150 mm ≤ b ≤ 600 mm.

[0141] If b is too small, the size of the flat portion 3a in the first direction is small, and the electrode assembly 3 as a whole is small in the first direction, which will relatively cause a decrease in the energy of the battery cell 100. If b is too large, the size of the flat portion 3a in the first direction is large, and the size of the electrode assembly 3 as a whole is large in the first direction, and the expansion of the electrode assembly 3 is large, thereby increasing the pulling force on the surface where the pressure relief structure 2 is located, which can easily cause the weak parts of the pressure relief structure 2 to be pulled and damaged, causing leakage at the pressure relief structure 2.

[0142] Therefore, b is limited to between 150mm and 600mm. b can be any point value among 150mm, 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm, or a range value between any two of them.

[0143] Through the above definition, the probability of leakage caused by damage to the pressure relief structure 2 can be reduced on the basis of improving the energy of the battery cell 100, thereby improving the reliability of the battery cell 100.

[0144] Furthermore, 220mm≤b≤530mm.

[0145] b can be any point value of 220mm, 260mm, 280mm, 300mm, 320mm, 340mm, 360mm, 380mm, 400mm, 420mm, 440mm, 460mm, 480mm, 500mm, 520mm, 530mm or a range value between any two of them.

[0146] Within the above range, the energy of the battery cell 100 can be further optimized, while the probability of leakage caused by damage to the pressure relief structure 2 can be reduced, thereby improving the reliability of the battery cell 100.

[0147] In some embodiments, 0.0006≤t1 / b≤0.0135. When t1 / b is too small, the thickness of the first wall 11 is too small, the strength of the first wall 11 is low, and the first wall 11 is easily pulled and deformed, which in turn causes the pressure relief structure 2 to be easily pulled and damaged, resulting in leakage. Alternatively, the width of the flat portion 3a in the first direction is too large, and the electrode assembly 3 expands significantly, which increases the pulling on the first wall 11, easily causing the weak portion of the pressure relief structure 2 to be pulled and damaged, causing the pressure relief structure 2 to leak. When t1 / b is too large, the thickness of the first wall 11 is too large, causing the size of the housing 1 in the first direction to occupy too much of the overall size and volume of the battery cell 100. Alternatively, the width of the flat portion 3a in the first direction is too small, corresponding to the undersized size of the electrode assembly 3, resulting in a reduction in the volume energy density of the battery cell 100.

[0148] To this end, t1 / b is limited to between 0.0006 and 0.0135. t1 / b can be any one of 0.0006, 0.001, 0.002, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.011, 0.0115, 0.012, 0.0125, 0.013, 0.0135, or a range between any two of them.

[0149] Please refer to Figures 8-10, 14 and 17. In some embodiments, the multi-layer electrode layers of the electrode assembly 3 are stacked along the third direction, and the shell 1 has two third walls 13 arranged opposite to each other along the third direction. The first wall 11 connects the two third walls 13, the thickness of the first wall 11 is t1, and the thickness of the third wall 13 is t2, t1>t2, and the third direction is perpendicular to the axial direction and the first direction of the electrode assembly respectively.

[0150] The thickness of the third wall 13 is t2, where the thickness of the third wall 13 is the distance between the inner and outer sides of the third wall 13, or the thickness of the third wall 13 in the third direction. For example, the third wall 13 can be formed into a flat plate structure, in which case the thickness of the third wall 13 is the same at different locations. Alternatively, the third wall 13 can include a main body region and local regions. The local regions can be provided with grooves, protrusions, or other special structures such as holes. The local regions can be located around the main body region, in the middle of the main body region, or in a dispersed arrangement. In this case, the thickness of the third wall 13 is the thickness of the main body region.

[0151] Here, t1>t2, that is, the thickness of the first wall 11 is greater than the thickness of the third wall 13. Since the pressure relief structure 2 is arranged on the first wall 11, by relatively increasing the thickness of the first wall 11, on the one hand, it is beneficial to improve the strength of the first wall 11, reduce the risk of damage to the pressure relief structure 2, and thus reduce the probability of leakage of the pressure relief structure 2; on the other hand, the shell 1 can be stamped by a mold during manufacturing. The thickness of the first wall 11 is greater than the thickness of the third wall 13. The shell 1 can be manufactured by stamping a plate with the same thickness as the first wall 11, which reduces the manufacturing difficulty of the shell 1.

[0152] In the technical solution of the embodiment of the present application, by limiting the thickness of the first wall 11 and the third wall 13, the strength of the first wall 11 can be improved, and the probability of the weak part of the pressure relief structure 2 being pulled and damaged can be reduced, thereby reducing the probability of leakage, improving the reliability of the battery cell 100, and facilitating the manufacturing and molding of the shell 1.

[0153] In some embodiments, the battery cell 100 satisfies at least one of the following conditions: 1. 0.4 mm ≤ t1 ≤ 2 mm; 2. 0.2 mm ≤ t2 ≤ 1.5 mm; 3. 0.08 mm 2 ≤t1×t2≤3mm 2 ; 4. t1-t2≤1.8mm.

[0154] For 0.2mm≤t2≤1.5mm, if the thickness of the third wall 13 is too large, the size of the shell 1 occupies too much of the overall volume of the battery cell 100, thereby reducing the space occupied by the electrode assembly 3 in the third direction, which will lead to a decrease in the volume energy density of the battery cell 100. If the thickness of the third wall 13 is too small, the third wall 13 is too thin, and the deformation of the third wall 13 is likely to be too large when the electrode assembly 3 expands, so the greater the pulling on the first wall 11, the more likely it is that the pressure relief structure 2 is pulled and damaged, causing leakage at the pressure relief structure 2.

[0155] Therefore, t2 can be any point value among 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, or a range value between any two of them.

[0156] By limiting the thickness of the third wall 13, it is possible to prevent the volume energy density of the battery cell 100 from being excessively reduced, and to improve the structural strength of the third wall 13, thereby reducing the deformation of the third wall 13, thereby reducing the pulling on the first wall 11, and reducing the probability of the pressure relief structure 2 being pulled and damaged and leaking, thereby improving the reliability of the battery cell 100.

[0157] Furthermore, 0.3mm≤t2≤1.2mm. t2 can be any point value among 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, and 1.2mm, or a range of values ​​between any two of them. Within the above range, the excessive reduction in the volumetric energy density of the battery cell 100 can be further prevented, while also improving the structural strength of the third wall 13 and reducing the deformation of the third wall 13. This, in turn, reduces the pulling on the first wall 11, reduces the probability of leakage caused by damage to the pressure relief structure 2, and improves the reliability of the battery cell 100.

[0158] For 0.4mm≤t1≤2mm, if the thickness of the first wall 11 is too large, the size of the shell 1 in the first direction occupies too much of the overall space of the battery cell 100, and the space occupied by the corresponding electrode assembly 3 in the first direction is reduced, which will lead to a decrease in the volume energy density of the battery cell 100. If the thickness of the first wall 11 is too small, the first wall 11 is too thin, and when the electrode assembly 3 expands, the third wall 13 deforms and pulls the first wall 11, and the first wall 11 is easily pulled and deformed, which can easily cause the weak area on the pressure relief structure 2 to be pulled and damaged, causing leakage at the pressure relief structure 2.

[0159] Therefore, t1 can be any point value among 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, or a range value between any two of them.

[0160] By limiting the thickness of the first wall 11 , it is possible to prevent the volume energy density of the battery cell 100 from being excessively reduced, and to reduce the probability of leakage due to damage at the pressure relief structure 2 , thereby improving the reliability of the battery cell 100 .

[0161] Furthermore, 0.5mm≤t1≤1.8mm. t1 can be any value among 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, and 1.8mm, or a range of values ​​therebetween. A thickness of the first wall 11 within the aforementioned range can further prevent an excessive reduction in the volumetric energy density of the battery cell 100, reduce the probability of leakage due to damage to the pressure relief structure 2, and thereby improve the reliability of the battery cell 100.

[0162] For 0.08mm 2 ≤t1×t2≤3mm 2 When t1×t2 is too small, t2 is too small, the structural strength of the third wall 13 is small, and the deformation of the third wall 13 is likely to be too large when the electrode assembly 3 expands, thereby increasing the pulling on the surface where the pressure relief structure 2 is located, which is likely to cause the weak parts of the pressure relief structure 2 to be pulled and damaged, causing leakage at the pressure relief structure 2; or t1 is too small, that is, the thickness of the first wall 11 is too small, and the structural strength of the first wall 11 is small. When the electrode assembly 3 expands, the first wall 11 is easily pulled and deformed, and then the weak parts of the pressure relief structure 2 are easily pulled and damaged, causing leakage at the pressure relief structure 2, etc.

[0163] When t1×t2 is too large, t2 is too large and the third wall 13 occupies too much space in the third direction, or when t1 is too large and the first wall 11 occupies too much space in the first direction, the arrangement space of the electrode assembly 3 in the third direction or the first direction is reduced, thereby reducing the volume energy density of the battery cell 100. Therefore, t1×t2 is limited to 0.08mm. 2 -3mm 2 Between, t1×t2 can be 0.08mm 2 , 1mm 2 , 1.2mm 2 , 1.4mm 2 , 1.6mm2 , 1.8mm 2 , 2mm 2 , 2.2mm 2 , 2.4mm 2 , 2.6mm 2 , 2.8mm 2 , 3mm 2 Any point value or any range of values ​​between them.

[0164] For t1-t2≤1.8mm, if t1-t2 is too large, it will be detrimental to the manufacturing and forming of the shell 1. If t1-t2 is too large, t1 will cause the first wall 11 to occupy too much space in the first direction, and the electrode assembly 3 will occupy less space in the first direction, affecting the volume energy density of the battery cell 100. Alternatively, if t2 is too small, the thickness of the third wall 13 will be too small, and the third wall 13 will have low structural strength and be easily deformed, which will increase the pulling on the surface where the pressure relief structure 2 is located, easily causing the weak parts of the pressure relief structure 2 to be pulled and damaged, causing leakage at the pressure relief structure 2. Through the above definition, the manufacturing and forming of the shell 1 can be facilitated on the basis of optimizing the volume energy density of the battery cell 100 and reducing the probability of leakage of the pressure relief structure 2.

[0165] Optionally, the third wall 13 is the wall with the largest area in the shell 1, and the third wall 13 can be understood as the "large surface" of the shell 1. It can be seen that the first wall 11 is a narrow shell wall connected between the two third walls 13. After the electrode assembly 3 is installed in the shell 1, the third wall 12 is opposite the flat portion 3a of the electrode assembly 3. When the internal pressure of the shell 1 reaches a certain value, the pressure relief structure 2 is released. When the electrode assembly 3 expands, the electrode assembly 3 presses against the third wall 13 and supports the shell 1 in the third direction, causing the shell 1 to deform. The third wall 13 is the main stress-bearing surface and deforms significantly. The force on the first wall 11 is less than that on the third wall 13. Therefore, by arranging the pressure relief structure 2 on the first wall 11, the pressure relief structure 2 is arranged on the smaller stress-bearing surface of the shell 1. Compared with arranging the pressure relief structure 2 on the third wall 13, the force on the pressure relief structure 2 can be reduced, thereby further reducing the risk of the pressure relief structure 2 being damaged or failing due to pulling.

[0166] Obviously, by setting the pressure relief structure 2 on the first wall 11, the first wall 11 is not the wall with the largest area of ​​the shell 1, and the pressure relief structure 2 can be set on the smaller stress surface of the shell 1. Compared with setting the pressure relief structure 2 on the third wall 13, when the electrode assembly 3 expands and deforms, the force on the pressure relief structure 2 can be reduced, which is conducive to further reducing the risk of the pressure relief structure 2 being pulled, damaged or failed.

[0167] 4 , 5 and 10 , in some embodiments, the pressure relief structure 2 and the pole 4 of the battery cell 100 are disposed on walls on different sides of the housing 1 , that is, the pole 4 is disposed on walls of the housing 1 other than the first wall 11 .

[0168] In the above technical solution, the terminal post 4 is connected to the tab of the electrode assembly 3, and a certain gap exists between the wall where the terminal post 4 is located and the main body of the electrode assembly 3. By placing the pressure relief structure 2 and the terminal post 4 on different sides of the wall of the housing 1, the distance between the pressure relief structure 2 and the main body of the electrode assembly 3 can be appropriately shortened to a certain extent, making the distance between the pressure relief structure 2 and the main body of the electrode assembly 3 less restricted by the terminal post 4. In the event of thermal runaway of the battery cell 100, most of the exhaust medium in the housing 1 can flow directly from the edge of the main body of the electrode assembly 3 to the pressure relief structure 2, thereby shortening the path for the exhaust medium to flow to the pressure relief structure 2, allowing the exhaust medium to flow quickly to the pressure relief structure 2, shortening the time it takes for the exhaust medium to reach the pressure relief structure 2, and improving the timeliness of the pressure relief of the battery cell 100. The tab includes multiple tab sheets 34.

[0169] Please refer to Figures 4, 5 and 10. In some embodiments, the shell 1 includes a shell body 1a and a shell cover 1b. The shell body 1a is open at at least one of the two ends in the axial direction of the electrode assembly 3. The shell cover 1b is arranged at the open end of the shell body 1a, and the first wall 11 is formed on the shell body 1a.

[0170] Exemplarily, the shell body 1a can be a hollow structure with an opening formed at one end, or the shell body 1a can be a hollow structure with openings formed at two opposite ends. The shell body 1a can be of various shapes, such as a prismatic shape. The shell cover 1b is a component that closes the opening of the shell body 1a to isolate the internal environment of the battery cell 100 from the external environment. The shell cover 1b and the shell body 1a together define a mounting cavity for accommodating the electrode assembly 3, electrolyte, and other components. The shape of the shell cover 1b can be compatible with the shape of the shell body 1a. For example, if the shell body 1a is a rectangular parallelepiped structure, the shell cover 1b can be a rectangular plate structure that is compatible with the shell body 1a. For another example, if the shell body 1a is a cylindrical structure, the shell cover 1b can be a circular plate structure that is compatible with the shell body 1a. The material of the shell cover 1b can also be various, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the shell cover 1b and the shell body 1a can be the same or different.

[0171] In an embodiment where the housing 1a is open at one end, as shown in FIG4 , one housing cover 1b may be provided. In an embodiment where the housing 1a is open at two opposite ends, as shown in FIG5 , FIG6 , and FIG10 , two housing covers 1b may be provided. The two housing covers 1b respectively close the two openings of the housing 1a , and the two housing covers 1b and the housing 1a together define a mounting cavity.

[0172] The shell body 1a has a first wall 11, and the pressure relief structure 2 can be integrally formed with the first wall 11 or separately set from the first wall 11. By setting the pressure relief structure 2 on the shell body 1a, the structure of the shell cover 1b can be simplified, and at the same time, it is convenient to shorten the distance between the pressure relief structure 2 and the main body of the electrode assembly 3, thereby shortening the path of the discharge medium flowing to the pressure relief structure 2 during pressure relief, shortening the time for the discharge medium to reach the pressure relief structure 2, and improving the timeliness of the pressure relief of the battery cell 100, which is conducive to further improving the reliability of the battery cell 100.

[0173] It can be seen that by setting the first wall 11 formed on the shell body 1a, the structure of the shell cover 1b can be simplified, and at the same time, it is convenient to shorten the distance between the pressure relief structure 2 and the main body of the electrode assembly 3, thereby shortening the path of the discharge medium flowing to the pressure relief structure 2 during pressure relief, shortening the time for the discharge medium to reach the pressure relief structure 2, and improving the timeliness of pressure relief of the battery cell 100.

[0174] In an embodiment where the housing 1a is open at one end, the first wall 11 is disposed at the end of the housing 1a away from the open end. The first wall 11 and the housing cover 1b are disposed opposite each other along a first direction, and the pole 4 is disposed on the housing cover 1b. In an embodiment where the housing 1a is open at both opposing ends, the first wall 11 extends to both open ends, and each housing cover 1b is provided with a pole 4.

[0175] In the above solution, by reasonably arranging the relative layout of the shell body 1a, the shell cover 1b and the pole 4, it is beneficial to improve the processing convenience and assembly convenience of the shell body 1a and the shell cover 1b, and it is also beneficial to improve the assembly convenience of the pole 4 and the housing 1.

[0176] Please refer to Figures 9 and 11. In some embodiments, the pressure relief structure 2 is integrally formed with the first wall 11; or, as shown in Figures 5 to 8, the pressure relief structure 2 and the first wall 11 are separately provided, and the pressure relief structure 2 is installed on the first wall 11. For example, the first wall 11 is provided with a through hole, and the pressure relief structure 2 is installed in the through hole.

[0177] When the pressure relief structure 2 is integrally formed with the first wall 11, a notched groove 11b can be provided on the first wall 11. The area of ​​the first wall 11 corresponding to the notched groove 11b forms a weak portion of the pressure relief structure 2. The weak portion is configured to crack when the battery cell 100 is depressurized. The molding method of the pressure relief structure 2 is simple and the production cost is low. It can be understood that the notched groove 11b is formed on the inner surface of the first wall 11 and / or the outer surface of the first wall 11.

[0178] It can be seen that in the above technical solution, by integrally forming the pressure relief structure 2 and the first wall 11, the pressure relief structure 2 is formed in a simple manner, which can reduce the number of components constituting the battery cell 100, simplify the structure of the battery cell 100, and reduce costs.

[0179] In the embodiment of the present application, there is no specific restriction on the shape of the notched groove 11b; for example, the notched groove 11b includes a first straight groove segment and four second straight groove segments, and the two ends of the first straight groove segment are respectively connected to two second straight groove segments set at a preset angle, so that the two ends of the notched groove 41 can roughly form a Y shape.

[0180] When the pressure relief structure 2 is separately provided from the first wall 11, the pressure relief structure 2 and the shell 1 are two separate components, which are separately formed and then installed together; the pressure relief structure 2 can be a component such as an explosion-proof plate, an explosion-proof valve, a safety valve, etc., and the pressure relief structure 2 can be installed on the first wall 11 by bonding, welding, etc. The first wall 11 is provided with a through hole, and the pressure relief structure 2 is installed in the through hole. When the internal pressure of the battery cell 100 reaches a threshold value or the temperature reaches a threshold value, the pressure relief structure 2 opens at least part of the through hole, and the emission medium inside the battery cell 100 is discharged through the through hole to release the pressure inside the battery cell 100.

[0181] It can be seen that in the above technical solution, the pressure relief structure 2 and the first wall 11 are constructed as separate parts, which facilitates the arrangement of the pressure relief structure 2 on the shell 1 , has low production difficulty and high efficiency, and can improve the production efficiency of the battery cell 100 .

[0182] For example, if the pressure relief structure 2 is a bursting disc, the disc is a sheet with at least some areas having less strength than the first wall 11. The disc covers the through-hole and is welded to the first wall 11. When the internal pressure or temperature of the battery cell 100 reaches a threshold, the disc is at least partially destroyed, thereby opening at least some of the through-holes to release the pressure within the battery cell 100.

[0183] In some embodiments, when the pressure relief structure 2 is integrally formed with the first wall 11, a groove 11a is provided on the inner surface and / or outer surface of the first wall 11, and the bottom wall of the groove 11a forms the pressure relief structure 2. In the above technical solution, by providing the groove 11a on the inner surface and / or outer surface of the first wall 11, and forming the pressure relief structure 2 on the bottom wall of the groove 11a, the processing and forming of the pressure relief structure 2 is facilitated.

[0184] Taking the first wall 11 as the bottom wall of the shell 1 as an example, the inner surface of the first wall 11 is provided with a groove 11a, then a portion of the upper surface of the first wall 11 is recessed downward to form the groove 11a, and the lower groove wall of the groove 11a is the groove bottom wall; the outer surface of the first wall 11 is provided with a groove 11a, then a portion of the lower surface of the first wall 11 is recessed upward to form the groove 11a, and the upper groove wall of the groove 11a is the groove bottom wall.

[0185] In some embodiments, when the pressure relief structure 2 is integrally formed with the first wall 11, a notch is formed on the first wall 11. The area of ​​the first wall 11 corresponding to the notch serves as a weak portion of the pressure relief structure 2, and the weak portion is configured to rupture when the battery cell 100 releases pressure. In the above technical solution, by forming the notch on the first wall 11, the area of ​​the first wall 11 corresponding to the notch serves as the weak portion of the pressure relief structure 2, thereby facilitating the processing and forming of the pressure relief structure 2.

[0186] In a second aspect, an embodiment of the present application provides a battery 200 including the above-mentioned battery cell 100 .

[0187] In the above technical solution, since the battery 200 adopts the above-mentioned battery cell 100 , it is beneficial to improve the safety of the battery 200 .

[0188] In a third aspect, an embodiment of the present application provides an electrical device 1000 , comprising the above-mentioned battery 200 , wherein the battery 200 is used to provide electrical energy.

[0189] In the above technical solution, since the power-consuming device 1000 adopts the above-mentioned battery 200 and the battery 200 has good safety in use, it is beneficial to improve the safety of the power-consuming device 1000.

[0190] Please refer to FIG. 3 to FIG. 9 again to describe the battery cell 100 according to a specific embodiment of the present application.

[0191] In an embodiment of the present application, a battery cell 100 includes a shell 1, a pressure relief structure 2, and an electrode assembly 3. The shell 1 has a first wall 11, a second wall 12, and two third walls 13 arranged opposite to each other along a third direction. The first wall 11 and the second wall 12 are arranged opposite to each other along the first direction. Each third wall 13 is adjacent to the first wall 11, and each third wall 13 is adjacent to the second wall 12. The pressure relief structure 2 is provided on the first wall 11. The electrode assembly 3 is provided in the shell 1. The electrode assembly 3 is a wound structure and includes a flat portion 3a, a first curved portion 3b, and a second curved portion 3c. The first curved portion 3b and the second curved portion 3c are respectively provided on the flat portion 3a in the first direction. At both ends, a first dividing line Ω1 is defined between the first curved portion 3b and the flat portion 3a. The first curved portion 3b is located between the flat portion 3a and the first wall 11. The surface of the first curved portion 3b facing the first wall 11 is a first arc surface. A second dividing line Ω2 is defined between the second curved portion 3c and the flat portion 3a. The second curved portion 3c is located between the flat portion 3a and the second wall 12. The surface of the second curved portion 3c facing the second wall 12 is a second arc surface. The distance between the first dividing line Ω1 and the first wall 11 is 5mm≤L≤30mm, where L is greater than or equal to the radius of the first arc surface, and L is greater than or equal to the distance L' between the second dividing line Ω2 and the second wall 12. The two side surfaces of the flat portion 3a in the third direction are both planes. The first dividing line Ω1 can correspond to a plane parallel to the first wall 11, and the second dividing line Ω can correspond to a plane parallel to the second wall 12.

[0192] In the above technical solution, when the electrode assembly 3 expands and deforms, the pulling effect on the pressure relief structure 2 on the first wall 11 can be weakened, thereby reducing the probability of the pressure relief structure 2 being damaged or failing due to pulling, while taking into account the volume energy density of the battery cell 100.

[0193] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0194] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, wherein, comprising: a housing having a first wall; a pressure relief structure provided on the first wall; an electrode assembly which is a wound electrode assembly and is provided inside the housing, the electrode assembly includes a flat portion and a first bent portion, along a first direction, the first bent portion is provided on a side of the flat portion facing the first wall; wherein, there is a first demarcation line between the first bent portion and the flat portion, the distance between the first demarcation line and the first wall is L, L≥5mm, and the first direction is perpendicular to the axial direction of the electrode assembly.

2. The battery cell according to claim 1, wherein, the housing further has a second wall, the second wall is disposed opposite to the first wall along the first direction, the electrode assembly further includes a second bent portion, along the first direction, the second bent portion is provided on a side of the flat portion facing the second wall, there is a second demarcation line between the second bent portion and the flat portion, and the distance between the first demarcation line and the first wall is greater than or equal to the distance between the second demarcation line and the second wall.

3. The battery cell according to claim 1 or 2, wherein, a boss is formed on the inner surface of the first wall, the boss is disposed opposite to the electrode assembly and is adapted to support the electrode assembly.

4. The battery cell according to any one of claims 1-3, wherein, the surface of the first bent portion facing the first wall is an arc surface, the radius of the arc surface is R, R≤L.

5. The battery cell according to any one of claims 1-4, wherein, there are multiple electrode assemblies, the axial directions of the multiple electrode assemblies are arranged in parallel, and the multiple electrode assemblies are stacked along the axial direction of the electrode assembly and / or a third direction, and the third direction is perpendicular to the axial direction of the electrode assembly and the first direction respectively.

6. The battery cell according to any one of claims 1-5, wherein, further comprising: an insulating member, at least part of the insulating member is provided between the first wall and the electrode assembly.

7. The battery cell according to claim 6, wherein, at least part of the insulating member is provided between the pressure relief structure and the electrode assembly and forms a discharge portion, and the discharge portion includes: a first communication channel which penetrates the insulating member along the first direction from a side of the insulating member facing the pressure relief structure; and / or, a second communication channel which penetrates the outer peripheral wall of the insulating member along a direction perpendicular to the first direction from a side of the insulating member facing the pressure relief structure.

8. The battery cell according to claim 7, wherein, a relief groove is formed on a side of at least part of the insulating member facing the pressure relief structure, the relief groove is disposed opposite to the pressure relief structure and is communicated with the discharge portion.

9. The battery cell according to any one of claims 1-8, wherein, L≤30mm.

10. The battery cell according to any one of claims 1-9, wherein, the thickness of the first wall is t1, 0.4mm≤t1≤2mm.

11. The battery cell according to claim 10, wherein, the width of the flat part in the first direction is b, and 150 mm ≤ b ≤ 600 mm.

12. The battery cell according to claim 10 or 11, wherein, the width of the flat part in the first direction is b, and 0.0006 ≤ t1 / b ≤ 0.0135.

13. The battery cell according to any one of claims 1-12, wherein, the multi-layer electrode sheets of the electrode assembly are stacked in the third direction, the housing has two third walls oppositely arranged in the third direction, the first wall connects the two third walls, the thickness of the first wall is t1, the thickness of the third wall is t2, t1 > t2, and the third direction is perpendicular to the axial direction of the electrode assembly and the first direction respectively.

14. The battery cell according to claim 13, wherein, 0.4 mm ≤ t1 ≤ 2 mm; and / or, 0.2 mm ≤ t2 ≤ 1.5 mm; and / or, 0.08 mm 2 ≤t1×t2≤3 mm 2 ; and / or, t1 - t2 ≤ 1.8 mm.

15. The battery cell according to any one of claims 1-14, wherein, the pressure relief structure and the pole post of the battery cell are disposed on different side walls of the housing.

16. The battery cell according to claim 15, wherein, the housing includes a housing body and a housing cover, one end of the housing body in the axial direction of the electrode assembly is open, the housing cover is disposed at the open end of the housing body, the first wall is disposed at the end of the housing body far from the open end, and the pole post is disposed on the housing cover.

17. The battery cell according to claim 15, wherein, the housing includes a housing body and a housing cover, both ends of the housing body in the axial direction of the electrode assembly are respectively open, the housing cover is disposed at the open ends of the housing body, the first wall extends to the open ends on both sides, and each housing cover is respectively provided with the pole post.

18. The battery cell according to any one of claims 1-17, wherein, the pressure relief structure is integrally formed with the first wall.

19. The battery cell according to claim 18, wherein, grooves are provided on the inner surface and / or outer surface of the first wall, and the bottom wall of the groove forms the pressure relief structure.

20. The battery cell according to claim 18 or 19, wherein, a scoring groove is formed in the first wall, and the area of the first wall corresponding to the scoring groove is configured as a weak part of the pressure relief structure, and the weak part is configured to crack when the battery cell relieves pressure.

21. The battery cell according to any one of claims 1-17, wherein, the pressure relief structure is separately provided from the first wall, and the pressure relief structure is installed on the first wall.

22. A battery, wherein, it includes the battery cell according to any one of claims 1-21.

23. An electrical device, wherein, it includes the battery according to claim 22, and the battery is used to provide electrical energy.

Images