Battery cell, manufacturing method and manufacturing system thereof, battery and electric device

Abstract

The embodiment of the invention provides a battery monomer, a manufacturing method and a manufacturing system thereof, a battery and a power utilization device. The battery cell comprises a shell, an electrode assembly and an end cover. An end portion of the housing in the first direction has an opening. The electrode assembly is accommodated in the shell and comprises a main body part and a tab connected to the main body part; the end cover is used for covering the opening. The shell comprises a first side plate, the first side plate comprises a first plate part and a second plate part which are arranged in the first direction, the second plate part is located on the side, close to the opening, of the first plate part, and the thickness of the second plate part is larger than that of the first plate part. The second plate part is used for being welded with the end cover to form a welding part; in the first direction, one end, close to the first plate part, of the second plate part exceeds the welding part; in the thickness direction of the first side plate, the main body part and the second plate part are not overlapped. According to the embodiment of the invention, the strength of the area, near the welding part, of the first side plate can be ensured, the cracking risk of the first side plate is reduced, and the safety is improved.

Description

[0001] This application is a divisional application based on the application number 202280001782.3, the application date January 14, 2022, the applicant is Contemporary Amperex Technology Co., Ltd., and the application name is "Battery Cells and Their Manufacturing Methods and Systems, Batteries and Electrical Devices". Technical Field

[0002] The present application relates to the field of battery technology, and more specifically, to a battery cell and a manufacturing method and system thereof, a battery, and an electrical device. Background Art

[0003] Battery cells are widely used in electronic devices, such as mobile phones, laptop computers, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and electric tools, etc. Battery cells can include nickel-cadmium battery cells, nickel-hydrogen battery cells, lithium-ion battery cells, and secondary alkaline zinc-manganese battery cells, etc.

[0004] In the development of battery technology, in addition to improving the performance of battery cells, safety is also an issue that cannot be ignored. If the safety of battery cells cannot be guaranteed, the battery cells cannot be used. Therefore, how to enhance the safety of battery cells is a technical problem that needs to be solved urgently in battery technology. Summary of the invention

[0005] The present application provides a battery cell and a manufacturing method and system thereof, a battery, and an electrical device, which can enhance the safety of the battery cell.

[0006] In a first aspect, an embodiment of the present application provides a battery cell, comprising a shell, an electrode assembly, and an end cover. The shell has an opening at an end along a first direction. The electrode assembly is accommodated in the shell, and the electrode assembly includes a main body and a pole ear connected to the main body. The end cover is used to cover the opening. The shell includes a first side plate, the first side plate includes a first plate portion and a second plate portion arranged along a first direction, the second plate portion is located on a side of the first plate portion close to the opening, and the thickness of the second plate portion is greater than the thickness of the first plate portion. The second plate portion is used to weld with the end cover and form a welding portion; in the first direction, an end of the second plate portion close to the first plate portion exceeds the welding portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap.

[0007] The present application increases the thickness of the second plate portion near the opening and makes one end of the second plate portion near the first plate portion extend beyond the welding portion to ensure the strength of the first side plate near the welding portion, thereby reducing the risk of cracking of the first side plate and improving safety. The main body and the second plate portion do not overlap in the thickness direction of the first side plate, thereby reducing the risk of the main body portion directly colliding with or squeezing the second plate portion, thereby further reducing the risk of cracking of the second plate portion and improving safety.

[0008] In some embodiments, the second plate portion protrudes from the inner surface of the first plate portion.

[0009] In the above embodiment, when the thickness of the second plate portion is constant, the second plate portion protrudes from the inner surface of the first plate portion, which can reduce the size of the second plate portion protruding from the outer surface of the first plate portion, thereby reducing the maximum size of the shell, making full use of the internal space of the shell, and improving the energy density of the battery cell.

[0010] In some embodiments, the battery cell further comprises an insulating member disposed between the end cover and the main body and abutting against the main body. In the first direction, an end of the second plate portion close to the first plate portion does not exceed a surface of the insulating member abutting against the main body.

[0011] In the above embodiment, the insulating member can insulate and isolate the end cap from the main body to reduce the risk of the end cap connecting the positive and negative electrode sheets in the main body and improve safety. The insulating member and the main body are against each other along the first direction to reduce the shaking amplitude of the main body when the battery cell vibrates, reduce the risk of misalignment of the positive and negative electrode sheets, and improve the charge and discharge performance of the electrode assembly. The insulating member can limit the position of the main body along the first direction to reduce the possibility of the main body colliding with the second plate when the battery cell vibrates, and reduce the risk of cracking the second plate.

[0012] In some embodiments, an outer surface of the first plate portion is flush with an outer surface of the second plate portion.

[0013] The above implementation can ensure the flatness of the outer surface of the first side plate and improve the appearance of the shell.

[0014] In some embodiments, the second plate portion includes a base portion and a first transition portion, wherein the first transition portion is connected between the base portion and the first plate portion; and a thickness of the first transition portion gradually decreases in a direction away from the base portion.

[0015] In the above embodiment, by providing the first transition portion, a smooth transition can be achieved at the junction of the first plate portion and the second plate portion, thereby reducing stress concentration and the risk of cracking of the first side plate.

[0016] In some embodiments, the second plate portion is connected to at least a middle region of the first plate portion along a second direction, and the second direction is perpendicular to the first direction and the thickness direction.

[0017] During the charging process of the electrode assembly, the main body will expand and squeeze the first plate portion; during the discharging process of the electrode assembly, the main body will shrink. Therefore, the expansion and contraction of the main body will cause the first side plate to swing back and forth with the welding portion as the base point. The middle part of the main body along the second direction expands more, and the swing amplitude of the middle area of ​​the first side plate along the second direction is also larger. Therefore, the area of ​​the first side plate located in the middle along the second direction and close to the welding portion is prone to cracking under the combined action of thermal stress and swing stress. In the above embodiment, the second plate portion is at least connected to the middle area of ​​the first plate portion along the second direction, so that the strength of the area of ​​the first side plate that is subjected to greater force can be strengthened to reduce the risk of cracking of the first side plate.

[0018] In some embodiments, the second plate portion is continuously arranged in the second direction, and an edge of the second plate portion along the second direction is flush with an edge of the first plate portion along the second direction.

[0019] In the above embodiment, the end portion of the first side plate close to the opening is thickened as a whole to further reduce the risk of cracking of the first side plate.

[0020] In some embodiments, the second plate portion includes a base portion and two second transition portions, and the two second transition portions are respectively located at two ends of the base portion along the second direction; the thickness of the second transition portion gradually decreases in a direction away from the base portion.

[0021] In the above embodiment, by providing the second transition portion, a smooth transition can be achieved at the junction of the second plate portion and other portions of the shell, thereby reducing stress concentration and the risk of cracking of the first side plate.

[0022] In some embodiments, the housing includes two first side plates arranged opposite to each other in the thickness direction and two second side plates arranged opposite to each other in the second direction, and the first direction, the second direction and the thickness direction are perpendicular to each other. The second side plate is provided with a recessed portion, which is recessed from the end surface of the second side plate along the first direction; a portion of the end cover is accommodated in the recessed portion and abuts against the bottom surface of the recessed portion. The thickness of the portion of the second side plate corresponding to the side surface of the recessed portion is greater than the thickness of the first plate portion.

[0023] In the above embodiment, the bottom surface of the recess can support the end cover and limit the end cover when the end cover is inserted into the shell, so as to prevent the end cover from excessively extending into the shell. The portion of the second side plate corresponding to the side of the recess can be used for welding with the end cover. Even if the recess is provided on the second side plate in this embodiment, the strength of the portion of the second side plate corresponding to the side of the recess can be ensured, thereby reducing the risk of cracking of the second side plate.

[0024] In some embodiments, in the first direction, an end of the second plate portion close to the first plate portion exceeds the bottom surface of the recessed portion.

[0025] The bottom surface of the recess is used to support the end cap, so the bottom surface of the recess will also limit the position of the end cap. In the above embodiment, the end of the second plate portion close to the first plate portion exceeds the bottom surface of the recess, so that the end of the second plate portion close to the first plate portion exceeds the end cap and the welding portion, thereby ensuring the strength of the first side plate in the area near the welding portion, reducing the risk of cracking of the first side plate, and improving safety.

[0026] In some embodiments, the electrode assembly is a wound structure and includes a straight region, and the electrode sheet of the electrode assembly includes a plurality of straight portions located in the straight region, and the plurality of straight portions are stacked along a thickness direction.

[0027] The electrode assembly expands the most along the stacking direction of the straight portion, so the first side plate is subjected to a greater force; the above embodiment increases the thickness of the second plate portion to reduce the risk of cracking of the first side plate.

[0028] In some embodiments, the electrode assembly includes a plurality of pole pieces, and the plurality of pole pieces are stacked in a thickness direction.

[0029] In the above embodiment, the electrode assembly expands the most along the stacking direction of the multiple pole pieces, so the first side plate is subjected to a greater force; the above embodiment increases the thickness of the second plate portion to reduce the risk of cracking of the first side plate.

[0030] In some embodiments, in the first direction, a ratio of a dimension L1 of the welding portion to an overall dimension L2 of the second plate portion is 0.1-0.5.

[0031] The smaller the value of L1 / L2, the lower the connection strength between the end cap and the second plate portion; if the value of L1 / L2 is too small, the connection failure between the end cap and the second plate portion is likely to occur. The larger the value of L1 / L2, the smaller the spacing between the welding portion and the first plate portion; if the value of L1 / L2 is too large, the thermal stress generated by welding may be transferred to the first plate portion, thereby causing the risk of cracking of the first plate portion. The above embodiment limits the value of L1 / L2 to 0.1-0.5 to ensure the connection strength between the end cap and the second plate portion and the strength of the first plate portion.

[0032] In some embodiments, a ratio of the thickness of the second plate portion to the thickness of the first plate portion is 1.05-3.

[0033] When the thickness of the first plate portion is constant, the greater the thickness of the second plate portion, the higher the strength of the second plate portion, and the less likely the second plate portion is to crack. Of course, the greater the thickness of the second plate portion, the greater the space occupied by the second plate portion, the greater the weight of the shell, and the lower the energy density of the battery cell. The above embodiment limits the ratio of the thickness of the second plate portion to the first plate portion to 1.05-3 to balance the strength of the second plate portion and the energy density of the battery cell.

[0034] In a second aspect, an embodiment of the present application provides a battery comprising a plurality of battery cells according to any one of the embodiments of the first aspect.

[0035] In a third aspect, an embodiment of the present application provides an electrical device, comprising a battery cell according to any embodiment of the first aspect, wherein the battery cell is used to provide electrical energy.

[0036] In a fourth aspect, an embodiment of the present application provides a method for manufacturing a battery cell, comprising:

[0037] A shell is provided, wherein an end of the shell along a first direction has an opening, the shell comprises a first side plate, the first side plate comprises a first plate portion and a second plate portion arranged along the first direction, the second plate portion is located on a side of the first plate portion close to the opening, and the thickness of the second plate portion is greater than the thickness of the first plate portion;

[0038] Providing an electrode assembly and an end cap, wherein the electrode assembly includes a main body and a tab connected to the main body;

[0039] installing the electrode assembly into the housing;

[0040] Covering the opening with the end cover, welding the second plate portion and the end cover to form a welded portion;

[0041] Wherein, in the first direction, one end of the second plate portion close to the first plate portion exceeds the welding portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap.

[0042] In a fifth aspect, an embodiment of the present application provides a manufacturing system for a battery cell, comprising a first providing device, a second providing device, a first assembling device and a second assembling device. The first providing device is used to provide a shell, the end of the shell along the first direction has an opening, the shell comprises a first side plate, the first side plate comprises a first plate portion and a second plate portion arranged along the first direction, the second plate portion is located on a side of the first plate portion close to the opening, and the thickness of the second plate portion is greater than the thickness of the first plate portion. The second providing device is used to provide an electrode assembly and an end cap, the electrode assembly comprises a main body portion and a pole ear connected to the main body portion. The first assembling device is used to install the electrode assembly into the shell. The second assembling device is used to cover the end cap on the opening, weld the second plate portion and the end cap and form a welded portion. In the first direction, one end of the second plate portion close to the first plate portion exceeds the welded portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0044] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0045] Figure 2 An exploded schematic diagram of a battery provided in some embodiments of the present application;

[0046] Figure 3 for Figure 2 A schematic diagram of the structure of the battery module shown;

[0047] Figure 4 An exploded schematic diagram of a battery cell provided in some embodiments of the present application;

[0048] Figure 5 A schematic top view of a battery cell provided in some embodiments of the present application;

[0049] Figure 6 for Figure 5 The schematic cross-sectional view of the battery cell shown is made along the AA direction;

[0050] Figure 7 for Figure 6 An enlarged schematic diagram of a battery cell at a circle C is shown;

[0051] Figure 8 A schematic top view of a housing of a battery cell provided in some embodiments of the present application;

[0052] Fig. 9 for Figure 5 The schematic cross-sectional view of the battery cell shown is made along the BB direction;

[0053] Fig.10 for Fig. 9 An enlarged schematic diagram of a battery cell at a circle D is shown;

[0054] Fig.11 A schematic diagram of the structure of a battery cell housing provided in some embodiments of the present application;

[0055] Fig.12 for Fig.11 An enlarged schematic diagram of the housing shown at the circle E;

[0056] Fig.13 A schematic diagram of the structure of an electrode assembly of a battery cell provided in some embodiments of the present application;

[0057] Fig.14 A schematic diagram of the structure of an electrode assembly of a battery cell provided in some other embodiments of the present application;

[0058] Fig.15A schematic diagram of a process for manufacturing a battery cell provided in some embodiments of the present application;

[0059] Fig.16 A schematic block diagram of a manufacturing system for an electrode assembly provided in some embodiments of the present application.

[0060] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0062] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. 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 and secondary relationship.

[0063] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0064] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0065] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0066] 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 thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0067] The term "plurality" used in the present application refers to two or more (including two).

[0068] In the present application, the term "parallel" includes not only the absolutely parallel situation, but also the roughly parallel situation conventionally recognized in engineering; meanwhile, "vertical" includes not only the absolutely vertical situation, but also the roughly vertical situation conventionally recognized in engineering.

[0069] In the present application, the battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells or magnesium-ion battery cells, etc., and the embodiments of the present application are not limited to this.

[0070] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may be a battery module or a battery pack. The battery generally includes a box for encapsulating one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

[0071] A battery cell includes an electrode assembly and an electrolyte, and the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell mainly works by the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive current collector and a positive active material layer, and the positive active material layer is coated on the surface of the positive current collector; the positive current collector includes a positive current collector and a positive electrode tab, and the positive current collector is coated with a positive active material layer, and the positive electrode tab is not coated with the positive active material layer. Taking a lithium-ion battery as an example, the material of the positive current collector may be aluminum, and the positive active material layer includes a positive active material, and the positive active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode sheet includes a negative current collector and a negative active material layer, and the negative active material layer is coated on the surface of the negative current collector; the negative current collector includes a negative current collector and a negative electrode tab, and the negative current collector is coated with a negative active material layer, and the negative electrode tab is not coated with a negative active material layer. The negative electrode current collector may be made of copper, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material may be carbon or silicon, etc. The separator may be made of PP (polypropylene) or PE (polyethylene), etc.

[0072] The battery cell further includes a shell and an end cover. The shell has an opening. The end cover covers the opening and is sealed to form a sealed space for accommodating the electrode assembly and the electrolyte.

[0073] In the related art, the shell and the end cover are connected by welding, which can not only ensure the connection strength between the shell and the end cover, but also achieve the sealing between the shell and the end cover.

[0074] The inventors found that after welding, a heat-affected zone will form near the molten pool in the shell, and the heat-affected zone will be affected by residual thermal stress, resulting in lower strength in the heat-affected zone than in other areas. When the heat-affected zone is squeezed during the use of the battery cell, the shell may crack in the heat-affected zone, causing electrolyte leakage, resulting in battery cell failure, and posing safety risks.

[0075] In view of this, an embodiment of the present application provides a battery cell, which includes a shell, an electrode assembly and an end cover. The shell has an opening at the end along the first direction. The electrode assembly is accommodated in the shell, and the electrode assembly includes a main body and a pole ear connected to the main body. The end cover is used to cover the opening. The shell includes a first side plate, and the first side plate includes a first plate portion and a second plate portion arranged along the first direction, the second plate portion is located on the side of the first plate portion close to the opening, and the thickness of the second plate portion is greater than the thickness of the first plate portion. The second plate portion is used to weld with the end cover and form a welding portion. In the first direction, one end of the second plate portion close to the first plate portion exceeds the welding portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap. In this embodiment, the thickness of the second plate portion close to the opening is increased to ensure the strength of the first side plate in the area near the welding portion, so as to reduce the risk of cracking of the first side plate and improve safety. The main body portion and the second plate portion do not overlap in the thickness direction of the first side plate, which can reduce the risk of direct collision or compression of the main body portion with the second plate portion, thereby reducing the risk of cracking of the second plate portion.

[0076] The battery cells described in the embodiments of the present application are suitable for use in batteries and electrical devices using the batteries.

[0077] The electrical device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle may be a fuel vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, and the like; the spacecraft may include an airplane, a rocket, a space shuttle, and 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 electric tool may include a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and an electric tool for railways, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator, and an electric planer, and the like. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0078] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0079] Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application.

[0080] like Figure 1 As shown, a battery 2 is disposed inside the vehicle 1, and the battery 2 may be disposed at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1, for example, the battery 2 may be used as an operating power source for the vehicle 1.

[0081] The vehicle 1 may further include a controller 3 and a motor 4 , wherein the controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of starting, navigating, and driving the vehicle 1 .

[0082] In some embodiments of the present application, the battery 2 can not only serve as an operating power source for the vehicle 1, but also serve as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0083] Figure 2 An exploded schematic diagram of a battery provided for some embodiments of the present application.

[0084] like Figure 2 As shown, the battery 2 includes a box 5 and a battery cell ( Figure 2 The battery cells are contained in the box body 5.

[0085] The box 5 is used to accommodate the battery cells, and the box 5 can be of various structures. In some embodiments, the box 5 can include a first box portion 5a and a second box portion 5b, the first box portion 5a and the second box portion 5b cover each other, and the first box portion 5a and the second box portion 5b jointly define a storage space 5c for accommodating the battery cells. The second box portion 5b can be a hollow structure with one end open, the first box portion 5a is a plate-like structure, and the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c; the first box portion 5a and the second box portion 5b can also be hollow structures with one side open, and the open side of the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c. Of course, the first box portion 5a and the second box portion 5b can be of various shapes, such as a cylinder, a cuboid, etc.

[0086] In order to improve the sealing performance after the first box body part 5a and the second box body part 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body part 5a and the second box body part 5b.

[0087] Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box.

[0088] In the battery 2, there can be one or more battery cells. If there are multiple battery cells, the multiple battery cells can be connected in series, in parallel, or in mixed connection. Mixed connection means that the multiple battery cells are both connected in series and in parallel. The multiple battery cells can be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple battery cells is accommodated in the box 5; of course, multiple battery cells can also be connected in series, in parallel, or in mixed connection to form a battery module 6, and the multiple battery modules 6 are then connected in series, in parallel, or in mixed connection to form a whole, and accommodated in the box 5.

[0089] Figure 3 for Figure 2 Schematic diagram of the structure of the battery module shown.

[0090] like Figure 3 As shown, in some embodiments, there are multiple battery cells 7, and the multiple battery cells 7 are first connected in series, in parallel, or in mixed connection to form a battery module 6. The multiple battery modules 6 are then connected in series, in parallel, or in mixed connection to form a whole, and are accommodated in a box.

[0091] The multiple battery cells 7 in the battery module 6 can be electrically connected through a busbar component to achieve parallel connection, series connection or mixed connection of the multiple battery cells 7 in the battery module 6 .

[0092] Figure 4 An exploded schematic diagram of a battery cell provided in some embodiments of the present application; Figure 5 A schematic top view of a battery cell provided in some embodiments of the present application; Figure 6 for Figure 5 The schematic cross-sectional view of the battery cell shown is made along the AA direction; Figure 7 for Figure 6 An enlarged schematic diagram of a battery cell at circle C is shown.

[0093] like Figures 4 to 7 As shown, the embodiment of the present application provides a battery cell 7, which includes a shell 20, an electrode assembly 10 and an end cover 30. The shell 20 has an opening 20a at the end along the first direction X. The electrode assembly 10 is accommodated in the shell 20, and the electrode assembly 10 includes a main body 11 and a pole ear 12 connected to the main body 11. The end cover 30 is used to cover the opening 20a. The shell 20 includes a first side plate 21, and the first side plate 21 includes a first plate portion 211 and a second plate portion 212 arranged along the first direction X. The second plate portion 212 is located on a side of the first plate portion 211 close to the opening 20a, and the thickness of the second plate portion 212 is greater than the thickness of the first plate portion 211. The second plate portion 212 is used to weld with the end cover 30 and form a welding portion W; in the first direction X, one end of the second plate portion 212 close to the first plate portion 211 exceeds the welding portion W; in the thickness direction Y of the first side plate 21, the main body 11 and the second plate portion 212 do not overlap.

[0094] The shell 20 is a hollow structure, and a receiving cavity for receiving the electrode assembly 10 and the electrolyte is formed inside. The shell 20 can be in various shapes, such as a cylinder, a cuboid, etc. The shape of the shell 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a cylindrical structure, a cylindrical shell can be selected; if the electrode assembly 10 is a cuboid structure, a cuboid shell can be selected.

[0095] The end cap 30 is sealed and connected to the housing 20 to form a sealed space for accommodating the electrode assembly 10 and the electrolyte. Exemplarily, the end cap 30 is connected to the housing 20 by welding. Welding can simultaneously achieve sealing and fixing between the end cap 30 and the housing 20.

[0096] In some examples, the housing 20 has an opening 20a at one end along the first direction X, and one end cap 30 is provided to cover the opening 20a of the housing 20. In other examples, the housing 20 has an opening 20a at both ends along the first direction X, and two end caps 30 are provided, and the two end caps 30 cover the two openings 20a of the housing 20 respectively.

[0097] Exemplarily, the first direction X is parallel to the thickness direction of the end cover 30 .

[0098] The electrode assembly 10 is a core component for realizing the charge and discharge functions of the battery cell 7, and includes a first pole piece, a second pole piece, and a separator. The first pole piece and the second pole piece have opposite polarities, and the separator is used to insulate and isolate the first pole piece from the second pole piece. The electrode assembly 10 mainly works by moving metal ions between the first pole piece and the second pole piece.

[0099] One of the first pole piece and the second pole piece is a positive pole piece, and the other of the first pole piece and the second pole piece is a negative pole piece.

[0100] The electrode assembly 10 may be a wound structure, a laminated structure or other structures. The first electrode sheet may be one or more, and the second electrode sheet may be one or more. The number of the first electrode sheet and the second electrode sheet may be determined according to the structure of the electrode assembly 10.

[0101] The number of electrode assemblies 10 may be one or more, which is not limited in this embodiment.

[0102] The main body 11 is the electricity generating part of the electrode assembly 10. The active material inside it is used to react electrochemically with the electrolyte to generate the charge and discharge process. The tab 12 is led out from the end of the main body 11 and is used to conduct the electricity generated by the main body 11.

[0103] The main body 11 includes a positive electrode current collector, a positive electrode active material layer, a negative electrode current collector, a negative electrode active material layer and a separator, and the tabs 12 include a positive electrode tab and a negative electrode tab.

[0104] Exemplarily, the first side plate 21 is substantially a plate-shaped structure parallel to the first direction X.

[0105] The housing 20 may include one or more first side panels 21. For example, for a rectangular housing 20, there may be two first side panels 21, and the two first side panels 21 are arranged opposite to each other. For a cylindrical housing 20, there may be one first side panel 21, and the first side panel 21 is generally a cylindrical structure.

[0106] The second plate portion 212 may be disposed on one side of the first plate portion 211 along the first direction X, or may be disposed on both sides of the first plate portion 211 along the first direction X.

[0107] In some examples, the housing 20 has an opening 20a at one end along the first direction X, the second plate portion 212 is disposed on one side of the first plate portion 211 along the first direction X, and one end cover 30 is provided and welded to the second plate portion 212. In other examples, the housing 20 has an opening 20a at both ends along the first direction X, two second plate portions 212 are respectively disposed on both sides of the first plate portion 211 along the first direction X, two end covers 30 are provided, and the two end covers 30 are respectively welded to the two second plate portions 212.

[0108] The thickness of the second plate portion 212 is greater than that of the first plate portion 211 , so that the second plate portion 212 has a higher strength. The second plate portion 212 may protrude from either the inner surface of the first plate portion 211 or the outer surface of the first plate portion 211 .

[0109] In this embodiment, in a plane perpendicular to the thickness direction Y of the first side plate 21 , the projection of the main body portion 11 does not overlap with the projection of the second plate portion 212 .

[0110] The second plate portion 212 extends beyond the welding portion W in a direction parallel to the first direction X and gradually approaches the first plate portion 211 .

[0111] After the welding portion W is formed, thermal stress will remain in the area of ​​the second plate portion 212 near the welding portion W. In this embodiment, the thickness of the second plate portion 212 near the opening 20a is increased, and one end of the second plate portion 212 near the first plate portion 211 is made to extend beyond the welding portion W, so as to ensure the strength of the area of ​​the first side plate 21 near the welding portion W, reduce the risk of cracking of the first side plate 21, and improve safety. The main body 11 and the second plate portion 212 do not overlap in the thickness direction Y of the first side plate 21, so as to reduce the risk of the main body 11 directly colliding with or squeezing the second plate portion 212, thereby further reducing the risk of cracking of the second plate portion 212 and improving safety.

[0112] In this embodiment, only the thickness of the second plate portion 212 is increased. Compared with the solution of increasing the thickness of the first side plate 21 as a whole, this embodiment can reduce the weight of the housing 20 and improve the energy density of the battery cell 7 .

[0113] In some embodiments, the battery cell 7 further includes two electrode terminals 40 mounted on the end cover 30 , and the two electrode terminals 40 are respectively used to be electrically connected to the first pole piece and the second pole piece to conduct the electrical energy generated by the electrode assembly 10 .

[0114] In some embodiments, the second plate portion 212 protrudes from the inner surface of the first plate portion 211. When the thickness of the second plate portion 212 is constant, the second plate portion 212 protrudes from the inner surface of the first plate portion 211, which can reduce the size of the second plate portion 212 protruding from the outer surface of the first plate portion 211, thereby reducing the maximum size of the housing 20, making full use of the internal space of the housing 20, and improving the energy density of the battery cell 7.

[0115] The inner surface of the first plate portion 211 is a surface of the first plate portion 211 facing the electrode assembly 10 , and the outer surface of the first plate portion 211 is a surface of the first plate portion 211 facing away from the electrode assembly 10 .

[0116] In this embodiment, the main body 11 and the second plate portion 212 do not overlap in the thickness direction Y of the first side plate 21. This can reduce the risk of the second plate portion 212 protruding from the inner surface of the first plate portion 211 squeezing the main body 11, reduce the stress on the main body 11, and improve the charging and discharging performance of the main body 11.

[0117] In some embodiments, the first plate portion 211 is a flat plate structure with uniform thickness.

[0118] In some embodiments, the outer surface of the first plate portion 211 is flush with the outer surface of the second plate portion 212. This embodiment can ensure the flatness of the outer surface of the first side plate 21 and improve the appearance of the housing 20.

[0119] In some embodiments, the battery cell 7 further includes an insulating member 50, which is disposed between the end cover 30 and the main body 11 and abuts against the main body 11. In the first direction X, the end of the second plate portion 212 close to the first plate portion 211 does not exceed the surface of the insulating member 50 abutting against the main body 11.

[0120] In this embodiment, the insulating member 50 can insulate and isolate the end cap 30 from the main body 11 to reduce the risk of the end cap 30 connecting the positive and negative electrodes in the main body 11 and improve safety. The insulating member 50 and the main body 11 are against each other along the first direction X to reduce the shaking amplitude of the main body 11 when the battery cell 7 vibrates, reduce the risk of misalignment of the positive and negative electrodes, and improve the charge and discharge performance of the electrode assembly 10. The insulating member 50 can limit the position of the main body 11 along the first direction X to reduce the possibility of the main body 11 colliding with the second plate 212 when the battery cell 7 vibrates, and reduce the risk of cracking the second plate 212.

[0121] In some embodiments, the second plate portion 212 includes a base portion 212a and a first transition portion 212b, wherein the first transition portion 212b is connected between the base portion 212a and the first plate portion 211. The thickness of the first transition portion 212b gradually decreases in a direction away from the base portion 212a.

[0122] The base portion 212 a is used to be welded to the end cover 30 to form a welded portion W.

[0123] In this embodiment, by providing the first transition portion 212 b , a smooth transition can be achieved at the junction of the first plate portion 211 and the second plate portion 212 , thereby reducing stress concentration and the risk of cracking of the first side plate 21 .

[0124] In some embodiments, the first transition portion 212 b is formed by providing a rounded corner or a chamfer on the second plate portion 212 .

[0125] The thickness of one end of the first transition portion 212 b connected to the base portion 212 a is equal to the thickness of the base portion 212 a , and the thickness of one end of the first transition portion 212 b connected to the first plate portion 211 is equal to the thickness of the first plate portion 211 .

[0126] In some embodiments, in the first direction X, a ratio of a dimension L1 of the welding portion W to an overall dimension L2 of the second plate portion 212 is 0.1-0.5.

[0127] The smaller the value of L1 / L2, the lower the connection strength between the end cap 30 and the second plate portion 212; if the value of L1 / L2 is too small, the connection failure between the end cap 30 and the second plate portion 212 is likely to occur. The larger the value of L1 / L2, the smaller the spacing between the welding portion W and the first plate portion 211; if the value of L1 / L2 is too large, the thermal stress generated by welding may be transferred to the first plate portion 211, thereby causing the risk of cracking of the first plate portion 211. After experiments, the inventors limited the value of L1 / L2 to 0.1-0.5 to ensure the connection strength between the end cap 30 and the second plate portion 212 and the strength of the first plate portion 211.

[0128] In some embodiments, the value of L1 is 0.5 mm-2 mm, and the value of L2 is 3 mm-8 mm.

[0129] In some embodiments, a ratio of the thickness of the second plate portion 212 to the thickness of the first plate portion 211 is 1.05-3.

[0130] When the thickness of the first plate portion 211 is constant, the greater the thickness of the second plate portion 212, the higher the strength of the second plate portion 212, and the less likely the second plate portion 212 is to crack. Of course, the greater the thickness of the second plate portion 212, the greater the space occupied by the second plate portion 212, the greater the weight of the housing 20, and the lower the energy density of the battery cell 7. In this embodiment, the ratio of the thickness of the second plate portion 212 to the first plate portion 211 is limited to 1.05-3 to balance the strength of the second plate portion 212 and the energy density of the battery cell 7.

[0131] Optionally, the thickness of the base portion 212 a is used as the thickness of the second plate portion 212 .

[0132] In some embodiments, the thickness of the first plate portion 211 is 0.4 mm-0.6 mm, and the thickness of the first plate portion 211 is 0.7 mm-0.8 mm.

[0133] Figure 8 A schematic top view of a housing of a battery cell provided in some embodiments of the present application.

[0134] like Figure 7 and Figure 8 As shown, in some embodiments, the second plate portion 212 is connected to at least a middle region of the first plate portion 211 along a second direction Z, and the second direction Z is perpendicular to the first direction X and the thickness direction Y.

[0135] During the charging process of the electrode assembly 10, the main body 11 will expand and squeeze the first plate portion 211; during the discharging process of the electrode assembly 10, the main body 11 will shrink. Therefore, the expansion and shrinkage of the main body 11 will cause the first side plate 21 to swing back and forth with the welding portion W as the base point. The main body 11 expands more in the middle along the second direction Z, and the swing amplitude of the middle area of ​​the first side plate 21 along the second direction Z is also larger. Therefore, the area of ​​the first side plate 21 located in the middle along the second direction Z and close to the welding portion W is prone to cracking under the combined action of thermal stress and swing stress.

[0136] In this embodiment, the second plate portion 212 is at least connected to the middle region of the first plate portion 211 along the second direction Z, so that the strength of the region of the first side plate 21 subjected to greater force can be enhanced to reduce the risk of cracking of the first side plate 21 .

[0137] In this embodiment, a center line of the first side plate 21 along the second direction Z passes through the second plate portion 212 , and the center line is parallel to the first direction X.

[0138] In some embodiments, a ratio of a size of the second plate portion 212 along the second direction Z to a size of the first plate portion 211 along the second direction Z is 0.3-1.

[0139] In some embodiments, the second plate portions 212 are continuously arranged in the second direction Z, and the edge of the second plate portion 212 along the second direction Z is flush with the edge of the first plate portion 211 along the second direction Z.

[0140] In this embodiment, the end portion of the first side plate 21 close to the opening is thickened as a whole to further reduce the risk of cracking of the first side plate 21 .

[0141] In some embodiments, the second plate portion 212 includes a base portion 212a and two second transition portions 212c, which are respectively located at two ends of the base portion 212a along the second direction Z. The thickness of the second transition portion 212c gradually decreases in a direction away from the base portion 212a.

[0142] In this embodiment, by providing the second transition portion 212c, a smooth transition can be achieved at the junction of the second plate portion 212 and other parts of the shell 20 (such as the second side plate described later), thereby reducing stress concentration and the risk of cracking of the first side plate 21.

[0143] In some embodiments, the second transition portion 212 c is formed by providing a rounded corner or a chamfer on the second plate portion 212 .

[0144] Fig. 9 for Figure 5 The schematic cross-sectional view of the battery cell shown is made along the BB direction; Fig.10 for Fig. 9 An enlarged schematic diagram of a battery cell at a circle D is shown; Fig.11 A schematic diagram of the structure of a battery cell housing provided in some embodiments of the present application; Fig.12 for Fig.11 An enlarged schematic diagram of the shell at circle E is shown.

[0145] like Figures 9 to 12 As shown, in some embodiments, the housing 20 includes two first side plates 21 arranged opposite to each other along the thickness direction Y and two second side plates 22 arranged opposite to each other along the second direction Z, and the first direction X, the second direction Z and the thickness direction Y are perpendicular to each other. The second side plate 22 is provided with a recess 221, and the recess 221 is recessed from the end surface of the second side plate 22 along the first direction X. A portion of the end cover 30 is accommodated in the recess 221 and abuts against the bottom surface of the recess 221. The thickness of the portion of the second side plate 22 corresponding to the side surface of the recess 221 is greater than the thickness of the first plate portion 211.

[0146] The first side plate 21 may be directly connected to the second side plate 22 , or may be indirectly connected to the second side plate 22 via other structures of the housing 20 .

[0147] Exemplarily, the bottom surface of the recess 221 may be a plane, and the angle between the bottom surface of the recess 221 and the side surface of the recess 221 may be 80°-170°.

[0148] In this embodiment, the bottom surface of the recess 221 can support the end cover 30, and can limit the end cover 30 when the end cover 30 extends into the shell 20, so as to prevent the end cover 30 from excessively extending into the shell 20. The portion of the second side plate 22 corresponding to the side of the recess 221 can be used for welding with the end cover 30. Even if the recess 221 is provided on the second side plate 22 in this embodiment, the strength of the portion of the second side plate 22 corresponding to the side of the recess 221 can be ensured, thereby reducing the risk of cracking of the second side plate 22.

[0149] In some embodiments, the housing 20 further includes an arc-shaped transition plate 23 , and the transition plate 23 connects the adjacent first side plate 21 and the second side plate 22 .

[0150] In some embodiments, the transition plate 23 is also provided with a recessed portion, and the recessed portion of the transition plate 23 is recessed from an end surface of the transition plate 23 along the first direction X. Exemplarily, the recessed portion of the transition plate 23 is in communication with the recessed portion 221 of the second side plate 22 .

[0151] In some embodiments, in the first direction X, one end of the second plate portion 212 close to the first plate portion 211 exceeds the bottom surface of the recess 221 .

[0152] The bottom surface of the recessed portion 221 is used to support the end cover 30, so the bottom surface of the recessed portion 221 also limits the position of the end cover 30. In this embodiment, the end of the second plate portion 212 close to the first plate portion 211 exceeds the bottom surface of the recessed portion 221, so that the end of the second plate portion 212 close to the first plate portion 211 can exceed the end cover 30 and the welding portion W, thereby ensuring the strength of the first side plate 21 near the welding portion W, reducing the risk of cracking of the first side plate 21, and improving safety.

[0153] Fig.13 A schematic diagram of the structure of an electrode assembly of a battery cell provided in some embodiments of the present application.

[0154] like Fig.13 As shown, in some embodiments, the electrode assembly 10 is a winding structure and includes a straight region 10a. The electrode assembly 10 includes a pole piece 13, and the pole piece 13 includes a plurality of straight portions 131 located in the straight region 10a. The plurality of straight portions 131 are stacked along the thickness direction Y.

[0155] The straight region 10a is a region of the electrode assembly 10 having a straight structure, and the portion of the electrode sheet 13 located in the straight region 10a (i.e., the straight portion 131) is substantially straightly arranged. A plurality of straight portions 131 are stacked along the thickness direction Y. Exemplarily, the straight portion 131 is substantially in the shape of a plate.

[0156] During the charging process of the electrode assembly 10, the electrode sheet 13 will expand along its thickness direction Y. In the wound electrode assembly 10, the electrode assembly 10 expands the most along the stacking direction of the straight portion 131, so the first side plate is subjected to a greater force; the embodiment of the present application increases the thickness of the second plate portion to reduce the risk of cracking of the first side plate.

[0157] In some embodiments, the electrode assembly 10 further includes a bending region 10b, and the electrode piece 13 further includes a bending portion 132 located in the bending region 10b. The bending region 10b is a region where the electrode assembly 10 has a bending structure, and the portion of the electrode piece 13 located in the bending region 10b (i.e., the bending portion 132) is bent. Exemplarily, the bending portion 132 is generally bent into an arc shape.

[0158] In some embodiments, the electrode sheet 13 includes a positive electrode sheet and a negative electrode sheet. In this embodiment, the positive electrode sheet, the separator 14 and the negative electrode sheet can be stacked in sequence and wound more than two times to form an electrode assembly 10. The electrode assembly 10 is flat. The positive electrode sheet and the negative electrode sheet each include a straight portion 131 and a bent portion 132.

[0159] Fig.14 Schematic diagram of the structure of the electrode assembly of the battery cell provided in some other embodiments of the present application.

[0160] like Fig.14 As shown, in some embodiments, the electrode assembly 10 includes a plurality of pole pieces 13, and the plurality of pole pieces 13 are stacked along the thickness direction Y.

[0161] During the charging process of the electrode assembly 10, the pole piece 13 will expand along its thickness direction Y. In this embodiment, the electrode assembly 10 expands the most along the stacking direction of the plurality of pole pieces 13, so the first side plate is subjected to a greater force; the embodiment of the present application increases the thickness of the second plate portion to reduce the risk of cracking of the first side plate.

[0162] In some embodiments, the electrode assembly 10 includes a plurality of positive electrode sheets and a plurality of negative electrode sheets, and the plurality of positive electrode sheets and the plurality of negative electrode sheets are alternately stacked.

[0163] In other embodiments, the electrode assembly 10 includes a plurality of positive electrode sheets and a negative electrode sheet, the negative electrode sheet is continuously bent to form a plurality of negative electrode stacking segments, and the plurality of negative electrode stacking segments and the plurality of positive electrode sheets are alternately stacked.

[0164] Fig.15 A schematic flow chart of a method for manufacturing a battery cell provided in some embodiments of the present application.

[0165] like Fig.15 As shown, the embodiment of the present application provides a method for manufacturing a battery cell, comprising:

[0166] S100, providing a housing, wherein an end of the housing along a first direction has an opening, the housing comprises a first side plate, the first side plate comprises a first plate portion and a second plate portion arranged along the first direction, the second plate portion is located on a side of the first plate portion close to the opening, and the thickness of the second plate portion is greater than the thickness of the first plate portion;

[0167] S200, providing an electrode assembly and an end cap, wherein the electrode assembly includes a main body and an electrode ear connected to the main body;

[0168] S300, installing the electrode assembly into the housing;

[0169] S400, close the end cover to the opening, weld the second plate portion and the end cover to form a welding portion; wherein, in the first direction, one end of the second plate portion close to the first plate portion extends beyond the welding portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap.

[0170] It should be noted that the relevant structure of the battery cell manufactured by the above-mentioned method for manufacturing the battery cell can refer to the battery cell provided in the above-mentioned embodiments.

[0171] When manufacturing a battery assembly based on the above-mentioned method for manufacturing a battery cell, it is not necessary to perform the above-mentioned steps in sequence, that is, the steps can be performed in the order mentioned in the embodiment, or in a different order from the order mentioned in the embodiment, or several steps can be performed simultaneously. For example, the execution of steps S100 and S200 is not in order, and can also be performed simultaneously.

[0172] Fig.16 A schematic block diagram of a manufacturing system for an electrode assembly provided in some embodiments of the present application.

[0173] like Fig.16 As shown, the manufacturing system 90 of the battery cell of the embodiment of the present application includes a first providing device 91, a second providing device 92, a first assembling device 93 and a second assembling device 94. The first providing device 91 is used to provide a shell, the end of the shell along the first direction has an opening, the shell includes a first side plate, the first side plate includes a first plate portion and a second plate portion arranged along the first direction, the second plate portion is located on the side of the first plate portion close to the opening, and the thickness of the second plate portion is greater than the thickness of the first plate portion. The second providing device 92 is used to provide an electrode assembly and an end cap, the electrode assembly includes a main body and a pole ear connected to the main body. The first assembling device 93 is used to install the electrode assembly into the shell. The second assembling device 94 is used to cover the end cap on the opening, weld the second plate portion and the end cap and form a welding portion; wherein, in the first direction, one end of the second plate portion close to the first plate portion exceeds the welding portion; in the thickness direction of the first side plate, the main body and the second plate portion do not overlap.

[0174] The relevant structure of the battery cells manufactured by the above manufacturing system can refer to the battery cells provided in the above embodiments.

[0175] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0176] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein, but these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, comprising: A housing having an opening at an end along a first direction; An electrode assembly is contained in the housing, and includes a main body and a tab connected to the main body; as well as An end cover, used to cover the opening; Wherein, the shell includes a first side plate, the first side plate includes a first plate portion and a second plate portion arranged along the first direction, the second plate portion is located on a side of the first plate portion close to the opening, and the thickness of the second plate portion is greater than the thickness of the first plate portion; The second plate portion is used to be welded with the end cover to form a welding portion; in the first direction, one end of the second plate portion close to the first plate portion exceeds the welding portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap.

2. The battery cell according to claim 1, wherein: The second plate portion protrudes from an inner surface of the first plate portion.

3. The battery cell according to claim 1 or 2, further comprising an insulating member, the insulating member being disposed between the end cover and the main body and abutting against the main body; In the first direction, one end of the second plate portion close to the first plate portion does not extend beyond the surface of the insulating member that abuts against the main body portion.

4. The battery cell according to any one of claims 1 to 3, wherein: The outer surface of the first plate portion is flush with the outer surface of the second plate portion.

5. The battery cell according to any one of claims 1 to 3, wherein: The second plate portion protrudes from an outer surface of the first plate portion.

6. The battery cell according to any one of claims 1 to 5, wherein: The second plate portion includes a base portion and a first transition portion, wherein the first transition portion is connected between the base portion and the first plate portion; and a thickness of the first transition portion gradually decreases in a direction away from the base portion.

7. The battery cell according to any one of claims 1 to 6, wherein: A ratio of a size of the second plate portion along a second direction to a size of the first plate portion along the second direction is 0.3-1, and the second direction is perpendicular to the first direction and the thickness direction.

8. The battery cell according to any one of claims 1 to 7, wherein: The second plate portion is connected to at least a middle region of the first plate portion along a second direction, and the second direction is perpendicular to the first direction and the thickness direction.

9. The battery cell according to claim 8, wherein: The second plate portion is continuously arranged in the second direction, and an edge of the second plate portion along the second direction is flush with an edge of the first plate portion along the second direction.

10. The battery cell according to claim 8 or 9, wherein: The second plate portion includes a base portion and two second transition portions, wherein the two second transition portions are respectively located at two ends of the base portion along the second direction; and the thickness of the second transition portion gradually decreases along a direction away from the base portion.

11. The battery cell according to any one of claims 1 to 10, wherein: The housing includes two first side plates arranged opposite to each other along the thickness direction and two second side plates arranged opposite to each other along the second direction. The first direction, the second direction and the thickness direction are perpendicular to each other.

12. The battery cell according to claim 11, wherein: The shell is in a rectangular parallelepiped shape, and the area of ​​the first side plate is larger than the area of ​​the second side plate.

13. The battery cell according to claim 11 or 12, wherein: The second side plate is provided with a recessed portion, which is recessed from an end surface of the second side plate along the first direction; a portion of the end cover is accommodated in the recessed portion and abuts against a bottom surface of the recessed portion.

14. The battery cell according to claim 13, wherein: The thickness of a portion of the second side plate corresponding to the side surface of the recessed portion is greater than the thickness of the first plate portion.

15. The battery cell according to claim 13 or 14, wherein: In the first direction, one end of the second plate portion close to the first plate portion exceeds the bottom surface of the recessed portion.

16. The battery cell according to any one of claims 11 to 15, wherein: The shell further includes an arc-shaped transition plate, and the transition plate connects the adjacent first side plate and the second side plate.

17. The battery cell according to claim 16, wherein: The transition plate is provided with a first recessed portion, and the first recessed portion is recessed from an end surface of the transition plate along the first direction.

18. The battery cell according to claim 17, wherein: The second side plate is provided with a recessed portion, the recessed portion being recessed from the end surface of the second side plate along the first direction; a portion of the end cover is accommodated in the recessed portion and abuts against the bottom surface of the recessed portion; The first recessed portion of the transition plate is in communication with the recessed portion of the second side plate.

19. The battery cell according to any one of claims 1 to 18, wherein: The electrode assembly is a wound structure and includes a straight region, and the electrode sheet of the electrode assembly includes a plurality of straight portions located in the straight region, and the plurality of straight portions are stacked along the thickness direction; or The electrode assembly includes a plurality of pole pieces, and the plurality of pole pieces are stacked along the thickness direction.

20. The battery cell according to any one of claims 1 to 19, wherein: In the first direction, a ratio of a size of the welding portion to a total size of the second plate portion is 0.1-0.

5.

21. The battery cell according to any one of claims 1 to 20, wherein: In the first direction, the size L1 of the welding portion is 0.5 mm-2 mm; and / or In the first direction, the total dimension L2 of the second plate portion is 3 mm-8 mm.

22. The battery cell according to any one of claims 1 to 21, wherein: The ratio of the thickness of the second plate portion to the thickness of the first plate portion is 1.05-3.

23. The battery cell according to any one of claims 1 to 22, wherein: The thickness of the first plate portion is 0.4 mm-0.6 mm.

24. The battery cell according to any one of claims 1 to 23, wherein: Both ends of the shell along the first direction have the openings; The end covers are provided in two pieces, and the two end covers respectively cover the two openings of the shell; The first side plate includes two second plate portions, and the two second plate portions are respectively arranged on both sides of the first plate portion along the first direction; The two end covers are welded to the two second plate parts respectively.

25. A battery comprising a plurality of battery cells according to any one of claims 1 to 24.

26. An electrical device comprising the battery cell according to any one of claims 1 to 24, wherein the battery cell is used to provide electrical energy.

27. A method for manufacturing a battery cell, comprising: A shell is provided, wherein an end of the shell along a first direction has an opening, the shell comprises a first side plate, the first side plate comprises a first plate portion and a second plate portion arranged along the first direction, the second plate portion is located on a side of the first plate portion close to the opening, and the thickness of the second plate portion is greater than the thickness of the first plate portion; Providing an electrode assembly and an end cap, wherein the electrode assembly includes a main body and a tab connected to the main body; installing the electrode assembly into the housing; Covering the end cover with the opening, welding the second plate portion and the end cover to form a welding portion; Wherein, in the first direction, one end of the second plate portion close to the first plate portion exceeds the welding portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap.

28. A battery cell manufacturing system, comprising: A first providing device is used to provide a shell, wherein the end of the shell along the first direction has an opening, and the shell comprises a first side plate, wherein the first side plate comprises a first plate portion and a second plate portion arranged along the first direction, wherein the second plate portion is located on a side of the first plate portion close to the opening, and the thickness of the second plate portion is greater than the thickness of the first plate portion; A second providing device is used to provide an electrode assembly and an end cap, wherein the electrode assembly includes a main body and a tab connected to the main body; a first assembling device, for installing the electrode assembly into the housing; A second assembling device, used for covering the end cover with the opening, welding the second plate portion and the end cover to form a welded portion; Wherein, in the first direction, one end of the second plate portion close to the first plate portion exceeds the welding portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap.

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