Battery cells and their manufacturing methods and systems, batteries and electrical devices

Abstract

This application provides a battery cell, its manufacturing method and system, a battery, and an electrical device. The battery cell includes a housing, an electrode assembly, and an end cap. The housing has an opening at its end along a first direction. The electrode assembly is housed within the housing and includes a main body and tabs connected to the main body. The end cap is used to close the opening. The housing includes a first side plate, which includes a first plate portion and a second plate portion disposed along the first direction. The second plate portion is located on the side of the first plate portion near 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 to the end cap to form a weld portion; in the first direction, the end of the second plate portion near the first plate portion extends beyond the weld portion; in the thickness direction of the first side plate, the main body and the second plate portion do not overlap. This application embodiment can ensure the strength of the first side plate in the area near the weld portion, reduce the risk of cracking of the first side plate, and improve safety.

Description

[0001] This application is a divisional application based on application number 202280001782.3, filed on January 14, 2022, by CATL (Contemporary Amperex Technology Co., Limited), entitled "Battery cell and manufacturing method and system thereof, battery and electrical device". Technical Field

[0002] This application relates to the field of battery technology, and more specifically, to a battery cell and its manufacturing method and system, a battery, and an electrical device. Background Technology

[0003] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools. Battery cells can include nickel-cadmium battery cells, nickel-metal hydride battery cells, lithium-ion battery cells, and rechargeable alkaline zinc-manganese battery cells, among others.

[0004] In the development of battery technology, besides improving the performance of individual battery cells, safety is also a crucial issue. If the safety of a battery cell cannot be guaranteed, then that cell cannot be used. Therefore, how to enhance the safety of individual battery cells is a pressing technical problem that needs to be solved in battery technology. Summary of the Invention

[0005] This application provides a battery cell, a method and system for manufacturing the same, a battery, and an electrical device that can enhance the safety of the battery cell.

[0006] In a first aspect, embodiments of this application provide a battery cell, including a housing, an electrode assembly, and an end cap. The housing has an opening at its end along a first direction. The electrode assembly is housed within the housing and includes a main body and tabs connected to the main body. The end cap is used to close the opening. The housing includes a first side plate, which includes a first plate portion and a second plate portion disposed along the first direction. The second plate portion is located on the side of the first plate portion near 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 to the end cap to form a weld portion; in the first direction, the end of the second plate portion near the first plate portion extends beyond the weld portion; in the thickness direction of the first side plate, the main body and the second plate portion do not overlap.

[0007] This application increases the thickness of the second plate portion near the opening and extends the end of the second plate portion near the first plate portion beyond the weld portion to ensure the strength of the first side plate in the area near the weld portion, 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 reduces 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 is constant, the second plate protrudes from the inner surface of the first plate, which can reduce the size of the second plate protruding from the outer surface of the first plate, thereby reducing the maximum size of the casing, making full use of the internal space of the casing, and improving the energy density of the battery cell.

[0010] In some embodiments, the battery cell further includes an insulating member disposed between the end cap and the main body and abutting against the main body. In a first direction, the end of the second plate near the first plate does not extend beyond the surface of the insulating member abutting against the main body.

[0011] In the above embodiments, the insulating member can insulate and isolate the end cap and the main body, thereby reducing the risk of the end cap conducting electricity to the positive and negative electrode plates in the main body and improving safety. The insulating member abuts against the main body along the first direction to reduce the amplitude of the main body's sway when the battery cell vibrates, reducing the risk of misalignment of the positive and negative electrode plates and improving 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, reducing the risk of the second plate cracking.

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

[0013] The above-described embodiments can ensure the flatness of the outer surface of the first side plate and improve the appearance of the housing.

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

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

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

[0017] During the charging process of the electrode assembly, the main body expands and compresses the first plate; during the discharging process of the electrode assembly, the main body contracts. Therefore, the expansion and contraction of the main body causes the first side plate to oscillate back and forth around the weld point. The main body expands significantly in the middle along the second direction, resulting in a larger oscillation amplitude in the middle region of the first side plate along the second direction. Consequently, the area of ​​the first side plate located in the middle along the second direction and close to the weld point is prone to cracking under the combined effects of thermal stress and oscillation stress. In the above embodiment, the second plate is at least connected to the middle region of the first plate along the second direction. This strengthens the area of ​​the first side plate under greater stress, reducing the risk of cracking.

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

[0019] In the above embodiment, the end of the first side plate near 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, which are located at opposite ends of the base portion along a second direction; the thickness of the second transition portions gradually decreases along the direction away from the base portion.

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

[0022] In some embodiments, the housing includes two first side plates disposed opposite each other along a thickness direction and two second side plates disposed opposite each other along a second direction, the first direction, the second direction, and the thickness direction being perpendicular to each other. The second side plates have recesses that are recessed from the end face of the second side plate along the first direction; a portion of the end cap is received in the recess and abuts against the bottom surface of the recess. The thickness of the portion of the second side plate corresponding to the side face of the recess 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 cap and limit its movement as it extends into the housing, preventing it from extending excessively into the housing. The portion of the second side plate corresponding to the side of the recess can be welded to the end cap. Even though this embodiment has a recess on the second side plate, the strength of the portion of the second side plate corresponding to the side of the recess can be guaranteed, reducing the risk of cracking of the second side plate.

[0024] In some embodiments, in the first direction, the end of the second plate portion near the first plate portion extends beyond the bottom surface of the recess.

[0025] The bottom surface of the recess is used to support the end cap, so the bottom surface of the recess also restricts the position of the end cap. In the above embodiment, the end of the second plate near the first plate extends beyond the bottom surface of the recess. This allows the end of the second plate near the first plate to extend beyond the end cap and the weld, thereby ensuring the strength of the first side plate in the area near the weld, 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 flat region. The electrode sheet of the electrode assembly includes a plurality of flat portions located in the flat region, and the plurality of flat portions are stacked along the thickness direction.

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

[0028] In some embodiments, the electrode assembly includes multiple electrodes stacked along the thickness direction.

[0029] In the above embodiment, the expansion of the electrode assembly along the stacking direction of the multiple electrode sheets is the greatest, so the first side plate is subjected to a large force; the above embodiment increases the thickness of the second plate to reduce the risk of cracking of the first side plate.

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

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

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

[0033] When the thickness of the first plate is constant, the greater the thickness of the second plate, the higher its strength and the less prone it is to cracking. However, a greater thickness of the second plate also means a larger space it occupies, a heavier casing, and a lower energy density for the individual battery cells. The above embodiment limits the thickness ratio of the second plate to the first plate to 1.05-3 to balance the strength of the second plate and the energy density of the individual battery cells.

[0034] Secondly, embodiments of this application provide a battery comprising a plurality of battery cells according to any of the embodiments of the first aspect.

[0035] Thirdly, embodiments of this application provide an electrical device including a battery cell according to any of the embodiments of the first aspect, wherein the battery cell is used to provide electrical energy.

[0036] Fourthly, embodiments of this application provide a method for manufacturing a single battery cell, comprising:

[0037] A housing is provided, the housing having an opening at one end along a first direction, the housing including a first side plate, the first side plate including a first plate portion and a second plate portion disposed along the first direction, the second plate portion being located on the side of the first plate portion near the opening, and the thickness of the second plate portion being greater than the thickness of the first plate portion;

[0038] An electrode assembly and an end cap are provided. The electrode assembly includes a main body and a tab connected to the main body.

[0039] Install the electrode assembly into the housing;

[0040] Close the end cap to the opening, weld the second plate and the end cap together to form a welded part;

[0041] In the first direction, the end of the second plate portion near 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.

[0042] Fifthly, embodiments of this application provide a battery cell manufacturing system, including a first providing device, a second providing device, a first assembly device, and a second assembly device. The first providing device provides a housing, the housing having an opening at one end along a first direction. The housing includes a first side plate, the first side plate including a first plate portion and a second plate portion disposed along the first direction, the second plate portion being located on the side of the first plate portion near the opening, and the thickness of the second plate portion being greater than the thickness of the first plate portion. The second providing device provides an electrode assembly and an end cap, the electrode assembly including a main body portion and a tab connected to the main body portion. The first assembly device is used to install the electrode assembly into the housing. The second assembly device is used to close the end cap to the opening, weld the second plate portion and the end cap to form a welded portion. In the first direction, the end of the second plate portion near the first plate portion extends beyond the welded portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0044] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0045] Figure 2 Explosion diagrams of batteries provided for some embodiments of this application;

[0046] Figure 3 for Figure 2 The diagram shows the structure of the battery module.

[0047] Figure 4 This is an exploded schematic diagram of a battery cell provided in some embodiments of this application;

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

[0049] Figure 6 for Figure 5 The diagram shows a cross-sectional view of a single battery cell along the AA direction.

[0050] Figure 7 for Figure 6 The enlarged schematic diagram of the battery cell shown at point C in the circle;

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

[0052] Figure 9 for Figure 5 The diagram shows a cross-sectional view of a single battery cell along the BB direction.

[0053] Figure 10 for Figure 9 The enlarged schematic diagram of the battery cell shown at point D in the circle;

[0054] Figure 11 This is a schematic diagram of the structure of the casing of a battery cell provided in some embodiments of this application;

[0055] Figure 12 for Figure 11 The enlarged schematic diagram of the shell at point E in the circular frame is shown;

[0056] Figure 13 This is a schematic diagram of the structure of the electrode assembly of a battery cell provided in some embodiments of this application;

[0057] Figure 14 A schematic diagram of the electrode assembly of a battery cell provided in other embodiments of this application;

[0058] Figure 15A schematic flowchart illustrating a method for manufacturing a single battery cell according to some embodiments of this application;

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

[0060] The accompanying drawings are not drawn to scale. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort 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 meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

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

[0064] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0065] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0066] In the embodiments of this application, the same reference numerals denote 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 this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0067] In this application, "multiple" means two or more (including two).

[0068] In this application, the term "parallel" includes not only the case of absolute parallelism, but also the case of approximate parallelism as commonly understood in engineering; similarly, "perpendicular" includes not only the case of absolute perpendicularity, but also the case of approximate perpendicularity as commonly understood in engineering.

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

[0070] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may be a battery module or a battery pack. A battery generally includes a housing for encapsulating one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

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

[0072] The battery cell also includes a housing and an end cap. The housing has an opening, and the end cap closes to the opening and seals the connection to form a sealed space for accommodating the electrode assembly and electrolyte.

[0073] In related technologies, the housing and end caps are connected by welding. Welding ensures both the connection strength between the housing and end caps and achieves a seal between them.

[0074] The inventors discovered that after welding, a heat-affected zone (HAZ) forms near the molten pool in the casing. This HAZ is subjected to residual thermal stress, resulting in lower strength compared to other areas. When the HAZ is subjected to pressure during battery cell use, the casing may crack in the HAZ, leading to electrolyte leakage, battery cell failure, and safety risks.

[0075] In view of this, this application provides a battery cell including a housing, an electrode assembly, and an end cap. The housing has an opening at its end along a first direction. The electrode assembly is housed within the housing and includes a main body and tabs connected to the main body. The end cap is used to close the opening. The housing includes a first side plate, which includes a first plate portion and a second plate portion disposed along the first direction. The second plate portion is located on the side of the first plate portion near 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 to the end cap to form a weld portion. In the first direction, the end of the second plate portion near the first plate portion extends beyond the weld portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap. This embodiment increases the thickness of the second plate portion near the opening to ensure the strength of the first side plate in the area near the weld portion, thereby reducing the risk of cracking of the first side plate and improving safety. The main body portion and the second plate portion do not overlap in the thickness direction of the first side plate, which reduces the risk of the main body portion directly colliding with or squeezing the second plate portion, thereby reducing the risk of cracking of the second plate portion.

[0076] The battery cells described in the embodiments of this application are applicable to batteries and electrical devices that use batteries.

[0077] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0078] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0079] Figure 1 The diagram shows the structure of a vehicle provided in some embodiments of this application.

[0080] like Figure 1 As shown, a battery 2 is installed inside the vehicle 1. The battery 2 can be located at the bottom, front, or rear of the vehicle 1. The battery 2 can be used to power the vehicle 1; for example, the battery 2 can serve as the operating power source for the vehicle 1.

[0081] Vehicle 1 may also include controller 3 and motor 4. Controller 3 is used to control battery 2 to supply power to motor 4, for example, for the power needs of vehicle 1 during start-up, navigation and driving.

[0082] In some embodiments of this application, the battery 2 can not only serve as the operating power source for the vehicle 1, but also as the 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 This is an exploded schematic diagram of a battery provided for some embodiments of this application.

[0084] like Figure 2 As shown, battery 2 includes a housing 5 and battery cells ( Figure 2 (Not shown), the battery cells are housed inside the casing 5.

[0085] The housing 5 is used to house individual battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the individual battery cells. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as cylinders, cuboids, etc.

[0086] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

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

[0088] In battery 2, there can be one or more individual battery cells. If there are multiple individual battery cells, they can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple individual battery cells are connected in both series and parallel configurations. Multiple individual battery cells can be directly connected in series, parallel, or in a mixed configuration and then housed within housing 5. Alternatively, multiple individual battery cells can first be connected in series, parallel, or in a mixed configuration to form battery module 6, and then multiple battery modules 6 can be connected in series, parallel, or in a mixed configuration to form a whole and housed within housing 5.

[0089] Figure 3 for Figure 2 The diagram shows the structure of the battery module.

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

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

[0092] Figure 4 This is an exploded schematic diagram of a battery cell provided in some embodiments of this application; Figure 5 A top view schematic diagram of a battery cell provided in some embodiments of this application; Figure 6 for Figure 5 The diagram shows a cross-sectional view of a single battery cell along the AA direction. Figure 7 for Figure 6 The diagram shows an enlarged view of the battery cell at point C in the circle.

[0093] like Figures 4 to 7 As shown, this application embodiment provides a battery cell 7, which includes a housing 20, an electrode assembly 10, and an end cap 30. The housing 20 has an opening 20a at its end along a first direction X. The electrode assembly 10 is housed within the housing 20 and includes a main body 11 and tabs 12 connected to the main body 11. The end cap 30 is used to cover the opening 20a. The housing 20 includes a first side plate 21, which includes a first plate portion 211 and a second plate portion 212 disposed along the first direction X. The second plate portion 212 is located on the side of the first plate portion 211 near 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 to the end cap 30 to form a weld portion W; in the first direction X, the end of the second plate portion 212 near the first plate portion 211 extends beyond the weld 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 housing 20 is a hollow structure, with an internal cavity for accommodating the electrode assembly 10 and the electrolyte. The housing 20 can be of various shapes, such as a cylinder or a cuboid. The shape of the housing 20 can be determined based on the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a cylindrical structure, a cylindrical housing can be used; if the electrode assembly 10 is a cuboid structure, a cuboid housing can be used.

[0095] The end cap 30 is sealed 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 simultaneously achieves both sealing and securing 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 an end cap 30 is provided to cover the opening 20a of the housing 20. In other examples, the housing 20 has openings 20a at both ends along the first direction X, and two end caps 30 are provided, with the two end caps 30 respectively covering the two openings 20a of the housing 20.

[0097] For example, the first direction X is parallel to the thickness direction of the end cap 30.

[0098] The electrode assembly 10 is the core component for enabling the charging and discharging function of the battery cell 7. It includes a first electrode, a second electrode, and a separator. The first and second electrodes have opposite polarities, and the separator is used to insulate and isolate the first and second electrodes. The electrode assembly 10 mainly relies on the movement of metal ions between the first and second electrodes to operate.

[0099] One of the first and second electrodes is the positive electrode, and the other of the first and second electrodes is the negative electrode.

[0100] The electrode assembly 10 can be a wound structure, a stacked structure, or other structures. There can be one or more first electrodes and one or more second electrodes. The number of first electrodes and second electrodes can be determined according to the structure of the electrode assembly 10.

[0101] The electrode assembly 10 can be one or more, and this embodiment does not limit this.

[0102] The main body 11 is the electrogenerating part of the electrode assembly 10, and the active material inside it is used to undergo an electrochemical reaction with the electrolyte to generate a charging and discharging process. The tab 12 extends from the end of the main body 11 and is used to conduct electrical energy generated by the main body 11.

[0103] The main body 11 includes a positive current collector, a positive active material layer, a negative current collector, a negative active material layer, and an insulating component. The tab 12 includes a positive tab and a negative tab.

[0104] For example, the first side plate 21 is generally a plate-like structure parallel to the first direction X.

[0105] The housing 20 may include one or more first side plates 21. For example, for a cuboid housing 20, there may be two first side plates 21, which are arranged opposite to each other. For a cylindrical housing 20, there may be one first side plate 21, which is generally cylindrical in structure.

[0106] The second plate portion 212 can be disposed on one side of the first plate portion 211 along the first direction X, or it can 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, a second plate portion 212 is disposed on one side of the first plate portion 211 along the first direction X, and an end cap 30 is provided and welded to the second plate portion 212. In other examples, the housing 20 has openings 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, and two end caps 30 are provided, with the two end caps 30 respectively welded to the two second plate portions 212.

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

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

[0110] In a direction parallel to the first direction X and gradually approaching the first plate portion 211, the second plate portion 212 extends beyond the welding portion W.

[0111] After the weld portion W is formed, residual thermal stress will remain in the area of ​​the second plate portion 212 near the weld portion W. This embodiment increases the thickness of the second plate portion 212 near the opening 20a and extends one end of the second plate portion 212 near the first plate portion 211 beyond the weld portion W to ensure the strength of the first side plate 21 in the area near the weld portion W, reducing the risk of cracking of the first side plate 21 and improving safety. The main body portion 11 and the second plate portion 212 do not overlap in the thickness direction Y of the first side plate 21. This reduces the risk of the main body portion 11 directly colliding with or pressing against the second plate portion 212, further reducing the risk of cracking of the second plate portion 212 and improving safety.

[0112] This embodiment only increases the thickness of the second plate 212. 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 casing 20 and increase 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 cap 30, the two electrode terminals 40 being used to electrically connect with the first electrode and the second electrode, respectively, to conduct 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 protruding from the inner surface of the first plate portion 211 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 the surface of the first plate portion 211 facing the electrode assembly 10, and the outer surface of the first plate portion 211 is the 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 212 do not overlap in the thickness direction Y of the first side plate 21. This reduces the risk of the portion of the second plate 212 protruding from the inner surface of the first plate 211 pressing against the main body 11, reduces the stress on the main body 11, and improves 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 cap 30 and the main body portion 11 and abuts against the main body portion 11. In the first direction X, the end of the second plate portion 212 near the first plate portion 211 does not extend beyond the surface of the insulating member 50 that abuts against the main body portion 11.

[0120] In this embodiment, the insulating member 50 can insulate and isolate the end cap 30 and the main body 11, thereby reducing the risk that the end cap 30 will conduct the positive and negative electrode plates in the main body 11, and improving safety. The insulating member 50 abuts against the main body 11 along the first direction X, so as 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 electrode plates, and improve the charging and discharging performance of the electrode assembly 10. The insulating member 50 can limit the position of the main body 11 along the first direction X, thereby reducing the possibility that the main body 11 will collide with the second plate 212 when the battery cell 7 vibrates, and reducing the risk of cracking of the second plate 212.

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

[0122] The base portion 212a is used to weld with the end cap 30 to form a weld portion W.

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

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

[0125] The thickness of the end of the first transition portion 212b connected to the base portion 212a is equal to the thickness of the base portion 212a, and the thickness of the end of the first transition portion 212b 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, the ratio of the dimension L1 of the welded portion W to the total 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, connection failure is likely to occur between the end cap 30 and the second plate portion 212. The larger the value of L1 / L2, the smaller the distance between the welded part W and the first plate portion 211; if the value of L1 / L2 is too large, the thermal stress generated by welding may be transmitted to the first plate portion 211, thereby increasing the risk of cracking of the first plate portion 211. Through 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, as well as the strength of the first plate portion 211.

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

[0129] In some embodiments, the thickness ratio of the second plate portion 212 to 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 prone it is to cracking. However, a greater thickness of the second plate portion 212 also means a larger space occupied by it, a heavier casing 20, and a lower energy density of the battery cell 7. In this embodiment, the thickness ratio 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 212a can be used as the thickness of the second plate portion 212.

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

[0133] Figure 8 This is a top view schematic diagram of the casing of a battery cell provided in some embodiments of this application.

[0134] like Figure 7 and Figure 8 As shown, in some embodiments, the second plate portion 212 is at least connected to the middle region of the first plate portion 211 along the second direction Z, which 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 expands and compresses the first plate 211; during the discharging process of the electrode assembly 10, the main body 11 contracts. Therefore, the expansion and contraction of the main body 11 causes the first side plate 21 to oscillate back and forth around the welded part W. The expansion of the main body 11 in the middle along the second direction Z is relatively large, and the oscillation amplitude of the first side plate 21 in the middle region along the second direction Z is also relatively large. Therefore, the region of the first side plate 21 located in the middle along the second direction Z and close to the welded part W is prone to cracking under the combined action of thermal stress and oscillation 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. This can strengthen the area of ​​the first side plate 21 that is subjected to greater stress, thereby reducing the risk of cracking of the first side plate 21.

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

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

[0139] In some embodiments, the second plate portion 212 is continuously disposed 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 of the first side plate 21 near 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 both ends of the base portion 212a along the second direction Z. The thickness of the second transition portions 212c gradually decreases along the direction away from the base portion 212a.

[0142] By providing a second transition portion 212c, this embodiment can achieve a smooth transition at the junction of the second plate portion 212 and other parts of the housing 20 (such as the second side plate described later), reducing stress concentration and lowering the risk of cracking of the first side plate 21.

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

[0144] Figure 9 for Figure 5 The diagram shows a cross-sectional view of a single battery cell along the BB direction. Figure 10 for Figure 9 The enlarged schematic diagram of the battery cell shown at point D in the circle; Figure 11 This is a schematic diagram of the structure of the casing of a battery cell provided in some embodiments of this application; Figure 12 for Figure 11 The enlarged schematic diagram of the shell shown at point E in the circular frame.

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

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

[0147] For example, the bottom surface of the recess 221 may be a plane. The included 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 cap 30 and limit the end cap 30 as it extends into the housing 20, preventing it from extending excessively into the housing 20. The portion of the second side plate 22 corresponding to the side surface of the recess 221 can be welded to the end cap 30. Even though 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 surface of the recess 221 can be guaranteed, 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, which connects adjacent first side plates 21 and second side plates 22.

[0150] In some embodiments, the transition plate 23 is also provided with a recess, which is recessed from the end face of the transition plate 23 along the first direction X. Exemplarily, the recess of the transition plate 23 communicates with the recess 221 of the second side plate 22.

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

[0152] The bottom surface of the recess 221 is used to support the end cap 30, so the bottom surface of the recess 221 also restricts the position of the end cap 30. In this embodiment, the end of the second plate portion 212 near the first plate portion 211 extends beyond the bottom surface of the recess 221. This allows the end of the second plate portion 212 near the first plate portion 211 to extend beyond the end cap 30 and the weld portion W, thereby ensuring the strength of the first side plate 21 in the area near the weld portion W, reducing the risk of cracking of the first side plate 21, and improving safety.

[0153] Figure 13 This is a schematic diagram of the structure of the electrode assembly of a battery cell provided in some embodiments of this application.

[0154] like Figure 13 As shown, in some embodiments, the electrode assembly 10 has a wound structure and includes a flat region 10a. The electrode assembly 10 includes an electrode sheet 13, which includes a plurality of flat portions 131 located in the flat region 10a, and the plurality of flat portions 131 are stacked along the thickness direction Y.

[0155] The flat region 10a is the area of ​​the electrode assembly 10 with a flat structure, and the portion of the electrode 13 located in the flat region 10a (i.e., the flat portion 131) is substantially flat. Multiple flat portions 131 are stacked along the thickness direction Y. Exemplarily, the flat portion 131 is generally flat.

[0156] During the charging process of the electrode assembly 10, the electrode sheet 13 expands along its thickness direction Y. In the wound electrode assembly 10, the expansion of the electrode assembly 10 along the stacking direction of the straight portion 131 is the greatest, so the first side plate is subjected to a large force; in this embodiment, the thickness of the second plate portion is increased 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 13 further includes a bent portion 132 located in the bending region 10b. The bending region 10b is the area of ​​the electrode assembly 10 with a bent structure, and the portion of the electrode 13 located in the bending region 10b (i.e., the bent portion 132) is bent. Exemplarily, the bent portion 132 is generally bent into an arc shape.

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

[0159] Figure 14 This is a schematic diagram of the structure of the electrode assembly of a battery cell provided in some other embodiments of this application.

[0160] like Figure 14 As shown, in some embodiments, the electrode assembly 10 includes a plurality of electrode sheets 13, which are stacked along the thickness direction Y.

[0161] During the charging process of the electrode assembly 10, the electrode 13 expands along its thickness direction Y. In this embodiment, the expansion of the electrode assembly 10 along the stacking direction of the plurality of electrode 13 is the greatest, so the first side plate is subjected to a larger force; the embodiment of this application increases the thickness of the second plate 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 plates and a plurality of negative electrode plates, which are stacked alternately.

[0163] In other embodiments, the electrode assembly 10 includes a plurality of positive electrode plates and a negative electrode plate, the negative electrode plate being continuously bent to form a plurality of negative electrode stacked segments, and the plurality of negative electrode stacked segments and the plurality of positive electrode plates being stacked alternately.

[0164] Figure 15 This is a schematic flowchart illustrating a method for manufacturing a battery cell according to some embodiments of this application.

[0165] like Figure 15 As shown in the figure, this application provides a method for manufacturing a single battery cell, including:

[0166] S100. A housing is provided, the housing having an opening at its end along a first direction, the housing including a first side plate, the first side plate including a first plate portion and a second plate portion disposed along the first direction, the second plate portion being located on the side of the first plate portion near the opening, and the thickness of the second plate portion being greater than the thickness of the first plate portion.

[0167] S200, providing an electrode assembly and an end cap, the electrode assembly including a main body and an electrode tab connected to the main body;

[0168] S300. Install the electrode assembly into the housing;

[0169] S400, the end cap is closed to the opening, and the second plate portion and the end cap are welded to form a welded portion; wherein, in the first direction, the end of the second plate portion near the first plate portion extends beyond the welded 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-described battery cell manufacturing method can be found in the battery cells provided in the above embodiments.

[0171] When manufacturing battery modules based on the above-described method for manufacturing individual battery cells, the steps do not necessarily need to be performed sequentially. That is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously. For example, steps S100 and S200 can be performed in any order and can be performed simultaneously.

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

[0173] like Figure 16 As shown, the battery cell manufacturing system 90 of this application embodiment includes a first providing device 91, a second providing device 92, a first assembly device 93, and a second assembly device 94. The first providing device 91 provides a housing with an opening at one end along a first direction. The housing includes a first side plate, which includes a first plate portion and a second plate portion disposed along the first direction. The second plate portion is located on the side of the first plate portion near 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 provides an electrode assembly and an end cap. The electrode assembly includes a main body portion and a tab connected to the main body portion. The first assembly device 93 installs the electrode assembly into the housing. The second assembly device 94 closes the end cap to the opening, welds the second plate portion and the end cap to form a welded portion; wherein, in the first direction, the end of the second plate portion near the first plate portion extends beyond the welded portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap.

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

[0175] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0176] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features. However, these modifications or substitutions 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 this application.

Claims

1. A single battery cell, comprising: The housing has an opening at one end along a first direction; An electrode assembly is housed within the housing, the electrode assembly comprising a main body and tabs connected to the main body; as well as End cap, used to cover the opening; The housing includes two first side plates and two second side plates. The two first side plates are arranged opposite each other along the thickness direction of the first side plates, and the two second side plates are arranged opposite each other along a second direction. The first direction, the second direction and the thickness direction are perpendicular to each other. The first side plate includes a first plate portion and a second plate portion disposed along the first direction, the second plate portion being located on the side of the first plate portion near the opening, and the thickness of the second plate portion being greater than the thickness of the first plate portion. The second plate portion is used to weld to the end cap and form a weld portion; in the first direction, one end of the second plate portion near the first plate portion extends beyond the weld portion; in the thickness direction of the first side plate, the main body portion and the second plate portion do not overlap; the second plate portion is at least connected to the middle region of the first plate portion along the second direction, the second plate portion includes a base portion and two second transition portions, the two second transition portions being located at both ends of the base portion along the second direction; the thickness of the second transition portions gradually decreases along the direction away from the base portion; the second side plate is welded to the end cap.

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

3. The battery cell according to claim 1 further includes an insulating member, the insulating member being disposed between the end cap and the main body and abutting against the main body; In the first direction, the end of the second plate portion near 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 of claim 1, wherein, The outer surface of the first plate is flush with the outer surface of the second plate.

5. The battery cell of claim 1, wherein, The second plate protrudes from the outer surface of the first plate.

6. The battery cell according to claim 1, wherein, The second plate portion includes a first transition portion, which connects the base portion and the first plate portion; the thickness of the first transition portion gradually decreases along the direction away from the base portion.

7. The battery cell according to claim 1, wherein, The ratio of the dimension of the second plate portion along the second direction to the dimension 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 claim 1, wherein, The second plate portion is continuously disposed in the second direction, and the edge of the second plate portion along the second direction is flush with the edge of the first plate portion along the second direction.

9. The battery cell according to any one of claims 1-8, wherein, The shell is rectangular, and the area of ​​the first side plate is larger than the area of ​​the second side plate.

10. The battery cell according to any one of claims 1-8, wherein, The second side plate has a recess that is recessed from the end face of the second side plate along the first direction; a portion of the end cap is accommodated in the recess and abuts against the bottom surface of the recess.

11. The battery cell according to claim 10, wherein, The thickness of the portion of the second side plate corresponding to the side of the recess is greater than the thickness of the first plate portion.

12. The battery cell according to claim 10, wherein, In the first direction, one end of the second plate portion near the first plate portion extends beyond the bottom surface of the recess.

13. The battery cell according to any one of claims 1-8, wherein, The housing also includes an arc-shaped transition plate that connects the adjacent first side plate and the second side plate.

14. The battery cell according to claim 13, wherein, The transition plate is provided with a first recess, which is recessed from the end face of the transition plate along the first direction.

15. The battery cell according to claim 14, wherein, The second side plate is provided with a recess, which is recessed from the end face of the second side plate along the first direction; a portion of the end cap is accommodated in the recess and abuts against the bottom surface of the recess; The first recess of the transition plate communicates with the recess of the second side plate.

16. The battery cell according to claim 1, wherein, The electrode assembly has a wound structure and includes a flat region. The electrode sheet of the electrode assembly includes multiple flat portions located in the flat region, and the multiple flat portions are stacked along the thickness direction; or The electrode assembly includes multiple electrode sheets, which are stacked along the thickness direction.

17. The battery cell according to claim 1, wherein, In the first direction, the ratio of the size of the welded portion to the total size of the second plate portion is 0.1-0.

5.

18. The battery cell according to claim 1, wherein, In the first direction, the dimension L1 of the welded portion is 0.5mm-2mm; and / or In the first direction, the total dimension L2 of the second plate portion is 3mm-8mm.

19. The battery cell according to claim 1, wherein, The thickness ratio of the second plate portion to the first plate portion is 1.05-3.

20. The battery cell according to claim 1, wherein, The thickness of the first plate portion is 0.4mm-0.6mm.

21. The battery cell according to claim 1, wherein, The housing has the opening at both ends along the first direction; The end caps are provided in two parts, and the two end caps respectively cover the two openings of the housing; The first side plate includes two second plate portions, which are respectively disposed on both sides of the first plate portion along the first direction; The two end caps are respectively welded to the two second plate portions.

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

23. An electrical device comprising a battery cell according to any one of claims 1-21, the battery cell being used to provide electrical energy.

24. A method for manufacturing a single battery cell, comprising: A housing is provided, the housing having an opening at its end along a first direction, the housing including two first side plates and two second side plates, the two first side plates being disposed opposite each other along the thickness direction of the first side plates, the two second side plates being disposed opposite each other along a second direction, the first direction, the second direction and the thickness direction being perpendicular to each other, the first side plate including a first plate portion and a second plate portion disposed along the first direction, the second plate portion being located on the side of the first plate portion near the opening, and the thickness of the second plate portion being greater than the thickness of the first plate portion; An electrode assembly and an end cap are provided, the electrode assembly including a body portion and tabs connected to the body portion; The electrode assembly is installed into the housing; The end cap is placed over the opening, the second plate portion and the end cap are welded together to form a welded portion, and the second side plate and the end cap are welded together; In the first direction, one end of the second plate portion near the first plate portion extends beyond the weld portion; in the thickness direction of the first side plate, the main body portion does not overlap with the second plate portion; the second plate portion is at least connected to the middle region of the first plate portion along the second direction, the second plate portion includes a base portion and two second transition portions, the two second transition portions are respectively located at both ends of the base portion along the second direction; the thickness of the second transition portions gradually decreases along the direction away from the base portion.

25. A system for manufacturing a single battery cell, comprising: A first providing device is used to provide a housing having an opening at one end along a first direction. The housing includes two first side plates and two second side plates. The two first side plates are disposed opposite each other along the thickness direction of the first side plates, and the two second side plates are disposed opposite each other along a second direction. The first direction, the second direction, and the thickness direction are perpendicular to each other. The first side plate includes a first plate portion and a second plate portion disposed along the first direction. The second plate portion is located on the side of the first plate portion near 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, the electrode assembly including a main body and tabs connected to the main body; A first assembly device is used to install the electrode assembly into the housing; The second assembly device is used to close the end cap to the opening, weld the second plate portion and the end cap to form a welded portion, and weld the second side plate and the end cap. In the first direction, one end of the second plate portion near the first plate portion extends beyond the weld portion; in the thickness direction of the first side plate, the main body portion does not overlap with the second plate portion; the second plate portion is at least connected to the middle region of the first plate portion along the second direction, the second plate portion includes a base portion and two second transition portions, the two second transition portions are respectively located at both ends of the base portion along the second direction; the thickness of the second transition portions gradually decreases along the direction away from the base portion.

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