Battery cell, battery, electrical device and energy storage apparatus

Abstract

Embodiments of the application provides a battery cell, a battery, an electrical device and an energy storage apparatus. The battery cell comprises a housing. The housing comprises a housing body and an end cover. The housing body is provided with an opening. The housing body comprises a first wall, and the first wall comprises a first opening part and a first body part which are sequentially distributed in a first direction. The first direction is parallel to the thickness direction of the end cover. The first body part is away from the opening relative to the first opening part. The thickness of the first opening part is larger than the thickness of the first body part. The end cover is connected to the first wall and seals the opening. The maximum thickness of the first opening part is t1. The thickness of the first body part is t2. The size of the first wall in a second direction is a.The second direction, the thickness direction of the first wall and the and the first direction are mutually perpendicular in pairs. The relation 120≤a / (t1-t2)≤6000 is satisfied. The technical solution provided by the embodiment of the present application can improve the reliability of the battery.

Description

Battery cells, batteries, electrical equipment and energy storage devices Technical Field

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

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry. Electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of the sustainable development of the automotive industry. For electric vehicles, battery technology is a key factor in their development.

[0003] During the manufacturing process of batteries, battery reliability is an issue that cannot be ignored. Therefore, how to improve battery reliability is a technical problem that needs to be solved urgently in battery technology.

[0004] Summary of the Invention

[0005] The present application provides a battery cell, a battery, an electrical device and an energy storage device, which can improve the reliability of the battery.

[0006] This application is achieved through the following technical solutions:

[0007] In a first aspect, embodiments of the present application provide a battery cell, comprising a housing. The housing comprises a shell and an end cap, the shell having an opening, the shell comprising a first wall, the first wall comprising a first opening portion and a first body portion sequentially distributed along a first direction, the first direction being parallel to a thickness direction of the end cap, the first body portion being farther from the opening than the first opening portion, the first opening portion having a thickness greater than that of the first body portion, and the end cap being connected to the first opening portion and sealing the opening; wherein the maximum thickness of the first opening portion is t1, the thickness of the first body portion is t2, the dimension of the first wall in the second direction is a, the second direction, the thickness direction of the first wall, and the first direction are perpendicular to each other, satisfying the condition 120≤a / (t1-t2)≤6000.

[0008] According to the battery cell of the embodiment of the present application, the larger the size of the first wall in the second direction is, the more the strength of the first opening needs to be increased; the above-mentioned relationship is satisfied between the size of the first wall in the second direction and the difference between the maximum thickness of the first opening and the thickness of the first main body. On the one hand, it is convenient for processing and manufacturing, and the first opening can have a higher strength, which can reduce the risk of fatigue cracking of the shell near the welding area of ​​the shell and the end cover, and improve the reliability of the battery cell; on the other hand, the first opening occupies a smaller assembly space, and the battery cell can have a higher energy density.

[0009] According to some embodiments of the present application, 400≤a / (t1-t2)≤3000, optionally, 500≤a / (t1-t2)≤2000.

[0010] In the above solution, compared with 120≤a / (t1-t2)≤6000, when 400≤a / (t1-t2)≤3000, or 500≤a / (t1-t2)≤2000, the processing and manufacturing difficulty is lower, the first opening portion can have higher strength, and the battery cell has higher energy density.

[0011] According to some embodiments of the present application, 70 mm ≤ a ≤ 600 mm.

[0012] In the above solution, the dimension a of the first wall in the second direction satisfies the above relationship, and the battery cell has a larger dimension in the second direction, so that the battery cell can have a higher energy density.

[0013] According to some embodiments of the present application, 100 mm ≤ a ≤ 500 mm.

[0014] In the above solution, compared with 70mm≤a≤600mm, when 100mm≤a≤500mm, the battery cell can have a higher energy density and is easy to process and manufacture.

[0015] According to some embodiments of the present application, the first opening portion includes a first section and a second section connected to each other, the first section, the second section and the first main body portion are distributed in sequence along the first direction, the maximum thickness of the second section is greater than the thickness of the first main body portion, the maximum thickness of the second section is greater than the maximum thickness of the first section, and the end cover is connected to the first section.

[0016] In the above scheme, the first section, the second section and the first main body are distributed in sequence along the first direction, and the end cover is connected to the first section so that the second section is adjacent to the connection part between the end cover and the first section. The maximum thickness of the second section is greater than the thickness of the first main body, and the maximum thickness of the second section is greater than the maximum thickness of the first section, so that the first opening has higher strength, which can reduce the risk of fatigue cracking of the shell near the welding area of ​​the shell and the end cover, and improve the service life and reliability of the battery cell.

[0017] According to some embodiments of the present application, a first step surface is formed between the second section and the first section, and the end cover overlaps the first step surface.

[0018] In the above solution, the end cover overlaps the first step surface, which facilitates the positioning of the end cover.

[0019] According to some embodiments of the present application, the shell further includes a second wall, which is disposed adjacent to the first wall and connected to the end cover, and the area of ​​the outer surface of the first wall is greater than the area of ​​the outer surface of the second wall.

[0020] In the above scheme, the second wall is arranged adjacent to the first wall, and the second wall and the same end of the first wall together form an opening; the area of ​​the outer surface of the first wall is larger than the area of ​​the outer surface of the second wall, and the size of the first wall in the second direction is larger than the size of the second wall in the second direction. The first wall can be the larger surface of the battery cell, and the first opening is thickened to reduce the risk of fatigue cracking of the shell near the welding area of ​​the shell and the end cover.

[0021] According to some embodiments of the present application, the second wall includes a second opening portion and a second body portion distributed sequentially along the first direction, the second body portion is farther away from the opening than the second opening portion, and the maximum thickness of the second opening portion is greater than the thickness of the second body portion.

[0022] In the above solution, the second opening portion is close to the opening, and the second opening portion is thickened, which can improve the strength of the second wall and reduce the risk of cracking of the shell near the welding area between the shell and the end cover when the battery cell has thermal runaway or the gas production is too large.

[0023] According to some embodiments of the present application, a dimension of the second wall in the third direction is b, and the third direction, the second direction, and the first direction are perpendicular to each other, satisfying 40 mm ≤ b.

[0024] In the above solution, the size of the second wall in the third direction satisfies the above relationship, which can improve the strength of the second wall, restrain the expansion and deformation of the second wall, reduce the risk of cracking of the shell near the welding area between the shell and the end cover, and has low processing and manufacturing difficulty.

[0025] According to some embodiments of the present application, the second opening portion includes a third segment and a fourth segment that are connected to each other, and the third segment, the fourth segment and the second main body portion are distributed in sequence along the first direction. The maximum thickness of the fourth segment is greater than the thickness of the second main body portion, and the maximum thickness of the fourth segment is greater than the maximum thickness of the third segment. A second step surface is formed between the fourth segment and the third segment, and the end cover overlaps the second step surface and is connected to the third segment.

[0026] In the above solution, the third section, fourth section, and second body portion are sequentially arranged along the first direction, and the end cap is connected to the third section so that the fourth section is adjacent to the connection between the end cap and the third section. The maximum thickness of the fourth section is greater than the thickness of the second body portion, and the maximum thickness of the fourth section is greater than the maximum thickness of the third section. This provides the second opening with high strength, reduces the risk of cracking of the housing near the weld area between the housing and the end cap, and improves the service life and reliability of the battery cell. The end cap overlaps the second step surface to facilitate positioning of the end cap.

[0027] According to some embodiments of the present application, the battery cell further includes an electrode assembly, which is disposed in the housing. The electrode assembly includes a main body region, in which an active material is disposed. The main body region has a first surface facing the end cap, and the end cap has a second surface facing away from the interior of the battery cell. Along the thickness direction of the end cap, the distance between the first surface and the second surface is h, which satisfies 0.3 mm. 2 ≤h*(t1-t2)≤10mm 2 .

[0028] In the above scheme, the electrode assembly is arranged in the outer shell, and the distance between the first surface of the electrode assembly and the second surface of the shell, and the difference between the maximum thickness of the first opening and the thickness of the first main body satisfy the above relationship. When the strength of the first opening is high, there is a certain space between the electrode assembly and the opening, which reduces the interference between the electrode assembly and the components in the shell, and the electrode assembly has little impact on the welding area between the shell and the end cover. At the same time, the space occupied by the first opening is small, the space utilization rate in the shell is high, and the battery cell has a higher energy density.

[0029] According to some embodiments of the present application, 0.4 mm 2 ≤h*(t1-t2)≤7.5mm 2 .

[0030] In the above scheme, compared with 0.3mm 2 ≤h*(t1-t2), when 0.4mm 2 When h*(t1-t2)≤10mm, the first opening can have a higher strength, and there can be a larger space between the electrode assembly and the opening, further reducing the impact of the electrode assembly expansion on the welding area between the shell and the end cover; compared with h*(t1-t2)≤10mm 2 , when h*(t1-t2)≤7.5mm 2 When the first opening is opened, the space occupied by the first opening is small, and the space utilization rate in the shell is high, so the battery cell can have a higher energy density.

[0031] According to some embodiments of the present application, 4.5 mm ≤ h ≤ 20 mm.

[0032] In the above solution, the distance between the first surface and the second surface satisfies the above relationship. On the one hand, it can reduce the risk of interference between the electrode assembly and the components in the shell. On the other hand, the space utilization rate in the shell is reasonably utilized, and the battery cell can have a higher energy density.

[0033] According to some embodiments of the present application, 5 mm ≤ h ≤ 15 mm.

[0034] In the above solution, compared with 4.5mm≤h≤20mm, when 5mm≤h≤15mm, the interference between the electrode assembly and the components in the shell is reduced, and the space in the shell is reasonably utilized, so that the battery cell has a higher energy density.

[0035] According to some embodiments of the present application, t1 and t2 satisfy at least one of the following conditions: (1) 0.1 mm ≤ t1 - t2 ≤ 2 mm; (2) 0.5 mm ≤ t1 ≤ 4 mm; (3) 0.4 mm ≤ t2 ≤ 2 mm.

[0036] In the above solution, when t1 and t2 meet the above conditions, the first opening has a higher strength, and the first opening occupies a smaller assembly space, and the battery cell has a higher energy density.

[0037] According to some embodiments of the present application, t1 and t2 satisfy at least one of the following conditions: (1) 0.2 mm ≤ t1 - t2 ≤ 1 mm (2) 0.7 mm ≤ t1 ≤ 2 mm; (3) 0.4 mm ≤ t2 ≤ 1 mm.

[0038] In the above scheme, compared with t1 and t2 satisfying (1) 0.1mm≤t1-t2≤2mm; (2) 0.5mm≤t1≤4mm; (3) 0.4mm≤t2≤2mm, when t1 and t2 satisfy (1) 0.2mm≤t1-t2≤1mm; (2) 0.7mm≤t1≤2mm; (3) 0.4mm≤t2≤1mm, while reducing the difficulty of processing and manufacturing and improving the strength of the first opening, the first opening occupies a smaller assembly space and the battery cell has a higher energy density.

[0039] According to some embodiments of the present application, the battery cell also includes an electrode assembly, the electrode assembly includes a main body area, the main body area is provided with an active material, the main body area has a first surface facing the end cover, and the first opening portion is pointed along the direction of the first body portion. The first opening portion exceeds the first surface.

[0040] In the above solution, along the direction from the first body portion to the first opening portion, the first opening portion extends beyond the first surface, which can reduce the risk of interference between the first opening portion and the main body portion.

[0041] According to some embodiments of the present application, the shell and the end cover are welded to form a welding area, and the average grain size of the part of the first opening portion other than the welding area is larger than the average grain size of the first main body portion, and the average grain size is the average grain size of the grains in the thickness direction of the first wall.

[0042] In the above scheme, the average grain size of the first opening portion other than the welding area is larger than the average grain size of the first main body portion, which is beneficial to enhancing the strength of the first opening portion, so that the first opening portion has higher strength and reduces the risk of cracking of the shell near the welding area of ​​the shell and the end cover.

[0043] According to some embodiments of the present application, in a cross-section of the first wall parallel to the thickness direction of the first wall, the number of grains in a portion of the first opening below the welding area in the width direction of the cross-section is greater than or equal to 15.

[0044] In the above solution, the number of grains in the width direction of the cross section is greater than or equal to 15, which is beneficial to enhancing the strength of the first opening portion, so that the first opening portion has higher strength.

[0045] According to some embodiments of the present application, the average grain size of the first opening portion excluding the welding area is in a range of 70 μm-1200 μm; and / or the average grain size of the first body portion is in a range of 30 μm-1000 μm.

[0046] In the above solution, the average grain size of the first opening portion and / or the average grain size of the first body portion satisfy the above relationship, which is beneficial to enhancing the strength of the first opening portion, so that the first opening portion has higher strength.

[0047] In a second aspect, an embodiment of the present application provides a battery, which includes a battery cell provided in any of the above embodiments.

[0048] According to some embodiments of the present application, there are multiple battery cells, and the multiple battery cells are stacked along a third direction. The battery also includes an end plate, and the end plate is arranged at the end of the multiple battery cells along the third direction. The third direction, the second direction and the first direction are perpendicular to each other, and along the direction of the first main body portion pointing to the first opening portion, at least a portion of the first opening portion exceeds the end plate.

[0049] In the above solution, the end plates are arranged at the ends of the multiple battery cells in the third direction, and the end plates have a large connection area with the shells of adjacent battery cells to form a constraint on the shells, thereby reducing the risk of the shells cracking near the welding area between the shells and the end covers.

[0050] According to some embodiments of the present application, the end plate is disposed facing the first wall.

[0051] In the above solution, the end plate is arranged facing the first wall, and has a large contact area with the first main body. During the charge and discharge cycle of the battery cell, the end plate can constrain the first wall to reduce the risk of cracking of the shell near the welding area between the shell and the end cover.

[0052] In a third aspect, an embodiment of the present application provides an electrical device, which includes a battery cell or a battery as provided in any of the above embodiments.

[0053] In a fourth aspect, an embodiment of the present application provides an energy storage device, which includes a battery cell or a battery as provided in any of the above embodiments.

[0054] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0056] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0057] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0058] FIG3 is an exploded view of a battery cell provided in some embodiments of the present application;

[0059] FIG4 is a schematic diagram of the assembly of a housing and an electrode assembly according to some embodiments of the present application;

[0060] FIG5 is a cross-sectional view taken along the AA direction of FIG4 ;

[0061] FIG6 is a partial enlarged view of point B in FIG5 ;

[0062] FIG7 is a partial schematic diagram of the assembly of a housing and an electrode assembly according to some embodiments of the present application;

[0063] FIG8 is a cross-sectional view taken along the CC direction of FIG4 ;

[0064] FIG9 is a partial enlarged view of point D in FIG8 ;

[0065] FIG10 is a cross-sectional view of a partial structure of an assembled end cap and a housing according to some embodiments of the present application;

[0066] FIG11 is a schematic diagram of the assembly of an end plate and a plurality of battery cells provided in some embodiments of the present application;

[0067] FIG12 is a schematic diagram of the assembly of the end plate and the battery cell provided in an embodiment of the present application;

[0068] FIG13 is a partial enlarged view of point E in FIG12 .

[0069] In the drawings, the drawings are not drawn to scale.

[0070] Marking instructions: 100 - battery; 10 - housing; 11 - first sub-housing; 12 - second sub-housing; 20 - battery cell; 21 - housing; 211 - housing; 212 - end cap; 2121 - second surface; 213 - first wall; 2131 - first opening; 2131a - first section; 2131b - second section; 2132 - first main body; 2133 - first step surface; 2130 - groove; 214 - second wall; 2141 - second opening; 2141a -third section; 2141b-fourth section; 2142-second main body; 2143-second step surface; 215-bottom wall; 210-welding area; 22-electrode assembly; 22a-first surface; 221-main body; 222-ear; 23-electrode terminal; 24-adapter; 30-end plate; 200-controller; 300-motor; 1000-vehicle; F1-first dividing line; F2-second dividing line; X-first direction; Y-second direction; Z-third direction. DETAILED DESCRIPTION

[0071] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0072] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0073] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0074] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0075] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0076] The term "multiple" in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0077] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0078] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0079] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0080] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0081] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0082] The battery cells may be, but are not limited to, lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, and the like.

[0083] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

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

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

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

[0087] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used.

[0088] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0089] As an example, the negative electrode current collector may be a metal foil or a composite current collector. For example, the metal foil may be silver-plated aluminum, silver-plated stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium.

[0090] In some embodiments, the negative electrode current collector has two opposite surfaces in its thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0091] As an example, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0092] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0093] As an example, the primary material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a separate component positioned between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0094] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0095] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0096] In some embodiments, the electrode assembly is a laminate structure.

[0097] In some embodiments, a battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0098] In some embodiments, the housing includes an end cap and a shell. The shell has an opening, and the end cap closes the opening to form a sealed space for accommodating the electrode assembly, electrolyte, and other substances. The shell may have one or more openings. One or more end caps may also be provided.

[0099] In some embodiments, the housing is provided with at least one electrode terminal, which is electrically connected to a tab of the electrode assembly. The electrode terminal may be directly connected to the tab or indirectly connected to the tab via an adapter. The electrode terminal may be provided on an end cap or on the housing.

[0100] In some embodiments, the housing is provided with an explosion-proof valve for releasing the internal pressure of the battery cell.

[0101] As an example, the battery cell may be a prismatic battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, and a polygonal battery. The polygonal battery is, for example, a hexagonal battery.

[0102] The development of battery technology must take into account multiple design factors at the same time, such as energy density, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery reliability must also be considered.

[0103] In some embodiments, a battery cell includes an outer shell, which includes a housing and an end cap. The housing has an opening, and the end cap is connected to the housing to seal the opening. The end cap is typically welded to the housing to form a weld mark. However, the high temperature during welding of the end cap and housing can easily reduce the strength of the end cap and housing near the weld location. During the charge and discharge cycles of the battery cell, the housing expands and contracts, which can easily cause fatigue cracking in the portion of the housing near the weld between the housing and the end cap, resulting in damage to the housing and reducing the service life and reliability of the battery cell.

[0104] In view of this, an embodiment of the present application provides a technical solution, in which a battery cell includes an outer shell, the outer shell includes a shell and an end cover, the shell includes a first wall, the first wall includes a first opening portion and a first main body portion distributed in sequence along a first direction, the first direction is parallel to the thickness direction of the end cover, the first main body portion is farther away from the opening than the first opening portion, the thickness of the first opening portion is greater than the thickness of the first main body portion, the end cover is connected to the first wall and closes the opening, the maximum thickness of the first opening portion is t1, the thickness of the first main body portion is t2, the dimension of the first wall in the second direction is a, the second direction, the thickness direction of the first wall and the first direction are perpendicular to each other, satisfying 120≤a / (t1-t2)≤4000, which can reduce the risk of fatigue cracking of the shell and make the battery cell have higher reliability.

[0105] In such a battery cell, the larger the size of the first wall in the second direction is, the more the strength of the first opening needs to be increased; the above relationship is satisfied between the size of the first wall in the second direction and the difference between the maximum thickness of the first opening and the thickness of the first main body. On the one hand, it is convenient for processing and manufacturing the first opening, and the first opening can have higher strength, which can reduce the risk of fatigue cracking of the shell near the welding area of ​​the shell and the end cover, and improve the reliability of the battery cell; on the other hand, the first opening occupies a smaller assembly space, and the battery cell can have a higher energy density.

[0106] The battery disclosed in the embodiments of the present application can be used, but is not limited to, in electrical equipment such as vehicles, ships, or aircraft. The battery disclosed in the present application can be used to form a power supply system for the electrical equipment.

[0107] The embodiments of the present application provide an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, an electric bicycle, an electric motorcycle, an electric car, a ship, a spacecraft, etc. 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, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0108] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0109] Please refer to Figure 1, which is a schematic diagram of the structure of the vehicle provided in some embodiments of the present application. Vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can be used as an operating power source for the vehicle 1000, for the circuit system of the vehicle 1000, such as for the working power requirements during the startup, navigation and operation of the vehicle 1000.

[0110] The vehicle 1000 may further include a controller 200 and a motor 300 . The controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0111] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0112] Please refer to Figure 2, which is an exploded view of a battery provided in some embodiments of the present application. The battery 100 includes a housing 10 and a battery cell 20, with the battery cell 20 being housed within the housing 10. The housing 10 is used to provide a storage space for the battery cell 20, and the housing 10 can adopt a variety of structures. In some embodiments, the housing 10 can include a first sub-housing 11 and a second sub-housing 12, which cover each other and together define a storage space for accommodating the battery cell 20. The second sub-housing 12 can be a hollow structure with one end open, and the first sub-housing 11 can be a plate-like structure, with the first sub-housing 11 covering the open side of the second sub-housing 12, so that the first sub-housing 11 and the second sub-housing 12 jointly define a storage space; the first sub-housing 11 and the second sub-housing 12 can also be hollow structures with one end open, with the open side of the first sub-housing 11 covering the open side of the second sub-housing 12.

[0113] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0114] The battery cell 20 may be a secondary battery or a primary battery; the battery cell 20 may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto.

[0115] Please refer to Figure 3, which is an exploded view of a battery cell provided in some embodiments of the present application. As shown in Figure 3, a battery cell 20 includes a housing 21, an electrode assembly 22, and other functional components. Housing 21 includes a shell 211 and an end cap 212. Shell 211 has an opening, and end cap 212 closes the opening, isolating the internal environment of battery cell 20 from the external environment.

[0116] The shell 211 is a component used to cooperate with the end cover 212 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 22, electrolyte and other components. The shell 211 and the end cover 212 can be independent components. The shell 211 can be of various shapes and sizes. Specifically, the shape of the shell 211 can be determined according to the specific shape and size of the electrode assembly 22. The material of the shell 211 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy (such as three-series aluminum), plastic, etc.

[0117] The end cap 212 refers to a component that covers the opening of the shell 211 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 212 can be adapted to the shape of the shell 211 to match the shell 211. Optionally, the end cap 212 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 212 is not easily deformed when squeezed or collided, so that the battery cell 20 can have a higher structural strength and the reliability can also be improved. Functional components such as electrode terminals 23 can be provided on the end cap 212. The electrode terminal 23 can be used to electrically connect to the electrode assembly 22 for outputting or inputting electrical energy of the battery cell 20. The material of the end cap 212 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose any special restrictions on this. In some embodiments, an insulating structure may be provided inside the end cap 212 to isolate the electrical connection components in the housing 211 from the end cap 212 to reduce the risk of short circuits. For example, the insulating structure may be made of plastic, rubber, or the like.

[0118] The electrode assembly 22 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 22 may be contained in the housing 211. The electrode assembly 22 is mainly formed by winding or stacking the positive electrode sheet and the negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The separator is used to separate the positive electrode sheet and the negative electrode sheet to avoid internal short circuits between the positive electrode sheet and the negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet with active materials constitute the main body of the electrode assembly, and the parts of the positive electrode sheet and the negative electrode sheet without active materials each constitute a tab. The positive electrode tab and the negative electrode tab may be located together at one end of the main body or respectively at both ends of the main body.

[0119] Please refer to Figure 3, and further refer to Figures 4 to 6. Figure 4 is a schematic diagram of the assembly of the shell and the electrode assembly provided in some embodiments of the present application. Figure 4 is a schematic diagram of the assembly state of the electrode assembly and the shell before the shell and the end cover are assembled; Figure 5 is a cross-sectional view in the AA direction of Figure 4, and Figure 6 is a local enlarged view of point B in Figure 5.

[0120] The present embodiment provides a battery cell 20, which includes a housing 21. The housing 21 includes a shell 211 and an end cap 212. The shell 211 has an opening and includes a first wall 213. The first wall 213 includes a first opening portion 2131 and a first body portion 2132, which are sequentially distributed along a first direction X. The first direction X is parallel to the thickness direction of the end cap 212. The first body portion 2132 is farther from the opening than the first opening portion 2131. The thickness of the first opening portion 2131 is greater than that of the first body portion 2132. The end cap 212 is connected to the first opening portion 2131 and closes the opening. The maximum thickness of the first opening portion 2131 is t1, the thickness of the first body portion 2132 is t2, and the dimension of the first wall 213 in the second direction Y is a. The second direction Y, the thickness direction of the first wall 213, and the first direction X are perpendicular to each other, satisfying the condition 120≤a / (t1-t2)≤6000.

[0121] In the figure, the direction indicated by the letter X is a first direction, which is parallel to the thickness direction of the end cap 212. The direction indicated by the letter Y is a second direction, which can be parallel to the length direction of the battery cell 20, or the width direction of the battery cell 20.

[0122] Along the first direction X, the first body portion 2132 is farther away from the first opening portion 2131 than the first opening portion 2131 , and the first opening portion 2131 may be surrounded to form an opening.

[0123] In some embodiments, the end cap 212 can be welded to the first wall 213 to form a first weld zone, and a portion of the first opening 2131 can be welded to the end cap 212 to form a first weld zone. In some embodiments, the first weld zone can be referred to as a weld mark.

[0124] In some embodiments, the first body portion 2132 may have a uniform thickness structure, and the thickness of the first body portion 2132 may be the maximum thickness of the first body portion 2132. The first opening portion 2131 may have a uniform thickness structure or a variable thickness structure. When the first opening portion 2131 has a uniform thickness structure, the maximum thickness of the first opening portion 2131 is the thickness at any position of the first opening portion 2131. When the first opening portion 2131 has a variable thickness structure, the maximum thickness of the first opening portion 2131 may be the thickness at the position where the thickness of the first opening portion 2131 is the maximum.

[0125] Optionally, when the first opening portion 2131 is a thickened structure, the thickness of the first opening portion 2131 can gradually decrease from the end away from the first main body portion 2132 toward the end close to the first main body portion 2132, and the area with the largest thickness of the first opening portion 2131 is located at the end away from the first main body portion 2132.

[0126] The larger the dimension of the first wall 213 in the second direction Y, the easier it is for the first wall 213 to expand and deform during the charge and discharge process of the battery cell 20 . Therefore, the strength of the first opening 2131 needs to be increased to reduce the risk of fatigue cracking of the first opening 2131 .

[0127] The smaller the difference between the maximum thickness of the first opening portion 2131 and the thickness of the first main body portion 2132, the more difficult it is to process the first opening portion 2131; the larger the difference between the maximum thickness of the first opening portion 2131 and the thickness of the first main body portion 2132, the larger the assembly space occupied by the first opening portion 2131, which affects the energy density of the battery cell 20.

[0128] According to the battery cell 20 of the embodiment of the present application, the dimension a of the first wall 213 in the second direction Y and the difference (t1-t2) between the maximum thickness of the first opening portion 2131 and the thickness of the first main body portion 2132 satisfy the above-mentioned relationship (120≤a / (t1-t2)≤4000). On the one hand, it is easy to process and manufacture, and the first opening portion 2131 can have higher strength, which can reduce the risk of cracking of the shell 211 near the welding area between the shell 211 and the end cover 212, and improve the reliability of the battery cell 20; on the other hand, the first opening portion 2131 occupies a smaller assembly space, and the battery cell 20 can have a higher energy density.

[0129] a / (t1-t2) may be any value between 120 and 4000. Alternatively, a / (t1-t2) may be, but is not limited to, 120, 160, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, etc.

[0130] In some embodiments, along the thickness direction of the first wall 213 , the first body portion 2132 has a first surface facing the interior of the battery cell 20 , and a portion of the first opening portion 2131 may protrude from the first surface.

[0131] In some embodiments, along the thickness direction of the first wall 213 , the first body portion 2132 has a second surface facing away from the interior of the battery cell 20 , and a portion of the first opening 2131 may protrude from the second surface.

[0132] In some embodiments, along the thickness direction of the first wall 213, the first main body portion 2132 has a first surface facing the interior of the battery cell 20 and a second surface away from the interior of the battery cell 20, and part of the first opening portion 2131 can protrude from the first surface, and part of the first opening portion 2131 can protrude from the second surface.

[0133] In some embodiments, the first opening portion 2131 can be provided separately or integrally. For example, during the manufacturing process of the housing 211, a thickened portion is provided separately from the base of the first wall 213 at the opening of the first wall 213, and the thickened portion and the base are fixedly connected to form the first opening portion 2131. The base forms the first body portion 2132 in the area of ​​the first wall 213 located in the first body portion 2132. For another example, during the manufacturing process of the housing 211, the housing 211 can be stamped and formed, and the housing 211 is an integrally formed structure, forming the first opening portion 2131 at the opening of the first wall 213, and the maximum thickness of the first opening portion 2131 is greater than the thickness of the first body portion 2132.

[0134] The dotted line indicated by letter F1 in FIG. 6 may be a boundary line between the first opening portion 2131 and the first body portion 2132 . For ease of distinction, the boundary line may be a first boundary line F1 .

[0135] In some embodiments, due to the thickness difference between the first opening 2131 and the first body 2132, when a portion of the first opening 2131 protrudes from the first surface, a groove 2130 is formed between the first opening 2131 and the first surface of the first body 2132. The body 221 of the electrode assembly 22 can be disposed within the groove 2130, or the body 221 can be located outside the groove 2130. It should be noted that the groove 2130 is a recessed area formed by the height difference between the first opening 2131 and the first body 2132.

[0136] According to some embodiments of the present application, 400≤a / (t1-t2)≤3000, optionally, 500≤a / (t1-t2)≤2000.

[0137] Compared with 120≤a / (t1-t2)≤6000, when 400≤a / (t1-t2)≤3000 or 500≤a / (t1-t2)≤2000, the first opening 2131 is less difficult to manufacture, the first opening 2131 can have higher strength, and the battery cell 20 has higher energy density.

[0138] Optionally, a / (t1-t2) can be but is not limited to 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2500, 3000, etc.

[0139] According to some embodiments of the present application, 70 mm ≤ a ≤ 600 mm.

[0140] a can be any value between 70 mm and 600 mm. Alternatively, a can be, but is not limited to, 70 mm, 90 mm, 140 mm, 180 mm, 280 mm, 360 mm, 420 mm, 450 mm, 490 mm, 540 mm, 600 mm, etc.

[0141] In the above solution, the dimension a of the first wall 213 in the second direction Y satisfies the above relationship, and the battery cell 20 has a larger dimension in the second direction Y, so that the battery cell 20 can have a higher energy density.

[0142] According to some embodiments of the present application, 100 mm ≤ a ≤ 500 mm.

[0143] In the above solution, compared with 70 mm ≤ a ≤ 600 mm, when 100 mm ≤ a ≤ 500 mm, the battery cell 20 can have a higher energy density and be easier to process and manufacture.

[0144] Optionally, a can be but is not limited to 100mm, 150mm, 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, etc.

[0145] Please refer to Figure 7, which is a partial schematic diagram of the assembly of the housing and the electrode assembly provided in some embodiments of the present application. Figure 7 shows a schematic structural diagram of the first wall of the housing before the housing and the end cap are assembled. According to some embodiments of the present application, the first opening portion 2131 includes a first section 2131a and a second section 2131b that are connected to each other. The first section 2131a, the second section 2131b, and the first body portion 2132 are distributed in sequence along the first direction X. The maximum thickness of the second section 2131b is greater than the thickness of the first body portion 2132. The maximum thickness of the second section 2131b is greater than the maximum thickness of the first section 2131a. The end cap 212 (see Figure 3) is connected to the first section 2131a.

[0146] The first section 2131a, the first section 2131a and the first body portion 2132 are sequentially distributed along the first direction X. The first section 2131a is closer to the opening than the second section 2131b. The first section 2131a is used to connect with the end cover 212.

[0147] Among them, the maximum thickness of the first section 2131a can be t3, and the maximum thickness of the second section 2131b can be t1, satisfying t1>t3, that is, the maximum thickness of the second section 2131b is greater than the maximum thickness of the first section 2131a, so that after the end cover 212 is connected to the first section 2131a, the first opening portion 2131 has higher strength.

[0148] In some embodiments, 0.1 mm ≤ t1 - t3 ≤ 0.2 mm.

[0149] In some embodiments, 0.4 mm ≤ t3 ≤ 3.9 mm.

[0150] Optionally, t3 may be, but is not limited to, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm,

[0151] 3.9mm, etc.

[0152] The second section 2131b is disposed adjacent to the first section 2131a, and at least a portion of the second section 2131b is a heat-affected zone after the end cover 212 and the first section 2131a are welded.

[0153] In the above scheme, the first section 2131a, the second section 2131b and the first main body 2132 are distributed in sequence along the first direction X, and the end cover 212 is connected to the first section 2131a, so that the second section 2131b is adjacent to the connection between the end cover 212 and the first section 2131a, and the maximum thickness of the second section 2131b is greater than the thickness of the first main body 2132. The maximum thickness of the second section 2131b is greater than the maximum thickness of the first section 2131a, so that the first opening 2131 has higher strength, which can reduce the risk of fatigue cracking of the shell 211 near the welding area between the shell 211 and the end cover 212, and improve the service life and reliability of the battery cell 20.

[0154] In some embodiments, before the first section 2131a is connected to the end cover 212, the maximum thickness of the shell 211 in the area where the first section 2131a is located can be greater than the thickness of the first main body 2132. That is, during the manufacturing process of the battery cell 20, the shell 211 in the area where the first section 2131a is located can also be thickened relative to the first main body 2132 to improve the connection firmness between the end cover 212 and the first section 2131a.

[0155] In some embodiments, before the first section 2131a is connected to the end cap 212, the maximum thickness of the housing 211 in the region where the first section 2131a is located can be the same as the maximum thickness of the second section 2131b. That is, the first opening 2131 can have a structure of equal thickness. After the first opening 2131 is welded to the end cap 212, a portion of the housing 211 in the region where the first section 2131a is located is welded to a portion of the end cap 212 to form a first welded zone, and the remaining portion is referred to as the first section 2131a.

[0156] According to some embodiments of the present application, a first step surface 2133 is formed between the second section 2131 b and the first section 2131 a , and the end cover 212 is overlapped on the first step surface 2133 .

[0157] Before the first section 2131a is connected to the end cover 212, the maximum thickness of the shell 211 in the area where the first section 2131a is located is less than the maximum thickness of the second section 2131b. A first step surface 2133 is formed between the second section 2131b and the first section 2131a. The end cover 212 is overlapped on the first step surface 2133 to facilitate the positioning of the end cover 212.

[0158] Please refer to Figures 3 and 4. According to some embodiments of the present application, the shell 211 also includes a second wall 214, which is arranged adjacent to the first wall 213. The second wall 214 is connected to the end cover 212, and the area of ​​the outer surface of the first wall 213 is larger than the area of ​​the outer surface of the second wall 214.

[0159] The second wall 214 is adjacent to the first wall 213 , and the second wall 214 is adjacent to the end cover 212 . The second wall 214 and the first wall 213 together form an opening.

[0160] In some embodiments, the number of first walls 213 can be two, and the two first walls 213 are arranged opposite to each other along the third direction Z; the number of second walls 214 can be two, and the two second walls 214 are arranged opposite to each other along the second direction Y, and the two second walls 214 and the two first walls 213 form a accommodating cavity with an opening, and the electrode assembly is accommodated in the accommodating cavity.

[0161] The outer surface area of ​​the first wall 213 is larger than the outer surface area of ​​the second wall 214. The first wall 213 may be the larger wall of the housing 211. For example, the outer surface area of ​​the first wall 213 may be larger than the outer surface area of ​​the end cap 212. The first wall 213 may be the largest surface of the battery cell 20. During the charge and discharge cycles of the battery cell 20, the first wall 213 is subjected to significant forces. The thickening of the first opening 2131 of the first wall 213 can improve the strength of the first opening 2131, thereby reducing the risk of fatigue cracking of the housing 211 near the weld area between the housing 211 and the end cap 212.

[0162] Please refer to Figure 8, which is a cross-sectional view taken along the CC direction of Figure 4. According to some embodiments of the present application, the second wall 214 includes a second opening portion 2141 and a second body portion 2142 sequentially distributed along the first direction X. The second body portion 2142 is farther away from the second opening portion 2141, and the maximum thickness of the second opening portion 2141 is greater than the thickness of the second body portion 2142.

[0163] The dotted line indicated by the letter F2 in FIG. 9 may be a boundary line between the second opening portion 2141 and the second body portion 2142 . For ease of distinction, the boundary line may be a second boundary line F2 .

[0164] Along the first direction X, the second body portion 2142 is farther away from the second opening portion 2141, and the second opening portion 2141 can be surrounded by an opening. In the figure, the maximum thickness of the second opening portion 2141 is t4, and the thickness of the second body portion is t5, satisfying t4>t5.

[0165] In some embodiments, a portion of the second opening 2141 may be welded to the end cap 212 to form a second weld zone. In some embodiments, the second weld zone may be referred to as a weld mark.

[0166] In some embodiments, the second body portion 2142 may have a uniform thickness structure, and the thickness of the second body portion 2142 may be the maximum thickness of the second body portion 2142. The second opening portion 2141 may have a uniform thickness structure or a variable thickness structure. When the second opening portion 2141 has a uniform thickness structure, the maximum thickness of the second opening portion 2141 is the thickness at any position of the second opening portion 2141. When the second opening portion 2141 has a variable thickness structure, the maximum thickness of the second opening portion 2141 may be the thickness at the position where the second opening portion 2141 has the maximum thickness.

[0167] Optionally, when the second opening portion 2141 is a thickened structure, the thickness of the second opening portion 2141 can gradually decrease from the end away from the second main body portion 2142 toward the end close to the second main body portion 2142, and the area with the largest thickness of the second opening portion 2141 is located at the end away from the second main body portion 2142.

[0168] In the above solution, the second opening portion 2141 is close to the opening, and the second opening portion 2141 is thickened, which can improve the strength of the second wall 214 and reduce the risk of cracking of the shell 211 near the welding area between the shell 211 and the end cover 212 when the battery cell 20 thermally runs away or the gas production is too large.

[0169] 4 , according to some embodiments of the present application, a dimension of the second wall 214 in the third direction Z is b. The third direction Z, the second direction Y, and the first direction X are perpendicular to each other, satisfying 40 mm ≤ b.

[0170] When the second wall 214 is relatively small in the third direction Z, the second wall 214 is less likely to crack during the charge and discharge process of the battery cell 20. When the second wall 214 is relatively large in the third direction Z, the second opening 2141 and the first opening 2131 both need to be thickened, making the manufacturing of the housing 211 more difficult.

[0171] In the above scheme, the size of the second wall 214 in the third direction Z satisfies the above relationship, which can improve the strength of the second wall 214, restrain the expansion and deformation of the second wall 214, reduce the risk of cracking of the shell 211 near the welding area between the shell 211 and the end cover 212, and has low processing and manufacturing difficulty.

[0172] Optionally, 40mm≤b≤120mm.

[0173] Optionally, b can be any value between 40 mm and 120 mm. Optionally, b can be, but is not limited to, 40 mm, 48 mm, 54 mm, 60 mm, 66 mm, 72 mm, 78 mm, 84 mm, 92 mm, 104 mm, 110 mm, 120 mm, etc.

[0174] In some embodiments, when viewed along the thickness direction of the end cover 212 , the second opening 2141 may partially overlap with the electrode assembly 22 , or the second opening 2141 may not overlap with the electrode assembly 22 .

[0175] Please refer to Figure 8 and further refer to Figure 9, which is a partial enlarged view of point D in Figure 8. According to some embodiments of the present application, the second opening portion 2141 includes a third section 2141a and a fourth section 2141b that are connected to each other. The third section 2141a, the fourth section 2141b, and the second body portion 2142 are sequentially distributed along the first direction X. The maximum thickness of the fourth section 2141b is greater than the thickness of the second body portion 2142, and the maximum thickness of the fourth section 2141b is greater than the maximum thickness of the third section 2141a. A second step surface 2143 is formed between the fourth section 2141b and the third section 2141a. The end cover 212 (see Figure 3) overlaps the second step surface 2143 and is connected to the third section 2141a.

[0176] The third section 2141 a , the fourth section 2141 b and the second body portion 2142 are sequentially distributed along the first direction X. The third section 2141 a is closer to the opening than the fourth section 2141 b . The third section 2141 a is used to connect with the end cover 212 .

[0177] The maximum thickness of the third section 2141a can be t6, and the maximum thickness of the fourth section 2141b can be t4, satisfying t4>t6, that is, the maximum thickness of the fourth section 2141b is greater than the maximum thickness of the third section 2141a, so that after the end cover 212 is connected to the third section 2141a, the second opening portion 2141 has higher strength.

[0178] Since the second wall 214 forms the side surface of the battery cell 20, during the manufacturing process of the battery cell 20, the shell 211 is typically thinned in the region of the third section 2141a so that the maximum thickness of this region is less than the thickness of the second body portion 2142, thereby facilitating welding of the second wall 214 to the end cap 212. In some embodiments of the present application, before the third section 2141a is connected to the end cap 212, the shell 211 in the region of the third section 2141a may be thickened so that the maximum thickness of the shell 211 in the region of the third section 2141a is greater than or equal to the thickness of the second body portion 2142, thereby enhancing the secure connection between the end cap 212 and the third section 2141a. In other embodiments of the present application, before the third section 2141a is connected to the end cover 212, the area of ​​the shell 211 in the third section 2141a can be thickened, and the maximum thickness of the area of ​​the shell 211 in the third section 2141a can be less than the thickness of the second main body 2142 to improve the connection firmness between the end cover 212 and the third section 2141a.

[0179] The fourth section 2141b is disposed adjacent to the third section 2141a, and at least a portion of the fourth section 2141b is a heat-affected zone after the end cover 212 and the third section 2141a are welded.

[0180] During the manufacturing process of the battery cell 20 , since the second step surface 2143 is formed between the fourth section 2141 b and the third section 2141 a , the end cover 212 can be overlapped with the second step surface 2143 to achieve positioning of the end cover 212 .

[0181] In the above scheme, the third section 2141a, the fourth section 2141b and the second main body 2142 are distributed in sequence along the first direction X, and the end cover 212 is connected to the third section 2141a, so that the fourth section 2141b is adjacent to the connection between the end cover 212 and the third section 2141a, and the maximum thickness of the fourth section 2141b is greater than the thickness of the second main body 2142. The maximum thickness of the fourth section 2141b is greater than the maximum thickness of the third section 2141a, so that the second opening 2141 has higher strength, which can reduce the risk of cracking of the shell 211 near the welding area between the shell 211 and the end cover 212 when the battery cell 20 thermally runs away or the gas production is too large, thereby improving the service life and reliability of the battery cell 20.

[0182] Please refer to Figures 3 and 5. According to some embodiments of the present application, the shell 211 also includes a bottom wall 215. The number of the first wall 213 and the second wall 214 are both two. The two first walls 213 are arranged opposite to each other along the third direction Z, and the two second walls 214 are arranged opposite to each other along the second direction Y. The two first walls 213 and the two second walls 214 are arranged around the bottom wall 215. The two first walls 213 and the two second walls 214 are integrally formed with the bottom wall 215. The bottom wall 215 and the end cover 212 are arranged opposite to each other in the first direction X.

[0183] Please refer to Figure 3 and further to Figure 10, which is a cross-sectional view of a partial structure of the end cap and the shell after assembly according to some embodiments of the present application. According to some embodiments of the present application, the battery cell 20 also includes an electrode assembly 22, which is disposed in the shell 21. The electrode assembly 22 includes a main body 221, the main body 221 having a first surface 22a facing the end cap 212, and the end cap 212 having a second surface 2121 facing away from the interior of the battery cell 20. Along the thickness direction of the end cap 212, the distance between the first surface 22a and the second surface 2121 is h, which satisfies 0.3mm. 2 ≤h*(t1-t2)≤10mm 2 .

[0184] In some embodiments, the electrode assembly 22 further includes a tab 222 extending from the main body 221 . The tab 222 may extend from the first surface 22 a .

[0185] The second surface 2121 may be an outer surface of the end cover 212 .

[0186] In the above scheme, the electrode assembly 22 is arranged in the outer shell 21, and the distance between the first surface 22a of the electrode assembly 22 and the second surface 2121 of the shell 211, and the difference between the maximum thickness of the first opening portion 2131 and the thickness of the first main body portion 2132 satisfy the above relationship. When the strength of the first opening portion 2131 is high, there is a certain space between the electrode assembly 22 and the opening, which reduces the interference between the electrode assembly 22 and the components in the shell 211, and the electrode assembly 22 has little effect on the welding area between the shell 211 and the end cover 212. At the same time, the first opening portion 2131 occupies a small space, the space utilization rate in the shell 211 is high, and the battery cell 20 has a higher energy density.

[0187] h*(t1-t2) can be 0.3mm 2 With 10mm 2 Optionally, h*(t1-t2) can be but not limited to 0.3 mm. 2 , 0.5mm 2 , 0.8mm 2 , 1mm2 , 1.5mm 2 , 2mm 2 , 2.5mm 2 , 3mm 2 , 3.5mm 2 , 4mm 2 , 4.5mm 2 , 5mm 2 , 5.5mm 2 , 6mm 2 , 6.5mm 2 , 7mm 2 , 7.5mm 2 , 8mm 2 , 8.5mm 2 , 9mm 2 , 9.5mm 2 , 10mm 2 wait.

[0188] According to some embodiments of the present application, 0.4 mm 2 ≤h*(t1-t2)≤7.5mm 2 .

[0189] Optionally, h / (t1-t2) may be, but is not limited to, 0.4 mm. 2 , 0.8mm 2 , 1mm 2 , 1.5mm 2 , 2mm 2 , 2.5mm 2 , 3mm 2 , 3.5mm 2 , 4mm 2 , 4.5mm 2 , 5mm 2 , 5.5mm 2 , 6mm 2 , 6.5mm 2 , 7mm 2 , 7.5mm 2 wait.

[0190] In the above scheme, compared with 0.3mm 2 ≤h*(t1-t2), when 0.4mm 2 When h*(t1-t2)≤10mm, the first opening 2131 can have a higher strength, and there can be a larger space between the electrode assembly and the opening, further reducing the impact of the electrode assembly expansion on the welding area between the shell and the end cover; compared with h*(t1-t2)≤10mm 2 , when h*(t1-t2)≤7.5mm 2When the first opening is opened, the space occupied by the first opening is small, and the space utilization rate in the shell is high, so the battery cell can have a higher energy density.

[0191] According to some embodiments of the present application, 4 mm ≤ h ≤ 20 mm.

[0192] h can be any value between 4.5mm and 20mm. Alternatively, h can be, but is not limited to, 4mm, 4.5mm, 5.5mm, 6.5mm, 7.5mm, 8.5mm, 9.5mm, 10.5mm, 11.5mm, 12.5mm, 13.5mm, 14.5mm,

[0193] 15.5mm, 16.5mm, 17.5mm, 18.5mm, 19.5mm, 20mm, etc.

[0194] In the above scheme, the distance between the first surface 22a and the second surface 2121 satisfies the above relationship. On the one hand, it can reduce the risk of interference between the electrode assembly 22 and the components in the shell 211. On the other hand, the space utilization rate in the shell 211 is reasonably utilized, and the battery cell 20 can have a higher energy density.

[0195] According to some embodiments of the present application, 4.5 mm ≤ h ≤ 15 mm.

[0196] Optionally, h can be but is not limited to 4.5mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, etc.

[0197] In the above solution, compared with 4.5mm≤h≤20mm, when 5mm≤h≤15mm, the interference between the electrode assembly 22 and the components in the shell 211 is reduced, and the space in the shell 211 is reasonably utilized, so that the battery cell 20 has a higher energy density.

[0198] According to some embodiments of the present application, t1 and t2 satisfy at least one of the following conditions: (1) 0.1 mm ≤ t1 - t2 ≤ 2 mm; (2) 0.5 mm ≤ t1 ≤ 4 mm; (3) 0.4 mm ≤ t2 ≤ 2 mm.

[0199] The maximum thickness t1 of the first opening portion 2131 and the thickness t2 of the first main body portion 2132 satisfy the above relationship. The first opening portion 2131 is easy to process and manufacture, has high strength, occupies a small assembly space, and the battery cell 20 has a high energy density.

[0200] t1 can be any value between 0.5 mm and 4 mm. Alternatively, t1 can be, but is not limited to, 0.5 mm, 0.9 mm, 1.3 mm, 1.7 mm, 2.1 mm, 2.5 mm, 2.9 mm, 3.1 mm, 3.6 mm, 4 mm, etc.

[0201] t2 can be any value between 0.4 mm and 2 mm. Optionally, t2 can be, but is not limited to, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 1.9 mm, 2 mm, etc.

[0202] t1-t2 can be any value between 0.1 mm and 2 mm. Optionally, t1-t2 can be, but is not limited to, 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1.1 mm, 1.3 mm, 1.5 mm, 1.7 mm, 2 mm, etc.

[0203] According to some embodiments of the present application, t1 and t2 satisfy at least one of the following conditions: (1) 0.2 mm ≤ t1 - t2 ≤ 1 mm; (2) 0.7 mm ≤ t1 ≤ 2 mm; (3) 0.4 mm ≤ t2 ≤ 1 mm.

[0204] In the above scheme, compared with t1 and t2 satisfying (1) 0.1mm≤t1-t2≤2mm; (2) 0.5mm≤t1≤4mm; (3) 0.4mm≤t2≤2mm, when t1 and t2 satisfy (1) 0.2mm≤t1-t2≤1mm; (2) 0.7mm≤t1≤2mm; (3) 0.4mm≤t2≤1mm, when the electrode assembly 22 does not interfere with the components in the shell 211, the maximum thickness of the first opening portion 2131 and the thickness of the first main body portion 2132 satisfy the above relationship. While reducing the difficulty of processing and manufacturing and improving the strength of the first opening portion 2131, the first opening portion 2131 occupies a smaller assembly space, and the battery cell 20 has a higher energy density.

[0205] Optionally, t1 may be, but is not limited to, 0.7 mm, 0.85 mm, 1 mm, 1.15 mm, 1.3 mm, 1.45 mm, 1.6 mm, 1.75 mm, 2 mm, etc.

[0206] Alternatively, t2 may be, but is not limited to, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 1 mm, etc.

[0207] Optionally, t1-t2 may be, but is not limited to, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc.

[0208] According to some embodiments of the present application, t4 satisfies: 0.5 mm ≤ t4 ≤ 5 mm.

[0209] Optionally, t4 may be, but is not limited to, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc.

[0210] Optionally, 0.9mm≤t4≤2.2mm.

[0211] Optionally, t4 may be, but is not limited to, 0.9 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, etc.

[0212] According to some embodiments of the present application, t5 satisfies: 0.4 mm ≤ t5 ≤ 3 mm.

[0213] Optionally, t5 may be, but is not limited to, 0.4 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc.

[0214] Optionally, 0.7mm≤t5≤1.2mm.

[0215] Optionally, t5 may be, but is not limited to, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, etc.

[0216] According to some embodiments of the present application, t6 satisfies: 0.1 mm ≤ t4 - t6 ≤ 0.2 mm.

[0217] According to some embodiments of the present application, the battery cell 20 also includes an electrode assembly 22, the electrode assembly 22 includes a main body 221, the main body 221 is provided with an active material, the main body 221 has a first surface 22a facing the end cover 212, and the first opening portion 2131 is pointed along the direction of the first body portion 2132, and the first opening portion 2131 exceeds the first surface 22a.

[0218] When viewed along the thickness direction of the first wall 213 , the first opening 2131 does not overlap with the main body 221 .

[0219] In the above solution, along the direction from the first body portion 2132 to the first opening portion 2131 , the first opening portion 2131 extends beyond the first surface 22 a , which can reduce the risk of interference between the first opening portion 2131 and the main body portion 221 .

[0220] In some embodiments, along the direction from the second body portion 2142 to the second opening portion 2141 , the second opening portion 2141 extends beyond the first surface 22 a .

[0221] When viewed along the thickness direction of the first wall 213 , the second opening 2141 does not overlap with the main body 221 .

[0222] In the above solution, along the direction from the second body portion 2142 to the second opening portion 2141 , the second opening portion 2141 extends beyond the first surface 22 a , which can reduce the risk of interference between the second opening portion 2141 and the main body portion 221 .

[0223] Please refer to Figure 10. According to some embodiments of the present application, the shell 211 and the end cover 212 are welded to form a welding area 210. The average grain size of the portion of the first opening portion 2131 other than the welding area 210 is larger than the average grain size of the first main body portion 2132. The average grain size is the average grain size of the grains in the thickness direction of the first wall 213.

[0224] The welding area 210 is an area formed by welding the shell 211 and the end cover 212. In some embodiments, the welding area 210 can be called a weld mark.

[0225] The thickness direction of the first wall 213 may be parallel to the Z direction.

[0226] The test method standard reference for average grain size is: GB / T 6394-2017 "Method for determination of average grain size of metals" and GB / T 13298-2017 "Metallic materials - Determination of grain size by electron microscopy".

[0227] In the above scheme, the average grain size of the first opening portion 2131 except the welding area 210 is larger than the average grain size of the first main body portion 2132, which is beneficial to enhancing the strength of the first opening portion 2131, so that the first opening portion 2131 has higher strength, and reduces the risk of cracking of the shell 211 near the welding area 210 of the shell 211 and the end cover 212.

[0228] According to some embodiments of the present application, in a cross-section of the first wall 213 parallel to the thickness direction of the first wall 213 , the number of grains in the portion of the first opening 2131 located below the welding area 210 in the width direction of the cross-section is greater than or equal to 15.

[0229] The width direction of the cross section may be parallel to the Z direction.

[0230] "The portion of the first opening portion 2131 located below the welding area 210" refers to the portion of the first opening portion 2131 located below the welding area 210 in the direction in which the first opening portion 2131 points to the first main body portion 2132 in the X direction in Figure 10, that is, the portion of the first opening portion 2131 located away from the welding area 210 along the direction in which the first opening portion 2131 points to the first main body portion 2132.

[0231] In the above solution, in the width direction of the cross section, the number of grains is greater than or equal to 15, which is beneficial to enhancing the strength of the first opening portion 2131, so that the first opening portion 2131 has higher strength.

[0232] According to some embodiments of the present application, the average grain size of the first opening portion 2131 excluding the welding region 210 is in a range of 70 μm to 1200 μm; and / or the average grain size of the first body portion 2132 is in a range of 30 μm to 1000 μm.

[0233] Optionally, the average grain size of the portion of the first opening 2131 other than the welding area 210 may be, but is not limited to, 70 μm, 80 μm, 90 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, 1100 μm, 1200 μm, etc.

[0234] Optionally, the average grain size of the first body portion 2132 may be, but is not limited to, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, etc.

[0235] In the above solution, the average grain size of the first opening portion 2131 and / or the average grain size of the first body portion 2132 satisfy the above relationship, which is beneficial to enhancing the strength of the first opening portion 2131, so that the first opening portion 2131 has higher strength.

[0236] According to some embodiments of the present application, the average grain size of the second opening portion 2141 excluding the welding region 210 is larger than the average grain size of the second body portion 2142 , where the average grain size is the average grain size of the grains in the thickness direction of the second wall 214 .

[0237] In the above scheme, the average grain size of the second opening portion 2141 other than the welding area 210 is larger than the average grain size of the second main body portion 2142, which is beneficial to enhancing the strength of the second opening portion 2141, so that the second opening portion 2141 has higher strength, reducing the risk of cracking of the shell 211 near the welding area 210 of the shell 211 and the end cover 212.

[0238] According to some embodiments of the present application, in a cross-section of the second wall 214 parallel to the thickness direction of the second wall 214 , the portion of the second opening 2141 located below the welding area 210 has a number of grains greater than or equal to 15 in the width direction of the cross-section.

[0239] The width direction of the cross section is parallel to the Y direction.

[0240] "The portion of the second opening portion 2141 located below the welding area 210" refers to the portion of the second opening portion 2141 located below the welding area 210 in the direction in which the second opening portion 2141 points to the second main body portion 2142 in the X direction, that is, the portion of the second opening portion 2141 located away from the welding area 210 along the direction in which the second opening portion 2141 points to the second main body portion 2142.

[0241] In the above solution, in the width direction of the cross section, the number of grains is greater than or equal to 15, which is beneficial to enhancing the strength of the second opening portion 2141, so that the second opening portion 2141 has higher strength.

[0242] According to some embodiments of the present application, the average grain size of the second opening portion 2141 excluding the welding region 210 is in a range of 70 μm to 1200 μm; and / or the average grain size of the second body portion 2142 is in a range of 30 μm to 1000 μm.

[0243] Optionally, the average grain size of the second opening portion 2141 other than the welding area 210 may be, but is not limited to, 70 μm, 80 μm, 90 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, 1100 μm, 1200 μm, etc.

[0244] Optionally, the average grain size of the second body portion 2142 may be, but is not limited to, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, etc.

[0245] In the above solution, the average grain size of the second opening portion 2141 and / or the average grain size of the second body portion 2142 satisfies the above relationship, which is beneficial to enhancing the strength of the second opening portion 2141, so that the second opening portion 2141 has higher strength.

[0246] According to some embodiments of the present application, the shell 211 is a prismatic structure with openings at both ends, and there are two end covers 212 , which respectively close the two openings.

[0247] When the housing 211 is a prismatic structure, the battery cell 20 may be a square battery. In other embodiments, the housing 211 may be a hexagonal prism, an octagonal prism, or the like.

[0248] When the positive electrode tab and the negative electrode tab are arranged at both ends of the electrode assembly 22, the shell 211 has two openings, and the positive electrode terminal and the negative electrode terminal can be respectively arranged on the two end covers 212 so as to be electrically connected to the positive electrode tab and the negative electrode tab respectively, so as to facilitate the charging and discharging of the battery cell 20.

[0249] In the above solution, openings are respectively provided at both ends of the shell 211 , and both openings are thickened to reduce the risk of the shell 211 cracking near the welding area between the shell 211 and the end cover 212 .

[0250] According to some embodiments of the present application, an embodiment of the present application provides a battery 100, which includes a battery cell 20 provided in any of the above embodiments.

[0251] Please refer to Figures 11 to 13. Figure 11 is a schematic diagram of the assembly of the end plate and multiple battery cells provided in some embodiments of the present application. Figure 12 is a schematic diagram of the assembly of the end plate and battery cells provided in an embodiment of the present application. Figure 13 is a partial enlarged view of point E in Figure 12.

[0252] According to some embodiments of the present application, there are multiple battery cells 20, and the multiple battery cells 20 are stacked along the third direction Z. The battery 100 also includes an end plate 30. Along the third direction Z, the end plate 30 is arranged at the end of the multiple battery cells 20. The third direction Z, the second direction Y and the first direction X are perpendicular to each other, and the direction along the first main body portion 2132 points to the first opening portion 2131. At least a portion of the first opening portion 2131 exceeds the end plate 30.

[0253] Multiple battery cells 20 are stacked along a third direction Z. Along the third direction Z, end plates 30 are arranged at the ends of the multiple battery cells 20. The end plates 30 are connected to the battery cells 20 at the ends of the multiple battery cells 20 in the third direction Z. The end plates 30 can limit the battery cells 20 at the ends and restrain the deformation of the battery cells 20.

[0254] In the above scheme, the end plate 30 is arranged at the end of multiple battery cells 20 in the third direction Z, and the end plate 30 has a large connection area with the shell 211 of the adjacent battery cell 20 to form a constraint on the shell 211, thereby reducing the risk of cracking of the shell 211 near the welding area between the shell 211 and the end cover 212.

[0255] According to some embodiments of the present application, the end plate 30 is disposed facing the first wall 213 .

[0256] In the above scheme, the end plate 30 is arranged facing the first wall 213, and the end plate 30 has a large contact area with the first main body 2132. During the charge and discharge cycle of the battery cell 20, the end plate 30 can constrain the first wall 213 to reduce the risk of cracking of the shell 211 near the welding area between the shell 211 and the end cover 212.

[0257] According to some embodiments of the present application, an electric device is provided, which includes a battery cell 20 or a battery 100 provided in any one of the above embodiments.

[0258] The electrical equipment may be any of the above-mentioned systems or devices using the battery cell 20 or the battery 100 , and the battery cell 20 or the battery 100 is used to provide electrical energy.

[0259] According to some embodiments of the present application, an energy storage device is provided. The energy storage device includes a battery cell 20 or a battery 100 as provided in any one of the above embodiments.

[0260] According to some embodiments of the present application, referring to Figures 3 to 10 , a battery cell 20 is provided. The battery cell 20 is a rectangular parallelepiped. The battery cell 20 includes a housing 21, an electrode assembly 22, and an electrode terminal 23. The electrode assembly 22 is disposed within the housing 21. The housing 21 includes a shell 211 and an end cap 212. The electrode terminal 23 is disposed in the end cap 212. The electrode terminal 23 is connected to the tab 222 of the electrode assembly 22 via an adapter 24. The shell 211 has an opening, and the shell 211 includes two first walls 213 arranged opposite to each other along the third direction Z, two second walls 214 arranged opposite to each other along the second direction Y, and a bottom wall 215. The two first walls 213 and the two second walls 214 are arranged around the bottom wall 215, and the two first walls 213 and the two second walls 214 are integrally formed with the bottom wall 215. The bottom wall 215 and the end cover 212 are arranged opposite to each other in the first direction X, and the end cover 212 is connected to the first wall 213 and the second wall 214 to close the opening.

[0261] The first wall 213 includes a first opening portion 2131 and a first main body portion 2132 distributed in sequence along the first direction X. The first main body portion 2132 is farther away from the opening than the first opening portion 2131. The thickness of the first opening portion 2131 is greater than the thickness of the first main body portion 2132. The maximum thickness of the first opening portion 2131 is t1, the thickness of the first main body portion 2132 is t2, and the dimension of the first wall 213 in the second direction Y is a, satisfying 120≤a / (t1-t2)≤6000.

[0262] The second wall 214 includes a second opening portion 2141 and a second main body portion 2142, which are sequentially arranged along the first direction X. The second main body portion 2142 is further away from the second opening portion 2141. The second opening portion 2141 includes a third section 2141a and a fourth section 2141b, which are interconnected. The third section 2141a, the fourth section 2141b, and the second main body portion 2142 are sequentially arranged along the first direction X. The end cap 212 is connected to the third section 2141a. The maximum thickness of the fourth section 2141b is greater than that of the second main body portion 2142, and the maximum thickness of the fourth section 2141b is greater than that of the third section 2141a. A second stepped surface 2143 is formed between the fourth section 2141b and the third section 2141a, and the end cap 212 overlaps the second stepped surface 2143.

[0263] According to the battery cell 20 of the embodiment of the present application, the dimension of the first wall 213 in the second direction Y and the difference between the maximum thickness of the first opening portion 2131 and the thickness of the first main body portion 2132 satisfy the above-mentioned relationship. On the one hand, it is convenient for processing and manufacturing, and the first opening portion 2131 can have higher strength, which can reduce the risk of fatigue cracking of the shell 211 near the welding area of ​​the shell 211 and the end cover 212, and improve the reliability of the battery cell 20; on the other hand, the first opening portion 2131 occupies a smaller assembly space, and the battery cell 20 can have a higher energy density. The end cover 212 overlaps the second step surface 2143 to facilitate the positioning of the end cover 212; at least a portion of the fourth section 2141b is the heat-affected zone after welding the end cover 212 and the third section 2141a. The maximum thickness of the fourth section 2141b is greater than the thickness of the second main body 2142, and the maximum thickness of the fourth section 2141b is greater than the maximum thickness of the third section 2141a. This can reduce the risk of cracking of the shell 211 near the welding area between the shell 211 and the end cover 212 when the battery cell 20 is in thermal runaway or the gas production is too large, reduce the risk of cracking of the second wall 214, and improve the reliability of the battery cell 20.

[0264] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A battery cell, comprising: a housing including a housing body and an end cap, the housing body having an opening, the housing body including a first wall, the first wall including a first opening portion and a first body portion sequentially distributed in a first direction, the first direction being parallel to the thickness direction of the end cap, the first body portion being farther from the opening than the first opening portion, the thickness of the first opening portion being greater than the thickness of the first body portion, and the end cap being connected to the first opening portion and closing the opening; Wherein, the maximum thickness of the first opening is t 1 , the thickness of the first body portion is t 2 , the dimension of the first wall in the second direction is a, and the second direction, the thickness direction of the first wall, and the first direction are perpendicular to each other pairwise, satisfying 120 ≤ a / (t 1 -t 2 ) ≤ 6000.

2. The battery cell according to claim 1, wherein, 400 ≤ a / (t 1 -t 2 ) ≤ 3000, optionally, 500 ≤ a / (t 1 -t 2 ) ≤ 2000。 3. The battery cell according to claim 1 or 2, wherein, 70mm ≤ a ≤ 600mm.

4. The battery cell according to any one of claims 1 - 3, wherein, 100mm ≤ a ≤ 500mm.

5. The battery cell according to any one of claims 1 - 4, wherein, the first opening portion includes a first section and a second section connected to each other, the first section, the second section, and the first body portion being sequentially distributed in the first direction, the maximum thickness of the second section being greater than the thickness of the first body portion, the maximum thickness of the second section being greater than the maximum thickness of the first section, and the end cap being connected to the first section.

6. The battery cell according to claim 5, wherein, a first step surface is formed between the second section and the first section, and the end cap overlaps on the first step surface.

7. The battery cell according to any one of claims 1 - 6, wherein, the housing body further includes a second wall, the second wall being disposed adjacent to the first wall, the second wall being connected to the end cap, and the area of the outer surface of the first wall being greater than the area of the outer surface of the second wall.

8. The battery cell according to claim 7, wherein, the second wall includes a second opening portion and a second body portion sequentially distributed in the first direction, the second body portion being farther from the opening than the second opening portion, and the maximum thickness of the second opening portion being greater than the thickness of the second body portion.

9. The battery cell according to claim 8, wherein, the size of the second wall in a third direction is b, the third direction, the second direction, and the first direction being perpendicular to each other pairwise, satisfying 40mm ≤ b.

10. The battery cell according to claim 8 or 9, wherein, the second opening portion includes a third section and a fourth section connected to each other, the third section, the fourth section, and the second body portion being sequentially distributed in the first direction, the maximum thickness of the fourth section being greater than the thickness of the second body portion, the maximum thickness of the fourth section being greater than the maximum thickness of the third section, a second step surface being formed between the fourth section and the third section, and the end cap overlapping on the second step surface and being connected to the third section.

11. The battery cell according to any one of claims 1 - 10, wherein, The battery cell further includes an electrode assembly disposed within the housing. The electrode assembly includes a main body portion provided with active material. The main body portion has a first surface facing the end cap, and the end cap has a second surface facing away from the interior of the battery cell. Along the thickness direction of the end cap, the distance between the first surface and the second surface is h, satisfying 0.3 mm 2 ≤h*(t 1 -t 2 )≤10 mm 2 .

12. The battery cell according to claim 11, wherein, 0.4mm 2 ≤h*(t 1 -t 2 )≤7.5mm 2 。 13. The battery cell according to claim 11 or 12, wherein, 4mm ≤ h ≤ 20mm.

14. The battery cell according to claim 13, wherein, 4.5 mm ≤ h ≤ 15 mm.

15. The battery cell according to any one of claims 1-14, wherein, t 1 、t 2 satisfies at least one of the following conditions: (1) 0.1mm ≤ t 1 -t 2 ≤ 2mm; (2) 0.5 mm ≤ t 1 ≤ 4 mm; (3) 0.4 mm ≤ t 2 ≤ 2 mm.

16. The battery cell according to claim 15, wherein, t 1 、t 2 satisfy at least one of the following conditions: (1) 0.2 mm ≤ t 1 -t 2 ≤ 1 mm; (2) 0.7 mm ≤ t 1 ≤ 2 mm; (3) 0.4 mm ≤ t 2 ≤ 1 mm.

17. The battery cell according to any one of claims 1-16, wherein, the battery cell further includes an electrode assembly, the electrode assembly includes a main body portion, the main body portion is provided with an active material, the main body portion has a first surface facing the end cover, along the direction from the first body portion to the first opening portion, the first opening portion extends beyond the first surface.

18. The battery cell according to any one of claims 1-17, wherein, the housing and the end cover are welded to form a welding area, the average grain size of the portion of the first opening portion other than the welding area is greater than the average grain size of the first body portion, and the average grain size is the average grain size of the grains in the thickness direction of the first wall.

19. The battery cell according to claim 18, wherein, in a cross-section of the first wall parallel to the thickness direction of the first wall, for the portion of the first opening portion located below the welding area, in the width direction of the cross-section, the number of grains is greater than or equal to 15.

20. The battery cell according to claim 18 or 19, wherein, the average grain size range of the portion of the first opening portion other than the welding area is 70 μm - 1200 μm; and / or, the average grain size range of the first body portion is 30 μm - 1000 μm.

21. A battery, comprising the battery cell according to any one of claims 1-20.

22. The battery according to claim 21, wherein, the number of the battery cells is plural, the plural battery cells are stacked along a third direction, the battery further includes an end plate, along the third direction, the end plate is disposed at the end of the plural battery cells, the third direction, the second direction and the first direction are perpendicular to each other pairwise, along the direction from the first body portion to the first opening portion, at least a part of the first opening portion extends beyond the end plate.

23. The battery according to claim 22, wherein, the end plate faces the first wall.

24. An electrical device, comprising the battery cell according to any one of claims 1-20 or the battery according to any one of claims 21-23, and the battery cell or the battery is used to provide electrical energy.

25. An energy storage device, comprising the battery cell according to any one of claims 1-20 or the battery according to any one of claims 21-23.

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