Battery monomer, battery, electric equipment and energy storage device

Abstract

The embodiment of the utility model provides a battery monomer, a battery, electric equipment and an energy storage device. The battery cell includes a housing. The shell comprises a shell body and an end cover, the shell body is provided with an opening and comprises a first wall, the first wall comprises a first opening part and a first body part which are sequentially distributed in the first direction, the first direction is parallel to the thickness direction of the end cover, the first body part is far away from the opening compared with the first opening part, and the thickness of the first opening part is larger than that of the first body part; the end cover is connected with the first wall and seals the opening; wherein 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 the second direction is a, the second direction, the thickness direction of the first wall and the first direction are perpendicular to one another, and a / (t1-t2) is larger than or equal to 120 and smaller than or equal to 6000. According to the technical scheme, the reliability of the battery can be improved.

Description

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 the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their advantages of energy conservation and environmental protection. For electric vehicles, battery technology is an important factor related to their development.

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

[0004] 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.

[0005] This application is achieved through the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a battery cell, which includes a shell. The shell includes a shell and an end cap, the shell has an opening, the shell includes a first wall, the first wall includes a first opening portion and a first body portion distributed in sequence along a first direction, the first direction is parallel to the thickness direction of the end cap, the first 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 body portion, and the end cap is connected to the first opening portion and closes the opening; wherein the maximum thickness of the first opening portion is t1, the thickness of the first body portion is t2, the size 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, and 120≤a / (t1-t2)≤6000 is satisfied.

[0007] 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 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 easy to process and manufacture, 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.

[0008] According to some embodiments of the present application, 400≤a / (t1-t2)≤3000, optionally, 500≤a / (t1-t2)≤2000.

[0009] In the above scheme, 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 can have higher strength, and the battery cell has higher energy density.

[0010] According to some embodiments of the present application, 70 mm ≤ a ≤ 600 mm.

[0011] 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.

[0012] According to some embodiments of the present application, 100 mm ≤ a ≤ 500 mm.

[0013] In the above scheme, compared with 70mm≤a≤600mm, when 100mm≤a≤500mm, the battery cell can have a higher energy density and be easy to process and manufacture.

[0014] According to some embodiments of the present application, the first opening portion includes a first section and a second section that are 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.

[0015] 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 portion between the end cover and the first section, and 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 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 service life and reliability of the battery cell.

[0016] 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.

[0017] In the above solution, the end cover is overlapped on the first step surface, so as to facilitate the positioning of the end cover.

[0018] According to some embodiments of the present application, the shell further includes a second wall, the second wall is disposed adjacent to the first wall, the second wall is 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.

[0019] 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, 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 a larger surface of the battery cell, and the first opening portion is thickened, which can reduce the risk of fatigue cracking of the shell near the welding area of ​​the shell and the end cover.

[0020] According to some embodiments of the present application, the second wall includes a second opening portion and a second main body portion distributed in sequence along the first direction, the second main 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 main body portion.

[0021] In the above scheme, 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.

[0022] 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.

[0023] In the above scheme, 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 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.

[0024] 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 sequentially along the first direction, the maximum thickness of the fourth segment is greater than the thickness of the second main body portion, 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.

[0025] In the above scheme, the third section, the fourth section and the second body are sequentially distributed along the first direction, the end cover is connected to the third section, so that the fourth section is adjacent to the connection between the end cover and the third section, the maximum thickness of the fourth section is greater than the thickness of the second body, and the maximum thickness of the fourth section is greater than the maximum thickness of the third section, so that the second opening has a higher strength, which can reduce the risk of 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. The end cover overlaps the second step surface to facilitate the positioning of the end cover.

[0026] According to some embodiments of the present application, the battery cell further includes an electrode assembly, the electrode assembly is disposed in the housing, 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 cap, 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, 0.3mm 2 ≤h*(t1-t2)≤10mm 2 .

[0027] 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 relatively 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 less influence on the welding area between the shell and the end cover. At the same time, the first opening occupies a smaller space, the space utilization rate in the shell is higher, and the battery cell has a higher energy density.

[0028] According to some embodiments of the present application, 0.4 mm 2 ≤h*(t1-t2)≤7.5mm 2 .

[0029] 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 of ​​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.

[0030] According to some embodiments of the present application, 4.5 mm ≤ h ≤ 20 mm.

[0031] In the above scheme, 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.

[0032] According to some embodiments of the present application, 5mm≤h≤15mm.

[0033] In the above scheme, 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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, the first opening occupies a smaller assembly space and the battery cell has a higher energy density while reducing the difficulty of processing and manufacturing and improving the strength of the first opening.

[0038] 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 main body portion, and the first opening portion exceeds the first surface.

[0039] In the above solution, along the direction from the first body portion to the first opening portion, the first opening portion exceeds the first surface, which can reduce the risk of interference between the first opening portion and the body portion.

[0040] 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 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.

[0041] In the above scheme, the average grain size of the first opening portion other than the welding area is greater 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 between the shell and the end cover.

[0042] 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, a portion of the first opening located below the welding area has a number of grains greater than or equal to 15 in the width direction of the cross-section.

[0043] 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, so that the first opening portion has a higher strength.

[0044] According to some embodiments of the present application, the average grain size of the first opening portion except the welding area ranges from 70 μm to 1200 μm; and / or the average grain size of the first body portion ranges from 30 μm to 1000 μm.

[0045] In the above solution, the average grain size of the first opening portion and / or the average grain size of the first body portion satisfies the above relationship, which is beneficial to enhancing the strength of the first opening portion, so that the first opening portion has higher strength.

[0046] 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.

[0047] 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. 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.

[0048] In the above scheme, the end plate is arranged at the end of multiple battery cells in the third direction, and the end plate has a large connection area with the shell of the adjacent battery cell to form a constraint on the shell and reduce the risk of cracking of the shell near the welding area between the shell and the end cover.

[0049] According to some embodiments of the present application, the end plate is arranged facing the first wall.

[0050] In the above scheme, the end plate is arranged facing the first wall, and has a large contact area with the first main body. During the battery cell charge and discharge cycle, 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.

[0051] 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.

[0052] 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.

[0053] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. 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 related drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0056] Figure 2 An exploded view of a battery provided for some embodiments of the present application;

[0057] Figure 3 An exploded view of a battery cell provided for some embodiments of the present application;

[0058] Figure 4 A schematic diagram of assembling a housing and an electrode assembly provided in some embodiments of the present application;

[0059] Figure 5 for Figure 4 Cross-sectional view in the AA direction;

[0060] Figure 6 for Figure 5 A partial enlarged view of point B;

[0061] Figure 7 A partial schematic diagram of the assembly of a housing and an electrode assembly provided in some embodiments of the present application;

[0062] Figure 8 for Figure 4 The cross-sectional view in CC direction;

[0063] Fig. 9 for Figure 8 A partial enlarged view of point D;

[0064] Fig.10 A cross-sectional view of a portion of the structure after the end cap and the housing are assembled according to some embodiments of the present application;

[0065] Fig.11 A schematic diagram of assembling an end plate and a plurality of battery cells provided in some embodiments of the present application;

[0066] Fig.12 A schematic diagram of the assembly of the end plate and the battery cell provided in an embodiment of the present application;

[0067] Fig.13 for Fig.12 A partial enlarged view of point E.

[0068] Icon: 100-battery; 10-box; 11-first sub-box; 12-second sub-box; 20-battery cell; 21-housing; 211-housing; 212-end cover; 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- The third section; 2141b-the fourth section; 2142-the second main body; 2143-the second step surface; 215-the bottom wall; 210-the welding area; 22-the electrode assembly; 22a-the first surface; 221-the main body; 222-the ear; 23-the electrode terminal; 24-the adapter; 30-the end plate; 200-the controller; 300-the motor; 1000-the vehicle; F1-the first dividing line; F2-the second dividing line; X-the first direction; Y-the second direction; Z-the third direction. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0070] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0071] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0072] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0073] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0074] The term "multiple" as used in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).

[0075] 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.

[0076] 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 accommodated in the case.

[0077] 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.

[0078] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0079] 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.

[0080] 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 storage batteries, etc.

[0081] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0082] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet 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.

[0083] 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 disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0084] 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 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.).

[0085] 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.

[0086] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0087] As an example, the negative 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.

[0088] In some embodiments, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode active material is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0089] As an example, the negative electrode active material may adopt the negative electrode active material for the battery 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 and 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.

[0090] 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 stability and mechanical stability can be selected.

[0091] As an example, the main 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 special restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without special restrictions. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surface of the positive and negative electrodes.

[0092] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0093] 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.

[0094] In some embodiments, the electrode assembly is a laminate structure.

[0095] In some embodiments, the 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 (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0096] In some embodiments, the housing includes an end cap and a shell, the shell is provided with an opening, and the end cap closes the opening to form a closed space for accommodating substances such as the electrode assembly and the electrolyte. The shell may be provided with one or more openings. One or more end caps may also be provided.

[0097] In some embodiments, at least one electrode terminal is disposed on the housing, and the electrode terminal is electrically connected to the electrode tab of the electrode assembly. The electrode terminal may be directly connected to the electrode tab, or may be indirectly connected to the electrode tab through an adapter. The electrode terminal may be disposed on the end cap, or may be disposed on the housing.

[0098] In some embodiments, an explosion-proof valve is provided on the housing, and the explosion-proof valve is used to release the internal pressure of the battery cell.

[0099] 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, a polygonal prismatic battery, and the polygonal prismatic battery is, for example, a hexagonal prismatic battery.

[0100] The development of battery technology must take into account many 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.

[0101] In some embodiments, the battery cell includes an outer shell, which includes a shell and an end cap, the shell has an opening, and the end cap is connected to the shell and closes the opening. The end cap is usually welded to the shell to form a weld mark, but the high temperature when the end cap and the shell are welded easily reduces the strength of the end cap and the shell near the welding position. During the charge and discharge cycle of the battery cell, the shell expands and contracts, which easily leads to fatigue cracking of the shell near the welding area of ​​the shell and the end cap, resulting in damage to the shell, reducing the service life and reliability of the battery cell.

[0102] 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.

[0103] 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 a higher strength, which can reduce the risk of fatigue cracking of the shell near the welding area between 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.

[0104] The battery disclosed in the embodiment of the present application can be used in, but not limited to, electrical equipment such as vehicles, ships or aircraft. The battery disclosed in the present application can be used to form a power supply system of the electrical equipment.

[0105] The embodiment of the present application provides an electric device using a battery as a power source, and 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. Among them, the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0106] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device in an embodiment of the present application.

[0107] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application. Vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000, for the circuit system of the vehicle 1000, for example, for the working power requirements during the startup, navigation and operation of the vehicle 1000.

[0108] The vehicle 1000 may further include a controller 200 and a motor 300 , wherein 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 starting, navigating, and driving the vehicle 1000 .

[0109] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve 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.

[0110] Please refer to Figure 2 , Figure 2 An exploded view of a battery provided for some embodiments of the present application. The battery 100 includes a case 10 and a battery cell 20, and the battery cell 20 is contained in the case 10. Among them, the case 10 is used to provide a storage space for the battery cell 20, and the case 10 can adopt a variety of structures. In some embodiments, the case 10 may include a first sub-case 11 and a second sub-case 12, and the first sub-case 11 and the second sub-case 12 cover each other, and the first sub-case 11 and the second sub-case 12 jointly define a storage space for accommodating the battery cell 20. The second sub-case 12 may be a hollow structure with one end open, and the first sub-case 11 may be a plate-like structure, and the first sub-case 11 covers the open side of the second sub-case 12, so that the first sub-case 11 and the second sub-case 12 jointly define a storage space; the first sub-case 11 and the second sub-case 12 may also be hollow structures with one side open, and the open side of the first sub-case 11 covers the open side of the second sub-case 12.

[0111] 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 mixed connection. A mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.

[0112] 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.

[0113] Please refer to Figure 3 , Figure 3 An exploded view of a battery cell provided in some embodiments of the present application. Figure 3 As shown, the battery cell 20 includes a housing 21, an electrode assembly 22 and other functional components. The housing 21 includes a shell 211 and an end cap 212. The shell 211 has an opening, and the end cap 212 closes the opening to isolate the internal environment of the battery cell 20 from the external environment.

[0114] The shell 211 is a component used to cooperate with the end cap 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, the electrolyte and other components. The shell 211 and the end cap 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.

[0115] 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 and collided, so that the battery cell 20 can have a higher structural strength and 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 a variety of materials, 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, and the insulating structure may be used to isolate the electrical connection components in the housing 211 from the end cap 212 to reduce the risk of short circuit. For example, the insulating structure may be plastic, rubber, or the like.

[0116] The electrode assembly 22 is a component in the battery cell 20 where an electrochemical reaction occurs. One or more electrode assemblies 22 may be included 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, and the separator is used to separate the positive electrode sheet and the negative electrode sheet to avoid 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 pole ear. The positive pole ear and the negative pole ear may be located together at one end of the main body or respectively at both ends of the main body.

[0117] Please refer to Figure 3 , and further refer to Figures 4 to 6 , Figure 4 A schematic diagram of the assembly of a housing and an electrode assembly provided in some embodiments of the present application, Figure 4 The figure shows 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 for Figure 4The cross-sectional view in the AA direction, Figure 6 for Figure 5 A partial enlarged view of point B.

[0118] The embodiment of the present application provides a battery cell 20, which includes a shell 21. The shell 21 includes a shell 211 and an end cover 212. The shell 211 has an opening, and the shell 211 includes a first wall 213. The first wall 213 includes a first opening portion 2131 and a first body portion 2132 distributed in sequence along a first direction X, and the first direction X is parallel to the thickness direction of the end cover 212. The first body portion 2132 is farther away from the opening than the first opening portion 2131, and the thickness of the first opening portion 2131 is greater than the thickness of the first body portion 2132. The end cover 212 is connected to the first opening portion 2131 and closes the opening. Among them, the maximum thickness of the first opening portion 2131 is t1, the thickness of the first body portion 2132 is t2, the size of the first wall 213 in the second direction Y is a, and the second direction Y, the thickness direction of the first wall 213 and the first direction X are perpendicular to each other, satisfying that 120≤a / (t1-t2)≤6000.

[0119] In the figure, the direction indicated by letter X is the first direction, which is parallel to the thickness direction of the end cover 212. The direction indicated by letter Y is the second direction, which can be parallel to the length direction of the battery cell 20, or the width direction of the battery cell 20.

[0120] Along the first direction X, the first body portion 2132 is farther away from the opening than the first opening portion 2131 , and the first opening portion 2131 may be surrounded to form an opening.

[0121] In some embodiments, the end cap 212 may be welded to the first wall 213 to form a first welding zone, and a portion of the first opening 2131 may be welded to the end cap 212 to form a first welding zone. In some embodiments, the first welding zone may be referred to as a weld mark.

[0122] In some embodiments, the first body portion 2132 may be a structure of uniform thickness, 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 be a structure of uniform thickness or a structure of variable thickness; when the first opening portion 2131 is a structure of uniform thickness, 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 is a structure of variable thickness, the maximum thickness of the first opening portion 2131 may be the thickness at the position of the maximum thickness of the first opening portion 2131.

[0123] Optionally, when the first opening portion 2131 is a thickened structure, the thickness of the first opening portion 2131 can gradually decrease from an end away from the first main body portion 2132 toward an 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.

[0124] The larger the size of the first wall 213 in the second direction Y is, 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 .

[0125] The smaller the difference between the maximum thickness of the first opening portion 2131 and the thickness of the first main body portion 2132 is, 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 is, the larger the assembly space occupied by the first opening portion 2131 is, which affects the energy density of the battery cell 20.

[0126] 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 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 a 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, thereby improving 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.

[0127] 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.

[0128] 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.

[0129] 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 portion 2131 may protrude from the second surface.

[0130] 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.

[0131] In some embodiments, the first opening portion 2131 can be separately provided or integrally formed. For example, during the manufacturing process of the shell 211, at the opening of the first wall 213, the thickened portion and the base of the first wall 213 are separately provided, the thickened portion and the base are fixedly connected to form the first opening portion 2131, and the base forms the first body portion 2132 in the area of ​​the first wall 213 in the first body portion 2132; for another example, during the manufacturing process of the shell 211, the shell 211 can be stamped, the shell 211 is an integrally formed structure, the first opening portion 2131 is formed 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.

[0132] Figure 6 The dotted line indicated by the letter F1 in FIG. 2 may be a boundary line between the first opening portion 2131 and the first body portion 2132 . For the convenience of distinction, the boundary line may be a first boundary line F1 .

[0133] In some embodiments, due to the thickness difference between the first opening portion 2131 and the first body portion 2132, when part of the first opening portion 2131 protrudes from the first surface, a groove 2130 is formed between the first opening portion 2131 and the first surface of the first body portion 2132, and the body portion 221 of the electrode assembly 22 may be disposed in the groove 2130, or the body portion 221 may not be in the groove 2130. It should be noted that the groove 2130 is a concave area formed by the height difference between the first opening portion 2131 and the first body portion 2132.

[0134] According to some embodiments of the present application, 400≤a / (t1-t2)≤3000, optionally, 500≤a / (t1-t2)≤2000.

[0135] 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.

[0136] 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.

[0137] According to some embodiments of the present application, 70 mm ≤ a ≤ 600 mm.

[0138] a can be any value between 70 mm and 600 mm. Optionally, 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.

[0139] 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.

[0140] According to some embodiments of the present application, 100 mm ≤ a ≤ 500 mm.

[0141] 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 easy to process and manufacture.

[0142] Optionally, a can be but is not limited to 100mm, 150mm, 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, etc.

[0143] Please refer to Figure 7 , Figure 7 A partial schematic diagram of the assembly of a housing and an electrode assembly provided in some embodiments of the present application, Figure 7 The first opening portion 2131 includes a first section 2131a and a second section 2131b connected to each other, the first section 2131a, the second section 2131b and the first body portion 2132 are sequentially distributed 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, and the end cap 212 (please refer to Figure 3 ) is connected to the first section 2131a.

[0144] 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.

[0145] 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 a higher strength.

[0146] In some embodiments, 0.1 mm≤t1-t3≤0.2 mm.

[0147] In some embodiments, 0.4 mm ≤ t3 ≤ 3.9 mm.

[0148] Optionally, t3 may be, but is not limited to, 0.4mm, 0.6mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 3.9mm, etc.

[0149] 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.

[0150] 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 position 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, and the maximum thickness of the second section 2131b is greater than the maximum thickness of the first section 2131a, so that the first opening portion 2131 has a 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 service life and reliability of the battery cell 20.

[0151] In some embodiments, before the first section 2131a is connected to the end cap 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 cap 212 and the first section 2131a.

[0152] In some embodiments, before the first section 2131a is connected to the end cap 212, the maximum thickness of the housing 211 in the area 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 be an equal thickness structure. After the first opening 2131 is welded to the end cap 212, a portion of the housing 211 in the area where the first section 2131a is located is welded to a portion of the end cap 212 to form a first welded area, and the remaining portion is referred to as the first section 2131a.

[0153] 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 .

[0154] 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, and a first step surface 2133 is formed between the second section 2131b and the first section 2131a. The end cover 212 overlaps the first step surface 2133 to facilitate the positioning of the end cover 212.

[0155] Please refer to Figure 3 and Figure 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, and the second wall 214 is connected to the end cover 212, and the area of ​​the outer surface of the first wall 213 is greater than the area of ​​the outer surface of the second wall 214.

[0156] The second wall 214 is adjacent to the first wall 213 , and the second wall 214 is adjacent to the end cover 212 , and the second wall 214 and the first wall 213 together form an opening.

[0157] In some embodiments, the number of the 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 the 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.

[0158] 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. The first wall 213 may be a wall of the shell 211 with a larger area. For example, the area of ​​the outer surface of the first wall 213 may be larger than the area of ​​the outer surface of the end cover 212. The first wall 213 may be a large surface of the battery cell 20. During the charge and discharge cycle of the battery cell 20, the first wall 213 is subjected to a large force. The first opening 2131 of the first wall 213 is thickened to improve the strength of the first opening 2131, so as to reduce the risk of fatigue cracking of the shell 211 near the welding area of ​​the shell 211 and the end cover 212.

[0159] Please refer to Figure 8 , Figure 8 for 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 opening than 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.

[0160] Fig. 9 The dotted line indicated by the letter F2 may be a boundary line between the second opening portion 2141 and the second body portion 2142 . For the convenience of distinction, the boundary line may be a second boundary line F2 .

[0161] 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.

[0162] In some embodiments, a portion of the second opening portion 2141 may be welded to the end cover 212 to form a second welding zone. In some embodiments, the second welding zone may be referred to as a welding mark.

[0163] In some embodiments, the second body portion 2142 may be 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 be a uniform thickness structure or a variable thickness structure; when the second opening portion 2141 is 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 is a variable thickness structure, the maximum thickness of the second opening portion 2141 may be the thickness at the position where the thickness of the second opening portion 2141 is the maximum.

[0164] Optionally, when the second opening portion 2141 is a thickened structure, the thickness of the second opening portion 2141 can gradually decrease from an end away from the second main body portion 2142 toward an 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.

[0165] In the above scheme, 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.

[0166] Please refer to Figure 4 According to some embodiments of the present application, the dimension of the second wall 214 in the third direction Z is b, and the third direction Z, the second direction Y and the first direction X are perpendicular to each other, satisfying 40 mm ≤ b.

[0167] When the size of the second wall 214 in the third direction Z is small, the second wall 214 is not easy to crack during the charging and discharging process of the battery cell 20. When the size of the second wall 214 in the third direction Z is large, the second opening 2141 and the first opening 2131 need to be thickened, and the processing and manufacturing of the shell 211 is more difficult.

[0168] 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 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.

[0169] Optionally, 40mm≤b≤120mm.

[0170] Optionally, b can be any value between 40 mm and 120 mm. Optionally, b can be but 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.

[0171] 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 .

[0172] Please refer to Figure 8 , and further refer to Fig. 9 , Fig. 9 for Figure 8According to some embodiments of the present application, the second opening portion 2141 includes a third section 2141a and a fourth section 2141b 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, 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, and the end cover 212 (please refer to Figure 3 ) overlaps the second step surface 2143 and is connected to the third section 2141a.

[0173] 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 .

[0174] 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 a higher strength.

[0175] Since the second wall 214 is the side of the battery cell 20, during the manufacturing process of the battery cell 20, the shell 211 is usually thinned in the area of ​​the third section 2141a so that the maximum thickness of the area is less than the thickness of the second body part 2142, so as to facilitate the welding of the second wall 214 and the end cover 212. In some embodiments of the present application, before the third section 2141a is connected to the end cover 212, the shell 211 in the area of ​​the third section 2141a can be thickened so that the maximum thickness of the shell 211 in the area of ​​the third section 2141a can be greater than or equal to the thickness of the second body part 2142, so as to improve the connection firmness between the end cover 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 may be thickened, and the maximum thickness of the area of ​​the shell 211 in the third section 2141a may 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.

[0176] 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.

[0177] 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 on the second step surface 2143 to achieve positioning of the end cover 212 .

[0178] 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 position 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, and 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 a 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 is in thermal runaway or the gas production is too large, thereby improving the service life and reliability of the battery cell 20.

[0179] Please refer to Figure 3 and Figure 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 number of the second wall 214 are both two, the two first walls 213 are relatively arranged along the third direction Z, the two second walls 214 are relatively arranged along the second direction Y, the two first walls 213 and the two second walls 214 are surrounded by the bottom wall 215, the two first walls 213 and the two second walls 214 are integrally formed with the bottom wall 215, and the bottom wall 215 and the end cover 212 are relatively arranged in the first direction X.

[0180] Please refer to Figure 3 , and further refer to Fig.10 , Fig.10 A cross-sectional view of a partial structure after the end cap and the shell are assembled in 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, and the electrode assembly 22 includes a main body 221, the main body 221 has a first surface 22a facing the end cap 212, and the end cap 212 has a second surface 2121 facing away from the inside 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 .

[0181] In some embodiments, the electrode assembly 22 further includes a tab 222 extending from the main body 221 , and the tab 222 may extend from the first surface 22 a .

[0182] The second surface 2121 may be an outer surface of the end cover 212 .

[0183] 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 high energy density.

[0184] h*(t1-t2) can be 0.3mm 2 With 10mm 2 Optionally, h*(t1-t2) can be, but is not limited to, 0.3 mm. 2 , 0.5mm 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 , 8mm 2 , 8.5mm 2 , 9mm 2 、9.5mm 2 , 10mm 2 wait.

[0185] According to some embodiments of the present application, 0.4 mm 2 ≤h*(t1-t2)≤7.5mm 2 .

[0186] 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 , 2.5mm2 , 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.

[0187] In the above scheme, compared with 0.3mm 2 ≤h*(t1-t2), when 0.4mm 2 ≤h*(t1-t2), 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 of ​​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.

[0188] According to some embodiments of the present application, 4mm≤h≤20mm.

[0189] h can be any value between 4.5 mm and 20 mm. Optionally, h can be, but is not limited to, 4 mm, 4.5 mm, 5.5 mm, 6.5 mm, 7.5 mm, 8.5 mm, 9.5 mm, 10.5 mm, 11.5 mm, 12.5 mm, 13.5 mm, 14.5 mm, 15.5 mm, 16.5 mm, 17.5 mm, 18.5 mm, 19.5 mm, 20 mm, etc.

[0190] 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.

[0191] According to some embodiments of the present application, 4.5 mm ≤ h ≤ 15 mm.

[0192] Optionally, h can be but is not limited to 4.5mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, etc.

[0193] In the above scheme, 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.

[0194] 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.

[0195] 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 manufacture and has high strength. The first opening portion 2131 occupies a small assembly space, and the battery cell 20 has a high energy density.

[0196] t1 may be any value between 0.5 mm and 4 mm. Optionally, t1 may 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.

[0197] t2 may be any value between 0.4 mm and 2 mm. Optionally, t2 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, 1.9 mm, 2 mm, etc.

[0198] t1-t2 may be any value between 0.1 mm and 2 mm. Optionally, t1-t2 may 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.

[0199] 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.

[0200] 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, and the first opening portion 2131 occupies a smaller assembly space while reducing the difficulty of processing and manufacturing and improving the strength of the first opening portion 2131, and the battery cell 20 has a higher energy density.

[0201] 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.

[0202] Optionally, 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.

[0203] 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.

[0204] According to some embodiments of the present application, t4 satisfies: 0.5mm≤t4≤5mm.

[0205] 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.

[0206] Optionally, 0.9mm≤t4≤2.2mm.

[0207] 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.

[0208] According to some embodiments of the present application, t5 satisfies: 0.4mm≤t5≤3mm.

[0209] 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.

[0210] Optionally, 0.7mm≤t5≤1.2mm.

[0211] 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.

[0212] According to some embodiments of the present application, t6 satisfies: 0.1 mm≤t4-t6≤0.2 mm.

[0213] 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 2131 is pointed along the first main body 2132, and the first opening 2131 exceeds the first surface 22a.

[0214] When viewed along the thickness direction of the first wall 213 , the first opening 2131 does not overlap with the main body 221 .

[0215] In the above solution, along the direction from the first body portion 2132 to the first opening portion 2131 , the first opening portion 2131 exceeds the first surface 22 a , which can reduce the risk of interference between the first opening portion 2131 and the body portion 221 .

[0216] In some embodiments, along the direction from the second body portion 2142 to the second opening portion 2141 , the second opening portion 2141 exceeds the first surface 22 a .

[0217] When viewed along the thickness direction of the first wall 213 , the second opening 2141 does not overlap with the main body 221 .

[0218] In the above solution, along the direction from the second body portion 2142 to the second opening portion 2141 , the second opening portion 2141 exceeds the first surface 22 a , which can reduce the risk of interference between the second opening portion 2141 and the body portion 221 .

[0219] Please refer to Fig.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, and the average grain size 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, and the average grain size is the average grain size of the grains in the thickness direction of the first wall 213.

[0220] 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 may be referred to as a weld mark.

[0221] The thickness direction of the first wall 213 may be parallel to the Z direction.

[0222] 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 / T13298-2017 "Electron rear-view microscope method for determination of grain size of metal materials".

[0223] In the above scheme, the average grain size of the first opening portion 2131 other than the welding area 210 is greater 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, reducing the risk of cracking of the shell 211 near the welding area 210 of the shell 211 and the end cover 212.

[0224] 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 , in a portion of the first opening 2131 located below the welding region 210 , the number of grains in the width direction of the cross-section is greater than or equal to 15.

[0225] The width direction of the cross section may be parallel to the Z direction.

[0226] “The portion of the first opening 2131 located below the welding region 210” means, Fig.10 In the X-direction, in the direction in which the first opening portion 2131 points to the first main body portion 2132, the portion of the first opening portion 2131 located below the welding area 210, that is, along the direction in which the first opening portion 2131 points to the first main body portion 2132, the portion of the first opening portion 2131 located away from the welding area 210.

[0227] 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.

[0228] According to some embodiments of the present application, the average grain size of the first opening portion 2131 except the welding region 210 is in the range of 70 μm-1200 μm; and / or the average grain size of the first body portion 2132 is in the range of 30 μm-1000 μm.

[0229] Optionally, the average grain size of the first opening 2131 excluding 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.

[0230] 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.

[0231] 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 satisfies 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.

[0232] According to some embodiments of the present application, the average grain size of the second opening portion 2141 except the welding area 210 is greater than the average grain size of the second body portion 2142 , and the average grain size is the average grain size of the grains in the thickness direction of the second wall 214 .

[0233] In the above scheme, the average grain size of the second opening portion 2141 other than the welding area 210 is greater 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.

[0234] 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.

[0235] The width direction of the cross section is parallel to the Y direction.

[0236] “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.

[0237] 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.

[0238] According to some embodiments of the present application, the average grain size of the second opening portion 2141 except the welding region 210 is in the range of 70 μm-1200 μm; and / or the average grain size of the second body portion 2142 is in the range of 30 μm-1000 μm.

[0239] Optionally, the average grain size of the second opening portion 2141 excluding the welding area 210 may be but is not limited to 70μm, 80μm, 90μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, 1100μm, 1200μm, etc.

[0240] 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.

[0241] 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.

[0242] According to some embodiments of the present application, the shell 211 is a prismatic structure with openings at both ends, and the number of the end covers 212 is two, and the two end covers 212 respectively close the two openings.

[0243] When the housing 211 is a prism-shaped 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.

[0244] 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.

[0245] 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 cracking of the shell 211 near the welding area between the shell 211 and the end cover 212 .

[0246] 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.

[0247] Please refer to Figures 11 to 13 , Fig.11 This is a schematic diagram of assembling an end plate and a plurality of battery cells provided in some embodiments of the present application. Fig.12 This is a schematic diagram of the assembly of the end plate and the battery cell provided in the embodiment of the present application. Fig.13 for Fig.12 A partial enlarged view of point E.

[0248] According to some embodiments of the present application, the number of battery cells 20 is multiple, and the multiple battery cells 20 are stacked along a 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 of 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.

[0249] 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 to restrain the deformation of the battery cells 20.

[0250] 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 larger 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.

[0251] According to some embodiments of the present application, the end plate 30 is disposed facing the first wall 213 .

[0252] 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 portion 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.

[0253] According to some embodiments of the present application, an electrical device is provided, and the electrical device includes a battery cell 20 or a battery 100 provided in any one of the above embodiments.

[0254] 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.

[0255] 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 provided in any one of the above embodiments.

[0256] According to some embodiments of this application, please refer to Figures 3 to 10 The embodiment of the present application provides a battery cell 20, which is a rectangular parallelepiped. The battery cell 20 includes a shell 21, an electrode assembly 22 and an electrode terminal 23. The electrode assembly 22 is arranged in the shell 21. The shell 21 includes a shell 211 and an end cover 212. The electrode terminal 23 is arranged on the end cover 212. The electrode terminal 23 is connected to the pole ear 222 of the electrode assembly 22 through an adapter 24. The shell 211 has an opening. The shell 211 includes two first walls 213 arranged oppositely along the third direction Z, two second walls 214 arranged oppositely 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. 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 oppositely in the first direction X. The end cover 212 is connected to the first wall 213 and the second wall 214 to close the opening.

[0257] 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, and the thickness of the first main body portion 2132 is t2. The dimension of the first wall 213 in the second direction Y is a, satisfying 120≤a / (t1-t2)≤6000.

[0258] The second wall 214 includes a second opening portion 2141 and a second body portion 2142 distributed in sequence along the first direction X. The second body portion 2142 is farther from the opening than the second opening portion 2141. The second opening portion 2141 includes a third section 2141a and a fourth section 2141b connected to each other. The third section 2141a, the fourth section 2141b and the second body portion 2142 are distributed in sequence along the first direction X. The end cover 212 is connected to the third section 2141a. The maximum thickness of the fourth section 2141b is greater than the thickness of the second body portion 2142. 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 overlaps the second step surface 2143.

[0259] 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 easy to process and manufacture, and the first opening portion 2131 can have a 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, thereby improving 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 the end cover 212 is welded to 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, 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 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.

[0260] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: A housing, comprising a shell and an end cover, wherein the shell has an opening, the shell comprises a first wall, the first wall comprises a first opening portion and a first body portion sequentially distributed along a first direction, the first direction is parallel to a thickness direction of the end cover, the first 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 body portion, and the end cover is connected to the first opening portion and closes the opening; Among them, the maximum thickness of the first opening portion is t1, the thickness of the first main body portion is t2, the size 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)≤6000.

2. The battery cell according to claim 1, characterized in that: 400≤a / (t1-t2)≤3000, optionally, 500≤a / (t1-t2)≤2000.

3. The battery cell according to claim 1, characterized in that: 70mm≤a≤600mm.

4. The battery cell according to claim 1, characterized in that: 100mm≤a≤500mm.

5. The battery cell according to claim 1, characterized in that: 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 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, 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.

6. The battery cell according to claim 5, characterized in that: A first step surface is formed between the second section and the first section, and the end cover is overlapped on the first step surface.

7. The battery cell according to claim 1, characterized in that: The shell further includes a second wall, the second wall is disposed adjacent to the first wall, the second wall is connected to the end cover, and an area of ​​an outer surface of the first wall is greater than an area of ​​an outer surface of the second wall.

8. The battery cell according to claim 7, characterized in that: The second wall includes a second opening portion and a second body portion sequentially distributed 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.

9. The battery cell according to claim 8, characterized in that: The 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.

10. The battery cell according to claim 8, characterized in that: The second opening portion includes a third section and a fourth section that are connected to each other. The third section, the fourth section and the second main body are distributed in sequence along the first direction. The maximum thickness of the fourth section is greater than the thickness of the second main body. The maximum thickness of the fourth section is greater than the maximum thickness of the third section. A second step surface is formed between the fourth section and the third section. The end cover overlaps the second step surface and is connected to the third section.

11. The battery cell according to claim 1, characterized in that: The battery cell also includes an electrode assembly, which is arranged in the shell, and the electrode assembly includes a main body, and the main body is provided with an active material. The main body has a first surface facing the end cover, and the end cover has a second surface away from the interior of the battery cell. Along the thickness direction of the end cover, the distance between the first surface and the second surface is h, which satisfies, 0.3mm 2 ≤h*(t1-t2)≤10mm 2 .

12. The battery cell according to claim 11, characterized in that: 0.4mm 2 ≤h*(t1-t2)≤7.5mm 2 。 13. The battery cell according to claim 11, characterized in that: 4mm≤h≤20mm.

14. The battery cell according to claim 13, characterized in that: 4.5mm≤h≤15mm.

15. The battery cell according to any one of claims 1 to 14, characterized in that: t1 and t2 meet at least one of the following conditions: (1) 0.1mm≤t1-t2≤2mm; (2) 0.5 mm ≤ t1 ≤ 4 mm; (3)0.4mm≤t2≤2mm.

16. The battery cell according to claim 15, characterized in that: t1 and t2 meet at least one of the following conditions: (1) 0.2mm≤t1-t2≤1mm; (2) 0.7mm≤t1≤2mm; (3)0.4mm≤t2≤1mm.

17. The battery cell according to claim 1, characterized in that: The battery cell further includes an electrode assembly, which includes a main body, the main body is provided with an active material, the main body has a first surface facing the end cover, and the first opening is beyond the first surface along the direction of the first main body pointing to the first opening.

18. The battery cell according to claim 1, characterized in that: The shell and the end cover are welded to form a welding area, and the average grain size of the first opening portion except the welding area is larger 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, characterized in that: In a cross section of the first wall parallel to the thickness direction of the first wall, in a portion of the first opening below the welding region, the number of grains in the width direction of the cross section is greater than or equal to 15.

20. The battery cell according to claim 18, characterized in that: The average grain size of the first opening portion except the welding area is in the range of 70 μm to 1200 μm; and / or the average grain size of the first body portion is in the range of 30 μm to 1000 μm.

21. A battery, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 20.

22. The battery according to claim 21, characterized in that The number of the battery cells is multiple, 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. 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.

23. The battery according to claim 22, characterized in that The end plate is disposed facing the first wall.

24. An electrical equipment, characterized in that: The invention comprises a battery cell according to any one of claims 1 to 20 or a battery according to any one of claims 21 to 23, wherein the battery cell or the battery is used to provide electrical energy.

25. An energy storage device, characterized in that: The method comprises a battery cell as claimed in any one of claims 1 to 20 or a battery as claimed in any one of claims 21 to 23.

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