Battery monomer, battery device and electric device

Abstract

The utility model provides a battery monomer, a battery device and a power utilization device. The battery cell comprises a shell, an electrode assembly and a pressure relief mechanism. The shell is provided with a first wall, and the material of the first wall comprises steel. The electrode assembly is housed within the housing. The pressure relief mechanism is arranged on the first wall and connected with the first wall in a welded mode, the pressure relief mechanism is provided with a weak part, and the weak part is configured to be at least partially damaged when the internal pressure of the shell reaches a threshold value so as to relieve the internal pressure of the shell. Wherein the first wall comprises at least one buffer part, and the buffer part is arranged around the pressure relief mechanism. The buffer part can absorb at least one part of welding stress generated by welding of the pressure relief mechanism and the first wall, so that the risk that the weak part of the pressure relief mechanism is damaged in advance in a normal cycle period under the influence of the welding stress is reduced, the service life of the pressure relief mechanism is prolonged, and the service life of the battery monomer is further prolonged.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a battery cell, a battery device, and an electrical device. Background Technology

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

[0003] In battery technology, pressure relief mechanisms can be incorporated into individual battery cells to release pressure and improve cell reliability. Currently, however, these mechanisms are prone to premature failure within normal cycle times, impacting the lifespan of the battery cell. Utility Model Content

[0004] This application provides a battery cell, a battery device, and an electrical device, which can effectively reduce the risk of the pressure relief mechanism being damaged prematurely within the normal cycle.

[0005] In a first aspect, embodiments of this application provide a battery cell including a casing, an electrode assembly, and a pressure relief mechanism; the casing has a first wall, the material of which includes steel; the electrode assembly is housed within the casing; the pressure relief mechanism is disposed on the first wall and welded to the first wall, the pressure relief mechanism having a weak portion, the weak portion being configured to be at least partially destroyed when the internal pressure of the casing reaches a threshold, so as to release the internal pressure of the casing; wherein, the first wall includes at least one buffer portion, the buffer portion being disposed around the pressure relief mechanism.

[0006] In the above technical solution, the first wall includes a buffer portion surrounding the pressure relief mechanism. The buffer portion can absorb at least a portion of the welding stress generated by welding the pressure relief mechanism to the first wall, reducing the risk that the weak part of the pressure relief mechanism will be damaged prematurely within the normal cycle under the influence of welding stress, thereby improving the service life of the pressure relief mechanism and thus improving the service life of the battery cell.

[0007] In some embodiments, the first wall is provided with a groove, and a buffer portion is formed in the area where the groove is provided on the first wall. By forming the buffer portion by providing a groove on the first wall, the forming method of the buffer portion is simplified and the forming difficulty of the buffer portion is reduced.

[0008] In some embodiments, the electrode assembly is disposed on one side of the first wall along a first direction. Along the first direction, the first wall has a first surface and a second surface disposed opposite to each other. At least one buffer portion protrudes from the first surface, and a groove corresponding to the buffer portion protruding from the first surface is formed on the second surface. For the buffer portion protruding from the first surface, the buffer portion can occupy more space in the first direction, which is beneficial to increase the thickness of the buffer portion and reduce the setting of the groove, thereby reducing the influence of excessive thickness of the buffer portion on the strength of the first wall. The groove is provided on the second surface, and the buffer portion corresponding to the groove protrudes from the first surface. This structure allows the buffer portion protruding from the first surface to be in a bent state, giving the buffer portion better deformation capability. The buffer portion has a better absorption effect on the welding stress generated by welding the pressure relief mechanism to the first wall, further reducing the influence of welding stress on the weak part of the pressure relief mechanism. On the other hand, the buffer portion protruding from the first surface enhances the ability of the first wall to resist deformation.

[0009] In some embodiments, along the first direction, the deepest position of the groove formed on the second surface is farther away from the second surface than the first surface. This structure increases the depth of the groove formed on the second surface, which is beneficial to increasing the curvature of the buffer portion protruding from the first surface, and further enhancing the absorption effect of the buffer portion on the welding stress generated by the welding of the pressure relief mechanism and the first wall.

[0010] In some embodiments, the first wall includes a plurality of buffer portions, all of which are arranged around the pressure relief mechanism; at least one buffer portion protrudes from the second surface, and a groove corresponding to the buffer portion protruding from the second surface is formed on the first surface. The first wall includes a plurality of buffer portions, all of which are arranged around the pressure relief mechanism. These buffer portions can absorb the welding stress generated by welding the pressure relief mechanism to the first wall, further reducing the impact of welding stress on the weak parts of the pressure relief mechanism. For the buffer portion protruding from the second surface, the buffer portion can occupy more space in the first direction, which is beneficial for increasing the thickness of the buffer portion and reducing the amount of groove, thus reducing the impact of excessive thickness of the buffer portion on the strength of the first wall. By providing a groove on the first surface and having the corresponding buffer portion protrude from the second surface, this structure allows the buffer portion protruding from the second surface to be in a bent state, giving it better deformation capability and better absorption of the welding stress generated by welding the pressure relief mechanism to the first wall, further reducing the impact of welding stress on the weak parts of the pressure relief mechanism. Furthermore, it enhances the ability of the buffer portion protruding from the second surface to resist deformation of the first wall. In addition, since the first wall includes both a buffer portion protruding from the first surface and a buffer portion protruding from the second surface, on the one hand, the direction of the forming force on the first wall when forming the buffer portion protruding from the first surface is opposite to the direction of the forming force on the first wall when forming the buffer portion protruding from the second surface, which is beneficial to reduce the deformation of other areas of the first wall except for the buffer portion; on the other hand, compared with a structure in which all buffer portions protrude from the first surface, the deformation resistance of the first wall can be increased.

[0011] In some embodiments, along the first direction, the deepest position of the groove formed on the first surface is farther away from the first surface than the second surface. This structure increases the depth of the groove formed on the first surface, which is beneficial to increasing the curvature of the buffer portion protruding from the second surface, and further enhances the absorption effect of the buffer portion on the welding stress generated by the welding of the pressure relief mechanism and the first wall.

[0012] In some embodiments, the first surface faces the electrode assembly. This structure causes the buffer portion protruding from the first surface to protrude into the interior of the housing, reducing the space occupied by the buffer portion in the external space of the housing. This helps to reduce the possibility of interference or collision between the buffer portion and external components, thereby reducing the risk that the weak part of the pressure relief mechanism will be prematurely damaged by the impact force of external components on the buffer portion.

[0013] In some embodiments, the first wall and the pressure relief mechanism are connected by a welded part. Along the width direction of the groove, the minimum distance between the groove closest to the welded part and the welded part is L, where 1mm ≤ L ≤ 10mm. L ≥ 1mm ensures sufficient distance between the groove closest to the welded part and the welded part, reducing the impact of welding the pressure relief mechanism to the first wall on the buffer part closest to the welded part and reducing the welding difficulty between the pressure relief mechanism and the first wall. L ≤ 10mm prevents the distance between the groove closest to the welded part from being too large, freeing up more space on the first wall for installing the pressure relief mechanism. This allows for the installation of a larger pressure relief mechanism on the first wall, thereby improving the pressure relief capacity of the battery cell.

[0014] In some embodiments, 3mm ≤ L ≤ 7mm. L ≥ 3mm further increases the distance between the groove closest to the weld and the weld, further reducing the welding difficulty between the pressure relief mechanism and the first wall. L ≤ 7mm allows for a further increase in the size of the pressure relief mechanism on the first wall, enabling large-area pressure relief.

[0015] In some embodiments, the minimum width of the groove opening is W, where 0.8mm ≤ W ≤ 8mm. W ≥ 0.8mm reduces the difficulty of forming the groove. W ≤ 8mm reduces the space occupied by the groove on the first wall, thus freeing up more space on the first wall for the pressure relief mechanism.

[0016] In some embodiments, 1.5mm ≤ W ≤ 5mm. W ≥ 1.5mm further reduces the difficulty of forming the groove. W ≤ 5mm further reduces the space occupied by the groove on the first wall.

[0017] In some embodiments, the first wall further includes a wall body connected to the buffer section. The wall body is welded to the pressure relief mechanism. The thickness of the wall body is D, and the depth of the groove is H, where H > D. The depth of the groove is greater than or equal to the thickness of the wall body, which increases the depth of the groove. This increases the curvature of the buffer section and further enhances the absorption effect of the buffer section on the welding stress generated by the welding of the pressure relief mechanism and the first wall.

[0018] In some embodiments, 0.6mm ≤ H ≤ 3mm. H ≥ 0.6mm reduces the difficulty of forming the groove and ensures the buffer portion has good deformability, enhancing its absorption of welding stress generated during the welding of the pressure relief mechanism to the first wall. H ≤ 3mm prevents the groove depth from becoming excessive, reducing the forming force on the first wall during groove formation and lowering the risk of damage to the first wall during the process.

[0019] In some embodiments, 0.8mm ≤ H ≤ 1.5mm. H ≥ 0.8mm further reduces the difficulty of forming the groove and enhances the absorption effect of the buffer portion on the welding stress generated by the welding of the pressure relief mechanism and the first wall. H ≤ 1.5mm further reduces the risk of the first wall being damaged during the groove forming process.

[0020] In some embodiments, the groove is formed by stamping on the first wall. The groove is formed on the first wall by stamping, which is a simple forming method.

[0021] In some embodiments, the first wall includes a plurality of buffer portions, all of which are arranged around the pressure relief mechanism. These buffer portions can absorb welding stress generated during the welding of the pressure relief mechanism to the first wall, further reducing the impact of welding stress on the weak points of the pressure relief mechanism.

[0022] In some embodiments, the buffer portion is bent in a plane perpendicular to its extension direction. The bent buffer portion has better deformability, thereby enhancing its buffering capacity and its absorption of welding stress generated during the welding of the pressure relief mechanism to the first wall.

[0023] In some embodiments, at least a portion of the buffer portion is arc-shaped in a plane perpendicular to its extension direction. The arc-shaped portion of the buffer portion has a smoother transition in the plane perpendicular to its extension direction, which reduces the likelihood of stress concentration in the buffer portion, thereby reducing the risk of strength reduction due to stress concentration. Furthermore, it gives the buffer portion better deformation and recovery capabilities, further enhancing its buffering capacity.

[0024] In some embodiments, the electrode assembly is disposed on one side of the first wall along a first direction. The battery cell also includes a connector. Along the first direction, a portion of the first wall and a portion of the pressure relief mechanism are both located on the same side of the connector and are connected by a welded portion. The welded portion connects the connector. The connector reduces the welding difficulty between the first wall and the pressure relief mechanism, reduces the risk of the first wall and / or the pressure relief mechanism being welded through, and improves the welding quality between the first wall and the pressure relief mechanism.

[0025] In some embodiments, the first wall is provided with a groove, and a buffer portion is correspondingly formed in the area where the groove is provided. Along the first direction, the first wall has a first surface and a second surface disposed opposite to each other, at least one buffer portion protrudes from the first surface, and the groove opening corresponding to the buffer portion protruding from the first surface is formed on the second surface. A connector is disposed on the first surface. Since the connector is disposed on the first surface, for the buffer portion protruding from the first surface, the buffer portion and the connector can share the space on the same side of the first wall along the first direction, making the overall structure of the first wall and the connector more compact in the first direction.

[0026] In some embodiments, along a first direction, the connector has a third surface facing away from the first surface, and along the direction from the first surface to the third surface, the buffer portion protruding from the first surface does not extend beyond the third surface. This structure allows the connector to provide a certain degree of protection for the buffer portion. After other components come into contact with the third surface, they will be unable to continue moving towards the first surface, thereby reducing the risk of other components colliding with the buffer portion and affecting its buffering capacity.

[0027] In some embodiments, the orthographic projection of the connector overlaps the orthographic projection of the weld in a projection plane perpendicular to the first direction. This structure increases the area of ​​the interface between the weld and the connector, thereby improving the welding strength between the pressure relief mechanism and the first wall.

[0028] In some embodiments, the pressure relief mechanism includes an edge portion, a recess, and a protrusion. The edge portion is connected to the first wall via a welded portion. Along a first direction, the edge portion has a fourth surface and a fifth surface disposed opposite to each other. The recess is recessed from the fifth surface in a direction pointing from the fifth surface to the fourth surface. The protrusion is disposed corresponding to the recess and protrudes from the fourth surface, and a weak portion is formed on the protrusion. A connector is disposed on the fourth surface. The recess, which is recessed from the fifth surface of the edge portion in a direction pointing from the fifth surface to the fourth surface, and the protrusion with the weak portion, which is disposed corresponding to the recess and protrudes from the fourth surface, provides better resistance to deformation and reduces the impact of battery cell breathing on the weak portion, thereby reducing the risk of fatigue cracking in the weak portion. Furthermore, since the connector is disposed on the fourth surface, the protrusion and the connector can share the space on the same side of the first wall along the first direction, making the pressure relief mechanism and the overall structure of the first wall more compact in the first direction.

[0029] In some embodiments, along the first direction, the connector has a third surface facing away from the fourth surface, and the protrusion does not extend beyond the third surface in the direction pointing from the fourth surface to the third surface. This structure allows the connector to provide some protection for the protrusion, preventing other components from continuing to move closer to the fourth surface after contacting the third surface, thereby reducing the risk of other components colliding with the protrusion and causing premature damage to the weak part.

[0030] In some embodiments, the protrusion includes a sidewall and a bottom wall, the sidewall connecting the bottom wall and an edge portion, the edge portion surrounding the sidewall, the sidewall surrounding the bottom wall, the sidewall protruding from a fourth surface, and a weak portion formed in the bottom wall. This structure can reduce the molding difficulty of the weak portion in the protrusion.

[0031] In some embodiments, at least a portion of the bottom wall protrudes in a direction from the fourth surface to the fifth surface to form a raised portion. This raised portion, protruding in a direction from the fourth surface to the fifth surface, effectively utilizes the space inside the sidewall and improves the bottom wall's resistance to deformation, reducing the impact of cell breathing on weak points and thus lowering the risk of fatigue cracking in weak points.

[0032] In some embodiments, the raised portion does not extend beyond the fifth surface in the direction from the fourth surface to the fifth surface. After other components come into contact with the fifth surface, they will be unable to continue moving towards the raised portion, thereby reducing the risk of other components colliding with the raised portion and causing premature damage to the weak portion.

[0033] In some embodiments, the fourth surface faces the electrode assembly. The connector is disposed on the fourth surface, which faces the electrode assembly, such that the connector is located inside the first wall and the pressure relief mechanism. This reduces the external space occupied by the connector and helps to reduce the possibility of interference or collision between the connector and external components. When welding the pressure relief mechanism to the first wall, welding can be performed from the outside of the housing. Since the connector is located inside the first wall and the pressure relief mechanism, it can act as a barrier, reducing the risk of high-temperature substances generated during welding damaging the electrode assembly inside the housing. Furthermore, because the connector is disposed on the fourth surface, the protrusion of the pressure relief mechanism protrudes from the fourth surface, which faces the electrode assembly. This allows both the connector and the protrusion to be located inside the housing. The protrusion and the connector can share the internal space of the housing, making full use of the space reserved for the connector inside the housing. This reduces the impact of external components on the protrusion due to exposure to the outside of the housing, and allows the recess of the pressure relief mechanism to provide opening space when the weak point of the pressure relief mechanism is damaged, improving the pressure relief rate of the pressure relief mechanism.

[0034] In some embodiments, the connector is annular, and the buffer portion is arranged around the connector. The annular connector structure enables the annular welding of the pressure relief mechanism and the first wall, which is beneficial to improving the sealing performance and welding strength between the pressure relief mechanism and the first wall.

[0035] In some embodiments, the first wall further includes a wall body connected to the buffer section. The wall body is welded to the pressure relief mechanism. The thickness of the wall body is D, and the thickness of the buffer section is D1, where 0 ≤ (D-D1) / D ≤ 0.3. This ensures that the thickness of the wall body is not excessive while meeting the strength requirements of the first wall in the buffer section region, reducing the material used in the first wall and achieving better economic efficiency.

[0036] In some embodiments, 0 ≤ (D-D1) / D ≤ 0.1. Further reducing the thickness difference between the wall body and the buffer section ensures that if the strength of one of the buffer section and the wall body meets the requirements, the other can also meet the strength requirements.

[0037] In some embodiments, 0.1mm ≤ D ≤ 0.5mm. This not only meets the strength requirements of the first wall but also helps to reduce the impact on the volumetric energy density of the battery cell caused by excessive wall thickness.

[0038] In some embodiments, 0.15mm ≤ D ≤ 3.5mm. This further balances the strength requirements of the first wall and the volumetric energy density requirements of the individual cells.

[0039] In some embodiments, the pressure relief mechanism is made of steel. Making both the pressure relief mechanism and the first wall made of steel effectively reduces the welding difficulty between the pressure relief mechanism and the first wall, and improves the welding quality between them.

[0040] In some embodiments, the steel includes carbon steel or stainless steel.

[0041] In some embodiments, the housing includes a casing and an end cap, the casing having at least one opening, the end cap closing the opening, and the casing including a first wall. This allows the pressure relief mechanism to be welded to the casing, providing more installation space for the pressure relief mechanism and facilitating the installation of a larger pressure relief mechanism on the casing to improve the pressure relief capacity of the battery cell.

[0042] In some embodiments, the housing has openings at both opposite ends, and the housing includes two end caps that respectively close the two openings. This allows for a longer housing, enabling the battery cell to have a larger capacity.

[0043] In some embodiments, the housing is cuboid in shape and further includes a second wall adjacent to the first wall. The second wall has the largest outer surface area among the housing components. This design prevents the pressure relief mechanism from being located on the wall with the largest outer surface area, reducing the impact of electrode assembly expansion on the pressure relief mechanism. However, since the second wall has the largest outer surface area, it experiences the greatest impact when the electrode assembly expands. Deformation of the second wall due to electrode assembly expansion can cause some strain on the pressure relief mechanism through the first wall. However, because the first wall includes at least one buffer portion surrounding the pressure relief mechanism, the buffering effect of this portion mitigates the strain caused by the second wall's expansion through the first wall, thereby reducing the risk of premature failure of the pressure relief mechanism's weak points.

[0044] Secondly, embodiments of this application provide a battery device, including a single battery cell provided in any one of the embodiments of the first aspect.

[0045] Thirdly, embodiments of this application provide an electrical device, including a battery cell provided in any one of the embodiments of the first aspect or a battery device provided in any one of the embodiments of the second aspect. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0048] Figure 2 Exploded views of battery devices provided in some embodiments of this application;

[0049] Figure 3 Exploded views of a single battery cell provided in some embodiments of this application;

[0050] Figure 4 Cross-sectional views of a battery cell provided in some embodiments of this application;

[0051] Figure 5 for Figure 4 A magnified view of a section at point A in the middle;

[0052] Figure 6 for Figure 5 A magnified view of a section at point B in the middle;

[0053] Figure 7 Cross-sectional views of a battery cell provided for other embodiments of this application;

[0054] Figure 8 for Figure 7 A magnified view of a section at point C;

[0055] Figure 9 for Figure 8 A magnified view of a section at point D;

[0056] Figure 10 A partial cross-sectional view of a battery cell provided in some embodiments of this application;

[0057] Figure 11 for Figure 10 A magnified view of a section at point E in the middle;

[0058] Figure 12 This is a schematic diagram of the structure of the pressure relief mechanism provided in some embodiments of this application;

[0059] Figure 13 Partial views of the housing provided for some embodiments of this application;

[0060] Figure 14 for Figure 13 A magnified view of a section at point F in the middle;

[0061] Figure 15 Exploded views of the casing provided for some embodiments of this application.

[0062] Icons: 1-Outer shell; 11-Housing shell; 12-End cap; 13-First wall; 131-Pressure relief hole; 132-Buffer section; 133-Groove; 134-First surface; 135-Second surface; 136-Wall body; 14-Second wall; 15-Third wall; 16-Fourth wall; 2-Electrode assembly; 21-Positive electrode tab; 22-Negative electrode tab; 3-Pressure relief mechanism; 31-Weak section; 31a-Pressure relief groove; 32-Edge section; 321-Fourth surface; 322 - Fifth surface; 33- Recess; 34- Protrusion; 341- Side wall; 342- Bottom wall; 3421- Raised portion; 3422- Straight portion; 4- Electrode terminal; 5- Welding portion; 6- Connector; 61- Third surface; 10- Battery cell; 20- Housing; 201- First housing; 202- Second housing; 100- Battery assembly; 200- Controller; 300- Motor; 1000- Vehicle; Z- First direction; Y- Second direction; X- Third direction. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0064] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0065] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0066] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0067] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0068] In this application, "multiple" means two or more (including two).

[0069] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0070] Battery cells include, 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-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0071] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, reduces the risk of short circuits while allowing active ions to pass through.

[0072] In some embodiments, the positive electrode can be a positive electrode sheet, which may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0073] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0074] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be 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. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can 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.).

[0075] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials in battery cells may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 )), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds.

[0076] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0077] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0078] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. Foamed metal can be nickel foam, copper foam, aluminum foam, foam alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper 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.).

[0079] As an example, the negative electrode sheet may include a negative current collector and a negative active material disposed on at least one surface of the negative current collector.

[0080] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0081] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. 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. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials in battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0082] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0083] In some embodiments, the separator is a separator membrane. The separator membrane can be any known porous structure separator membrane with good chemical and mechanical stability.

[0084] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0085] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0086] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0087] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0088] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0089] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0090] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0091] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0092] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0093] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0094] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0095] In some implementations, the electrode assembly is a stacked structure.

[0096] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0097] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0098] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0099] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0100] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0101] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0102] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0103] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0104] As an example, a battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells.

[0105] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0106] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging multiple battery cells and fixing them together to form an independent module.

[0107] As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0108] In some embodiments, the battery device may be a battery pack, which may include a housing and one or more individual battery cell assemblies housed within the housing.

[0109] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0110] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0111] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0112] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0113] As an example, the housing can be part of the vehicle's chassis structure. For instance, the housing's roof can be at least part of the vehicle's floor, or the housing's frame can be at least part of the vehicle's crossbeams and longitudinal beams.

[0114] In some embodiments, the battery device refers to an energy storage device, which includes a housing with a door on at least one side. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0115] The development of battery technology must take into account multiple design factors, such as energy density, cycle life, discharge capacity, charge-discharge rate and other performance parameters. In addition, the reliability of individual battery cells also needs to be considered.

[0116] In battery technology, pressure relief mechanisms can be incorporated into individual battery cells to improve their reliability. These mechanisms have a significant impact on the reliability of the battery cell. For example, short circuits or overcharging can cause thermal runaway within the cell, leading to a sudden pressure surge. In such cases, pressure relief mechanisms release the internal pressure, reducing the risk of explosion or fire.

[0117] A single battery cell may include a casing and an electrode assembly, with the electrode assembly housed within the casing. A pressure relief mechanism may be welded to the casing. The pressure relief mechanism has a weak point, which allows it to release pressure inside the casing after the weak point is breached.

[0118] In typical battery cells, the outer casing is usually made of aluminum, which has low hardness and good plasticity. The welding stress generated during the welding of the pressure relief mechanism and the outer casing can be absorbed by the outer casing, which can greatly alleviate the impact of welding stress on the pressure relief mechanism.

[0119] However, to meet strength requirements, the aluminum casing needs to be thicker, affecting the volumetric energy density of the battery cells. Therefore, to improve the volumetric energy density of the battery cells, a steel casing can be used, and the casing wall thickness can be made thinner while meeting strength requirements. However, due to the high hardness of the steel casing, it is difficult for the casing to absorb the welding stress generated during the welding process between the pressure relief mechanism and the casing. The welding stress can easily affect the pressure relief mechanism, causing the weak points of the pressure relief mechanism to be damaged prematurely within the normal cycle, affecting the service life of the battery cells.

[0120] In view of this, embodiments of this application provide a battery cell, which includes a casing, an electrode assembly, and a pressure relief mechanism. The casing has a first wall, the first wall being made of steel, and the electrode assembly is housed within the casing. The pressure relief mechanism is disposed on and welded to the first wall, and the pressure relief mechanism has a weak portion configured to at least partially break when the internal pressure of the casing reaches a threshold, thereby releasing the internal pressure of the casing. The first wall includes at least one buffer portion surrounding the pressure relief mechanism.

[0121] In such a battery cell, the first wall includes a buffer portion surrounding the pressure relief mechanism. The buffer portion can absorb at least a portion of the welding stress generated by welding the pressure relief mechanism to the first wall, reducing the risk that the weak part of the pressure relief mechanism will be prematurely damaged within the normal cycle under the influence of welding stress, thereby improving the service life of the pressure relief mechanism and thus improving the service life of the battery cell.

[0122] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery cells and battery devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft.

[0123] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0124] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. A battery device 100 is disposed inside the vehicle 1000, and the battery device 100 may be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000.

[0125] The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, for the power needs of the vehicle 1000 during startup, navigation and driving.

[0126] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0127] Please refer to Figure 2 , Figure 2 This is an exploded view of a battery device 100 provided in some embodiments of this application. The battery device 100 may include a battery cell 10 and a housing 20 for housing the battery cell 10.

[0128] The housing 20 has an enclosed space inside for accommodating the battery cells 10. The housing 20 can have various structures. In some embodiments, the housing 20 may include a first housing 201 and a second housing 202, which are interlocked. The first housing 201 and the second housing 202 can have various shapes, such as cuboids or cylinders. The first housing 201 can be a hollow structure open on one side, and the second housing 202 can also be a hollow structure open on one side. The open side of the second housing 202 interlocks with the open side of the first housing 201, thus forming a housing 20 with an enclosed space. Alternatively, the first housing 201 can be a hollow structure open on one side, and the second housing 202 can be a plate-like structure, with the second housing 202 interlocked with the open side of the first housing 201, thus forming a housing 20 with a accommodating space.

[0129] In the battery device 100, there can be one or more battery cells 10. If there are multiple battery cells 10, they can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 10 are connected in both series and parallel. Alternatively, multiple battery cells 10 can be first connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed manner to form a whole, which is then housed within the housing 20. Another option is that all battery cells 10 can be directly connected in series, parallel, or in a mixed manner, and then the whole consisting of all battery cells 10 is housed within the housing 20.

[0130] Please refer to Figure 3 , Figure 3 This is an isometric view of a battery cell 10 provided in some embodiments of this application. The battery cell 10 may include a housing 1, an electrode assembly 2, and a pressure relief mechanism 3.

[0131] The housing 1 can be used to house components such as the electrode assembly 2 and the electrolyte. As an example, the housing 1 may include a housing 11 and an end cap 12.

[0132] The shell 11 can be a hollow structure with an opening at one end, or it can be a hollow structure with openings at both opposite ends. The shell 11 can be in various shapes, such as cylindrical or prismatic.

[0133] End cap 12 is a component that closes the opening of housing 11 to isolate the internal environment of battery cell 10 from the external environment. End cap 12 and housing 11 together define a receiving space for accommodating electrode assembly 2, electrolyte, and other components. The shape of end cap 12 can be adapted to the shape of housing 1. For example, if housing 11 is a cuboid structure, end cap 12 can be a rectangular plate structure adapted to housing 1; or if housing 11 is a cylindrical structure, end cap 12 can be a circular plate structure adapted to housing 11.

[0134] In an embodiment where the housing 11 has an opening at one end, one end cap 12 may be provided accordingly. In an embodiment where the housing 11 has openings at both opposite ends, two end caps 12 may be provided accordingly. The two end caps 12 respectively close the two openings of the housing 11, and the two end caps 12 and the housing 11 together define the receiving space.

[0135] The pressure relief mechanism 3 is a component for releasing the internal pressure of the battery cell 10. When the internal pressure of the battery cell 10 reaches a threshold, the pressure relief mechanism 3 discharges the internal medium of the battery cell 10 to achieve pressure relief. The discharge medium includes, but is not limited to: electrolyte, dissolved or broken positive and negative electrode plates, fragments of the separator, gases produced by the reaction, flames, etc. The pressure relief mechanism 3 can be welded to the outer casing 1. For example, the pressure relief mechanism 3 can be welded to the casing 11; or, for example, the pressure relief mechanism 3 can be welded to the end cap 12.

[0136] In some embodiments, the battery cell 10 may further include an electrode terminal 4, which is disposed on the housing 1. The electrode assembly 2 is provided with tabs, and the electrode terminal 4 is used for electrical connection with the tabs. The electrode terminal 4 may be disposed on the housing 11 of the housing 1 or on the end cap 12 of the housing 1. The electrode terminal 4 and the tab may be directly connected, for example, by direct welding. The electrode terminal 4 and the tab may also be indirectly connected, for example, by indirect connection through a current collector.

[0137] As an example, such as Figure 3 As shown, the housing 11 is a hollow structure with openings at both opposite ends. End caps 12 are provided at both opposite ends of the housing 11, and electrode terminals 4 are provided on each end cap 12. Electrode assemblies 2 have tabs at both opposite ends. The tab at one end of the electrode assembly 2 is the positive tab 21, and the tab at the other end is the negative tab 22. The electrode terminal 4 on one end cap 12 is electrically connected to the positive tab 21, and the electrode terminal 4 on the other end cap 12 is electrically connected to the negative tab 22. The housing 11 includes a first wall 13, a second wall 14, a third wall 15, and a fourth wall 16. The first wall 13 and the third wall 15 are arranged opposite each other along a first direction Z, and the second wall 14 and the fourth wall 16 are arranged opposite each other along a second direction Y. The housing 11 has openings at both ends along a third direction X, and the first direction Z, the second direction Y, and the third direction X are all perpendicular to each other. A pressure relief hole 131 is provided on the first wall 13, and the pressure relief mechanism 3 is welded to the first wall 13 and covers the pressure relief hole 131.

[0138] Please refer to Figures 4-6 , Figure 4 Cross-sectional views of a battery cell 10 provided in some embodiments of this application; Figure 5 for Figure 4 A magnified view of a section at point A in the middle; Figure 6 for Figure 5 A partial enlarged view at point B. This application provides a battery cell 10, including a housing 1, an electrode assembly 2, and a pressure relief mechanism 3. The housing 1 has a first wall 13, the first wall 13 being made of steel, and the electrode assembly 2 is housed within the housing 1. The pressure relief mechanism 3 is disposed on and welded to the first wall 13, and the pressure relief mechanism 3 has a weak portion 31, which is configured to be at least partially destroyed when the internal pressure of the housing 1 reaches a threshold, thereby releasing the internal pressure of the housing 1. The first wall 13 includes at least one buffer portion 132, which surrounds the pressure relief mechanism 3.

[0139] The first wall 13 can be formed by at least one end cap 12 in the outer casing 1, with the pressure relief mechanism 3 welded to the end cap 12; alternatively, the first wall 13 can be formed by at least one wall of the housing 11 of the outer casing 1, with the pressure relief mechanism 3 welded to the housing 11. The first wall 13 can be made of steel. In the embodiment where the end cap 12 serves as the first wall 13, the end cap 12 is made of steel, and the housing 11 can be made of steel or other materials, such as aluminum. In the embodiment where the wall of the housing 11 serves as the first wall 13, the entire housing 11 can be made of steel, and the end cap 12 can be made of steel or other materials, such as aluminum.

[0140] The pressure relief mechanism 3 can be an explosion-proof plate. The pressure relief mechanism 3 and the first wall 13 can be made of the same material, for example, both the pressure relief mechanism 3 and the first wall 13 can be made of steel; the pressure relief mechanism 3 and the first wall 13 can also be made of different materials, for example, the first wall 13 can be made of steel and the pressure relief mechanism 3 can be made of aluminum.

[0141] The first wall 13 may be provided with a pressure relief hole 131, and the pressure relief mechanism 3 may cover the pressure relief hole 131. At least a part of the pressure relief mechanism 3 may be located inside the pressure relief hole 131, and the pressure relief mechanism 3 may be welded to the first wall 13 by a seam weld; alternatively, the pressure relief mechanism 3 may be located on the side of the first wall 13 facing or away from the electrode assembly 2, and the overlapping area of ​​the pressure relief mechanism 3 and the first wall 13 may be welded by a through weld.

[0142] The weak point 31 can be a region with lower strength in the pressure relief mechanism 3, and it is more easily damaged than other regions of the pressure relief mechanism 3. It is understood that during the process of increasing internal pressure in the outer casing 1, the weak point 31 will be damaged first compared to other regions of the pressure relief mechanism 3. This damage can refer to cracking, breakage, or detachment. The thickness of the weak point 31 can be less than the thickness of other regions of the pressure relief mechanism 3, making it easier to damage. Alternatively, a pressure relief groove 31a can be provided on the pressure relief mechanism 3, reducing the thickness of a local area on the pressure relief mechanism 3 to form a weak point 31 with lower strength compared to other regions. Another approach is to change the grain size of a local area of ​​the pressure relief mechanism 3 to form a weak point 31 with lower strength compared to other regions; for example, by annealing a local area of ​​the pressure relief mechanism 3.

[0143] The weak point 31 can have various shapes, such as straight, arc, ring, U, H, N, V, Y, double Y, etc. As an example, in... Figures 4-6 In the illustrated embodiment, the pressure relief mechanism 3 is provided with a pressure relief groove 31a, and a weak part 31 is formed in the area where the pressure relief groove 31a is provided. The extension trajectory of the pressure relief groove 31a is the same as the extension trajectory of the weak part 31.

[0144] The buffer portion 132 is a portion of the first wall 13 that has a buffering function. The buffer portion 132 may have better deformability than other areas of the first wall 13 to achieve this buffering function. This can be achieved by thinning a local area of ​​the first wall 13 to form the buffer portion 132; by bending a local area of ​​the first wall 13 to form the buffer portion 132; or by changing the grain size of a local area of ​​the first wall 13, making that area softer, for example, by annealing a local area of ​​the first wall 13.

[0145] The buffer portion 132 is arranged around the pressure relief mechanism 3, such that the buffer portion 132 is located on the outer periphery of the pressure relief mechanism 3, that is, the buffer portion 132 surrounds the pressure relief mechanism 3. The buffer portion 132 can be arranged around the entire circumference of the pressure relief mechanism 3. The buffer portion 132 can be annular. It is understood that the buffer portion 132 can extend along a closed trajectory, which can be a circular trajectory, a polygonal trajectory, etc. The buffer portion 132 can also be arranged around the pressure relief mechanism 3 without being an entire circumference. The buffer portion 132 can extend along a curved, non-closed trajectory, which can be arc-shaped, U-shaped, etc. If the buffer portion 132 extends along a circular trajectory, then the buffer portion 132 is annular. There can be one or more buffer portions 132 in the first wall 13. As an example, in Figure 5 In the illustrated embodiment, there is one buffer section 132 in the first wall 13.

[0146] In this embodiment, the first wall 13 includes a buffer portion 132 surrounding the pressure relief mechanism 3. The buffer portion 132 can absorb at least a portion of the welding stress generated by welding the pressure relief mechanism 3 to the first wall 13, thereby reducing the risk that the weak part 31 of the pressure relief mechanism 3 will be damaged prematurely within the normal cycle under the influence of welding stress, improving the service life of the pressure relief mechanism 3, and thus improving the service life of the battery cell 10.

[0147] In some embodiments, please continue to refer to Figure 6 The first wall 13 is provided with a groove 133, and a buffer part 132 is formed in the area where the groove 133 is provided.

[0148] It is understandable that the groove 133 is arranged around the pressure relief mechanism 3. The groove 133 can be a groove extending along a closed trajectory or a groove extending along a curved, non-closed trajectory.

[0149] The groove 133 can be provided on the side of the first wall 13 facing the electrode assembly 2, or it can be provided on the side of the first wall 13 away from the electrode assembly 2.

[0150] The first wall 13 may be provided with a groove 133, such that the area of ​​the first wall 13 corresponding to the groove 133 is at least partially bent to form a buffer portion 132. For example... Figure 6 As shown, the first wall 13 may also be provided with a groove 133 to thin the area of ​​the first wall 13 corresponding to the groove 133, so as to form a buffer portion 132.

[0151] In this embodiment, the buffer portion 132 is formed by providing a groove 133 on the first wall 13, which simplifies the forming method of the buffer portion 132 and reduces the forming difficulty of the buffer portion 132.

[0152] In some embodiments, please refer to Figures 7-9 , Figure 7 A cross-sectional view of a battery cell 10 provided for other embodiments of this application; Figure 8 for Figure 7 A magnified view of a section at point C; Figure 9 for Figure 8 A partial enlarged view at point D. The electrode assembly 2 is disposed on one side of the first wall 13 along the first direction Z. Along the first direction Z, the first wall 13 has a first surface 134 and a second surface 135 disposed opposite to each other. At least one buffer portion 132 protrudes from the first surface 134, and the groove opening of the groove 133 corresponding to the buffer portion 132 protruding from the first surface 134 is formed on the second surface 135.

[0153] The first wall 13 and the electrode assembly 2 are disposed opposite each other along the first direction Z, which can be parallel to the thickness direction of the first wall 13.

[0154] Alternatively, the first surface 134 can face the electrode assembly 2, and the second surface 135 can face away from the electrode assembly 2. The first surface 134 can be the inner surface of the first wall 13, and the second surface 135 can be the outer surface of the first wall 13. In this case, at least one buffer portion 132 protrudes into the interior of the outer shell 1. Or, the second surface 135 can face the electrode assembly 2, and the first surface 134 can face away from the electrode assembly 2. The second surface 135 can be the inner surface of the first wall 13, and the first surface 134 can be the outer surface of the first wall 13. In this case, at least one buffer portion 132 protrudes outward from the outer shell 1. As an example, the first surface 134 and the second surface 135 can be planar, or they can be arranged parallel to each other.

[0155] In an embodiment where there is one buffer portion 132 in the first wall 13, the buffer portion 132 protrudes from the first surface 134, and the groove opening of the corresponding recess 133 is formed on the second surface 135. In an embodiment where there are multiple buffer portions 132 in the first wall 13, all buffer portions 132 may protrude from the first surface 134, and all groove openings of the recesses 133 may be formed on the second surface 135; alternatively, a portion of the buffer portions 132 may protrude from the first surface 134, with the groove opening of the corresponding recess 133 formed on the second surface 135, while another portion of the buffer portions 132 may not protrude from the first surface 134, and the groove opening of the corresponding recess 133 may be formed on the first surface 134. For buffer portions 132 that do not protrude from the first surface 134, the buffer portion 132 may or may not protrude from the second surface 135.

[0156] It should be noted that if the buffer portion 132 has a portion protruding from the first surface 134 along the direction from the second surface 135 to the first surface 134, it should be understood that the buffer portion 132 protrudes from the first surface 134.

[0157] For the groove 133 corresponding to the buffer portion 132 protruding from the first surface 134, the groove 133 may be recessed from the second surface 135 in a direction pointing from the second surface 135 to the first surface 134, so that the opening of the groove 133 is formed on the second surface 135. It can be understood that the groove opening is formed at the position where the groove wall of the groove 133 connects with the second surface 135.

[0158] In this embodiment, the buffer portion 132 protruding from the first surface 134 occupies more space in the first direction Z, which is beneficial to increase the thickness of the buffer portion 132 and reduce the setting of the groove 133, thereby reducing the influence of the excessive thickness of the buffer portion 132 on the strength of the first wall 13. The groove 133 is set on the second surface 135, and the buffer portion 132 corresponding to the groove 133 protrudes from the first surface 134. This structure allows the buffer portion 132 protruding from the first surface 134 to be in a bent state, so that the buffer portion 132 has better deformation ability. The buffer portion 132 has a better absorption effect on the welding stress generated by the welding of the pressure relief mechanism 3 and the first wall 13, further reducing the influence of welding stress on the weak part 31 of the pressure relief mechanism 3. On the other hand, the buffer portion 132 protruding from the first surface 134 enhances the ability of the first wall 13 to resist deformation.

[0159] In some embodiments, please continue to refer to Figure 9 Along the first direction Z, the deepest position of the groove 133 formed on the second surface 135 is farther away from the second surface 135 than the first surface 134.

[0160] For the groove 133 formed on the second surface 135, along the first direction Z, the distance between the deepest position of the groove 133 and the second surface 135 is the depth of the groove 133. If the depth of the groove 133 is greater than the distance between the first surface 134 and the second surface 135, then the deepest position of the groove 133 can be made to be farther away from the second surface 135 than the first surface 134.

[0161] In this embodiment, the deepest position of the groove 133 formed on the second surface 135 is further away from the second surface 135 along the first direction Z than the first surface 134. This structure increases the depth of the groove 133 formed on the second surface 135, which is beneficial to increase the curvature of the buffer portion 132 protruding from the first surface 134, and further enhances the absorption effect of the buffer portion 132 on the welding stress generated by the welding of the pressure relief mechanism 3 and the first wall 13.

[0162] In some embodiments, please refer to Figure 10 and Figure 11 , Figure 10 A partial cross-sectional view of a battery cell 10 provided in some embodiments of this application; Figure 11 for Figure 10 A partial enlarged view at point E. The first wall 13 includes a plurality of buffer portions 132, all of which are arranged around the pressure relief mechanism 3. At least one buffer portion 132 protrudes from the second surface 135, and a groove 133 corresponding to the buffer portion 132 protruding from the second surface 135 is formed on the first surface 134.

[0163] Multiple buffer sections 132 can be arranged at intervals or continuously along a direction perpendicular to the first direction Z. Figure 10 and Figure 11 In the illustrated embodiment, the buffer portion 132 is annular, and multiple buffer portions 132 are spaced apart along a direction perpendicular to the first direction Z, which is the radial direction of the extension trajectory of the buffer portion 132.

[0164] There are multiple buffer portions 132 and multiple grooves 133, with each buffer portion 132 corresponding to a groove 133. A portion of the buffer portions 132 protrudes from the first surface 134, and the openings of a portion of the grooves 133 (grooves corresponding to a portion of the buffer portions 132) are formed on the second surface 135; another portion of the buffer portions 132 protrudes from the second surface 135, and the openings of another portion of the grooves 133 (grooves corresponding to another portion of the buffer portions 132) are formed on the first surface 134.

[0165] In this embodiment, the first wall 13 includes a plurality of buffer portions 132, and the plurality of buffer portions 132 are arranged around the pressure relief mechanism 3. The plurality of buffer portions 132 can be used to absorb the welding stress generated by welding the pressure relief mechanism 3 and the first wall 13, thereby further reducing the impact of welding stress on the weak part 31 of the pressure relief mechanism 3. For the buffer portion 132 protruding from the second surface 135, the buffer portion 132 can occupy more space in the first direction Z, which is beneficial to increase the thickness of the buffer portion 132 and reduce the setting of the groove 133, thereby reducing the influence of the excessive thickness of the buffer portion 132 on the strength of the first wall 13. The groove 133 is set on the first surface 134, and the buffer portion 132 corresponding to the groove 133 protrudes from the second surface 135. This structure allows the buffer portion 132 protruding from the second surface 135 to be in a bent state, so that the buffer portion 132 has better deformation ability. The buffer portion 132 has a better absorption effect on the welding stress generated by the welding of the pressure relief mechanism 3 and the first wall 13, further reducing the influence of welding stress on the weak part 31 of the pressure relief mechanism 3. On the other hand, it enhances the ability of the buffer portion 132 protruding from the second surface 135 to resist deformation of the first wall 13. Furthermore, since the first wall 13 includes both a buffer portion 132 protruding from the first surface 134 and a buffer portion 132 protruding from the second surface 135, on the one hand, the direction of the forming force on the first wall 13 when forming the buffer portion 132 protruding from the first surface 134 is opposite to the direction of the forming force on the first wall 13 when forming the buffer portion 132 protruding from the second surface 135, which is beneficial to reduce the deformation of other areas of the first wall 13 except for the buffer portion 132; on the other hand, compared with a structure in which all buffer portions 132 protrude from the first surface 134, the deformation resistance of the first wall 13 can be increased.

[0166] In some embodiments, please continue to refer to Figure 11 Along the first direction Z, the deepest position of the groove 133 formed on the first surface 134 is farther away from the first surface 134 than the second surface 135.

[0167] For the groove 133 formed on the first surface 134, along the first direction Z, the distance between the deepest position of the groove 133 and the first surface 134 is the depth of the groove 133. If the depth of the groove 133 is greater than the distance between the first surface 134 and the second surface 135, then the deepest position of the groove 133 can be further away from the first surface 134 than the second surface 135.

[0168] In this embodiment, the deepest position of the groove 133 formed on the first surface 134 is farther away from the first surface 134 along the first direction Z than the second surface 135. This structure increases the depth of the groove 133 formed on the first surface 134, which is beneficial to increase the curvature of the buffer portion 132 protruding from the second surface 135, and further enhances the absorption effect of the buffer portion 132 on the welding stress generated by the welding of the pressure relief mechanism 3 and the first wall 13.

[0169] In some embodiments, please continue to refer to Figure 9 and Figure 11 The first surface 134 is positioned facing the electrode assembly 2.

[0170] It is understandable that the second surface 135 is disposed away from the electrode assembly 2, the first surface 134 is the inner surface of the first wall 13, and the second surface 135 is the outer surface of the first wall 13.

[0171] exist Figure 9 In the illustrated embodiment, there is one buffer portion 132 and one groove 133. The buffer portion 132 protrudes from the first surface 134 toward the electrode assembly 2, and the groove 133 has its opening formed on the second surface 135. Figure 11 In the illustrated embodiment, there are two buffer portions 132. One buffer portion 132 protrudes from the first surface 134 toward the direction close to the electrode assembly 2, and the groove opening of the corresponding groove 133 is formed on the second surface 135. The other buffer portion 132 protrudes from the second surface 135 toward the direction away from the electrode assembly 2, and the groove opening of the corresponding groove 133 is formed on the first surface 134.

[0172] In this embodiment, the first surface 134 faces the electrode assembly 2, causing the buffer portion 132 protruding from the first surface 134 to protrude into the interior of the outer casing 1. This reduces the space occupied by the buffer portion 132 in the outer casing 1, which helps to reduce the possibility of interference or collision between the buffer portion 132 and external components. Consequently, it reduces the risk that the weak part 31 of the pressure relief mechanism 3 will be prematurely damaged due to the impact force of the buffer portion 132 on the external component. The external components referred to here are components located outside the outer casing 1, such as other battery cells 10, the housing 20 in the battery device 100, etc.

[0173] In some embodiments, please continue to refer to Figure 9 and Figure 11 The first wall 13 is connected to the pressure relief mechanism 3 through the welding part 5. Along the width direction of the groove 133, the minimum distance between the groove 133 closest to the welding part 5 and the welding part 5 is L, 1mm≤L≤10mm.

[0174] The welded portion 5 can be a weld area formed by welding the pressure relief mechanism 3 and the first wall 13, or it can be at least a part of the portion formed by the fusion of the pressure relief mechanism 3 and the first wall 13 after welding. The welded portion 5 can be annular to achieve continuous welding of the pressure relief mechanism 3 and the first wall 13 along the circumference of the pressure relief mechanism 3; the welded portion 5 can also include multiple welding segments, which are spaced apart along the circumference of the pressure relief mechanism 3 to achieve intermittent welding of the pressure relief mechanism 3 and the first wall 13 along the circumference of the pressure relief mechanism 3.

[0175] The width direction of the groove 133 can be perpendicular to the first direction Z.

[0176] L can be any one of the following values: 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or any range between two of them.

[0177] In this embodiment, L ≥ 1 mm ensures a sufficient distance between the groove 133 closest to the welding part 5 and the welding part 5, reducing the impact of welding the pressure relief mechanism 3 to the first wall 13 on the buffer part 132 closest to the welding part 5, and reducing the welding difficulty between the pressure relief mechanism 3 and the first wall 13. L ≤ 10 mm ensures that the distance between the groove 133 closest to the welding part 5 and the welding part 5 is not too large, so as to free up more space on the first wall 13 for installing the pressure relief mechanism 3, which is beneficial for setting a larger pressure relief mechanism 3 on the first wall 13 to improve the pressure relief capacity of the battery cell 10.

[0178] In some embodiments, 3mm ≤ L ≤ 7mm.

[0179] L can be any one of the following values ​​or a range between any two: 3mm, 3.2mm, 3.5mm, 3.8mm, 4mm, 4.2mm, 4.5mm, 4.8mm, 5mm, 5.2mm, 5.5mm, 5.8mm, 6mm, 6.2mm, 6.5mm, 6.8mm, 7mm.

[0180] In this embodiment, L≥3mm further increases the distance between the groove 133 closest to the welding part 5 and the welding part 5, further reducing the welding difficulty between the pressure relief mechanism 3 and the first wall 13. L≤7mm is beneficial to further increase the area of ​​the pressure relief mechanism 3 on the first wall 13, so as to achieve large-area pressure relief by the pressure relief mechanism 3.

[0181] In some embodiments, the minimum width of the groove 133 is W, where 0.8mm ≤ W ≤ 8mm.

[0182] The groove 133 has an inner ring and an outer ring surrounding the pressure relief mechanism 3. The outer ring is located outside the inner ring, and the minimum distance between the outer ring and the inner ring is the minimum width of the groove 133.

[0183] W can take any one of the following values: 0.8mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, or any range between two values.

[0184] In this embodiment, W≥0.8mm reduces the difficulty of forming the groove 133. W≤8mm reduces the space occupied by the groove 133 on the first wall 13, so as to free up more space for the pressure relief mechanism 3 on the first wall 13.

[0185] In some embodiments, 1.5mm ≤ W ≤ 5mm.

[0186] W can be any one of the following values ​​or a range between any two: 1.5mm, 1.8mm, 2mm, 2.2mm, 2.5mm, 2.8mm, 3mm, 3.2mm, 3.5mm, 3.8mm, 4mm, 4.2mm, 4.5mm, 4.8mm, 5mm.

[0187] In this embodiment, W ≥ 1.5 mm, further reducing the molding difficulty of the groove 133. W ≤ 5 mm, further reducing the space occupied by the groove 133 on the first wall 13.

[0188] In some embodiments, please continue to refer to Figure 9 and Figure 11 The first wall 13 also includes a wall body 136 connected to the buffer part 132. The wall body 136 is welded to the pressure relief mechanism 3. The thickness of the wall body 136 is D, and the depth of the groove 133 is H, where H > D.

[0189] The wall body 136 can be the portion of the first wall 13 excluding the buffer portion 132. The thickness direction of the wall body 136 is the same as the thickness direction of the first wall 13, and the thickness direction of the wall body 136 can be parallel to the first direction Z. One of the inner and outer surfaces of the wall body 136 is the first surface 134, and the other is the second surface 135. The distance between the first surface 134 and the second surface 135 is the thickness of the wall body 136. In the direction perpendicular to the thickness of the wall body 136, the stiffness of the buffer portion 132 is less than that of the wall body 136, and the buffer portion 132 is more easily deformed than the wall body 136.

[0190] The buffer portion 132 can be arranged around the wall body 136, that is, the buffer portion 132 is located on the outer periphery of the entire wall body 136; for example Figure 14As shown, the wall body 136 may also include two parts. The buffer part 132 connects the two parts of the wall body 136. The buffer part 132 is arranged around a part of the wall body 136. This part of the wall body 136 is welded to the pressure relief mechanism 3. The other part of the wall body 136 is arranged around the buffer part 132. That is, the buffer part 132 is located on the outer periphery of a part of the wall body 136, and the other part of the wall body 136 is located on the outer periphery of the buffer part 132.

[0191] In this embodiment, the depth of the groove 133 is greater than or equal to the thickness of the wall body 136. Increasing the depth of the groove 133 is beneficial to increasing the degree of bending of the buffer part 132, and further enhancing the absorption effect of the buffer part 132 on the welding stress generated by the welding of the pressure relief mechanism 3 and the first wall 13.

[0192] In some embodiments, 0.6mm ≤ H ≤ 3mm.

[0193] H can be any one of the following values: 0.6mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3mm, or any value between two of them.

[0194] In this embodiment, H ≥ 0.6 mm, which reduces the difficulty of forming the groove 133 on the one hand, and makes the buffer part 132 have good deformation ability on the other hand, so as to enhance the absorption effect of the buffer part 132 on the welding stress generated by the welding of the pressure relief mechanism 3 and the first wall 13. H ≤ 3 mm ensures that the depth of the groove 133 is not too large, reducing the forming force on the first wall 13 when forming the groove 133, and reducing the risk of the first wall 13 being damaged during the forming process.

[0195] In some embodiments, 0.8mm ≤ H ≤ 1.5mm.

[0196] H can be any one of the following values: 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, or any range between two values.

[0197] In this embodiment, H ≥ 0.8 mm, which further reduces the molding difficulty of the groove 133 and further enhances the absorption effect of the buffer part 132 on the welding stress generated by the welding of the pressure relief mechanism 3 and the first wall 13. H ≤ 1.5 mm further reduces the risk of the first wall 13 being damaged during the molding of the groove 133.

[0198] In some embodiments, the groove 133 is stamped into the first wall 13.

[0199] For the groove 133 whose opening is formed on the first surface 134 of the first wall 13, during molding, the groove 133 can be punched out on the first wall 13 in the direction from the first surface 134 to the second surface 135, and a buffer portion 132 protruding from the second surface 135 is formed accordingly; for the groove 133 whose opening is formed on the second surface 135 of the first wall 13, during molding, the groove 133 can be punched out on the first wall 13 in the direction from the second surface 135 to the first surface 134, and a buffer portion 132 protruding from the first surface 134 is formed accordingly.

[0200] In this embodiment, the groove 133 is formed on the first wall 13 by stamping, which is a simple forming method.

[0201] In some embodiments, please continue to refer to Figure 10 and Figure 11 The first wall 13 includes multiple buffer sections 132, all of which are arranged around the pressure relief mechanism 3.

[0202] Along a direction perpendicular to the first direction Z, multiple buffer sections 132 can be arranged at intervals or continuously. The first wall 13 can have two, three, four or more buffer sections 132.

[0203] In this embodiment, the thickness of a local area of ​​the first wall 13 may be reduced to form a buffer portion 132; or a local area of ​​the first wall 13 may be bent to form a buffer portion 132; or the grain size of a local area of ​​the first wall 13 may be changed, making the area softer to form a buffer portion 132. The forming directions of the multiple buffer portions 132 may be the same or different.

[0204] In embodiments where the buffer portion 132 protrudes to one side of the first wall 13, multiple buffer portions 132 may protrude from the same side of the first wall 13; such as 10 and Figure 11 As shown, multiple buffer sections 132 may also protrude from opposite sides of the first wall 13.

[0205] In this embodiment, multiple buffer sections 132 can be used to absorb the welding stress generated by the welding of the pressure relief mechanism 3 and the first wall 13, further reducing the impact of welding stress on the weak part 31 of the pressure relief mechanism 3.

[0206] In some embodiments, please refer to Figures 8-11 The buffer portion 132 is bent in a plane perpendicular to the extending direction of the buffer portion 132.

[0207] The buffer section 132 extends along a closed trajectory, and the plane perpendicular to the extension direction of the buffer section 132 can be a cross section of the buffer section 132 perpendicular to the extension direction.

[0208] In a plane perpendicular to the extending direction of the buffer portion 132, the buffer portion 132 can be bent toward the electrode assembly 2 or away from the electrode assembly 2. The buffer portion 132 can be arc-shaped, zigzag-shaped, etc.

[0209] In this embodiment, the bent buffer portion 132 has better deformation capability, thereby enhancing the buffering capability of the buffer portion 132 and enhancing the absorption effect of the buffer portion 132 on the welding stress generated by the welding of the pressure relief mechanism 3 and the first wall 13.

[0210] In some embodiments, at least a portion of the buffer portion 132 is arc-shaped in a plane perpendicular to the extending direction of the buffer portion 132.

[0211] It is understood that at least a portion of the cross-section of the buffer portion 132 is arc-shaped. As an example, in... Figures 8-11 In the illustrated embodiment, the cross-section of the buffer portion 132 is generally arc-shaped.

[0212] In this embodiment, in the plane perpendicular to the extension direction of the buffer portion 132, the arc-shaped portion of the buffer portion 132 has a smoother transition. On the one hand, this reduces the possibility of stress concentration in the buffer portion 132, thereby reducing the risk of the buffer portion 132's strength decreasing due to stress concentration. On the other hand, it makes the buffer portion 132 have better deformation and recovery capabilities, further enhancing the buffering capacity of the buffer portion 132.

[0213] In some embodiments, please continue to refer to Figures 8-11 The electrode assembly 2 is disposed on one side of the first wall 13 along the first direction Z. The battery cell 10 also includes a connector 6. Along the first direction Z, a part of the first wall 13 and a part of the pressure relief mechanism 3 are located on the same side of the connector 6 and are connected by a welding part 5. The welding part 5 connects to the connector 6.

[0214] The connector 6 can be located inside or outside the housing 1. The first wall 13 has a first overlapping area that overlaps with a portion of the connector 6 along the first direction Z, and the pressure relief mechanism 3 has a second overlapping area that overlaps with another portion of the connector 6 along the first direction Z. The first overlapping area and the second overlapping area are connected by a welding part 5.

[0215] The connector 6 can be a metal part, made of materials such as steel, aluminum, or aluminum alloy. The first wall 13, the pressure relief mechanism 3, and the connector 6 are all connected to the welded part 5, which fixes the first wall 13, the pressure relief mechanism 3, and the connector 6 together. As an example, a portion of the welded part 5 can be embedded within the connector 6; the welded part 5 is formed by the fusion of the first wall 13, the pressure relief mechanism 3, and the connector 6 after welding.

[0216] In this embodiment, the connection 6 reduces the welding difficulty between the first wall 13 and the pressure relief mechanism 3, reduces the risk of the first wall 13 and / or the pressure relief mechanism 3 being welded through, and improves the welding quality between the first wall 13 and the pressure relief mechanism 3.

[0217] In some embodiments, the first wall 13 is provided with a groove 133, and a buffer portion 132 is correspondingly formed in the area where the groove 133 is provided. Along the first direction Z, the first wall 13 has a first surface 134 and a second surface 135 disposed opposite to each other, at least one buffer portion 132 protrudes from the first surface 134, and the groove 133 corresponding to the buffer portion 132 protruding from the first surface 134 is formed on the second surface 135, and the connector 6 is disposed on the first surface 134.

[0218] Alternatively, the first surface 134 can face the electrode assembly 2, and the second surface 135 can face away from the electrode assembly 2. The first surface 134 is the inner surface of the first wall 13, and the second surface 135 is the outer surface of the first wall 13. In this case, at least one buffer portion 132 protrudes into the interior of the outer casing 1, and the connector 6 is located inside the first wall 13 and within the outer casing 1. Alternatively, the second surface 135 can face the electrode assembly 2, and the first surface 134 can face away from the electrode assembly 2. The second surface 135 is the inner surface of the first wall 13, and the first surface 134 is the outer surface of the first wall 13. In this case, at least one buffer portion 132 protrudes outward from the outer casing 1, and the connector 6 is located outside the first wall 13 and outside the outer casing 1. Figures 8-11 In the illustrated embodiment, the first surface 134 is disposed facing the electrode assembly 2, and the connector 6 is located inside the housing 1.

[0219] In this embodiment, since the connector 6 is disposed on the first surface 134, the buffer portion 132 protruding from the first surface 134 and the connector 6 can share the space on the same side of the first wall 13 along the first direction Z, making the overall structure of the first wall 13 and the connector 6 more compact in the first direction Z.

[0220] In some embodiments, please continue to refer to Figure 9 and Figure 11 Along the first direction Z, the connector 6 has a third surface 61 that is opposite to the first surface 134, and the buffer portion 132 that protrudes from the first surface 134 does not extend beyond the third surface 61 in the direction from the first surface 134 to the third surface 61.

[0221] As an example, both the third surface 61 and the first surface 134 are planar, the third surface 61 is arranged parallel to the first surface 134, and the buffer portion 132 protruding from the first surface 134 along the first direction Z is closer to the second surface than the third surface 61.

[0222] In this embodiment, the buffer portion 132 protruding from the first surface 134 does not extend beyond the third surface 61. This structure allows the connector 6 to provide a certain degree of protection for the buffer portion 132. After other components come into contact with the third surface 61, they will be unable to continue moving towards the first surface 134, thereby reducing the risk of other components colliding with the buffer portion 132 and affecting the buffering capacity of the buffer portion 132.

[0223] In an embodiment where the first surface 134 faces the electrode assembly 2, other components may be internal components located inside the housing 1, such as the electrode assembly 2; in an embodiment where the second surface 135 faces the electrode assembly 2, other components may be external components located outside the housing 1, such as other battery cells 10, the housing 20 in the battery device 100, etc.

[0224] In some embodiments, in a projection plane perpendicular to the first direction Z, the orthographic projection of the connector 6 covers the orthographic projection of the welded portion 5.

[0225] As an example, both the connector 6 and the welded part 5 are annular. The connector 6 has an inner annular surface and an outer annular surface. The outer annular surface is located on the outer periphery of the inner annular surface. The projection of the connector 6 along the first direction Z is located between the inner annular surface and the outer annular surface, so that the orthographic projection of the connector 6 covers the orthographic projection of the welded part 5 in the projection plane perpendicular to the first direction Z.

[0226] In this embodiment, in the projection plane perpendicular to the first direction Z, the orthographic projection of the connector 6 covers the orthographic projection of the welded part 5. This structure can increase the area of ​​the connection interface between the welded part 5 and the connector 6, thereby improving the welding strength between the pressure relief mechanism 3 and the first wall 13.

[0227] In some embodiments, please refer to Figure 9 , Figure 11 and Figure 12 , Figure 12 This is a schematic diagram of the structure of a pressure relief mechanism 3 provided in some embodiments of this application. The pressure relief mechanism 3 includes an edge portion 32, a recess 33, and a protrusion 34. The edge portion 32 is connected to the first wall 13 via a welding portion 5. Along the first direction Z, the edge portion 32 has a fourth surface 321 and a fifth surface 322 disposed opposite to each other. The recess 33 is recessed from the fifth surface 322 in a direction pointing from the fifth surface 322 to the fourth surface 321. The protrusion 34 is disposed corresponding to the recess 33 and protrudes from the fourth surface 321. A weak portion 31 is formed in the protrusion 34. A connecting member 6 is disposed on the fourth surface 321.

[0228] Alternatively, the fourth surface 321 can face the electrode assembly 2, and the fifth surface 322 can face away from the electrode assembly 2. The fourth surface 321 is the inner surface of the edge portion 32, and the fifth surface 322 is the outer surface of the edge portion 32. The protrusion 34 protrudes into the interior of the outer shell 1. Or, the fifth surface 322 can face the electrode assembly 2, and the fourth surface 321 can face away from the electrode assembly 2. The fifth surface 322 is the inner surface of the edge portion 32, and the fourth surface 321 is the outer surface of the edge portion 32. The protrusion 34 protrudes into the exterior of the outer shell 1. If the fourth surface 321 faces the electrode assembly 2, the first surface 134 faces the electrode assembly 2; if the fifth surface 322 faces the electrode assembly 2, the second surface 135 faces the electrode assembly 2.

[0229] The recess 33 can be formed on the pressure relief mechanism 3 by stamping. During the forming process, a groove 133 can be stamped on the pressure relief mechanism 3 in the direction from the fifth surface 322 to the fourth surface 321, and a protrusion 34 protruding from the fourth surface 321 can be formed accordingly.

[0230] As an example, both the fourth surface 321 and the fifth surface 322 are planar and are arranged in parallel. A part of the connector 6 is disposed on the first surface 134, and another part of the connector 6 is disposed on the fourth surface 321. The first surface 134 is flush with the fourth surface 321, and the second surface 135 is flush with the fifth surface 322.

[0231] In this embodiment, the recess 33 is recessed from the fifth surface 322 of the edge portion 32 in the direction from the fifth surface 322 to the fourth surface 321. The protrusion 34, which forms the weak portion 31, is correspondingly disposed with the recess 33 and protrudes from the fourth surface 321. This structure of the pressure relief mechanism 3 has better resistance to deformation, reduces the impact of the battery cell 10's breathing effect on the weak portion 31, and thus reduces the risk of fatigue cracking of the weak portion 31. In addition, since the connector 6 is disposed on the fourth surface 321, the protrusion 34 and the connector 6 can share the space on the same side of the first wall 13 along the first direction Z, making the overall structure of the pressure relief mechanism 3 and the first wall 13 more compact in the first direction Z.

[0232] In some embodiments, please continue to refer to Figure 9 and Figure 11 Along the first direction Z, the connector 6 has a third surface 61 that is opposite to the fourth surface 321, and the protrusion 34 does not extend beyond the third surface 61 in the direction from the fourth surface 321 to the third surface 61.

[0233] As an example, both the fourth surface 321 and the third surface 61 are planar, the fourth surface 321 is arranged parallel to the third surface 61, and along the first direction Z, the protrusion 34 is closer to the fifth surface 322 than the third surface 61.

[0234] In this embodiment, the protrusion 34 does not extend beyond the third surface 61 in the direction from the fourth surface 321 to the third surface 61. This structure allows the connector 6 to provide a certain degree of protection for the protrusion 34. After other components come into contact with the third surface 61, they will be unable to continue moving towards the fourth surface 321, thereby reducing the risk of other components colliding with the protrusion 34 and causing the weak part 31 to be damaged prematurely.

[0235] In some embodiments, please continue to refer to Figure 12 The protrusion 34 includes a side wall 341 and a bottom wall 342. The side wall 341 connects the bottom wall 342 and the edge portion 32. The edge portion 32 surrounds the side wall 341. The side wall 341 surrounds the bottom wall 342. The side wall 341 protrudes from the fourth surface 321. The weak portion 31 is formed in the bottom wall 342.

[0236] The bottom wall 342 can be flat; it can also be non-flat, for example, the bottom wall 342 can be curved in a section parallel to the first direction Z. The thicknesses of the edge portion 32, the side wall 341, and the bottom wall 342 can be equal or unequal. The side wall 341 and the bottom wall 342 can together define the recess 33.

[0237] In this embodiment, the weak part 31 is formed on the bottom wall 342 of the protrusion 34, which can reduce the molding difficulty of the weak part 31 in the protrusion 34.

[0238] In some embodiments, at least a portion of the bottom wall 342 is raised in the direction from the fourth surface 321 to the fifth surface 322 to form a raised portion 3421.

[0239] The raised portion 3421 can be formed by the entire bottom wall 342 bulging along the direction from the fourth surface 321 to the fifth surface 322, or it can be formed by only a portion of the bottom wall 342 bulging along the direction from the fourth surface 321 to the fifth surface 322. In the embodiment where only a portion of the bottom wall 342 bulges along the direction from the fourth surface 321 to the fifth surface 322 to form the raised portion 3421, the weak portion 31 can be formed in the raised portion 3421 or in other areas of the bottom wall 342 other than the raised portion 3421.

[0240] exist Figure 12 In the illustrated embodiment, the bottom wall 342 further includes a straight portion 3422, which surrounds the raised portion 3421. The straight portion 3422 connects the raised portion 3421 and the side wall 341. The straight portion 3422 is provided with a pressure relief groove 31a to correspondingly form a weak portion 31. The pressure relief groove 31a is annular and surrounds the raised portion 3421.

[0241] In this embodiment, the raised portion 3421 protrudes along the direction from the fourth surface 321 to the fifth surface 322, effectively utilizing the space inside the side wall 341 and improving the deformation resistance of the bottom wall 342, reducing the impact of the breathing effect of the battery cell 10 on the weak portion 31, thereby reducing the risk of fatigue cracking of the weak portion 31.

[0242] In some embodiments, the protrusion 3421 does not extend beyond the fifth surface 322 in the direction from the fourth surface 321 to the fifth surface 322.

[0243] As an example, the cross-section of the raised portion 3421 parallel to the first direction Z is arc-shaped. Along the direction from the fourth surface 321 to the fifth surface 322, the highest point of the raised portion 3421 is lower than the fifth surface 322.

[0244] In this embodiment, the raised portion 3421 does not extend beyond the fifth surface 322 along the direction from the fourth surface 321 to the fifth surface 322. After other components come into contact with the fifth surface 322, they will be unable to continue moving towards the raised portion 3421, thereby reducing the risk of other components colliding with the raised portion 3421 and causing the weak portion 31 to be damaged prematurely.

[0245] In some embodiments, the fourth surface 321 faces the electrode assembly 2 ( Figure 9 and Figure 11 (Settings shown in the image).

[0246] It is understood that the recess 33 of the pressure relief mechanism 3 is disposed facing the outside of the housing 1, and the connector 6 is located inside the edge portion 32 and inside the housing 1.

[0247] As an example, the raised portion 3421 is closer to the electrode assembly 2 than the fifth surface 322.

[0248] In this embodiment, the fourth surface 321 faces the electrode assembly 2, and the connector 6 is disposed on the fourth surface 321, which also faces the electrode assembly 2. This allows the connector 6 to be located inside the first wall 13 and the pressure relief mechanism 3, reducing the external space occupied by the connector 6 and thus minimizing the possibility of interference or collision between the connector 6 and external components. When welding the pressure relief mechanism 3 to the first wall 13, welding can be performed from the outside of the outer casing 1. Since the connector 6 is located inside the first wall 13 and the pressure relief mechanism 3, it acts as a barrier, reducing the risk of high-temperature substances generated during welding damaging the electrode assembly 2 inside the outer casing 1. Furthermore, since the connector 6 is disposed on the fourth surface 321, the protrusion 34 of the pressure relief mechanism 3 protrudes from the fourth surface 321, and the fourth surface 321 faces the electrode assembly 2, so that both the connector 6 and the protrusion 34 are located inside the housing 1. The protrusion 34 and the connector 6 can share the internal space of the housing 1, making full use of the space left for the connector 6 inside the housing 1, reducing the impact of external components on the protrusion 34 due to exposure to the outside of the housing 1, and enabling the recess 33 of the pressure relief mechanism 3 to provide opening space for the pressure relief mechanism 3 when the weak part 31 is damaged, thereby improving the pressure relief rate of the pressure relief mechanism 3.

[0249] In some embodiments, please continue to refer to Figures 8-11 The connector 6 is annular, and the buffer part 132 is arranged around the connector 6.

[0250] The connector 6 can extend along a closed trajectory to form a ring structure. The buffer portion 132 can also be ring-shaped, and the buffer portion 132 is disposed around the connector 6, such that the buffer portion 132 is located on the outer periphery of the connector 6. In the projection plane perpendicular to the first direction Z, the orthographic projection of the buffer portion 132 can be referred to as the outer ring, and the orthographic projection of the connector 6 can be referred to as the inner ring, with the inner ring located inside the outer ring.

[0251] In this embodiment, the annular connector 6 can realize the annular welding between the pressure relief mechanism 3 and the first wall 13, which is beneficial to improve the sealing performance and welding strength of the pressure relief mechanism 3 and the first wall 13.

[0252] In some embodiments, please refer to Figure 13 and Figure 14 , Figure 13 Partial view of housing 1 provided for some embodiments of this application; Figure 14 for Figure 13 A partial enlarged view at point F. The first wall 13 also includes a wall body 136 connected to the buffer part 132. The wall body 136 is welded to the pressure relief mechanism 3. The thickness of the wall body 136 is D, and the thickness of the buffer part 132 is D1, where 0≤(D-D1) / D≤0.3.

[0253] The thickness of the wall body 136 can be greater than or equal to the thickness of the buffer part 132, i.e., D≥D1.

[0254] As an example, in Figure 14 In the illustrated embodiment, the thickness of the buffer portion 132 is the same as the wall thickness of the groove 133.

[0255] (D-D1) / D can take any one of the following point values ​​or any range between two values: 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, etc.

[0256] In this embodiment, the range of (D-D1) / D is set to 0-0.3, so that the thickness of the wall body 136 is not too large while the strength of the first wall 13 in the buffer part 132 region meets the requirements, thereby reducing the material used in the first wall 13 and achieving better economy.

[0257] In some embodiments, 0 ≤ (D - D1) / D ≤ 0.1.

[0258] (D-D1) / D can take any one of the following point values ​​or any range between two values: 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1.

[0259] In this embodiment, the range of (D-D1) / D is set to 0-0.1 to further reduce the thickness difference between the wall body 136 and the buffer portion 132, ensuring that if the strength of one of the buffer portion 132 and the wall body 136 meets the requirements, the other can also meet the strength requirements. Furthermore, in the embodiment where the first wall 13 is provided with a groove 133, setting the range of (D-D1) / D to 0-0.1 can effectively reduce the impact of the groove 133 on the strength of the buffer portion 132.

[0260] In some embodiments, 0.1mm ≤ D ≤ 0.5mm.

[0261] D can be any one of the following values: 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, or any value between two of them.

[0262] In this embodiment, 0.1mm≤D≤0.5mm not only meets the strength requirements of the first wall 13, but also helps to reduce the impact on the volumetric energy density of the battery cell 10 due to the excessive thickness of the wall body 136.

[0263] In some embodiments, 0.15mm ≤ D ≤ 3.5mm.

[0264] D can be any one of the following values ​​or a range between any two: 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm.

[0265] In this embodiment, 0.15mm≤D≤3.5mm further takes into account both the strength requirements of the first wall 13 and the volumetric energy density requirements of the battery cell 10.

[0266] In some embodiments, the pressure relief mechanism 3 is made of steel.

[0267] As an example, the pressure relief mechanism 3 is a steel explosion-proof plate.

[0268] In this embodiment, both the pressure relief mechanism 3 and the first wall 13 are made of steel, which can effectively reduce the welding difficulty of the pressure relief mechanism 3 and the first wall 13 and improve the welding quality of the pressure relief mechanism 3 and the first wall 13.

[0269] In some embodiments, the steel includes carbon steel or stainless steel.

[0270] Carbon steel can be Q195 carbon steel, SPCC carbon steel, etc.; stainless steel can be SUS430 stainless steel, SUS304 stainless steel, SUS316 stainless steel or modified stainless steel, etc.

[0271] In embodiments where both the pressure relief mechanism 3 and the first wall 13 are made of steel, both the pressure relief mechanism 3 and the first wall 13 can be made of carbon steel, both can be made of stainless steel, or one can be made of carbon steel and the other of stainless steel. If both the pressure relief mechanism 3 and the first wall 13 are made of carbon steel, one can be made of either Q195 carbon steel or SPCC carbon steel, and the other can be made of the same material. Similarly, if both the pressure relief mechanism 3 and the first wall 13 are made of stainless steel, one can be made of either SUS430 stainless steel, SUS304 stainless steel, or SUS316 stainless steel, and the other can be made of the same material.

[0272] In some embodiments, please refer to Figure 15 , Figure 15 The exploded view shows a housing 1 provided for some embodiments of this application. The housing 1 includes a shell 11 and an end cap 12. The shell 11 has at least one opening, and the end cap 12 closes the opening. The shell 11 includes a first wall 13.

[0273] The housing 11 may have an opening at only one end, and the end cap 12 may be one; or the housing 11 may have openings at both opposite ends, and the end cap 12 may be two.

[0274] The first wall 13 in the shell 11 can be one or more. As an example, the shell 1 is cuboid in shape, and one of the walls in the shell 11 is the first wall 13.

[0275] In this embodiment, the first wall 13 is a wall in the housing 11, so that the pressure relief mechanism 3 is welded to the housing 11. The housing 11 can provide a larger installation space for the pressure relief mechanism 3, which is beneficial to set a larger pressure relief mechanism 3 on the housing 11 to improve the pressure relief capacity of the battery cell 10.

[0276] In some embodiments, the housing 11 has openings at both opposite ends, and the housing 1 includes two end caps 12, which respectively close the two openings.

[0277] As an example, both end caps 12 are provided with through holes for mounting electrode terminals 4.

[0278] In this embodiment, the housing 11 has openings at both opposite ends, which makes it easier to make the housing 11 longer, so that the battery cell 10 has a larger capacity.

[0279] In some embodiments, the outer shell 1 is in the shape of a cuboid and the outer shell 1 further includes a second wall 14, which is disposed adjacent to the first wall 13 and is the wall with the largest outer surface area in the outer shell 1.

[0280] The outer shell 1 is rectangular and has six walls. The first wall 13 and the second wall 14 are two adjacent walls in the outer shell 1. Either the first wall 13 or the second wall 14 can be an end cap 12 and the other can be a wall in the shell 11; or both the first wall 13 and the second wall 14 can be walls in the shell 11.

[0281] In this embodiment, the electrode assembly 2 can be a wound structure or a stacked structure. The electrode assembly 2 can be flat, and its thickness direction can be parallel to the thickness direction of the second wall 14. The large surface of the electrode assembly 2 can face the second wall 14.

[0282] exist Figure 15In the illustrated embodiment, the housing 11 includes a first wall 13, a second wall 14, a third wall 15, and a fourth wall 16. The first wall 13 and the third wall 15 are disposed opposite each other along a first direction Z, and the second wall 14 and the fourth wall 16 are disposed opposite each other along a second direction Y. Openings are formed at both ends of the housing 11 along a third direction X. The first direction Z, the second direction Y, and the third direction X are mutually perpendicular. Along the circumference of the openings, adjacent walls of the first wall 13, the second wall 14, the third wall 15, and the fourth wall 16 are transitioned by an arc portion. The dimension of the housing 11 along the second direction Y is smaller than the dimension of the housing 11 along the first direction Z, and the dimension of the housing 11 along the first direction Z is smaller than the dimension of the housing 11 along the third direction X. The third direction X is parallel to the length direction of the battery cell 10, the second direction Y is parallel to the thickness direction of the battery cell 10, and the first direction Z is parallel to the width direction of the battery cell 10.

[0283] In this embodiment, the second wall 14, which is adjacent to the first wall 13, is the wall with the largest outer surface area in the outer casing 1. This means that the pressure relief mechanism 3 is not located on the wall with the largest outer surface area in the outer casing 1, reducing the impact of the expansion of the electrode assembly 2 on the pressure relief mechanism 3. Furthermore, since the second wall 14 has the largest outer surface area in the outer casing 1, the expansion of the electrode assembly 2 has the greatest impact on the second wall 14. After the second wall 14 deforms due to the expansion of the electrode assembly 2, it will exert a certain amount of tension on the pressure relief mechanism 3 through the first wall 13. However, since the first wall 13 includes at least one buffer portion 132, and the buffer portion 132 is arranged around the pressure relief mechanism 3, the buffering effect of the buffer portion 132 can alleviate the tension caused by the expansion of the electrode assembly 2 through the first wall 13 on the pressure relief mechanism 3, thereby reducing the risk of premature damage to the weak part 31 of the pressure relief mechanism 3.

[0284] This application provides a battery device 100, which includes a battery cell 10 provided in any of the above embodiments.

[0285] This application provides an electrical device, including a battery cell 10 or a battery device 100 provided in any of the above embodiments.

[0286] This application embodiment also provides a battery cell 10, which includes a housing 1, an electrode assembly 2, a pressure relief mechanism 3, and electrode terminals 4. The electrode assembly 2 is housed within the housing 1. The housing 1 is cuboid in shape and includes a shell 11 and two end caps 12. Both the shell 11 and the end caps 12 are made of steel. Along the first direction Z, both opposite ends of the shell 11 have openings, and each end cap 12 closes one opening. The shell 11 includes a first wall 13, a second wall 14, a third wall 15, and a fourth wall 16. The first wall 13 and the third wall 15 are arranged opposite each other along the first direction Z, and the second wall 14 and the fourth wall 16 are arranged opposite each other along the second direction Y. Both ends of the shell 11 along the third direction X form openings. The first direction Z, the second direction Y, and the third direction X are perpendicular to each other. The second wall 14 and the fourth wall 16 are the walls with the largest outer surface area in the housing 1. Electrode assembly 2 has tabs at both ends along the third direction X, namely a positive tab 21 and a negative tab 22. Both end caps 12 are provided with electrode terminals 4. The positive tab 21 is electrically connected to the electrode terminal 4 on one end cap 12, and the negative tab 22 is electrically connected to the electrode terminal 4 on the other end cap 12. The pressure relief mechanism 3 is made of steel and is disposed on and welded to the first wall 13. The pressure relief mechanism 3 is provided with a pressure relief groove 31a to form a corresponding weak part 31. The weak part 31 is configured to be at least partially destroyed when the internal pressure of the outer shell 1 reaches a threshold, so as to release the internal pressure of the outer shell 1.

[0287] The first wall 13 is stamped with a groove 133, and a buffer portion 132 is formed in the area where the groove 133 is provided. The buffer portion 132 is annular and surrounds the pressure relief mechanism 3. Along the first direction Z, the first wall 13 has a first surface 134 and a second surface 135 disposed opposite to each other. The first surface 134 faces the electrode assembly 2, the buffer portion 132 protrudes from the first surface 134, and the groove 133 is formed at the opening of the second surface 135. The deepest position of the groove 133 is further away from the second surface 135 than the first surface 134. The buffer portion 132 extends along a closed trajectory and is arc-shaped in a plane perpendicular to the extension direction of the buffer portion 132.

[0288] The battery cell 10 also includes a connector 6, which is annular, and a buffer portion 132 is arranged around the connector 6. Along the first direction Z, a portion of the first wall 13 and a portion of the pressure relief mechanism 3 are located on the same side of the connector 6. The portions of the first wall 13 and the pressure relief mechanism 3 located on the same side of the connector 6 are connected by a welding portion 5. The connector 6 is connected to the welding portion 5. In a projection plane perpendicular to the first direction Z, the orthographic projection of the connector 6 covers the orthographic projection of the welding portion 5. Along the width direction of the groove 133, the minimum distance between the groove 133 and the welding portion 5 is L, and the minimum width of the groove opening of the groove 133 is W, where 1mm≤L≤10mm and 0.8mm≤W≤8mm.

[0289] The pressure relief mechanism 3 includes an edge portion 32, a recess 33, and a protrusion 34. The edge portion 32 is connected to the first wall 13 via a welded portion 5. Along the first direction Z, the edge portion 32 has a fourth surface 321 and a fifth surface 322 disposed opposite to each other. The recess 33 is recessed from the fifth surface 322 in a direction pointing from the fifth surface 322 to the fourth surface 321. The protrusion 34 is disposed corresponding to the recess 33 and protrudes from the fourth surface 321. A weak portion 31 is formed on the protrusion 34. The fourth surface 321 is flush with the first surface 134, and the fifth surface 322 is flush with the second surface 135. A portion of the connector 6 is disposed on the fourth surface 321, and another portion of the connector 6 is disposed on the first surface 134. Along the first direction Z, the connector 6 has a third surface 61 that is opposite to the first surface 134. Along the direction from the first surface 134 to the third surface 61, the buffer portion 132 does not extend beyond the third surface 61. Along the direction from the fourth surface 321 to the third surface 61, the protrusion 34 does not extend beyond the third surface 61.

[0290] The protrusion 34 includes a sidewall 341 and a bottom wall 342. The sidewall 341 connects the bottom wall 342 and the edge portion 32. The edge portion 32 surrounds the sidewall 341, and the sidewall 341 surrounds the bottom wall 342. The sidewall 341 protrudes from the fourth surface 321, and a weak portion 31 is formed in the bottom wall 342. A portion of the bottom wall 342 protrudes along the direction from the fourth surface 321 to the fifth surface 322 to form a raised portion 3421. A pressure relief groove 31a is provided around the raised portion 3421 along the direction from the fourth surface 321 to the fifth surface 322. The raised portion 3421 does not extend beyond the fifth surface 322.

[0291] The first wall 13 also includes a wall body 136 connected to the buffer part 132. The wall body 136 is welded to the pressure relief mechanism 3. The thickness of the wall body 136 is D, the depth of the groove 133 is H, the thickness of the buffer part 132 is D1, H>D, 0≤(D-D1) / D≤0.3, 0.6mm≤H≤3mm, 0.1mm≤D≤0.5mm.

[0292] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0293] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit this application. For those skilled in the art, this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized by, The battery cell comprises: a shell having a first wall, a material of the first wall comprising steel; an electrode assembly accommodated in the shell; a pressure relief mechanism arranged on the first wall and weldedly connected with the first wall, the pressure relief mechanism having a weak portion configured to be at least partially destroyed when an internal pressure of the shell reaches a threshold value to release the internal pressure of the shell; wherein the first wall comprises at least one buffer portion arranged around the pressure relief mechanism.

2. The battery cell of claim 1, wherein, The first wall is provided with a groove, and the first wall corresponds to form the buffer portion in the region where the groove is arranged.

3. The battery cell of claim 2, wherein, The electrode assembly is arranged on one side of the first wall along a first direction, and the first wall has oppositely arranged first and second surfaces along the first direction. At least one of the buffer portions protrudes from the first surface, and a notch of the groove corresponding to the buffer portion protruding from the first surface is formed on the second surface.

4. The battery cell of claim 3, wherein, Along the first direction, the deepest position of the groove formed on the second surface is farther away from the second surface than the first surface.

5. The battery cell of claim 3, wherein the cathode comprises a lithium metal oxide. The first wall comprises a plurality of buffer portions, and the plurality of buffer portions are arranged around the pressure relief mechanism. At least one of the buffer portions protrudes from the second surface, and a notch of the groove corresponding to the buffer portion protruding from the second surface is formed on the first surface.

6. The battery cell of claim 5, wherein, Along the first direction, the deepest position of the groove formed on the first surface is farther away from the first surface than the second surface.

7. The battery cell of claim 3, wherein the cathode comprises a lithium metal oxide. The first surface faces the electrode assembly.

8. The battery cell of claim 2, wherein, The first wall and the pressure relief mechanism are connected by a welding portion. Along the width direction of the groove, the minimum distance between the groove closest to the welding portion and the welding portion is L, and 1mm≤L≤10mm; optionally, 3mm≤L≤7mm.

9. The battery cell of claim 2, wherein, The minimum width of the notch of the groove is W, and 0.8mm≤W≤8mm; optionally, 1.5mm≤W≤5mm.

10. The battery cell of claim 2, wherein, The first wall further comprises a wall body connected with the buffer portion, the wall body is weldedly connected with the pressure relief mechanism, the thickness of the wall body is D, the depth of the groove is H, and H>D.

11. The battery cell of claim 10, wherein the cathode comprises a lithium metal oxide. 0.6mm≤H≤3mm; optionally, 0.8mm≤H≤1.5mm.

12. The battery cell of claim 2, wherein, The groove is stamped and formed on the first wall.

13. The battery cell of any one of claims 1-12, wherein, The first wall comprises a plurality of buffer portions, and the plurality of buffer portions are arranged around the pressure relief mechanism.

14. The battery cell of any one of claims 1-12, wherein, In a plane perpendicular to the extension direction of the buffer portion, the buffer portion is curvedly arranged.

15. The battery cell as described in claim 14, characterized in that, In a plane perpendicular to the extension direction of the buffer portion, at least part of the buffer portion is arc-shaped.

16. The battery cell of any one of claims 1-12, wherein, The electrode assembly is arranged on one side of the first wall along a first direction, and the battery cell further comprises a connecting piece. Along the first direction, a part of the first wall and a part of the pressure relief mechanism are located on the same side of the connecting piece and are connected by a welding portion, and the welding portion connects the connecting piece.

17. The battery cell as described in claim 16, characterized in that, The first wall is provided with a groove, and the first wall corresponds to form the buffer portion in the region where the groove is arranged. In the first direction, the first wall has oppositely arranged first and second surfaces, at least one of the buffer portions protrudes from the first surface, and a groove corresponding to the buffer portion protruding from the first surface is formed in the second surface, and the connecting piece is arranged on the first surface.

18. The battery cell of claim 17, wherein, In the first direction, the connecting piece has a third surface facing away from the first surface, and in a direction along the first surface and pointing toward the third surface, the buffer portion protruding from the first surface does not exceed the third surface.

19. The battery cell as described in claim 16, characterized in that, In a projection plane perpendicular to the first direction, the connecting piece covers the weld in plan view.

20. The battery cell as described in claim 16, characterized in that, The pressure relief mechanism comprises: an edge portion connected to the first wall by the weld, in the first direction, the edge portion has oppositely arranged fourth and fifth surfaces; a recess recessed from the fifth surface in a direction along the fifth surface and pointing toward the fourth surface; a protrusion corresponding to the recess and protruding from the fourth surface, and the weak portion is formed in the protrusion; wherein the connecting piece is arranged on the fourth surface.

21. The battery cell of claim 20, wherein, In the first direction, the connecting piece has a third surface facing away from the fourth surface, and in a direction along the fourth surface and pointing toward the third surface, the protrusion does not exceed the third surface.

22. The battery cell as described in claim 20, characterized in that, The protrusion comprises a side wall and a bottom wall, the side wall connects the bottom wall and the edge portion, the edge portion is surrounded by the side wall, the side wall is surrounded by the bottom wall, the side wall protrudes from the fourth surface, and the weak portion is formed in the bottom wall.

23. The battery cell as described in claim 22, characterized in that, At least part of the bottom wall is raised to form a raised portion in a direction along the fourth surface and pointing toward the fifth surface.

24. The battery cell as described in claim 23, characterized in that, In the direction along the fourth surface and pointing toward the fifth surface, the raised portion does not exceed the fifth surface.

25. The battery cell of any one of claims 20-24, wherein, The fourth surface faces the electrode assembly.

26. The battery cell as described in claim 16, characterized in that, The connecting piece is annular, and the buffer portion is arranged around the connecting piece.

27. The battery cell of any one of claims 1-12, wherein, The first wall further comprises a wall body connected to the buffer portion, the wall body is welded to the pressure relief mechanism, the thickness of the wall body is D, the thickness of the buffer portion is D1, and 0≤(D-D1) / D≤0.3; optionally, 0≤(D-D1) / D≤0.

1.

28. The battery cell as described in claim 27, characterized in that, 0.1mm≤D≤0.5mm; optionally, 0.15mm≤D≤3.5mm.

29. The battery cell of any one of claims 1-12, wherein, The material of the pressure relief mechanism comprises steel.

30. The battery cell of any one of claims 1-12, wherein, The steel comprises carbon steel or stainless steel.

31. The battery cell of any one of claims 1-12, wherein, The shell comprises: a shell body having at least one opening; an end cover closing the opening; wherein the shell body comprises the first wall.

32. The battery cell as described in claim 31, characterized in that, Both ends of the shell body have the opening, and the shell comprises two end covers, and the two end covers respectively close the two openings.

33. The battery cell of any one of claims 1-12, wherein, The shell is cuboid-shaped, and the shell further comprises a second wall arranged adjacent to the first wall, and the second wall is the wall with the largest outer surface area in the shell.

34. A battery device, characterized by The battery cell as claimed in any one of claims 1-33.

35. An electrical device, comprising: The battery device as claimed in claim 34.

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