Battery cell, battery apparatus, and electric device

Abstract

A battery cell (20), a battery apparatus (10), and an electric device. The battery cell (20) comprises: a housing (211) having a first wall (201), the first wall (201) being provided with a pressure relief hole (202); a pressure relief mechanism (213) covering the pressure relief hole (202), the base material of the pressure relief mechanism (213) being iron, wherein the pressure relief mechanism (213) comprises a fragile portion (2132), a body portion (2131) and a connecting portion (2133); the fragile portion (2132) is configured to rupture to release pressure inside the housing (211) when the pressure reaches a threshold, the body portion (2131) is located in the area enclosed by the fragile portion (2132), and the connecting portion (2133) is located outside the fragile portion (2132) and is used for connection to the first wall (201); and the body portion (2131) is a raised structure protruding in the direction close to the electrode assembly (22) or away from the electrode assembly (22). The battery cell (20), battery apparatus (10) and electric device provided herein can extend the service life of the battery cell.

Description

Battery cell, battery device and electric equipment TECHNICAL FIELD

[0001] The present application relates to the field of battery, more particularly, to a battery cell, a battery device and an electric equipment. BACKGROUND

[0002] Energy saving and emission reduction is the key to the sustainable development of the automobile industry. In this case, electric vehicles have become an important part of the sustainable development of the automobile industry due to their energy saving and environmental protection advantages. For electric vehicles, battery technology is an important factor for its development. In the development of battery technology, in addition to improving the performance of the battery device, how to improve the service life of the battery device while ensuring the use safety of the battery device is also an issue that cannot be ignored.

[0003] SUMMARY

[0004] The embodiments of the present application provide a battery cell, a battery device and an electric equipment, which can improve the service life of the battery cell.

[0005] In a first aspect, a battery cell is provided, comprising: a shell having a first wall, the first wall being provided with a pressure relief hole; an electrode assembly accommodated in the shell; a pressure relief mechanism covering the pressure relief hole, a base material of the pressure relief mechanism being iron; wherein the pressure relief mechanism comprises a weak part, a body part and a connecting part, the weak part being configured to be damaged to release pressure when the pressure inside the shell reaches a threshold value, the body part being located in an area surrounded by the weak part, and the connecting part being located outside the weak part and being used to connect the first wall; the body part is a protruding structure protruding towards the direction close to the electrode assembly or the direction away from the electrode assembly.

[0006] Therefore, in the use process of the battery cell of the embodiments of the present application, the electrode assembly repeatedly expands and shrinks, and the weak part of the pressure relief mechanism is repeatedly pulled and shrunk, which is prone to fatigue; the body part protrudes relative to the weak part, whether the body part protrudes towards the inside or outside of the battery cell, it can play a buffering role, can bear part of the stress, reduce the deformation of the weak part, and reduce the fatigue of the weak part. In addition, along the thickness direction of the pressure relief mechanism, the pressure inside the battery cell repeatedly increases and decreases, and the middle area of the flat pressure relief mechanism will repeatedly protrude and recess towards the inside and outside of the battery cell, which will also cause the weak part of the pressure relief mechanism to be repeatedly bent and prone to fatigue; in the case that the body part protrudes relative to the weak part, whether the body part protrudes towards the inside or outside of the battery cell, it can maintain the shape of the body part, reduce the bending angle of the weak part, and further reduce the fatigue of the weak part, improve the service life of the pressure relief mechanism, and further improve the service life of the battery cell.

[0007] In some embodiments, the material of the pressure relief mechanism comprises stainless steel and / or carbon steel. The pressure relief mechanism made of stainless steel has high structural strength and can prevent corrosion, thereby effectively prolonging the service life of the pressure relief mechanism. The pressure relief mechanism made of carbon steel has greater structural strength, which is conducive to improving the structural stability and reliability of the pressure relief mechanism.

[0008] In some embodiments, the electrode assembly comprises at least two layers of electrode sheets; the at least two layers of electrode sheets are stacked in a first direction; or the at least two layers of electrode sheets are wound, and each of the at least two layers of electrode sheets comprises a flat section at the middle of the electrode assembly and a curved section at both ends of the electrode assembly, and the stacking direction of the at least two layers of electrode sheets at the flat section is the first direction; and the cross section of the body portion in at least one plane perpendicular to the first direction is arc-shaped. The cross section of the body portion in at least one plane perpendicular to the first direction is arc-shaped, which can effectively absorb the deformation of the electrode assembly, improve the deformation capacity of the pressure relief mechanism, and further improve the service life of the pressure relief mechanism.

[0009] In some embodiments, the protrusion height of the body portion relative to the weak portion is in the range of [0.5mm, 4mm].

[0010] In some embodiments, the protrusion height of the body portion relative to the weak portion is in the range of [0.8mm, 2mm].

[0011] The protrusion height of the body portion relative to the weak portion is greater than or equal to 0.5mm, or further, the protrusion height of the body portion relative to the weak portion is greater than or equal to 0.8mm, which can enable the body portion to effectively absorb the deformation and improve the structural stability of the body portion. The protrusion height of the body portion relative to the weak portion is less than or equal to 4mm, or further, the protrusion height of the body portion relative to the weak portion is less than or equal to 2mm, which can limit the space occupied by the body portion, thereby limiting the space occupied by the pressure relief mechanism, improving the space utilization of the battery monomer, and further improving the energy density of the battery monomer.

[0012] In some embodiments, the connecting portion comprises a fixed region for connecting with the first wall and a transition region for connecting the fixed region with the weak portion, the fixed region is arranged parallel to the first wall, the transition region is flush with the fixed region, or the transition region protrudes towards the electrode assembly relative to the fixed region; the body portion protrudes towards the electrode assembly relative to the fixed region. When the battery cell is in normal operation, the transition region and the body portion can inhibit cracking of the weak portion, reduce the risk of creep failure of the pressure relief mechanism when the battery cell is in normal operation, and effectively prolong the service life of the pressure relief mechanism. On the other hand, the outwardly protruding body portion can support the transition region and the weak portion, and can effectively extrude the weak portion. When the internal pressure or temperature of the battery cell continues to rise until greater than or equal to a predetermined value, the battery cell may

[0013] In some embodiments, the connecting portion comprises a fixed region for connecting with the first wall and a transition region for connecting the fixed region with the weak portion, the fixed region is arranged parallel to the first wall, the transition region and the body portion both protrude away from the electrode assembly relative to the weak portion. When the battery cell is in normal operation, the transition region and the body portion can inhibit cracking of the weak portion, reduce the risk of creep failure of the pressure relief mechanism when the battery cell is in normal operation, and effectively prolong the service life of the pressure relief mechanism. On the other hand, the outwardly protruding body portion can support the transition region and the weak portion, and can effectively extrude the weak portion. When the internal pressure or temperature of the battery cell continues to rise until greater than or equal to a predetermined value, the battery cell may

[0014] In some embodiments, the transition region protrudes towards the electrode assembly relative to the fixed region, and the inclination angle of the transition region relative to the fixed region is in the range of [40°, 75°], so as to control the bending degree between the transition region and the fixed region not to be too large or too small, reduce the stress concentration in the region between the transition region and the fixed region, and improve the structural strength.

[0015] In some embodiments, the thickness of the shell is in the range of [0.075mm, 0.4mm]; and / or, the thickness of the body portion is in the range of [0.075mm, 0.4mm].

[0016] In some embodiments, the thickness of the shell is in the range of [0.075mm, 0.25mm]; and / or, the thickness of the body portion is in the range of [0.075mm, 0.25mm].

[0017] In one aspect, the thickness of the shell is greater than or equal to 0.075 mm, which is easy to process and can improve the structural strength of the shell, thereby improving the structural stability of the battery cell. On the other hand, the thickness of the shell is less than or equal to 0.4 mm, or further, the thickness of the shell is less than or equal to 0.25 mm, which can reduce the volume of the battery cell, and can effectively reduce the weight of the battery cell and improve the energy density of the battery cell. For example, the material of the shell can include steel to facilitate the design requirements of the thickness of the shell.

[0018] In addition, the thickness of the body portion is greater than or equal to 0.075 mm, which is easy to process and can improve the structural strength of the pressure relief mechanism as a whole, thereby improving the structural stability of the battery cell. The thickness of the body portion is less than or equal to 0.4 mm, or further, the thickness of the pressure relief mechanism is less than or equal to 0.25 mm, which can reduce the volume occupied by the pressure relief mechanism, and can effectively reduce the weight of the battery cell and improve the energy density of the battery cell.

[0019] In some embodiments, the base material of the shell is iron to improve the structural strength of the shell.

[0020] In some embodiments, the battery cell further comprises a support structure fixed to the side of the first wall facing the electrode assembly, the pressure relief mechanism is located on the side of the support structure away from the electrode assembly, and the pressure relief mechanism is welded to at least one of the support structure and the first wall. In one aspect, the support structure can play a positioning role in the fixed connection of the pressure relief mechanism and the first wall, and the support structure can also be used to realize the connection and fixation between the pressure relief mechanism and the first wall, which can effectively improve the processing efficiency of the battery cell. On the other hand, the support structure can also be used to support the pressure relief mechanism and the first wall, increase the structural strength and stability between the first wall and the pressure relief mechanism, and especially during the use of the battery cell, the battery cell will swell, the support structure can be used to resist deformation, reduce the cracking between the pressure relief mechanism and the first wall caused by the swelling of the battery cell, and improve the stability of the battery cell.

[0021] In some embodiments, the support structure and the first wall are fixed by welding or by adhesion, which is simple to operate, structurally stable, and easy to implement.

[0022] In some embodiments, the materials of the pressure relief mechanism, the support structure and the first wall all include iron, copper or titanium. On one hand, the pressure relief mechanism, the support structure and the first wall have the same material, facilitating the mutual fixation among the three by welding; on the other hand, the structural strength of the pressure relief mechanism, the support structure and the first wall can be improved by the materials of iron, copper or titanium, while the thickness of the pressure relief mechanism, the support structure and the first wall is reduced, thereby improving the energy density of the battery cell. Moreover, since the strength of these materials is large, the first wall is difficult to be processed into a stepped structure by stamping or the like, and thus the pressure relief mechanism is difficult to be installed on the stepped structure of the first wall. In the process of fixing the pressure relief mechanism and the first wall by seam welding or penetration welding, the welding area of the pressure relief mechanism and the first wall needs to be supported by the support structure, which can also reduce the phenomenon of laser leakage caused by the gap between the pressure relief mechanism and the first wall in the welding process, and improve the welding strength.

[0023] In some embodiments, the surface of the pressure relief mechanism facing the electrode assembly is not more than the surface of the support structure facing the electrode assembly. No matter the body part of the pressure relief mechanism protrudes towards the inside or outside of the battery cell, the surface of the pressure relief mechanism facing the electrode assembly is not more than the surface of the support structure facing the electrode assembly, so as to protect the pressure relief mechanism.

[0024] In some embodiments, the thickness of the support structure is in the range of [0.4mm, 1.5mm].

[0025] In some embodiments, the thickness of the support structure is in the range of [0.4mm, 0.8mm].

[0026] The thickness of the support structure is greater than or equal to 0.4mm, which can increase the structural strength and stability of the support structure; and the thickness of the support structure is less than or equal to 1.5mm, and further, the thickness of the support structure is less than or equal to 0.8mm, which can reduce the overall volume of the support structure, thereby reducing the internal space of the battery cell occupied by the support structure and improving the energy density of the battery cell.

[0027] In some embodiments, the battery cell further comprises a protection member fixed to the side of the first wall facing the electrode assembly, the surfaces of the support structure and the pressure relief mechanism facing the electrode assembly protrude from the surface of the first wall facing the electrode assembly, and the surface of the protection member facing the electrode assembly protrudes from the surfaces of the support structure and the pressure relief mechanism facing the electrode assembly. This can reduce the influence of the components inside the battery cell on the support structure and the pressure relief mechanism, and improve the reliability of the pressure relief mechanism and the battery cell.

[0028] In some embodiments, the protection member comprises a first part and a second part arranged in a spaced manner, and the pressure relief mechanism and the support structure are located between the first part and the second part. Arranging the protection member in a split manner can reduce the processing difficulty of the protection member. In particular, when the area of the first wall is limited, there may be a part of the area around the pressure relief mechanism that is too small in size. Therefore, by not arranging the protection member in this part of the area, the processing difficulty of the protection member can be reduced. Moreover, the pressure relief mechanism is located between the first part and the second part, and the pressure relief mechanism can still be effectively protected.

[0029] In some embodiments, the protection member is provided with a relief opening for avoiding the pressure relief mechanism and the support structure. The processing is simple, and the pressure relief mechanism can be avoided through the relief opening, thereby reducing the obstruction to the pressure relief mechanism, so that the pressure relief mechanism can be actuated in time when the battery cell is in thermal runaway.

[0030] In some embodiments, the protection member is provided with a groove with an opening facing the pressure relief mechanism, the groove is used to accommodate the pressure relief mechanism and the support structure, the bottom of the groove is provided with a thinned area corresponding to the pressure relief mechanism, and the thickness of the thinned area is smaller than the thickness of other areas of the bottom of the groove. On the one hand, the internal space of the groove can be used to avoid the pressure relief mechanism and the support structure, and the thinned area provided on the bottom wall of the groove can be used to be damaged in time when the battery cell is in thermal runaway, so as to reduce the influence of the bottom wall of the groove on the pressure relief mechanism, so that the pressure relief mechanism can be damaged in time and the pressure inside the battery cell can be released in time. In addition, the surface of the protection member facing the inside of the battery cell is a continuous plane without discontinuous areas, so that the electrode assembly can enter the shell more continuously and smoothly, thereby improving the installation efficiency.

[0031] In some embodiments, the pressure relief mechanism, the inner wall of the pressure relief hole, and the support structure are connected by the same weld, and the same weld is located on the side of the support structure away from the electrode assembly. In this way, the support structure, the first wall, and the pressure relief mechanism can be welded and fixed at the same time, the welding efficiency is high, and the processing efficiency of the battery cell can be improved. Moreover, the connecting part is directly welded to the inner wall of the pressure relief hole, so as to reduce the gap between the connecting part of the pressure relief mechanism and the inner wall of the pressure relief hole as much as possible, thereby improving the sealing performance and reliability of the battery cell.

[0032] In some embodiments, the pressure relief mechanism and the support structure are connected by the same weld, the first wall and the support structure are connected by the same weld, and the weld between the pressure relief mechanism and the support structure is different from the weld between the first wall and the support structure. In this way, the relative fixation between the pressure relief mechanism and the first wall can be realized through the support structure, and the fixation mode is more flexible.

[0033] In some embodiments, the pressure relief mechanism, the support structure and the first wall are stacked along the thickness direction of the first wall, and are connected by the same welding seam, which is convenient for processing and can improve the structural strength and reliability of the battery cell.

[0034] In some embodiments, at least one welding seam is provided between the pressure relief mechanism, the support structure and the first wall, and the orthographic projection of the at least one welding seam towards the outer surface of the support structure is located in the middle region of the outer surface of the support structure along the thickness direction of the first wall, the outer surface of the support structure being the surface of the support structure away from the electrode assembly. The outer surface of the support structure can cover the at least one welding seam between the pressure relief mechanism, the support structure and the first wall, and the at least one welding seam does not exceed the outer surface of the support structure, which increases the stability of the support structure and improves the stability of the battery cell.

[0035] In some embodiments, the orthographic projection of the at least one welding seam towards the outer surface of the support structure is symmetrically distributed relative to the center line of the outer surface of the support structure along the thickness direction of the first wall, so that the at least one welding seam is uniformly distributed on the surface of the support structure, reducing the risk of the welding seam deviating from the outer surface of the support structure, and improving the structural stability and reliability.

[0036] In some embodiments, the side of the welding seam towards the electrode assembly does not exceed the surface of the support structure towards the electrode assembly, i.e. the support structure is not welded through during welding, so as to prevent damage to other components inside the battery cell and improve the welding efficiency and effect, thereby improving the processing yield and structural stability of the battery cell.

[0037] In some embodiments, the battery cell further comprises a protective sheet located on the side of the pressure relief mechanism away from the electrode assembly to protect the pressure relief mechanism, reduce damage to the pressure relief mechanism from external components of the battery cell, and improve the service life of the pressure relief mechanism.

[0038] In some embodiments, the side of the connecting portion away from the electrode assembly is provided with a stepped structure, the protective sheet is fixed to the bottom wall of the stepped structure, and the side of the body portion away from the electrode assembly does not exceed the bottom wall of the stepped structure. By providing the stepped structure to accommodate at least part of the protective sheet, the height of the surface of the protective sheet towards the outside of the battery cell can be reduced, for example, by setting the depth of the stepped structure so that the surface of the protective sheet towards the outside of the battery cell does not exceed the surface of the first wall towards the outside of the battery cell, so that the outer surface of the battery cell is relatively smooth, reducing local protrusions, facilitating the arrangement of multiple battery cells in a battery device, reducing the mutual influence of multiple battery cells, and improving the space utilization of the battery device, thereby improving the energy density of the battery device.

[0039] In some embodiments, the protective sheet is fixed to a side of the first wall away from the electrode assembly, and the protective sheet covers a weld joint between the pressure relief mechanism and the first wall. By covering the pressure relief mechanism with a protective sheet, the pressure relief mechanism can be protected. Further, the protective sheet can also be used to cover the weld joint between the pressure relief mechanism and the first wall, so as to protect the weld joint and improve the stability and reliability of the weld joint between the pressure relief mechanism and the first wall.

[0040] In a second aspect, a battery device is provided, comprising: a plurality of battery cells, the battery cell being the battery cell of the first aspect or any one of the embodiments of the first aspect.

[0041] In a third aspect, a power consuming device is provided, comprising: a battery device, the battery device comprising the battery cell of the first aspect or any one of the embodiments of the first aspect, the battery device being configured to supply power to the power consuming device.

[0042] In some embodiments, the power consuming device is a vehicle, a ship or a spacecraft. BRIEF DESCRIPTION OF DRAWINGS

[0043] FIG. 1 is a schematic view of a vehicle according to an embodiment of the present application;

[0044] FIG. 2 is an exploded structural schematic view of a battery device according to an embodiment of the present application;

[0045] FIG. 3 is a structural schematic view of a battery cell according to an embodiment of the present application;

[0046] FIG. 4 is a partially exploded structural schematic view of a battery cell according to an embodiment of the present application;

[0047] FIG. 5 is a partially exploded structural schematic view of a housing according to an embodiment of the present application;

[0048] FIG. 6 is a side view of a battery cell according to an embodiment of the present application;

[0049] FIG. 7 is a partially cutaway schematic view of a battery cell according to an embodiment of the present application;

[0050] FIG. 8 is another partially cutaway enlarged schematic view of a battery cell according to an embodiment of the present application;

[0051] FIG. 9 is a cutaway schematic view of a pressure relief mechanism during processing according to an embodiment of the present application;

[0052] FIG. 10 is a top view of a pressure relief mechanism during processing according to an embodiment of the present application;

[0053] FIG. 11 is a cutaway schematic view of a pressure relief mechanism during processing according to another embodiment of the present application;

[0054] Fig. 12 is a top view of a pressure relief mechanism of another embodiment of the application during processing;

[0055] Fig. 13 is a partial cross-sectional view of a first wall of a battery cell of one embodiment of the application;

[0056] Fig. 14 is a partial cross-sectional view of a battery cell of another embodiment of the application;

[0057] Fig. 15 is a partially exploded structural view of a housing of another embodiment of the application;

[0058] Fig. 16 is a side view of a battery cell of another embodiment of the application;

[0059] Fig. 17 is a partial cross-sectional view of a battery cell of another embodiment of the application;

[0060] Fig. 18 is another partial cross-sectional view of a battery cell of another embodiment of the application;

[0061] Fig. 19 is yet another partial cross-sectional view of a battery cell of another embodiment of the application;

[0062] Fig. 20 is a partial cross-sectional view of a battery cell of yet another embodiment of the application;

[0063] Fig. 21 is a partial cross-sectional view of a battery cell of yet another embodiment of the application;

[0064] Fig. 22 is a partial cross-sectional view of a battery cell of yet another embodiment of the application;

[0065] Fig. 23 is yet another partial cross-sectional view of a battery cell of one embodiment of the application;

[0066] Fig. 24 is a partial cross-sectional view of a protective member of another embodiment of the application;

[0067] Fig. 25 is a partial cross-sectional view of a protective member of yet another embodiment of the application;

[0068] Fig. 26 is a structural view of a protective member of one embodiment of the application;

[0069] Fig. 27 is a structural view of a protective member of another embodiment of the application;

[0070] Fig. 28 is a partial cross-sectional view of a protective member of another embodiment of the application;

[0071] Fig. 29 is another partial cross-sectional view of a protective member of another embodiment of the application.

[0072] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0073] The technical solutions in the embodiments of the present application will be described below with reference to the drawings.

[0074] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0075] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as those commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover the non-exclusive inclusion. The terms "first", "second", and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, and are not intended to describe a particular order or primary and secondary relationship.

[0076] In the present application, the phrase "embodiment" means that the specific features, structures, or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present application can be combined with other embodiments.

[0077] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", and "attach" should be understood broadly, for example, can be fixedly connected, or detachably connected, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0078] In the present application, the term "and / or" is only a description of the association relationship between the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0079] In the embodiments of the present application, the same reference signs represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of the present application shown in the drawings, and the overall thickness, length, width, and other dimensions of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0080] In the present application, "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).

[0081] In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging.

[0082] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel-hydrogen battery, a nickel-cadmium battery, a lead-acid battery, etc. The embodiments of the present application are not limited in this regard.

[0083] In some implementations, the battery cell in the embodiments of the present application can be a metal battery, specifically, the metal battery can include a lithium metal secondary battery, a sodium metal battery, or a magnesium metal battery, etc. The embodiments of the present application are not limited in this regard.

[0084] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of the battery cell, active ions (such as lithium ions) are inserted and extracted between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, which can prevent the positive and negative electrodes from short-circuiting, and at the same time, allow the active ions to pass through.

[0085] In some embodiments, the positive electrode can be a positive electrode sheet, which can include a positive electrode current collector and a positive electrode active material arranged on at least one surface of the positive electrode current collector.

[0086] As an example, the positive electrode current collector has two opposite surfaces in the thickness direction of itself, and the positive electrode active material is arranged on any one or both of the two opposite surfaces of the positive electrode current collector.

[0087] As an example, the positive electrode current collector can employ a metal foil, a foam metal, or a composite current collector. For example, as the metal foil, silver surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, or titanium, or the like can be employed. The foam metal can be a foam nickel, a foam copper, a foam aluminum, a foam alloy, or a foam carbon, or the like. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy, or the like) on a polymer material base material (a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, or the like).

[0088] As an example, the positive electrode active material can include at least one of a lithium-containing phosphate, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material can also be used. These positive electrode active materials can be used alone only one or two or more can be used in combination. Among them, examples of the lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFeP04 (which can also be referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnP04), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0089] In some embodiments, the negative electrode can be a negative electrode sheet, which can include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0090] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode active material is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0091] As an example, the negative electrode current collector can employ a metal foil, a foam metal, or a composite current collector. For example, as the metal foil, silver surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, or titanium, or the like can be employed. The foam metal can be a foam nickel, a foam copper, a foam aluminum, a foam alloy, or a foam carbon, or the like. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, a copper alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy, or the like) on a polymer material base material (a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, or the like).

[0092] As an example, the negative active material can employ a negative active material for a battery cell known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc.

[0093] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0094] In some embodiments, the separator is a separator film. The type of the separator film is not particularly limited in the present application, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0095] As an example, the main material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride, and ceramic.

[0096] In some embodiments, the separator is a solid-state electrolyte. The solid-state electrolyte is disposed between the positive electrode and the negative electrode, and functions to transport ions and separate the positive electrode and the negative electrode.

[0097] In some embodiments, the battery cell further includes an electrolyte, which functions to conduct ions between the positive electrode and the negative electrode. The type of the electrolyte is not particularly limited in the present application, and can be selected as needed. The electrolyte can be in a liquid state, a gel state, or a solid state.

[0098] In some embodiments, the electrode assembly has a jelly-roll structure. The positive electrode sheet and the negative electrode sheet are wound to have the jelly-roll structure.

[0099] In some embodiments, the electrode assembly has a stack structure.

[0100] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be alternately stacked.

[0101] As an example, a plurality of positive electrode sheets can be provided, and the negative electrode sheet can be folded to form a plurality of folded segments stacked one on another, with one positive electrode sheet interposed between adjacent folded segments.

[0102] As an example, both the positive electrode sheet and the negative electrode sheet can be folded to form a plurality of folded segments stacked one on another.

[0103] As an example, a plurality of separators can be provided, each interposed between any adjacent positive electrode sheet or negative electrode sheet.

[0104] As an example, the separators can be continuously provided, and can be interposed between any adjacent positive electrode sheet or negative electrode sheet by being folded or wound.

[0105] In some embodiments, the electrode assembly can have a cylindrical shape, a flat shape, or a polygonal shape, etc.

[0106] In some embodiments, the electrode assembly is provided with a tab, which can conduct current out of the electrode assembly. The tab includes a positive tab and a negative tab.

[0107] In some embodiments, the battery cell can include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing can be a steel case, an aluminum case, a plastic case (such as polypropylene), a composite metal case (such as a copper-aluminum composite case), or an aluminum-plastic film, etc. The housing includes a case body and a cover plate.

[0108] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes, including a square battery cell, a blade battery cell, a multi-prismatic battery cell (such as a hexagonal battery cell), etc., without particular limitation.

[0109] The battery device mentioned in the embodiments of the present application can include one or more battery cells to provide a single physical module with higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel, or in a mixed connection through a busbar component.

[0110] In some embodiments, the battery device can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0111] In some embodiments, the battery device can be a battery pack, which includes a box body and battery cells, and the battery cells or battery modules are accommodated in the box body.

[0112] In some embodiments, the box body can be part of the chassis structure of a vehicle. For example, part of the box body can be at least part of the floor of the vehicle, or part of the box body can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0113] The development of battery technology needs to consider various design factors, such as performance parameters such as energy density, cycle life, discharge capacity, and charge-discharge rate, in addition to safety. For a battery device, the main safety hazard comes from the charging and discharging process. In order to improve the safety performance of the battery device, a pressure relief mechanism is generally provided for the battery cell accommodated therein. The pressure relief mechanism refers to an element or component that is actuated to release the internal pressure or temperature of the battery cell when the internal pressure or temperature of the battery cell reaches a predetermined threshold.

[0114] And, in order to improve the energy density of the battery monomer, the shell of the battery monomer is usually thin, for example, a steel shell battery monomer can be used. The steel material can thin the thickness of the shell as much as possible while improving the structural strength of the shell of the battery monomer, thereby improving the energy density of the battery monomer. In the case of using a steel shell for the battery monomer, the battery monomer is prone to swelling during use, and the pressure relief mechanism is prone to fatigue cracking due to the swelling of the battery monomer, thereby reducing the service life of the battery monomer.

[0115] Therefore, the battery monomer, the battery device and the electric equipment provided by the embodiments of the present application can solve the above problems. The battery monomer provided by the embodiments of the present application comprises a shell, an electrode assembly and a pressure relief mechanism. The first wall of the shell is provided with a pressure relief hole, the electrode assembly is contained in the shell, and the pressure relief mechanism covers the pressure relief hole. The base material of the pressure relief mechanism is iron to improve the structural strength of the pressure relief mechanism. The pressure relief mechanism comprises a weak part, a body part and a connecting part. The weak part is configured to be destroyed to release the pressure when the pressure inside the shell reaches a threshold value. The body part is located in the area surrounded by the weak part. The connecting part is located outside the weak part and is used to connect the first wall. The body part is a protruding structure protruding towards the direction close to the electrode assembly or away from the electrode assembly.

[0116] During use of the battery monomer, the electrode assembly repeatedly swells and shrinks, and the weak part of the pressure relief mechanism is repeatedly stretched and shrunk, which is prone to fatigue. The body part protrudes relative to the weak part, and no matter the body part protrudes towards the inside or outside of the battery monomer, it can play a buffering role and can bear part of the stress, thereby reducing the deformation of the weak part and reducing the fatigue of the weak part. In addition, along the thickness direction of the pressure relief mechanism, the pressure inside the battery monomer repeatedly increases and decreases, and the middle region of the flat pressure relief mechanism will repeatedly protrude and recess towards the inside and outside of the battery monomer, which will also cause the weak part of the pressure relief mechanism to be repeatedly bent and prone to fatigue. When the body part protrudes relative to the weak part, no matter the body part protrudes towards the inside or outside of the battery monomer, the shape of the body part can be maintained, the bending angle of the weak part can be reduced, thereby reducing the fatigue of the weak part, improving the service life of the pressure relief mechanism, and further improving the service life of the battery monomer.

[0117] The technical solutions described in the embodiments of the present application are applicable to various electric equipment using battery devices.

[0118] The electric device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, and an electric tool, etc. The vehicle can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile, or a range extended automobile, etc. The spacecraft includes an airplane, a rocket, a space shuttle, a spacecraft, etc. The electric toy includes a fixed or mobile electric toy, such as a game machine, an electric automobile toy, an electric ship toy, and an electric airplane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, and an electric planer, etc. The electric device is not specially limited in the embodiments of the present application.

[0119] The following embodiments take the vehicle as an example for convenience of description.

[0120] For example, as shown in FIG. 1, a structural schematic diagram of a vehicle 1 according to an embodiment of the present application is shown. The vehicle 1 can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile, or a range extended automobile, etc. The vehicle 1 can be provided with a motor 40, a controller 30, and a battery device 10. The controller 30 is used to control the power supply of the motor 40 by the battery device 10. For example, the battery device 10 can be arranged at the bottom, the front, or the rear of the vehicle 1. The battery device 10 can be used for power supply of the vehicle 1. For example, the battery device 10 can be used as an operating power source of the vehicle 1, and is used for the circuit system of the vehicle 1, such as the power demand for starting, navigation, and operation of the vehicle 1. In another embodiment of the present application, the battery device 10 can not only be used as an operating power source of the vehicle 1, but also be used as a driving power source of the vehicle 1, to replace or partially replace the fuel or natural gas to provide driving power for the vehicle 1.

[0121] For example, FIG. 2 shows a partial structural schematic diagram of the battery device 10 according to an embodiment of the present application. As shown in FIG. 2, the battery device 10 according to an embodiment of the present application can include a plurality of battery monomers 20 to meet different power demands. The shape of the battery monomer 20 according to an embodiment of the present application can be set according to actual application. For example, the battery monomer 20 can be a cylinder as shown in FIG. 2, or can be a cuboid or other shape different from that shown in FIG. 2, which is not limited in the embodiments of the present application.

[0122] It should be understood that, as shown in FIG. 2, the battery device 10 of the embodiments of the present application can also include a box 11, which can be used to accommodate a plurality of battery cells 20. The box 11 of the embodiments of the present application is hollow inside, and the plurality of battery cells 20 are accommodated in the box 11. The box 11 can include two parts, which are referred to as a first box part 111 and a second box part 112 herein, and the first box part 111 and the second box part 112 are buckled together. The shapes of the first box part 111 and the second box part 112 can be determined according to the shapes of the components accommodated inside, for example, can be determined according to the shape of the combination of the plurality of battery cells 20 accommodated inside, and at least one of the first box part 111 and the second box part 112 has an opening. For example, as shown in FIG. 2, the first box part 111 and the second box part 112 can each be a hollow cuboid and each have an opening face, the opening of the first box part 111 and the opening of the second box part 112 are oppositely arranged, and the first box part 111 and the second box part 112 are buckled to each other to form a box 11 having a closed cavity, which can be used to accommodate the plurality of battery cells 20. The plurality of battery cells 20 combined in parallel or in series or in a hybrid manner are placed in the box 11 formed after the buckling of the first box part 111 and the second box part 112.

[0123] For another example, unlike that shown in FIG. 2, only one of the first box part 111 and the second box part 112 can be a hollow cuboid having an opening, and the other can be a plate-shaped to cover the opening. Taking the second box part 112 as a hollow cuboid having an opening and the first box part 111 as a plate-shaped as an example, the first box part 111 covers the opening of the second box part 112 to form a box 11 having a closed cavity, which can be used to accommodate the plurality of battery cells 20.

[0124] In some embodiments, the battery device 10 can also include other components. For example, the battery device 10 can also include a current collecting component, which can be used to achieve electrical connection between the plurality of battery cells 20, for example, in parallel or in series or in a hybrid manner. Specifically, the current collecting component can achieve electrical connection between the battery cells 20 by connecting the electrode terminals 214 of the battery cells 20; or the current collecting component can also achieve electrical connection between the battery cells 20 by connecting other components of the battery cells 20. The current collecting component can be fixed to the corresponding components of the battery cells 20 by welding, for example, can be fixed to the electrode terminals 214, the sealing structure or the shell, etc. by welding, and the embodiments of the present application are not limited thereto.

[0125] FIG. 3 shows a structural schematic diagram of a battery cell 20 according to an embodiment of the present application; FIG. 4 shows an exploded structural schematic diagram of a battery cell according to an embodiment of the present application, for example, the diagram of FIG. 4 can be an exploded structural schematic diagram of the battery cell 20 shown in FIG. 3; FIG. 5 shows a partial exploded structural schematic diagram of a battery cell 20 according to an embodiment of the present application, for example, the diagram of FIG. 5 can be a possible exploded structural schematic diagram of a housing 211 of the battery cell 20 shown in FIGS. 3 and 4; FIG. 6 shows a side view schematic diagram of a battery cell 20 according to an embodiment of the present application, for example, the diagram of FIG. 6 can be a side view schematic diagram of the battery cell 20 shown in FIGS. 3 to 5; FIG. 7 shows a partial cross-sectional schematic diagram of a battery cell 20 according to an embodiment of the present application, for example, the diagram of FIG. 7 can be a partial region of a cross-sectional view along the direction of A-A' shown in FIG. 6; FIG. 8 shows another partial cross-sectional schematic diagram of a battery cell 20 according to an embodiment of the present application, for example, FIG. 8 can be an enlarged view of region B shown in FIG. 7.

[0126] As shown in FIGS. 3 to 8, the battery cell 20 according to an embodiment of the present application can include a housing 211, an electrode assembly 22, and a pressure relief mechanism 213. Specifically, the housing 211 has a first wall 201 provided with a pressure relief hole 202; the electrode assembly 22 is accommodated in the housing 211; the pressure relief mechanism 213 covers the pressure relief hole 202, and a base material of the pressure relief mechanism 213 is iron; wherein the pressure relief mechanism 213 includes a weak portion 2132 configured to be broken to release pressure when the pressure inside the housing 211 reaches a threshold value, a body portion 2131 located in an area surrounded by the weak portion 2132, and a connecting portion 2133 located outside the weak portion 2132 and used to connect the first wall 201; and the body portion 2131 is a protruding structure protruding towards a direction close to the electrode assembly 22 or a direction away from the electrode assembly 22.

[0127] It should be understood that the shape of the battery cell 20 according to an embodiment of the present application can be flexibly set according to actual application, i.e., the outer shell 21 of the battery cell 20 can be any polyhedral structure, for example, can be set as a cuboid or a cylinder, etc. For example, as shown in FIGS. 3 to 8, the shape of the outside of the battery cell 20 can be the same as or different from the shape of the electrode assembly 22 inside. For example, if the electrode assembly 22 is a cylindrical structure, the outer shell 21 of the battery cell 20 can also be a cylindrical structure, or can also be a cuboid structure; if the electrode assembly 22 is a cuboid structure, the outer shell 21 can also be a cuboid structure in general, but the present application is not limited thereto.

[0128] In the embodiments of the present application, the battery cell 20 comprises a shell 211, for example, the outer shell 21 can comprise the shell 211. Specifically, the shell 211 is a hollow structure with an opening 2111, and the electrode assembly 22 is accommodated in the shell 211; the battery cell 20 can further comprise a cover plate 212, which is used to cover the opening 2111 of the shell 211 to isolate the external environment.

[0129] In some embodiments, the number of cover plates 212 is related to the opening 2111 of the shell 211. If the shell 211 is a hollow structure with an opening 2111 formed at one end, the cover plate 212 can be provided as one; or, as shown in FIGS. 3 to 8, the shell 211 can be a hollow structure with openings 2111 formed at both ends, so that the internal electrode assembly 22 can enter the shell from either side, providing installation efficiency, and the corresponding cover plate 212 can be provided as two, and the two cover plates 212 cover the openings 2111 at both ends of the shell 211, respectively, but the embodiments of the present application are not limited thereto.

[0130] The shapes of the shell 211 and the cover plate 212 of the embodiments of the present application match each other, for example, as shown in FIGS. 3 to 8, the shell 211 can be a cuboid structure, and the cover plate 212 can be a rectangular plate structure matched with the shell 211. The cover plate 212 can be any one wall of the outer shell 21, for example, the cover plate 212 can be the largest wall among the multiple walls included in the outer shell 21, or the smallest wall, or can also be other walls, and the embodiments of the present application are not limited thereto. Alternatively, the cover plate 212 can also be other structures, for example, the cover plate 212 can also be a groove structure with an opening, so as to cover the opening 2111 of the shell 211 with the opening of the cover plate 212, and the embodiments of the present application are not limited thereto.

[0131] In some embodiments, the first wall 201 can be any one wall of the shell 211 or the cover plate 212. For example, the first wall 201 is a side wall of the shell 211, that is, the first wall 201 can be a wall adjacent to the opening 2111, and the pressure relief mechanism 213 is arranged on the first wall 201. Especially in the case where the area of the cover plate 212 is limited, arranging the pressure relief mechanism 213 on the shell 211 can save the space of the cover plate 212 and facilitate processing.

[0132] For ease of illustration, the outer shell 21 is mainly taken as an approximate cuboid as shown in FIGS. 3 to 8; the shell 211 is a hollow structure with openings at opposite ends, and the first wall 201 is a side wall of the shell 211; correspondingly, two cover plates 212 are arranged to cover the two side openings 2111 of the shell 211, for example, the sealing connection between the shell 211 and the cover plate 212 can be achieved by welding, so as to form a closed cavity for placing the electrode assembly 22 and improve the sealing reliability.

[0133] In addition, for the rectangular battery monomer 20, three reference directions are defined for the convenience of description. The thickness direction of the battery monomer 20 is the direction Y, the height direction of the battery monomer 20 is the direction Z, and the length direction of the battery monomer 20 is the direction X, wherein the thickness direction Y, the height direction Z and the length direction X of the battery monomer 20 are perpendicular to each other, and the thickness direction Y of the battery monomer 20 is smaller than the length direction X.

[0134] In the embodiment of the present application, the first wall 201 is provided with a pressure relief hole 202, and the pressure relief hole 202 is covered by the pressure relief mechanism 213. The first wall 201 is provided with a pressure relief hole 202, that is, a through hole is arranged on the first wall 201 as the pressure relief hole 202, which is convenient for processing; and the pressure relief mechanism 213 which is separately arranged from the first wall 201 is more flexible and convenient for processing and assembly, which can improve the design flexibility of the pressure relief mechanism 213.

[0135] It should be understood that the pressure relief mechanism 213 of the embodiment of the present application refers to an element or component that is actuated when the internal pressure or temperature of the battery monomer 20 reaches a predetermined threshold value to release the internal pressure or temperature. The threshold value is designed differently according to different design requirements. The threshold value can depend on the material of one or more of the positive electrode sheet, the negative electrode sheet, the electrolyte and the separator in the battery monomer 20.

[0136] The "actuation" mentioned in the present application refers to the action or activation of the pressure relief mechanism 213 to a certain state, so that the internal pressure and temperature of the battery monomer 20 can be released. The action generated by the pressure relief mechanism 213 can include but is not limited to: at least part of the pressure relief mechanism 213 is broken, broken, torn or opened, etc. When the pressure relief mechanism 213 is actuated, the high-temperature and high-pressure substances inside the battery monomer 20 will be discharged outward from the actuated part as the discharge. In this way, the battery monomer 20 can be relieved of pressure and temperature under controllable pressure or temperature, thereby avoiding potential more serious accidents.

[0137] The discharge from the battery monomer 20 mentioned in the present application includes but is not limited to: electrolyte, dissolved or split positive and negative electrode sheets, fragments of the separator, high-temperature and high-pressure gas generated by the reaction, flame, etc.

[0138] It should be understood that the base material of the pressure relief mechanism 213 of the embodiment of the present application is iron, and "base material" here refers to the material with the highest weight percentage in the material of the pressure relief mechanism 213. For example, the material of the pressure relief mechanism 213 can include at least one of: iron-carbon alloy, stainless steel, cast iron and alloy steel, etc., to improve the structural strength of the pressure relief mechanism 213.

[0139] It should be understood that the pressure relief mechanism 213 of the embodiment of the present application includes a weak portion 2132 configured to be broken to release the pressure when the pressure inside the shell 211 reaches a threshold value, and the weak portion 2132 can be implemented in various ways. For example, the weak portion 2132 can be a notch or a groove, so that the thickness of the weak portion 2132 is smaller than the thickness of other regions of the pressure relief mechanism 213, thereby reducing the structural strength of the weak portion 2132, so that the weak portion 2132 is more easily broken. For another example, the weak portion 2132 can also be provided with a temperature-sensitive material, so that when the temperature inside the battery monomer 20 exceeds a threshold value, the weak portion 2132 is easily broken. For the convenience of description, the embodiment mainly takes the notch as an example to illustrate the weak portion 2132.

[0140] It should be understood that the position of the weak portion 2132 of the pressure relief mechanism 213 of the embodiment of the present application can be set according to actual application. For example, the weak portion 2132 can be annular, and the weak portion 2132 can be continuously and circumferentially arranged at the edge of the pressure relief mechanism 213, so that the weak portion 2132 is uniformly distributed, and when the battery monomer 20 occurs thermal runaway, any region of the annular weak portion 2132 can be broken, so that the pressure relief mechanism 213 timely discharges the exhaust inside the battery monomer 20, reduces the risk of thermal diffusion between the plurality of battery monomers 20, and improves the reliability of the battery device 10.

[0141] The pressure relief mechanism 213 of the embodiment of the present application also includes a body portion 2131 located in the region surrounded by the weak portion 2132, and a connecting portion 2133 located outside the weak portion 2132 and used to connect the first wall 201; the body portion 2131 is a protruding structure towards the direction close to the electrode assembly 22 or the direction away from the electrode assembly 22.

[0142] The body portion 2131 of the embodiment of the present application is a protruding structure towards the direction close to the electrode assembly 22 or the direction away from the electrode assembly 22, that is, the body portion 2131 is uneven. For example, all regions of the body portion 2131 are protruding structures towards the direction close to the electrode assembly 22; or all regions of the body portion 2131 are protruding structures towards the direction away from the electrode assembly 22; or a part of the regions of the body portion 2131 are protruding structures towards the direction close to the electrode assembly 22, and a part of the regions of the body portion 2131 are protruding structures towards the direction away from the electrode assembly 22, for example, the body portion 2131 can be a wave-shaped structure, and the embodiment of the present application is not limited thereto.

[0143] The body part 2131 is provided as a raised structure, which can effectively improve the service life of the pressure relief mechanism 213. FIG. 9 shows a cross-sectional view of the pressure relief mechanism 213 according to an embodiment of the application, and FIG. 10 shows a top view of the pressure relief mechanism 213 according to an embodiment of the application. For example, FIGS. 9 and 10 can be the pressure relief mechanism 213 included in the battery monomer 20 shown in FIGS. 3 to 8. FIG. 11 shows a cross-sectional view of another pressure relief mechanism 213', and FIG. 12 shows a top view of the pressure relief mechanism 213'.

[0144] As shown in FIGS. 11 and 12, for the relatively flat pressure relief mechanism 213', when the base material is iron, the structural strength of the pressure relief mechanism 213' is large. In the process of forming the notch by stamping, the notch is formed around the area subjected to the extrusion force F towards the center of the pressure relief mechanism 213'. Due to the difficulty of metal flow, the direction distribution of the deformation amount S of different areas around the area where the notch is formed is uneven. Some areas are raised towards the direction close to the electrode assembly 22 under the action of the extrusion force F, and some areas are raised towards the direction away from the electrode assembly 22 under the action of the extrusion force F. The originally flat pressure relief mechanism 213' becomes uneven, which leads to poor consistency of the explosion of the pressure relief mechanism 213' and affects the safety and reliability of the battery device 10.

[0145] As shown in FIGS. 9 and 10, the body part 2131 of the pressure relief mechanism 213 according to an embodiment of the application is a raised structure. Whether the body part 2131 protrudes towards the inside or outside of the battery monomer 20, the strength of the pressure relief mechanism 213 can be enhanced. In the process of stamping the notch, the body part 2131 is subjected to the extrusion force F towards the center of the pressure relief mechanism 213. Different areas of the body part 2131 are deformed along the direction of the raised structure, and the direction of the deformation amount S is consistent. Therefore, the overall shape of the pressure relief mechanism 213 is stable, which guarantees the consistency of the explosion of the pressure relief mechanism 213.

[0146] In addition, during use of the battery monomer 20, the electrode assembly 22 repeatedly expands and shrinks, the weak portion 2132 of the pressure relief mechanism 213 is repeatedly pulled and shrunk, and fatigue is prone to occur; the body portion 2131 protrudes relative to the weak portion 2132, and no matter whether the body portion 2131 protrudes towards the inside or outside of the battery monomer 20, the body portion 2131 can play a buffering role and can bear part of the stress, thereby reducing the deformation of the weak portion 2132 and reducing the fatigue of the weak portion 2132. Moreover, along the thickness direction X of the pressure relief mechanism 213, the pressure inside the battery monomer 20 repeatedly increases and decreases, and the middle region of the flat pressure relief mechanism 213' repeatedly protrudes and recesses towards the inside and outside of the battery monomer 20, which also causes the weak portion of the pressure relief mechanism 213' to be repeatedly bent and prone to fatigue; in the case where the body portion 2131 of the embodiment of the present application protrudes relative to the weak portion 2132, no matter whether the body portion 2131 protrudes towards the inside or outside of the battery monomer 20, the shape of the body portion 2131 can be relatively stable, the bending angle of the weak portion 2132 is reduced, and thus the fatigue of the weak portion 2132 is reduced, the service life of the pressure relief mechanism 213 is improved, and thus the service life of the battery monomer 20 is improved.

[0147] It should be understood that the base material of the pressure relief mechanism 213 of the embodiment of the present application is iron, and the specific material thereof can be set according to actual application. For example, the material of the pressure relief mechanism 213 includes stainless steel and / or carbon steel. The pressure relief mechanism 213 made of stainless steel has large structural strength and can also prevent corrosion and rust, thereby effectively improving the service life of the pressure relief mechanism 213. The pressure relief mechanism 213 made of carbon steel has greater structural strength, which is conducive to improving the structural stability and reliability of the pressure relief mechanism 213. For another example, the material of the pressure relief mechanism 213 is selected to be steel, and the model of the steel can include at least one of SPCC, Q195, Q215, Q235, SUS 304, SUS 316 and other modified stainless steels. These steels are easy to obtain, the strength thereof is easy to meet the design requirements of the battery monomer 20, and the cost is relatively low.

[0148] In the embodiment of the present application, the material of the shell 211 of the embodiment of the present application can include one or more kinds, such as copper, iron, aluminum, steel, aluminum alloy and the like. The material of the cover plate 212 can also be one or more kinds, such as copper, iron, aluminum, steel, aluminum alloy and the like. The material of the cover plate 212 can be the same as or different from the material of the shell 211, and the materials of different walls of the shell 211 can also be the same or different.

[0149] In some embodiments, the base material of the shell 211 is iron to improve the structural strength of the shell 211, where the "base material" refers to the material with the highest weight percentage among the materials of the shell 211. The specific material of the shell 211 can be set according to actual application. For example, the material of at least a portion of the shell 211 can include at least one of stainless steel, carbon steel, and high-strength alloy steel. For another example, in the case where the material of the shell 211 includes steel, the model of the steel can include at least one of SPCC, Q195, Q215, Q235, SUS 304, SUS 316, and other modified stainless steel. These steels are easy to obtain, have strength that is easy to meet the design requirements of the battery cell 20, and are low in cost.

[0150] It should be understood that the thickness T1 of the shell 211 of the embodiments of the present application can be set according to actual application. For example, the thickness of the shell 211 can be in the range of [0.075 mm, 0.4 mm]; for another example, the thickness of the shell 211 can be in the range of [0.075 mm, 0.25 mm]. On the one hand, the thickness T1 of the shell 211 is set to be greater than or equal to 0.075 mm, which is easy to process and can improve the structural strength of the shell 211, thereby improving the structural stability of the battery cell 20. On the other hand, the thickness T1 of the shell 211 is set to be less than or equal to 0.4 mm, or further, the thickness T1 of the shell 211 is set to be less than or equal to 0.25 mm, which can reduce the volume of the battery cell 20, and can effectively reduce the weight of the battery cell 20 and improve the energy density of the battery cell 20. For example, the material of the shell 211 can include steel to facilitate the design requirements of the thickness T1 of the shell 211.

[0151] In some embodiments, the thickness of the shell 211 can be any of the following values or between any two of the following values: 0.075 mm, 0.1 mm, 0.125 mm, 0.15 mm, 0.175 mm, 0.2 mm, 0.225 mm, 0.25 mm, 0.275 mm, 0.3 mm, 0.325 mm, 0.35 mm, 0.375 mm, and 0.4 mm.

[0152] It should be understood that the thickness T1 of the shell 211 in the embodiments of the present application can refer to the average thickness of at least a partial region of the shell 211. For example, the thickness T1 of the shell 211 can refer to the average thickness of the entire region of the shell 211, especially in the case that the shell 211 is relatively flat and the thickness is relatively uniform, that is, the thickness of most regions of the shell 211 is substantially equal or has a small difference, or the thickness of the entire region of the shell 211 is substantially equal or has a small difference, and then the average thickness of the entire region of the shell 211 can be determined as T1. Alternatively, the thickness T1 of the shell 211 can also refer to the average thickness of a local region of the shell 211, for example, the thickness of the first wall 201 of the shell 211, or the average thickness of a local region of the first wall 201 close to the pressure relief mechanism 213, and the embodiments of the present application are not limited thereto.

[0153] It should be understood that the thickness of the pressure relief mechanism 213 in the embodiments of the present application can be set according to actual application. For example, the thickness T2 of the body part 2131 is in the range of [0.075mm, 0.4mm]; for another example, the thickness T2 of the body part 2131 is in the range of [0.075mm, 0.25mm]. On the one hand, the thickness T2 of the body part 2131 is greater than or equal to 0.075mm, which is convenient for processing and can improve the structural strength of the pressure relief mechanism 213 as a whole, thereby improving the structural stability of the battery monomer 20. On the other hand, the thickness T2 of the body part 2131 is less than or equal to 0.4mm, or further, the thickness T2 of the body part 2131 is less than or equal to 0.25mm, which can reduce the volume occupied by the pressure relief mechanism 213, and can effectively reduce the weight of the battery monomer 20 and improve the energy density of the battery monomer 20.

[0154] In some embodiments, the thickness T2 of the body part 2131 can be any of the following values or between any two of the following values: 0.075mm, 0.1mm, 0.125mm, 0.15mm, 0.175mm, 0.2mm, 0.225mm, 0.25mm, 0.275mm, 0.3mm, 0.325mm, 0.35mm, 0.375mm and 0.4mm.

[0155] The thickness T2 of the body part 2131 in the embodiments of the present application can be the average thickness of the body part 2131. The body part 2131 is the middle region of the pressure relief mechanism 213, and the thickness thereof is generally uniform, so the thickness of different regions of the body part 2131 can be set to be the same or substantially the same, and then the average thickness of the body part 2131 is the thickness T2 of the body part 2131.

[0156] In some embodiments, the thickness of the weak portion 2132 of the embodiments of the present application can be set according to actual application. For example, taking the notch as the weak portion 2132, the minimum thickness T0 of the notch ranges from 8 μm to 100 μm. The minimum thickness T0 of the notch is greater than or equal to 8 μm, so as to improve the structural strength of the pressure relief mechanism 213 in the case of normal use of the battery monomer 20, and reduce the risk of premature cracking of the pressure relief mechanism 213. The minimum thickness T0 of the notch is less than or equal to 100 μm, so that the notch can be damaged in time when the battery monomer 20 is in thermal runaway, so as to quickly release the pressure and temperature inside the battery monomer 20, reduce the risk of thermal diffusion, and improve the reliability of the battery device 10.

[0157] In some embodiments, the minimum thickness T0 of the notch can be equal to any of the following values or between any two of the following values: 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 23 μm, 25 μm, 28 μm, 30 μm, 33 μm, 35 μm, 38 μm, 40 μm, 43 μm, 45 μm, 48 μm, 50 μm, 53 μm, 55 μm, 58 μm, 60 μm, 63 μm, 65 μm, 68 μm, 70 μm, 73 μm, 75 μm, 78 μm, 80 μm, 83 μm, 85 μm, 88 μm, 90 μm, 93 μm, 95 μm, 98 μm, and 100 μm.

[0158] It should be understood that the specific shape of the pressure relief mechanism 213 of the embodiments of the present application can be set according to actual application. In some embodiments, the body portion 2131 can be an arched structure to facilitate processing, and during use of the battery monomer 20, the battery monomer 20 will swell during charging and discharging, for example, when the battery monomer 20 repeatedly swells and deforms in the direction parallel to the first wall 201 and the direction perpendicular to the first wall 201, the arched body portion 2131 can effectively absorb the deformation amount, improve the structural strength and fatigue resistance of the pressure relief mechanism 213, and further improve the service life of the pressure relief mechanism 213.

[0159] In some embodiments, the position of the arched body portion 2131 can be related to the electrode assembly 22 in the housing. Specifically, the electrode assembly 22 includes at least two layers of tabs; the at least two layers of tabs are stacked, the stacking direction of the at least two layers of tabs is the first direction Y; or, the at least two layers of tabs are wound, the at least two layers of tabs each include a planar section at the middle of the electrode assembly 22 and a curved section at both ends of the electrode assembly 22, and the stacking direction of the at least two layers of tabs at the planar section is the first direction Y; the cross section of the body portion 2131 in at least one plane perpendicular to the first direction Y is arched, for example, in the embodiments of the present application, the first direction Y is taken as the thickness direction Y of the battery monomer 20. By setting the cross section of the body portion 2131 in at least one plane perpendicular to the first direction Y to be arched, the deformation of the electrode assembly 22 can be effectively absorbed, the deformation capacity of the pressure relief mechanism 213 can be improved, and the service life of the pressure relief mechanism 213 can be further improved.

[0160] Further, considering that the deformation amount of the electrode assembly 22 along the first direction Y is usually large during the use of the battery monomer 20, whether it is a wound electrode assembly 22 or a stacked electrode assembly 22, the cross section of the body portion 2131 in at least one plane parallel to the first direction Y can also be arched, for example, the at least one plane can be perpendicular to the height direction Z of the battery monomer 20, and the cross section of the body portion 2131 is arched as shown in FIG. 7, which can effectively absorb the deformation of the electrode assembly 22, further improve the deformation capacity of the pressure relief mechanism 213, and further improve the service life of the pressure relief mechanism 213 and the battery monomer 20.

[0161] It should be understood that the electrode assembly 22 of the embodiments of the present application is a component that undergoes an electrochemical reaction in the battery monomer 20, and according to actual use requirements, the electrode assembly 22 in the battery monomer 20 can be one or more. For any one electrode assembly 22, the electrode assembly 22 can include a tab 222 and a tab main body portion 221. Specifically, the electrode assembly 22 can include at least two tabs 222, which can include at least one positive tab and at least one negative tab, the positive tab can be formed by stacking the portion of the positive tab that is not coated with a positive active material layer, and the portion of the positive tab that is coated with a positive active material layer can be formed into a tab main body portion 221 by winding or stacking; the negative tab can be formed by stacking the portion of the negative tab that is not coated with a negative active material layer, and the portion of the negative tab that is coated with a negative active material layer can be formed into a tab main body portion 221 by winding or stacking.

[0162] The plurality of tabs 222 of the electrode assembly 22 of the embodiments of the present application can be located on the same or different end faces of the electrode assembly 22. For example, the electrode assembly 22 can include two tabs 222 of opposite polarity, which can be located on the same end face, or which can be arranged on different end faces, for example, the two tabs 222 can be located on opposite end faces, and the embodiments of the present application are not limited thereto. For ease of illustration, as shown in FIGS. 3 to 8, the embodiments of the present application mainly take the example that the electrode assembly 22 includes two tabs 222 of opposite polarity located on opposite end faces of the electrode assembly 22.

[0163] In some embodiments, the housing 21 of the battery cell 20 of the embodiments of the present application can further be provided with an electrode terminal 214 for electrically connecting with the electrode assembly 22 to output the electrical energy of the battery cell 20. The battery cell 20 can include at least two electrode terminals 214, including at least one positive electrode terminal and at least one negative electrode terminal. Each electrode terminal 214 is used to electrically connect with a corresponding tab 222. For example, each electrode terminal 214 can be electrically connected with a corresponding tab 222 through a connecting member. For example, the positive tab of the electrode assembly 22 can be connected with the positive electrode terminal through one connecting member, and the negative tab of the electrode assembly 22 can be connected with the negative electrode terminal through another connecting member.

[0164] The at least two electrode terminals 214 of the battery cell 20 can be arranged on the same wall or different walls of the battery cell 20. For example, the position of the electrode terminal 214 can be arranged according to the position of the tab 222 of the electrode assembly 22. For example, as shown in FIGS. 3 to 8, the embodiments of the present application mainly take the example that the battery cell 20 includes two electrode terminals 214 arranged on opposite two walls of the housing 21 of the battery cell 20.

[0165] It should be understood that the protruding height of the body portion 2131 of the embodiment of the present application can be set according to actual application. For example, the protruding height H of the body portion 2131 relative to the weak portion 2132 is in the range of [0.5mm, 4mm]; for another example, the protruding height H of the body portion 2131 relative to the weak portion 2132 is in the range of [0.8mm, 2mm]. Setting the protruding height H of the body portion 2131 relative to the weak portion 2132 to be greater than or equal to 0.5mm, or further, setting the protruding height H of the body portion 2131 relative to the weak portion 2132 to be greater than or equal to 0.8mm, can make the body portion 2131 effectively absorb the deformation amount, improve the structural stability of the body portion 2131; setting the protruding height H of the body portion 2131 relative to the weak portion 2132 to be less than or equal to 4mm, or further, setting the protruding height H of the body portion 2131 relative to the weak portion 2132 to be less than or equal to 2mm, can limit the space occupied by the body portion 2131, and further limit the space occupied by the pressure relief mechanism 213, improve the space utilization of the battery monomer 20, and further improve the energy density of the battery monomer 20.

[0166] In some embodiments, the protruding height H of the body portion 2131 relative to the weak portion 2132 can be equal to any of the following values or between any two of the following values: 0.5mm, 0.8mm, 1mm, 1.3mm, 1.5mm, 1.8mm, 2mm, 2.3mm, 2.5mm, 2.8mm, 3mm, 3.3mm, 3.5mm, 3.8mm and 4mm.

[0167] It should be understood that the protruding direction of the body portion 2131 of the embodiment of the present application can be set according to actual application. For example, as shown in FIGS. 3-8, the connecting portion 2133 includes a fixed area 2135 and a transition area 2136, the fixed area 2135 is used to connect with the first wall 201, the transition area 2136 is used to connect the fixed area 2135 and the weak portion 2132, the fixed area 2135 is arranged in parallel relative to the first wall 201, and the transition area 2136 and the body portion 2131 are both protruded relative to the weak portion 2132 in a direction away from the electrode assembly 22.

[0168] When the battery monomer 20 is working normally, the internal gas pressure or temperature of the battery monomer 20 is low. The following is illustrated by taking the gas pressure as an example. The gas pressure inside the battery monomer 20 continuously acts on the pressure relief mechanism 213, so that the body portion 2131, the weak portion 2132 and the transition area 2136 move upward or have a tendency to move upward, and the body portion 2131 has a tendency to reduce the contour circumference and shrink to the center.

[0169] As the transition region 2136 is inclined towards the interior of the battery cell 20, the position of the weak portion 2132 is closer to the interior of the battery cell 20 than the fixed region 2135, that is, the position of the weak portion 2132 is closer to the interior of the battery cell 20 than the fixed position of the pressure relief mechanism 213 and the cover plate 212. Moreover, as one end of the transition region 2136 is constrained by the fixed region 2135, under the action of the gas pressure, the end of the transition region 2136 extending towards the interior of the battery cell 20 will press the weak portion 2132 in the direction of the weak portion 2132, thereby inhibiting the cracking of the weak portion 2132 and reducing the risk of creep failure of the pressure relief mechanism 213 when the battery cell 20 is working normally, effectively prolonging the service life of the pressure relief mechanism 213. On the other hand, the outwardly protruding body portion 2131 can support the transition region 2136 and the weak portion 2132, and can effectively press the weak portion 2132.

[0170] When the gas pressure or temperature inside the battery cell 20 continues to rise until it is greater than or equal to a predetermined value, the battery cell 20 can be about to undergo thermal runaway, and the transition region 2136 can be flipped from the state of extending towards the interior of the battery cell 20 to the state of extending away from the interior of the battery cell 20. Specifically, when the gas pressure or temperature inside the battery cell 20 rises to or exceeds the predetermined value, the transition region 2136, the weak portion 2132 and the body portion 2131 as a whole continue to move upwards, wherein the transition region 2136 deforms greatly, flips from the state of extending towards the interior of the battery cell 20 to the state of extending away from the interior of the battery cell 20. More specifically, the part of the transition region 2136 adjacent to the weak portion 2132 becomes the state of extending away from the interior of the battery cell 20, while the part adjacent to the fixed region 2135 is constrained by the fixed region 2135 and moves relatively less. After the transition region 2136 is flipped, the transition region 2136 basically becomes the state of extending away from the interior of the battery cell 20 as a whole, and the transition region 2136 changes from the state of pressing the weak portion 2132 to the state of stretching the weak portion 2132, promoting the cracking of the weak portion 2132 and helping to achieve rapid pressure relief. On the other hand, the body portion 2131 moves upwards under the action of the gas pressure, also stretching the weak portion 2132, promoting the cracking of the weak portion 2132 and helping to achieve rapid pressure relief.

[0171] It should be understood that the fixed area 2135 of the embodiment of the present application is used to be connected with the first wall 201, for example, the first wall 201 can include a first fixed area 203, and the first fixed area 203 is used to be fixedly connected with the fixed area 2135 to realize the fixed connection between the pressure relief mechanism 213 and the first wall 201. The fixed area 2135 of the embodiment of the present application is arranged in parallel with respect to the first wall 201, for example, the fixed area 2135 can be a plate-shaped structure, that is, the fixed area 2135 is relatively flat, rather than a concave-convex or inclined area, so as to be fixedly connected with the first fixed area 203 of the first wall 201 which is also relatively flat.

[0172] In the embodiment of the present application, for the case that the body part 2131 and the transition area 2136 both protrude in the direction away from the electrode assembly 22, the surface of the pressure relief mechanism 213 away from the inside of the battery monomer 20 does not exceed the surface of the first wall 201 away from the inside of the battery monomer 20, so as to reduce the case that the pressure relief mechanism 213 contacts the external components and is abraded, and improve the service life of the pressure relief mechanism 213. As shown in FIGS. 3 to 8, the surface of the pressure relief mechanism 213 away from the inside of the battery monomer 20 does not exceed the surface of the first wall 201 away from the inside of the battery monomer 20 includes that on the side away from the inside of the battery monomer 20, the outermost surface of the first wall 201 is flush with the outermost surface of the pressure relief mechanism 213, or the outermost surface of the first wall 201 exceeds the outermost surface of the pressure relief mechanism 213.

[0173] It should be understood that the surface of the pressure relief mechanism 213 away from the inside of the battery monomer 20 does not exceed the surface of the first wall 201 away from the inside of the battery monomer 20 can be realized in various ways. For example, the surface of the pressure relief mechanism 213 away from the inside of the battery monomer 20 does not exceed the surface of the first wall 201 away from the inside of the battery monomer 20 can be realized by providing a groove on the pressure relief mechanism 213 and / or the first wall 201.

[0174] In some embodiments, the pressure relief mechanism 213 includes a first groove 2134 recessed toward the inside of the battery monomer 20, the bottom wall of the first groove 2134 includes the weak part 2132, part of the side wall of the first groove 2134 is the transition area 2136, and the other part of the side wall of the first groove 2134 is at least part of the area of the body part 2131. The body part 2131 and the transition area 2136 both protrude in the direction away from the electrode assembly 22 through the first groove 2134, and the surface of the pressure relief mechanism 213 away from the inside of the battery monomer 20 does not exceed the surface of the first wall 201 away from the inside of the battery monomer 20. In addition, the pressure relief mechanism 213 is provided with the first groove 2134 recessed toward the inside of the battery monomer 20, and the first groove 2134 can be used to absorb the expansion amount in the direction parallel to the surface of the first wall 201, so as to improve the structural strength of the pressure relief mechanism 213.

[0175] In some embodiments, the first wall 201 is provided with a second groove 204 recessed towards the inside of the battery monomer 20, and the pressure relief mechanism 213 is located at the bottom wall of the second groove 204. FIG. 13 shows a partial cross-sectional view of the first wall 201 of an embodiment of the present application, for example, FIG. 13 can be a partial cross-sectional view of the first wall 201 in FIG. 7. In the embodiments of the present application, as shown in FIGS. 3 to 13, the first wall 201 is provided with a second groove 204, by setting the depth of the second groove 204, at least part of the pressure relief mechanism 213 can be located in the second groove 204, for example, the protruding body part 2131 of the pressure relief mechanism 213 can be located in the second groove 204, so that the surface of the pressure relief mechanism 213 away from the inside of the battery monomer 20 does not exceed the surface of the first wall 201 away from the inside of the battery monomer 20, so as to protect the pressure relief mechanism 213 and improve the service life of the pressure relief mechanism 213.

[0176] In some embodiments, the body part 2131 can also protrude towards the direction of the electrode assembly 22. FIG. 14 shows a partial cross-sectional view of a battery monomer 20 of another embodiment of the present application, for example, the direction of the cross-sectional view shown in FIG. 14 is consistent with the direction of the cross-sectional view shown in FIG. 7, that is, FIG. 14 shows a partial cross-sectional view of the battery monomer 20 different from that shown in FIG. 7.

[0177] As shown in FIG. 14, the connecting part 2133 includes a fixed area 2135 and a transition area 2136, the fixed area 2135 is used to connect with the first wall 201, the transition area 2136 is used to connect the fixed area 2135 with the weak part 2132, the fixed area 2135 is arranged in parallel with respect to the first wall 201, and the transition area 2136 protrudes towards the direction close to the electrode assembly 22 with respect to the fixed area 2135; the body part 2131 protrudes towards the direction close to the electrode assembly 22 with respect to the fixed area 2135, that is, the transition area 2136, the weak part 2132 and the body part 2131 all protrude towards the direction close to the electrode assembly 22.

[0178] When the battery monomer 20 is working normally, the internal pressure or temperature of the battery monomer 20 is low. The following is illustrated by taking the internal pressure as an example. The internal pressure of the battery monomer 20 continuously acts on the pressure relief mechanism 213, so that the transition area 2136, the weak part 2132 and the body part 2131 move upward or have a tendency to move upward, and the transition area 2136, the weak part 2132 and the body part 2131 as a whole shrink towards the center with a reduced contour circumference.

[0179] As shown in FIG. 14, due to the inclination of the transition region 2136 towards the inside of the battery cell 20, the position of the weak portion 2132 is closer to the inside of the battery cell 20 than the position of the fixed region 2135, that is, the position of the weak portion 2132 is closer to the inside of the battery cell 20 than the position of the fixing of the pressure relief mechanism 213 and the cover plate 212. Moreover, due to the constraint of the fixed region 2135 on one end of the transition region 2136, the end of the transition region 2136 extending towards the inside of the battery cell 20 extrudes the weak portion 2132 in the direction of the weak portion 2132, thereby inhibiting the cracking of the weak portion 2132, reducing the risk of creep failure of the pressure relief mechanism 213 during normal operation of the battery cell 20, and effectively prolonging the service life of the pressure relief mechanism. Similarly, the body portion 2131 moves upward under the action of gas pressure, and the end of the body portion 2131 close to the weak portion 2132 extrudes the weak portion 2132 in the direction of the weak portion 2132, which can also inhibit the cracking of the weak portion 2132, reduce the risk of creep failure of the pressure relief mechanism 213 during normal operation of the battery cell 20, and effectively prolong the service life of the pressure relief mechanism 213.

[0180] When the internal gas pressure or temperature of the battery cell 20 continues to rise and reaches or exceeds a predetermined value, the battery cell 20 may be about to have thermal runaway, and the transition region 2136, the weak portion 2132 and the body portion 2131 as a whole continue to move upward, wherein the body portion 2131 deforms greatly and may be flipped from a downward protruding shape to an upward protruding shape. At this time, the middle region of the body portion 2131 moves above the weak portion 2132, and the transition region 2136 is constrained by the fixed region 2135 and moves little. After the body portion 2131 is flipped, the body portion 2131 as a whole moves above the weak portion 2132, and the body portion 2131 changes from the state of extruding the weak portion 2132 to the state of stretching the weak portion 2132, thereby promoting the cracking of the weak portion 2132 and facilitating rapid pressure relief.

[0181] In some embodiments, unlike shown in FIG. 14, the transition region 2136 of the embodiments of the present application can also not be protruding. For example, the fixed region 2135 is arranged parallel to the first wall 201, the transition region 2136 is flush with the fixed region 2135, and the body portion 2131 protrudes towards the direction close to the electrode assembly 22 relative to the fixed region 2135, that is, the body portion 2131 protrudes towards the direction close to the electrode assembly 22 relative to the fixed region 2135, and the weak portion 2132 is not protruding with the transition region 2136.

[0182] When the battery cell 20 is in normal operation, the internal pressure or temperature of the battery cell 20 is low. The following is described by taking the internal pressure as an example. The internal pressure of the battery cell 20 continuously acts on the pressure relief mechanism 213, causing the body portion 2131 to move upward or have a tendency to move upward, and the body portion 2131 to shrink toward the center and reduce the profile circumference. The body portion 2131 moves upward under the action of the internal pressure, and the end of the body portion 2131 close to the weak portion 2132 presses the weak portion 2132 toward the weak portion 2132, which can inhibit the cracking of the weak portion 2132 and reduce the risk of creep failure of the pressure relief mechanism 213 when the battery cell 20 is in normal operation, effectively prolonging the service life of the pressure relief mechanism 213.

[0183] When the internal pressure or temperature of the battery cell 20 continuously rises and reaches or exceeds a predetermined value, the battery cell 20 may be about to have thermal runaway, and the body portion 2131 as a whole continues to move upward and may be deformed greatly, and then flips from the downwardly convex shape to the upwardly convex shape. At this time, the middle region of the body portion 2131 moves above the weak portion 2132, and the transition region 2136 moves little due to the constraint of the fixed region 2135. After the body portion 2131 is flipped, the body portion 2131 as a whole moves above the weak portion 2132, and the body portion 2131 changes from the state of pressing the weak portion 2132 to the state of stretching the weak portion 2132, thereby promoting the cracking of the weak portion 2132 and facilitating rapid pressure relief.

[0184] It should be understood that in the above embodiment, if the transition region 2136 protrudes toward the direction close to the electrode assembly 22 relative to the fixed region 2135, the inclination angle thereof can be set according to actual application. For example, as shown in FIGS. 3 to 14, the transition region 2136 protrudes toward the direction close to the electrode assembly 22 relative to the fixed region 2135, and the inclination angle θ of the transition region 2136 relative to the fixed region 2135 is in the range of [40°, 75°]. Setting the inclination angle θ of the transition region 2136 relative to the fixed region 2135 to be greater than or equal to 40° can control the bending degree between the transition region 2136 and the fixed region 2135 not to be too large, reduce the stress concentration in the region between the transition region 2136 and the fixed region 2135, and improve the structural strength; and setting the inclination angle θ of the transition region 2136 relative to the fixed region 2135 to be less than or equal to 75° can control the bending degree between the transition region 2136 and the fixed region 2135 not to be too small, and in the case that the body portion 2131 protrudes away from the electrode assembly 22 as shown in FIGS. 3 to 8 and in the case that the body portion 2131 protrudes toward the direction close to the electrode assembly 22 as shown in FIG. 14, the risk of creep failure of the pressure relief mechanism 213 when the battery cell 20 is in normal operation can be reduced, the service life of the pressure relief mechanism 213 can be effectively prolonged, and the cracking of the weak portion 2132 can be promoted and rapid pressure relief can be facilitated when the battery cell 20 has thermal runaway.

[0185] In some embodiments, the inclination angle θ of the transition region 2136 relative to the fixed region 2135 can be equal to or between any of the following values: 40°, 45°, 50°, 55°, 60°, 65°, 70°, and 75°.

[0186] It should be understood that the pressure relief mechanism 213 of the embodiments of the present application can be fixed to the first wall 201 in various ways. For example, the pressure relief mechanism 213 can be fixed to the first wall 201 by welding, and covers the pressure relief hole 202.

[0187] In some embodiments, as shown in FIGS. 3-8, the pressure relief mechanism 213 can be fixed to the first wall 201 by means of a penetration weld, i.e., the connecting portion 2133 of the pressure relief mechanism 213 is arranged in a stacked manner with the first fixed region 203 of the first wall 201, and the two are fixedly connected by a same weld, i.e., are welded and fixed by means of a penetration weld.

[0188] For example, the first wall 201 is provided with a second groove 204 recessed towards the inside of the battery monomer 20, the pressure relief hole 202 is located at the bottom wall of the second groove 204, and the connecting portion 2133 is fixed with the area of the bottom wall of the second groove 204 surrounding the pressure relief hole 202. Further, the connecting portion 2133 is located on the side of the bottom wall of the second groove 204 away from the inside of the battery monomer 20, and in the thickness direction X of the first wall 201, it is convenient to achieve fixation between the connecting portion 2133 and the bottom wall of the second groove 204 by means of a penetration weld, and it is also convenient to achieve that the surface of the pressure relief mechanism 213 away from the inside of the battery monomer 20 does not exceed the surface of the first wall 201 away from the inside of the battery monomer 20.

[0189] In the embodiments of the present application, the fixation between the pressure relief mechanism 213 and the first wall 201 can also be achieved in other ways. FIG. 15 shows a partial exploded structural schematic view of a battery monomer 20 of another embodiment of the present application, for example, the FIG. 15 can be another possible exploded structural schematic view of the casing 211 of the battery monomer 20 shown in FIGS. 3 and 4; FIG. 16 shows a side view schematic view of a battery monomer 20 of another embodiment of the present application, for example, the FIG. 16 can be another possible side view schematic view of the battery monomer 20 shown in FIGS. 3-4; FIG. 17 shows a partial cross-sectional view schematic view of a battery monomer 20 of an embodiment of the present application, for example, the FIG. 17 can be a partial area of the cross-sectional view along the C-C' direction as shown in FIG. 11.

[0190] In some embodiments, as shown in FIGS. 15-17, the pressure relief mechanism 213 can also be fixed to the first wall 201 by means of a butt weld. For example, the connecting portion 2133 and the inner wall of the pressure relief hole 202 are fixed by means of a butt weld, which is simple to operate and facilitates improving processing efficiency.

[0191] It should be understood that, in the case that the pressure relief mechanism 213 is fixed to the inner wall of the pressure relief hole 202, the first wall 201 can be provided with the second groove 204 to achieve that the surface of the pressure relief mechanism 213 away from the inside of the battery monomer 20 does not exceed the surface of the first wall 201 away from the inside of the battery monomer 20; or, the first wall 201 can also not be provided with the second groove 204 to facilitate the processing of the first wall 201, and the pressure relief mechanism 213 can be fixed to the first wall 201 by reasonably setting the depth of the first groove 2134 to achieve that the surface of the pressure relief mechanism 213 away from the inside of the battery monomer 20 does not exceed the surface of the first wall 201 away from the inside of the battery monomer 20.

[0192] It should be understood that the connection part 2133 and the inner wall of the pressure relief hole 202 can also be indirectly fixed through other components. In some embodiments, the connection part 2133 and the inner wall of the pressure relief hole 202 are both fixed to other components, thereby achieving the relative fixation between the connection part 2133 and the inner wall of the pressure relief hole 202.

[0193] In the embodiments of the present application, as shown in FIGS. 15-17, the battery monomer 20 further comprises a support structure 215 fixed to the side of the first wall 201 facing the electrode assembly 22, and the pressure relief mechanism 213 is located on the side of the support structure 215 away from the electrode assembly 22, and the pressure relief mechanism 213 is welded to at least one of the support structure 215 and the first wall 201.

[0194] It should be understood that the support structure 215 is fixed to the side of the first wall 201 facing the electrode assembly 22, and the pressure relief mechanism 213 is located on the side of the support structure 215 away from the electrode assembly 22, i.e. the support structure 215 is located on the side of the first wall 201 and the pressure relief mechanism 213 facing the electrode assembly 22, which can save the external space of the battery monomer 20 occupied by the support structure 215, and facilitate the fixed connection between the pressure relief mechanism 213 and the first wall 201.

[0195] The pressure relief mechanism 213 of the embodiments of the present application is welded to at least one of the support structure 215 and the first wall 201. For example, the pressure relief mechanism 213 can be welded to the support structure 215, and the support structure 215 can be fixed to the first wall 201, thereby achieving the relative fixation between the pressure relief mechanism 213 and the first wall 201. For another example, the pressure relief mechanism 213 can be fixed to the first wall 201, and the first wall 201 can be fixed to the support structure 215, thereby achieving the relative fixation between the pressure relief mechanism 213, the first wall 201 and the support structure 215. For another example, the pressure relief mechanism 213 can be fixed to both the support structure 215 and the first wall 201, and the embodiments of the present application are not limited thereto.

[0196] On one hand, the support structure 215 can play a role in positioning during the fixed connection of the pressure relief mechanism 213 and the first wall 201, and can also be used to achieve the fixed connection between the pressure relief mechanism 213 and the first wall 201, which can effectively improve the processing efficiency of the battery monomer 20. On the other hand, the support structure 215 can also be used to support the pressure relief mechanism 213 and the first wall 201, increase the structural strength and stability between the first wall 201 and the pressure relief mechanism 213, especially during the use of the battery monomer 20, the battery monomer 20 will swell, and the support structure 215 can also be used to resist deformation, reduce the cracking between the pressure relief mechanism 213 and the first wall 201 caused by the swelling of the battery monomer 20, and improve the stability of the battery monomer 20.

[0197] The support structure 215 of the embodiment of the present application will be described below in conjunction with the drawings.

[0198] It should be understood that the support structure 215 and the first wall 201 are fixed by welding or adhesion, which is simple to operate, stable in structure, and easy to implement.

[0199] It should be understood that the materials of the pressure relief mechanism 213, the support structure 215 and the first wall 201 of the embodiment of the present application can be set according to actual application. In some embodiments, the materials of the pressure relief mechanism 213, the support structure 215 and the first wall 201 all include iron, copper or titanium. For example, the materials of the pressure relief mechanism 213, the support structure 215 and the first wall 201 are steel, copper alloy or titanium alloy, etc. On one hand, the pressure relief mechanism 213, the support structure 215 and the first wall 201 have the same material, which facilitates the mutual fixation of the three by welding; on the other hand, these materials can improve the structural strength of the pressure relief mechanism 213, the support structure 215 and the first wall 201, while reducing the thickness of the pressure relief mechanism 213, the support structure 215 and the first wall 201, thereby improving the energy density of the battery monomer 20. Moreover, since iron, copper or titanium has high strength, and the thickness of the pressure relief mechanism 213, the support structure 215 and the first wall 201 is relatively thin, it is difficult to obtain a stepped structure of the first wall 201 by stamping or other methods, so it is difficult to install the pressure relief mechanism 213 on the stepped structure of the first wall 201. During the process of fixing the pressure relief mechanism 213 and the first wall 201 by seam welding or penetration welding, the welding area of the pressure relief mechanism 213 and the first wall 201 is supported by the support structure 215, which can reduce the phenomenon of laser leakage caused by the gap between the pressure relief mechanism 213 and the first wall 201 during welding, and improve the welding strength.

[0200] It should be understood that the surface of the pressure relief mechanism 213 facing the electrode assembly 22 does not exceed the surface of the support structure 215 facing the electrode assembly 22. No matter whether the body part 2131 of the pressure relief mechanism 213 protrudes towards the inside or outside of the battery monomer 20, the surface of the pressure relief mechanism 213 facing the electrode assembly 22 does not exceed the surface of the support structure 215 facing the electrode assembly, so as to protect the pressure relief mechanism 213.

[0201] In some embodiments, the thickness T3 of the support structure 215 is in the range of [0.4mm, 1.5mm]. The thickness T3 of the support structure 215 is greater than or equal to 0.4mm, which can increase the structural strength and stability of the support structure 215; and the thickness T3 of the support structure 215 is less than or equal to 1.5mm, which can reduce the overall volume of the support structure 215, thereby reducing the internal space of the battery monomer 20 occupied by the support structure 215 and improving the energy density of the battery monomer 20.

[0202] In some embodiments, the thickness T3 of the support structure 215 can also be in the range of [0.4mm, 1mm] or [0.4mm, 0.8mm]; or the thickness T3 of the support structure 215 can be any of the following values or between any two of the following values: 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm and 1.5mm.

[0203] In the embodiments of the present application, the thickness T3 of the support structure 215 is generally greater than or equal to the thickness of the connecting part 2133. In order to enable the pressure relief mechanism 213 to actuate in time when the battery monomer 20 is in thermal runaway, the thickness T2 of the pressure relief mechanism 213 is generally small, and the thickness of the connecting part 2133 is also small. Therefore, the thickness T3 of the support structure 215 is greater than or equal to the thickness of the connecting part 2133, which can improve the structural strength of the support structure 215 and reduce the deformation of the pressure relief mechanism 213 at the connecting part 2133, thereby improving the structural stability of the pressure relief mechanism 213.

[0204] The measurement direction of the thickness T3 of the support structure 215 of the embodiments of the present application is consistent with the measurement direction of the thickness of the connecting part 2133 of the pressure relief mechanism 213. For example, as shown in FIGS. 15-17, the thickness T3 of the support structure 215 and the thickness of the connecting part 2133 can be measured along the thickness direction X of the first wall 201.

[0205] The thickness T3 of the support structure 215 can be an average thickness of the support structure 215 as a whole. For example, if the support structure 215 is a relatively flat structure as a whole, the thicknesses of different regions of the support structure 215 are relatively small, and thus the average thickness of the support structure 215 as a whole can be measured as the thickness T3 of the support structure 215. For another example, the thickness T3 of the support structure 215 can also be an average thickness of a local region of the support structure 215 close to the connecting portion 2133. In particular, if the thicknesses of different regions of the support structure 215 are relatively large, the average thickness of a portion of the support structure 215 close to the connecting portion 2133 can be measured as the thickness T3 of the support structure 215.

[0206] It should be understood that the relative positions among the support structure 215, the pressure relief mechanism 213, and the first wall 201 of the battery cell 20 can be set according to actual applications. In some embodiments, the surface of the first fixed region 203 of the first wall 201 facing the support structure 215 is flush with the surface of the connecting portion 2133 facing the support structure 215, so that the first fixed region 203 and the connecting portion 2133 are both fixed on the same surface of the support structure 215. In this way, the total thickness of the support structure 215, the first fixed region 203, and the connecting portion 2133 in the thickness direction X of the support structure 215 can be reduced, so as to improve the energy density of the battery cell 20. In addition, by setting the surface of the first fixed region 203 facing the support structure 215 to be flush with the surface of the connecting portion 2133 facing the support structure 215, when the first fixed region 203 is attached to the surface of the support structure 215, the connecting portion 2133 can also be attached to the surface of the support structure 215, so as to reduce the gap between the first fixed region 203 and the support structure 215 or the gap between the connecting portion 2133 and the support structure 215, and improve the structural stability and sealing performance of the battery cell 20.

[0207] It should be understood that, as shown in FIGS. 15 to 17, when the surface of the first fixed region 203 facing the support structure 215 is flush with the surface of the connecting portion 2133 facing the support structure 215, the first fixed region 203, the connecting portion 2133, and the support structure 215 can be fixed in various ways. For example, FIG. 18 shows another partial cross-sectional view of the battery cell 20 according to an embodiment of the present application. For example, FIG. 18 can be used to show one way of fixing the first fixed region 203, the connecting portion 2133, and the support structure 215, i.e., FIG. 18 can be one possible way of fixing the first fixed region 203, the connecting portion 2133, and the support structure 215 shown in FIG. 17.

[0208] In some embodiments, the pressure relief mechanism 213, the inner wall of the pressure relief hole 202 and the support structure 215 are connected by the same weld seam, which is located on the side of the support structure 215 away from the electrode assembly 22. Specifically, as shown in FIG. 18, the connecting portion 2133 and the inner wall of the pressure relief hole 202 can be fixed by means of a butt weld, and a weld seam D is formed at the same time, and the support structure 215 is also welded and fixed to the side of the weld seam D facing the inside of the battery monomer 20. The first fixed area 203 includes the inner wall of the pressure relief hole 202, and the side surface of the connecting portion 2133 facing the inner wall of the pressure relief hole 202 is attached to the inner wall of the pressure relief hole 202, and the support structure 215 is located on the side of the connecting portion 2133 and the first fixed area 203 facing the inside of the battery monomer 20. When welding, the first fixed area 203 and the connecting portion 2133 are connected by means of a butt weld, and the support structure 215, the first fixed area 203 and the connecting portion 2133 are welded and fixed at the same time, and the weld seam D formed by welding includes the area between the connecting portion 2133 and the inner wall of the pressure relief hole 202, and the area of the support structure 215 close to the weld seam. In this way, the support structure 215, the first fixed area 203 and the connecting portion 2133 can be welded and fixed at the same time, which is high in welding efficiency, thereby improving the processing efficiency of the battery monomer 20; and the connecting portion 2133 is directly welded to the inner wall of the pressure relief hole 202, which can minimize the gap between the connecting portion 2133 of the pressure relief mechanism 213 and the inner wall of the pressure relief hole 202, and improve the sealing performance and reliability of the battery monomer 20.

[0209] In some embodiments, the first fixed area 203, the connecting portion 2133 and the support structure 215 are made of the same material, so as to be connected and fixed by means of the butt weld described above. For example, the first fixed area 203, the connecting portion 2133 and the support structure 215 are all made of steel; or the first fixed area 203, the connecting portion 2133 and the support structure 215 are all made of copper. On the one hand, the first fixed area 203, the connecting portion 2133 and the support structure 215 have the same material, which is convenient for welding; on the other hand, the first fixed area 203, the connecting portion 2133 and the support structure 215 can be made of steel or copper to improve the structural strength and reduce the thickness of the first fixed area 203, the connecting portion 2133 and the support structure 215, thereby improving the energy density of the battery monomer 20.

[0210] FIG. 19 shows another partial cross-sectional view of the battery monomer 20 according to an embodiment of the present application. For example, FIG. 19 can be used to show another way of fixing the pressure relief mechanism 213, the first wall 201 and the support structure 215, i.e. FIG. 19 can be another possible way of fixing the pressure relief mechanism 213, the first wall 201 and the support structure 215 shown in FIG. 17.

[0211] As shown in FIG. 19, the pressure relief mechanism 213 and the support structure 215 are connected by the same weld, and the first wall 201 and the support structure 215 are connected by the same weld. The weld between the pressure relief mechanism 213 and the support structure 215 is different from the weld between the first wall 201 and the support structure 215. Specifically, as shown in FIG. 19, the first fixed area 203 is located on the surface of the support structure 215 away from the inside of the battery monomer 20, and the two are fixed by penetrating welding to form the same weld E1. At the same time, the connecting part 2133 is also located on the surface of the support structure 215 away from the inside of the battery monomer 20, and the two are fixed by penetrating welding to form the same weld E2, and the weld E1 and the weld E2 are different welds. In this way, the relative fixation between the first fixed area 203 and the connecting part 2133 can be realized through the support structure 215, that is, the relative fixation between the pressure relief mechanism 213 and the first wall 201 is realized, and the fixation mode is more flexible.

[0212] In some embodiments, considering that the first fixed area 203 and the support structure 215 are connected by the same weld, in order to facilitate welding, the area of the first fixed area 203 and the support structure 215 used for welding with the first fixed area 203 generally includes the same material. Similarly, the connecting part 2133 and the support structure 215 are connected by the same weld, so the area of the connecting part 2133 and the support structure 215 used for welding with the connecting part 2133 generally includes the same material.

[0213] In some embodiments, the material of the first fixed area 203 includes steel, the material of the connecting part 2133 includes aluminum, the material of the support structure 215 close to the first fixed area 203 includes steel, and the material of the support structure 215 close to the connecting part 2133 includes aluminum. On the one hand, the material of the support structure 215 close to the first fixed area 203 is the same as the material of the first fixed area 203, and the material of the support structure 215 close to the connecting part 2133 is the same as the material of the connecting part 2133, which facilitates welding. On the other hand, the material of the first fixed area 203 of the first wall 201 includes steel, which can improve the structural strength and stability of the first wall 201, and the material of the connecting part 2133 of the pressure relief mechanism 213 includes aluminum, which facilitates the molding of the pressure relief mechanism 213 and improves the processing efficiency of the battery monomer 20.

[0214] In some embodiments, as shown in FIG. 19, the connecting part 2133 abuts the inner wall of the pressure relief hole 202 to minimize the gap between the connecting part 2133 of the pressure relief mechanism 213 and the inner wall of the pressure relief hole 202, thereby improving the sealing and reliability of the battery monomer 20.

[0215] In some embodiments, the surface of the first fixed region 203 away from the interior of the battery cell is flush with the surface of the connecting portion 2133 away from the interior of the battery cell, so as to reduce the height difference between the two, thereby reducing the influence of other components outside the battery cell 20 on the first fixed region 203 and the connecting portion 2133. For example, as shown in FIGS. 18 and 19, by setting the thickness of the first fixed region 203 equal to the thickness of the connecting portion 2133, the surface of the first fixed region 203 facing the interior of the battery cell 20 can be flush with the surface of the connecting portion 2133 facing the interior of the battery cell 20, and the surface of the first fixed region 203 away from the interior of the battery cell 20 can be flush with the surface of the connecting portion 2133 away from the interior of the battery cell 20.

[0216] It should be understood that the first fixed region 203, the connecting portion 2133, and the support structure 215 of the embodiments of the present application can also have other relative positional relationships. FIG. 20 shows a partial cross-sectional view of a battery cell 20 of another embodiment of the present application, for example, which can be a partial region of another possible cross-sectional view along the A-A' direction as shown in FIG. 6.

[0217] In some embodiments, the pressure relief mechanism 213, the support structure 215, and the first wall 201 are arranged in a stacked manner along the thickness direction of the first wall 201, and are connected by the same weld. Specifically, as shown in FIG. 20, the first fixed region 203, the connecting portion 2133, and the support structure 215 can be fixed by means of a through-weld, that is, along the thickness direction X of the first wall 201, part of the first fixed region 203, part of the connecting portion 2133, and part of the support structure 215 pass through the through-weld to form the same weld F, which not only facilitates processing, but also can improve the structural strength and reliability of the battery cell 20.

[0218] It should be understood that the arrangement order of the first fixed region 203, the connecting portion 2133, and the support structure 215 can be set according to actual application. For example, the support structure 215 is usually located on the side of the first fixed region 203 and the connecting portion 2133 facing the interior of the battery cell 20; for another example, the first fixed region 203 can be located between the connecting portion 2133 and the support structure 215; for another example, the connecting portion 2133 can be located between the first fixed region 203 and the support structure 215, and the embodiments of the present application are not limited thereto.

[0219] In some embodiments, the first fixed region 203, the connecting portion 2133, and the support structure 215 are made of the same material, so as to be connected and fixed by the above-mentioned penetrating welding. For example, the first fixed region 203, the connecting portion 2133, and the support structure 215 are all made of steel; or, the first fixed region 203, the connecting portion 2133, and the support structure 215 are all made of copper. On the one hand, the first fixed region 203, the connecting portion 2133, and the support structure 215 have the same material, which facilitates welding; on the other hand, the first fixed region 203, the connecting portion 2133, and the support structure 215 can be made of steel or copper to improve the structural strength of the first fixed region 203, the connecting portion 2133, and the support structure 215, and reduce the thickness of the first fixed region 203, the connecting portion 2133, and the support structure 215, thereby improving the energy density of the battery monomer 20.

[0220] It should be understood that, in the above-mentioned embodiments in the present application, as shown in FIGS. 18-20, there is at least one welding seam between the pressure relief mechanism 213, the support structure 215, and the first wall 201, and the orthogonal projection of the at least one welding seam towards the outer surface of the support structure 215 along the thickness direction of the first wall 201 is located in the middle region of the outer surface of the support structure 215, which is the surface of the support structure 215 away from the electrode assembly 22, so that the outer surface of the support structure 215 can cover the at least one welding seam between the pressure relief mechanism 213, the support structure 215, and the first wall 201, and the at least one welding seam does not exceed the outer surface of the support structure 215, thereby increasing the stability of the support structure 215 and improving the stability of the battery monomer 20.

[0221] In some embodiments, the orthogonal projection of the at least one welding seam towards the outer surface of the support structure 215 along the thickness direction X of the first wall 201 is symmetrically distributed with respect to the center line of the outer surface of the support structure 215, so that the at least one welding seam is more evenly distributed on the surface of the support structure 215, reducing the risk of the welding seam deviating from the outer surface of the support structure 215, and improving the structural stability and reliability. For example, as shown in FIGS. 18 and 20, in the case where there is one welding seam between the pressure relief mechanism 213, the support structure 215, and the first wall 201, the welding seam can be distributed along the center line of the outer surface of the support structure 215, or close to the center line of the outer surface of the support structure 215; as shown in FIG. 19, in the case where there are multiple welding seams, for example, two welding seams, between the pressure relief mechanism 213, the support structure 215, and the first wall 201, the multiple welding seams are symmetrically distributed with respect to the center line of the outer surface of the support structure 215, or approximately symmetrically distributed, i.e., allowing a small range of deviation between the multiple welding seams.

[0222] In some embodiments, the side of the welding seam facing the electrode assembly 22 does not exceed the surface of the support structure 215 facing the electrode assembly 22, i.e., the support structure 215 is not welded through during the welding process, to prevent the welding from damaging other components inside the battery monomer 20, improve the welding efficiency and welding effect, and thus improve the processing qualification rate and structural stability of the battery monomer 20.

[0223] It should be understood that the shape of the support structure 215 of the embodiments of the present application can be set according to actual application. For example, the support structure 215 is annular, and the inner ring of the support structure 215 corresponds to the pressure relief hole 202. The pressure relief mechanism 213 is used to cover the pressure relief hole 202, and therefore, the connecting portion 2133 of the pressure relief mechanism 213 and the first fixed region 203 of the first wall 201 are generally close to the pressure relief hole 202. The support structure 215 is annular, and the inner ring corresponds to the pressure relief hole 202, which not only facilitates the relative fixation of the support structure 215, the first fixed region 203, and the connecting portion 2133, but also reduces the influence of the support structure 215 on the pressure relief hole 202. When the battery monomer 20 is in thermal runaway, the pressure relief mechanism 213 can be damaged in time through the pressure relief hole 202, so that the pressure relief mechanism 213 is actuated in time, and the reliability of the battery monomer 20 is improved.

[0224] In some embodiments, the support structure 215 can be a circular ring structure or a square ring structure, or the support structure 215 can also be other annular structures. For example, in the embodiments of the present application, the pressure relief hole 202 is taken as a waist circle, and the corresponding support structure 215 can also be a waist circle annular structure, and the embodiments of the present application are not limited thereto.

[0225] In some embodiments, the surface of the support structure 215 facing the first fixed region 203 and the connecting portion 2133 is a plane before welding. Considering that the surface of the first fixed region 203 facing the support structure 215 and the surface of the connecting portion 2133 facing the support structure 215 are generally planes, and the surface of the support structure 215 facing the first fixed region 203 and the connecting portion 2133 is used to fit with the surface of the first fixed region 203 and / or the surface of the connecting portion 2133, therefore, the surface of the support structure 215 is set as a plane, which facilitates the close fitting of the support structure 215 with the surface of the first fixed region 203 and / or the surface of the connecting portion 2133, reduces the gap, and thus improves the welding effect and the structural strength after welding of the support structure 215, the first fixed region 203, and the connecting portion 2133, and reduces the welding burst points caused by the excessive gap between the support structure 215 and the first fixed region 203, or the welding burst points caused by the excessive gap between the support structure 215 and the connecting portion 2133.

[0226] In the embodiments of the present application, the battery cell 20 further comprises a protection sheet 217 located on the side of the pressure relief mechanism 213 away from the electrode assembly 22 to protect the pressure relief mechanism 213, reduce damage of the pressure relief mechanism 213 by external components of the battery cell 20, and improve the service life of the pressure relief mechanism 213.

[0227] FIGS. 21 and 22 respectively show another two possible partial cross-sectional schematic views of the battery cell 20 of the embodiments of the present application, for example, both of the FIGS. 21 and 22 take the welding manner as shown in FIG. 18 as an example, and respectively show possible structures of the protection sheet 217 of the embodiments of the present application, but the relevant description is also applicable to other embodiments of the present application, and for the sake of brevity, will not be repeated here.

[0228] In some embodiments, as shown in FIG. 21, a stepped structure 2137 is arranged on the side of the connecting portion 2133 away from the electrode assembly 22, the protection sheet 217 is fixed to the bottom wall of the stepped structure 2137, and the side of the body portion 2131 away from the electrode assembly 22 does not exceed the bottom wall of the stepped structure 2137. By arranging the stepped structure 2137 to accommodate at least part of the protection sheet 217, the height of the surface of the protection sheet 217 facing the outside of the battery cell 20 beyond the surface of the first wall 201 can be reduced, for example, the depth of the stepped structure 2137 can be arranged such that the surface of the protection sheet 217 facing the outside of the battery cell 20 does not exceed the surface of the first wall 201 facing the outside of the battery cell 20, so that the outer surface of the battery cell 20 is relatively smooth, the local protrusion is reduced, the arrangement of multiple battery cells 20 in the battery device 10 is facilitated, the mutual influence of the multiple battery cells 20 is reduced, the internal space utilization of the battery device 10 is improved, and the energy density of the battery device 10 is further improved.

[0229] In some embodiments, as shown in FIG. 22, the protection sheet 217 is fixed to the side of the first wall 201 away from the electrode assembly 22, and the protection sheet 217 covers the weld between the pressure relief mechanism 213 and the first wall 201. By covering the pressure relief mechanism 213 with the protection sheet 217, the pressure relief mechanism 213 can be protected. Further, the protection sheet 217 can also be used to cover the weld between the pressure relief mechanism 213 and the first wall 201 to protect the weld and improve the stability and reliability of the weld between the pressure relief mechanism 213 and the first wall 201. For example, there can be at least one weld between the pressure relief mechanism 213 and the first wall 201, and the protection sheet 217 can be used to cover all of the at least one weld to protect the at least one weld, but the embodiments of the present application are not limited thereto.

[0230] FIG. 23 shows another partial cross-sectional view of the battery cell 20 according to an embodiment of the application. For example, FIG. 23 can be a partial region of the cross-sectional view along the direction of G-G' shown in FIG. 16, which can be the region G shown in FIG. 16.

[0231] As shown in FIG. 23, the battery cell 20 according to an embodiment of the application further includes a protection member 216 fixed to the side of the first wall 201 facing the electrode assembly 22, the surfaces of the support structure 215 and the pressure relief mechanism 213 facing the electrode assembly 22 protrude from the surface of the first wall 201 facing the electrode assembly 22, and the surface 2161 of the protection member 216 facing the electrode assembly 22 protrudes from the surfaces of the support structure 215 and the pressure relief mechanism 213 facing the electrode assembly 22.

[0232] In the embodiment of the application, the surfaces of the support structure 215 and the pressure relief mechanism 213 facing the inside of the battery cell 20 protrude from the surface of the first wall 201 facing the inside of the battery cell 20, so as to reduce the part of the side of the pressure relief mechanism 213 facing the outside of the battery cell 20 protruding from the first wall 201, reduce the external space occupied by the pressure relief mechanism 213, and further reduce the mutual influence between the pressure relief mechanism 213 and other components outside. It should be understood that the support structure 215 and the pressure relief mechanism 213 according to an embodiment of the application can only exist in some regions to meet the condition that the surfaces facing the battery cell 20 protrude from the first wall 201, so as to flexibly set the structure and position of the pressure relief mechanism 213 and the support structure 215.

[0233] Further, the side of the first wall 201 facing the inside of the battery cell 20 is provided with the protection member 216, the surface 2161 of the protection member 216 facing the inside of the battery cell 20 protrudes from the surfaces of the support structure 215 and the pressure relief mechanism 213 facing the inside of the battery cell 20, i.e., along the thickness direction X of the first wall 201, and at least part of the surface 2161 of the protection member 216 facing the inside of the battery cell 20 can protrude from the surfaces of the support structure 215 and the pressure relief mechanism 213 facing the inside of the battery cell 20 from the outside to the inside of the battery cell 20. In this way, the influence of the components inside the battery cell 20 on the support structure 215 and the pressure relief mechanism 213 can be reduced, and the reliability of the pressure relief mechanism 213 and the battery cell 20 can be improved.

[0234] In some embodiments, as shown in FIGS. 3-7 and 15-23, the first wall 201 is a side wall of the shell 211 adjacent to the opening 2111, i.e., the pressure relief mechanism 213 is arranged at the first wall 201. In one aspect, since the area of the cover plate 212 is limited, arranging the pressure relief mechanism 213 at the shell 211 can save the space of the cover plate 212 and facilitate the processing. In another aspect, when the electrode assembly 22 enters the shell 211 from the opening 2111 of the shell 211, since the surface 2161 of the protection member 216 facing the inside of the battery monomer 20 protrudes from the surface of the support structure 215 and the surface of the pressure relief mechanism 213 facing the inside of the battery monomer 20, the electrode assembly 22 can enter the shell 211 along the surface 2161 of the protection member 216 facing the inside of the battery monomer 20, reducing the interference of the electrode assembly 22 with the pressure relief mechanism 213 and the support structure 215 during the assembly process, protecting the pressure relief mechanism 213 and the support structure 215, thereby improving the processing yield of the battery monomer 20, and also improving the reliability and service life of the pressure relief mechanism 213 and the battery monomer 20.

[0235] In some embodiments, an end of the protection member 216 facing the opening 2111 is provided with a chamfer 2165 at the intersection with the surface 2161 of the protection member 216 facing the inside of the battery monomer 20, so as to facilitate the entry of the internal electrode assembly 22, reduce the obstruction of the protection member 216 to the electrode assembly 22, and improve the installation efficiency.

[0236] It should be understood that the shape of the chamfer 2165 of the embodiments of the present application can be set according to actual application. FIGS. 24 and 25 respectively show partial cross-sectional schematic views of the protection member 216 of the embodiments of the present application, for example, FIGS. 24 and 25 can be other possible implementations of the area of the protection member 216 close to the chamfer 2165 in the cross-sectional view shown in FIG. 23, and the cross-sections shown in FIGS. 24 and 25 can be the partial cross-sectional schematic view in the G-G’ direction shown in FIG. 16.

[0237] In some embodiments, as shown in FIG. 23, the chamfer 2165 can be an inclined plane, i.e., the intersection of the surface 2161 of the protection member 216 facing the inside of the battery monomer 20 and the end of the protection member 216 facing the opening 2111 is provided with an inclined plane as the chamfer 2165.

[0238] In some embodiments, as shown in FIG. 24, the chamfer 2165 can also be a rounded corner, i.e., the intersection of the surface 2161 of the protection member 216 facing the inside of the battery monomer 20 and the end of the protection member 216 facing the opening 2111 is connected with a rounded corner to form the chamfer 2165.

[0239] In some embodiments, considering that the thickness of the protection piece 216 is generally thin, the chamfer 2165 can occupy at least part of the area of the end of the protection piece 216 facing the opening 2111. For example, as shown in FIGS. 23 and 24, the partial area of the end of the protection piece 216 facing the opening 2111 is used to form the chamfer 2165; or as shown in FIG. 25, the entire area of the end of the protection piece 216 facing the opening 2111 can be used to form the chamfer 2165, so that the area where the chamfer 2165 is located is larger, facilitating the electrode assembly 22 to enter the inside of the shell 211, thereby improving the installation efficiency, but the embodiments of the present application are not limited thereto.

[0240] In some embodiments, the surfaces 2161 of the protection piece 216 facing the inside of the battery monomer 20 are flush with each other, i.e., the surfaces 2161 of the protection piece 216 facing the inside of the battery monomer 20 are relatively flat, so that the electrode assembly 22 can quickly enter the inside of the shell 211 along the surfaces 2161, which can not only reduce the damage to the electrode assembly 22, but also speed up the processing and assembly efficiency of the battery monomer 20.

[0241] In some embodiments, the protection piece 216 is located around the support structure 215 and the pressure relief mechanism 213, rather than only in the middle region of the support structure 215 and the pressure relief mechanism 213, which can reduce the processing and installation difficulty of the protection piece 216 on the one hand; on the other hand, considering that during the assembly process of the internal components of the battery monomer 20, such as the assembly process of the electrode assembly 22, the process of entering the inside of the battery monomer 20 from the opening 2111 of the shell 211 will first pass through the periphery of the pressure relief mechanism 213 and / or the support structure 215, and the protection piece 216 is arranged around the pressure relief mechanism 213, which can better protect the pressure relief mechanism 213 and / or the support structure 215.

[0242] It should be understood that the arrangement of the protection piece 216 around the pressure relief mechanism 213 can include that the protection piece 216 is arranged around the periphery of the pressure relief mechanism 213, or the protection piece 216 can be arranged around the periphery of the partial region of the pressure relief mechanism 213.

[0243] It should be understood that the protection piece 216 of the embodiments of the present application can be implemented in various ways. For example, the protection piece 216 of the embodiments of the present application can be an integral structure, or the protection piece 216 can include multiple separately arranged parts to be flexibly applicable to multiple application scenarios. FIG. 26 shows a possible side view structural schematic diagram of the protection piece 216 of the embodiments of the present application, for example, which can be a side view of the protection piece 216 included in the battery monomer 20 shown in FIGS. 15 to 19.

[0244] In some embodiments, as shown in FIG. 26, the protection member 216 includes a first part 2163 and a second part 2164 arranged in a spaced manner, and the pressure relief mechanism 213 and the support structure 215 are located between the first part 2163 and the second part 2164. Arranging the protection member 216 to include the first part 2163 and the second part 2164 arranged in a spaced manner can reduce the processing difficulty of the protection member 216. In particular, in the case where the area of the first wall 201 is limited, there can be a part of the area around the pressure relief mechanism 213 that is too small in size, for example, the size in the width direction Y of the first wall 201 can be small. In this part of the area, the protection member 216 is not arranged, which can reduce the processing difficulty of the protection member 216. In addition, the pressure relief mechanism 213 is located between the first part 2163 and the second part 2164, which can still effectively protect the pressure relief mechanism 213.

[0245] Further, the first part 2163 and the second part 2164 are distributed in the direction Z perpendicular to the end face of the opening 2111, i.e., in the direction in which the electrode assembly 22 enters the shell 211, so that during the assembly of the electrode assembly 22, the electrode assembly 22 is in contact with the protection member 216, for example, the first part 2163, in advance of the area corresponding to the pressure relief mechanism 213, so as to protect the pressure relief mechanism 213 as much as possible.

[0246] In some embodiments, the protection member 216 can also include more than two split structures arranged in a spaced manner around the pressure relief mechanism 213 to protect the pressure relief mechanism 213. In this way, the protection member 216 is arranged more flexibly.

[0247] In some embodiments, the protection member 216 can also be a one-piece structure. FIG. 27 shows another possible side view structural schematic diagram of the protection member 216 according to an embodiment of the application. For example, the protection member 216 shown in FIG. 27 can be another structure different from the protection member 216 included in the battery monomer 20 shown in FIGS. 15 to 19. As shown in FIG. 27, the protection member 216 is provided with a relief opening 2162 for avoiding the pressure relief mechanism 213 and the support structure 215. The processing is simple, and the pressure relief mechanism 213 can be avoided through the relief opening 2162, which reduces the obstruction to the pressure relief mechanism 213, so that the pressure relief mechanism 213 can be actuated in time when the battery monomer 20 is in thermal runaway.

[0248] In some embodiments, as shown in FIG. 27, the integrated protective member 216 can also be provided in other structures, for example, the protective member 216 is provided with a groove 2166 with an opening facing the pressure relief mechanism 213, the groove 2166 is used to accommodate the pressure relief mechanism 213 and the support structure 215, the bottom of the groove 2166 is provided with a thinned area 2167 corresponding to the pressure relief mechanism 213, the thickness of the thinned area 2167 is smaller than the thickness of other areas of the bottom of the groove 2166. In one aspect, the internal space of the groove 2166 can be used to avoid the pressure relief mechanism 213 and the support structure 215, and the thinned area 2167 provided at the bottom wall of the groove 2166 can be used to be damaged in time when the battery cell 20 occurs thermal runaway, so as to reduce the influence of the bottom wall of the groove 2166 on the pressure relief mechanism 213, so that the pressure relief mechanism 213 can be damaged in time, and the pressure inside the battery cell 20 can be released in time. In addition, the surface of the protective member 216 facing the inside of the battery cell 20 is a continuous plane, and there is no discontinuous area, so that the electrode assembly 22 can enter the shell 211 more continuously and smoothly, and the installation efficiency is improved.

[0249] FIGS. 28 and 29 respectively show cross-sectional views of the protective member 216 of the embodiments of the present application, for example, the cross-sections shown in FIGS. 28 and 29 are perpendicular to the thickness direction Y of the battery cell 20, and the cross-sections shown in FIGS. 28 and 29 can be the possible structures of the protective member 216 in the cross-sectional view along the G-G’ direction shown in FIG. 16. As shown in FIG. 28, the thinned area 2167 of the bottom wall of the groove 2166 can be a groove structure, and the area of the thinned area 2167 covers at least the weak part 2132 of the pressure relief mechanism 213, so as to reduce the influence on the actuation of the pressure relief mechanism 213.

[0250] In some embodiments, as shown in FIG. 29, the thinned area 2167 of the bottom wall of the groove 2166 can also be an annular structure, so that the thinned area 2167 corresponds to the annular weak part 2132 of the pressure relief mechanism 213, so as to reduce the influence on the actuation of the pressure relief mechanism 213.

[0251] It should be understood that the size of the protector 216 of the embodiments of the present application can be set according to actual application. For example, in the case that the protector 216 is provided with the avoiding opening 2162 or the groove 2166, the size of the avoiding opening 2162 or the groove 2166 in each direction is generally greater than or equal to the size of the pressure relief mechanism 213, so as to reduce the obstruction of the avoiding opening 2162 or the groove 2166 to the pressure relief mechanism 213, and to enable the pressure relief mechanism 213 to actuate in time when the battery monomer 20 is in thermal runaway. For another example, in each direction parallel to the first wall 201, the size of the protector 216 is generally less than or equal to the size of the first wall 201, so as to reduce the influence of the protector 216 on the bending area of the shell 211, and also to reduce the influence on the connection between the shell 211 and the cover plate 212, and to improve the reliability of the shell 211. For another example, in the direction Z perpendicular to the end surface of the opening 2111 of the shell 211, the size of the protector 216 is generally close to the size of the first wall 201, so as to maximize the protection of the electrode assembly 22 from entering the shell 211.

[0252] It should be understood that the material of the protector 216 of the embodiments of the present application can be set according to actual application. For example, the protector 216 is generally an insulating material. For another example, the material of the protector 216 includes plastic, so as to reduce the cost and facilitate processing.

[0253] It should be understood that the fixing mode of the protector 216 of the embodiments of the present application can be set according to actual application. For example, the protector 216 is fixed to the first wall 201 by an adhesive, which is simple to operate and easy to implement, and has stable structure, and reduces the risk of mutual dislocation between the protector 216 and the first wall 201, or even the falling of the protector 216.

[0254] According to some embodiments of the present application, the present application further provides a battery device 10, which includes the battery monomer 20 of any one of the above schemes.

[0255] According to some embodiments of the present application, the present application further provides a power consumption device, which includes the battery device 10 of any one of the above schemes, and the battery device 10 is used to provide electric energy for the power consumption device.

[0256] The power consumption device can be the device or system of any one of the above application batteries.

[0257] According to some embodiments of the present application, referring to the drawings, the present application provides a battery cell 20, comprising: a shell 211, the shell 211 having a first wall 201 provided with a pressure relief hole 202; an electrode assembly 22, the electrode assembly 22 being contained in the shell 211; a pressure relief mechanism 213, the pressure relief mechanism 213 covering the pressure relief hole 202, the base material of the pressure relief mechanism 213 being iron; wherein the pressure relief mechanism 213 comprises a weak portion 2132, a body portion 2131 and a connecting portion 2133, the weak portion 2132 being configured to be destroyed to release pressure when the pressure inside the shell 211 reaches a threshold value, the body portion 2131 being located in the area surrounded by the weak portion 2132, and the connecting portion 2133 being located outside the weak portion 2132 and being used to connect the first wall 201; the body portion 2131 is a protruding structure that protrudes towards the direction close to the electrode assembly 22 or away from the electrode assembly 22.

[0258] The material of the pressure relief mechanism 213 comprises: stainless steel and / or carbon steel. The base material of the shell 211 is iron. The electrode assembly 22 comprises at least two layers of electrode sheets; the at least two layers of electrode sheets are arranged in a stacked manner, and the stacking direction of the at least two layers of electrode sheets is a first direction; or the at least two layers of electrode sheets are arranged in a wound manner, and the at least two layers of electrode sheets each comprise a flat section located in the middle of the electrode assembly 22 and a curved section located at both ends of the electrode assembly 22, and the stacking direction of the at least two layers of electrode sheets at the flat section is the first direction; the cross section of the body portion 2131 in at least one plane perpendicular to the first direction is arc-shaped.

[0259] The connecting portion 2133 comprises a fixed area 2135 and a transition area 2136, the fixed area 2135 being used to connect with the first wall 201, and the transition area 2136 being used to connect the fixed area 2135 with the weak portion 2132, the fixed area 2135 being arranged in parallel with respect to the first wall 201, the transition area 2136 being flush with the fixed area 2135, or the transition area 2136 protruding towards the direction close to the electrode assembly 22 with respect to the fixed area 2135; the body portion 2131 protrudes towards the direction close to the electrode assembly 22 with respect to the fixed area 2135.

[0260] The connecting portion 2133 comprises a fixed area 2135 and a transition area 2136, the fixed area 2135 being used to connect with the first wall 201, and the transition area 2136 being used to connect the fixed area 2135 with the weak portion 2132, the fixed area 2135 being arranged in parallel with respect to the first wall 201, the transition area 2136 being flush with the fixed area 2135, or the transition area 2136 protruding towards the direction close to the electrode assembly 22 with respect to the fixed area 2135; the body portion 2131 protrudes towards the direction close to the electrode assembly 22 with respect to the fixed area 2135.

[0261] The battery cell further comprises a support structure 215 fixed to a side of the first wall 201 facing the electrode assembly 22, the pressure relief mechanism 213 is located on a side of the support structure 215 facing away from the electrode assembly 22, and the pressure relief mechanism 213 is welded to at least one of the support structure 215 and the first wall 201. The support structure 215 and the first wall 201 are fixed by welding or by adhesion. The materials of the pressure relief mechanism 213, the support structure 215, and the first wall 201 all comprise steel. The surface of the pressure relief mechanism 213 facing the electrode assembly 22 does not exceed the surface of the support structure 215 facing the electrode assembly 22.

[0262] The battery cell further comprises a protection member 216 fixed to a side of the first wall 201 facing the electrode assembly 22, the surfaces of the support structure 215 and the pressure relief mechanism 213 facing the electrode assembly 22 all protrude from the surface of the first wall 201 facing the electrode assembly 22, and the surface 2161 of the protection member 216 facing the electrode assembly 22 protrudes from the surfaces of the support structure 215 and the pressure relief mechanism 213 facing the electrode assembly 22.

[0263] The protection member 216 comprises a first portion 2163 and a second portion 2164 arranged in a spaced manner, and the pressure relief mechanism 213 and the support structure 215 are located between the first portion 2163 and the second portion 2164. Alternatively, the protection member 216 is provided with a relief opening 2162 for avoiding the pressure relief mechanism 213 and the support structure 215. Alternatively, the protection member 216 is provided with a groove 2166 facing the pressure relief mechanism 213, the groove 2166 is used for accommodating the pressure relief mechanism 213 and the support structure 215, the bottom of the groove 2166 is provided with a thinned area 2167 corresponding to the pressure relief mechanism 213, and the thickness of the thinned area 2167 is less than the thickness of other areas of the bottom of the groove 2166.

[0264] The pressure relief mechanism 213, the inner wall of the pressure relief hole 202, and the support structure 215 are connected by the same welding seam located on a side of the support structure 215 away from the electrode assembly 22. Alternatively, the pressure relief mechanism 213 and the support structure 215 are connected by the same welding seam, the first wall 201 and the support structure 215 are connected by the same welding seam, and the welding seam between the pressure relief mechanism 213 and the support structure 215 is different from the welding seam between the first wall 201 and the support structure 215. Alternatively, the pressure relief mechanism 213, the support structure 215, and the first wall 201 are arranged in a stacked manner along the thickness direction of the first wall 201, and the pressure relief mechanism 213, the support structure 215, and the first wall 201 are connected by the same welding seam.

[0265] The battery cell further includes a protection sheet 217 located on a side of the pressure relief mechanism 213 distal from the electrode assembly 22. A side of the connection portion 2133 distal from the electrode assembly 22 is provided with a stepped structure 2137, and the protection sheet 217 is fixed to a bottom wall of the stepped structure 2137, and a side of the body portion 2131 distal from the electrode assembly 22 does not exceed the bottom wall of the stepped structure 2137. Alternatively, the protection sheet 217 is fixed to a side of the first wall 201 distal from the electrode assembly 22, and the protection sheet 217 covers a weld between the pressure relief mechanism 213 and the first wall 201.

[0266] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized by, The shell (211) has a first wall (201) provided with a pressure relief hole (202); an electrode assembly (22) is accommodated in the shell (211); a pressure relief mechanism (213) covers the pressure relief hole (202), and the base material of the pressure relief mechanism (213) is iron; wherein the pressure relief mechanism (213) comprises a weak portion (2132), a body portion (2131) and a connecting portion (2133), the weak portion (2132) is configured to be destroyed to release pressure when the pressure inside the shell (211) reaches a threshold value, the body portion (2131) is located in the area surrounded by the weak portion (2132), and the connecting portion (2133) is located outside the weak portion (2132) and is used to connect the first wall (201); the body portion (2131) is a protruding structure that protrudes towards the direction close to the electrode assembly (22) or away from the electrode assembly (22). The material of the pressure relief mechanism (213) comprises stainless steel and / or carbon steel. The electrode assembly (22) comprises at least two layers of electrode sheets; The at least two layers of electrode sheets are arranged in a stacking manner, and the stacking direction of the at least two layers of electrode sheets is a first direction; or the at least two layers of electrode sheets are arranged in a winding manner, and each of the at least two layers of electrode sheets comprises a planar section located in the middle of the electrode assembly (22) and a curved section located at both ends of the electrode assembly (22), and the stacking direction of the at least two layers of electrode sheets at the planar section is the first direction; The cross section of the body portion (2131) in at least one plane perpendicular to the first direction is arc-shaped.

2. The battery cell of claim 1, wherein, The protruding height of the body portion (2131) relative to the weak portion (2132) is in the range of [0.5mm, 4mm].

3. The battery cell according to claim 1 or 2, characterized in that, The protruding height of the body portion (2131) relative to the weak portion (2132) is in the range of [0.8mm, 2mm]. The connecting portion (2133) comprises a fixed area (2135) and a transition area (2136), the fixed area (2135) is used to connect with the first wall (201), the transition area (2136) is used to connect the fixed area (2135) and the weak portion (2132), and the fixed area (2135) is arranged in parallel relative to the first wall (201), The transition area (2136) is flush with the fixed area (2135), or the transition area (2136) protrudes towards the direction close to the electrode assembly (22) relative to the fixed area (2135); 4. The battery cell according to any one of claims 1 to 3, characterized in that, The body portion (2131) protrudes towards the direction close to the electrode assembly (22) relative to the fixed area (2135).

5. The battery cell according to any one of claims 1 to 4, characterized in that, ​ 6. The battery cell according to any one of claims 1 to 5, characterized in that, ​ ​ ​ 7. The battery cell according to any one of claims 1 to 5, characterized in that, The connecting portion (2133) comprises a fixing area (2135) for connecting with the first wall (201) and a transition area (2136) for connecting the fixing area (2135) with the weak portion (2132), the fixing area (2135) is arranged in parallel with respect to the first wall (201), The transition area (2136) and the body portion (2131) are both protruded with respect to the weak portion (2132) in a direction away from the electrode assembly (22).

8. The battery cell according to claim 6 or 7, characterized in that The transition area (2136) is protruded with respect to the fixing area (2135) in a direction close to the electrode assembly (22), and the inclination angle of the transition area (2136) with respect to the fixing area (2135) ranges from 40° to 75°.

9. The battery cell of any one of claims 1 to 8, wherein, The thickness of the shell (211) ranges from 0.075mm to 0.4mm; and / or, The thickness of the body portion (2131) ranges from 0.075mm to 0.4mm.

10. The battery cell of any one of claims 1 to 9, wherein, The thickness of the shell (211) ranges from 0.075mm to 0.25mm; and / or, The thickness of the body portion (2131) ranges from 0.075mm to 0.25mm.

11. The battery cell of any one of claims 1 to 10, wherein, The base material of the shell (211) is iron.

12. The battery cell of any one of claims 1 to 11, wherein, The battery cell further comprises: A support structure (215) fixed to the side of the first wall (201) facing the electrode assembly (22), the pressure relief mechanism (213) is located on the side of the support structure (215) away from the electrode assembly (22), the pressure relief mechanism (213) is welded to the support structure (215) and the At least one of the first wall (201).

13. The battery cell of claim 12, wherein, The support structure (215) and the first wall (201) are fixed by welding or by adhesion.

14. The battery cell according to claim 12 or 13, characterized in that, The materials of the pressure relief mechanism (213), the support structure (215) and the first wall (201) all comprise iron, copper or titanium.

15. The battery cell of any one of claims 12 to 14, wherein, The surface of the pressure relief mechanism (213) facing the electrode assembly (22) does not exceed the surface of the support structure (215) facing the electrode assembly (22).

16. The battery cell of any one of claims 12 to 15, wherein, The thickness of the support structure (215) ranges from 0.4mm to 1.5mm.

17. The battery cell of any one of claims 12 to 16, wherein, The thickness of the support structure (215) ranges from 0.4mm to 0.8mm.

18. The battery cell of any one of claims 12-17, wherein, The battery cell further comprises: A protection piece (216) fixed to the side of the first wall (201) facing the electrode assembly (22), the surfaces of the support structure (215) and the pressure relief mechanism (213) facing the electrode assembly (22) are both protruded from the surface of the first wall (201) facing the electrode assembly (22), and the surface (2161) of the protection piece (216) facing the electrode assembly (22) is protruded from the surfaces of the support structure (215) and the pressure relief mechanism (213) facing the electrode assembly (22).

19. The battery cell of claim 18, wherein, The protection piece (216) comprises a first part (2163) and a second part (2164) arranged at intervals, and the pressure relief mechanism (213) and the support structure (215) are located between the first part (2163) and the second part (2164).

20. The battery cell of claim 18, wherein, The protection piece (216) is provided with a avoiding opening (2162) for avoiding the pressure relief mechanism (213) and the support structure (215).

21. The battery cell of claim 18, wherein, The protection piece (216) is provided with a groove (2166) opening towards the pressure relief mechanism (213), which is used to accommodate the pressure relief mechanism (213) and the support structure (215), and the bottom of the groove (2166) is provided with a thinning area (2167) corresponding to the pressure relief mechanism (213), and the thickness of the thinning area (2167) is less than that of other areas of the bottom of the groove (2166).

22. The battery cell of any one of claims 12-21, wherein, The pressure relief mechanism (213), the inner wall of the pressure relief hole (202) and the support structure (215) are connected by the same welding seam, and the same welding seam is located on the side of the support structure (215) away from the electrode assembly (22).

23. The battery cell of any one of claims 12-21, wherein, The pressure relief mechanism (213) and the support structure (215) are connected by the same welding seam, and the first wall (201) and the support structure (215) are connected by the same welding seam, and the welding seam between the pressure relief mechanism (213) and the support structure (215) is different from the welding seam between the first wall (201) and the support structure (215).

24. The battery cell of any one of claims 12-21, wherein, The pressure relief mechanism (213), the support structure (215) and the first wall (201) are arranged in a stacking manner along the thickness direction of the first wall (201), and the pressure relief mechanism (213), the support structure (215) and the first wall (201) are connected by the same welding seam.

25. The battery cell of any one of claims 12-24, wherein, The pressure relief mechanism (213), the support structure (215) and the first wall (201) have at least one welding seam, Along the thickness direction of the first wall (201), the orthographic projection of the at least one welding seam towards the outer surface of the support structure (215) is located in the middle region of the outer surface of the support structure (215), and the outer surface of the support structure (215) is the surface of the support structure (215) away from the electrode assembly (22).

26. The battery cell of claim 25, wherein, Along the thickness direction of the first wall (201), the orthographic projection of the at least one welding seam towards the outer surface of the support structure (215) is symmetrically distributed relative to the center line of the outer surface of the support structure (215).

27. The battery cell of claim 25 or 26, wherein, The side of the welding seam towards the electrode assembly (22) does not exceed the surface of the support structure (215) towards the electrode assembly (22).

28. The battery cell of any one of claims 1-27, wherein, The battery monomer further comprises: A protection sheet (217) located on the side of the pressure relief mechanism (213) away from the electrode assembly (22). ​ 29. The battery cell of claim 28, wherein, A step structure (2137) is arranged on the side of the connecting portion (2133) away from the electrode assembly (22), and the protective sheet (217) is fixed to the bottom wall of the step structure (2137), and the side of the body portion (2131) away from the electrode assembly (22) does not exceed the bottom wall of the step structure (2137).

30. The battery cell of claim 28, wherein, The protective sheet (217) is fixed to the side of the first wall (201) away from the electrode assembly (22), and the protective sheet (217) covers the weld joint between the pressure relief mechanism (213) and the first wall (201).

31. A battery device, characterized by Comprising: a plurality of battery cells as claimed in any of claims 1 to 30.

32. An electrical device, comprising: Comprising: a battery device comprising a battery cell as claimed in any of claims 1 to 30, the battery device being configured to power the electrical consumer.

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