Battery cells, batteries and electrical equipment

Abstract

This application provides a battery cell, a battery, and an electrical device, belonging to the battery field. The battery cell includes an electrode assembly, a housing, and a pressure release structure. The housing accommodates the electrode assembly, and the pressure release structure is provided at the bottom of the housing and is integrally molded with the housing. When the battery cell is in normal use, the pressure release structure is located at the bottom of the housing. Unlike the prior art where the pressure release structure is welded to the cap, this application integrally molds the pressure release structure with the housing, thereby avoiding leakage due to welding defects. Furthermore, the pressure release structure's ability to withstand external impacts is improved. Furthermore, the electrolyte in the housing can cause creep or impacts to the pressure release structure. However, by integrally molding the pressure release structure with the housing, the rigidity of the pressure release structure is improved, thereby enabling the pressure release structure to withstand creep and impacts caused by the electrolyte, thereby contributing to extending the life of the pressure release structure and reducing the risk of leakage from the pressure release structure.

Description

[Technical Field]

[0001] The present application is in the field of batteries, and specifically relates to battery cells, batteries, and electrical devices. [Background technology]

[0002] Batteries are widely used in new energy applications such as electric vehicles and new energy vehicles, and new energy vehicles and electric vehicles have become a new trend in the development of the automobile industry. Battery caps are provided with pressure release structures for releasing internal pressure when the internal pressure of the battery reaches a release pressure. However, pressure release structures are prone to leakage. Summary of the Invention

[0003] The embodiments of the present application aim to provide a battery cell, a battery, and an electrical device that can improve the problem of pressure release structures in the related art being prone to liquid leakage.

[0004] In a first aspect, an embodiment of the present application provides a battery cell, the battery cell including an electrode assembly, a housing, and a pressure release structure, the housing accommodating the electrode assembly, and the pressure release structure being provided at a lower part of the housing and being integrally molded with the housing.

[0005] In the above solution, the pressure release structure is located at the bottom of the housing when the battery cell is in normal use. Unlike the prior art where the pressure release structure is welded to the cap, the present application integrally molds the pressure release structure with the housing, thereby avoiding leakage due to welding defects and improving the pressure release structure's ability to withstand external impacts. Furthermore, the electrolyte in the housing can cause creep or impacts on the pressure release structure. By integrally molding the pressure release structure with the housing, the rigidity of the pressure release structure is improved, making it more resistant to creep and impacts caused by the electrolyte, contributing to extending the life of the pressure release structure and reducing the risk of leakage.

[0006] In one alternative embodiment of the present application, the pressure release structure is provided in a portion of the housing below a mid-vertical plane perpendicular to the height direction of the housing.

[0007] In the above solution, the pressure from the electrolyte is relatively large in the height direction of the housing below the mid-vertical plane, making the pressure release structure more susceptible to leakage. In the present application, the pressure release structure is integrally molded with the housing, compared to the configuration in which the pressure release structure is provided below the mid-vertical plane in the height direction of the housing, thereby improving the strength and rigidity of the pressure release structure, improving the pressure release structure's ability to withstand impact and creep, and reducing the risk of leakage from the pressure release structure.

[0008] In one alternative embodiment of the present application, the housing has a wall that supports the electrode assembly in the direction of gravity, and the pressure release structure is provided on the wall and is integrally molded with the wall.

[0009] In the above proposal, the wall supports the electrode assembly in the direction of gravity, and the pressure of the electrolyte against the wall is the greatest, so if leakage occurs in the pressure release structure, the outflow rate and amount of electrolyte will be relatively large. In the present application, the pressure release structure is integrally molded with the wall, which supports the electrode assembly, thereby improving the strength and rigidity of the pressure release structure, improving the ability of the pressure release structure to withstand impact and creep, and reducing the risk of leakage from the pressure release structure.

[0010] As an alternative embodiment of the present application, the housing includes a wall portion, the pressure release structure is provided on the wall portion, the wall portion has an open area, the wall portion has a first surface and a second surface facing each other in the thickness direction, the pressure release structure includes a score groove, the score groove is recessed along a direction from the first surface to the second surface, the score groove is provided along the periphery of the open area, and the open area is configured to be openable with the score groove as a boundary.

[0011] In the above proposal, the score grooves can be formed by pressing or cold heading, which causes cold work hardening on the groove walls of the score grooves (changing the arrangement of crystal grains, causing crystal lattice distortion, reducing the plasticity of the metal, and increasing the hardness of the material), improving the ability to withstand external impacts and making the material less susceptible to damage from external impacts, thereby contributing to reducing the risk of liquid leakage from the pressure release structure.

[0012] As an optional embodiment of the present application, the pressure release structure includes at least one stage of cut grooves, the at least one stage of cut grooves being arranged in sequence on the wall portion along a direction from the first surface to the second surface, and the first groove bottom wall of the cut groove in the stage farthest from the first surface has the open area.

[0013] In the above proposal, at least one stage of notches and score grooves are formed in the wall in a sequential order from the first surface to the second surface. By forming the notches and score grooves in a sequential order during molding, the molding force on the wall is reduced, reducing the risk of cracks occurring in the wall and preventing the release structure from failing due to cracks at the score groove locations, thereby improving the long-term reliability of the pressure release device. The at least one stage of notches and score grooves can be formed using methods such as pressing or cold heading. This causes cold work hardening in the groove walls of the notches and score grooves (changing the crystal grain arrangement, causing crystal lattice distortion, reducing the metal's plasticity, and increasing the material's hardness), improving their ability to withstand external impacts and making them less susceptible to damage from external impacts. This contributes to reducing the risk of liquid leakage from the pressure release structure.

[0014] As an alternative embodiment of the present application, the pressure release structure includes two stages of the cut grooves, and the two stages of the cut grooves are arranged in sequence along a direction from the first surface to the second surface, with one stage of the cut grooves being arranged on the first surface, the other stage of the cut grooves being arranged on the bottom surface of the one stage of the cut grooves, and the score grooves being arranged on the bottom surface of the other stage of the cut grooves.

[0015] In the above proposal, when a two-stage score groove is provided, the number of forming steps is relatively small, and forming is relatively simple. In addition, due to cold work hardening, the rigidity, strength, and hardness of the wall surface of the score groove are effectively improved, and the risk of liquid leakage from the pressure release structure can be effectively reduced, contributing to improved production efficiency and reduced production costs.

[0016] As an optional embodiment of the present application, the pressure release structure includes a plurality of stages of score grooves, the stages of score grooves being arranged in order along the direction from the first surface to the second surface, and between two adjacent stages of score grooves, the score groove of the stage farther from the first surface is arranged on the bottom surface of the score groove of the stage closer to the first surface.

[0017] In the above proposal, if the multiple score grooves are formed in sequence from the first surface to the second surface, the forming depth of each score groove can be reduced, the forming force applied to the wall when forming each score groove in sequence, and the risk of cracking in the wall can be reduced. In the process of forming the multiple score grooves in sequence from the first surface to the second surface, the hardness of the portion of the wall remaining in the region where the score grooves are to be formed increases accordingly in accordance with the number of score groove processing stages, thereby increasing the hardness of the portion of the wall remaining after the multiple score grooves have been formed, further improving long-term reliability, improving the ability to withstand impact, and reducing the likelihood of breakage when subjected to an external impact.

[0018] As an alternative to the embodiment of the present application, a surface of the open region away from the first surface and the second surface are aligned in the thickness direction.

[0019] In the above proposal, the open area does not protrude from the second surface in the thickness direction, which reduces the space occupied by the open area inside the battery cell or battery, contributing to improving the energy density of the battery.

[0020] As an optional embodiment of the present application, a portion of the wall portion protrudes from the second surface in a direction away from the first surface to form a reinforcing portion, and the reinforcing portion is provided on the outer periphery of the open area so as to surround the open area.

[0021] In the above proposal, a portion of the wall portion protrudes from the second surface in a direction away from the first surface to form a reinforcing portion. Therefore, when the wall portion deforms, the reinforcing portion can reduce the impact of the deformation on the score groove, thereby reducing the risk of liquid leakage from the pressure release structure.

[0022] As an alternative to the embodiment of the present application, a surface of the open region away from the first surface and a surface of the reinforcing portion away from the first surface are aligned in the thickness direction.

[0023] In the above proposal, the open area does not protrude in the thickness direction toward the surface of the reinforcing part that is away from the first surface, which reduces the internal space occupied by the open area in the battery cell or battery, contributing to improving the energy density of the battery.

[0024] As an alternative to the embodiment of the present application, when the height of the reinforcing portion projecting from the second surface in the thickness direction is A, A satisfies 0.5 mm≦A≦4 mm.

[0025] In the above proposal, if the height of the reinforcing portion protruding from the second surface in the thickness direction is kept within 0.5 to 4 mm, the reinforcing effect of the reinforcing portion is improved, and it does not occupy a large amount of internal space in the battery cell or battery, thereby ensuring a higher energy density of the battery. When A<0.5 mm, the height of the reinforcing portion protruding from the second surface in the thickness direction is relatively small, and the reinforcing effect is not significant. When A>4 mm, the height of the reinforcing portion protruding from the second surface in the thickness direction is relatively large, and it occupies a large amount of space, which affects the energy density of the battery.

[0026] As an alternative to the embodiment of the present application, 1 mm≦A≦2.5 mm is satisfied.

[0027] In the above proposal, if the height of the reinforcing portion protruding from the second surface in the thickness direction is kept within the range of 1 to 2.5 mm, the reinforcing effect of the reinforcing portion is further improved, and the space it occupies inside the battery cell or battery becomes relatively small.

[0028] In one alternative embodiment of the present application, the open area is curved along the thickness direction.

[0029] In the above proposal, by designing the open area to bend along the thickness direction, when the wall receives an external impact, the wall can deform along the bending direction, absorbing the energy of the external impact and reducing the impact's impact on the score groove location, thereby preventing damage to the score groove location due to the external impact to some extent. Furthermore, the curved open area serves as a stress concentration area during pressure release, allowing the first groove bottom wall to more easily release at the score groove location. For the same release pressure, the score groove depth can be made shallower, allowing the first groove bottom wall to be thicker at the score groove location. This makes it less likely for the first groove bottom wall to open at the score groove location due to external influence, thereby reducing the risk of liquid leakage from the pressure release structure.

[0030] In one alternative embodiment of the present application, the open area is curved along a direction from the second surface to the first surface.

[0031] In the above proposal, when the open area bends from the second surface to the first surface, gas inside the battery cell acts on the open area, generating a tensile force at the location of the score groove on the first groove bottom wall. This allows the first groove bottom wall to easily open at the location of the score groove. For the same release pressure, the depth of the score groove can be made shallower, and the thickness of the first groove bottom wall at the location of the score groove can be made greater. This makes it less likely for the first groove bottom wall to open at the location of the score groove due to external influences, thereby reducing the risk of leakage from the pressure release structure. When the electrolyte acts on the open area, the force is relatively small, generating a tensile force at the location of the score groove on the first groove bottom wall, but it does not open the score groove. Furthermore, the tensile force generated at the location of the score groove on the first groove bottom wall distributes the force of the electrolyte, reducing the amplitude of the open area and making the pressure release structure less likely to open due to the action of the electrolyte, thereby reducing the risk of leakage from the pressure release structure.

[0032] As an alternative embodiment of the present application, the pressure release structure includes at least one stage of cut grooves, the at least one stage of cut grooves being provided in order on the wall portion along a direction from the first surface to the second surface, the open region being provided on a first groove bottom wall of the cut groove of the stage farthest from the first surface, the first groove bottom wall including a main body region, the main body region being provided surrounding the open region, the score groove being provided between the open region and the main body region, the main body region having a third surface and a fourth surface in the thickness direction, a distance between the third surface and the fourth surface being B, the open region having a fifth surface away from the second surface, the third surface and the fifth surface being located on the same side of the first groove bottom wall, and a maximum distance between the third surface and the fifth surface being C, whereby B / 10≦C≦B is satisfied.

[0033] In the above proposal, the distance between the third and fourth surfaces in the thickness direction is 1 to 10 times the maximum distance between the third and fifth surfaces in the thickness direction, which represents the degree of bending of the open area. If C>B, the degree of bending of the open area becomes excessive, and cracks are likely to occur at the score groove location on the bottom wall of the first groove due to the action of external impact. C

[0034] In one alternative embodiment of the present application, the first surface is an outer surface of the wall.

[0035] In the above proposal, when the first surface is the outer surface of the wall portion, the position of the first groove bottom wall is away from the first surface in the thickness direction. In this way, the score groove provided in the first groove bottom wall is less susceptible to the action of external impact, and the pressure release structure is less likely to open due to external impact, thereby reducing the risk of liquid leakage from the pressure release structure.

[0036] ​As an alternative embodiment of the present application, the pressure release structure includes at least one step of cut grooves, the at least one step of cut grooves being sequentially provided on the wall portion along a direction from the first surface to the second surface, the cut groove of the step farthest from the first surface having the open region at a first groove bottom wall, the wall portion having a strength D1, the second groove bottom wall of the cut groove of the step closest to the first surface having a strength D2, and the first groove bottom wall having a strength D3 where the score groove is located, satisfying D3 > D2 ≧ D1; and / or the wall portion having a hardness E1, the second groove bottom wall having a hardness E2, and the first groove bottom wall having a hardness E3 where the score groove is located, satisfying E3 > E2 ≧ E1. And / or the stiffness of the wall portion is F1, the stiffness of the second groove bottom wall is F2, and the stiffness of the first groove bottom wall at the location of the score groove is F3, and F3>F2≧F1 is satisfied.

[0037] In the above proposal, if the strength of the second groove bottom wall is greater than the strength of the wall portion, it is equivalent to providing a reinforcing component around the score groove. This reduces the risk of the first groove bottom wall being damaged at the score groove location when the wall portion receives an external impact, improving the pressure release structure's ability to withstand external impact. Furthermore, the strength of the first groove bottom wall at the score groove location is relatively high, but its hardness is also relatively high, reducing the material's ductility (making the material brittle) and allowing the valve to be easily opened by the action of internal gas. Therefore, for a given release pressure, the thickness of the first groove bottom wall at the score groove location is greater, improving its ability to withstand external impact and improving the long-term reliability of the pressure release structure. The cut grooves and score grooves can be formed using methods such as pressing or cold forging, which causes cold work hardening in the cut groove and score groove groove walls, thereby increasing the strength, rigidity, and hardness of the second groove bottom wall and the first groove bottom wall at the score groove location.

[0038] As an alternative to the embodiments of the present application, 1.2E1≦E2≦2.5E1 is satisfied.

[0039] In the above solution, the hardness of the second groove bottom wall is 1.2 to 2.5 times the hardness of the wall portion. In this way, the second groove bottom wall can stop an external object, and the risk that the external object acts on the position of the score groove can be reduced.

[0040] As an alternative solution of the embodiment of the present application, 2.5E1 < E3 ≤ 5E1 is satisfied.

[0041] In the above solution, the hardness of the portion of the first groove bottom wall where the score groove is located is 2.5 to 5 (excluding 2.5) times the hardness of the wall portion. In this way, the portion of the first groove bottom wall where the score groove is located becomes relatively brittle and can be easily opened by the action of the internal air pressure.

[0042] As an alternative solution of the embodiment of the present application, 5HBW ≤ E1 ≤ 150HBW is satisfied.

[0043] In the above solution, if the strength of the wall portion is 5 to 150HBW, the wall portion has the ability to withstand a relatively large impact and has relatively excellent resistance to external impacts.

[0044] As an alternative solution of the embodiment of the present application, 5HBW ≤ E3 ≤ 200HBW is satisfied.

[0045] In the above solution, if the strength of the portion of the first groove bottom wall where the score groove is located is 5 to 2000HBW, even if the wall portion receives an external impact, the portion of the first groove bottom wall where the score groove is located is not easily damaged, and the ability of the pressure relief structure to withstand external impacts is more excellent.

[0046] As an alternative solution of the embodiment of the present application, when the minimum thickness of the portion of the first groove bottom wall where the score groove is located is W1, 5HBW / mm ≤ E3 / W1 ≤ 10000HBW / mm is satisfied, and preferably, 190HBW / mm ≤ E3 / W1 ≤ 4000HBW / mm is satisfied.

[0047] The above proposal takes into consideration the impact of the thickness of the first groove bottom wall at the location of the score groove on the performance of the housing, and also the impact of the hardness of the first groove bottom wall at the location of the score groove on the performance of the housing. A setting of 5HBW / mm≦E3 / W1≦10,000HBW / mm ensures that the location of the score groove on the first groove bottom wall has sufficient strength under normal battery cell usage conditions, is resistant to fatigue damage, and can extend the service life of the battery cell. The housing also allows the open area to release pressure in a timely manner during thermal runaway of the battery cell, reducing the risk of battery cell explosion and improving battery cell safety. A setting of 190HBW / mm≦E3 / W1≦4,000HBW / mm ensures better overall housing performance, ensures that the open area can be released in a timely manner during thermal runaway of the battery cell, and ensures that the location of the first groove bottom wall at the location of the score groove has sufficient strength under normal battery cell usage conditions. On the premise of ensuring the safety of the battery cells, the service life of the battery cells can be extended.

[0048] As an optional example of an embodiment of the present application, when the minimum thickness of the wall portion at the location of the score groove is W1 and the minimum thickness of the wall portion is W2, the relationship 0.05≦W1 / W2≦0.95 is satisfied.

[0049] In the above proposal, the score grooves are formed in the wall portion by press forming or cold heading, and if W1 / W2 is within the range of 0.05 to 0.95, the crystal grains in the wall portion where the score grooves are located can be refined, improving the mechanical properties of the material in the wall portion where the score grooves are located, and improving the toughness and fatigue strength of the wall portion where the score grooves are located. This reduces the risk of the wall portion where the score grooves are located being damaged during normal use of the battery cell, extends the service life of the battery cell, and reduces the risk of the battery cell exploding in the event of thermal runaway.

[0050] As an alternative to the embodiments of the present application, 0.12≦W1 / W2≦0.8 is satisfied, and preferably 0.2≦W1 / W2≦0.5 is satisfied.

[0051] In the above proposal, if W1 / W2 is 0.12≦W1 / W2≦0.8, the overall performance of the wall is better, ensuring that the wall portion where the score groove is located will break in a timely manner when the battery cell experiences thermal runaway, and ensuring that the wall portion where the score groove is located has sufficient strength during normal use of the battery cell. If W1 / W2 is 0.2≦W1 / W2≦0.5, the risk of the wall portion where the score groove is located breaking under normal use conditions of the battery cell is reduced, ensuring that the wall portion where the score groove is located will break in a timely manner when the battery cell experiences thermal runaway, and improving the timeliness of pressure release.

[0052] As an alternative to the embodiment of the present application, 0.02 mm≦W1≦1.6 mm is satisfied, and preferably 0.06 mm≦W1≦0.4 mm is satisfied.

[0053] In the above proposal, if W1 is too small, it becomes difficult to form the score grooves, and the portion of the wall where the score grooves are located is easily damaged during the forming process. If W1 is too large, the portion of the wall where the score grooves are located is less likely to be destroyed during thermal runaway of the battery cell, making it more likely that pressure will not be released in a timely manner. Therefore, by making W1 0.02 mm ≦ W1 ≦ 1.6 mm, it is possible to reduce the difficulty of forming the score grooves and improve the timeliness of pressure release during thermal runaway of the battery cell. By making W1 0.06 mm ≦ W1 ≦ 0.4 mm, it is possible to further reduce the difficulty of forming the score grooves and improve the timeliness of pressure release during thermal runaway of the battery cell.

[0054] As an alternative to the embodiment of the present application, 1 mm≦W2≦5 mm is satisfied, preferably 1.2 mm≦W2≦3.5 mm is satisfied, and more preferably 2 mm≦W2≦3 mm is satisfied.

[0055] In the above proposals, if W2 is too large, the wall thickness will be relatively large, the housing will use more material, the housing will be heavy, and it will be less economical. If W2 is too small, the wall thickness will be relatively small, and the housing will have less ability to withstand deformation. Therefore, by making W2 1 mm ≦ W2 ≦ 5 mm, the housing will be more economical and have better ability to withstand deformation. By making W2 1.2 mm ≦ W2 ≦ 3.5 mm, the housing will be more economical and have better ability to withstand deformation.

[0056] As an alternative embodiment of the present application, the pressure release structure includes at least one stage of cut grooves, the at least one stage of cut grooves being arranged in sequence on the wall portion along the direction from the first surface to the second surface, the open area being in the first groove bottom wall of the cut groove in the stage farthest from the first surface, the average size of the crystal grains in the wall portion being G1, the average size of the crystal grains in the second groove bottom wall of the cut groove in the stage closest to the first surface being G2, and the average size of the crystal grains in the first groove bottom wall at the location where the score groove is located being G3, so that G1>G2>G3 is satisfied.

[0057] In the above proposal, when the cut grooves and score grooves are formed by pressing or cold heading, the crystal grains of the material are broken down and refined, so that the average size of the crystal grains at the location of the score groove on the bottom wall of the first groove is smaller than the average size of the crystal grains on the bottom wall of the second groove, which in turn is smaller than the average size of the crystal grains in the wall portion.

[0058] As an alternative to the embodiments of the present application, G3 / G1≦0.9 is satisfied.

[0059] In the above proposal, the difference between the average crystal grain size of the portion of the first groove bottom wall where the score groove is located and the average crystal grain size of the wall portion is relatively large, and by reducing the average crystal grain size of the portion of the first groove bottom wall where the score groove is located, the mechanical properties of the material of the portion of the first groove bottom wall where the score groove is located can be improved, and the toughness and fatigue strength of the portion of the first groove bottom wall where the score groove is located can be further improved.

[0060] As an alternative to the embodiments of the present application, G3 / G1≧0.05 is satisfied, and preferably, 0.1≦G3 / G1≦0.5 is satisfied.

[0061] In the above proposal, if G3 / G1 is too small, it becomes difficult to form the notched grooves and score grooves, and the strength of the portion of the first groove bottom wall where the score grooves are located becomes too high, making it difficult for the portion of the first groove bottom wall where the score grooves are located to break during thermal runaway of the battery cell, and making it difficult to release pressure in a timely manner. Therefore, by making G3 / G1 ≥ 0.05, the difficulty of forming the notched grooves and score grooves can be reduced and the timeliness of pressure release during thermal runaway of the battery cell can be improved. By making 0.1 ≤ G3 / G1 ≤ 0.5, the overall performance of the wall is improved, ensuring that the portion of the first groove bottom wall where the score grooves are located breaks in a timely manner during thermal runaway of the battery cell, and ensuring that the portion of the first groove bottom wall where the score grooves are located has sufficient strength during normal use of the battery cell.

[0062] As an alternative to the embodiments of the present application, 0.4 μm≦G3≦75 μm is satisfied, and preferably 1 μm≦G3≦10 μm is satisfied.

[0063] In the above proposal, if G3 is too large, the toughness and fatigue strength of the portion of the first groove bottom wall where the score groove is located will be relatively low. If G3 is too small, the difficulty of forming the notch grooves and score grooves will be relatively high, and the strength of the portion of the first groove bottom wall where the score groove is located will be excessive, making the portion of the first groove bottom wall where the score groove is located less likely to break during thermal runaway of the battery cell and more likely to result in inability to release pressure in a timely manner. Therefore, by making G3 0.4 μm≦G3≦75 μm, on the one hand, the difficulty of forming the notch grooves and score grooves will be reduced and the timeliness of pressure release during thermal runaway of the battery cell will be improved. On the other hand, on the other hand, the toughness and fatigue strength of the portion of the first groove bottom wall where the score groove is located will be improved, reducing the risk of the portion of the first groove bottom wall where the score groove is located breaking during normal use of the battery cell.

[0064] As an alternative to the embodiments of the present application, the range of 10 μm≦G1≦150 μm is satisfied, and preferably the range of 30 μm≦G1≦100 μm is satisfied.

[0065] As an optional example of an embodiment of the present application, when the minimum thickness of the first groove bottom wall at the location of the score groove is W1 and the average size of the crystal grains of the first groove bottom wall at the location of the score groove is G3, the relationship 1≦W1 / G3≦100 is satisfied, and preferably the relationship 5≦W1 / G3≦20 is satisfied.

[0066] In the above proposal, if W1 / G3 is too small, the fewer the number of crystal particle layers at the location of the score groove on the first groove bottom wall in the thickness direction of the wall portion, the smaller the fatigue strength of the location of the score groove on the first groove bottom wall; if W1 / G3 is too large, the number of crystal particle layers at the location of the score groove on the first groove bottom wall in the thickness direction will be too large, and the strength of the location of the score groove on the first groove bottom wall will be too large, resulting in a risk that the location of the score groove on the first groove bottom wall will not be destroyed in a timely manner when the battery cell experiences thermal runaway. Therefore, by satisfying 1≦W1 / G3≦100, on the one hand, the number of crystal grain layers in the thickness direction at the portion of the first groove bottom wall where the score groove is located is relatively large, the fatigue strength of the portion of the first groove bottom wall where the score groove is located is increased, and the risk of the portion of the first groove bottom wall where the score groove is located being destroyed under normal use conditions of the battery cell is reduced. On the other hand, on the other hand, the portion of the first groove bottom wall where the score groove is located is more likely to be destroyed in a timely manner and release pressure in a timely manner during thermal runaway of the battery cell. By satisfying 5≦W1 / G3≦20, the overall performance of the wall portion is further improved, ensuring that the portion of the first groove bottom wall where the score groove is located is not destroyed in a timely manner during thermal runaway of the battery cell, and ensuring that the portion of the first groove bottom wall where the score groove is located has sufficient fatigue strength under normal use conditions of the battery cell, thereby extending the service life of the battery cell.

[0067] In one alternative embodiment of the present application, the housing includes a housing body and a cap, the housing body has an opening, the cap is connected to the housing body to seal the opening, and the pressure release structure is provided on the cap.

[0068] In the above solution, the pressure release structure is provided on the cap, and the cap is located at the bottom of the housing body to accommodate the scenario where the battery cell is used upside down.

[0069] In one alternative embodiment of the present application, the housing includes a housing body and a cap, the housing body has an opening, the cap is connected to the housing body to seal the opening, and the pressure release structure is provided on the housing body.

[0070] In the above proposal, the pressure release structure is provided on the housing body, and the pressure release structure is located at the bottom of the housing body.

[0071] As an alternative to the embodiment of the present application, the housing body has openings at both ends in the first direction, the housing includes two caps, and the caps close the openings in a one-to-one relationship.

[0072] In a second aspect, an embodiment of the present application further provides a battery, the battery including the battery cell described above.

[0073] In a third aspect, an embodiment of the present application further provides an electric device, the electric device including the battery described above, the battery providing electric energy to the electric device. In order to more clearly explain the technical solutions of the embodiments of the present application, the drawings necessary for the description of the embodiments will be briefly described below. The drawings described are only for illustrating some embodiments of the present application and are not intended to limit the scope. Those skilled in the art can obtain other related drawings based on these drawings without using inventive abilities. [Brief explanation of the drawings]

[0074] [Figure 1] 1 is a schematic diagram of a vehicle according to some embodiments of the present application. [Figure 2] FIG. 1 is an exploded view of a battery according to some embodiments of the present application. [Figure 3] FIG. 1 is a schematic diagram of a battery cell according to some embodiments of the present application. [Figure 4] FIG. 1 is an exploded view of a battery cell according to some embodiments of the present application. [Figure 5]1A-1C are schematic diagrams of wall sections according to some embodiments of the present application. [Figure 6] 1 is a schematic plan view of a wall according to some embodiments of the present application; [Figure 7] FIG. 7 is a cross-sectional view of a portion II in FIG. 6. [Figure 8] FIG. 8 is an enlarged view of a portion J in FIG. 7. [Figure 9] 10A-10C are schematic plan views of walls according to some other embodiments of the present application. [Figure 10] FIG. 10 is a cross-sectional view of a portion LL in FIG. 9. [Figure 11] FIG. 11 is an enlarged view of a portion M in FIG. [Figure 12] 10A-10C are schematic plan views of walls according to some other embodiments of the present application. [Figure 13] FIG. 13 is a cross-sectional view of a portion NN in FIG. [Figure 14] FIG. 14 is an enlarged view of a portion Q in FIG. [Figure 15] FIG. 13 is a cross-sectional view of a portion PP in FIG. [Figure 16] FIG. 16 is an enlarged view of the R portion in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0075] In order to more clearly explain the objectives, technical solutions and advantages of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely explained below with reference to the drawings used in the embodiments of the present application. The described embodiments are only some of the embodiments of the present application, and are not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without using inventive ability also fall within the scope of protection of the present application.

[0076] Unless otherwise specified, all technical and scientific terms used in this application have the meanings commonly understood by those skilled in the art. The terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "comprise," "have," and any variations thereof in the specification, claims, and above-mentioned drawings of this application mean a non-exclusive inclusion. The terms "first," "second," etc. in the specification, claims, or drawings of this application are only intended to distinguish between different elements and do not stipulate a particular order or primary and secondary elements.

[0077] The term "embodiment" in this application means that a particular feature, configuration, or characteristic described using the embodiment is included in at least one embodiment of this application. The use of this term in various parts of the specification does not necessarily refer to the same embodiment, nor is it intended to limit an embodiment to an independent or alternative embodiment that is mutually exclusive from other embodiments.

[0078] In the description of this application, unless otherwise specified, the terms "attach," "couple," "connect," and "attach" should be understood in a broad sense. For example, they may refer to a fixed connection, a detachable connection, or an integral connection. They may be directly connected, indirectly connected via an intermediate, or the interiors of two elements may be in communication. Those skilled in the art will be able to understand the specific meanings of the above terms in this application depending on the specific circumstances.

[0079] The term "and / or" used in this application is merely for explaining the relationship between related objects and represents three types of relationships, for example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the symbol " / " in this application generally represents the relationship indicated by "or" between the related objects before and after it.

[0080] In the embodiments of the present application, like reference numerals refer to like parts, and for the sake of simplicity, detailed descriptions of like parts will be omitted in different embodiments. The dimensions such as thickness, length, etc. of various parts in the embodiments of the present application shown in the drawings, and the dimensions such as thickness, length, width, etc. of the entire integrated device are for illustrative purposes only and do not limit the present application.

[0081] As used in this application, "plurality" means two or more.

[0082] In this application, battery cells include lithium ion secondary batteries, lithium ion primary batteries, lithium-sulfur batteries, sodium lithium ion batteries, sodium ion batteries, magnesium ion batteries, etc., but are not limited to these in the examples of this application. Battery cells may be cylindrical, laminated, rectangular, or have other shapes, but are not limited to these in the examples of this application. Battery cells are generally divided into three types based on packaging methods: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, but are not limited to these in the examples of this application.

[0083] In the embodiments of this application, a battery refers to a physical unit that includes one or more battery cells, thereby providing higher voltage and capacity. For example, the battery described in this application includes a battery module or a battery pack. A battery generally includes a housing for packaging one or more battery cells. The housing can prevent liquids or other foreign substances from affecting the charging and discharging of the battery cells.

[0084] A battery cell includes an electrode assembly and an electrolyte, with the electrode assembly consisting of a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell functions primarily through the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is applied to the surface of the positive electrode current collector. The portion of the positive electrode current collector that is not coated with the positive electrode active material layer protrudes beyond the portion of the positive electrode current collector that is coated with the positive electrode active material layer, and the portion of the positive electrode current collector that is not coated with the positive electrode active material layer serves as a positive electrode tab. Taking a lithium-ion battery as an example, the positive electrode current collector is made of aluminum, and the positive electrode active material is lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganese oxide, or the like. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is applied to the surface of the negative electrode current collector. The portion of the negative electrode current collector where the negative electrode active material layer is not applied protrudes from the portion of the negative electrode current collector where the negative electrode active material layer is applied, and the portion of the negative electrode current collector where the negative electrode active material layer is not applied serves as a negative electrode tab. The negative electrode current collector may be made of copper, and the negative electrode active material may be carbon-based or silicon-based. To ensure that they do not melt when a large current flows, both the positive electrode tab and the negative electrode tab are stacked. Examples of materials for the separator include PP (polypropylene) and PE (polyethylene). The electrode assembly may have a wound structure or a stacked structure, and the embodiments of the present application are not limited thereto.

[0085] Currently, from the perspective of market development, the applications of batteries are becoming increasingly widespread. Batteries are not only used in energy storage power systems such as hydroelectric power plants, thermal power plants, wind power plants, and solar power plants, but also in many fields such as electric transportation such as electric bicycles, electric motorcycles, and electric cars, military equipment, and aerospace. As the applications of batteries expand, market demand is also increasing.

[0086] Battery technology takes into account many aspects of design, including performance parameters such as energy density, cycle life, discharge capacity, charge and discharge rate, and battery safety must also be considered.

[0087] In order to ensure the safety of the battery cell, in the prior art, a pressure release structure is welded to the cap of the battery cell, and a score groove is provided in the pressure release structure. The score groove defines a pressure release section, and when the internal pressure of the battery cell reaches the release pressure, the pressure release section opens to release the internal pressure of the battery cell, thereby reducing the risk of the battery cell exploding or catching fire.

[0088] In conventional technology, welding defects are likely to occur when welding a pressure release structure to a cap, causing electrolyte leakage from the battery cell. The inventors discovered through research that this problem is particularly exacerbated when the battery cell is used upside down. Furthermore, when welding a pressure release structure to a cap, the high temperatures caused by welding affect the score groove. Thermal expansion and cold contraction of the welding material stretch the score groove, shortening the lifespan of the pressure release structure. The pressure release structure is also prone to opening due to the action of the electrolyte, resulting in leakage. Furthermore, the pressure release structure is prone to opening due to external impact, causing leakage from the pressure release structure. Furthermore, when a battery cell is used upside down, the electrolyte inside the battery cell causes creep in the pressure release structure, shortening its lifespan and making it more susceptible to leakage.

[0089] In view of this, an embodiment of the present application provides a battery cell, which includes an electrode assembly, a housing, and a pressure release structure, wherein the housing accommodates the electrode assembly, and the pressure release structure is provided at a lower part of the housing and is integrally molded with the housing.

[0090] When the battery cell is in normal use, the pressure release structure is located at the bottom of the housing. Unlike conventional techniques in which the pressure release structure is welded to the cap, the pressure release structure and the housing are integrally molded, which prevents leakage due to welding defects and improves the pressure release structure's ability to withstand external impacts. Furthermore, the electrolyte in the housing can cause creep or impacts on the pressure release structure. By integrally molding the pressure release structure with the housing, the rigidity of the pressure release structure is improved, making it more resistant to electrolyte creep and impacts, contributing to extending the life of the pressure release structure and reducing the risk of leakage.

[0091] The technical solutions in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0092] Examples of electrical appliances include vehicles, mobile phones, portable devices, laptops, ships, aircraft, power toys, and power tools. Aircraft include airplanes, rockets, space shuttles, and spaceships. Power toys include both stationary and mobile devices, such as game consoles, toy electric cars, toy electric boats, and toy electric airplanes. Power tools include metal-cutting power tools, polishing power tools, assembly power tools, and railroad power tools, such as power drills, power grinders, power wrenches, power screwdrivers, power hammers, impact power drills, concrete vibrators, and power planers. The examples of the present application are not particularly limited to the above-mentioned electrical appliances.

[0093] For convenience of explanation, the electrical equipment will be described using the vehicle 1000 as an example.

[0094] Referring to FIG. 1, FIG. 1 is a schematic diagram of a vehicle 1000 according to some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a natural gas vehicle, or a new energy vehicle, and the new energy vehicle may be an electric vehicle, a hybrid vehicle, or a range-extended electric vehicle, etc. A battery 100 is disposed inside the vehicle 1000, and the battery 100 is disposed at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000, for example, as a power source for steering the vehicle 1000. The vehicle 1000 further includes a control device 200 and an engine 300, and the control device 200 controls the power supply from the battery 100 to the engine 300, for example, for starting the vehicle 1000, navigating, and supplying work electricity during driving.

[0095] In some embodiments of the present application, the battery 100 can be used not only as a power source for steering the vehicle 1000, but also as a power source for providing driving power to the vehicle 1000 in place of or partially replacing gasoline or natural gas.

[0096] Referring to FIG. 2, FIG. 2 is an exploded view of a battery 100 according to some embodiments of the present application. The battery 100 includes a housing 10 and battery cells 20, which are housed within the housing 10. The housing 10 provides a housing space for the battery cells 20 and may have various configurations. In some embodiments, the housing 10 includes a first portion 11 and a second portion 12, which, when combined with each other, define a housing space for housing the battery cells 20. The second portion 12 may have a hollow structure with an open end, and the first portion 11 may have a plate-like structure and the first portion 11 may cover the open side of the second portion 12, thereby defining the housing space. Alternatively, the first portion 11 and the second portion 12 may both have a hollow structure with an open end, and the open side of the first portion 11 may cover the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes such as a cylindrical body or a rectangular parallelepiped.

[0097] The battery 100 may include a plurality of battery cells 20, and the plurality of battery cells 20 may be connected in series, in parallel, or in a manner including both. The term "connected in a manner including both" refers to the plurality of battery cells 20 being connected in series and in parallel, and the plurality of battery cells 20 being connected in series and in parallel, or in a manner including both, and the integrated battery cells 20 may be housed within the housing 10. Of course, the battery 100 may first be formed by connecting the plurality of battery cells 20 in series and in parallel, or in a manner including both, to form a battery module, and then the plurality of battery modules may be further connected in series and in parallel, or in a manner including both, to form an integrated battery module, and then housed within the housing 10. The battery 100 may further include other structures, such as bus bars, for realizing electrical connection between the plurality of battery cells 20.

[0098] Each battery cell 20 may be a secondary battery cell or a primary battery cell, and may be, but is not limited to, a lithium-sulfur battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell. The battery cells 20 may be cylindrical, laminated, rectangular, or of other shapes.

[0099] 3, 4, 5, 6, 7, and 8, Fig. 3 is a schematic structural view of a battery cell 20 according to some embodiments of the present application, Fig. 4 is an exploded view of the battery cell 20 according to some embodiments of the present application, Fig. 5 is a schematic structural view of a wall portion 213 according to some embodiments of the present application, Fig. 6 is a schematic plan view of the wall portion 213 according to some embodiments of the present application, Fig. 7 is a cross-sectional view of part II in Fig. 6, and Fig. 8 is an enlarged view of part J in Fig. 7. An embodiment of the present application provides a battery cell 20, which includes an electrode assembly 22, a housing 21, and a pressure release structure 23, wherein the housing 21 accommodates the electrode assembly 22, and the pressure release structure 23 is provided at a lower part of the housing 21 and is integrally formed with the housing 21.

[0100] The battery cell 20 is the smallest constituent unit of the battery 100 .

[0101] The housing 21 includes a cap 211 and a housing body 212, and the housing body 212 has an accommodating space that is open at one end for accommodating the electrode assembly 22. The cap 211 is connected to the housing body 212 to seal the opening.

[0102] The cap 211 is a component that closes the opening of the housing body 212 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the cap 211 is not particularly limited as long as it can be matched to the shape of the housing body 212 and assembled to the housing body 212. Optionally, the cap 211 may be made of a material (e.g., aluminum alloy) with a certain hardness and strength. This makes the cap 211 less likely to deform when pressed or hit, improving the structural strength of the battery cell 20 and safety performance. The cap 211 may be provided with functional components such as electrode terminals (not shown). The electrode terminals are electrically connected to the electrode assembly 22 to output or input electrical energy to the battery cell 20. The material of the cap 211 may be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, or plastic, and is not particularly limited in the embodiments of the present application. In some embodiments, the battery cell 20 further includes an insulating member disposed inside the cap 211 to separate the electrical connection components in the housing body 212 from the cap 211, thereby reducing the risk of short circuits. Illustratively, the insulating member may be made of a material such as plastic or rubber.

[0103] The housing body 212, together with the cap 211, forms the internal environment of the battery cell 20. This internal environment accommodates the electrode assembly 22, electrolyte, and other components. The housing body 212 and the cap 211 may be separate components, or an opening may be formed in the housing body 212, which is then closed by the cap 211 to form the internal environment of the battery cell 20. The cap 211 and the housing body 212 may be integrated. Specifically, the cap 211 and the housing body 212 first form a common mating surface before other components are inserted into the housing. When the interior of the housing body 212 is closed, the cap 211 closes the housing body 212. The housing body 212 may have various shapes and dimensions, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. The shape of the housing body 212 may be determined based on the specific shape and dimensions of the electrode assembly 22. The material of the housing body 212 can be various, for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and is not particularly limited in the embodiment of the present application.

[0104] The electrode assembly 22 is a component that undergoes electrochemical reactions in the battery cell 20. The housing 21 accommodates one or more electrode assemblies 22. The electrode assembly 22 is primarily formed by winding or stacking positive and negative electrode sheets, and typically has a separator interposed between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets that contain active material form the main body of the electrode assembly 22, and the portions of the positive and negative electrode sheets that do not contain active material form tabs, respectively. The positive and negative electrode tabs are both located at one end of the main body, or at both ends of the main body. During the charge and discharge process of the battery 100, the positive and negative electrode active materials react with the electrolyte.

[0105] The pressure release structure 23 is a component that opens to release the internal pressure of the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches the release pressure.

[0106] It is assumed that there is one imaginary plane, and the imaginary plane is perpendicular to the height direction of the housing 21. In the height direction of the housing 21, the portion of the housing 21 above the imaginary plane accounts for 30% of the height of the housing 21, and the portion of the housing 21 below the imaginary plane accounts for 70% of the height of the housing 21. The lower part refers to the portion of the housing 21 below the imaginary plane in the height direction.

[0107] In FIG. 3, the height direction of the housing 21 is the direction indicated by H in the drawing.

[0108] The term "integral molding" refers to the fact that the housing 21 and the pressure relief structure 23 are integrally formed when provided. For example, the pressure relief structure 23 is formed on the housing 21 by a method such as pressing or cold heading.

[0109] When the battery cell 20 is in normal use, the pressure release structure 23 is located at the bottom of the housing 21. Unlike the prior art in which the pressure release structure 23 is welded to the cap 211, in the present application the pressure release structure 23 and the housing 21 are integrally molded, thereby avoiding leakage due to welding defects. Furthermore, the pressure release structure 23 and the housing 21 are integrally molded, which increases the strength of the pressure release structure 23 and improves its ability to withstand external impacts. Furthermore, the electrolyte in the housing 21 can cause creep or impacts on the pressure release structure 23. However, by integrally molding the pressure release structure 23 and the housing 21, the rigidity of the pressure release structure 23 is improved, which makes the pressure release structure 23 more resistant to creep and impacts caused by the electrolyte, thereby contributing to extending the life of the pressure release structure 23 and reducing the risk of leakage from the pressure release structure 23.

[0110] Referring to Figures 3, 4, 5, 6, 7 and 8, in some embodiments, the pressure release structure 23 is provided in a portion of the housing 21 below a mid-vertical plane 24 perpendicular to the height direction of the housing 21.

[0111] 3, a mid-vertical plane 24 is indicated by a dotted line in FIG. 3. The mid-vertical plane 24 is perpendicular to the height direction of the housing 21. In the height direction of the housing 21, the portion of the housing 21 above the mid-vertical plane 24 accounts for 50% of the height of the housing 21, and the portion of the housing 21 below the mid-vertical plane 24 accounts for 50% of the height of the housing 21. A pressure release structure 23 is provided in the portion below the mid-vertical plane 24.

[0112] The pressure from the electrolyte is relatively large in the height direction of the housing 21 below the mid-vertical surface 24, making it more likely for leakage to occur in the pressure release structure 23. In the present application, the pressure release structure 23 is provided in the height direction of the housing 21 below the mid-vertical surface 24, but by integrally molding the pressure release structure 23 with the housing 21, the strength and rigidity of the pressure release structure 23 are improved, the ability of the pressure release structure 23 to withstand impact and creep phenomena is improved, and the risk of leakage from the pressure release structure 23 can be reduced.

[0113] Referring to Figures 3, 4, 5, 6, 7 and 8, in some embodiments, the housing 21 has a wall 213 that supports the electrode assembly 22 in the direction of gravity, and the pressure release structure 23 is provided on the wall 213 and is integrally molded with the wall 213.

[0114] The wall 213 is a portion of the housing 21 that supports the electrode assembly 22 in the direction of gravity. In other words, the wall 213 is the bottom wall of the housing 21. The wall 213 may be one wall of the housing body 212, or may be the cap 211. When the wall 213 is the cap 211, it corresponds to a situation where the battery cell 20 is used upside down.

[0115] The wall 213 supports the electrode assembly 22 in the direction of gravity, and the pressure of the electrolyte against the wall 213 is greatest. If leakage occurs in the pressure release structure 23, the outflow rate and amount of electrolyte will be relatively large. In the present application, the pressure release structure 23 is integrally formed with the wall 213, which supports the electrode assembly 22, thereby improving the strength and rigidity of the pressure release structure 23, improving the ability of the pressure release structure 23 to withstand impact and creep, and reducing the risk of leakage from the pressure release structure 23.

[0116] In some other embodiments, the housing 21 has a wall portion 213 and a peripheral wall, the wall portion 213 supports the electrode assembly 22 in the direction of gravity, and the peripheral wall is provided along the outer periphery of the wall portion 213. The pressure release structure 23 is provided on the peripheral wall and is integrally molded with the peripheral wall.

[0117] 3 , 4 , 5 , 6 , 7 , and 8 , in some embodiments, the housing 21 includes a wall 213, and the pressure release structure 23 is provided in the wall 213. The wall 213 has an open area 23121. The wall 213 has a first surface 2131 and a second surface 2132 that face each other in the thickness direction of the wall 213. The pressure release structure 23 includes a score groove 232 that is recessed in a direction from the first surface 2131 to the second surface 2132. The score groove 232 is provided along the periphery of the open area 23121, and the open area 23121 is configured to be openable with the score groove 232 as a boundary.

[0118] In FIG. 8, the thickness direction is the direction indicated by K in the drawing.

[0119] The first surface 2131 and the second surface 2132 of the wall portion 213 are two opposing surfaces of the wall portion 213 in the thickness direction thereof, and the distance between the first surface 2131 and the second surface 2132 is the thickness of the wall portion 213. In an example where the wall portion 213 is a cap 211, the first surface 2131 is the outer surface of the cap 211 facing the outside of the battery cell 20, and the second surface 2132 is the inner surface of the cap 211 facing the inside of the battery cell 20.

[0120] Score grooves 232 are provided in the wall portion 213. The score grooves 232 may be grooves of various shapes, such as an arc shape, an H-shape, a U-shape, or an annular shape. The score grooves 232 in the wall portion 213 can be processed or formed by various methods, such as press forming and cold heading forming. In an example where the score grooves 232 are formed by press forming, the score grooves 232 are formed by press forming the wall portion 213 along the direction from the first surface 2131 to the second surface 2132, for example.

[0121] The open area 23121 is a pressure release area in the wall portion 213, and when the pressure or temperature inside the battery cell 20 reaches the release pressure, the open area 23121 opens using the score groove 232 as a boundary to release the pressure. The open area 23121 may be opened by separation or by rotation. The score groove 232 is provided along the periphery of the open area 23121.

[0122] Furthermore, when forming the score grooves 232, methods such as pressing or cold heading can be used, which causes the groove walls of the score grooves 232 to undergo cold work hardening (changing the arrangement of crystal grains, causing crystal lattice distortion, reducing the plasticity of the metal, and increasing the hardness of the material), improving their ability to withstand external impacts and making them less likely to be broken by external impacts. This therefore contributes to reducing the risk of liquid leakage from the pressure release structure 23.

[0123] 3, 4, 5, 6, 7 and 8, in some embodiments, the pressure release structure 23 includes at least one step of cut groove 231, and the at least one step of cut groove 231 is provided in the wall portion 213 in order along the direction from the first surface 2131 to the second surface 2132. The cut groove 231 of the step farthest from the first surface 2131 has an open area 23121 in the first groove bottom wall 2312.

[0124] The wall portion 213 may be provided with a single-stage cut groove 231, or may be provided with multiple stages of cut grooves 231. When the wall portion 213 is provided with multiple stages of cut grooves 231, the multiple stages of cut grooves 231 are provided in the wall portion 213 sequentially along the direction from the first surface 2131 to the second surface 2132, and the contour of the bottom surface of the cut grooves 231 of each stage becomes smaller in order of stage. The cut grooves 231 may have various shapes, such as a rectangle or a circle. The cut grooves 231 in the wall portion 213 can be processed or formed by various methods, such as press forming or cold heading forming.

[0125] For example, as shown in Figure 8, a score groove 232 and two-stage cut grooves 231 are provided in the wall portion 213, and both the score groove 232 and the cut groove 231 are press-formed, with the first-stage cut groove 231 being press-formed first on the first surface 2131, then the second-stage cut groove 231 being press-formed on the bottom surface of the first-stage cut groove 231, and then the score groove 232 being press-formed on the bottom surface of the second-stage cut groove 231.

[0126] At least one stage of cut grooves 231 and score grooves 232 are formed in the wall portion 213 in order along the direction from the first surface 2131 to the second surface 2132, and when forming, all of the cut grooves 231 are formed in the wall portion 213 first along the direction from the first surface 2131 to the second surface 2132, and then the score grooves 232 are formed. The score groove 232 is formed in the bottom surface of the cut groove 231 in the stage farthest from the first surface 2131. When only one stage of cut grooves 231 is formed in the wall portion 213, the cut groove 231 in that stage is the cut groove 231 in the stage closest to the first surface 2131 and also the cut groove 231 in the stage farthest from the first surface 2131.

[0127] A first groove bottom wall 2312 of the cut groove 231 of the step farthest from the first surface 2131 is a portion of the wall 213 that is lower than the bottom surface of the cut groove 231 of the step farthest from the first surface 2131, and after forming the cut groove 231 of the step farthest from the first surface 2131 in the wall 213, the remaining portion of the area of the wall 213 where the cut groove 231 of the step is to be provided becomes the first groove bottom wall 2312 of the cut groove 231 of the step farthest from the first surface 2131. As shown in FIG. 8 , in an example in which two steps of cut grooves 231 are provided in the wall 213, a portion of the wall 213 that is lower than the bottom surface of the cut groove 231 of the second step is the first groove bottom wall 2312 of the cut groove 231 of the step farthest from the first surface 2131.

[0128] An open area 23121 is formed in the first groove bottom wall 2312 of the cut groove 231 of the step furthest from the first surface 2131 .

[0129] At least one stage of cut grooves 231 and score grooves 232 is formed in wall 213 in sequence from first surface 2131 to second surface 2132. By forming cut grooves 231 and score grooves 232 in sequence in the order of the stages during forming, the forming force applied to wall 213 is reduced, the risk of cracks occurring in wall 213 is reduced, and cracks at the positions of score grooves 232 causing the pressure release structure 23 to malfunction is less likely to occur, improving the long-term reliability of the pressure release device. When forming at least one stage of cut grooves 231 and score grooves 232, methods such as pressing or cold heading can be used. In this way, cold work hardening occurs in the groove walls of cut grooves 231 and score grooves 232 (changing the arrangement of crystal grains, causing crystal lattice distortion, reducing the plasticity of the metal, and increasing the hardness of the material), improving the ability to withstand external impacts and making the material less susceptible to destruction by external impacts. This contributes to reducing the risk of liquid leakage from the pressure release structure 23.

[0130] The score grooves 232 are provided along the periphery of the open area 23121, and the open area 23121 can be opened using the score grooves 232 as boundaries, thereby increasing the pressure release area of the wall portion 213 and increasing the pressure release speed of the wall portion 213. In addition, the cut groove 231 has the open area 23121 in the first groove bottom wall 2312 of the step farthest from the first surface 2131, so that the cut groove 231 can provide an escape space for the open area 23121 to open, and even if the first surface 2131 is blocked by an obstacle, the open area 23121 can still open to release pressure.

[0131] Referring to Figures 3, 4, 5, 6, 7 and 8, in some embodiments, the pressure release structure 23 includes two-stage cut grooves 231, which are arranged in sequence along the direction from the first surface 2131 to the second surface 2132, with one stage of cut grooves 231 being arranged on the first surface 2131, the other stage of cut grooves 231 being arranged on the bottom surface of the one stage of cut grooves 231, and the score grooves 232 being arranged on the bottom surface of the other stage of cut grooves 231.

[0132] When a two-stage cut groove 231 is provided, the molding steps are relatively few and molding is relatively simple. In addition, due to cold work hardening, the rigidity, strength and hardness of the wall surface of the score groove 232 are effectively improved, and the risk of liquid leakage from the pressure release structure 23 can be effectively reduced, contributing to improved production efficiency and reduced production costs.

[0133] In some embodiments, the pressure release structure 23 includes multiple stages of score grooves 232, and the multiple stages of score grooves 232 are provided in order along the direction from the first surface 2131 to the second surface 2132. Of two adjacent stages of score grooves 232, the score groove 232 of the stage farther from the first surface 2131 is provided on the bottom surface of the score groove 232 of the stage closer to the first surface 2131.

[0134] When the cut grooves 231 are provided in the wall portion 213 , the score groove 232 of the step closest to the first surface 2131 is provided in the bottom surface of the cut groove 231 of the step farthest from the first surface 2131 .

[0135] When the wall portion 213 is provided with the cut grooves 231, the wall portion 213 may be provided with score grooves 232 with two, three, four, five, or the like stages. In an example in which two rows of score grooves 232 and two rows of cut grooves 231 are provided in the wall portion 213, the first row of cut grooves 231 (the cut groove 231 in the outermost row) is provided in the first surface 2131, the second row of cut grooves 231 (the cut groove 231 in the row farthest from the first surface 2131) is provided on the bottom surface of the first row of cut grooves 231, the first row of score grooves 232 (the score groove 232 in the row closest to the first surface 2131) is provided on the bottom surface of the second row of cut grooves 231, and the second row of score grooves 232 (the score groove 232 in the row farthest from the first surface 2131) is provided on the bottom surface of the first row of score grooves 232.

[0136] When the wall portion 213 is provided with a plurality of stages of score grooves 232, the shapes of the score grooves 232 of each stage are made to be substantially the same, and the score grooves 232 of each stage are provided along the periphery of the open area 23121.

[0137] If the multiple stages of score grooves 232 are provided in order from the first surface 2131 to the second surface 2132, the forming depth of each stage of score grooves 232 can be reduced, the forming force applied to the wall portion 213 when forming each stage of score grooves 232 can be reduced, and the risk of cracks occurring in the wall portion 213 can be reduced. In the process of processing the multiple stages of score grooves 232 in order from the first surface 2131 to the second surface 2132, the hardness of the remaining portion of the region of the wall portion 213 where the score grooves 232 are provided increases accordingly in accordance with the number of stages of processing the score grooves 232. This improves the hardness of the portion remaining after the multiple stages of score grooves 232 are provided in the wall portion 213, further improving long-term reliability and the ability to withstand impact, and reducing the probability of breakage when subjected to an impact from an external force.

[0138] 6, 7 and 8, in some embodiments, the surface of the open area 23121 away from the first surface 2131 and the second surface 2132 are aligned in the thickness direction.

[0139] "In the thickness direction, the surface of the open area 23121 away from the first surface 2131 is aligned with the second surface 2132" can be understood to mean that the open area 23121 does not protrude relative to the second surface 2132 in the thickness direction.

[0140] By designing the surface of the open area 23121 that is away from the first surface 2131 in the thickness direction to be aligned with the second surface 2132, the space occupied by the open area 23121 inside the battery cell 20 or battery 100 is reduced, which contributes to improving the energy density of the battery 100.

[0141] 9, 10, and 11, Fig. 9 is a schematic plan view of wall portion 213 according to some other embodiments of the present application, Fig. 10 is a cross-sectional view of portion LL in Fig. 9, and Fig. 11 is an enlarged view of portion M in Fig. 10. In some other embodiments, a part of wall portion 213 protrudes from second surface 2132 in a direction away from first surface 2131 to form reinforcing portion 2133. Reinforcing portion 2133 is provided on the outer periphery of open region 23121 so as to surround open region 23121.

[0142] The reinforcing portion 2133 has a ring-shaped structure that protrudes from the second surface 2132. The reinforcing portion 2133 is a protrusion formed by causing a part of the wall portion 213 to protrude from the first surface 2131 toward the second surface 2132 when the cut grooves 231 are formed in the wall portion 213 by pressing, and protruding from the second surface 2132. The cut grooves 231 of the step farthest from the first surface 2131 are located within the reinforcing portion 2133; in other words, the bottom surface of the cut grooves 231 of the step farthest from the first surface 2131 is farther from the first surface 2131 than the second surface 2132, and the reinforcing portion 2133 is provided to surround the cut grooves 231 of the step farthest from the first surface 2131.

[0143] A portion of the wall portion 213 protrudes from the second surface 2132 in a direction away from the first surface 2131 to form a reinforcing portion 2133, so that when the wall portion 213 is deformed, the reinforcing portion 2133 can reduce the effect of the deformation on the score groove 232, thereby reducing the risk of liquid leakage from the pressure release structure 23.

[0144] In some embodiments, the surface of the open area 23121 facing away from the first surface 2131 and the surface of the reinforcement portion 2133 facing away from the first surface 2131 are aligned in the thickness direction.

[0145] The phrase "the face of the open region 23121 away from the first surface 2131 and the face of the reinforcement portion 2133 away from the first surface 2131 are aligned in the thickness direction" means that the distance between the face of the open region 23121 away from the first surface 2131 and the first surface 2131 is equal to the distance between the face of the reinforcement portion 2133 away from the first surface 2131 and the first surface 2131 in the thickness direction. The open region 23121 does not protrude beyond the face of the reinforcement portion 2133 away from the first surface 2131.

[0146] In the thickness direction, the open area 23121 does not protrude toward the surface of the reinforcing portion 2133 that is away from the first surface 2131, thereby reducing the space occupied by the open area 23121 inside the battery cell 20 or the battery 100, which contributes to improving the energy density of the battery 100.

[0147] 9, 10 and 11, in some embodiments, the height of the reinforcing portion 2133 projecting from the second surface 2132 in the thickness direction is A, and A satisfies 0.5 mm≦A≦4 mm.

[0148] In the thickness direction, the height of the reinforcing portion 2133 projecting from the second surface 2132 is the distance between the surface of the reinforcing portion 2133 that is farther from the first surface 2131 and the second surface 2132 .

[0149] In the thickness direction, the height A of the reinforcing portion 2133 protruding from the second surface 2132 is 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm, 4 mm, etc.

[0150] If the height of the reinforcing portion 2133 protruding from the second surface 2132 in the thickness direction is kept within the range of 0.5 to 4 mm, the reinforcing effect of the reinforcing portion 2133 is improved and it does not occupy a large amount of the internal space of the battery cell 20 or the battery 100, thereby ensuring a higher energy density of the battery 100. When A<0.5 mm, the height of the reinforcing portion 2133 protruding from the second surface 2132 in the thickness direction is relatively small, and the reinforcing effect is not significant. When A>4 mm, the height of the reinforcing portion 2133 protruding from the second surface 2132 in the thickness direction is relatively large, and it occupies a relatively large amount of space, which affects the energy density of the battery 100.

[0151] In some embodiments, 1 mm≦A≦2.5 mm.

[0152] In the thickness direction, the height A of the reinforcing portion 2133 protruding from the second surface 2132 is 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, etc.

[0153] If the height of the reinforcing portion 2133 projecting from the second surface 2132 in the thickness direction is kept within the range of 1 to 2.5 mm, the reinforcing effect of the reinforcing portion 2133 is improved, and the space it occupies inside the battery cell 20 or battery 100 becomes relatively small.

[0154] 12, 13, 14, 15, and 16, Fig. 12 is a schematic plan view of a wall portion 213 according to some other embodiments of the present application, Fig. 13 is a cross-sectional view of a portion NN in Fig. 12, Fig. 14 is an enlarged view of a portion Q in Fig. 13, Fig. 15 is a cross-sectional view of a portion PP in Fig. 12, and Fig. 16 is an enlarged view of a portion R in Fig. 15. In some embodiments, the open region 23121 is curved along the thickness direction.

[0155] In some embodiments, the open region 23121 includes a flat region 23121b and a connecting region 23121c, and there is a height difference between the flat region 23121b and the open end of the score groove 232 in the thickness direction, and the connecting region 23121c connects the groove wall of the score groove 232 and the flat region 23121b. Optionally, the flat region 23121b is located in the middle of the open region 23121, and the connecting region 23121c is provided around the flat region 23121b and surrounds it. The cross section of the connecting region 23121c extends in an arc shape, and the open region 23121 is provided curved along the thickness direction.

[0156] In some other embodiments, the open area 23121 is an arched structure.

[0157] By designing the open region 23121 to bend in the thickness direction, when the wall portion 213 receives an external impact, the wall portion 213 can deform in the bending direction, absorbing the energy of the external impact and reducing the impact on the location of the score groove 232, thereby preventing damage to the location of the score groove 232 due to the external impact to some extent. Furthermore, the curved open region 23121 serves as a stress concentration area during pressure release, allowing the first groove bottom wall 2312 to more easily open at the location of the score groove 232. For the same release pressure, the depth of the score groove 232 can be made shallower, and the thickness of the first groove bottom wall 2312 at the location of the score groove 232 can be made greater. This makes it less likely that the first groove bottom wall 2312 will open at the location of the score groove 232 due to external influence, thereby reducing the risk of liquid leakage from the pressure release structure 23.

[0158] 12, 13, 14, 15 and 16, in some embodiments, the open area 23121 is curved along the direction from the second surface 2132 to the first surface 2131.

[0159] The open region 23121 is curved in the direction from the second surface 2132 to the first surface 2131, so that the open region 23121 does not extend beyond the surface of the reinforcing portion 2133 that is away from the first surface 2131 in the thickness direction. In other words, the open region 23121 curves in the direction from the second surface 2132 to the first surface 2131, and as a result, the bottom surface of the cut groove 231 forms a protrusion in the direction from the second surface 2132 to the first surface 2131.

[0160] In an embodiment in which the open region 23121 includes a flat region 23121b and a connecting region 23121c, the flat region 23121b is located on the side of the score groove 232 along the direction from the second surface 2132 toward the first surface 2131.

[0161] In an embodiment in which the open area 23121 is an arched structure, the arch apex of the open area 23121 is located on the side of the score groove 232 along the direction from the second surface 2132 toward the first surface 2131 .

[0162] When the open region 23121 bends in the direction from the second surface 2132 to the first surface 2131, gas inside the battery cell 20 acts on the open region 23121, generating a tensile force at the location of the score groove 232 on the first groove bottom wall 2312, allowing the first groove bottom wall 2312 to easily open at the location of the score groove 232. For the same release pressure, the depth of the score groove 232 can be made shallower and the thickness of the first groove bottom wall 2312 at the location of the score groove 232 can be made greater, making it less likely that the first groove bottom wall 2312 will open at the location of the score groove 232 due to external influences, thereby reducing the risk of leakage from the pressure release structure 23. When the electrolyte acts on the open region 23121, the acting force is relatively small, generating a tensile force at the location of the score groove 232 on the first groove bottom wall 2312, but not enough to open the score groove 232. In addition, a tensile force is generated at the location of the score groove 232 on the first groove bottom wall 2312, which distributes the force of the electrolyte, reduces the amplitude of the open area 23121, and prevents the pressure release structure 23 from easily opening due to the action of the electrolyte, thereby reducing the risk of liquid leakage from the pressure release structure 23.

[0163] 12 , 13 , 14 , 15 and 16 , in some embodiments, the pressure release structure 23 includes at least one stage of cut grooves 231, which are provided in the wall portion 213 in order along the direction from the first surface 2131 to the second surface 2132, and which has an open region 23121 in a first groove bottom wall 2312 of the cut groove 231 of the stage farthest from the first surface 2131. The first groove bottom wall 2312 includes a main body region 23122, which is provided surrounding the open region 23121, and the score groove 232 is provided between the open region 23121 and the main body region 23122. In the thickness direction, the main body region 23122 has a third surface 23122a and a fourth surface 23122b, and the distance between the third surface 23122a and the fourth surface 23122b is B. The open region 23121 has a fifth surface 23121a separated from the second surface 2132, and the third surface 23122a and the fifth surface 23121a are located on the same side of the first groove bottom wall 2312. The maximum distance between the third surface 23122a and the fifth surface 23121a is C, which satisfies B / 10≦C≦B.

[0164] When the battery cell 20 releases pressure, the portion of the first groove bottom wall 2312 where the open region 23121 is located opens, and the position of the main body region 23122 does not change. The main body region 23122 has a third surface 23122a and a fourth surface 23122b in the thickness direction, with the third surface 23122a being closer to the first surface 2131 in the thickness direction and the fourth surface 23122b being farther from the first surface 2131 in the thickness direction.

[0165] B is the distance between the third surface 23122a and the fourth surface 23122b in the thickness direction, that is, the thickness of the main body region 23122.

[0166] The open area 23121 has a fifth surface 23121a facing the first surface 2131, and the third surface 23122a and the fifth surface 23121a are located on the same side in the thickness direction of the first groove bottom wall 2312.

[0167] C is the maximum distance between the third surface 23122a and the fifth surface 23121a in the thickness direction.

[0168] The distance between the third surface 23122a and the fourth surface 23122b in the thickness direction is 1 to 10 times the maximum distance between the third surface 23122a and the fifth surface 23121a in the thickness direction, and this represents the degree of bending of the open area 23121. If C>B, the degree of bending of the open area 23121 becomes excessive, and the first groove bottom wall 2312 is likely to crack at the location of the score groove 232 due to the action of external impact. C

[0169] In some embodiments, the first surface 2131 is the outer surface of the wall 213 .

[0170] The phrase "the first surface 2131 is the outer surface of the wall portion 213" means that the first surface 2131 is the surface of the wall portion 213 that faces away from the electrode assembly 22. In contrast, if the second surface 2132 is the inner surface of the wall portion 213, the second surface 2132 is the surface that faces the electrode assembly 22.

[0171] When the first surface 2131 is the outer surface of the wall portion 213, the position of the first groove bottom wall 2312 is away from the first surface 2131 in the thickness direction. In this way, the score groove 232 provided in the first groove bottom wall 2312 is less susceptible to the action of external impact, and the pressure release structure 23 is less likely to be opened by external impact, thereby reducing the risk of liquid leakage from the pressure release structure 23.

[0172] ​In some embodiments, the pressure release structure 23 includes at least one step of cut groove 231, and the at least one step of cut groove 231 is provided in the wall 213 in order along the direction from the first surface 2131 to the second surface 2132, and has an open area 23121 in a first groove bottom wall 2312 of the cut groove 231 of the step farthest from the first surface 2131. The strength of the wall 213 is D1, the strength of the second groove bottom wall 2311 of the cut groove 231 of the step closest to the first surface 2131 is D2, and the strength of the first groove bottom wall 2312 at the location where the score groove 232 is located is D3, satisfying D3 > D2 ≥ D1. And / or, the hardness of the wall portion 213 is E1, the hardness of the second groove bottom wall 2311 is E2, and the hardness of the first groove bottom wall 2312 at the location of the score groove 232 is E3, where E3 > E2 ≧ E1 is satisfied. And / or, the stiffness of the wall portion 213 is F1, the stiffness of the second groove bottom wall 2311 is F2, and the stiffness of the first groove bottom wall 2312 at the location of the score groove 232 is F3, where F3 > F2 ≧ F1 is satisfied.

[0173] When only one stage of the cut grooves 231 is provided in the wall portion 213, the cut groove 231 in the stage closest to the first surface 2131 is also the cut groove 231 in the stage farthest from the first surface 2131. In other words, the first groove bottom wall 2312 and the second groove bottom wall 2311 are the same groove bottom wall. When two or more stages of the cut grooves 231 are provided in the wall portion 213, the first groove bottom wall 2312 and the second groove bottom wall 2311 are different groove bottom walls.

[0174] The strength and / or hardness and / or rigidity of the first groove bottom wall 2312 at the location of the score groove 232 is greater than the strength and / or hardness and / or rigidity of the second groove bottom wall 2311. The strength and / or hardness and / or rigidity of the second groove bottom wall 2311 is equal to or greater than the strength and / or hardness and / or rigidity of the wall portion 213.

[0175] When the strength of the second groove bottom wall 2311 is greater than the strength of the wall portion 213, it is equivalent to providing a reinforcing component around the score groove 232. When the wall portion 213 receives an external impact, the risk of the first groove bottom wall 2312 being damaged at the location where the score groove 232 is located is reduced, and the ability of the pressure relief structure 23 to withstand external impacts is further improved. Also, the strength of the first groove bottom wall 2312 at the location where the score groove 232 is located is relatively high, but its hardness is also relatively high, the ductility of the material decreases (the material becomes brittle), and it can be easily opened by the action of the internal gas. Therefore, when the release pressure is the same, the thickness of the first groove bottom wall 2312 at the location where the score groove 232 is located is thicker, the ability to withstand external impacts is increased, and the long-term reliability of the pressure relief structure 23 is further improved. When forming the cut groove 231 and the score groove 232, methods such as pressing or cold forging can be adopted. In this way, the phenomenon of cold working hardening occurs on the groove walls of the cut groove 231 and the score groove 232, and the strength, rigidity, and hardness of the second groove bottom wall 2311 and the first groove bottom wall 2312 at the location where the score groove 232 is located are improved.

[0176] In some embodiments, 1.2E≤E2≤2.5E is satisfied.

[0177] The ratio E2 / E1 of the hardness of the second groove bottom wall 2311 to the hardness of the wall portion 213 is 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, etc.

[0178] The hardness of the second groove bottom wall 2311 is 1.2 to 2.5 times the hardness of the wall portion 213. In this way, the second groove bottom wall 2311 can stop an external object, and the risk that the external object acts on the location of the score groove 232 can be reduced.

[0179] In some embodiments, 2.5E1 < E3≤5E1 is satisfied.

[0180] The ratio E3 / E1 of the hardness of the portion of the first groove bottom wall 2312 where the score groove 232 is located to the hardness of the wall portion 213 is 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, etc.

[0181] The hardness of the portion of the first groove bottom wall 2312 where the score groove 232 is located is 2.5 to 5 (excluding 2.5) times the hardness of the wall portion 213, so that the portion of the first groove bottom wall 2312 where the score groove 232 is located is relatively fragile and can be easily opened by the action of the internal air pressure.

[0182] In some embodiments, 5HBW≦E1≦150HBW.

[0183] E1 can be any value of 5HBW, 8HBW, 9HBW, 9.5HBW, 10HBW, 12HBW, 13HBW, 15HBW, 16HBW, 19HBW, 20HBW, 30HBW, 40HBW, 50HBW, 52HBW, 52.5HBW, 53HBW, 60HBW, 70HBW, 80HBW, 90HBW, 100HBW, 110HBW, 120HBW, 130HBW, 140HBW, 150HBW, or a range consisting of any two of these values.

[0184] If the strength of the wall portion 213 is 5 to 150 HBW, the wall portion 213 has the ability to withstand a relatively large impact, and has relatively excellent resistance to external impact.

[0185] In some embodiments, 5HBW≦E3≦200HBW.

[0186] E3 can be any value of 5HBW, 6HBW, 8HBW, 10HBW, 15HBW, 19HBW, 20HBW, 22.8HBW, 30HBW, 32HBW, 40HBW, 50HBW, 60HBW, 70HBW, 80HBW, 90HBW, 100HBW, 110HBW, 120HBW, 130HBW, 140HBW, 150HBW, 160HBW, 170HBW, 180HBW, 190HBW, 200HBW, or a range consisting of any two of these values.

[0187] If the strength of the portion of the first groove bottom wall 2312 where the score groove 232 is located is 5 to 2000 HBW, even if the wall portion 213 receives an external impact, the portion of the first groove bottom wall 2312 where the score groove 232 is located is less likely to break, and the pressure release structure 23 will have better ability to withstand external impacts.

[0188] In some embodiments, the first groove bottom wall 2312 has a minimum thickness W1 at the location of the score groove 232, which satisfies 5 HBW / mm≦E3 / W1≦10,000 HBW / mm, and preferably satisfies 190 HBW / mm≦E3 / W1≦4,000 HBW / mm.

[0189] E3 / W1 is 5HBW / mm, 6HBW / mm, 7HBW / mm, 20HBW / mm, 31HBW / mm, 32HBW / mm, 37.5HBW / mm, 42HBW / mm, 43HBW / mm, 5 0HBW / mm, 60HBW / mm, 61HBW / mm, 62HBW / mm, 63HBW / mm, 64HBW / mm, 75HBW / mm, 90HBW / mm, 100HBW / mm, 120HBW / mm, 150 HBW / mm, 190 HBW / mm, 500 HBW / mm, 1000 HBW / mm, 1200 HBW / mm, 1750 HBW / mm, 1800 HBW / mm, 2100 HBW / mm, 4000 HBW / mm, 5000 HBW / mm, 8000 HBW / mm, 9000 HBW / mm, 10000 HBW / mm, or a range consisting of any two of these values.

[0190] The hardness of the first groove bottom wall 2312 at the location of the score groove 232 is the Brinell hardness, and its unit is HBW. The Brinell hardness measurement method can be performed by referring to the measurement principle in GB / T 23.1-2018. In the actual measurement process, the hardness of the first groove bottom wall 2312 at the location of the score groove 232 can be obtained by measuring on two surfaces in the thickness direction. In an example where the wall portion 213 is the cap 211 of the battery cell 20, the hardness of the first groove bottom wall 2312 at the location of the score groove 232 may be measured on the surface away from the interior of the battery cell 20 at the location of the score groove 232, or the hardness of the first groove bottom wall 2312 at the location of the score groove 232 may be measured on the surface facing the interior of the battery cell 20 at the location of the score groove 232.

[0191] If E3 / W1 > 10,000 HBW / mm, the portion of the first groove bottom wall 2312 where the score groove 232 is located will be relatively thin and relatively hard, and the portion of the first groove bottom wall 2312 where the score groove 232 is located will be very thin and brittle, making the portion of the first groove bottom wall 2312 where the score groove 232 is located prone to breakage under normal use conditions of the battery cell 20, resulting in a relatively short service life for the battery cell 20. If E3 / W1 < 5 HBW / mm, the portion of the first groove bottom wall 2312 where the score groove 232 is located will be relatively thick and relatively weak, and when the battery cell 20 experiences thermal runaway, the portion of the first groove bottom wall 2312 where the score groove 232 is located will be stretched and stretched, resulting in a relatively poor timeliness of pressure release.

[0192] Considering the effect on the performance of the housing 21 of the thickness of the portion of the first groove bottom wall 2312 where the score groove 232 is located, and also the effect on the performance of the housing 21 of the hardness of the portion of the first groove bottom wall 2312 where the score groove 232 is located, if 5HBW / mm≦E3 / W1≦10000HBW / mm is set, the portion of the first groove bottom wall 2312 where the score groove 232 is located will have sufficient strength under conditions of normal use of the battery cell 20 and will not be easily damaged by fatigue, thereby extending the service life of the battery cell 20. Furthermore, the housing 21 will be able to release pressure in a timely manner through the open area 23121 when the battery cell 20 experiences thermal runaway, reducing the risk of the battery cell 20 exploding and improving the safety of the battery cell 20.

[0193] In some embodiments, 190 HBW / mm≦E3 / W1≦4000 HBW / mm.

[0194] E3 / W1 can be any value of 190HBW / mm, 250HBW / mm, 280HBW / mm, 300HBW / mm, 350HBW / mm, 400HBW / mm, 450HBW / mm, 500HBW / mm, 600HBW / mm, 700HBW / mm, 875HBW / mm, 1000HBW / mm, 1200HBW / mm, 1500HBW / mm, 1750HBW / mm, 1800HBW / mm, 2000HBW / mm, 2100HBW / mm, 2500HBW / mm, 3000HBW / mm, 3500HBW / mm, 4000HBW / mm, or a range consisting of any two of these values.

[0195] According to 190 HBW / mm≦E3 / W1≦4000 HBW / mm, the overall performance of the housing 21 is further improved, and it is ensured that the open area 23121 can be opened in a timely manner when the battery cell 20 experiences thermal runaway, and that the portion of the first groove bottom wall 2312 where the score groove 232 is located has sufficient strength under normal use conditions of the battery cell 20. On the premise of ensuring the safety of the battery cell 20, it is possible to extend the service life of the battery cell 20.

[0196] 12, 13, 14, 15, and 16, in some embodiments, the minimum thickness of the wall portion 213 at the location of the score groove 232 is W1, and the minimum thickness of the wall portion 213 is W2, satisfying 0.05≦W1 / W2≦0.95.

[0197] W1 / W2 can be any value of 0.05, 0.06, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.8, 0.85, 0.9, 0.95, or a range consisting of any two of these values.

[0198] The score grooves 232 are formed in the wall portion 213 by press forming or cold heading, and if W1 / W2 is within the range of 0.05 to 0.95, the crystal grains in the portion of the wall portion 213 where the score grooves 232 are located can be refined, improving the mechanical properties of the material in the portion of the wall portion 213 where the score grooves 232 are located, and improving the toughness and fatigue strength of the portion of the wall portion 213 where the score grooves 232 are located, thereby reducing the risk of the portion of the wall portion 213 where the score grooves 232 are located being destroyed during normal use of the battery cell 20, extending the service life of the battery cell 20, and reducing the risk of the battery cell 20 exploding in the event of thermal runaway.

[0199] In some embodiments, 0.12≦W1 / W2≦0.8.

[0200] W1 / W2 can be any value of 0.12, 0.13, 0.14, 0.15, 0.17, 0.2, 0.22, 0.25, 0.27, 0.3, 0.32, 0.35, 0.37, 0.4, 0.42, 0.45, 0.47, 0.5, 0.52, 0.55, 0.57, 0.6, 0.62, 0.65, 0.66, 0.67, 0.7, 0.72, 0.75, 0.77, 0.8, or a range consisting of any two of these values.

[0201] If W1 / W2 is 0.12≦W1 / W2≦0.8, the overall performance of the wall 213 is further improved, ensuring that the portion of the wall 213 where the score groove 232 is located is destroyed in a timely manner when the battery cell 20 experiences thermal runaway, and ensuring that the portion of the wall 213 where the score groove 232 is located has sufficient strength when the battery cell 20 is in normal use.

[0202] In some embodiments, 0.2≦W1 / W2≦0.5.

[0203] W1 / W2 can be any value of 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, or a range consisting of any two of these values.

[0204] If W1 / W2 is 0.2≦W1 / W2≦0.5, the risk of the portion of the wall portion 213 where the score groove 232 is located being destroyed under normal use conditions of the battery cell 20 is further reduced, and the portion of the wall portion 213 where the score groove 232 is located is guaranteed to be destroyed in a timely manner when the battery cell 20 experiences thermal runaway, thereby improving the timeliness of pressure release.

[0205] In some embodiments, 0.02 mm≦W1≦1.6 mm.

[0206] W1 can be any value of 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.42mm, 1.43mm, 1.45mm, 1.47mm, 1.5mm, 1.55mm, 1.6mm, or a range of any two values.

[0207] If W1<0.02 mm, it becomes more difficult to form the score groove 232, and the portion of the wall portion 213 where the score groove 232 is located is easily damaged during the forming process. If W1>1.6 mm, it becomes more difficult for the portion of the wall portion 213 where the score groove 232 is located to be destroyed in the event of thermal runaway of the battery cell 20, and it is more likely that pressure will not be released in a timely manner.

[0208] Therefore, if W1 is within the range of 0.02 mm≦W1≦1.6 mm, it is possible to reduce the difficulty of forming the score grooves 232 and improve the timeliness of pressure release in the event of thermal runaway of the battery cell 20.

[0209] In some embodiments, 0.06 mm≦W1≦0.4 mm.

[0210] W1 can be any value of 0.06 mm, 0.07 mm, 0.08 mm, 0.1 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.24 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, or a range of any two values.

[0211] If W1 is set to 0.06 mm≦W1≦0.4 mm, the difficulty of forming the score groove 232 can be further reduced, and the timeliness of pressure release in the event of thermal runaway of the battery cell 20 can be improved.

[0212] In some embodiments, 1 mm≦W2≦5 mm.

[0213] W2 can be any value of 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, or a range of values consisting of any two of these values.

[0214] If W2>5 mm, the thickness of the wall 213 is relatively large, the amount of material used for the housing 21 increases, the weight of the housing 21 increases, and the cost efficiency decreases. If W2<1 mm, the thickness of the wall 213 is relatively small, and the ability of the housing 21 to withstand deformation decreases.

[0215] Therefore, by making W2 1 mm≦W2≦5 mm, the housing 21 is relatively economical and has a relatively improved ability to withstand deformation.

[0216] In some embodiments, 1.2 mm≦W2≦3.5 mm.

[0217] W2 can be any value from 1.2mm, 1.25mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, or a range of any two values.

[0218] If W2 is set to 1.2 mm≦W2≦3.5 mm, the housing 21 will be more economical and have better ability to withstand deformation.

[0219] Furthermore, the dimension satisfies 2 mm ≦ W2 ≦ 3 mm.

[0220] 12 , 13 , 14 , 15 , and 16 , in some embodiments, the pressure release structure 23 includes at least one stage of cut grooves 231, and the at least one stage of cut grooves 231 is provided in the wall 213 in order along the direction from the first surface 2131 to the second surface 2132, and has an open area 23121 in the first groove bottom wall 2312 of the cut groove 231 of the stage farthest from the first surface 2131. The average size of the crystal grains in the wall 213 is G1, the average size of the crystal grains in the second groove bottom wall 2311 of the cut groove 231 of the stage closest to the first surface 2131 is G2, and the average size of the crystal grains in the first groove bottom wall 2312 at the location where the score groove 232 is located is G3, satisfying G1>G2>G3.

[0221] The method for measuring the average crystal grain size can refer to the cutting method in GB 6394-2017, and a detailed description thereof will be omitted here. When measuring the average crystal grain size of the first groove bottom wall 2312 at the location of the score groove 232, the measurement can be made along the thickness direction of the first groove bottom wall 2312 at the location of the score groove 232, and when measuring the average crystal grain size of the wall portion 213, the measurement can be made along the thickness direction of the wall portion 213.

[0222] For ease of measurement, the number of crystal grains per unit area may be used. When expressed as the number of crystal grains per unit area, the number of crystal grains per unit area of the wall portion 213 is smaller than the number of crystal grains per unit area of the second groove bottom wall 2311, which is smaller than the number of crystal grains per unit area of the first groove bottom wall 2312 at the location of the score groove 232.

[0223] When forming the cut groove 231 and the score groove 232 using methods such as pressing or cold heading, the crystal grains of the material are broken down and refined, so that the average size of the crystal grains at the location of the score groove 232 on the first groove bottom wall 2312 is smaller than the average size of the crystal grains on the second groove bottom wall 2311, which in turn is smaller than the average size of the crystal grains on the wall portion 213.

[0224] In some embodiments, G3 / G1≦0.9.

[0225] G3 / G1 can be any value of 0.01, 0.03, 0.04, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or a range consisting of any two of these values.

[0226] If G3 / G1 is set to 0.9 or less, the difference between the average crystal grain size of the portion of the first groove bottom wall 2312 where the score grooves 232 are located and the average crystal grain size of the wall portion 213 is relatively large. By reducing the average crystal grain size of the portion of the first groove bottom wall 2312 where the score grooves 232 are located, the crystal grains of the portion of the first groove bottom wall 2312 where the score grooves 232 are located are refined, improving the mechanical properties of the material of the portion of the first groove bottom wall 2312 where the score grooves 232 are located, and further improving the toughness and fatigue strength of the portion of the first groove bottom wall 2312 where the score grooves 232 are located. This reduces the risk of the portion of the first groove bottom wall 2312 where the score grooves 232 are located being broken under normal use conditions of the battery cell 20, and prolongs the service life of the battery cell 20.

[0227] In some embodiments, G3 / G1≧0.05.

[0228] If G3 / G1<0.05, it becomes more difficult to form the cut groove 231 and the score groove 232, and the strength of the portion of the first groove bottom wall 2312 where the score groove 232 is located becomes excessive, making the portion of the first groove bottom wall 2312 where the score groove 232 is located less likely to be destroyed in the event of thermal runaway of the battery cell 20, making it more likely that pressure cannot be released in a timely manner.

[0229] Therefore, if G3 / G1 is set to 0.05 or more, the difficulty of forming the cut grooves 231 and the score grooves 232 can be reduced, and the timeliness of pressure release in the event of thermal runaway of the battery cell 20 can be improved.

[0230] In some embodiments, 0.1≦G3 / G1≦0.5.

[0231] G3 / G1 can be any value of 0.1, 0.12, 0.15, 0.17, 0.2, 0.22, 0.25, 0.27, 0.3, 0.32, 0.35, 0.37, 0.4, 0.42, 0.45, 0.47, 0.5, or a range consisting of any two of these values.

[0232] If G3 / G1 is set to 0.1≦G3 / G1≦0.5, the overall performance of the wall portion 213 is further improved, ensuring that the portion of the first groove bottom wall 2312 where the score groove 232 is located is destroyed in a timely manner in the event of thermal runaway of the battery cell 20, and ensuring that the portion of the first groove bottom wall 2312 where the score groove 232 is located has sufficient strength during normal use of the battery cell 20.

[0233] In some embodiments, 0.4 μm≦G3≦75 μm.

[0234] G3 can be any value of 0.4 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 10 μm, 15 μm, 16 μm, 20 μm, 25 μm, 28 μm, 30 μm, 35 μm, 36 μm, 40 μm, 45 μm, 47.5 μm, 48 μm, 49 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 72 μm, 75 μm, or a range consisting of any two of these values.

[0235] If G3 > 75 μm, the toughness and fatigue strength of the first groove bottom wall 2312 at the location of the score groove 232 will be relatively low. If G3 < 0.4 μm, it will be relatively difficult to form the notched grooves 231 and the score grooves 232, and the strength of the first groove bottom wall 2312 at the location of the score groove 232 will be excessively high, making it difficult for the location of the first groove bottom wall 2312 at the location of the score groove 232 to be destroyed in the event of thermal runaway of the battery cell 20, and making it more likely that pressure will not be released in a timely manner. Therefore, if 0.4 μm≦G3≦75 μm is satisfied, on the one hand, it is possible to reduce the difficulty of forming the cut grooves 231 and the score grooves 232 and improve the timeliness of pressure release during thermal runaway of the battery cell 20, and on the other hand, it is possible to improve the toughness and fatigue strength of the portion of the first groove bottom wall 2312 where the score groove 232 is located, and reduce the risk of the portion of the first groove bottom wall 2312 where the score groove 232 is located being destroyed under conditions of normal use of the battery cell 20.

[0236] In some embodiments, 1 μm≦G3≦10 μm.

[0237] G3 can be any value of 1 μm, 1.5 μm, 1.6 μm, 2 μm, 2.5 μm, 2.6 μm, 3 μm, 3.3 μm, 3.5 μm, 3.6 μm, 4 μm, 4.5 μm, 4.6 μm, 5 μm, 5.5 μm, 5.6 μm, 6 μm, 6.5 μm, 6.6 μm, 6.7 μm, 7 μm, 7.5 μm, 7.6 μm, 8 μm, 8.5 μm, 8.6 μm, 9 μm, 9.5 μm, 9.6 μm, 10 μm, or a range consisting of any two of these values.

[0238] If G3 is set to 1 μm≦G3≦10 μm, the overall performance of the wall portion 213 is further improved, ensuring that the portion of the first groove bottom wall 2312 where the score groove 232 is located is destroyed in a timely manner in the event of thermal runaway of the battery cell 20, and ensuring that the portion of the first groove bottom wall 2312 where the score groove 232 is located has sufficient strength under conditions of normal use of the battery cell 20.

[0239] In some embodiments, 10 μm≦G1≦150 μm is satisfied.

[0240] G1 can be any value of 10 μm, 13 μm, 14 μm, 15 μm, 20 μm, 25 μm, 30 μm, 32 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, or a range consisting of any two of these values.

[0241] In some embodiments, 30 μm≦G1≦100 μm is satisfied.

[0242] G1 can be any value of 30 μm, 32 μm, 35 μm, 37 μm, 40 μm, 42 μm, 45 μm, 47 μm, 50 μm, 52 μm, 55 μm, 57 μm, 60 μm, 62 μm, 65 μm, 67 μm, 70 μm, 72 μm, 75 μm, 77 μm, 80 μm, 82 μm, 85 μm, 87 μm, 90 μm, 92 μm, 95 μm, 97 μm, 100 μm, or a range consisting of any two of these values.

[0243] In some embodiments, the minimum thickness of the first groove bottom wall 2312 at the location of the score groove 232 is W1, and the average size of the crystal grains of the first groove bottom wall 2312 at the location of the score groove 232 is G3, satisfying 1≦W1 / G3≦100.

[0244] If W1 / G3<1, the fewer the number of crystal particle layers at the location of the score groove 232 on the first groove bottom wall 2312 in the thickness direction of the wall portion 213, the less fatigue strength there will be at the location of the score groove 232 on the first groove bottom wall 2312; if W1 / G3>100, the more the number of crystal particle layers at the location of the score groove 232 on the first groove bottom wall 2312 in the thickness direction, the more strength there will be at the location of the score groove 232 on the first groove bottom wall 2312, and there is a risk that the location of the score groove 232 on the first groove bottom wall 2312 will not be destroyed in a timely manner when the battery cell 20 experiences thermal runaway. Therefore, if 1≦W1 / G3≦100 is satisfied, on the one hand, the number of crystal grain layers in the thickness direction at the portion of the first groove bottom wall 2312 where the score groove 232 is located becomes relatively large, the fatigue strength of the portion of the first groove bottom wall 2312 where the score groove 232 is located increases, and the risk of the portion of the first groove bottom wall 2312 where the score groove 232 is located being destroyed under normal conditions of use of the battery cell 20 is reduced; on the other hand, the portion of the first groove bottom wall 2312 where the score groove 232 is located is destroyed in a more timely manner during thermal runaway of the battery cell 20, allowing pressure to be released in a timely manner.

[0245] In some embodiments, 5≦W1 / G3≦20.

[0246] W1 / G3 can be any value of 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.4, 8.5, 8.8, 8.9, 9, 9.5, 9.6, 10, 10.5, 11, 11.4, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, or a range of any two values.

[0247] If W1 / G3 is set to 5≦W1 / G3≦20, the overall performance of the wall portion 213 is further improved, ensuring that the portion of the first groove bottom wall 2312 where the score groove 232 is located is destroyed in a timely manner when the battery cell 20 experiences thermal runaway; and ensuring that the portion of the first groove bottom wall 2312 where the score groove 232 is located has sufficient fatigue strength under normal conditions of use of the battery cell 20, thereby extending the service life of the battery cell 20.

[0248] In some embodiments, the housing 21 includes a housing body 212 and a cap 211, the housing body 212 has an opening, and the cap 211 is connected to the housing body 212 to seal the opening. A pressure release structure 23 is provided on the cap 211.

[0249] The pressure release structure 23 is provided on the cap 211, and the cap 211 is located at the bottom of the housing body 212 to accommodate the scenario in which the battery cell 20 is used upside down.

[0250] In some embodiments, the housing 21 includes a housing body 212 and a cap 211, the housing body 212 has an opening, the cap 211 is connected to the housing body 212 to seal the opening, and the pressure release structure 23 is provided on the housing body 212.

[0251] The pressure relief structure 23 is provided on the housing body 212 , and the pressure relief structure 23 is located at the bottom of the housing body 212 .

[0252] In some embodiments, the housing body 212 has openings at both ends in the first direction, and the housing 21 includes two caps 211, which seal the openings in a one-to-one correspondence.

[0253] The features and performance of the present application are further illustrated below using examples.

[0254] In each example and comparative example, the battery cell 20 is a quadrilateral battery cell 20 with all four corners being right angles, the cap 211 of the battery cell 20 is the wall portion 213, the capacity of the battery cell 20 is 150 Ah, and the chemical system is NCM.

[0255] 1.Measurement method

[0256] (1) Measurement of the minimum thickness of the first groove bottom wall 2312 at the location of the score groove 232 and the wall portion 213

[0257] The wall 213 was cut into three parts, and the middle part was used as a sample. The cross sections at both ends of the sample were the location of the score groove 232 on the first groove bottom wall 2312 and a location where the notched groove 231 was not provided on the wall 213. The cutting direction was perpendicular to the length direction of the open area 23121. After polishing the cross section of the middle part to thoroughly remove burrs, the sample was placed in a coordinate measuring machine, and the thickness of the location of the score groove 232 on the first groove bottom wall 2312 and the wall 213 on the cross section was measured.

[0258] (2) Measurement of the average grain size of the first groove bottom wall 2312 at the location of the score groove 232 and the wall portion 213

[0259] The average grain size of the first groove bottom wall 2312, where the score grooves 232 were located, and the wall 213 was measured using electron backscatter diffraction (EBSD). The wall 213 was cut into the required number of sections, and the middle section was used as a sample. Cross sections at both ends of the sample were taken of the first groove bottom wall 2312, where the score grooves 232 were located, and of the wall 213, where the notched grooves 231 were not provided. The cutting direction was perpendicular to the length of the open area 23121. The cutting equipment did not alter the grain structure. The sample was then electropolished, fixed to a sample stage tilted at 70°, and an appropriate magnification was selected. EBSD scanning was performed using a scanning electron microscope (SEM) equipped with electron backscatter diffraction (EBSD) components. Based on the scan results, the average grain size (i.e., the circle-equivalent diameter of a complete grain within the detection plane) was calculated.

[0260] (3) Measurement of the hardness of the first groove bottom wall 2312 at the location of the score groove 232 and the wall portion 213

[0261] The wall 213 was cut into the required number of sections, and the middle section was used as a sample. The cross sections at both ends of the sample were the section of the first groove bottom wall 2312 where the score groove 232 was located and the section of the wall 213 where the notched groove 231 was not provided. The cutting direction was perpendicular to the length of the open region 23121. After the test section was polished to thoroughly remove burrs, the sample was placed horizontally on a Brinell hardness tester (with the cross-sectional direction of the sample parallel to the pressing direction of the hardness tester) and hardness measurement was performed. If the width of the section of the first groove bottom wall 2312 where the score groove 232 was located was less than 1 mm, or if the indenter size of the Brinell hardness tester was much larger than the width of the section of the first groove bottom wall 2312 where the score groove 232 was located, a non-standard indenter was machined to perform the hardness measurement in accordance with the principles of Brinell hardness measurement and conversion.

[0262] (4) The crack rate of the first groove bottom wall 2312 at the location of the score groove 232 under normal use conditions of the battery cell 20

[0263] The battery cells 20 were subjected to charge / discharge cycles at 5% to 97% SOC at 25±2°C while the air pressure of the gas generated inside the battery cells 20 was monitored, and 500 sets of tests were conducted. The test was stopped when the life of the battery cells 20 decreased to 80% SOH, or when a crack occurred in the first groove bottom wall 2312 at the location of the score groove 232 during the cycling process of any one of the battery cells 20. The condition for determining whether a crack occurred in the location of the score groove 232 in the first groove bottom wall 2312 was that the internal air pressure of the battery cell 20 had decreased by more than 10% of the maximum air pressure. The crack rate in the location of the score groove 232 in the first groove bottom wall 2312 was calculated as follows: Crack rate = Number of cranks / Total number × 100%

[0264] (5) Explosion rate when battery cell 20 goes into thermal runaway

[0265] A small heating film was placed inside the battery cell 20, and electricity was passed through the heating film to heat the battery cell 20 until the battery cell 20 went into thermal runaway, and the battery cell 20 was observed for explosion. 500 sets of tests were repeated, and the explosion rate of the battery cells 20 was calculated as follows: Explosion rate = Number of explosions / Total number × 100%

[0266] 2. Measurement results

[0267] For each example and comparative example, the measurement results of the minimum thickness W1 of the first groove bottom wall 2312 at the location of the score groove 232, the minimum thickness W2 of the wall portion 213, the average crystal grain size G3 of the first groove bottom wall 2312 at the location of the score groove 232, the average crystal grain size G1 of the wall portion 213, the hardness E3 of the first groove bottom wall 2312 at the location of the score groove 232, and the hardness E1 of the wall portion 213 are shown in Table 1. In Table 1, W1 and W2 are in mm, G3 and G1 are in mm, and E3 and E1 are in HBW. The crack rate Q1 of the location of the first groove bottom wall 2312 at the location of the score groove 232 under normal use conditions of the battery cell 20 and the explosion rate Q2 of the battery cell 20 during thermal runaway are shown in Table 2.

[0268] [Table 1]

[0269] [Table 2]

[0270] As can be seen from Tables 1 and 2, comparing Examples 1 to 8 with Comparative Example 1, when W1 / W2 > 0.95, the explosion rate of the battery cell 20 during thermal runaway was relatively high, exceeding 12%. As can be seen from comparing Examples 1 to 8 with Comparative Example 2, when W1 / W2 < 0.05, the crack rate of the first groove bottom wall 2312 at the location of the score groove 232 under normal use conditions of the battery cell 20 was relatively high, exceeding 12%. If W1 / W2 is set to 0.05 ≦ W1 / W2 ≦ 0.95, the risk of cracking of the first groove bottom wall 2312 at the location of the score groove 232 under normal use conditions of the battery cell 20 can be reduced, and pressure can be released in a timely manner by the location of the score groove 232 of the first groove bottom wall 2312 during thermal runaway of the battery cell 20, thereby reducing the risk of explosion of the battery cell 20. As can be seen from Examples 2 to 7, when W1 / W2 is 0.12≦W1 / W2≦0.8, the overall performance of the battery cell 20 is better, and the crack rate at the location of the score groove 232 on the first groove bottom wall 2312 under normal use conditions of the battery cell 20 and the explosion rate during thermal runaway of the battery cell 20 are relatively low. When W1 / W2 is 0.2≦W1 / W2≦0.5, the effect is even better.

[0271] As can be seen from Examples 10 to 15, when G3 / G1≦0.9, the crack rate was relatively low at the location of the score groove 232 on the first groove bottom wall 2312 under normal use conditions of the battery cell 20. In Example 9, when G3 / G1>0.9, the crack rate was significantly high at the location of the score groove 232 on the first groove bottom wall 2312 under normal use conditions of the battery cell 20. As can be seen from comparing Examples 10 to 15 with Example 9, setting G3 / G1 to 0.9 or less reduces the risk of the location of the score groove 232 on the first groove bottom wall 2312 being broken under normal use conditions of the battery cell 20, and can extend the service life of the battery cell 20.

[0272] As can be seen from Example 15, when G3 / G1<0.05, the portion of the first groove bottom wall 2312 where the score groove 232 is located becomes difficult to break when the battery cell 20 experiences thermal runaway, and pressure cannot be released in a timely manner, significantly increasing the risk of explosion of the battery cell 20. As can be seen from a comparison between Examples 9 to 14 and Example 15, if G3 / G1 is set to 0.5 or more, the explosion rate of the battery cell 20 when it experiences thermal runaway can be effectively reduced. When 0.1≦G3 / G1≦0.5, the crack rate at the portion of the first groove bottom wall 2312 where the score groove 232 is located under normal use conditions of the battery cell 20 and the explosion rate at the time of thermal runaway of the battery cell 20 are relatively low, which ensures that the portion of the first groove bottom wall 2312 where the score groove 232 is located will be destroyed in a timely manner when the battery cell 20 experiences thermal runaway, and that the portion of the first groove bottom wall 2312 where the score groove 232 is located will have sufficient strength under normal use conditions of the battery cell 20.

[0273] Comparing Examples 17 to 21 with Example 16, it can be seen that when 1≦W1 / G3≦100, the battery cell 20 was able to release pressure in a timely manner during thermal runaway, and the explosion rate of the battery cell 20 was relatively low. When 5≦W1 / G3≦20, the overall performance of the battery cell 20 was better, and the crack rate at the location of the score groove 232 on the first groove bottom wall 2312 under normal use conditions of the battery cell 20 and the explosion rate during thermal runaway of the battery cell 20 were relatively low.

[0274] A comparison of Examples 23 to 27 with Example 22 shows that when E3 / W1 > 10,000 HBW / mm, the crack rate at the location of the score groove 232 on the first groove bottom wall 2312 under normal use conditions of the battery cell 20 was relatively high. A comparison of Examples 23 to 27 with Example 28 shows that when E3 / W1 < 5 HBW / mm, the explosion rate at the time of thermal runaway of the battery cell 20 was relatively high. When 5 HBW / mm ≦ E3 / W1 ≦ 10,000 HBW / mm, the risk of cracking at the location of the score groove 232 on the first groove bottom wall 2312 under normal use conditions of the battery cell 20 can be reduced, and when thermal runaway of the battery cell 20 occurs, pressure can be released in a timely manner by the location of the score groove 232 on the first groove bottom wall 2312, thereby reducing the risk of explosion of the battery cell 20. As can be seen from Examples 24 and 25, when 190 HBW / mm≦E3 / W1≦4000 HBW / mm, the overall performance of the battery cell 20 was better, and the crack rate at the location of the score groove 232 on the first groove bottom wall 2312 under normal use conditions of the battery cell 20 and the explosion rate during thermal runaway of the battery cell 20 were relatively low.

[0275] As can be seen by comparing Examples 29 and 30 with Examples 31 and 32, when E3 / E1≦1, the crack rate at the location of the score groove 232 on the first groove bottom wall 2312 under normal use conditions of the battery cell 20 was relatively high. When E3 / E1>1, the crack rate at the location of the score groove 232 on the first groove bottom wall 2312 under normal use conditions of the battery cell 20 can be effectively reduced. As can be seen by comparing Example 30 and Example 29, when E3 / E1>5, the explosion rate of the battery cell 20 during thermal runaway was relatively high. When E3 / E1≦5, the risk of explosion of the battery cell 20 can be reduced.

[0276] An embodiment of the present application further provides a battery 100. The battery 100 includes the battery cell 20 described above.

[0277] An embodiment of the present application further provides an electric device, which includes the above-mentioned battery 100, and the battery 100 provides electric energy to the electric device.

[0278] Some embodiments of the present application will be described with reference to FIGS.

[0279] An embodiment of the present application provides a battery cell 20, which includes an electrode assembly 22, a housing 21, and a pressure release structure 23. The housing 21 accommodates the electrode assembly 22 and has a wall 213 that supports the electrode assembly 22 in the direction of gravity. The pressure release structure 23 is provided on the wall 213 and is integrally molded with the wall 213. When the battery cell 20 is in normal use, the pressure release structure 23 is located at the bottom of the housing 21. Unlike the prior art in which the pressure release structure 23 is welded to the cap 211, the pressure release structure 23 and the wall 213 are integrally molded in the present application, which prevents leakage due to welding defects. In addition, the pressure release structure 23 has an improved ability to withstand external impacts. Furthermore, the electrolyte in the housing 21 may cause creep or impact on the pressure release structure 23, but by integrally molding the pressure release structure 23 and the wall portion 213, the rigidity of the pressure release structure 23 can be improved, and therefore the ability of the pressure release structure 23 to withstand creep and impact caused by the electrolyte becomes relatively stronger, which contributes to extending the life of the pressure release structure 23 and reduces the risk of leakage from the pressure release structure 23.

[0280] The wall portion 213 has a first surface 2131 and a second surface 2132 that face each other in the thickness direction. The pressure release structure 23 includes a score groove 232 and at least one stage of cut grooves 231, and the at least one stage of cut grooves 231 and score grooves 232 are provided in order on the wall portion 213 along the direction from the first surface 2131 to the second surface 2132. An open region 23121 is provided on the first groove bottom wall 2312 of the cut groove 231 in the stage farthest from the first surface 2131. The score groove 232 is provided along the periphery of the open region 23121, and the open region 23121 is configured to be openable with the score groove 232 as a boundary. At least one stage of the notched grooves 231 and the score grooves 232 is formed in the wall 213 in order from the first surface 2131 to the second surface 2132. By forming the notched grooves 231 and the score grooves 232 in order according to the stages during molding, the molding force applied to the wall 213 is reduced, reducing the risk of cracks occurring in the wall 213. This reduces the likelihood of the pressure release structure 23 failing to function due to cracks occurring at the positions where the score grooves 232 are formed, thereby improving the long-term reliability of the pressure release device. Furthermore, the notched grooves 231 and the score grooves 232 can be formed using methods such as pressing or cold heading. This causes cold work hardening in the groove walls of the notched grooves 231 and the score grooves 232 (which changes the arrangement of crystal grains, causing crystal lattice distortion, reducing the plasticity of the metal, and increasing the hardness of the material), improving their ability to withstand external impacts and making them less susceptible to breakage due to external impacts. This contributes to reducing the risk of liquid leakage from the pressure release structure 23.

[0281] A part of wall portion 213 protrudes from second surface 2132 in a direction away from first surface 2131 and is formed as reinforcing portion 2133. Reinforcing portion 2133 is provided on the outer periphery of first groove bottom wall 2312 so as to surround first groove bottom wall 2312. By forming a part of wall portion 213 protruding from second surface 2132 in a direction away from first surface 2131 and as reinforcing portion 2133, when wall portion 213 deforms, reinforcing portion 2133 can reduce the effect of the deformation on score grooves 232, and therefore the risk of liquid leakage from pressure release structure 23 can be reduced.

[0282] The open area 23121 is curved in the direction from the second surface 2132 to the first surface 2131. When the open area 23121 is curved in the direction from the second surface 2132 to the first surface 2131, and gas inside the battery cell 20 acts on the open area 23121, a tensile force is generated at the location of the first groove bottom wall 2312 where the score groove 232 is located. This allows the first groove bottom wall 2312 to easily open at the location of the score groove 232. For the same release pressure, the depth of the score groove 232 can be made shallower and the thickness of the first groove bottom wall 2312 at the location of the score groove 232 can be made greater. This makes it less likely that the first groove bottom wall 2312 will open at the location of the score groove 232 due to external influences, thereby reducing the risk of liquid leakage from the pressure release structure 23. When the electrolyte acts on the open region 23121, the acting force is relatively small, and a tensile force is generated at the location of the first groove bottom wall 2312 where the score groove 232 is located, but this does not result in the opening of the score groove 232. Furthermore, the tensile force generated at the location of the first groove bottom wall 2312 where the score groove 232 is located disperses the acting force of the electrolyte, reducing the amplitude of the open region 23121. As a result, the pressure release structure 23 does not easily open due to the action of the electrolyte, the risk of leakage from the pressure release structure 23 can be reduced.

[0283] The above is only a preferred embodiment of the present application and does not limit the present application. Those skilled in the art may have various modifications and variations to the present application. As long as they do not deviate from the spirit and principle of the present application, any modifications, equivalent replacements, improvements, etc., fall within the scope of protection of the present application. [Explanation of symbols]

[0284] 10. Cabinet 11 First Part 12 Second Part 20 battery cells 21 Housing 211 Cap 212 Housing body 213 Wall section 2131 First Side 2132 Second Side 2133 Reinforcement 22 Electrode Assembly 23 Pressure release structure 231 Cutting groove 2311 Second groove bottom wall 2312 First groove bottom wall 23121 Open area 23121a The Fifth Face 23121b Flat area 23121c Connected area 23122 Body area 23122a Third Face 23122b Fourth Face 232 Score groove 24 Mid-vertical plane 100 batteries 200 control device 300 Engine 1000 vehicles

Claims

1. an electrode assembly; a housing that accommodates the electrode assembly; a pressure relief structure disposed on a lower portion of the housing and integrally molded with the housing; including a battery cell.

2. The battery cell according to claim 1 , wherein the pressure release structure is provided at a portion of the housing below a mid-vertical plane perpendicular to the height direction of the housing.

3. The battery cell according to claim 2 , wherein the housing has a wall portion that supports the electrode assembly in the direction of gravity, and the pressure release structure is provided on the wall portion and is integrally molded with the wall portion.

4. the housing includes a wall, the pressure relief structure is disposed on the wall, and the wall has an open area; the wall portion has a first surface and a second surface opposed to each other in a thickness direction thereof, 4. The battery cell according to claim 1, wherein the pressure release structure includes a score groove recessed in a direction from the first surface to the second surface, the score groove being provided along a periphery of the open area, and the open area being configured to be openable with the score groove as a boundary.

5. the pressure release structure includes at least one step of notched grooves, the at least one step of notched grooves being provided in the wall portion in a sequence along a direction from the first surface to the second surface, The battery cell according to claim 4 , wherein the open area is provided in a first groove bottom wall of the cut groove at a step furthest from the first surface.

6. 6. The battery cell of claim 5, wherein the pressure release structure includes two stages of the cut grooves, the two stages of the cut grooves being arranged in order along a direction from the first surface to the second surface, the cut grooves of one stage being arranged on the first surface, the cut grooves of the other stage being arranged on a bottom surface of the cut grooves of the one stage, and the score grooves being arranged on a bottom surface of the cut grooves of the other stage.

7. the pressure release structure includes a plurality of stages of the score grooves, the plurality of stages of the score grooves being provided in order along a direction from the first surface to the second surface, 7. The battery cell according to claim 4, wherein, of the score grooves in two adjacent rows, the score groove in the row farther from the first surface is provided on a bottom surface of the score groove in the row closest to the first surface.

8. The battery cell according to any one of claims 4 to 7, wherein a surface of the open region that is farther from the first surface and the second surface are aligned in the thickness direction.

9. a portion of the wall portion protruding from the second surface in a direction away from the first surface to form a reinforcing portion, The battery cell according to any one of claims 4 to 7, wherein the reinforcing portion is provided on the outer periphery of the open area so as to surround the open area.

10. The battery cell according to claim 9 , wherein a surface of the open region away from the first surface and a surface of the reinforcing portion away from the first surface are aligned in the thickness direction.

11. The battery cell according to claim 9 or 10, wherein a height A of the reinforcing portion projecting from the second surface in the thickness direction satisfies 0.5 mm≦A≦4 mm.

12. The battery cell according to claim 11 , wherein 1 mm≦A≦2.5 mm is satisfied.

13. The battery cell according to any one of claims 4 to 12, wherein the open area is curved along the thickness direction.

14. The battery cell according to claim 13 , wherein the open area is curved along a direction from the second surface to the first surface.

15. the pressure release structure includes at least one step of notched grooves, the at least one step of notched grooves being provided in the wall portion in order along a direction from the first surface to the second surface, and the opening area being provided in a first groove bottom wall of the notched groove in a step farthest from the first surface; the first groove bottom wall includes a body region, the body region is provided surrounding the open region, and the score groove is provided between the open region and the body region; 15. The battery cell of claim 13, wherein in the thickness direction, the main body region has a third surface and a fourth surface, a distance between the third surface and the fourth surface is B, the open region has a fifth surface spaced apart from the second surface, the third surface and the fifth surface are located on the same side of the first groove bottom wall, a maximum distance between the third surface and the fifth surface is C, and B / 10≦C≦B is satisfied.

16. The battery cell according to any one of claims 4 to 15, wherein the first surface is an outer surface of the wall portion.

17. the pressure release structure includes at least one step of notched grooves, the at least one step of notched grooves being provided in the wall portion in order along a direction from the first surface to the second surface, and the opening area being provided in a first groove bottom wall of the notched groove in a step farthest from the first surface; The strength of the wall portion is D １ and the strength of the second groove bottom wall of the cut groove of the step closest to the first surface is D ２ and the strength of the portion of the first groove bottom wall where the score groove is located is D ３ and D ３ >D ２ ≧D １ and / or The hardness of the wall is E １ and the hardness of the second groove bottom wall is E ２ and the hardness of the bottom wall of the first groove at the location where the score groove is located is E ３ and E ３ >E ２ ≧E １ and / or The rigidity of the wall portion is F １ and the stiffness of the second groove bottom wall is F ２ and the stiffness of the bottom wall of the first groove at the location where the score groove is located is F ３ and F ３ >F ２ ≧F １ The battery cell according to any one of claims 4 to 16, which satisfies the above.

18. 1.2E １ ≦E ２ ≦2.5E １ The battery cell of claim 17 , wherein

19. 2.5E １ <E ３ ≦5E １ The battery cell of claim 17 , wherein

20. 5HBW≦E １ The battery cell according to any one of claims 17 to 19, which satisfies ≦150HBW.

21. 5HBW≦E ３ The battery cell according to any one of claims 17 to 20, which satisfies ≦200HBW.

22. The minimum thickness of the first groove bottom wall at the location where the score groove is located is W １ and 5HBW / mm≦E ３ / W １ ≦10000HBW / mm, preferably 190HBW / mm≦E ３ / W １ The battery cell according to any one of claims 17 to 21, wherein the cell satisfies ≦4000HBW / mm.

23. The minimum thickness of the wall portion at the location where the score groove is located is W １ and the minimum thickness of the wall is W ２ and 0.05≦W １ / W ２ The battery cell according to any one of claims 4 to 22, wherein the battery cell satisfies ≦0.

95.

24. 0.12≦W １ / W ２ ≦0.8, and preferably 0.2≦W １ / W ２ 24. The battery cell of claim 23, wherein the ratio satisfies ≦0.

5.

25. 0.02 mm≦W １ ≦1.6 mm, preferably 0.06 mm≦W １ The battery cell according to claim 23 or 24, wherein the thickness satisfies ≦0.4 mm.

26. 1mm≦W ２ ≦5 mm, preferably 1.2 mm≦W ２ ≦3.5 mm, and preferably 2 mm≦W ２ The battery cell according to any one of claims 22 to 25, wherein the thickness satisfies ≦3 mm.

27. the pressure release structure includes at least one step of notched grooves, the at least one step of notched grooves being provided in the wall portion in order along a direction from the first surface to the second surface, and the opening area being provided in a first groove bottom wall of the notched groove in a step farthest from the first surface; The average size of the crystal grains of the wall is G １ and the average size of the crystal grains of the second groove bottom wall of the cut groove at the step closest to the first surface is G ２ and the average size of the crystal grains at the bottom wall of the first groove where the score groove is located is G ３ and G １ >G ２ >G ３ The battery cell according to any one of claims 4 to 26, wherein

28. G ３ / G １ 28. The battery cell of claim 27, wherein the ratio satisfies ≦0.

9.

29. G ３ / G １ ≧0.05, preferably 0.1≦G ３ / G １ 29. The battery cell of claim 28, wherein the ratio satisfies ≦0.

5.

30. 0.4 μm≦G ３ ≦75 μm, preferably 1 μm≦G ３ The battery cell according to any one of claims 27 to 29, wherein the thickness satisfies ≦10 μm.

31. 10 μm≦G １ ≦150 μm, preferably 30 μm≦G １ The battery cell according to any one of claims 27 to 30, wherein the thickness satisfies ≦100 μm.

32. The minimum thickness of the first groove bottom wall at the location where the score groove is located is W １ and The average size of the crystal grains at the bottom wall of the first groove where the score groove is located is G ３ and 1≦W １ / G ３ ≦100, and preferably 5≦W １ / G ３ The battery cell according to any one of claims 27 to 31, wherein the battery cell satisfies ≦20.

33. The battery cell of any one of claims 1 to 32, wherein the housing includes a housing body and a cap, the housing body has an opening, the cap is connected to the housing body to seal the opening, and the pressure release structure is provided on the cap.

34. The battery cell of any one of claims 1 to 33, wherein the housing includes a housing body and a cap, the housing body has an opening, the cap is connected to the housing body to seal the opening, and the pressure release structure is provided on the housing body.

35. 35. The battery cell of claim 34, wherein the housing body has an opening at each end in the first direction, the housing includes two caps, and the caps seal the openings in a one-to-one relationship.

36. A battery comprising the battery cell according to any one of claims 1 to 35.

37. 37. An electrical device comprising the battery of claim 36, said battery providing electrical energy to said electrical device.

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