Battery cell, battery and electrical device

Abstract

The present application belongs to the technical field of batteries. Provided are a battery cell, a battery and an electrical device. The battery cell comprises a housing and a pressure relief component. The housing is provided with a wall portion. The pressure relief component is provided on the wall portion. The pressure relief component has a first region, a first weak portion being formed in the first region. The pressure relief component is configured to be capable of cracking along at least part of the first weak portion during pressure relief of the battery cell, so as to release internal pressure of the battery cell. The first weak portion comprises at least one weak section; the area of the cross section of the weak section perpendicular to the extending direction thereof is S, and, in the thickness direction of the wall portion, the thickness of the first region is D1, satisfying 0.008mm2≤S≤0.12mm2, and 0.2mm≤D1≤0.8mm. Thus, the present application can mitigate the phenomena such as premature cracking of pressure relief components during use, and improve the timeliness of pressure relief of the pressure relief component, thereby prolonging the service life and improving the use reliability of the battery cell.

Description

Battery cells, batteries and electrical devices Technical Field

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

[0002] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. With the vigorous promotion of new energy vehicles, the demand for power battery products is also growing. As a core component of new energy vehicles, batteries have high requirements in terms of reliability and service life.

[0003] In battery technology, to ensure the safety of battery cells, a pressure relief component is typically installed on the outer casing of the battery cell to release internal pressure. This component activates to release pressure when the internal pressure or temperature of the battery cell reaches a threshold. However, existing pressure relief components in battery cells are prone to premature actuation and cracking during use, resulting in poor stability and the risk of bursting or explosion during thermal runaway. This negatively impacts the lifespan and reliability of the battery cells.

[0004] Summary of the Invention

[0005] The embodiments of the present application provide a battery cell, a battery, and an electrical device, which can effectively improve the service life and reliability of the battery cell.

[0006] In a first aspect, an embodiment of the present application provides a battery cell, comprising a housing and a pressure relief component; the housing has a wall portion; the pressure relief component is arranged on the wall portion, the pressure relief component has a first area, the first area is formed with a first weak portion, and the pressure relief component is configured to be able to rupture along at least a portion of the first weak portion when the battery cell is depressurized to release the internal pressure of the battery cell; wherein the first weak portion includes at least one weak section, the area of ​​the cross section of the weak section perpendicular to its extension direction is S, and the thickness of the first area along the thickness direction of the wall portion is D1, which satisfies, 0.008mm 2 ≤S≤0.12mm 2 , 0.2mm≤D1≤0.8mm.

[0007] In the above technical solution, the thickness of the first region is set to 0.2mm to 0.8mm, and correspondingly, the cross-sectional area of ​​the weak section of the first weak portion perpendicular to its extension direction is set to 0.008mm. 2 to 0.12mm 2On the one hand, by setting the thickness of the first region to be less than or equal to 0.8 mm, and setting the cross-sectional area of ​​the weak section of the first weak portion perpendicular to its extension direction to be greater than or equal to 0.008 mm 2 , so as to reduce the concentration of stress generated by the expansion of the battery cell in the weak section of the first weak part, and improve the absorption effect of the first area on stress, thereby effectively alleviating the phenomenon of tensile deformation and the like in the weak section of the first weak part of the pressure relief component, so as to reduce the strain and strain amplitude of the first weak part of the pressure relief component, thereby reducing the phenomenon of reduced structural strength of the first weak part of the pressure relief component due to excessive strain and strain amplitude, so as to improve the use stability of the pressure relief component, and alleviate the phenomenon of premature cracking of the pressure relief component during use, which is beneficial to prolonging the service life of the battery cell. On the other hand, by setting the thickness of the first area to be greater than or equal to 0.2 mm, and setting the area of ​​the cross section of the weak section of the first weak part perpendicular to its extension direction to be less than or equal to 0.12 mm 2 , in order to reduce the bursting pressure required by the pressure relief component during pressure relief, thereby improving the timeliness of pressure relief of the pressure relief component, so as to improve the reliability of the battery cell during thermal runaway, and thus help to reduce the risk of bursting or explosion of the battery cell during thermal runaway, so that while taking into account the improvement of the service life of the battery cell, it can also effectively improve the reliability of the battery cell.

[0008] In some embodiments, a first groove is provided on the first region, and a bottom of the first groove forms at least one of the weak sections.

[0009] In the above technical solution, by providing a first groove on the first area, at least one weak section of the first weak portion is formed in the area where the first groove is provided and corresponding to the bottom surface of the first groove. A battery cell with such a structure facilitates forming a weak section of the first weak portion on the first area of ​​the pressure relief component, which is beneficial to reducing the difficulty of forming the first weak portion on the first area, thereby improving the production efficiency of the battery cell.

[0010] In some embodiments, the maximum width of the weak section is W, and the minimum thickness of the weak section along the thickness direction of the wall portion is D2. The product of the maximum width W of the weak section and the minimum thickness D2 of the weak section is the area S of the cross section of the weak section perpendicular to its extension direction, satisfying 0.1mm≤W≤0.3mm, 0.08mm≤D2≤0.4mm.

[0011] In the above technical solution, the area S of the cross section of the weak section of the first weak portion perpendicular to its extension direction is the product of the minimum thickness D2 of the weak section and the maximum width W of the weak section. The maximum width of the weak section is set to 0.1mm to 0.3mm, and correspondingly, the minimum thickness of the weak section is set to 0.08mm to 0.4mm. On the one hand, by setting the maximum width of the weak section to be greater than or equal to 0.1mm and the minimum thickness of the weak section to be greater than or equal to 0.08mm, the concentration of stress generated by the expansion of the battery cell in the weak section of the first weak portion can be further reduced, and the stress absorption effect of the first region can be further improved. , thereby further reducing the strain and strain amplitude of the first weak portion of the pressure relief component, and further alleviating the phenomenon of premature cracking of the pressure relief component during use, so as to further improve the service life of the battery cell. On the other hand, by setting the maximum width of the weak section to be less than or equal to 0.3 mm, and setting the minimum thickness of the weak section to be less than or equal to 0.4 mm, the bursting pressure required by the pressure relief component during pressure relief is further reduced, thereby further improving the timeliness of pressure relief of the pressure relief component, and further improving the reliability of the battery cell during thermal runaway, which is conducive to further reducing the risk of bursting or explosion of the battery cell during thermal runaway.

[0012] In some embodiments, the maximum width of the weak section is W, satisfying 0.16 mm ≤ W ≤ 0.24 mm.

[0013] In the above technical solution, by further setting the maximum width of the weak section to be greater than or equal to 0.16 mm, the phenomenon of premature cracking of the pressure relief component during use is further alleviated, which is beneficial to improving the service life of the battery cell and reducing the difficulty of processing the first groove. By further setting the maximum width of the weak section to be less than or equal to 0.24 mm, the phenomenon of the first groove occupying too much space is alleviated.

[0014] In some embodiments, the minimum thickness of the weak section is D2, satisfying 0.12 mm ≤ D2 ≤ 0.3 mm.

[0015] In the above technical solution, the minimum thickness of the weak section is further set to be greater than or equal to 0.12 mm, thereby further reducing the difficulty of machining the first groove. The minimum thickness of the weak section is further set to be less than or equal to 0.13 mm, thereby further improving the timeliness of the pressure relief component's pressure relief, thereby improving the reliability of the battery cell during thermal runaway and further reducing the risk of battery cell rupture or explosion during thermal runaway.

[0016] In some embodiments, along the thickness direction of the wall portion, the first groove is provided on a side of the first region facing away from the interior of the housing.

[0017] In the above technical solution, by arranging the first groove on the outer surface of the first area away from the interior of the shell, it is convenient to form the first groove on the first area, which is beneficial to reduce the processing difficulty of the first groove and improve the production efficiency of the battery cell.

[0018] In some embodiments, the first groove includes a plurality of grooves sequentially arranged along the thickness direction of the wall portion.

[0019] In the above technical solution, the first groove is set as a stepped groove structure arranged along the thickness direction of the wall portion, so that the first groove is a groove formed by multiple processing. The first groove with this structure can reduce the depth of the first groove in a single processing under the condition of the same depth, which is beneficial to reducing the manufacturing difficulty of the first groove and the demand for manufacturing equipment, so as to reduce the manufacturing cost, and can reduce the forming force applied to the first area during the single processing of the first groove, which is beneficial to reduce the risk of cracks in the first area, so as to improve the production quality of the battery cell. On the other hand, it can improve the flow morphology of the first groove during the formation process, which is beneficial to the flow of the material generated when the first groove is formed, so as to improve the structural consistency of the first groove.

[0020] In some embodiments, the first groove is an annular groove connected end to end, and the bottom of the first groove forms the weak section of the annular structure.

[0021] In the above technical solution, by setting the first groove as an annular structure connected end to end, on the one hand, the difficulty of processing and forming the first groove on the first area can be reduced; on the other hand, when the battery cell is depressurized, the area within the first groove of the annular structure can be completely detached, which is beneficial to increasing the pressure relief area of ​​the battery cell.

[0022] In some embodiments, the first groove includes a first groove section and a second groove section, the first groove section is connected to the second groove section, the bottom of the first groove section and the bottom of the second groove section both form the weak section, and the first groove section and the second groove section jointly define a predetermined pressure relief area, and the predetermined pressure relief area is configured to be able to be opened when the pressure relief component is cracked along at least a portion of the first weak portion to release the internal pressure of the battery cell.

[0023] In the above technical solution, the first groove is provided with a first groove section and a second groove section, and the first groove section and the second groove section are interconnected structures so that the first groove section and the second groove section jointly define a predetermined pressure relief area. On the one hand, it can increase the pressure relief area of ​​the battery cell to increase the pressure relief rate of the battery cell. On the other hand, it makes the position where the first groove section and the second groove section are connected to each other weaker, which is easier to crack and open the predetermined pressure relief area to release the internal pressure of the battery cell.

[0024] In some embodiments, the first groove includes a first groove segment, a second groove segment, and a third groove segment, the bottom of the first groove segment, the bottom of the second groove segment, and the bottom of the third groove segment all form the weak segment, the first groove segment and the third groove segment are arranged opposite to each other, the second groove segment connects the first groove segment and the third groove segment, the first groove segment, the second groove segment, and the third groove segment jointly define a predetermined pressure relief area, and the predetermined pressure relief area is configured to be able to be opened when the pressure relief component is cracked along at least a portion of the first weak portion to release the internal pressure of the battery cell.

[0025] In the above technical solution, the first groove is provided with a first groove section and a third groove section arranged opposite to each other, and a second groove section connecting the first groove section and the third groove section, so that the pressure relief component can split along the first groove section, the second groove section and the third groove section when the battery cell releases pressure, so as to open the predetermined pressure relief area to release the internal pressure of the battery cell. The first groove with such a structure makes the intersection position of the first groove section and the second groove section and the intersection position of the second groove section and the third groove section weaker, easier to split and open the predetermined pressure relief area for pressure relief, and can further improve the pressure relief area and pressure relief rate of the battery cell.

[0026] In some embodiments, the connection position of the first trough section and the second trough section deviates from the two ends of the first trough section, and the connection position of the third trough section and the second trough section deviates from the two ends of the third trough section, so that the predetermined pressure relief area is formed on both sides of the second trough section.

[0027] In the above technical solution, by setting the connection position of the first groove segment and the second groove segment to be located between the two ends of the first groove segment, and setting the connection position of the third groove segment and the second groove segment to be located between the two ends of the third groove segment, the first groove segment, the second groove segment and the third groove segment form an "H"-shaped structure, so that predetermined pressure relief areas can be formed on both sides of the second groove segment of the first groove, and the two predetermined pressure relief areas can be opened in a split manner to relieve pressure when the battery cell is depressurized, which is beneficial to further increase the pressure relief effect of the battery cell and can effectively improve the pressure relief rate of the battery cell.

[0028] In some embodiments, the first slot segment, the second slot segment, and the third slot segment all extend along a straight line, and the first slot segment and the third slot segment are both perpendicular to the second slot segment.

[0029] In the above technical solution, by setting the first groove section, the second groove section and the third groove section to extend along a straight line, and setting the first groove section and the third groove section to be perpendicular to the second groove section, so that the extension direction of the second groove section is the arrangement direction of the first groove section and the third groove section, on the one hand, the regularity of the shape of the first groove can be improved, which is conducive to reducing the processing difficulty of the first groove, thereby reducing the manufacturing cost of the battery cell; on the other hand, the two predetermined pressure relief areas located on both sides of the second groove section relieve pressure in opposite directions when the battery cell is depressurized.

[0030] In some embodiments, the first slot segment, the second slot segment, and the third slot segment all extend along an arc trajectory.

[0031] In the above technical solution, by setting the first groove section, the second groove section and the third groove section as structures extending along an arc trajectory, it is beneficial to improve the arc degree of the connection position of the first groove section and the second groove section, and the arc degree of the connection position of the second groove section and the third groove section. On the one hand, it can reduce the difficulty of processing the first groove, and on the other hand, it can facilitate the first area of ​​the pressure relief component to open the predetermined pressure relief area after it is cracked along the first groove section, the second groove section and the third groove section to release the internal pressure of the battery cell.

[0032] In some embodiments, the first groove further includes a fourth groove segment, the bottom of the fourth groove segment forms the weak segment, the fourth groove segment is located between the first groove segment and the third groove segment, and the fourth groove segment is connected to the second groove segment.

[0033] In the above technical solution, the first groove is further provided with a fourth groove segment located between the first groove segment and the third groove segment, and the fourth groove segment is interconnected with the second groove segment, so that the stress at the position where the fourth groove segment and the second groove segment are interconnected is more concentrated and easier to rupture, so that the pressure relief component ruptures along the second groove segment from the position where the second groove segment and the fourth groove segment intersect during the pressure relief process, and ruptures along the first groove segment and the third groove segment after the second groove segment ruptures, so as to achieve rapid pressure relief.

[0034] In some embodiments, a second weak portion is further formed in the first area, and along the thickness direction of the wall portion, the thickness of the second weak portion is greater than the thickness of the first weak portion. The second weak portion is configured to guide the predetermined pressure relief zone to flip when the first weak portion is ruptured to release the internal pressure of the battery cell.

[0035] In the above technical solution, a second weak portion is further provided in the first area, and the thickness of the second weak portion is greater than that of the first weak portion, so that the pressure relief component can preferentially crack along the first weak portion and open the predetermined pressure relief area, and the predetermined pressure relief area can be flipped with the second weak portion as the axis when being opened, thereby improving the opening effect of the predetermined pressure relief area of ​​the pressure relief component, which is beneficial to increasing the pressure relief area of ​​the battery cell after the predetermined pressure relief area is opened, and further improving the pressure relief rate of the battery cell when thermal runaway occurs, so as to reduce the risk of fire, explosion or connection failure of the battery cell due to untimely pressure relief, and is beneficial to improving the reliability of the battery cell.

[0036] In some embodiments, a second groove is provided in the first area, and a bottom of the second groove forms the second weak portion.

[0037] In the above technical solution, a second groove is provided on the first area, so that a second weak portion is formed in the area of ​​the first area where the second groove is provided and corresponding to the bottom surface of the second groove. The battery cell adopting this structure facilitates the formation of the second weak portion on the first area of ​​the pressure relief component, which is beneficial to reducing the difficulty of forming the second weak portion on the first area, thereby improving the production efficiency of the battery cell.

[0038] In some embodiments, along the thickness direction of the wall portion, the second groove is provided on a side of the first region facing the interior of the housing.

[0039] In the above technical solution, by arranging the second groove on the surface of the first area facing the interior of the shell, the predetermined pressure relief zone can be flipped toward the outside of the shell around the bottom wall of the second groove when it is opened, thereby reducing the interference effect of the groove side surface of the second groove on the predetermined pressure relief zone during the flipping process, which is beneficial to improving the flipping effect of the predetermined pressure relief zone.

[0040] In some embodiments, along the thickness direction of the wall portion, the first groove and the second groove are respectively provided on both sides of the first region.

[0041] In the above technical solution, by arranging the first groove and the second groove on both sides of the first area respectively, it is convenient to process the first groove and the second groove on both sides of the first area respectively, which is beneficial to reduce the mutual influence between the first groove and the second groove during the processing.

[0042] In some embodiments, along the thickness direction of the wall portion, a projection of the first groove and a projection of the second groove do not overlap.

[0043] In the above technical solution, by setting the first groove and the second groove to a structure in which the projections in the thickness direction of the wall portion do not overlap with each other, so that the first groove and the second groove do not contact each other, on the one hand, the mutual influence of the first groove and the second groove during the processing process can be reduced, and on the other hand, the phenomenon that the first weak portion causes the second weak portion to crack when the first weak portion cracks to release pressure can be reduced, and the stress influence between the first weak portion and the second weak portion can be reduced.

[0044] In some embodiments, the wall portion is a rectangular structure, the second groove extends along the length direction of the wall portion, and along the width direction of the wall portion, the second groove is located between the first groove and the edge of the wall portion.

[0045] In the above technical solution, by arranging the second groove between the first groove and the edge of the wall portion along the width direction of the wall portion, the second groove can also play a certain buffering role on the first groove, so that when the battery cell is subjected to internal and external impact forces and deformed, the second groove can also absorb the deformation energy of the battery cell, so as to play a certain protective role for the area where the first groove is provided in the pressure relief component, and thus can effectively reduce the deformation or damage of the area where the first groove is provided in the pressure relief component when the battery cell is subjected to internal and external impact forces, thereby alleviating the situation where the battery cell is prematurely actuated to release pressure during use.

[0046] In some embodiments, a third groove is provided on one side of the pressure relief component along the thickness direction of the wall portion, and the bottom of the third groove forms the first area.

[0047] In the above technical solution, a third groove is provided on one side of the pressure relief component, and the first area of ​​the pressure relief component is formed at the bottom of the third groove, so that the first area of ​​the pressure relief component is an area where the thickness of the pressure relief component is thinned, so that the structural strength of the first area can be weaker than the structural strength of the area where the pressure relief component is not thinned, so as to further enhance the first area's absorption effect on the stress generated by the expansion of the battery cell, and further alleviate the phenomenon that the stress is transferred to the first weak portion and the stress concentration is generated in the first weak portion, so as to reduce the strain and strain amplitude of the first weak portion of the pressure relief component, which is beneficial to alleviate the phenomenon of premature cracking of the pressure relief component during use, so as to enhance the service life of the battery cell.

[0048] In some embodiments, along the thickness direction of the wall portion, the third groove is provided on a side of the pressure relief component facing away from the interior of the housing.

[0049] In the above technical solution, by arranging the third groove on the outer surface of the pressure relief component away from the interior of the shell, it is convenient to form the third groove on the pressure relief component, which is beneficial to reduce the processing difficulty of the third groove and improve the production efficiency of the battery cell.

[0050] In some embodiments, the pressure relief component is separately provided from the wall portion.

[0051] In the above technical solution, by arranging the pressure relief component and the wall portion as a separate structure, the pressure relief component is a structure installed on the wall portion. The battery cell adopting this structure can reduce the difficulty of arranging the pressure relief component on the wall portion, and the processing steps of the shell and the pressure relief component can be carried out simultaneously, which is conducive to optimizing the production rhythm of the battery cell.

[0052] In some embodiments, the pressure relief component is integrally formed with the wall portion.

[0053] In the above technical solution, the pressure relief component and the wall portion are arranged as an integrally formed structure, so that the pressure relief component is a structure integrated on the wall portion, that is, the pressure relief component is a wall of the shell, and correspondingly, the wall portion is provided with structures such as the first area and the first weak portion. The battery cell adopting this structure can improve the structural strength of the pressure relief component provided on the wall portion, and can reduce the risk of leakage caused by improper assembly between the pressure relief component and the wall portion.

[0054] In some embodiments, the housing includes a shell and an end cover; a housing having an opening is formed inside the shell, and the housing is used to accommodate the electrode assembly; the end cover closes the opening; wherein the end cover is the wall portion; or, the shell includes the wall portion.

[0055] In the above technical solution, by configuring the wall portion of the housing as an end cap for closing the opening of the housing, a battery cell employing this structure facilitates the provision of a pressure relief component on the end cap, thereby reducing the difficulty of manufacturing the battery cell and improving the production efficiency of the battery cell. By configuring the wall portion of the housing as a wall of the shell, a battery cell employing this structure can position the area of ​​the housing where the pressure relief component is provided away from the end cap, thereby effectively alleviating the stress generated by the connection between the end cap and the shell from acting on the pressure relief component, thereby reducing the impact on the first area and the first weak portion of the pressure relief component, and thereby facilitating the reduction of the risk of cracking or a decrease in the structural strength of the pressure relief component under the pulling effect of the stress, thereby improving the service life and reliability of the battery cell.

[0056] In some embodiments, the outer shell includes a shell and two end covers; a accommodating cavity is formed inside the shell, and the accommodating cavity is used to accommodate the electrode assembly, and openings are formed at both opposite ends of the shell, and both openings are connected to the accommodating cavity; the two end covers respectively close the two openings; wherein, one of the two end covers is the wall portion; or, the shell includes the wall portion.

[0057] In the above technical solution, the shell of the housing is provided with openings at both opposite ends, and the two end caps respectively close the two openings, and the wall portion is one of the two end caps. A battery cell adopting this structure facilitates the assembly of the battery cell from both ends of the housing, which is conducive to reducing the difficulty of manufacturing and assembling the battery cell. It is also convenient to set a pressure relief component on the end cap, which is conducive to reducing the difficulty of manufacturing the battery cell and improving the production efficiency of the battery cell. By setting the wall portion of the housing as a wall of the housing, a battery cell adopting this structure can make the area of ​​the housing where the pressure relief component is provided away from the end cap, thereby effectively alleviating the phenomenon of stress generated by the connection between the end cap and the housing acting on the pressure relief component, reducing the impact on the first area and the first weak portion of the pressure relief component, and further facilitating the reduction of the risk of cracking or structural strength reduction of the pressure relief component under the pulling action of stress, thereby improving the service life and reliability of the battery cell.

[0058] In a second aspect, an embodiment of the present application further provides a battery comprising the above-mentioned battery cell.

[0059] In a third aspect, an embodiment of the present application further provides an electrical device, comprising the above-mentioned battery cell, wherein the battery cell is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0061] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0062] FIG2 is an exploded view of the structure of a battery provided in some embodiments of the present application;

[0063] FIG3 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0064] FIG4 is an exploded view of the structure of a battery cell provided in some embodiments of the present application;

[0065] FIG5 is a schematic structural diagram of a pressure relief component of a battery cell provided in some embodiments of the present application;

[0066] FIG6 is a cross-sectional view of a pressure relief component of a battery cell provided in some embodiments of the present application;

[0067] FIG7 is a partial enlarged view of the pressure relief component at point A shown in FIG6 ;

[0068] FIG8 is a schematic structural diagram of a shell of a battery cell housing provided in yet other embodiments of the present application;

[0069] FIG9 is a bottom view of a housing of a battery cell provided in some other embodiments of the present application;

[0070] FIG10 is a partial cross-sectional view of a wall portion of a housing of a battery cell provided in some embodiments of the present application;

[0071] FIG11 is a partial enlarged view of a portion B of the wall portion of the housing of the battery cell shown in FIG10 ;

[0072] FIG12 is a bottom view of a housing of a battery cell provided in some further embodiments of the present application;

[0073] FIG13 is a bottom view of a housing of a battery cell provided in some other embodiments of the present application;

[0074] FIG14 is a bottom view of the shell of the battery cell housing provided in some other embodiments of the present application.

[0075] Icon: 1000-vehicle; 100-battery; 10-casing; 11-first casing body; 12-second casing body; 20-battery cell; 21-housing; 211-wall; 212-shell; 2121-opening; 213-end cover; 22-pressure relief component; 221-first area; 2211-first groove; 2211a-first groove section; 2211b-second groove section; 2211c-third groove section; 2211d-fourth groove section; 2212-predetermined pressure relief area; 2213-second groove; 222-first weak part; 2221-weak section; 223-second weak part; 224-third groove; 23-electrode assembly; 231-ear; 24-electrode terminal; 25-current collecting member; 200-controller; 300-motor; X-thickness direction of the wall; Y-length direction of the wall; Z-width direction of the wall. DETAILED DESCRIPTION

[0076] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0077] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0078] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0079] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0080] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0081] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0082] The term "plurality" used in this application refers to two or more (including two).

[0083] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0084] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0085] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0086] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0087] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0088] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0089] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include but are not limited to at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc.

[0090] In some embodiments, a positive electrode may utilize a metal foam. The metal foam may include nickel foam, copper foam, aluminum foam, alloy foam, or the like. When a metal foam is used as the positive electrode, the surface of the metal foam may or may not include a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled or / and deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0091] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0092] As an example, the negative electrode current collector may be a metal foil, a metal foam, or a composite current collector. For example, as the metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. may be used. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, etc. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0093] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0094] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0095] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0096] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0097] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0098] In some embodiments, the separator is a separator membrane. There are many types of separator membranes, and any known separator membrane with a porous structure having good chemical stability and mechanical stability can be selected.

[0099] As an example, the separator can be made of at least one of fiberglass, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. In the case of a multi-layer composite film, the materials of each layer can be the same or different. The separator can be a separate component positioned between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0100] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0101] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel, or solid. Liquid electrolytes include an electrolyte salt and a solvent.

[0102] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0103] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent may also be an ether solvent. The ether solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0104] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0105] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0106] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, or the like.

[0107] As an example, the inorganic solid electrolyte may include an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphosulfide, silver germanium sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0108] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0109] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0110] In some embodiments, the electrode assembly is a laminate structure.

[0111] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0112] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0113] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0114] As an example, a plurality of separators may be provided, each of which is disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0115] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0116] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0117] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0118] In some embodiments, a battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0119] As an example, the battery cells may be cylindrical, prismatic, soft-pack or other shaped battery cells. Prismatic battery cells include but are not limited to square-shell, blade-shaped, and polygonal batteries, such as hexagonal batteries.

[0120] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0121] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0122] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0123] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0124] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0125] Batteries, with their outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide adaptability, and low self-discharge coefficient, are a vital component of today's new energy development. The development of battery technology requires simultaneous consideration of multiple design factors, including performance parameters such as energy density, cycle life, discharge capacity, and charge / discharge rate. Furthermore, battery safety must also be considered.

[0126] In battery technology, for general battery cells, in order to ensure the safety of battery cells, a pressure relief component is usually provided on the battery cell to release the internal pressure of the battery cell through the pressure relief component, thereby effectively improving the safety of the battery cell. In related technologies, the pressure relief component is usually formed on the housing using an integral molding process, that is, integrated into the housing of the battery cell, or connected to the housing by welding, clamping, etc., so that when the internal pressure or temperature of the battery cell reaches a threshold, the pressure relief component can be actuated and opened to release the internal pressure of the battery cell. However, battery cells are prone to expansion during use or during charging and discharging. The expansion force generated by the battery cell directly acts on the pressure relief component, making it extremely prone to tensile deformation and other phenomena. This also causes strain and a large strain amplitude in the pressure relief component, thereby reducing the structural strength of the battery cell pressure relief component, resulting in poor stability in use of the pressure relief component. It is easy to cause the pressure relief component to actuate prematurely to release pressure or fatigue cracking during use, which is not conducive to improving the service life and reliability of the battery cell.

[0127] Based on the above considerations, in order to solve the problem of premature actuation of pressure relief or fatigue cracking of the pressure relief component of the battery cell during use, an embodiment of the present application provides a battery cell, the battery cell including a shell and a pressure relief component. The shell has a wall portion. The pressure relief component is arranged on the wall portion, and the pressure relief component has a first area, and the first area is formed with a first weak portion. The pressure relief component is configured to be able to crack along at least part of the first weak portion when the battery cell is depressurized to release the internal pressure of the battery cell. The first weak portion includes at least one weak section, and the area of ​​the cross section of the weak section perpendicular to its extension direction is S. The thickness of the first area along the thickness direction of the wall portion is D1, which satisfies, 0.008mm. 2 ≤S≤0.12mm 2 , 0.2mm≤D1≤0.8mm.

[0128] In the battery cell of this structure, the thickness of the first region is set to 0.2mm to 0.8mm, and correspondingly, the cross-sectional area of ​​the weak section of the first weak portion perpendicular to its extension direction is set to 0.008mm. 2 to 0.12mm 2On the one hand, by setting the thickness of the first region to be less than or equal to 0.8 mm, and setting the cross-sectional area of ​​the weak section of the first weak portion perpendicular to its extension direction to be greater than or equal to 0.008 mm 2 , so as to reduce the concentration of stress generated by the expansion of the battery cell in the weak section of the first weak part, and improve the absorption effect of the first area on stress, thereby effectively alleviating the phenomenon of tensile deformation and the like in the weak section of the first weak part of the pressure relief component, so as to reduce the strain and strain amplitude of the first weak part of the pressure relief component, thereby reducing the phenomenon of reduced structural strength of the first weak part of the pressure relief component due to excessive strain and strain amplitude, so as to improve the use stability of the pressure relief component, and alleviate the phenomenon of premature cracking of the pressure relief component during use, which is beneficial to prolonging the service life of the battery cell. On the other hand, by setting the thickness of the first area to be greater than or equal to 0.2 mm, and setting the area of ​​the cross section of the weak section of the first weak part perpendicular to its extension direction to be less than or equal to 0.12 mm 2 , in order to reduce the bursting pressure required by the pressure relief component during pressure relief, thereby improving the timeliness of pressure relief of the pressure relief component, so as to improve the reliability of the battery cell during thermal runaway, and thus help to reduce the risk of bursting or explosion of the battery cell during thermal runaway, so that while taking into account the improvement of the service life of the battery cell, it can also effectively improve the reliability of the battery cell.

[0129] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power supply system comprising the battery cells and batteries disclosed in this application can be used to construct such electrical devices. This can help alleviate issues such as premature cracking or delayed pressure relief in the pressure relief components of the battery cells during use, thereby improving the reliability and service life of the battery cells.

[0130] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0131] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device according to an embodiment of the present application.

[0132] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000. The battery 100 can be arranged at the bottom of the vehicle 1000, or at the head of the vehicle 1000, or at the tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can be used as an operating power source or a power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0133] In some embodiments of the present application, the battery 100 can not only serve as the operating power source or usage power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0134] 2 and 3 , FIG2 is an exploded view of a battery 100 according to some embodiments of the present invention, and FIG3 is a schematic diagram of a battery cell 20 according to some embodiments of the present invention. The battery 100 includes a housing 10 and a battery cell 20 , wherein the battery cell 20 is accommodated in the housing 10 .

[0135] The housing 10 is used to provide assembly space for the battery cells 20 and can adopt a variety of structures. In some embodiments, the housing 10 can include a first housing body 11 and a second housing body 12. The first housing body 11 and the second housing body 12 cover each other, and the first housing body 11 and the second housing body 12 jointly define an assembly space for accommodating the battery cells 20. The second housing body 12 can be a hollow structure with one end open, and the first housing body 11 can be a plate-like structure. The first housing body 11 covers the open side of the second housing body 12, so that the first housing body 11 and the second housing body 12 jointly define the assembly space. The first housing body 11 and the second housing body 12 can also be hollow structures with one end open, and the open side of the first housing body 11 covers the open side of the second housing body 12.

[0136] Of course, the box body 10 formed by the first box body 11 and the second box body 12 can be in various shapes, such as a cylinder, a cuboid or a cube, etc. For example, in FIG2 , the box body 10 is in the shape of a cuboid.

[0137] In the battery 100, there can be one or more battery cells 20 disposed within the housing 10. When there are multiple battery cells 20 disposed within the housing 10, the multiple battery cells 20 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel configurations within the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure formed by the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery 100 can be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid configuration to form a battery module, which is then further connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed within the housing 10.

[0138] In some embodiments, the battery 100 may further include other structures. For example, the battery 100 may further include a busbar component, which is used to connect the multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20 .

[0139] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can be a rectangular parallelepiped, a cylinder, a prism, or other shapes. For example, in FIG3 , the battery cell 20 is a rectangular parallelepiped.

[0140] According to some embodiments of the present application, referring to FIG3 and further referring to FIG4, FIG5, FIG6 and FIG7, FIG4 is an exploded view of the structure of a battery cell 20 provided in some embodiments of the present application, FIG5 is a schematic structural diagram of a pressure relief component 22 of a battery cell 20 provided in some embodiments of the present application, FIG6 is a cross-sectional view of the pressure relief component 22 of the battery cell 20 provided in some embodiments of the present application, and FIG7 is a partial enlarged view of the pressure relief component 22 shown in FIG6 at point A. The present application provides a battery cell 20, which includes a housing 21 and a pressure relief component 22. The housing 21 has a wall portion 211, and the pressure relief component 22 is disposed on the wall portion 211. The pressure relief component 22 has a first region 221, and the first region 221 is formed with a first weakened portion 222. The pressure relief component 22 is configured to rupture along at least a portion of the first weakened portion 222 when the battery cell 20 is depressurized, thereby releasing the internal pressure of the battery cell 20. The first weak portion 222 includes at least one weak section 2221. The cross-sectional area of ​​the weak section 2221 perpendicular to its extension direction is S. Along the thickness direction X of the wall, the thickness of the first region 221 is D1, which satisfies 0.008 mm. 2 ≤S≤0.12mm 2 , 0.2mm≤D1≤0.8mm.

[0141] 4 , the battery cell 20 may further include an electrode assembly 23, which is housed in the outer shell 21. The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. The structure of the electrode assembly 23 may be various. For example, the electrode assembly 23 may be a wound structure formed by winding a positive electrode sheet, an isolating member, and a negative electrode sheet, or a stacked structure formed by stacking a positive electrode sheet, an isolating member, and a negative electrode sheet.

[0142] Illustratively, the separator is an isolation membrane, and a main material of the isolation membrane may be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0143] Optionally, the number of electrode assemblies 23 housed within the housing 21 may be one or more. For example, in FIG4 , two electrode assemblies 23 are disposed within the housing 21 of the battery cell 20, and the two electrode assemblies 23 are stacked along the thickness of the battery cell 20. In other embodiments, the number of electrode assemblies 23 housed within the housing 21 may be one, three, four, five, six, seven, or eight.

[0144] The housing 21 can also be used to contain an electrolyte, such as an electrolyte solution. The housing 21 can have various structural forms, such as a cylinder, a rectangular parallelepiped, or a prismatic structure. Similarly, the housing 21 can be made of various materials, such as copper, iron, aluminum, steel, or an aluminum alloy.

[0145] In some embodiments, the housing 21 may include a shell 212 and an end cover 213, and a accommodating cavity is formed inside the shell 212, which is used to accommodate the electrode assembly 23, and the accommodating cavity has an opening 2121. That is, the shell 212 is a hollow structure with an opening 2121 at one end, and the end cover 213 covers the opening 2121 of the shell 212 and forms a sealed connection to form an enclosed space for accommodating the electrode assembly 23 and the electrolyte.

[0146] It should be noted that the wall portion 211 provided with the pressure relief component 22 can be the end cap 213 of the outer shell 21 or a wall of the housing 212 of the outer shell 21. For example, in Figures 3 and 4, the wall portion 211 is the end cap 213. Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the wall portion 211 can also be the bottom wall of the housing 212 disposed opposite the end cap 213, or the side wall of the housing 212 and the end cap 213 adjacent to and connected to each other.

[0147] When assembling the battery cell 20 , the electrode assembly 23 may be placed in the housing 212 first, and the housing 212 may be filled with electrolyte. The end cap 213 may then be placed on the opening 2121 of the housing 212 to complete the assembly of the battery cell 20 .

[0148] The shell 212 can be in various shapes, such as a cylinder, a cuboid or a prismatic structure. The shape of the shell 212 can be determined according to the specific shape of the electrode assembly 23. For example, if the electrode assembly 23 is a cylindrical structure, a shell 212 with a cylindrical structure can be selected; if the electrode assembly 23 is a cuboid structure, a shell 212 with a cuboid structure can be selected. Of course, the structure of the end cover 213 can also be various, for example, the end cover 213 is a plate-like structure or a hollow structure with one end open. For example, in Figure 4, the shell 212 is a cuboid structure, the length direction Y of the wall is the length direction of the battery cell 20, the width direction Z of the wall is the thickness direction of the battery cell 20, and the thickness direction X of the wall is the height direction of the battery cell 20.

[0149] Of course, it is understandable that the shell 21 is not limited to the above structure. The shell 21 may also be other structures. For example, the shell 21 may include a shell body 212 and two end covers 213. The shell body 212 is a hollow structure with openings 2121 on opposite sides. One end cover 213 corresponds to an opening 2121 of the shell body 212 and forms a sealed connection to form an enclosed space for accommodating the electrode assembly 23 and the electrolyte. That is, the shell body 212 is formed with openings 2121 on opposite sides, and the two end covers 213 are respectively covered on both sides of the shell body 212 to close the corresponding openings 2121.

[0150] In some embodiments, as shown in Figures 3 and 4, the battery cell 20 may further include an electrode terminal 24, which is insulated and mounted on the housing 21 and electrically connected to the electrode assembly 23 to output or input electrical energy of the battery cell 20.

[0151] It should be noted that the electrode terminal 24 is insulated and mounted on the housing 21 , that is, no electrical connection is formed between the electrode terminal 24 and the housing 21 .

[0152] In Figures 3 and 4 , the battery cell 20 includes two electrode terminals 24, which are spaced apart along the length direction Y of the wall. Correspondingly, each electrode assembly 23 has two tabs 231, which are spaced apart along the length direction Y of the wall and have opposite polarities. The two electrode terminals 24 are electrically connected to the two tabs 231 of the electrode assembly 23, respectively, to enable input or output of the positive and negative electrodes of the battery cell 20. It should be noted that the tabs 231 of the electrode assembly 23 are formed by overlapping and connecting the regions of the positive electrode sheet not coated with the positive electrode active material layer, or by overlapping and connecting the regions of the negative electrode sheet not coated with the negative electrode active material layer. If the tab 231 is used for the positive electrode of the output electrode assembly 23, the tab 231 is a component formed by stacking and connecting the areas on the positive electrode sheet that are not coated with the positive electrode active material layer; if the tab 231 is used for the negative electrode of the output electrode assembly 23, the tab 231 is a component formed by stacking and connecting the areas on the negative electrode sheet that are not coated with the negative electrode active material layer.

[0153] Exemplarily, the electrode terminal 24 may be made of a variety of materials. For example, the electrode terminal 24 may be made of copper, iron, aluminum, steel, or aluminum alloy.

[0154] Optionally, the electrode terminals 24 may be mounted on the outer shell 21 in various structures. For example, in Figures 3 and 4, both electrode terminals 24 are mounted on the end cap 213 of the outer shell 21. Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, both electrode terminals 24 may be mounted on the shell 212 of the outer shell 21. Similarly, one electrode terminal 24 may be mounted on the shell 212 of the outer shell 21, and the other electrode terminal 24 may be mounted on the end cap 213 of the outer shell 21.

[0155] In some embodiments, as shown in Figure 4, the battery cell 20 may also include two current collecting components 25, both of which are arranged in the outer shell 21 and are spaced apart along the length direction Y of the wall. Each current collecting component 25 is used to connect an electrode terminal 24 and a plurality of electrode tabs 231 with the same polarity in the electrode assemblies 23 to achieve electrical connection between the electrode terminal 24 and the electrode assembly 23, which is beneficial to reduce the difficulty of assembly between the tab 231 and the electrode terminal 24.

[0156] Exemplarily, the material of the current collecting member 25 may be various, for example, the material of the current collecting member 25 may be copper, iron, aluminum, steel or aluminum alloy.

[0157] In the embodiment of the present application, the pressure relief component 22 serves to relieve pressure in the battery cell 20 , and is used to release the pressure inside the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value.

[0158] Alternatively, the pressure relief component 22 may have various structures. For example, the pressure relief component 22 may be separate from the wall 211 of the housing 21, or may be integrally formed with the wall 211 of the housing 21. When the pressure relief component 22 is separate from the wall 211 of the housing 21, that is, the wall 211 of the housing 21 is provided with a pressure relief hole for mounting the pressure relief component 22, and the pressure relief component 22 is connected to the wall 211 and covers the pressure relief hole. The connection between the pressure relief component 22 and the wall 211 may be various methods, such as welding or clamping. When the pressure relief component 22 is integrally formed with the wall 211 of the housing 21, that is, the pressure relief component 22 is a wall of the housing 21, that is, the pressure relief component 22 is integrated with the wall 211 and forms a wall of the housing 21. Accordingly, the pressure relief component 22 is formed with a weakened structure formed on the wall 211 that is designed to break when the battery cell 20 releases pressure.

[0159] For example, in Figures 3 and 4, the pressure relief component 22 and the wall portion 211 are separately arranged structures, and the pressure relief component 22 is welded to the wall portion 211, that is, a pressure relief hole for installing the pressure relief component 22 is provided on the wall portion 211, and the pressure relief component 22 is welded to the wall portion 211 and covers the pressure relief hole.

[0160] Referring to Figure 8 , which illustrates the structure of the housing 212 of the outer shell 21 of a battery cell 20 according to yet other embodiments of the present application, the pressure relief component 22 is integrally formed with the wall portion 211 . Specifically, the pressure relief component 22 is formed as the wall portion 211 , and the first weak portion 222 and the first region 221 are both formed on the wall portion 211 .

[0161] The pressure relief component 22 has a first area 221, that is, the first area 221 is a part of the pressure relief component 22. For example, in Figures 5 and 6, the pressure relief component 22 is provided with a third groove 224 on one side of the wall portion in the thickness direction X, and the pressure relief component 22 forms the first area 221 in the area corresponding to the bottom surface of the third groove 224. As shown in Figure 8, if the pressure relief component 22 and the wall portion 211 are an integrally formed structure, the third groove 224 is provided on one side of the wall portion 211, that is, the area of ​​the first wall provided with the third groove 224 and the portion corresponding to the bottom surface of the third groove 224 is the first area 221.

[0162] The first weak portion 222 includes at least one weak section 2221. It should be noted that the weak section 2221 of the first weak portion 222 is a structure extending along a smooth trajectory, such as a structure extending along a straight line or an arc. The weak section 2221 of the first weak portion 222 can be one or more. If the first weak portion 222 is a straight line structure, an arc structure or a ring structure, the first weak portion 222 only includes one weak section 2221. If the first weak portion 222 is a "V"-shaped structure, a "U"-shaped structure or an "H"-shaped structure, the first weak portion 222 includes multiple weak sections 2221. For example, in FIG5 , a first groove 2211 is provided on the first region 221 of the pressure relief component 22, and a first weak portion 222 is formed at the bottom of the first groove 2211. The first groove 2211 is an annular groove, and the first weak portion 222 only includes one weak section 2221. For another example, in FIG8 , a first groove 2211 is provided on the first region 221 of the pressure relief component 22, and a first weak portion 222 is formed at the bottom of the first groove 2211. The first groove 2211 includes a first groove section 2211a, a second groove section 2211b, a third groove section 2211c, and a fourth groove section 2221. 11d, the first slot segment 2211a and the third slot segment 2211c are arranged opposite to each other, the second slot segment 2211b connects the first slot segment 2211a and the third slot segment 2211c, the fourth slot segment 2211d is located between the first slot segment 2211a and the third slot segment 2211c, and the fourth slot segment 2211d is connected to the second slot segment 2211b, then the bottom of the first slot segment 2211a, the bottom of the second slot segment 2211b, the bottom of the third slot segment 2211c and the bottom of the fourth slot segment 2211d all form weak sections 2221, and the first weak portion 222 includes four weak sections 2221.

[0163] The area S of the cross section of the weak section 2221 perpendicular to its extension direction is the product of the maximum width of the bottom surface of the first groove 2211 and the minimum residual thickness of the first groove 2211. It should be noted that the bottom surface of the first groove 2211 and the side surface of the first groove 2211 can be directly connected or indirectly connected. For example, the bottom surface of the first groove 2211 and the side surface of the first groove 2211 can be connected via a circular chamfered surface, that is, a circular chamfer is formed between the bottom surface of the first groove 2211 and the side surface of the first groove 2211. If the bottom surface of the first groove 2211 and the side surface of the first groove 2211 are indirectly connected, the area S of the cross section of the weak section 2221 perpendicular to its extension direction is the product of the maximum width of the bottom surface of the first groove 2211 and the minimum thickness of the pressure relief component 22 in the area corresponding to the bottom surface of the first groove 2211.

[0164] The thickness of the first region 221 is D1. In an embodiment in which the pressure relief component 22 and the wall portion 211 are separately provided, if the first region 221 is the region corresponding to the bottom of the third groove 224 of the pressure relief component 22, then D1 is the residual thickness of the pressure relief component 22 at the third groove 224 in the thickness direction X of the wall portion. If the pressure relief component 22 is not provided with the third groove 224, then D1 is the thickness of the region of the pressure relief component 22 in the thickness direction X of the wall portion where the first groove 2211 is not provided. In an embodiment in which the pressure relief component 22 and the wall portion 211 are integrally formed, if the first region 221 is the region corresponding to the bottom of the third groove 224 of the wall portion 211, then D1 is the residual thickness of the wall portion 211 at the third groove 224 in the thickness direction X of the wall portion. If the wall portion 211 is not provided with the third groove 224, then D1 is the thickness of the region of the wall portion 211 in the thickness direction X of the wall portion where the first groove 2211 is not provided.

[0165] For example, the cross-sectional area S of the weak section 2221 of the first weak portion 222 perpendicular to its extension direction may be 0.008 mm. 2 , 0.009mm 2 , 0.01mm 2 , 0.0156mm 2 , 0.02mm 2 , 0.0256mm 2 , 0.03mm 2 , 0.038mm 2 , 0.04mm 2 , 0.05mm 2 , 0.0504mm 2 , 0.06mm 2 , 0.07mm 2 , 0.072mm 2 , 0.08mm 2 , 0.0945mm 2 , 0.1mm 2 , 0.11mm 2 or 0.12mm 2 wait.

[0166] For example, the thickness D1 of the first region 221 may be 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, or 0.8 mm.

[0167] In some embodiments, the cross-sectional area of ​​the weak section 2221 perpendicular to its extension direction is S, and the thickness of the first region 221 along the thickness direction X of the wall is D1, satisfying 0.005≤S / D1≤1.2, preferably, 0.008≤S / D1≤0.8.

[0168] Exemplarily, the ratio of the area of ​​the cross section of the weak section 2221 of the first weak portion 222 perpendicular to its extension direction to the thickness of the first region 221 can be 0.005, 0.006, 0.008, 0.01, 0.02, 0.05, 0.08, 0.1, 0.3, 0.5, 0.6, 0.8, 1 or 1.2, etc.

[0169] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to Comparative Examples 1-6 and Examples 1-6. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually merely illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0170] Comparative Example 1

[0171] 1) Preparation of positive electrode

[0172] The positive electrode active material LiNi 0.7 Co 0.1 Mn 0.1 O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are prepared into positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 50wt%, and the solid content of LiNi 0.7 Co 0.1 Mn 0.1 The mass ratio of O2, Super P and PVDF is 8:1:1. The positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil and dried at 85°C and then cold pressed. Then, it is trimmed, cut and striped, and dried under vacuum conditions at 85°C for 4 hours to make the positive electrode sheet.

[0173] 2) Preparation of negative electrode sheet

[0174] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene-butadiene rubber (SBR) were mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry was 30wt%, and the mass ratio of graphite, silicon oxide, Super P, CMC, and adhesive styrene-butadiene rubber (SBR) in the solid components was 88:7:3:2. The negative electrode slurry was coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C. Then, it was cold pressed, trimmed, cut into pieces, and slit, and then dried under vacuum conditions at 120°C for 12 hours to prepare a negative electrode sheet.

[0175] 3) Preparation of electrolyte

[0176] In an argon atmosphere glove box (H2O <0.1ppm, O2 <0.1ppm), the fully dried electrolyte salt LiPF6 was dissolved in a mixed solvent (the mixed solvent included ethylene carbonate (EC) and diethyl carbonate (DEC), and ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a mass ratio of 50:50), and after mixing evenly, a liquid electrolyte with a concentration of 1 mol / L was obtained.

[0177] 4) Isolation parts

[0178] A 16 μm polyethylene film was used as a separator.

[0179] 5) Preparation of battery cell 20

[0180] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is located between the positive and negative electrode sheets to isolate the positive and negative electrodes, and the electrode assembly 23 is wound and placed in an aluminum shell 21. The prepared electrolyte is injected into the dried shell 21, and the battery cell 20 is prepared by packaging, standing, forming, shaping, and capacity testing. The shell 21 of the battery cell 20 is a rectangular parallelepiped structure, and a pressure relief component 22 is provided on the wall 211 of the shell 21. A third groove 224 is provided on one side of the pressure relief component 22 so that the bottom of the third groove 224 forms a first area 221, and a first groove 2211 is provided on the first area 221 so that the bottom of the first groove 2211 forms at least one weak section 2221 of the first weak portion 222. The area S of the cross section of the weak section 2221 of the first weak portion 222 of the pressure relief component 22 of the battery cell 20 of comparative example 1 perpendicular to its extension direction is 0.002 mm 2 , the thickness D1 of the first region 221 in the thickness direction X of the wall is 2 mm.

[0181] The preparation methods of the battery cells 20 of Comparative Examples 2-6 and Examples 1-6 are the same as those of Comparative Example 1, except that the cross-sectional area S of the weak section 2221 of the first weak portion 222 perpendicular to its extension direction and the thickness D1 of the first region 221 in the thickness direction X of the wall are different, as shown in Table 1.

[0182] The following experiments were conducted using Comparative Examples 1-6 and Examples 1-6 to test the cross-sectional area S of the weak section 2221 of the first weak portion 222 perpendicular to its extension direction and the thickness D1 of the first region 221 under different conditions to test the number of cycle fatigue of the battery cell 20 to determine whether the pressure relief component 22 cracks prematurely under normal use and to test the timeliness of pressure relief of the battery cell 20. The specific experimental method is as follows:

[0183] 1. Experimental method and steps for testing the cycle fatigue number of the battery cell 20:

[0184] (1) Prepare a special test fixture. Specifically, the fixture consists of three 10 mm steel plates (the first steel plate, the second steel plate, and the third steel plate are arranged in sequence along the width direction Z of the wall, and the thickness directions of the first steel plate, the second steel plate, and the third steel plate are all along the width direction Z of the wall). The first steel plate and the third steel plate are located at both ends of the fixture and are fixed by bolts. The second steel plate is located between the first and third steel plates and is constrained by a guide rail so that the second steel plate can only move in translation along its thickness direction.

[0185] (2) The battery cell 20 is installed between the first steel plate and the second steel plate (i.e., the battery cell 20 is placed between the first steel plate and the second steel plate along the width direction Z of the wall), and a support structure is placed between the largest outer surface of one side of the battery cell 20 and the first steel plate, and between the largest outer surface of the other side of the battery cell 20 and the second steel plate (i.e., a support structure is placed on both sides of the battery cell 20 in the width direction Z of the wall). The support structure can be an insulation pad or a water-cooled plate (consistent with the material / structure between the battery cells 20 in the actual battery 100). The support structure can be compressed to provide expansion space for the battery cell 20 during the charge and discharge cycle aging process; the largest outer surface of one side of the battery cell 20 is in contact with the support structure, the first steel plate is in contact with the corresponding support structure, the second steel plate is in contact with the corresponding support structure, and a pressure sensor is provided between the second steel plate and the third steel plate;

[0186] (3) Adjust the position of the second steel plate by adjusting the pre-tightening force of the bolts and observing the pressure sensor so that the battery cell 20 is subjected to an initial extrusion force of 2000N, and connect the two electrode terminals 24 of the battery cell 20 to a dedicated battery charging and discharging device;

[0187] (4) Place the battery cell 20 and the fixture in a constant temperature environment of 25±2°C, and start the test after the battery cell 20 reaches temperature equilibrium;

[0188] (5) The test steps are carried out in accordance with Section 6.4 “Standard Cycle Life” of GBT31484-2015 “Requirements and Test Methods for Cycle Life of Power Batteries for Electric Vehicles”, and the test cycle end condition is changed to “stop the test until the first weak portion 222 of the pressure relief component 22 is damaged”.

[0189] Specifically, test according to the following steps:

[0190] a. Discharge to 2.8V with a current of 1I1(A);

[0191] b. Leave it for no less than 30 minutes;

[0192] c. Charge in accordance with the method 6.1.1.3 of GBT31484-2015 Cycle Life Requirements and Test Methods for Power Batteries for Electric Vehicles;

[0193] d. Leave it aside for no less than 30 minutes;

[0194] e. Discharge to 2.8V with a current of 1I1(A);

[0195] f. Repeat steps b to e until the first weak portion 222 of the pressure relief component 22 is damaged and the test is stopped.

[0196] That is, during the test process, the pressure relief component 22 of the battery cell 20 is continuously observed until the pressure relief component 22 is damaged and cracked, and the number of cycles is recorded as the cycle fatigue number of the battery cell 20. Among them, the more cycle fatigue numbers of the battery cell 20, the lower the probability of premature cracking of the pressure relief component 22 of the battery cell 20 during long-term use, and the longer the service life. Therefore, the cycle fatigue number of the battery cell 20 can be used to reasonably predict the possibility of premature cracking of the pressure relief component 22 of the battery cell 20 during use.

[0197] 2. Experimental method and steps for testing the timeliness of pressure release of the battery cell 20:

[0198] (1) Select the heating plate according to the size of the battery cell 20. The size of the heating plate should cover the largest outer surface of the battery cell 20 as much as possible (i.e., the two outer surfaces of the battery cell 20 that are opposite in the width direction Z of the wall), and the coverage area should be ≥ 60%;

[0199] (2) Before testing, charge the battery cell 20 to 100% SOC and ensure that the temperature of the battery cell 20 is 25±2°C;

[0200] (3) Sensor layout:

[0201] a. Temperature Sensing Wire Arrangement: Apply a layer of Teflon to the center of each of the two largest outer surfaces of the battery cell 20 (i.e., apply a layer of Teflon to the center of each of the two outer surfaces of the battery cell 20 that are opposite in the width direction Z of the wall). Place the temperature sensing wire above the Teflon, and then apply another layer of Teflon.

[0202] b. Layout of voltage sampling lines: Attach a layer of Teflon to the outer shell 21 of the battery cell 20 and the two electrode terminals 24, lay out the voltage sampling lines on top of the Teflon, and then attach another layer of Teflon;

[0203] c. Air pipe arrangement: Drill a hole in the wall portion 211 of the housing 21. The hole is located at the center of one side of the first groove 2211 in the length direction Y of the wall portion. That is, the hole is located on one side of the first groove 2211 in the length direction Y of the wall portion and is located between the first groove 2211 and the edge of the wall portion 211. Then, insert the air pipe into the hole and seal it. Then, connect the air pipe to the air pressure sensor.

[0204] d. Connect the temperature sensing wire, voltage sampling wire and air pressure sensor to the data acquisition instrument to collect and analyze data in real time. The acquisition frequency of the data acquisition instrument is ≤0.1 seconds;

[0205] (4) Assemble the fixture so that the fixture completely covers the largest outer surface of the battery cell 20 with a clamping force of 3000N (the arrangement order of the fixture, heating plate and battery cell 20 is: fixture + heating plate + battery cell 20 + fixture);

[0206] (5) Testing: Turn on the data acquisition instrument to collect temperature, voltage, and air pressure data, and then turn on the heating plate at a power of 500W to heat the battery cell 20 until the battery cell 20 experiences thermal runaway;

[0207] (6) Obtain the duration of the pressure holding of the battery cell 20, determine the thermal runaway moment of the battery cell 20 and the valve opening moment of the pressure relief component 22 according to the temperature, voltage and air pressure data collected by the data acquisition instrument, and obtain the duration of the pressure holding of the battery cell 20 by subtracting the thermal runaway moment of the battery cell 20 from the valve opening moment of the pressure relief component 22, so as to test the timeliness of the pressure relief of the battery cell 20 and reasonably predict the explosion or burst of the shell 21 of the battery cell 20 due to untimely pressure relief in the case of thermal runaway.

[0208] The criteria for determining thermal runaway in a battery cell 20 are as follows: (a) a voltage drop occurs at the triggering object, exceeding 25% of the initial voltage; (b) the temperature at the detection point reaches the manufacturer's maximum operating temperature; and (c) the temperature rise rate dT / dt at the detection point is ≥ 1°C / s and persists for more than 3 seconds. When (a) and (c) or (b) and (c) are met, thermal runaway is determined for the battery cell 20, and the moment of thermal runaway is determined.

[0209] Determination of the valve opening time of the pressure relief component 22: When the air pressure drops by more than 25%, it can be determined that the pressure relief component 22 has been opened. Therefore, the moment when the air pressure begins to drop is the valve opening time of the pressure relief component 22.

[0210] The experimental results of Comparative Examples 1-6 and Examples 1-6 are shown in Table 1 below.

[0211] Table 1

[0212] As shown in Table 1, based on the experimental results of Comparative Examples 1-6 and Examples 1-6, it can be seen that the thickness of the first region 221 is set to be greater than or equal to 0.8 mm, and the area of ​​the cross section of the weak section 2221 of the first weak portion 222 perpendicular to its extension direction is less than or equal to 0.008 mm. 2 When the battery cell 20 is subjected to fatigue cycles of only 1034 times, the pressure relief component 22 is very likely to crack prematurely during use, thereby shortening the service life of the battery cell 20 during use. The thickness of the first region 221 is set to be less than or equal to 0.8 mm, and the cross-sectional area of ​​the weak section 2221 of the first weak portion 222 perpendicular to its extension direction is greater than or equal to 0.008 mm. 2 When the battery cell 20 is subjected to the fatigue test, the number of cycle fatigue times can reach more than 1500 times, thereby reducing the phenomenon of premature cracking of the pressure relief component 22 during use, which is beneficial to improving the service life of the battery cell 20. Therefore, the ratio of the area of ​​the cross section of the weak section 2221 of the first weak portion 222 perpendicular to its extension direction to the thickness of the first region 221 is set to be greater than or equal to 0.005.

[0213] Similarly, the thickness of the first region 221 is less than or equal to 0.2 mm, and the cross-sectional area of ​​the weak section 2221 of the first weak portion 222 perpendicular to its extension direction is greater than or equal to 0.12 mm. 2When the battery cell 20 is held in air for more than 5 seconds, the pressure relief component 22 of the battery cell 20 requires a high burst pressure when the battery cell 20 is in thermal runaway. The pressure relief component 22 cannot release pressure in time, resulting in a high risk of explosion or rupture of the outer shell 21 of the battery cell 20 in thermal runaway, thereby resulting in low reliability of the battery cell 20. The thickness of the first region 221 is greater than or equal to 0.2 mm, and the area of ​​the cross section of the weak section 2221 of the first weak portion 222 perpendicular to its extension direction is less than or equal to 0.12 mm. 2 , the holding time of the battery cell 20 can reach less than 5 seconds, which is beneficial to reducing the bursting pressure required for the battery cell 20 to relieve pressure, thereby reducing the risk of bursting or explosion of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, and thus effectively improving the reliability of the battery cell 20. Therefore, the ratio of the area of ​​the cross-section of the weak section 2221 of the first weak portion 222 perpendicular to its extension direction to the thickness of the first region 221 is set to be less than or equal to 1.2, so that it can not only alleviate the phenomenon of premature cracking of the pressure relief component 22 of the battery cell 20 during use, but also reduce the risk of bursting or explosion of the battery cell 20 during the pressure relief process.

[0214] In this embodiment, the thickness of the first region 221 is set to 0.2 mm to 0.8 mm. Correspondingly, the cross-sectional area of ​​the weak section 2221 of the first weak portion 222 perpendicular to its extension direction is set to 0.008 mm. 2 to 0.12mm 2 On the one hand, by setting the thickness of the first region 221 to be less than or equal to 0.8 mm, and setting the cross-sectional area of ​​the weak section 2221 of the first weak portion 222 perpendicular to its extension direction to be greater than or equal to 0.008 mm 2 , so as to reduce the concentration of stress generated by the expansion of the battery cell 20 in the weak section 2221 of the first weak portion 222, and improve the absorption effect of the first area 221 on stress, thereby effectively alleviating the phenomenon of tensile deformation of the weak section 2221 of the first weak portion 222 of the pressure relief component 22, thereby reducing the strain and strain amplitude of the first weak portion 222 of the pressure relief component 22, and further reducing the phenomenon of structural strength reduction of the first weak portion 222 of the pressure relief component 22 due to excessive strain and strain amplitude, thereby improving the use stability of the pressure relief component 22, and alleviating the phenomenon of premature cracking of the pressure relief component 22 during use, which is beneficial to improving the service life of the battery cell 20. On the other hand, by setting the thickness of the first area 221 to be greater than or equal to 0.2 mm, and setting the area of ​​the cross section of the weak section 2221 of the first weak portion 222 perpendicular to its extension direction to be less than or equal to 0.12 mm 2, so as to reduce the bursting pressure required by the pressure relief component 22 during pressure relief, thereby improving the timeliness of pressure relief of the pressure relief component 22, so as to improve the reliability of the battery cell 20 during thermal runaway, and further help to reduce the risk of bursting or explosion of the battery cell 20 during thermal runaway, so that while taking into account the improvement of the service life of the battery cell 20, it can also effectively improve the reliability of the battery cell 20.

[0215] According to some embodiments of the present application, referring to FIG. 5 , FIG. 7 and FIG. 8 , a first groove 2211 is provided on the first region 221 , and at least one weak section 2221 is formed at the bottom of the first groove 2211 .

[0216] In which, at least one weak section 2221 is formed at the bottom of the first groove 2211, that is, the first area 221 is provided with a position of the first groove 2211 and the area corresponding to the bottom surface of the first groove 2211 is at least one weak section 2221 of the first weak portion 222, so that the weak section 2221 of the first weak portion 222 is the residual part of the first area 221 at the first groove 2211.

[0217] It should be noted that, in other embodiments, the first weak portion 222 may also be other structures. For example, the first weak portion 222 may be formed by partially heat treating the first region 221 to weaken the local structural strength of the first region 221 .

[0218] In some embodiments, along the thickness direction X of the wall portion, the maximum groove depth of the first groove 2211 is greater than or equal to 0.4 mm and less than or equal to 2 mm.

[0219] Along the thickness direction X of the wall, the maximum groove depth of the first groove 2211 can be any one of 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm, 1.55mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm, 1.8mm, 1.85mm, 1.9mm, 1.95mm, 2mm, etc., or a range value between any two of them.

[0220] In this embodiment, by providing a first groove 2211 on the first area 221, at least one weak section 2221 of the first weak portion 222 is formed in the area of ​​the first area 221 where the first groove 2211 is provided and corresponding to the bottom surface of the first groove 2211. The battery cell 20 adopting this structure facilitates the formation of the weak section 2221 of the first weak portion 222 on the first area 221 of the pressure relief component 22, which is beneficial to reducing the difficulty of forming the first weak portion 222 on the first area 221, thereby improving the production efficiency of the battery cell 20.

[0221] According to some embodiments of the present application, referring to Figures 6 and 7, the maximum width of the weak section 2221 is W, and the minimum thickness of the weak section 2221 along the thickness direction X of the wall is D2. The product of the maximum width W of the weak section 2221 and the minimum thickness D2 of the weak section 2221 is the area S of the cross section of the weak section 2221 perpendicular to its extension direction, that is, S = W × D2, satisfying 0.1mm≤W≤0.3mm, 0.08mm≤D2≤0.4mm.

[0222] The maximum width of the weak section 2221 is W, that is, the maximum width of the bottom surface of the first groove 2211 is W. For example, in FIG7 , the bottom surface of the first groove 2211 and the groove side surface of the first groove 2211 are connected by a circular arc chamfered surface, that is, a circular arc chamfer is formed between the bottom surface of the first groove 2211 and the groove side surface of the first groove 2211, then the maximum width W of the weak section 2221 is only the width of the bottom surface of the first groove 2211.

[0223] The minimum thickness of the weak section 2221 is D2, i.e., the residual thickness of the first region 221 at the first groove 2211 along the wall thickness direction X. In other words, the minimum thickness of the bottom wall of the first groove 2211 along the wall thickness direction X is D2. Correspondingly, the minimum thickness of the region of the pressure relief component 22 corresponding to the bottom surface of the first groove 2211 along the wall thickness direction X is D2.

[0224] Illustratively, the maximum width W of the weak section 2221 may be 0.1 mm, 0.11 mm, 0.13 mm, 0.15 mm, 0.16 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.24 mm, 0.25 mm, 0.27 mm, 0.29 mm or 0.3 mm, etc.

[0225] Illustratively, the minimum thickness D2 of the weak section 2221 may be 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.16 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.24 mm, 0.25 mm, 0.28 mm, 0.3 mm, 0.32 mm, 0.35 mm, 0.38 mm or 0.4 mm, etc.

[0226] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to Examples 7-14. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of this application.

[0227] The preparation methods of the battery cells 20 of Examples 7-14 are the same as those of Comparative Example 1. The difference between the battery cells 20 of Examples 7-14 lies in the difference in the maximum width W and the minimum thickness D2 of the weak section 2221 , as shown in Table 2.

[0228] Below, through Examples 7-14, experiments are conducted on the maximum width W of the weak section 2221 and the minimum thickness D2 of the weak section 2221 under different conditions to test the number of cycle fatigue of the battery cell 20 to obtain the situation where the pressure relief component 22 cracks prematurely under normal use, and to test the timeliness of pressure relief of the battery cell 20. It should be noted that the experimental methods and steps for the number of cycle fatigue of the battery cell 20 in Examples 7-14 can refer to the experimental methods and steps for the number of cycle fatigue of the battery cell 20 in the above-mentioned comparative examples 1-6 and Examples 1-6. Similarly, the experimental methods and steps for the timeliness of pressure relief of the battery cell 20 in Examples 7-14 can refer to the experimental methods and steps for the timeliness of pressure relief of the battery cell 20 in the above-mentioned comparative examples 1-6 and Examples 1-6, and will not be repeated here.

[0229] The experimental results of Examples 7-14 are shown in Table 2 below.

[0230] Table 2

[0231] As shown in Table 2, based on the experimental results of Examples 7-14 and the experimental results of Comparative Examples 1-6 and Examples 1-6 in Table 1, when the maximum width of the weak section 2221 is greater than or equal to 0.1 mm and the minimum thickness of the weak section 2221 is greater than or equal to 0.08 mm, the number of cycle fatigue times of the battery cell 20 can reach more than 1,600 times, thereby further alleviating the phenomenon of premature cracking of the pressure relief component 22 during use, which is beneficial to further improve the service life of the battery cell 20. Therefore, the maximum width of the weak section 2221 is set to be greater than or equal to 0.1 mm, and the minimum thickness of the weak section 2221 is set to be greater than or equal to 0.08 mm.

[0232] Similarly, when the maximum width of the weak section 2221 is less than or equal to 0.3 mm and the minimum thickness of the weak section 2221 is less than or equal to 0.4 mm, the holding time of the battery cell 20 can reach less than 4.5 seconds, which is beneficial to further reduce the bursting pressure required for the battery cell 20 to relieve pressure, thereby reducing the risk of bursting or explosion of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, and thus effectively improving the reliability of the battery cell 20. Therefore, the maximum width of the weak section 2221 is set to less than or equal to 0.3 mm, and the minimum thickness of the weak section 2221 is set to less than or equal to 0.4 mm.

[0233] In this embodiment, the area S of the cross section of the weak section 2221 of the first weak portion 222 perpendicular to its extension direction is the product of the minimum thickness D2 of the weak section 2221 and the maximum width W of the weak section 2221. The maximum width of the weak section 2221 is set to 0.1 mm to 0.3 mm, and correspondingly, the minimum thickness of the weak section 2221 is set to 0.08 mm to 0.4 mm. On the one hand, by setting the maximum width of the weak section 2221 to be greater than or equal to 0.1 mm and the minimum thickness of the weak section 2221 to be greater than or equal to 0.08 mm, the concentration of the stress generated by the expansion of the battery cell 20 in the weak section 2221 of the first weak portion 222 can be further reduced, and the first region 221 can be further improved. The stress absorption effect can further reduce the strain and strain amplitude of the first weak portion 222 of the pressure relief component 22, thereby further alleviating the phenomenon of premature cracking of the pressure relief component 22 during use, so as to further improve the service life of the battery cell 20. On the other hand, by setting the maximum width of the weak section 2221 to less than or equal to 0.3 mm, and setting the minimum thickness of the weak section 2221 to less than or equal to 0.4 mm, the bursting pressure required by the pressure relief component 22 during pressure relief can be further reduced, thereby further improving the timeliness of pressure relief of the pressure relief component 22, and further improving the reliability of the battery cell 20 during thermal runaway, which is conducive to further reducing the risk of bursting or explosion of the battery cell 20 during thermal runaway.

[0234] According to some embodiments of the present application, as shown in FIG. 7 , the maximum width of the weak section 2221 is W, satisfying 0.16 mm ≤ W ≤ 0.24 mm.

[0235] Among them, please continue to refer to Table 2. Based on the experimental results of Examples 7-14, it can be seen that when the maximum width of the weak section 2221 is greater than or equal to 0.16 mm, the number of cycle fatigue times of the battery cell 20 can reach more than 1,800 times, thereby further alleviating the phenomenon of premature cracking of the pressure relief component 22 during use, which is beneficial to improving the service life of the battery cell 20. Therefore, the maximum width of the weak section 2221 is set to be greater than or equal to 0.16 mm.

[0236] In this embodiment, by further setting the maximum width of the weak section 2221 to be greater than or equal to 0.16 mm, the pressure relief component 22 is further protected from premature cracking during use, thereby improving the service life of the battery cell 20 and reducing the difficulty in processing the first groove 2211. By further setting the maximum width of the weak section 2221 to be less than or equal to 0.24 mm, the problem of the first groove 2211 occupying too much space is alleviated.

[0237] According to some embodiments of the present application, please continue to refer to FIG. 7 , the minimum thickness of the weak section 2221 is D2, which satisfies 0.12 mm ≤ D2 ≤ 0.3 mm.

[0238] Among them, please continue to refer to Table 2. Based on the experimental results of Examples 7-14, it can be seen that when the minimum thickness of the weak section 2221 is less than or equal to 0.3 mm, the holding time of the battery cell 20 can reach less than 4 seconds, which is beneficial to further reduce the bursting pressure required for the battery cell 20 to relieve pressure, thereby further reducing the risk of bursting or explosion of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, and thus effectively improving the reliability of the battery cell 20. Therefore, the minimum thickness of the weak section 2221 is set to be less than or equal to 0.3 mm.

[0239] In this embodiment, the minimum thickness of the weak section 2221 is further set to be greater than or equal to 0.12 mm, thereby further reducing the difficulty in processing the first groove 2211. By further setting the minimum thickness of the weak section 2221 to be less than or equal to 0.13 mm, the timely pressure relief of the pressure relief component 22 is further improved, thereby improving the reliability of the battery cell 20 during thermal runaway, and further reducing the risk of bursting or explosion of the battery cell 20 during thermal runaway.

[0240] According to some embodiments of the present application, as shown in Figures 4, 5, and 8, along the thickness direction X of the wall portion, the first groove 2211 is provided on a side of the first region 221 facing away from the interior of the housing 21. In other words, the first groove 2211 is provided on a surface of the first region 221 of the pressure relief component 22 facing away from the electrode assembly 23.

[0241] In this embodiment, by arranging the first groove 2211 on the outer surface of the first area 221 away from the interior of the shell 21, it is convenient to form the first groove 2211 on the first area 221, which is beneficial to reduce the processing difficulty of the first groove 2211 and improve the production efficiency of the battery cell 20.

[0242] According to some embodiments of the present application, with reference to FIG8 , and further with reference to FIG9 , FIG10 and FIG11 , FIG9 is a bottom view of the shell 212 of the outer shell 21 of the battery cell 20 provided in some embodiments of the present application, FIG10 is a partial cross-sectional view of the wall portion 211 of the outer shell 21 of the battery cell 20 provided in some embodiments of the present application, and FIG11 is a partial enlarged view of the wall portion 211 of the outer shell 21 of the battery cell 20 shown in FIG10 at point B. The first groove 2211 includes a plurality of grooves arranged in sequence along the thickness direction X of the wall portion. In other words, the first groove 2211 is a multi-step groove structure arranged along the thickness direction X of the wall portion, that is, the first groove 2211 is a stepped groove structure formed by multiple stamping operations.

[0243] For example, in FIG11 , the first groove 2211 is a three-step groove structure. Of course, in other embodiments, the first groove 2211 may also be a two-step groove, a four-step groove, a five-step groove, or a six-step groove.

[0244] It should be noted that, in embodiments where the first groove 2211 includes multiple groove segments, each groove segment is a multi-step groove structure. For example, in Figures 8 and 9, the first groove 2211 includes a first groove segment 2211a, a second groove segment 2211b, and a third groove segment 2211c. Accordingly, the first groove segment 2211a, the second groove segment 2211b, and the third groove segment 2211c are all multi-step groove structures. Of course, if the first groove 2211 is a structure such as a curve, a loop, or a straight line extending along a smooth trajectory, the first groove 2211 is a multi-step groove structure. For example, as shown in Figure 5, the first groove 2211 is an annular structure. Accordingly, the first groove 2211 is a multi-step groove structure.

[0245] In this embodiment, the first groove 2211 is set as a stepped groove structure arranged along the thickness direction X of the wall portion, so that the first groove 2211 is a groove formed by multiple processing. The first groove 2211 with this structure can, under the condition of the same depth, reduce the depth of the first groove 2211 processed in a single time, which is beneficial to reducing the manufacturing difficulty of the first groove 2211 and the demand for manufacturing equipment, so as to reduce the manufacturing cost, and can reduce the forming force applied to the first area 221 during the single processing of the first groove 2211, which is beneficial to reducing the risk of cracks in the first area 221, so as to improve the production quality of the battery cell 20. On the other hand, it can improve the flow morphology of the first groove 2211 during the formation process, which is beneficial to the flow of the material generated when the first groove 2211 is formed, so as to improve the structural consistency of the first groove 2211.

[0246] According to some embodiments of the present application, referring to FIG. 4 , FIG. 5 and FIG. 6 , the first groove 2211 is an annular groove connected end to end, and the bottom of the first groove 2211 forms a weak section 2221 of an annular structure.

[0247] Among them, the first groove 2211 is an annular groove connected from end to end, that is, the first groove 2211 only includes a groove section of an annular structure extending along a smooth trajectory. Correspondingly, the first area 221 corresponds to the part of the groove bottom surface of the first groove 2211 to form a weak section 2221 of the first weak section 222, and the first weak section 222 as a whole only includes one weak section 2221, that is, the first weak section 222 as a whole is a weak section 2221, and the weak section 2221 is an annular structure.

[0248] In this embodiment, by setting the first groove 2211 as an annular structure connected end to end, on the one hand, the difficulty of processing and forming the first groove 2211 on the first area 221 can be reduced; on the other hand, when the battery cell 20 is depressurized, the area within the first groove 2211 of the annular structure can be completely detached, which is beneficial to increasing the pressure relief area of ​​the battery cell 20.

[0249] According to some embodiments of the present application, referring to FIG12 , FIG12 is a bottom view of the housing 212 of the outer shell 21 of the battery cell 20 provided in still further embodiments of the present application. The first groove 2211 includes a first groove section 2211a and a second groove section 2211b . The first groove section 2211a is connected to the second groove section 2211b . The bottom of the first groove section 2211a and the bottom of the second groove section 2211b both form a weak section 2221 . The first groove section 2211a and the second groove section 2211b together define a predetermined pressure relief area 2212 . The predetermined pressure relief area 2212 is configured to be opened when the pressure relief component 22 is ruptured along at least a portion of the first weak section 222 to relieve the internal pressure of the battery cell 20 .

[0250] Among them, the bottom of the first groove section 2211a and the bottom of the second groove section 2211b both form weak sections 2221, that is, the first weak portion 222 includes two weak sections 2221, and the two weak sections 2221 are respectively the part of the groove bottom surface of the first groove section 2211a corresponding to the first groove section 2211a in the first area 221 and the part of the groove bottom surface of the second groove section 2211b corresponding to the first area 221. The two weak sections 2221 are interconnected to form the first weak portion 222.

[0251] The first slot section 2211a and the second slot section 2211b jointly define a predetermined pressure relief area 2212 , that is, the first slot section 2211a and the second slot section 2211b are structures arranged along the edge of the predetermined pressure relief area 2212 , so that the setting trajectory of the first groove 2211 is arranged along the edge of the predetermined pressure relief area 2212 .

[0252] The predetermined pressure relief area 2212 is configured to be able to be opened when the pressure relief component 22 is cracked along at least a portion of the first weak portion 222, that is, when the battery cell 20 undergoes thermal runaway and releases internal pressure, the area where the first groove section 2211a and the second groove section 2211b are set in the first area 221 of the pressure relief component 22 can be cracked, so that the predetermined pressure relief area 2212 can be opened and the internal pressure of the battery cell 20 can be released.

[0253] 12 , one end of the first slot segment 2211a is connected to one end of the second slot segment 2211b, so that the first slot segment 2211a and the second slot segment 2211b form a "V"-shaped first groove 2211. Of course, in other embodiments, the shape of the first groove 2211 formed by the interconnection of the first slot segment 2211a and the second slot segment 2211b may also be a "T"-shaped structure, an "L"-shaped structure, an "X"-shaped structure, or the like.

[0254] It should be noted that, in the embodiment where the first groove 2211 is a multi-stage groove, the first groove section 2211 a and the second groove section 2211 b both have a multi-stage groove structure.

[0255] In this embodiment, the first groove 2211 is provided with a first groove section 2211a and a second groove section 2211b, and the first groove section 2211a and the second groove section 2211b are interconnected structures, so that the first groove section 2211a and the second groove section 2211b jointly define a predetermined pressure relief area 2212. On the one hand, it can increase the pressure relief area of ​​the battery cell 20 to increase the pressure relief rate of the battery cell 20. On the other hand, it makes the position where the first groove section 2211a and the second groove section 2211b are interconnected weaker, and it is easier to crack and open the predetermined pressure relief area 2212 to release the internal pressure of the battery cell 20.

[0256] According to some embodiments of the present application, referring to Figures 8, 9 and 10, the first groove 2211 includes a first groove section 2211a, a second groove section 2211b and a third groove section 2211c. The bottom of the first groove section 2211a, the bottom of the second groove section 2211b and the bottom of the third groove section 2211c all form a weak section 2221. The first groove section 2211a and the third groove section 2211c are arranged opposite to each other, and the second groove section 2211b connects the first groove section 2211a and the third groove section 2211c. The first groove section 2211a, the second groove section 2211b and the third groove section 2211c jointly define a predetermined pressure relief area 2212. The predetermined pressure relief area 2212 is configured to be able to be opened when the pressure relief component 22 is cracked along at least a portion of the first weak portion 222 to release the internal pressure of the battery cell 20.

[0257] Among them, the bottom of the first groove segment 2211a, the bottom of the second groove segment 2211b and the bottom of the third groove segment 2211c all form weak sections 2221, that is, the first weak portion 222 includes three weak sections 2221, and the three weak sections 2221 are respectively the part of the groove bottom surface of the first groove segment 2211a corresponding to the first area 221, the part of the groove bottom surface of the second groove segment 2211b corresponding to the first area 221, and the part of the groove bottom surface of the third groove segment 2211c corresponding to the first area 221. The three weak sections 2221 constitute the first weak portion 222.

[0258] The first slot section 2211a and the third slot section 2211c are arranged opposite each other, that is, the first slot section 2211a and the third slot section 2211c are spaced apart. For example, in FIG9 , the first slot section 2211a and the third slot section 2211c are spaced apart along the length direction Y of the wall portion, and both the first slot section 2211a and the third slot section 2211c extend along the width direction Z of the wall portion.

[0259] The second slot segment 2211b connects the first slot segment 2211a and the third slot segment 2211c. That is, the second slot segment 2211b is located between the first slot segment 2211a and the third slot segment 2211c, and the two ends of the second slot segment 2211b are respectively connected to the first slot segment 2211a and the third slot segment 2211c. For example, in FIG9 , the second slot segment 2211b extends along the longitudinal direction Y of the wall portion. Of course, in other embodiments, the second slot segment 2211b may also extend from the first slot segment 2211a and the third slot segment 2211c at its two ends in the longitudinal direction Y of the wall portion.

[0260] The first slot section 2211a, the second slot section 2211b and the third slot section 2211c jointly define a predetermined pressure relief area 2212. That is, the first slot section 2211a, the second slot section 2211b and the third slot section 2211c can enclose at least one predetermined pressure relief area 2212 on the first area 221, and the first slot section 2211a, the second slot section 2211b and the third slot section 2211c are structures arranged along the edge of the predetermined pressure relief area 2212, so that the predetermined pressure relief area 2212 can be formed by the first slot section 2211a, the second slot section 2211b and the third slot section 2211c. The groove section 2211a, the second groove section 2211b and the third groove section 2211c are opened as boundaries, that is, a predetermined pressure relief area 2212 is formed in the area enclosed by the first groove section 2211a, the second groove section 2211b and the third groove section 2211c, so that the part of the first area 221 located in the predetermined pressure relief area 2212 can be opened with the first groove section 2211a, the second groove section 2211b and the third groove section 2211c as boundaries when the battery cell 20 is depressurized, thereby releasing the internal pressure of the battery cell 20.

[0261] Alternatively, in FIG9 , the first groove 2211 formed by the first groove section 2211a, the second groove section 2211b, and the third groove section 2211c may be in an H-shaped configuration, thereby forming two predetermined pressure relief zones 2212 on the first region 221, with the two predetermined pressure relief zones 2212 located on either side of the second groove section 2211b. Of course, the first groove 2211 may also have other configurations. Referring to FIG13 , FIG13 is a bottom view of the housing 212 of the outer shell 21 of the battery cell 20 provided in other embodiments of the present application. The first groove 2211 formed by the first groove section 2211a, the second groove section 2211b, and the third groove section 2211c may be in a U-shaped configuration, where one end of the second groove section 2211b is connected to one end of the first groove section 2211a, and the other end is connected to one end of the third groove section 2211c, thereby forming a predetermined pressure relief zone 2212 on the first region 221.

[0262] It should be noted that, in the embodiment where the first groove 2211 is a multi-stage groove, the first groove section 2211a, the second groove section 2211b and the third groove section 2211c are all multi-stage groove structures.

[0263] In this embodiment, the first groove 2211 is provided with a first groove section 2211a and a third groove section 2211c that are relatively arranged, and a second groove section 2211b connecting the first groove section 2211a and the third groove section 2211c, so that the pressure relief component 22 can split along the first groove section 2211a, the second groove section 2211b and the third groove section 2211c when the battery cell 20 releases pressure, so as to open the predetermined pressure relief area 2212 to release the internal pressure of the battery cell 20. The first groove 2211 with such a structure makes the intersection position of the first groove section 2211a and the second groove section 2211b and the intersection position of the second groove section 2211b and the third groove section 2211c weaker, easier to split and open the predetermined pressure relief area 2212 for pressure relief, and can further improve the pressure relief area and pressure relief rate of the battery cell 20.

[0264] In some embodiments, referring to Figures 8 and 9, the connection position of the first slot segment 2211a and the second slot segment 2211b deviates from the two ends of the first slot segment 2211a, and the connection position of the third slot segment 2211c and the second slot segment 2211b deviates from the two ends of the third slot segment 2211c, so that predetermined pressure relief areas 2212 are formed on both sides of the second slot segment 2211b.

[0265] Among them, the connection position of the first slot segment 2211a and the second slot segment 2211b deviates from the two ends of the first slot segment 2211a, that is, the second slot segment 2211b is connected between the two ends of the first slot segment 2211a. Similarly, the connection position of the third slot segment 2211c and the second slot segment 2211b deviates from the two ends of the third slot segment 2211c, that is, the second slot segment 2211b is connected between the two ends of the third slot segment 2211c, so that the shape of the first groove 2211 formed by the first slot segment 2211a, the second slot segment 2211b and the third slot segment 2211c is an approximately "H"-shaped structure.

[0266] In this embodiment, by setting the connection position of the first groove section 2211a and the second groove section 2211b to be located between the two ends of the first groove section 2211a, and setting the connection position of the third groove section 2211c and the second groove section 2211b to be located between the two ends of the third groove section 2211c, the first groove section 2211a, the second groove section 2211b and the third groove section 2211c form an "H"-shaped structure, so that predetermined pressure relief areas 2212 can be formed on both sides of the second groove section 2211b of the first groove 2211, and the two predetermined pressure relief areas 2212 can be opened in a split manner for pressure relief when the battery cell 20 is relieved of pressure, which is beneficial to further increase the pressure relief effect of the battery cell 20 and can effectively improve the pressure relief rate of the battery cell 20.

[0267] In some embodiments, referring to Figures 8 and 9 , the first slot segment 2211a, the second slot segment 2211b, and the third slot segment 2211c all extend along straight lines, and the first slot segment 2211a and the third slot segment 2211c are both perpendicular to the second slot segment 2211b. In other words, the extension direction of the second slot segment 2211b is perpendicular to the extension direction of the first slot segment 2211a and the extension direction of the third slot segment 2211c, so that the first groove 2211 formed by the first slot segment 2211a, the second slot segment 2211b, and the third slot segment 2211c form a regular "H"-shaped structure, and predetermined pressure relief areas 2212 are formed on both sides of the second slot segment 2211b. The areas of the two predetermined pressure relief areas 2212 may be the same or different.

[0268] Exemplarily, the second slot segment 2211b is a straight structure extending along the length direction Y of the wall portion, the first slot segment 2211a and the third slot segment 2211c are both straight structures extending along the width direction Z of the wall portion, and the second slot segment 2211b is located between the first slot segment 2211a and the third slot segment 2211c along the length direction Y of the wall portion.

[0269] In this embodiment, by setting the first slot section 2211a, the second slot section 2211b and the third slot section 2211c to extend along a straight line, and setting the first slot section 2211a and the third slot section 2211c to be perpendicular to the second slot section 2211b, so that the extension direction of the second slot section 2211b is the arrangement direction of the first slot section 2211a and the third slot section 2211c, on the one hand, the regularity of the shape of the first groove 2211 can be improved, which is conducive to reducing the processing difficulty of the first groove 2211, thereby reducing the manufacturing cost of the battery cell 20. On the other hand, the two predetermined pressure relief areas 2212 located on both sides of the second slot section 2211b relieve pressure in opposite directions when the battery cell 20 is relieved.

[0270] According to some embodiments of the present application, referring to FIG14 , FIG14 is a bottom view of the shell 212 of the outer shell 21 of the battery cell 20 provided in still other embodiments of the present application, and the first slot segment 2211a , the second slot segment 2211b and the third slot segment 2211c all extend along an arc trajectory.

[0271] For example, in Figure 14, the two ends of the second slot segment 2211b are respectively connected to one end of the first slot segment 2211a and one end of the third slot segment 2211c, and the first slot segment 2211a, the second slot segment 2211b and the third slot segment 2211c all extend along an arc trajectory, so that the first slot segment 2211a, the second slot segment 2211b and the third slot segment 2211c form a first groove 2211 having a "C"-shaped structure.

[0272] In this embodiment, by setting the first groove section 2211a, the second groove section 2211b and the third groove section 2211c as structures extending along an arc trajectory, it is beneficial to improve the arc degree of the connection position of the first groove section 2211a and the second groove section 2211b, and the arc degree of the connection position of the second groove section 2211b and the third groove section 2211c. On the one hand, it can reduce the difficulty of processing the first groove 2211, and on the other hand, it can facilitate the first area 221 of the pressure relief component 22 to open the predetermined pressure relief area 2212 after it is split along the first groove section 2211a, the second groove section 2211b and the third groove section 2211c to release the internal pressure of the battery cell 20.

[0273] According to some embodiments of the present application, as shown in Figure 9, the first groove 2211 may further include a fourth groove section 2211d, the bottom of the fourth groove section 2211d forms a weak section 2221, the fourth groove section 2211d is located between the first groove section 2211a and the third groove section 2211c, and the fourth groove section 2211d is connected to the second groove section 2211b.

[0274] The bottom of the fourth groove segment 2211 d forms a weak segment 2221 , that is, the portion of the first region 221 corresponding to the bottom surface of the fourth groove segment 2211 d also forms a weak segment 2221 , so that the first weak portion 222 includes four weak segments 2221 .

[0275] Illustratively, the fourth slot segment 2211d extends along the width direction Z of the wall portion, and the fourth slot segment 2211d and the second slot segment 2211b are perpendicular to each other.

[0276] Illustratively, the distance between the fourth slot segment 2211d and the first slot segment 2211a in the length direction Y of the wall is equal to the distance between the fourth slot segment 2211d and the third slot segment 2211c in the length direction Y of the wall.

[0277] It should be noted that, in the embodiment where the first groove 2211 is a multi-stage groove, the fourth groove segment 2211 d also has a multi-stage groove structure.

[0278] In this embodiment, the first groove 2211 is further provided with a fourth groove section 2211d located between the first groove section 2211a and the third groove section 2211c, and the fourth groove section 2211d is interconnected with the second groove section 2211b, so that the stress at the position where the fourth groove section 2211d and the second groove section 2211b are interconnected is more concentrated and easier to rupture, so that the pressure relief component 22 ruptures along the second groove section 2211b from the intersection of the second groove section 2211b and the fourth groove section 2211d during the pressure relief process, and ruptures along the first groove section 2211a and the third groove section 2211c after the second groove section 2211b ruptures, so as to achieve rapid pressure relief.

[0279] According to some embodiments of the present application, referring to Figures 9 and 10 as well as Figures 12, 13 and 14, the first region 221 is further formed with a second weak portion 223. Along the thickness direction X of the wall portion, the thickness of the second weak portion 223 is greater than the thickness of the first weak portion 222. The second weak portion 223 is configured to guide the predetermined pressure relief zone 2212 to flip when the first weak portion 222 is cracked, so as to release the internal pressure of the battery cell 20.

[0280] Among them, the second weak portion 223 is configured to guide the predetermined pressure relief area 2212 to flip when the first weak portion 222 is broken, that is, the predetermined pressure relief area 2212 can flip with the second weak portion 223 as the axis after the first weak portion 222 in the first area 221 is broken, so that after the predetermined pressure relief area 2212 is flipped, the inside of the shell 21 and the outside of the shell 21 are connected to each other and pressure relief is performed.

[0281] In this embodiment, the first area 221 is further provided with a second weak portion 223, and the thickness of the second weak portion 223 is greater than the thickness of the first weak portion 222, so that the pressure relief component 22 can preferentially split along the first weak portion 222 and open the predetermined pressure relief area 2212, and the predetermined pressure relief area 2212 can be flipped around the second weak portion 223 as the axis when being opened, thereby improving the opening effect of the predetermined pressure relief area 2212 of the pressure relief component 22, which is beneficial to increasing the pressure relief area of ​​the battery cell 20 after the predetermined pressure relief area 2212 is opened, and further improving the pressure relief rate of the battery cell 20 when thermal runaway occurs, so as to reduce the risk of fire, explosion or connection failure of the battery cell 20 due to untimely pressure relief, which is beneficial to improving the reliability of the battery cell 20.

[0282] In some embodiments, please continue to refer to FIG. 9 and FIG. 10 as well as FIG. 12 , FIG. 13 and FIG. 14 , the first region 221 is provided with a second groove 2213 , and the bottom of the second groove 2213 forms a second weak portion 223 .

[0283] The bottom of the second groove 2213 forms the second weak portion 223. That is, the portion of the second region where the second groove 2213 is located and corresponding to the bottom surface of the second groove 2213 constitutes the second weak portion 223. Of course, in other embodiments, the second weak portion 223 may also have other structures. For example, the second weak portion 223 may be formed by heat treating a portion of the first region 221 to weaken the strength of that region.

[0284] In this embodiment, a second groove 2213 is provided on the first area 221, so that the first area 221 forms a second weak portion 223 in the area where the second groove 2213 is provided and corresponding to the bottom surface of the second groove 2213. The battery cell 20 adopting this structure facilitates the formation of the second weak portion 223 on the first area 221 of the pressure relief component 22, which is beneficial to reducing the difficulty of forming the second weak portion 223 on the first area 221, thereby improving the production efficiency of the battery cell 20.

[0285] According to some embodiments of the present application, as shown in FIG. 9 and FIG. 10 , along the thickness direction X of the wall, the second groove 2213 is provided on a side of the first region 221 facing the interior of the housing 21 .

[0286] The second groove 2213 is provided on the side of the first region 221 facing the interior of the housing 21, that is, the second groove 2213 is provided on the surface of the first region 221 facing the electrode assembly 23. Of course, in other embodiments, the second groove 2213 can also be provided on the side of the first region 221 facing away from the electrode assembly 23.

[0287] 9 , the second groove 2213 is a strip-shaped structure and is parallel to the second groove section 2211 b , so that the second weak portion 223 is a strip-shaped structure, thereby facilitating the predetermined pressure relief area 2212 to flip around the second weak portion 223 after being opened.

[0288] In this embodiment, the second groove 2213 is arranged on the surface of the first area 221 facing the interior of the shell 21, so that the predetermined pressure relief zone 2212 can be flipped toward the outside of the shell 21 around the bottom wall of the second groove 2213 when it is opened, thereby reducing the interference effect of the groove side surface of the second groove 2213 on the predetermined pressure relief zone 2212 during the flipping process, which is conducive to improving the flipping effect of the predetermined pressure relief zone 2212.

[0289] According to some embodiments of the present application, as shown in FIG. 8 , FIG. 9 and FIG. 10 , along the thickness direction X of the wall, the first groove 2211 and the second groove 2213 are respectively provided on both sides of the first region 221 .

[0290] Exemplarily, the first groove 2211 is arranged on the surface of the first area 221 facing away from the interior of the shell 21, and the second groove 2213 is arranged on the surface of the first area 221 facing the interior of the shell 21, so that the first groove 2211 and the second groove 2213 are respectively arranged on both sides of the first area 221.

[0291] In this embodiment, by arranging the first groove 2211 and the second groove 2213 on both sides of the first area 221 respectively, it is convenient to process the first groove 2211 and the second groove 2213 on both sides of the first area 221 respectively, which is beneficial to reduce the mutual influence between the first groove 2211 and the second groove 2213 during the processing.

[0292] According to some embodiments of the present application, as shown in Figures 9 and 10 as well as Figures 12, 13, and 14, along the thickness direction X of the wall portion, the projection of the first groove 2211 and the projection of the second groove 2213 do not overlap. In other words, the first groove 2211 and the second groove 2213 do not contact each other, so that the first groove 2211 and the second groove 2213 are not connected. The first groove 2211 and the second groove 2213 may be spaced apart in the width direction Z of the wall portion, or they may be spaced apart in the thickness direction X of the wall portion.

[0293] In this embodiment, by setting the first groove 2211 and the second groove 2213 to a structure in which the projections in the thickness direction X of the wall portion do not overlap with each other, so that the first groove 2211 and the second groove 2213 do not contact each other, on the one hand, the mutual influence between the first groove 2211 and the second groove 2213 during the processing process can be reduced; on the other hand, the phenomenon that the first weak portion 222 causes the second weak portion 223 to crack when it cracks to release pressure can be reduced, and the stress influence between the first weak portion 222 and the second weak portion 223 can be reduced.

[0294] In some embodiments, referring to Figures 9, 12, 13 and 14, the wall portion 211 is a rectangular structure, the second groove 2213 extends along the length direction Y of the wall portion, and along the width direction Z of the wall portion, the second groove 2213 is located between the first groove 2211 and the edge of the wall portion 211.

[0295] In which, along the width direction Z of the wall portion, the second groove 2213 and the first groove 2211 are spaced apart.

[0296] Exemplarily, in FIG9 , FIG13 and FIG14 , the first groove 2211 is provided with a second groove 2213 on both sides of the wall portion in the width direction Z, so that a second groove 2213 is provided between the first groove 2211 and both edges of the wall portion 211 .

[0297] 9 and 13 , in an embodiment where the first groove 2211 includes a first groove segment 2211a , a second groove segment 2211b and a third groove segment 2211c , the second groove segment 2211b extends along the length direction Y of the wall portion, and the second groove segment 2211b is arranged parallel to the second groove 2213 .

[0298] In this embodiment, by arranging the second groove 2213 between the first groove 2211 and the edge of the wall portion 211 along the width direction Z of the wall portion, the second groove 2213 can also play a certain buffering role on the first groove 2211, so that when the battery cell 20 is subjected to internal and external impact forces and deformed, the second groove 2213 can also absorb the deformation energy of the battery cell 20, so as to play a certain protective role for the area where the first groove 2211 is provided on the pressure relief component 22, and thus can effectively reduce the deformation or damage of the area where the first groove 2211 of the pressure relief component 22 when the battery cell 20 is subjected to internal and external impact forces, thereby alleviating the situation where the battery cell 20 is prematurely actuated to release pressure during use.

[0299] According to some embodiments of the present application, referring to Figures 4, 5, 6, 9, 12, 13, and 14, a third groove 224 is provided on one side of the pressure relief component 22 along the thickness direction X of the wall portion, and the bottom of the third groove 224 forms a first area 221.

[0300] Among them, the bottom of the third groove 224 forms a first area 221, that is, the position where the third groove 224 is provided on the pressure relief component 22 and the area corresponding to the bottom surface of the third groove 224 is the first area 221, that is, the pressure relief component 22 has a locally thinned area formed by the third groove 224, and the thinned area is the first area 221. Correspondingly, the thickness D1 of the first area 221 is the thickness of the area of ​​the pressure relief component 22 corresponding to the bottom surface of the third groove 224.

[0301] For example, in Figures 4, 5 and 6, the pressure relief component 22 and the wall portion 211 are separately arranged structures, and correspondingly, the third groove 224 is arranged on one side of the pressure relief component 22, so that the portion of the pressure relief component 22 corresponding to the bottom surface of the third groove 224 is the first area 221, and the third groove 224 can be arranged on the side of the pressure relief component 22 facing the interior of the shell 21, or it can be arranged on the side of the pressure relief component 22 away from the interior of the shell 21.

[0302] For example, in Figures 9, 12, 13 and 14, the pressure relief component 22 and the wall portion 211 are an integrally formed structure, that is, the pressure relief component 22 is the wall portion 211, and correspondingly, the third groove 224 is arranged on one side of the wall portion 211, so that the portion of the wall portion 211 corresponding to the bottom surface of the third groove 224 is the first area 221, and the third groove 224 can be arranged on the side of the wall portion 211 facing the interior of the shell 21, or it can be arranged on the side of the wall portion 211 away from the interior of the shell 21.

[0303] In this embodiment, a third groove 224 is provided on one side of the pressure relief component 22, and the first region 221 of the pressure relief component 22 is formed at the bottom of the third groove 224, so that the first region 221 of the pressure relief component 22 is a region where the thickness of the pressure relief component 22 is thinned, so that the structural strength of the first region 221 can be weaker than the structural strength of the non-thinned region of the pressure relief component 22, so as to further enhance the effect of the first region 221 in absorbing the stress generated by the expansion of the battery cell 20, thereby further alleviating the phenomenon that the stress is transferred to the first weak portion 222 and the stress concentration is generated in the first weak portion 222, so as to reduce the strain and strain amplitude of the first weak portion 222 of the pressure relief component 22, which is beneficial to reduce the phenomenon of premature cracking of the pressure relief component 22 during use, so as to enhance the service life of the battery cell 20.

[0304] In some embodiments, referring to Figures 4, 5, and 6 as well as Figures 9, 12, 13, and 14, the third groove 224 is disposed on a side of the pressure relief component 22 facing away from the interior of the housing 21 along the thickness direction X of the wall portion. In other words, the third groove 224 is disposed facing the electrode assembly 23 of the battery cell 20.

[0305] In this embodiment, by arranging the third groove 224 on the outer surface of the pressure relief component 22 facing away from the interior of the shell 21, it is convenient to process and form the third groove 224 on the pressure relief component 22, which is beneficial to reduce the processing difficulty of the third groove 224 and improve the production efficiency of the battery cell 20.

[0306] According to some embodiments of the present application, as shown in Figures 3, 4 and 5, the pressure relief component 22 is separately provided from the wall portion 211. That is, the pressure relief component 22 and the wall portion 211 are two separately provided components, and the pressure relief component 22 is mounted on the wall portion 211.

[0307] A pressure relief hole for installing a pressure relief component 22 is provided on the wall portion 211 . The pressure relief component 22 is connected to the hole wall of the pressure relief hole and covers the pressure relief hole. Exemplarily, the pressure relief component 22 is welded to the wall portion 211 .

[0308] In this embodiment, the pressure relief component 22 and the wall portion 211 are arranged as separate structures, so that the pressure relief component 22 is a structure installed on the wall portion 211. The battery cell 20 adopting this structure can reduce the difficulty of setting the pressure relief component 22 on the wall portion 211, and the processing steps of the outer shell 21 and the processing steps of the pressure relief component 22 can be carried out simultaneously, which is conducive to optimizing the production rhythm of the battery cell 20.

[0309] According to some embodiments of the present application, as shown in Figures 8 and 9 , the pressure relief component 22 is integrally formed with the wall portion 211. In other words, the pressure relief component 22 and the wall portion 211 are an integral structure, and the first region 221 and the first weakened portion 222 of the pressure relief component 22 are provided on the wall portion 211 using an integral molding process. That is, the pressure relief component 22 is the wall portion 211, making the pressure relief component 22 a part of the housing 21.

[0310] For example, in FIG8 , the wall portion 211 is the bottom wall of the housing 212, which is disposed opposite the end cap 213 in the wall thickness direction X. The pressure relief component 22 is then the bottom wall, and the third groove 224 forming the first region 221 and the first groove 2211 forming the first weakened portion 222 are disposed on the bottom wall. If the wall portion 211 is the end cap 213, the pressure relief component 22 is also the end cap 213, enabling the pressure relief component 22 to seal the opening 2121 of the housing 212, and both electrode terminals 24 are mounted on the pressure relief component 22.

[0311] In some embodiments, along the thickness direction X of the wall portion, the thickness of the wall portion 211 is greater than or equal to 0.8 mm and less than or equal to 2.5 mm.

[0312] Along the thickness direction X of the wall, the thickness of the wall can be any one of 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, 1.45mm, 1.5mm, 1.55mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm, 1.8mm, 1.85mm, 1.9mm, 1.95mm, 2mm, 2.05mm, 2.1mm, 2.15mm, 2.2mm, 2.25mm, 2.3mm, 2.35mm, 2.4mm, 2.45mm, 2.5mm, etc., or a range of values ​​between any two of them.

[0313] In this embodiment, the pressure relief component 22 and the wall portion 211 are arranged as an integrally formed structure, so that the pressure relief component 22 is a structure integrated on the wall portion 211, that is, the pressure relief component 22 is a wall of the outer shell 21, and correspondingly, the wall portion 211 is provided with structures such as the first area 221 and the first weak portion 222. The battery cell 20 adopting such a structure can improve the structural strength of the pressure relief component 22 arranged on the wall portion 211, and can reduce the risk of leakage caused by improper assembly between the pressure relief component 22 and the wall portion 211.

[0314] According to some embodiments of the present application, the wall portion 211 is made of steel.

[0315] Exemplarily, the material of the wall portion 211 may be carbon steel, alloy steel, stainless steel, or the like.

[0316] It should be noted that the material of the wall portion 211 includes steel. If the wall portion 211 is the end cover 213 of the outer shell 21, the material of the end cover 213 is steel; if the wall portion 211 is a wall in the shell 212, the material of the shell 212 is steel.

[0317] In this embodiment, by setting the material of the wall portion 211 to steel, due to the high strength of steel, the wall portion 211 made of steel has better strength, so that when the bursting pressure of the battery cell 20 is constant, the wall portion 211 can be made thinner, which is beneficial to saving the space occupied by the wall portion 211.

[0318] In some embodiments, the steel material is carbon steel or stainless steel.

[0319] Illustratively, the carbon steel may be low carbon steel, medium carbon steel, or high carbon steel.

[0320] In this embodiment, carbon steel or stainless steel is used as the material of the wall portion 211 , which is low in cost and easy to manufacture.

[0321] According to some embodiments of the present application, the material of the wall portion 211 includes aluminum alloy.

[0322] It should be noted that the material of the wall portion 211 includes aluminum alloy. If the wall portion 211 is the end cover 213 of the outer shell 21, the material of the end cover 213 is aluminum alloy; if the wall portion 211 is a wall in the shell 212, the material of the shell 212 is aluminum alloy.

[0323] In this embodiment, by setting the material of the wall portion 211 to aluminum alloy, it is easier to process the first groove 2211 on the wall portion 211 due to the characteristics of aluminum alloy being light weight and good ductility, which helps to reduce the manufacturing difficulty of the first groove 2211.

[0324] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other individual elements ≤ 0.03%.

[0325] In this embodiment, the aluminum alloy belongs to the third series aluminum. The aluminum alloy has lower hardness and better forming ability, which can further reduce the processing difficulty of the first groove 2211 and improve the processing accuracy of the first groove 2211, thereby helping to improve the pressure relief consistency of the battery cell 20.

[0326] In some embodiments, the aluminum alloy includes the following components in percentage by mass: aluminum ≥ 96.7%, 0.05% ≤ copper ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other single element components ≤ 0.05%, and the total composition of other elements ≤ 0.15%.

[0327] In this embodiment, the aluminum alloy belongs to series V aluminum. The wall portion 211 made of the aluminum alloy has higher hardness and greater strength, so that the wall portion 211 has good anti-destruction ability.

[0328] According to some embodiments of the present application, as shown in Figures 3 and 4, the outer shell 21 may include a shell 212 and an end cover 213, the interior of the shell 212 forms a accommodating cavity with an opening 2121, the accommodating cavity is used to accommodate the electrode assembly 23, the end cover 213 closes the opening 2121, and the end cover 213 is a wall portion 211.

[0329] The end cover 213 is the wall portion 211 , that is, the pressure relief component 22 is disposed on the end cover 213 .

[0330] In this embodiment, by setting the wall portion 211 of the shell 21 as the end cover 213 of the shell 21 for closing the opening 2121, the battery cell 20 adopting this structure is convenient for setting the pressure relief component 22 on the end cover 213, which is beneficial to reducing the manufacturing difficulty of the battery cell 20 and improving the production efficiency of the battery cell 20.

[0331] It should be noted that the structure of the battery cell 20 is not limited to this. In some embodiments, the battery cell 20 may also have other structures. For example, as shown in Figures 8 and 9, the outer shell 21 may include a shell 212 and an end cover 213. The interior of the shell 212 forms a accommodating cavity with an opening 2121, which is used to accommodate the electrode assembly 23. The end cover 213 closes the opening 2121, and the shell 212 includes a wall portion 211.

[0332] The shell 212 includes an integrally formed side wall and bottom wall, that is, the shell 212 is manufactured using an integral molding process, such as an integral molding process such as stamping, casting or extrusion molding. In other words, the side wall and bottom wall of the shell 212 are an integral structure.

[0333] The housing 212 includes a wall portion 211. That is, the wall portion 211 is a wall of the housing 212. For example, in FIG8 , the wall portion 211 is a bottom wall of the housing 212 disposed opposite the end cap 213 in the thickness direction X of the wall portion. Of course, in other embodiments, the wall portion 211 may also be a side wall of the housing 212.

[0334] In this embodiment, by setting the wall portion 211 of the outer shell 21 as a wall of the shell 212, the battery cell 20 adopting this structure can make the area of ​​the outer shell 21 where the pressure relief component 22 is provided away from the end cover 213, thereby effectively alleviating the stress generated by the connection between the end cover 213 and the shell 212 acting on the pressure relief component 22, thereby reducing the impact on the first area 221 and the first weak portion 222 of the pressure relief component 22, and further helping to reduce the risk of cracking or structural strength reduction of the pressure relief component 22 under the pulling action of stress, thereby improving the service life and reliability of the battery cell 20.

[0335] It should be noted that the battery cell 20 can have various structures. In some embodiments, the housing 21 includes a shell 212 and two end caps 213. The shell 212 has a housing cavity formed therein for accommodating the electrode assembly 23. The shell 212 has openings 2121 formed at opposite ends thereof, and both openings 2121 communicate with the housing cavity. The two end caps 213 respectively seal the two openings 2121, and one of the end caps 213 is a wall portion 211.

[0336] In this embodiment, the shell 212 of the outer shell 21 is provided with openings 2121 at both opposite ends, and the two end covers 213 respectively close the two openings 2121, and the wall portion 211 is one of the two end covers 213. The battery cell 20 adopting this structure is convenient for assembling the battery cell 20 from both ends of the shell 212, which is beneficial to reducing the manufacturing difficulty and assembly difficulty of the battery cell 20, and is convenient for setting the pressure relief component 22 on the end cover 213, which is beneficial to reducing the manufacturing difficulty of the battery cell 20 and improving the production efficiency of the battery cell 20.

[0337] Of course, the structure of the battery cell 20 is not limited to this. In the embodiment where the outer shell 21 may include a shell 212 and two end caps 213, the shell 212 may also include a wall portion 211, that is, the wall portion 211 is a wall of the shell 212. By setting the wall portion 211 of the outer shell 21 as a wall of the shell 212, the battery cell 20 adopting this structure can make the area of ​​the outer shell 21 where the pressure relief component 22 is provided away from the end caps 213, thereby effectively alleviating the stress generated by the connection between the end caps 213 and the shell 212 acting on the pressure relief component 22, thereby reducing the impact on the first area 221 and the first weak portion 222 of the pressure relief component 22, and thus helping to reduce the risk of cracking or structural strength reduction of the pressure relief component 22 under the pulling effect of stress, thereby improving the service life and reliability of the battery cell 20.

[0338] According to some embodiments of the present application, the present application further provides a battery 100 , which includes the battery cell 20 of any of the above solutions.

[0339] As shown in FIG. 2 , the battery 100 may further include a box body 10 , in which the battery cells 20 are accommodated.

[0340] In some embodiments, the box body 10 may include a first box body 11 and a second box body 12 . The first box body 11 and the second box body 12 cover each other, and the first box body 11 and the second box body 12 jointly define an assembly space for accommodating the battery cells 20 .

[0341] Optionally, the second box body 12 can be a hollow structure with one end open, and the first box body 11 can be a plate-like structure, and the first box body 11 covers the open side of the second box body 12, so that the first box body 11 and the second box body 12 jointly define an assembly space; the first box body 11 and the second box body 12 can also be hollow structures with one side open, and the open side of the first box body 11 covers the open side of the second box body 12.

[0342] Of course, the box body 10 formed by the first box body 11 and the second box body 12 can be in various shapes, such as a cylinder or a rectangular parallelepiped, etc. For example, in FIG2 , the box body 10 is a rectangular parallelepiped structure.

[0343] Optionally, the number of battery cells 20 disposed within the housing 10 may be one or more. For example, in FIG2 , the housing 10 of the battery 100 includes multiple battery cells 20, which may be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a configuration in which multiple battery cells 20 are connected in both series and parallel. Multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure formed by the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery 100 may comprise multiple battery cells 20 that are first connected in series, in parallel, or in a hybrid configuration to form a battery module, which is then further connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed within the housing 10.

[0344] The battery 100 may further include other structures. For example, the battery 100 may further include a busbar component that connects the plurality of battery cells 20 to achieve electrical connection between the plurality of battery cells 20 .

[0345] It should be noted that in some embodiments, the battery 100 may not be provided with a housing 10. The battery 100 includes multiple battery cells 20, and the battery 100 composed of multiple battery cells 20 can be directly assembled on an electrical device to provide electrical energy to the electrical device through the multiple battery cells 20. In other words, the housing 10 can serve as part of the electrical device. Taking the vehicle 1000 as an example, the housing 10 can serve as part of the chassis structure of the vehicle 1000. For example, a portion of the housing 10 can form at least a portion of the floor of the vehicle 1000, or a portion of the housing 10 can form at least a portion of the crossbeam and longitudinal beam of the vehicle 1000.

[0346] According to some embodiments of the present application, the present application further provides an electrical device, which includes the battery cell 20 of any of the above solutions, and the battery cell 20 is used to provide electrical energy to the electrical device.

[0347] The electrical device may be any of the aforementioned devices or systems using the battery cell 20 .

[0348] According to some embodiments of the present application, as shown in Figures 3 to 7, the present application provides a battery cell 20, which includes a housing 21, an electrode assembly 23, and a pressure relief component 22. The housing 21 has a wall portion 211, and includes a shell 212 and an end cap 213. The interior of the shell 212 forms a receiving cavity with an opening 2121, and the electrode assembly 23 is received in the receiving cavity. The end cap 213 closes the opening 2121, and the end cap 213 serves as the wall portion 211. The pressure relief component 22 and the wall portion 211 are separately arranged structures. The pressure relief component 22 is arranged on the wall portion 211. A third groove 224 is provided on the side of the pressure relief component 22 facing away from the interior of the shell 21. The bottom of the third groove 224 forms a first area 221. The first area 221 is provided with a first groove 2211. The first groove 2211 is arranged on the side of the first area 221 facing away from the interior of the shell 21, and the first groove 2211 is an annular structure. The first groove 2211 includes multiple grooves arranged in sequence along the thickness direction X of the wall portion. A first weak portion 222 is formed at the bottom of the first groove 2211. The pressure relief component 22 is configured to be able to crack along at least part of the first weak portion 222 when the battery cell 20 is depressurized to release the internal pressure of the battery cell 20.

[0349] The first weak portion 222 includes a weak section 2221, the cross-sectional area of ​​the weak section 2221 perpendicular to its extension direction is S, and the thickness of the first region 221 along the thickness direction X of the wall portion is D1, which satisfies 0.005≤S / D1≤1.2, preferably 0.008≤S / D1≤0.8, 0.2mm≤D1≤0.8mm, 0.008mm 2 ≤S≤0.12mm 2 The maximum width of the bottom surface of the first groove 2211 is W. Along the thickness direction X of the wall portion, the minimum residual thickness of the first groove 2211 is D2, S=W×D2, satisfying 0.1mm≤W≤0.3mm, 0.08mm≤D2≤0.4mm, preferably, 0.16mm≤W≤0.24mm, 0.12mm≤D2≤0.3mm.

[0350] According to some embodiments of the present application, as shown in Figures 8 to 11, the present application provides a battery cell 20, which includes a housing 21, an electrode assembly 23, and a pressure relief component 22. The housing 21 has a wall portion 211, and the housing 21 includes a shell 212 and an end cap 213. The interior of the shell 212 forms a receiving cavity with an opening 2121, and the electrode assembly 23 is received in the receiving cavity. The end cap 213 closes the opening 2121. The bottom wall of the housing 212, which is arranged opposite the end cap 213 in the thickness direction X of the wall portion, is the wall portion 211. The pressure relief component 22 and the wall portion 211 are an integrally formed structure, that is, the pressure relief component 22 is the wall portion 211 of the shell 21, and a third groove 224 is provided on the side of the pressure relief component 22 facing away from the interior of the shell 21. The bottom of the third groove 224 forms a first area 221, and the first area 221 is provided with a first groove 2211 and a second groove 2213. The first groove 2211 is provided on the side of the first area 221 facing away from the interior of the shell 21. The first groove 2211 includes a multi-stage groove arranged in sequence along the thickness direction X of the wall portion. A first weak portion 222 is formed at the bottom of the first groove 2211, and the first weak portion 222 includes at least one weak section 2221. The first groove 2211 includes a first groove section 2211a, a second groove section 2211b, a third groove section 2211c and a fourth groove section 2211d. The bottoms of the first groove section 2211a, the second groove section 2211b, the third groove section 2211c and the fourth groove section 2211d are all formed into a weak section 2221. The first groove section 2211a and the third groove section 2211c are arranged opposite to each other along the length direction Y of the wall portion and extend along the width direction Z of the wall portion. The second groove section 2211b connects the first groove section 2211a and the third groove section 2211c. The second groove section 2211b extends along the length direction Y of the wall portion. The first groove section 2211a, the second groove section 2211b, and the third groove section 2211c collectively define a predetermined pressure relief area 2212. The predetermined pressure relief area 2212 is configured to be opened when the pressure relief component 22 is ruptured along at least a portion of the first weak portion 222, thereby relieving the internal pressure of the battery cell 20. The connection position between the first groove section 2211a and the second groove section 2211b is offset from the ends of the first groove section 2211a, and the connection position between the third groove section 2211c and the second groove section 2211b is offset from the ends of the third groove section 2211c, so that the predetermined pressure relief area 2212 is formed on both sides of the second groove section 2211b. The first slot section 2211a, the second slot section 2211b, and the third slot section 2211c all extend along straight lines, and the first slot section 2211a and the third slot section 2211c are perpendicular to the second slot section 2211b. The fourth slot section 2211d is located between the first slot section 2211a and the third slot section 2211c, and is connected to the second slot section 2211b.The bottom of the second groove 2213 forms a second weak portion 223. Along the wall's thickness direction X, the second weak portion 223 is thicker than the first weak portion 222. The second weak portion 223 is configured to guide the predetermined pressure relief area 2212 to flip when the first weak portion 222 ruptures, thereby releasing the internal pressure of the battery cell 20. Along the wall's thickness direction X, the first groove 2211 and the second groove 2213 are respectively provided on either side of the first region 221. The second groove 2213 is provided on the side of the first region 221 facing the interior of the housing 21.

[0351] The cross-sectional area of ​​the weak section 2221 perpendicular to its extension direction is S, and the thickness of the first region 221 along the thickness direction X of the wall is D1, which satisfies the following conditions: 0.005≤S / D1≤1.2, preferably, 0.008≤S / D1≤0.8, 0.2mm≤D1≤0.8mm, 0.008mm 2 ≤S≤0.12mm 2 The maximum width of the bottom surface of the first groove 2211 is W. Along the thickness direction X of the wall portion, the minimum residual thickness of the first groove 2211 is D2, S=W×D2, satisfying 0.1mm≤W≤0.3mm, 0.08mm≤D2≤0.4mm, preferably, 0.16mm≤W≤0.24mm, 0.12mm≤D2≤0.3mm.

[0352] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0353] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, comprising: a housing having a wall portion; and a pressure relief member disposed on the wall portion, the pressure relief member having a first region in which a first weak portion is formed, the pressure relief member being configured to crack along at least a part of the first weak portion when the battery cell is depressurized to release the internal pressure of the battery cell; Among them, the first weak part includes at least one weak segment, the cross-sectional area of the weak segment perpendicular to its extension direction is S, and along the thickness direction of the wall part, the thickness of the first area is D1, satisfying 0.008 mm 2 ≤ S ≤ 0.12 mm 2 , 0.2 mm ≤ D1 ≤ 0.8 mm.

2. The battery cell according to claim 1, wherein a first groove is provided on the first region, and at least one of the weak segments is formed at the bottom of the first groove.

3. The battery cell according to claim 2, wherein, The maximum width of the weak segment is W, and along the thickness direction of the wall portion, the minimum thickness of the weak segment is D2. The product of the maximum width W of the weak segment and the minimum thickness D2 of the weak segment is the area S of the cross-section of the weak segment perpendicular to its extending direction, satisfying 0.1 mm ≤ W ≤ 0.3 mm and 0.08 mm ≤ D2 ≤ 0.4 mm.

4. The battery cell according to claim 3, wherein, 0.16 mm ≤ W ≤ 0.24 mm.

5. The battery cell according to claim 3 or 4, wherein 0.12 mm ≤ D2 ≤ 0.3 mm.

6. The battery cell according to any one of claims 2-5, wherein, Along the thickness direction of the wall portion, the first groove is provided on a side of the first region facing away from the interior of the housing.

7. The battery cell according to any one of claims 2-6, wherein The first groove includes multiple stages of grooves arranged in sequence along the thickness direction of the wall portion.

8. The battery cell according to any one of claims 2-7, wherein, The first groove is an annular groove connected end to end, and the bottom of the first groove forms the weak segment in an annular structure.

9. The battery cell according to any one of claims 2-7, wherein, The first groove includes a first groove segment and a second groove segment. The bottoms of the first groove segment and the second groove segment both form the weak segment. The first groove segment is connected to the second groove segment. The first groove segment and the second groove segment jointly define a predetermined pressure relief area, and the predetermined pressure relief area is configured to be opened when the pressure relief member cracks along at least a part of the first weak portion to release the internal pressure of the battery cell.

10. The battery cell according to any one of claims 2-7, wherein, The first groove includes a first groove segment, a second groove segment, and a third groove segment. The bottoms of the first groove segment, the second groove segment, and the third groove segment all form the weak segment. The first groove segment and the third groove segment are oppositely arranged. The second groove segment connects the first groove segment and the third groove segment. The first groove segment, the second groove segment, and the third groove segment jointly define a predetermined pressure relief area, and the predetermined pressure relief area is configured to be opened when the pressure relief member cracks along at least a part of the first weak portion to release the internal pressure of the battery cell.

11. The battery cell according to claim 10, wherein, The connection position of the first groove segment and the second groove segment deviates from both ends of the first groove segment, and the connection position of the third groove segment and the second groove segment deviates from both ends of the third groove segment, so that the predetermined pressure relief areas are formed on both sides of the second groove segment.

12. The battery cell according to claim 11, wherein, The first groove segment, the second groove segment, and the third groove segment all extend along a straight track, and both the first groove segment and the third groove segment are perpendicular to the second groove segment.

13. The battery cell according to claim 10, wherein, The first groove segment, the second groove segment, and the third groove segment all extend along an arc track.

14. The battery cell according to any one of claims 10-13, wherein, The first groove further includes a fourth groove segment, the bottom of the fourth groove segment forms the weak segment, the fourth groove segment is located between the first groove segment and the third groove segment, and the fourth groove segment is connected to the second groove segment.

15. The battery cell according to any one of claims 9-14, wherein, The first region is further formed with a second weak portion. Along the thickness direction of the wall portion, the thickness of the second weak portion is greater than that of the first weak portion. The second weak portion is configured to guide the predetermined pressure relief area to turn over when the first weak portion cracks, so as to release the internal pressure of the battery cell.

16. The battery cell according to claim 15, wherein, The first region is provided with a second groove, and the bottom of the second groove forms the second weak portion.

17. The battery cell according to claim 16, wherein, Along the thickness direction of the wall portion, the second groove is disposed on a side of the first region facing the interior of the housing.

18. The battery cell according to claim 16 or 17, wherein, Along the thickness direction of the wall portion, the first groove and the second groove are respectively disposed on two sides of the first region.

19. The battery cell according to any one of claims 16 - 18, wherein, Along the thickness direction of the wall portion, the projection of the first groove does not overlap with the projection of the second groove.

20. The battery cell according to claim 19, wherein, The wall portion is of a rectangular structure, the second groove extends along the length direction of the wall portion, and along the width direction of the wall portion, the second groove is located between the first groove and the edge of the wall portion.

21. The battery cell according to any one of claims 1-20, wherein, Along the thickness direction of the wall portion, a third groove is provided on one side of the pressure relief component, and the bottom of the third groove forms the first region.

22. The battery cell according to claim 21, wherein, Along the thickness direction of the wall portion, the third groove is disposed on a side of the pressure relief component facing away from the interior of the housing.

23. The battery cell according to any one of claims 1-22, wherein, The pressure relief component is separately provided from the wall portion.

24. The battery cell according to any one of claims 1-22, wherein, The pressure relief component and the wall portion are integrally formed.

25. The battery cell according to any one of claims 1-24, wherein, The housing includes: a housing body, which internally forms a receiving cavity with an opening, and the receiving cavity is used for receiving the electrode assembly; an end cover, which closes the opening; wherein, the end cover is the wall portion; or the housing body includes the wall portion.

26. The battery cell according to any one of claims 1-24, wherein, The housing includes: a housing body, which internally forms a receiving cavity for receiving the electrode assembly, openings are formed at both opposite ends of the housing body, and both of the openings communicate with the receiving cavity; two end covers, which respectively close the two openings; wherein, one of the two end covers is the wall portion; or the housing body includes the wall portion.

27. A battery, comprising the battery cell according to any one of claims 1-26.

28. An electrical device, comprising the battery cell according to any one of claims 1-26, and the battery cell is used for providing electrical energy.

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