Battery cell, battery and electric device

Abstract

The present application relates to the technical field of batteries. Provided are a battery cell, a battery and an electric device. The battery cell comprises: a casing and a pressure relief component, wherein the casing comprises a first wall portion; and the pressure relief component is arranged on the first wall portion, a first weak portion of the pressure relief component defines at least one predetermined pressure relief region, and 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. In the direction of width of the first wall portion, the dimension of the first wall portion is W, the first weak portion comprises at least one first weak section, and the area of the cross section of the first weak section that is perpendicular to the extension direction thereof is S1, wherein 10 mm≤W≤100 mm, and 0.006 mm2≤S1≤0.15 mm2. Thus, the present application can reduce the risk of the problem of electrolyte leakage caused by the situation in which the pressure relief component is activated in advance or undergoes fatigue cracking, etc., when the battery cell has been used for a long time, and same can also reduce the risks of bursting, explosion, etc., of the casing of the battery cell caused by the pressure relief component not performing pressure relief in a timely manner, thereby improving the use reliability of the battery cell.

Description

Battery cells, batteries and electrical equipment 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] Batteries are widely used in new energy vehicles, electronic equipment and other fields. As the demand for batteries increases, higher requirements are placed on battery reliability.

[0003] In battery technology, the pressure relief components of battery cells are a key factor affecting their reliability. These components are used to release pressure within the battery cells when the pressure or temperature inside the cells reaches a threshold. However, after repeated cycles and long-term use, these components are prone to premature activation or fatigue cracking, reducing the 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 to improve the reliability of the battery cell.

[0006] In a first aspect, an embodiment of the present application provides a battery cell, comprising a shell and a pressure relief component; the shell comprising a first wall portion; the pressure relief component being arranged on the first wall portion, the pressure relief component comprising a first weak portion, the first weak portion defining at least one predetermined pressure relief area, the pressure relief component being configured to be able to split along at least a portion of the first weak portion when the battery cell is pressure-relieved; wherein, along the width direction of the first wall portion, the dimension of the first wall portion is W, the first weak portion comprises at least one first weak segment, the area of ​​the cross section of the first weak segment perpendicular to its extension direction is S1, satisfying: satisfying: 10mm≤W≤100mm, 0.006mm 2 ≤S1≤0.15mm 2 .

[0007] In the above technical solution, the first wall portion of the housing is provided with a pressure relief component, which includes a first weak portion. The first weak portion is capable of rupturing when the battery cell releases pressure to release the pressure inside the battery cell, thereby reducing the risk of explosion, fire, and other problems caused by excessive internal pressure in the battery cell. The first wall portion has a width dimension of 10 mm to 100 mm. Setting the width dimension of the first wall portion to be greater than or equal to 10 mm alleviates the phenomenon that the pressure relief component requires an excessively high burst pressure when releasing pressure from the battery cell due to the excessive pressure bearing capacity of the first weak section of the first weak portion. This further reduces the risk of the battery cell housing bursting, exploding, or catching fire due to untimely pressure relief from the pressure relief component, thereby effectively improving the reliability of the battery cell. Setting the dimension of the first wall portion along its width direction to be less than or equal to 100mm can reduce the deformation of the first weak section when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component, thereby reducing the phenomenon of reduced structural strength of the first weak section of the pressure relief component due to excessive deformation, and further reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component at the first weak section after long-term use of the battery cell, thereby further improving the stability of the pressure relief component and further improving the service life and reliability of the battery cell. The area of ​​the cross section of the first weak section perpendicular to its extension direction is 0.006mm 2 to 0.15mm 2 , set the cross-sectional area of ​​the first weak section perpendicular to its extension direction to be greater than or equal to 0.006mm 2 , which can reduce the deformation of the first weak section when the expansion force generated by the expansion of the battery cell acts on the pressure relief component during use, thereby reducing the phenomenon of reduced structural strength of the first weak section of the pressure relief component due to excessive deformation, further reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component at the first weak section after long-term use of the battery cell, thereby further improving the stability of the pressure relief component and further improving the service life and reliability of the battery cell. The area of ​​the cross section of the first weak section perpendicular to its extension direction is set to be less than or equal to 0.15mm 2 , which can alleviate the phenomenon that the pressure-bearing capacity of the first weak section of the first weak part is too large, resulting in the pressure relief component requiring too large a bursting pressure when releasing pressure from the battery cell. This can further reduce the risk of bursting, explosion, fire, etc. of the battery cell shell caused by untimely pressure relief of the pressure relief component, and thus can effectively improve the reliability of the battery cell.

[0008] In some embodiments of the first aspect of the present application, 20 mm ≤ W ≤ 80 mm, 0.01 mm 2 ≤S1≤0.1mm 2 .

[0009] In the above technical solution, the width of the first wall portion is further limited to 20 mm to 80 mm. Setting the width of the first wall portion to be greater than or equal to 20 mm further mitigates the problem of excessive pressure bearing capacity of the first weak section of the first weak portion, which may result in excessive burst pressure required by the pressure relief component when releasing pressure from the battery cell. This further reduces the risk of battery cell casing rupture, explosion, or fire caused by untimely pressure relief from the pressure relief component, thereby effectively improving the reliability of the battery cell. Setting the width of the first wall portion to be less than or equal to 80 mm further reduces deformation of the first weak section when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component, thereby reducing the structural strength reduction of the first weak section of the pressure relief component due to excessive deformation. This further reduces the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component in the first weak section after long-term use, thereby further improving the operational stability of the pressure relief component and further enhancing the service life and reliability of the battery cell. It is further defined that the cross-sectional area of ​​the first weak section perpendicular to its extension direction is 0.01 mm 2 to 0.1mm 2 , set the cross-sectional area of ​​the first weak section perpendicular to its extension direction to be greater than or equal to 0.01mm 2 , which can further reduce the deformation of the first weak section when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component, thereby reducing the phenomenon of reduced structural strength of the first weak section of the pressure relief component due to excessive deformation, and further reduce the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component at the first weak section after long-term use of the battery cell, thereby further improving the stability of the pressure relief component and further improving the service life and reliability of the battery cell. The area of ​​the cross section of the first weak section perpendicular to its extension direction is set to be less than or equal to 0.1mm 2 , which can alleviate the phenomenon that the pressure-bearing capacity of the first weak section of the first weak part is too large, resulting in the pressure relief component requiring too large a bursting pressure when releasing pressure from the battery cell. This can further reduce the risk of bursting, explosion, fire, etc. of the battery cell shell caused by untimely pressure relief of the pressure relief component, and thus can effectively improve the reliability of the battery cell.

[0010] In some embodiments of the first aspect of the present application, the pressure relief component is provided with a first groove, the first groove includes at least one groove segment, and the pressure relief component forms at least one first weak segment in the area where the groove segment is provided, the width of the groove bottom surface of the groove segment is A, the unit is mm, the thickness of the first weak segment is H, the unit is mm, satisfying: S1=A×H; 0.1mm≤A≤0.3mm, 0.06mm≤H≤0.5mm.

[0011] In the above technical solution, the area S1 of the cross section of the first weak section of the first weak part perpendicular to its extension direction is the product of the width A of the groove bottom surface of the groove section and the thickness H of the first weak part. The width A of the groove bottom surface of the groove section is set to 0.1mm to 0.3mm, and the thickness H of the first weak part is set to 0.06mm to 0.5mm. By setting the width A of the groove bottom surface of the groove section to be greater than or equal to 0.1mm and the thickness H of the first weak part to be greater than or equal to 0.06mm, the concentration of stress generated by the expansion of the battery cell in the first weak section of the first weak part can be reduced, and the stress absorption effect of the predetermined pressure relief area can be improved, thereby further reducing the strain and strain amplitude of the first weak part of the pressure relief component, and further reducing the risk of premature actuation or fatigue cracking of the pressure relief component during use of the battery cell. By setting the width A of the bottom surface of the groove section to less than or equal to 0.3 mm and the thickness H of the first weak portion to less than or equal to 0.5 mm, the bursting pressure required by the pressure relief component during pressure relief can be reduced, thereby further reducing the risk of bursting, explosion, fire, etc. in the battery cell shell due to untimely pressure relief by the pressure relief component.

[0012] In some embodiments of the first aspect of the present application, 0.15 mm ≤ A ≤ 0.25 mm; 0.1 mm ≤ H ≤ 0.3 mm.

[0013] In the above technical solution, by setting the width A of the bottom surface of the groove section to be greater than or equal to 0.15 mm and the thickness H of the first weak portion to be greater than or equal to 0.1 mm, the concentration of stress generated by the battery cell expansion in the first weak section of the first weak portion can be further reduced, and the stress absorption effect of the predetermined pressure relief area can be further improved, thereby further reducing the strain and strain amplitude of the first weak portion of the pressure relief component, and further reducing the risk of premature activation or fatigue cracking of the pressure relief component during use of the battery cell. By setting the width A of the bottom surface of the groove section to be less than or equal to 0.25 mm and the thickness H of the first weak portion to be less than or equal to 0.3 mm, the burst pressure required by the pressure relief component during pressure relief can be further reduced, thereby further reducing the risk of bursting, explosion, fire, etc. in the battery cell casing due to untimely pressure relief from the pressure relief component.

[0014] In some embodiments of the first aspect of the present application, the pressure relief component has a first surface and a second surface arranged opposite to each other in the thickness direction of the first wall portion, and the first groove is a multi-level notched groove, and the multi-level notched groove is arranged in sequence from the first surface to the second surface. In two adjacent levels of the notched grooves, the first-level notched groove away from the first surface is arranged at the bottom surface of the first-level notched groove close to the first surface.

[0015] In the above technical solution, the first groove is set as a stepped groove structure arranged along the thickness direction of the first wall portion, so that the first groove is a groove formed by multiple processing. When this structure is used to form a first weak portion of the same thickness, on the one hand, the depth of the single processing of the notched groove can be reduced, which is beneficial to reducing the manufacturing difficulty and demand for manufacturing equipment for forming the first weak portion of the same thickness, so as to reduce manufacturing costs, and can reduce the forming force that the pressure relief component is subjected to during a single processing during the formation of the first weak portion, which is beneficial to reducing the risk of cracks in the pressure relief component, so as to improve the production quality of the battery cell. On the other hand, it can improve the flow morphology of the first weak portion during the formation process, which is beneficial to the flow of the material generated when forming the first weak portion, so as to improve the structural consistency of the multi-stage notched groove.

[0016] In some embodiments of the first aspect of the present application, the first groove includes three levels of scoring grooves, and the three levels of scoring grooves are arranged in sequence from the first surface to the second surface.

[0017] In the above technical solution, the first groove includes a three-level scoring groove. When forming a first weak portion of the same thickness, it can reduce the depth of the scoring groove in a single processing, which is beneficial to reducing the manufacturing difficulty and demand for manufacturing equipment for forming a first weak portion of the same thickness, so as to reduce manufacturing costs, and can reduce the forming force that the pressure relief component is subjected to in a single processing during the formation of the first weak portion, which is beneficial to reducing the risk of cracks in the pressure relief component, so as to improve the production quality of the battery cell. On the other hand, it can improve the flow shape of the first weak portion during the formation process, which is beneficial to the flow of the material generated when the first weak portion is formed, so as to improve the structural consistency of the multi-level scoring groove; it also alleviates the problem of increased processing time due to multiple processing required to form the first weak portion.

[0018] In some embodiments of the first aspect of the present application, the pressure relief component further includes a second weak portion, and the second weak portion is configured to guide the predetermined pressure relief area to open.

[0019] In the above technical solution, the second weak portion can guide the predetermined pressure relief area to open, 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, connection failure, etc. caused by untimely pressure relief of the battery cell, which is beneficial to improving the reliability of the battery cell.

[0020] In some embodiments of the first aspect of the present application, the pressure relief component is provided with a second groove, and the pressure relief component forms the second weak portion in a region where the second groove is provided.

[0021] In the above technical solution, the pressure relief component is provided with a second groove, so that the pressure relief component forms a second weak portion in the area corresponding to the second groove. The battery cell adopting this structure facilitates the formation of the second weak portion on the pressure relief component, which is beneficial to reducing the difficulty of forming the second weak portion on the pressure relief component, thereby improving the production efficiency of the battery cell.

[0022] In some embodiments of the first aspect of the present application, the second groove is provided on a surface of the pressure relief component facing the interior of the housing.

[0023] In the above technical solution, by arranging the second groove on the surface of the pressure relief component facing the interior of the shell, the predetermined pressure relief area 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 area during the flipping process, which is beneficial to improving the flipping effect of the predetermined pressure relief area.

[0024] In some embodiments of the first aspect of the present application, the pressure relief component has a first surface and a second surface arranged opposite to each other in the thickness direction of the first wall portion, the first surface is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided, and the second surface is provided with a second groove, and the pressure relief component forms the second weak portion in the area where the second groove is provided.

[0025] In the above technical solution, by respectively arranging the first groove and the second groove on the first surface and the second surface opposite to each other along the thickness direction of the first wall portion of the pressure relief component, it is convenient to process the first groove and the second groove on both sides of the pressure relief component along the thickness direction of the first wall portion, which is beneficial to reduce the mutual influence of the first groove and the second groove during the processing.

[0026] In some embodiments of the first aspect of the present application, the first surface is a surface of the pressure relief component facing away from the interior of the housing, and the second surface is a surface of the pressure relief component facing the interior of the housing.

[0027] In the above technical solution, by arranging the first and second grooves on the first and second surfaces of the pressure relief component, which are opposite to each other along the thickness direction of the first wall portion, respectively, it is convenient to process the first and second grooves on both sides of the pressure relief component along the thickness direction of the first wall portion, thereby reducing the mutual influence between the first and second grooves during the processing. In addition, the second groove is arranged on the second surface of the pressure relief component facing the interior of the housing, so that the predetermined pressure relief area can be flipped toward the outside of the housing around the bottom wall of the second groove after being opened. This can reduce the interference caused by the groove side of the second groove on the predetermined pressure relief area during the flipping process, thereby improving the flipping effect of the predetermined pressure relief area.

[0028] In some embodiments of the first aspect of the present application, along the thickness direction of the first wall portion, a projection of the first groove does not contact a projection of the second groove.

[0029] In the above technical solution, by setting the projection of the first groove in the thickness direction of the first wall portion and the projection of the second groove in the thickness direction of the first wall portion to a non-contact structure, on the one hand, the mutual influence between 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.

[0030] In some embodiments of the first aspect of the present application, the pressure relief component is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided; the first groove includes a first groove section and a second groove section connected, and the pressure relief component forms a first weak section in the area of ​​the first groove section, and the pressure relief component forms a first weak section in the area corresponding to the second groove section.

[0031] In the above technical solution, the first groove includes a first groove section and a second groove section, and the first groove section and the second groove section are interconnected structures. 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 interconnected weaker, which is easier to crack and open the predetermined pressure relief area to release the internal pressure of the battery cell.

[0032] In some embodiments of the first aspect of the present application, the first groove includes a third groove 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, and the pressure relief component forms a first weak segment in the area corresponding to the third groove segment.

[0033] 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 is pressure-relieved, 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.

[0034] In some embodiments of the first aspect of the present application, the position where the second slot segment is connected to the first slot segment deviates from the two ends of the first slot segment, and the position where the second slot segment is connected to the third slot segment deviates from the two ends of the third slot segment.

[0035] In the above technical solution, the position where the second groove segment is connected to the first groove segment deviates from the two ends of the first groove segment, and the connection position between the first groove segment and the second groove segment is set to be located between the two ends of the first groove segment. The position where the second groove segment is connected to the third groove segment deviates from the two ends of the third groove segment, and the connection position between the third groove segment and the second groove segment is set 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 for pressure relief 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.

[0036] In some embodiments of the first aspect of the present application, the first weak portion defines two predetermined pressure relief areas, and the two predetermined pressure relief areas are respectively located on both sides of the second groove section; the pressure relief component also includes a second weak portion, and the second weak portion is configured to guide the predetermined pressure relief area to open when the first weak portion is broken, and at least one second weak portion is corresponding to each predetermined pressure relief area.

[0037] In the above technical solution, the second weak portion can guide the corresponding predetermined pressure relief area to open, and at least one second weak portion is provided corresponding to each predetermined pressure relief area, thereby improving the opening effect of each 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, connection failure, etc. caused by untimely pressure relief of the battery cell, and is beneficial to improving the reliability of the battery cell.

[0038] In some embodiments of the first aspect of the present application, a second weak portion is correspondingly provided for each predetermined pressure relief area; the pressure relief component is provided with a second groove, and the pressure relief component forms the second weak portion in the area where the second groove is provided, and the first groove is located between the two second grooves.

[0039] In the above technical solution, the first groove is located between the two second grooves, so that 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 deformation energy of the battery cell can be absorbed by the second groove, 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, so as to alleviate the situation where the battery cell is prematurely actuated to release pressure during use.

[0040] In some embodiments of the first aspect of the present application, the second slot segment and the second groove are arranged opposite to each other along a first direction, and along the first direction, the first slot segment and the third slot segment are both arranged spaced apart from the second groove.

[0041] In the above technical solution, the second groove section and the second groove are arranged opposite to each other along the first direction, and along the first direction, the first groove section and the third groove section are spaced apart from the second groove, so the first groove section, the second groove section and the third groove section are not in contact with the second groove, which can reduce the mutual influence between the first groove and the second groove during the processing process, and reduce the phenomenon that the first weak part causes the second weak part to crack when the first weak part cracks to release pressure, and can reduce the stress influence between the first weak part and the second weak part.

[0042] In some embodiments of the first aspect of the present application, the first wall portion is a rectangular structure, and the first direction is parallel to the width direction of the first wall portion.

[0043] In the above technical solution, the first direction is parallel to the width direction of the first wall portion, and the second groove section and the second groove are arranged opposite to each other along the width direction of the first wall portion. Along the width direction of the first wall portion, the first groove section and the third groove section are spaced apart from the second groove. The first groove section, the second groove section and the third groove section are not in contact with the second groove in the width direction of the first wall portion. This can reduce the mutual influence between the first groove and the second groove during the processing process, reduce the phenomenon that the first weak portion causes the second weak portion to crack when the first weak portion cracks to release pressure, and reduce the stress influence between the first weak portion and the second weak portion.

[0044] In some embodiments of the first aspect of the present application, the pressure relief component is integrally formed with the first wall portion.

[0045] In the above technical solution, the pressure relief component and the first wall portion are arranged as an integrally formed structure, so that the pressure relief component is a structure integrated on the first wall portion, that is, the pressure relief component is a wall of the shell, and correspondingly, the pressure relief component is arranged on the first wall portion. The battery cell adopting this structure can improve the structural strength of the pressure relief component arranged on the first wall portion, and can reduce the risk of leakage between the pressure relief component and the first wall portion due to improper assembly.

[0046] In some embodiments of the first aspect of the present application, the pressure relief component is separately provided from the first wall portion, the first wall portion is provided with a pressure relief hole, and the pressure relief component is installed on the wall portion and covers the pressure relief hole.

[0047] In the above technical solution, by arranging the pressure relief component and the first wall portion as a separate structure, the pressure relief component is a structure installed on the first wall portion. The battery cell adopting this structure can reduce the difficulty of setting the pressure relief component on the first 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.

[0048] In some embodiments of the first aspect of the present application, the battery cell includes an electrode assembly, the electrode assembly is accommodated in the housing, and the first wall portion supports the electrode assembly.

[0049] In the above technical solution, the first wall supports the electrode assembly, and the pressure relief component is arranged on the first wall, which can reduce the risk of the released substance acting on other electrical connection structures when the battery cell is depressurized, thereby reducing the risk of causing other reliability problems.

[0050] In some embodiments of the first aspect of the present application, the battery cell includes an electrode terminal, and the electrode terminal is provided on a wall portion of the housing other than the first wall portion.

[0051] In the above technical solution, the electrode terminals are arranged on other walls of the shell except the first wall, so the risk of the substances discharged from the battery cell when the pressure is released acts on the electrode terminals is low, which can reduce the risk of the battery cell short circuiting and causing thermal runaway of the battery cell again due to the electrical connection formed by the substances discharged from the battery cell when the pressure is released and the electrode terminals.

[0052] In some embodiments of the first aspect of the present application, the electrode terminal is disposed on a wall portion of the housing opposite to the first wall portion.

[0053] In the above technical solution, the electrode terminal is arranged on the wall portion of the shell opposite to the first wall portion, so that the distance between the electrode terminal and the pressure relief component is farther, which can further reduce the risk of the discharged substance of the battery cell acting on the electrode terminal when the battery cell is depressurized, and further reduce the risk of the battery cell short circuit caused by the formation of electrical connection between the discharged substance and the electrode terminal when the battery cell is depressurized, causing the battery cell to short-circuit again and cause thermal runaway of the battery cell.

[0054] In some embodiments of the first aspect of the present application, the housing includes a shell and an end cover, the shell has at least one opening; the end cover corresponds to the opening one by one, the end cover is connected to the shell and closes the opening; wherein, at least one of the end covers is the first wall portion, or the shell includes the first wall portion.

[0055] In the above technical solution, by configuring the first 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 first wall portion of the housing as a wall of the shell, a battery cell employing this structure can position the area of ​​the shell 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 acting on the pressure relief component, thereby reducing the impact on the predetermined pressure relief area and the first weak portion of the pressure relief component, thereby facilitating the reduction of the risk of cracking or a decrease in structural strength of the pressure relief component under the pulling effect of stress, thereby improving the service life and reliability of the battery cell.

[0056] In some embodiments of the first aspect of the present application, the shell has two openings arranged opposite to each other; the outer shell includes two end covers, each end cover is connected to the shell and closes one opening, and the shell includes the first wall portion.

[0057] In the above technical solution, the housing has two openings arranged opposite each other, and the two end caps respectively seal the two openings. This structure facilitates assembly of the battery cells from both ends of the housing, which helps reduce the difficulty of manufacturing and assembling the battery cells. The housing includes a first wall portion, and the pressure relief components are not provided on the end caps. This can reduce the risk of substances released from the battery cells during pressure relief from interacting with other battery structures, further reducing the risk of thermal runaway of the battery cells due to the formation of electrical connection between the substances released from the battery cells during pressure relief and the electrode terminals, causing a short circuit in the battery cells.

[0058] In some embodiments of the first aspect of the present application, the shell has an opening, and a wall portion of the shell arranged opposite to the opening is the first wall portion.

[0059] In the above technical solution, the wall portion of the shell that is arranged opposite to the opening is the first wall portion, which can reduce the risk of the substance released when the battery cell is depressurized acting on other structures of the battery, thereby further reducing the risk of the battery cell short circuiting due to the electrical connection formed by the substance released when the battery cell is depressurized and the electrode terminals causing thermal runaway of the battery cell again.

[0060] In some embodiments of the first aspect of the present application, the material of the pressure relief component includes steel.

[0061] In the above technical solution, the pressure relief component is made of steel. Steel has high strength, and the pressure relief component made of steel has better strength. Under the condition of a certain burst pressure of the battery cell, the pressure relief component can be made thinner, reducing the volume of the pressure relief component.

[0062] In some embodiments of the first aspect of the present application, the steel material is carbon steel or stainless steel.

[0063] In the above technical solution, the pressure relief component is made of aluminum alloy. Aluminum alloy has the characteristics of light weight and good ductility, which makes it easier to machine the first groove on the pressure relief component.

[0064] In a second aspect, an embodiment of the present application further provides a battery comprising the above-mentioned battery cell.

[0065] In a third aspect, an embodiment of the present application further provides an electrical device comprising the above-mentioned battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] 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.

[0067] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0068] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0069] FIG3 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0070] FIG4 is an exploded view of a battery cell provided in some embodiments of the present application;

[0071] FIG5 is a schematic structural diagram of a pressure relief component provided in some embodiments of the present application;

[0072] FIG6 is a cross-sectional view of a pressure relief component provided in some embodiments of the present application;

[0073] FIG7 is an enlarged view of point B1 in FIG6 ;

[0074] FIG8 is a bottom view of a housing provided in some embodiments of the present application;

[0075] FIG9 is a bottom view of a housing provided in some further embodiments of the present application;

[0076] FIG10 is a schematic structural diagram of a shell of a battery cell provided in some embodiments of the present application;

[0077] FIG11 is a bottom view of a housing provided in some other embodiments of the present application;

[0078] FIG12 is a cross-sectional view taken along the Q1-Q1 direction in FIG11 ;

[0079] FIG13 is an enlarged view of point B2 in FIG12 ;

[0080] FIG14 is a cross-sectional view taken along the line Q2-Q2 in FIG11;

[0081] FIG15 is an enlarged view of point B3 in FIG14 ;

[0082] FIG16 is an enlarged view of point B4 in FIG14 ;

[0083] FIG17 is a bottom view of a housing provided in some other embodiments of the present application;

[0084] FIG18 is a cross-sectional view taken along the line Q3-Q3 in FIG17 ;

[0085] FIG19 is an enlarged view of point B5 in FIG18 ;

[0086] FIG20 is an enlarged view of point B6 in FIG18 .

[0087] Icon: 1000-vehicle; 100-battery; 10-box; 11-first box body; 12-second box body; 20-battery cell; 21-housing; 211-first wall; 212-housing; 212a-first side wall; 212b-second side wall; 2121-opening; 213-end cover; 22-pressure relief component; 221-first weak portion; 2211-first weak section; 222-first groove; 2221-first groove section; 2222-second groove section; 2223-third groove section; 2224-fourth groove section; 223-first surface; 224-second surface; 222a-first sub-groove; 222 a1-first section; 222a2-second section; 222a3-third section; 222b-second sub-groove; 222b1-fourth section; 222b2-fifth section; 222b3-sixth section; 222c-third sub-groove; 222c1-seventh section; 222c2-eighth section; 222c3-ninth section; 225-second groove; 228-second weak part; 23-electrode assembly; 231-ear; 24-electrode terminal; 25-current collecting member; 200-controller; 300-motor; P-predetermined pressure relief area; X-thickness direction of the first wall; Y-length direction of the first wall; Z-width direction of the first wall. DETAILED DESCRIPTION

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] The term "plurality" used in this application refers to two or more (including two).

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.).

[0100] 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 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi0.5 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.

[0101] 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.

[0102] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0103] 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.).

[0104] 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.

[0105] 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.

[0106] As an example, the negative electrode active material may adopt the negative electrode active material for the battery cell 20 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.

[0107] 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.

[0108] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0116] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0117] 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.

[0118] 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.

[0119] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0120] 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.

[0121] In some embodiments, the electrode assembly is a laminate structure.

[0122] 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.

[0123] 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.

[0124] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0125] 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.

[0126] 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.

[0127] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0136] 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 reliability must be considered.

[0137] In battery technology, for typical battery cells, to reduce the risk of explosion, fire, and other issues, a pressure relief component can be installed on the battery cell to release the internal pressure of the battery cell through the pressure relief component, thereby reducing the risk of explosion, fire, and other issues in the battery cell and improving the reliability of the battery cell. In related art, the pressure relief component is typically formed on the housing using an integral molding process, that is, integrated into the battery cell housing, or connected to the wall of the housing through welding, clamping, etc., so that when the internal pressure or temperature of the battery cell reaches a threshold, the pressure relief component can be activated and opened to release the internal pressure of the battery cell. However, battery cells are prone to expansion during use or charging and discharging. The expansion force generated by the battery cell acts on the pressure relief component, causing the pressure relief component to be extremely prone to stretching and deformation, resulting in strain and large strain amplitude in the pressure relief component. This reduces the structural strength of the pressure relief component of the battery cell, resulting in poor operational stability of the pressure relief component, and is prone to premature activation or fatigue cracking during use, which is not conducive to improving the service life and reliability of the battery cell.

[0138] Based on the above considerations, in order to alleviate 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 includes a first wall portion; the pressure relief component is arranged on the first wall portion, the pressure relief component includes a first weak portion, the first weak portion defines at least one predetermined pressure relief area, and 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; wherein, along the width direction of the first wall portion, the size of the first wall portion is W, the first weak portion includes at least one first weak section, the area of ​​the cross section of the first weak section perpendicular to its extension direction is S1, satisfying: satisfying: 10mm≤W≤100mm, 0.006mm 2 ≤S1≤0.15mm 2 .

[0139] The first wall of the shell is provided with a pressure relief component, which includes a first weak portion. The first weak portion can be broken when the battery cell is depressurized to release the pressure inside the battery cell, thereby reducing the occurrence of explosion, fire and other problems caused by excessive pressure inside the battery cell.

[0140] The first wall portion has a width dimension of 10 mm to 100 mm. Setting the width dimension of the first wall portion to be greater than or equal to 10 mm mitigates the problem of excessive pressure bearing capacity of the first weak section of the first weak portion, which may result in an excessively high burst pressure required by the pressure relief component when releasing pressure from the battery cell. This further reduces the risk of bursting, explosion, or fire in the battery cell casing due to untimely pressure relief from the pressure relief component, thereby effectively improving the reliability of the battery cell. Setting the width dimension of the first wall portion to be less than or equal to 100 mm reduces deformation of the first weak section when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component. This reduces the structural strength reduction of the first weak section of the pressure relief component due to excessive deformation, further reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component in the first weak section after long-term use. This further improves the operational stability of the pressure relief component and further enhances the service life and reliability of the battery cell.

[0141] The cross-sectional area of ​​the first weak section perpendicular to its extension direction is 0.006 mm 2 to 0.15mm 2 , set the cross-sectional area of ​​the first weak section perpendicular to its extension direction to be greater than or equal to 0.006mm 2 , which can reduce the deformation of the first weak section when the expansion force generated by the expansion of the battery cell acts on the pressure relief component during use, thereby reducing the phenomenon of reduced structural strength of the first weak section of the pressure relief component due to excessive deformation, further reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component at the first weak section after long-term use of the battery cell, thereby further improving the stability of the pressure relief component and further improving the service life and reliability of the battery cell. The area of ​​the cross section of the first weak section perpendicular to its extension direction is set to be less than or equal to 0.15mm 2 , which can alleviate the phenomenon that the pressure-bearing capacity of the first weak section of the first weak part is too large, resulting in the pressure relief component requiring too large a bursting pressure when releasing pressure from the battery cell. This can further reduce the risk of bursting, explosion, fire, etc. of the battery cell shell caused by untimely pressure relief of the pressure relief component, and thus can effectively improve the reliability of the battery cell.

[0142] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical equipment 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 equipment. This can help alleviate issues such as premature activation of pressure relief components of the battery cells or fatigue cracking during use, thereby improving the reliability and service life of the battery cells.

[0143] The embodiments of the present application provide 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.

[0144] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device in an embodiment of the present application.

[0145] 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.

[0146] 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.

[0147] 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 structural 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 .

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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 .

[0152] 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.

[0153] In some embodiments, as shown in Figures 3, 4, 5, 6, and 7, an embodiment of the present application provides a battery cell 20, which includes a shell 21 and a pressure relief component 22; the shell 21 includes a first wall portion 211; the pressure relief component 22 is arranged on the first wall portion 211, and the pressure relief component 22 includes a first weak portion 221, which defines at least one predetermined pressure relief area P, and the pressure relief component 22 is configured to be able to split along at least part of the first weak portion 221 when the battery cell 20 is depressurized; wherein, along the width direction Z of the first wall portion, the size of the first wall portion 211 is W, the first weak portion 221 includes at least one first weak section 2211, and the area of ​​the cross section of the first weak section 2211 perpendicular to its extension direction is S1, satisfying: 10mm≤W≤100mm, 0.006mm 2 ≤S1≤0.15mm 2 .

[0154] 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.

[0155] 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.

[0156] The battery cell 20 may include one electrode assembly 23 or multiple electrode assemblies 23. In Figure 4, the battery cell 20 includes two electrode assemblies 23, which are stacked along the thickness of the electrode assemblies 23. The stacking direction of the two electrode assemblies 23 may be the thickness direction of the battery cell 20. Of course, in other embodiments, the number of electrode assemblies 23 included in the battery cell 20 may also be three, four, five, etc.

[0157] In some embodiments, the battery cell 20 further includes an electrolyte contained in the housing 21. The electrolyte may be an electrolytic solution.

[0158] 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 at least one opening 2121. That is, the shell 212 is a hollow structure with at least one end opening 2121, 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.

[0159] The first wall portion 211 provided with the pressure relief component 22 may be the end cover 213 of the outer shell 21, or may be a wall portion of the shell 212 of the outer shell 21. For example, in Figures 3 and 4, the first wall portion 211 is the end cover 213. Of course, the structure of the battery cell 20 is not limited thereto. In other embodiments, the first wall portion 211 may also be a wall portion of the shell 212 and the end cover 213 arranged opposite each other, that is, the bottom wall of the shell 212. The first wall portion 211 may also be a side wall of the shell 212 and the end cover 213 that are adjacent to and connected to each other. The side wall may be a wall arranged around the end cover 213 and forming the opening 2121.

[0160] 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 .

[0161] 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 Figures 3 and 4, the shell 212 is a cuboid structure, the length direction Y of the first wall portion is the length direction of the battery cell 20, the width direction Z of the first wall portion is the thickness direction of the battery cell 20, and the thickness direction X of the first wall portion is the height direction of the battery cell 20.

[0162] 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 formed at both opposite ends. 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 has openings 2121 on both 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.

[0163] The housing 21 may be made of various materials, such as copper, iron, aluminum, steel or aluminum alloy.

[0164] In some embodiments, the battery cell 20 further includes an electrode terminal 24 . The electrode terminal 24 may be insulated and mounted on the housing 21 , and the electrode terminal 24 is electrically connected to the electrode assembly 23 to output or input electrical energy to the battery cell 20 .

[0165] 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 .

[0166] The battery cell 20 may include one or two electrode terminals 24. For example, as shown in FIG4 , the battery cell 20 includes two electrode terminals 24, which are spaced apart along the length direction Y of the first wall portion. Each electrode assembly 23 has two tabs 231 spaced apart along the length direction Y of the wall portion. The two tabs 231 have opposite polarities, and the two electrode terminals 24 are electrically connected to the two tabs 231 of the electrode assembly 23 with opposite polarities, respectively, to enable input or output of the positive and negative electrodes of the battery cell 20.

[0167] It should be noted that one tab 231 of the electrode assembly 23 can be a component formed by stacking and connecting areas on the positive electrode sheet that are not coated with the positive electrode active material layer, forming a positive tab, and the other tab can be a component formed by stacking and connecting areas on the negative electrode sheet that are not coated with the negative electrode active material layer, forming a negative tab.

[0168] 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.

[0169] There are various locations where the electrode terminals 24 can be mounted on the outer shell 21. 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 the embodiment where the battery cell 20 includes two electrode terminals 24, both electrode terminals 24 can also be mounted on the shell 212 of the outer shell 21. Similarly, one electrode terminal 24 can be mounted on the shell 212 of the outer shell 21, and the other electrode terminal 24 can be mounted on the end cap 213 of the outer shell 21.

[0170] In some embodiments, as shown in Figure 4, the battery cell 20 may also include two current collecting components 25. The two current collecting components 25 are both arranged in the outer shell 21 and are spaced apart along the length direction Y of the first wall portion. Each current collecting component 25 is used to connect an electrode terminal 24 and a plurality of electrode assemblies 23 with the same polarity of the electrode lugs 231 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 electrode lugs 231 and the electrode terminal 24.

[0171] 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.

[0172] 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.

[0173] The pressure relief component 22 may have various structures. For example, as shown in FIG4 , the pressure relief component 22 may be a structure that is separate from the first wall portion 211 of the housing 21, or the pressure relief component 22 may be a structure that is integrally formed with the first wall portion 211 of the housing 21. When the pressure relief component 22 and the first wall portion 211 of the housing 21 are separate structures, that is, the first wall portion 211 of the housing 21 is provided with a pressure relief hole (not shown in the figure) for mounting the pressure relief component 22, and the pressure relief component 22 is connected to the first wall portion 211 and covers the pressure relief hole. The pressure relief component 22 and the first wall portion 211 may be connected in various ways, such as welding or clamping. When the pressure relief component 22 and the first wall portion 211 of the outer shell 21 are an integrally formed structure, the pressure relief component 22 is a wall of the outer shell 21, that is, the pressure relief component 22 is integrated on the first wall portion 211 and forms a wall of the outer shell 21. Correspondingly, the pressure relief component 22 is a weak structure formed on the first wall portion 211 for cracking when the battery cell 20 releases pressure.

[0174] Exemplarily, as shown in Figures 8 and 9, the pressure relief component 22 and the first wall portion 211 are an integrally formed structure, that is, the pressure relief component 22 is the first wall portion 211, and the first weak portion 221 and the predetermined pressure relief area P are both formed on the first wall portion 211.

[0175] The pressure relief component 22 includes a first weak portion 221, i.e., the first weak portion 221 is a portion of the pressure relief component 22. The first weak portion 221 is the area of ​​the pressure relief component 22 with the smallest thickness in the thickness direction X of the first wall portion. Therefore, the first weak portion 221 is more susceptible to rupture due to increased air pressure inside the battery cell 20 than other areas of the pressure relief component 22. The extension trajectory of the first weak portion 221 is the rupture trajectory of the pressure relief component 22. After at least a portion of the first weak portion 221 is ruptured, the pressure relief component 22 can open the predetermined pressure relief area P, allowing the battery cell 20 to release pressure inside the battery cell 20 from the predetermined pressure relief area P.

[0176] The first weak portion 221 defines at least one predetermined pressure relief area P, that is, the predetermined pressure relief area P is a portion of the pressure relief component 22. The first weak portion 221 can define one predetermined pressure relief area P. The first weak portion 221 can also define multiple predetermined pressure relief areas P, such as two predetermined pressure relief areas P, three predetermined pressure relief areas P, four predetermined pressure relief areas P, etc.

[0177] Depending on the structural shape of the first weak portion 221, the predetermined pressure relief area P is formed in different ways. For example, in some embodiments, along the extension direction of the first weak portion 221, the first weak portion 221 forms a closed structure, and the space enclosed by the first weak portion 221 is the predetermined pressure relief area P. For example, as shown in Figures 3 to 5, the extension trajectory of the first weak portion 221 is an ellipse, and the first weak portion 221 defines an elliptical predetermined pressure relief area P. In this embodiment, the area S of all predetermined pressure relief areas P is the area of ​​the area enclosed by the outer contour of the first weak portion 221. The outer contour of the first weak portion 221 is the contour of the edge of the first weak portion 221 closest to the first wall portion 211 in the width direction of the first weak portion 221.

[0178] In other embodiments, along the extension direction of the first weak portion 221, the first weak portion 221 is a non-enclosed structure, and the predetermined pressure relief zone P is defined by the first weak portion 221 and the line connecting the ends of the first weak portion 221. It should be noted that the line connecting the ends of the first weak portion 221 is a virtual line. For example, as shown in Figure 8, along the extension direction of the first weak portion 221, the first weak portion 221 is V-shaped. The predetermined pressure relief zone P is defined by the V-shaped first weak portion 221 and the line connecting the two ends of the V-shaped first weak portion 221. For example, as shown in Figure 9, along the extension direction of the first weak portion 221, the first weak portion 221 is U-shaped. The predetermined pressure relief zone P is defined by the U-shaped first weak portion 221 and the line connecting the two ends of the U-shaped first weak portion 221. In this case, the sum S of the areas of all predetermined pressure relief zones P is the area enclosed by the outer contour of the first weak portion 221 and the line connecting the ends of the first weak portion 221. The dashed lines shown in Figures 8 and 9 are lines connecting the ends of the first weak portion 221. The dashed line in Figure 11 is a line connecting the ends of the two first weak sections 2211 of the first weak portion 221 in the direction of their extension. These two dashed lines and the first weak portion 2211 together form two predetermined pressure relief areas P. The dashed line in Figure 17, parallel to the second groove 225, is a line connecting the ends of the two first weak sections 2211 of the first weak portion 221 in the direction of their extension. These two dashed lines and the first weak portion 2211 together form two predetermined pressure relief areas P.

[0179] The first weak portion 221 includes at least one first weak section 2211. It should be noted that the first weak section 2211 of the first weak portion 221 is a structure extending along a smooth trajectory, such as a straight line or an arc. The first weak section 2211 of the first weak portion 221 can be one or multiple. If the first weak portion 221 is a straight line, an arc, or an annular structure, the first weak portion 221 includes only one first weak section 2211. If the first weak portion 221 is a "V"-shaped structure, a "U"-shaped structure, or an "H"-shaped structure, the first weak portion 221 includes multiple first weak sections 2211. For example, in FIG5 , the pressure relief component 22 is provided with a first groove 222. The bottom wall of the first groove 222 forms the first weak portion 221. If the first groove 222 is an annular groove, the first weak portion 221 includes only one first weak section 2211. For another example, as shown in Figure 8, a first groove 222 is provided on the pressure relief component 22, and the bottom wall of the first groove 222 forms a first weak portion 221. The first groove 222 includes a first groove section 2221 and a second groove section 2222 connected to form a V-shaped first groove 222. The bottom wall of the first groove section 2221 and the bottom wall of the second groove section 2222 respectively form a first weak section 2211, and the first weak portion 221 includes two first weak sections 2211.

[0180] As shown in FIG9 , the pressure relief component 22 is provided with a first groove 222. The bottom wall of the first groove 222 forms a first weak portion 221. The first groove 222 includes a first groove section 2221, a second groove section 2222, and a third groove section 2223 connected to each other, forming a U-shaped first groove 222. The first groove section 2221 and the third groove section 2223 are arranged opposite each other, and the second groove section 2222 connects to the first groove section 2221. The bottom walls of the first groove section 2221, the second groove section 2222, and the third groove section 2223 each form a first weak section 2211. The first weak portion 221 includes three first weak sections 2211.

[0181] For another example, in Figure 10, a first groove 222 is provided on the pressure relief component 22, and the bottom wall of the first groove 222 forms a first weak portion 221. The first groove 222 includes a first groove section 2221, a second groove section 2222, a third groove section 2223 and a fourth groove section 2224. The first groove section 2221 and the third groove section 2223 are arranged opposite to each other, the second groove section 2222 connects the first groove section 2221 and the third groove section 2223, and the fourth groove section 2224 is located between the first groove section 2221 and the third groove section 2223, and the fourth groove section 2224 is connected to the second groove section 2222. Then, the bottom wall of the first groove section 2221, the bottom wall of the second groove section 2222, the bottom wall of the third groove section 2223 and the bottom wall of the fourth groove section 2224 all form a first weak section 2211, and the first weak portion 221 includes four first weak sections 2211.

[0182] The cross-sectional area S1 of the first weak section 2211 perpendicular to its extension direction is the product of the maximum width of the bottom surface of the first groove 222 and the minimum residual thickness of the first groove 222 . The minimum residual thickness of the first groove 222 is the thickness of the first weak portion 221 .

[0183] The dimension W of the first wall portion 211 along the width direction Z of the first wall portion may be the maximum dimension of the first wall portion 211 in the width direction. As shown in FIG10 , in some embodiments, along the width direction Z of the first wall portion, the housing 21 includes a first side wall 212 a and a second side wall 212 b that are oppositely disposed. The first side wall 212 a and the second side wall 212 b are respectively connected to opposite sides of the first wall portion 211 along the width direction. The dimension W of the first wall portion 211 along the width direction may be the distance between the outer surface of the first side wall 212 a and the outer surface of the second side wall 212 b along the width direction Z of the first wall portion.

[0184] Illustratively, W may be 10 mm, 12 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, etc.

[0185] For example, S1 may be 0.006 mm. 2 , 0.01mm 2 , 0.0104mm 2 , 0.015mm 2 , 0.02mm 2 , 0.0225mm 2 , 0.03mm 2 , 0.04mm 2 ,0.05mm2,0.0575mm2,0.06mm2,0.07mm2,0.075mm,0.08mm 2 , 0.09mm2 , 0.1mm 2 , 0.108mm 2 , 0.12mm 2 , 0.15mm 2 wait.

[0186] 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 1-11 and Comparative Examples 1-4. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all 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 ordinary technicians in this field without creative work are within the scope of protection of this application.

[0187] Example 1

[0188] 1. Preparation of Battery Cell 20

[0189] 1) Preparation of positive electrode

[0190] 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.

[0191] 2) Preparation of negative electrode sheet

[0192] 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.

[0193] 3) Preparation of electrolyte

[0194] 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.

[0195] 4) Isolation parts

[0196] A 16 μm polyethylene film was used as a separator.

[0197] 5) Preparation of battery cell 20

[0198] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator positioned between the positive and negative electrode sheets to separate them. The electrode assembly 23 is then wound and placed within an aluminum housing 21. The prepared electrolyte is injected into the dried housing 21. The battery cell 20 is then packaged, left to rest, formed, shaped, and subjected to capacity testing, completing the preparation of the battery cell 20. The housing 21 of the battery cell 20 is a rectangular parallelepiped structure. The shell 212 of the housing 21 is open at one end. The wall of the housing 212 opposite the end cap 213 is a first wall 211, which is a rectangular wall. A pressure relief component 22 is provided on the first wall 211 of the housing 21. The first wall 211 and the pressure relief component 22 are integrally formed. The pressure relief component 22 is provided with a first groove 222, so that the bottom wall of the first groove 222 forms a first weak portion 221. The first groove 222 is an H-shaped structure and a three-level notch. The first groove 222 is provided on the outer surface of the first wall portion 211. Among them, the area S1 of the cross section of the first weak section 2211 of the first weak portion 221 of the pressure relief component 22 of the battery cell 20 of Example 1 perpendicular to its extension direction is 0.006mm 2 , the dimension W of the first wall portion 211 along its width direction is 100 mm.

[0199] The manufacturing method of the battery cell 20 of Example 2-11 is the same as that of Example 1, except that the cross-sectional area S1 of the first weak section 2211 of the first weak portion 221 perpendicular to its extension direction and the dimension W of the first wall portion 211 along its width direction are different.

[0200] By performing fatigue tests on the battery cells 20 in Examples 1-7 and Comparative Examples 1-4, the number of fatigue cycles of the battery cells 20 during long-term use is obtained, and by performing thermal runaway tests on the battery cells 20, the breath holding time of the battery cells 20 during thermal runaway is obtained, thereby evaluating the reliability of the battery cells 20, as shown in Table 1.

[0201] The fatigue times of the battery cell 20 are measured as follows:

[0202] 1) Prepare a special test fixture. Specifically, the fixture consists of three 10mm steel plates (first steel plate, second steel plate, and third steel plate). Each steel plate can completely cover the large surface of the battery cell 20 (the large surface of the battery cell 20 refers to the outer surface of the shell 212 perpendicular to the width direction Z along the first 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 steel plate and the third steel plate, and the second steel plate is constrained by a guide rail. The second steel plate can only move horizontally in a direction perpendicular to the plane of the steel plate.

[0203] 2) The battery cell 20 is installed between the first steel plate and the second steel plate, and a support structure is placed between the large surface of one side of the battery cell 20 and the first steel plate, and the large surface of the other side and the second steel plate. The support structure can be an insulation pad or a water-cooling plate (consistent with the material / structure between two adjacent 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 large surface 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.

[0204] 3) Adjust the position of the second steel plate by adjusting the bolt preload to adjust the initial compressive force on the battery cell 20. Secure a battery cell 20 in a dedicated test fixture, adjust the bolt preload, and observe the pressure sensor until the initial compressive force on the battery cell 20 is 2000N. Then, connect the two electrical connections (positive and negative electrode terminals) of the battery cell 20 to the charging and discharging equipment.

[0205] 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.

[0206] 5) The test steps are carried out in accordance with Section 6.4 "Standard Cycle Life" of GBT31484-2015 "Requirements and Test Methods for 100 Cycle Life of Power Batteries for Electric Vehicles", and the test cycle end condition is changed to "stop testing until the first groove 222 provided on the pressure relief component 22 is damaged."

[0207] Specifically, test according to the following steps:

[0208] a) Discharge to 2.8V with a current of 1I1(A);

[0209] b) Leave it for no less than 30 minutes;

[0210] 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;

[0211] d) Leave it for no less than 30 minutes;

[0212] e) Discharge to 2.8V at a current of 1I1(A);

[0213] f) Repeat steps b) to e) until the first groove 222 of the pressure relief component 22 is damaged and the test is stopped.

[0214] That is, during the test, the area where the first groove 222 of the pressure relief component 22 of the battery cell 20 is located is continuously observed until the area breaks and leaks. The number of cycles is recorded as the cycle fatigue number of the battery cell 20. The more cycle fatigue numbers a battery cell 20 has, the lower the probability of the battery cell 20 opening the valve and leaking liquid due to gas production during long-term use, and the longer the battery cell 20's service life.

[0215] The thermal runaway test method for battery cell 20 is as follows:

[0216] 1. Select the heating plate according to the size of the battery cell 20. The size of the heating plate should cover as much surface of the battery cell 20 as possible (coverage area ≥ 60%).

[0217] 2. Charge the battery cell 20 to 100% SOC before testing and ensure that the temperature of the battery cell 20 is 25±5℃;

[0218] 3. Sensor layout:

[0219] 1) Arrangement of temperature-sensing wires: A layer of Teflon is applied to the center areas of the two large surfaces of the battery cell 20, and a temperature-sensing wire is arranged above the Teflon, followed by another layer of Teflon.

[0220] 2) Voltage sampling line layout: A layer of Teflon is applied to the positive electrode terminal, negative electrode terminal and housing 21 of the battery cell 20, and a voltage sampling line is arranged above the Teflon, followed by another layer of Teflon.

[0221] 3) Air pipe arrangement: Drill a hole in the first wall 211 of the housing 21 of the battery cell 20 along the length direction Y of the first wall. The drilling position is located at the center between the edge of the first groove 222 and the side surface of the housing 212 (the outer surface of the wall of the housing 212 adjacent to the first wall 211 along the length direction Y of the first wall). Insert the air pipe into the hole and seal it. Connect the air pipe to the air pressure sensor.

[0222] 4) 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 ≤0.1S;

[0223] 4. Assemble the fixture so that it completely covers the large surface of the battery cell 20 (the outer surface of the housing 212 perpendicular to the width direction Z of the first wall), with a clamping force of 3000N. Note: The arrangement order of the fixture, heating plate and battery cell is: fixture + heating plate + battery cell + fixture;

[0224] 5. Testing: Turn on the data acquisition instrument to collect temperature, voltage, and air pressure data, then turn on the heating plate at a power of 500W to heat the battery cell 20 until the battery cell thermal runaway occurs.

[0225] 6. Obtain the pressure holding time of the battery cell 20, determine the thermal runaway moment and valve opening moment based on the temperature, voltage, and air pressure data collected by the data acquisition instrument, and calculate the pressure holding time of the battery cell 20 based on the formula: pressure holding time = valve opening moment - thermal runaway moment.

[0226] Thermal runaway criteria: a) The triggering object generates a voltage drop exceeding 25% of the initial voltage; b) The temperature at the detection point reaches the manufacturer's maximum operating temperature; c) The temperature rise rate dT / dt at the detection point is ≥ 1°C / s and persists for more than 3 seconds. Thermal runaway is determined to have occurred when a) and c) or b) and c) occur, and the moment of thermal runaway is determined.

[0227] Valve opening timing determination: When the air pressure drops by more than 25%, it can be determined that the valve is open (at least partially cracked along the first weak portion 221). The moment when the air pressure begins to drop is the valve opening time. The valve opening time and thermal runaway time can both be obtained from the data logger.

[0228] Table 1:

[0229] As shown in Table 1, as W gradually decreases, the battery cell 20's holding time increases. Specifically, as W gradually decreases, the battery cell 20's timely pressure relief performance deteriorates, increasing the risk of explosion during thermal runaway. As W gradually decreases, the battery cell 20's fatigue cycle increases. Specifically, as W gradually decreases, the likelihood of a battery cell 20 leaking due to fatigue during long-term use decreases.

[0230] As S1 gradually increases, the battery cell 20's holding time shortens. Specifically, as S1 gradually increases, the battery cell 20's timely pressure relief performance deteriorates, increasing the risk of explosion during thermal runaway. As S1 gradually increases, the battery cell 20's fatigue cycles increase. Specifically, as S1 gradually increases, the likelihood of a battery cell 20 leaking due to fatigue during long-term use decreases.

[0231] In Table 1, when W is 4 mm, 6 mm and S1 is 0.2 mm 2 , 0.18mm 2When W is 10mm, 12mm, 20mm, 40mm, 60mm, 80mm, 100mm, 130mm, 150mm and S1 is 0.15mm, the holding time of battery cell 20 is 5.4s and 5.3s respectively, which is much longer than when W is 10mm, 12mm, 20mm, 40mm, 60mm, 80mm, 100mm, 130mm, 150mm and S1 is 0.15mm. 2 , 0.12mm 2 , 0.1mm 2 , 0.04mm 2 , 0.03mm 2 , 0.01mm 2 , 0.0026mm 2 , 0.002mm 2 The holding time of the battery cells in Comparative Examples 3 and 4 is much longer than the holding time of the battery cells 20 in Examples 1 to 7, Comparative Examples 1 and 2. Therefore, when W ≥ 10 mm and S1 ≤ 0.15 mm 2 When the pressure relief component 22 of the battery cell 20 is not in time to release the pressure, the possibility of timely pressure relief of the battery cell 20 can be increased, and the risk of bursting, explosion, fire, etc. of the shell 21 of the battery cell 20 caused by the untimely pressure relief component 22 is reduced.

[0232] When W is 150mm, 130mm and S1 is 0.002mm 2 , 0.0026mm 2 When W is 100mm, 80mm, 60mm, 40mm, 20mm, 12mm, 10mm, 6mm, 4mm and S1 is 0.006mm, the fatigue times of the battery cell 20 are 872 and 914 respectively, which are much smaller than when W is 100mm, 80mm, 60mm, 40mm, 20mm, 12mm, 10mm, 6mm, 4mm and S1 is 0.006mm. 2 , 0.01mm 2 , 0.03mm 2 , 0.04mm 2 , 0.1mm 2 , 0.12mm 2 , 0.15mm 2 , 0.18mm 2 , 0.2mm 2 The fatigue times of the battery cell 20 in Comparative Example 1 and Comparative Example 2 are much smaller than those in Examples 1 to 7, Comparative Example 3 and Comparative Example 4. Therefore, when W≤100mm and S1≥0.006mm 2 , which makes the battery cell 20 have a longer fatigue life, thereby reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 in the area corresponding to the first groove 222 after long-term use of the battery cell 20.

[0233] Therefore, 10mm≤W≤100mm and 0.006mm 2≤S1≤0.15mm 2 , which can take into account the reduction of risks such as bursting, explosion, and fire of the outer shell 21 of the battery cell 20 due to the untimely pressure relief of the pressure relief component 22, and the reduction of risks of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 at the corresponding position of the first groove 222 of the battery cell 20 after long-term use, thereby improving the use stability of the pressure relief component 22 and improving the service life and reliability of the battery cell 20.

[0234] Therefore, the dimension W of the first wall portion 211 along its width direction is 10 mm to 100 mm. The dimension of the first wall portion 211 along its width direction is set to be greater than or equal to 10 mm, thereby alleviating the phenomenon that the pressure-bearing capacity of the first weak section 2211 of the first weak portion 221 is too large, resulting in the pressure relief component 22 requiring too large an explosion pressure when the battery cell 20 is relieved of pressure. This can further reduce the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, thereby effectively improving the reliability of the battery cell 20. Setting the dimension of the first wall portion 211 along its width direction to be less than or equal to 100mm can reduce the deformation of the first weak section 2211 when the expansion force generated by the expansion of the battery cell 20 acts on the pressure relief component 22 during use, thereby reducing the phenomenon of the first weak section 221 of the pressure relief component 22 being reduced in structural strength due to excessive deformation, and further reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 in the first weak section 221 after long-term use of the battery cell 20, thereby further improving the stability of the pressure relief component 22 and the service life and reliability of the battery cell 20. The area of ​​the cross section of the first weak section 2211 perpendicular to its extension direction is limited to 0.006mm 2 to 0.15mm 2 , the cross-sectional area of ​​the first weak section 2211 perpendicular to its extension direction is set to be greater than or equal to 0.006mm 2 , which can reduce the deformation of the first weak section 2211 when the expansion force generated by the expansion of the battery cell 20 acts on the pressure relief component 22 during use, thereby reducing the phenomenon of reduced structural strength of the first weak section 221 of the pressure relief component 22 due to excessive deformation, and further reduce the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component at the first weak section 221 after long-term use of the battery cell 20, thereby further improving the stability of the pressure relief component 22 and further improving the service life and reliability of the battery cell 20. The area of ​​the cross section of the first weak section 2211 perpendicular to its extension direction is set to be less than or equal to 0.15mm 2, which can alleviate the phenomenon that the pressure-bearing capacity of the first weak section 2211 of the first weak part 221 is too large, resulting in the pressure relief component 22 requiring too large a bursting pressure when the battery cell 20 is depressurized. This can further reduce the risk of bursting, explosion, fire, etc. of the battery cell 20 shell caused by the untimely pressure relief component 22, thereby effectively improving the reliability of the battery cell 20.

[0235] In some embodiments, 20 mm ≤ W ≤ 80 mm, 0.01 mm 2 ≤S1≤0.1mm 2 .

[0236] Illustratively, W can be 20 mm, 25 mm, 35 mm, 45 mm, 55 mm, 65 mm, 75 mm, 80 mm, etc.

[0237] For example, S1 may be 0.01 mm. 2 , 0.015mm 2 , 0.025mm 2 , 0.035mm 2 , 0.045mm 2 , 0.055mm 2 , 0.065mm 2 , 0.075mm 2 , 0.085mm 2 , 0.095mm 2 , 0.1mm 2 wait.

[0238] Please continue to refer to Table 1. When W is 20mm, 40mm, 60mm, 80mm, 100mm, the relative values ​​when W is 10mm and 12mm and S1 is 0.1mm are 2 , 0.04mm 2 , 0.03mm 2 , 0.01mm 2 , 0.006mm 2 0.15mm relative to S1 2 , 0.12mm 2 When W≥20mm2 and S1≤0.1mm2, the risk of explosion of the battery cell 20 due to thermal runaway can be further reduced.

[0239] When W is 10mm, 12mm, 20mm, 40mm, 60mm, and 80mm relative to when W is 100mm, and when S1 is 0.15mm2, 0.12mm2, 0.1mm2, 0.04mm2, 0.03mm2, and 0.01mm2 relative to when S1 is 0.006mm2, the fatigue times of the battery cell 20 are greater, that is, the risk of valve opening and leakage during long-term use of the battery cell 20 is lower. Therefore, when W≤80mm2 and S1≥0.01mm2, the risk of valve opening and leakage during long-term use of the battery cell 20 can be further reduced.

[0240] Therefore, the dimension of the first wall portion 211 along its width direction is further limited to 20 mm to 80 mm, and the dimension of the first wall portion 211 along its width direction is set to be greater than or equal to 20 mm, thereby further alleviating the phenomenon that the pressure-bearing capacity of the first weak section 2211 of the first weak portion 221 is too large, resulting in excessive bursting pressure required by the pressure relief component 22 when the battery cell 20 is depressurized. This can further reduce the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, thereby effectively improving the reliability of the battery cell 20. Setting the dimension of the first wall portion 211 along its width direction to be less than or equal to 80 mm can further reduce the deformation of the first weak section 2211 when the expansion force generated by the expansion of the battery cell 20 acts on the pressure relief component 22 during use, thereby reducing the phenomenon of reduced structural strength of the first weak portion 221 of the pressure relief component 22 due to excessive deformation, and further reducing the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component 22 in the first weak portion 221 after long-term use of the battery cell 20, thereby further improving the use stability of the pressure relief component 22 and further improving the service life and reliability of the battery cell 20. And further limiting the area of ​​the cross section of the first weak section 2211 perpendicular to its extension direction to 0.01mm2 to 0.1mm2, setting the area of ​​the cross section of the first weak section 2211 perpendicular to its extension direction to be greater than or equal to 0.01mm2, can further reduce the deformation of the first weak section 2211 when the expansion force generated by expansion during the use of the battery cell 20 acts on the pressure relief component 22, thereby reducing the structural strength reduction of the first weak portion 221 of the pressure relief component 22 due to excessive deformation, and further reducing the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component 22 in the first weak portion 221 after long-term use of the battery cell 20, so as to further improve the use stability of the pressure relief component 22 and further improve the service life and reliability of the battery cell 20. Setting the area of ​​the cross section of the first weak section 2211 perpendicular to its extension direction to be less than or equal to 0.1 mm2 can alleviate the phenomenon that the pressure-bearing capacity of the first weak section 2211 of the first weak portion 221 is too large, resulting in the pressure relief component 22 requiring too large a bursting pressure when releasing pressure from the battery cell 20. This can further reduce the risk of bursting, explosion, fire, etc. in the outer shell 21 of the battery cell 20 due to untimely pressure relief from the pressure relief component 22, thereby effectively improving the reliability of the battery cell 20.

[0241] In some embodiments, the ratio of the cross-sectional area S1 of the first weak section 2211 perpendicular to its extension direction to the dimension W of the first wall portion 211 along its width direction is defined as 0.00004 to 0.02, ie, 0.00004≤S1 / W≤0.02.

[0242] The ratio of the area S1 of the cross section of the first weak section 2211 perpendicular to its extension direction to the dimension W of the first wall portion 211 along its width direction, that is, S1 / W, can be 0.00004, 0.00005, 0.00006, 0.000089, 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.000125, 0.00029, 0.0005, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.015, 0.02, etc.

[0243] Therefore, by setting the ratio of the cross-sectional area of ​​the first weak section 2211 of the first weak portion 221 perpendicular to its extension direction to the dimension of the first wall portion 211 along its width direction to 0.00004 to 0.02, and setting the ratio to be greater than or equal to 0.00004, when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22, the concentration of stress in the first weak section 2211 of the first weak portion 221 can be reduced, and the predetermined pressure relief area P can absorb a part of the expansion force, thereby effectively alleviating the first weak portion 221 of the pressure relief component 22. The ratio is set to be less than or equal to 0.02 to mitigate the phenomenon that the pressure relief component 22 requires an excessive burst pressure when releasing pressure from the battery cell 20 due to the excessive pressure bearing capacity of the first weak section 2211. This reduces the risk of premature actuation or fatigue cracking of the pressure relief component 22 at the first weak section 2211 after long-term use of the battery cell 20, leading to leakage.

[0244] In some embodiments, 0.00006≤S1 / W≤0.015.

[0245] Illustratively, S1 / W may be 0.00006, 0.00015, 0.00025, 0.00035, 0.00045, 0.00055, 0.00065, 0.00075, 0.00085, 0.00095, 0.001, 0.0015, 0.0025, 0.0035, 0.0045, 0.005, 0.0065, 0.0075, 0.008, 0.0095, 0.015, etc.

[0246] The ratio of the cross-sectional area of ​​the first weak section 2211 perpendicular to its extension direction to the dimension of the first wall portion 211 along its width direction is set to 0.00006 to 0.015. The ratio of the cross-sectional area of ​​the first weak section 2211 perpendicular to its extension direction to the dimension of the first wall portion 211 along its width direction is greater than or equal to 0.00006. This can further reduce the deformation of the first weak section 2211 when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22, thereby reducing the structural strength reduction of the first weak portion 221 of the pressure relief component 22 due to excessive deformation, and further reduce the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 at the first weak portion 221 after long-term use of the battery cell 20, thereby further improving the use stability of the pressure relief component 22 and further improving the service life and reliability of the battery cell 20. The ratio of the area of ​​the cross section of the first weak section 2211 perpendicular to its extension direction to the dimension of the first wall portion 211 along its width direction is less than or equal to 0.015, which further alleviates the phenomenon that the pressure-bearing capacity of the first weak section 2211 of the first weak portion 221 is too large, resulting in excessive bursting pressure required by the pressure relief component 22 when the battery cell 20 is depressurized. This can further reduce the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, thereby effectively improving the reliability of the battery cell 20.

[0247] In some embodiments, the pressure relief component 22 is provided with a first groove 222, the first groove 222 includes at least one groove section, and the pressure relief component 22 forms at least one first weak section 2211 in the area where the groove section is provided. The width of the bottom surface of the groove section is A, in mm, and the thickness of the first weak section 2211 is H, in mm, satisfying: S1 = A × H; 0.1 mm ≤ A ≤ 0.3 mm, 0.06 mm ≤ H ≤ 0.5 mm.

[0248] The width of the bottom surface of the groove section is A, which can be the dimension of the bottom surface of the groove section in the width direction. The thickness of the first weak section 2211 is the dimension of the first weak section 2211 along the thickness direction X of the first wall portion.

[0249] A rounded corner or chamfered transition is formed at the corner of the bottom surface and the side surface of the groove section. When measuring the width A of the bottom surface of the groove section, the size of the chamfered corner should be removed. In other words, the cross-sectional area of ​​the first weak section 2211 is calculated by multiplying the width of the bottom surface of the groove section by the thickness of the first weak section 2211 formed corresponding to the groove section. When measuring the width of the bottom surface of the groove section and the thickness of the first weak section 2211 formed corresponding to the groove section, measurements should be made in other areas other than the rounded corner or chamfer between the side surface and the bottom surface of the groove.

[0250] If the slot segment has rounded corners or chamfers at both ends in the extension direction, the cross-sectional area of ​​the first weak section 2211 is calculated by multiplying the width of the slot bottom surface and the thickness of the first weak section 2211 formed corresponding to the slot segment. When measuring the width of the slot bottom surface and the thickness of the first weak section 2211 formed corresponding to the slot segment, measurements should be made in other areas of the slot segment other than the rounded corners or chamfers at both ends in the extension direction.

[0251] Illustratively, the width A of the groove bottom surface of the groove segment may be 0.1 mm, 0.13 mm, 0.15 mm, 0.17 mm, 0.19 mm, 0.2 mm, 0.23 mm, 0.25 mm, 0.27 mm, 0.29 mm, 0.3 mm, etc.

[0252] For example, the thickness H of the first weak section 2211 may be 0.06 mm, 0.08 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, etc.

[0253] 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 8-12. 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.

[0254] The preparation methods of the battery cells 20 of Examples 8-12 are the same as those of Example 1. The differences between the battery cells 20 of Examples 8-12 are the width A of the bottom wall of the groove section and the thickness H of the first weak section 2211 , as shown in Table 2.

[0255] Table 2:

[0256] As shown in Table 2, as A gradually increases, the fatigue frequency of the battery cell 20 gradually increases, and the possibility of leakage due to valve opening during long-term use of the battery cell 20 gradually decreases. As A gradually increases, the duration of the battery cell 20 holding its breath gradually increases, and the possibility of the pressure relief component 22 of the battery cell 20 releasing pressure in a timely manner gradually decreases, and the risk of explosion of the battery cell 20 during thermal runaway gradually increases.

[0257] As H gradually increases, the fatigue frequency of the battery cell 20 gradually increases, and the possibility of leakage due to valve opening during long-term use of the battery cell 20 gradually decreases. As H gradually increases, the duration of the battery cell 20 holding its breath gradually increases, and the possibility of the pressure relief component 22 of the battery cell 20 releasing pressure in time gradually decreases, and the risk of explosion of the battery cell 20 during thermal runaway gradually increases.

[0258] Combining Tables 1 and 2, it can be seen that when the width A of the bottom surface of the groove section is greater than or equal to 0.1 mm and the thickness H of the first weak portion 221 is greater than or equal to 0.06 mm, the number of fatigue times of the battery cell 20 is greater than or equal to 1253, so that the battery cell 20 has a relatively high fatigue life, thereby reducing the possibility of premature actuation or fatigue cracking of the pressure relief component 22 during use. This is beneficial to reducing the possibility of the pressure relief component 22 opening and leaking during long-term use of the battery cell 20, and is beneficial to increasing the service life of the battery cell 20.

[0259] When the width A of the bottom surface of the groove section is less than or equal to 0.3 mm and the thickness H of the first weak portion 221 is less than or equal to 0.5 mm, the holding time of the battery cell 20 is less than or equal to 3.2 s, and the probability of the battery cell 20 exploding, bursting, or catching fire in the event of thermal runaway is relatively low, thereby reducing the risk of bursting, explosion, or fire in the battery cell 20 due to untimely pressure relief of the pressure relief component 22, thereby effectively improving the reliability of the battery cell 20.

[0260] Therefore, the area S1 of the cross section of the first weak section 2211 of the first weak portion 221 perpendicular to its extension direction is the product of the width A of the groove bottom of the groove section and the thickness H of the first weak portion 221. The width A of the groove bottom of the groove section is set to 0.1 mm to 0.3 mm, and the thickness H of the first weak portion 221 is set to 0.06 mm to 0.5 mm. By setting the width A of the groove bottom of the groove section to be greater than or equal to 0.1 mm and the thickness H of the first weak portion 221 to be greater than or equal to 0.06 mm, the concentration of stress generated by the expansion of the battery cell 20 in the first weak section 2211 of the first weak portion 221 can be reduced, and the stress absorption effect of the predetermined pressure relief area P can be improved, thereby further reducing the strain and strain amplitude of the first weak section 221 of the pressure relief component 22, and further reducing the risk of premature actuation or fatigue cracking of the pressure relief component 22 during use of the battery cell 20. By setting the width A of the bottom surface of the groove section to less than or equal to 0.3 mm and the thickness H of the first weak portion 221 to less than or equal to 0.5 mm, the bursting pressure required by the pressure relief component 22 during pressure relief can be reduced, thereby further reducing the risk of bursting, explosion, fire, etc. in the outer shell 21 of the battery cell 20 due to untimely pressure relief by the pressure relief component 22.

[0261] In some embodiments, 0.15 mm ≤ A ≤ 0.25 mm; 0.1 mm ≤ H ≤ 0.3 mm.

[0262] Continuing to refer to Table 2, when the width A of the bottom surface of the groove section is greater than or equal to 0.15 mm and the thickness H of the first weak portion 221 is greater than or equal to 0.1 mm, the fatigue times of the battery cell 20 are greater, thereby improving the fatigue life of the battery cell 20 and further reducing the risk of valve opening and leakage during long-term use of the battery cell 20.

[0263] When the width A of the bottom surface of the groove section is less than or equal to 0.25 mm and the thickness H of the first weak portion 221 is less than or equal to 0.3 mm, the holding time of the battery cell 20 is shorter. Therefore, when A≤0.25 mm and H≤0.3 mm, the battery cell 20 has a shorter holding time, and the risk of explosion during thermal runaway of the battery cell 20 is lower.

[0264] Therefore, by setting the groove bottom width A to be greater than or equal to 0.15 mm and the first weak portion 221 thickness H to be greater than or equal to 0.1 mm, the concentration of stress generated by expansion of the battery cell 20 in the first weak section 2211 of the first weak portion 221 can be further reduced, and the stress absorption efficiency of the predetermined pressure relief area P can be further enhanced, thereby further reducing the strain and strain amplitude of the first weak portion 221 of the pressure relief component 22, and further reducing the risk of premature actuation or fatigue cracking of the pressure relief component 22 during use of the battery cell 20. By setting the groove bottom width A to be less than or equal to 0.25 mm and the first weak portion 221 thickness H to be less than or equal to 0.3 mm, the burst pressure required by the pressure relief component 22 during pressure relief can be further reduced, thereby further reducing the risk of bursting, explosion, or fire in the battery cell 20 housing 21 due to untimely pressure relief from the pressure relief component 22.

[0265] As shown in FIG. 12 and FIG. 13 , along the thickness direction X of the first wall portion, the maximum groove depth of the first groove 222 is H1 , the thickness of the pressure relief component 22 is D, and 0.16≤H1 / D<1.

[0266] H1 / D can take any point value among 0.16, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, 0.5, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 0.99, etc., or a range of values ​​between any two of them.

[0267] It is understandable that if the pressure relief component 22 and the first wall portion 211 are integrally formed, the first wall portion 211 can serve as the pressure relief component 22 , and the thickness of the pressure relief component 22 is the same as the thickness of the first wall portion 211 .

[0268] In this embodiment, 0.16≤H1 / D<1, so that the maximum depth of the first groove 222 accounts for a small proportion of the thickness of the pressure relief component 22, and the bursting pressure of the battery cell 20 is not too high, which is conducive to improving the timeliness of the pressure relief of the battery cell 20.

[0269] In some embodiments, 0.4 mm ≤ H1 ≤ 2 mm, and 0.8 mm ≤ D ≤ 2.5 mm.

[0270] H1 can take any point value among 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 any range value between any two of them.

[0271] D can be any point value among 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 value between any two of them.

[0272] In this embodiment, 0.4 mm ≤ H1 ≤ 2 mm, and 0.8 mm ≤ D ≤ 2.5 mm, keeping the maximum depth of the first groove 222 and the thickness of the pressure relief component 22 within a reasonable range, resulting in better economic efficiency. In an embodiment where the first wall 211 serves as the pressure relief component 22, the thickness of the first wall 211 is 0.8 mm to 2.5 mm. A thickness of 0.8 mm or greater ensures sufficient strength for the first wall 211. A thickness of 2 mm or less ensures that the first wall 211 is not excessively thick. Given a given volume of the housing 21, the internal space of the housing 21 can be increased to create more space for the electrode assembly 23. While maintaining the thickness of the first wall 211 within the range of 0.8 mm to 2.5 mm, the maximum depth of the first groove 222 is controlled within the range of 0.4 mm to 2 mm, ensuring a better match between the maximum depth of the first groove 222 and the thickness of the pressure relief component 22, thereby ensuring good pressure relief capability for the pressure relief component 22.

[0273] In some embodiments, the pressure relief component 22 has a first surface 223 and a second surface 224 arranged opposite to each other in the thickness direction X of the first wall portion, and the first groove 222 is a multi-level notch groove, which is arranged in sequence from the first surface 223 to the second surface 224. In the two adjacent notch grooves, the first-level notch groove away from the first surface 223 is arranged at the bottom surface of the first-level notch groove close to the first surface 223.

[0274] That is, the pressure relief component 22 is formed with a multi-level stepped groove structure arranged sequentially from the first surface 223 to the second surface 224, and the stepped groove structure can be formed by one or more stamping operations or multiple etching operations.

[0275] In the embodiment where the first groove 222 includes a plurality of groove segments, each groove segment may also be a multi-level scoring groove structure.

[0276] By setting the first groove 222 as a stepped groove structure arranged along the thickness direction X of the first wall portion, so that the first groove 222 is a groove formed by multiple processing, adopting this structure, when forming the first weak portion 221 of the same thickness, on the one hand, the depth of the single processing of the notched groove can be reduced, which is beneficial to reducing the manufacturing difficulty and demand for manufacturing equipment for forming the first weak portion 221 of the same thickness, thereby reducing manufacturing costs, and can reduce the forming force that the pressure relief component 22 is subjected to during a single processing during the formation of the first weak portion 221, which is beneficial to reducing the risk of cracks in the pressure relief component 22, thereby improving the production quality of the battery cell 20, and on the other hand, it can improve the flow morphology of the first weak portion 221 during the formation process, which is beneficial to the flow of the material generated when forming the first weak portion 221, thereby improving the consistency of the structure of the multi-stage notched groove.

[0277] In the embodiment where the first groove 222 includes a plurality of groove segments, each groove segment may also be a three-level scoring groove structure.

[0278] For example, as shown in Figures 11 to 16, the first groove 222 includes three levels of scored grooves, which are arranged in sequence from the first surface 223 to the second surface 224. The three levels of scored grooves can be defined as a first sub-groove 222a, a second sub-groove 222b, and a third sub-groove 222c, respectively. The first sub-groove 222a, the second sub-groove 222b, and the third sub-groove 222c are arranged in sequence from the first surface 223 to the second surface 224. The second sub-groove 222b is provided at the bottom surface of the first sub-groove 222a, and the third sub-groove 222c is provided at the bottom surface of the second sub-groove 222b.

[0279] Exemplarily, as shown in Figures 11 to 16, in an embodiment where the first groove 222 includes a first groove segment 2221, a second groove segment 2222 and a third groove segment 2223, the first sub-groove 222a includes a first segment 222a1, a second segment 222a2 and a third segment 222a3, the second sub-groove 222b includes a fourth segment 222b1, a fifth segment 222b2 and a sixth segment 222b3, and the third sub-groove 222c includes a seventh segment 222c1, an eighth segment 222c2 and a ninth segment 222c3. The fourth section 222b1 is arranged on the bottom surface of the groove of the first section 222a1, the seventh section 222c1 is arranged on the bottom surface of the groove of the fourth section 222b1, and the first section 222a1, the fourth section 222b1 and the seventh section 222c1 together form the first groove section 2221; the fifth section 222b2 is arranged on the bottom surface of the groove of the second section 222a2, the eighth section 222c2 is arranged on the bottom surface of the groove of the fifth section 222b2, the second section 222a2, the fifth section 222b2 and the eighth section 222c2 together form the second groove section 2222; the sixth section 222b3 is arranged on the bottom surface of the groove of the third section 222a3, the ninth section 222c3 is arranged on the bottom surface of the groove of the sixth section 222b3, and the third section 222a3, the sixth section 222b3 and the ninth section 222c3 together form the third groove section 2223.

[0280] The first groove 222 includes a three-level scoring groove. When forming a first weak portion 221 of the same thickness, it can reduce the depth of the scoring groove in a single processing, which is beneficial to reducing the manufacturing difficulty and demand for manufacturing equipment for forming a first weak portion 221 of the same thickness, thereby reducing manufacturing costs. It can also reduce the forming force that the pressure relief component 22 is subjected to in a single processing during the formation of the first weak portion 221, which is beneficial to reducing the risk of cracks in the pressure relief component 22, thereby improving the production quality of the battery cell 20. On the other hand, it can improve the flow morphology of the first weak portion 221 during the formation process, which is beneficial to the flow of materials generated when forming the first weak portion 221, thereby improving the structural consistency of the multi-level scoring groove; it also alleviates the problem of increased processing time due to multiple processing required to form the first weak portion 221.

[0281] Of course, in other embodiments, the pressure relief component 22 may also be provided with a secondary scoring groove, a quaternary scoring groove, a quintuple scoring groove, or a VI scoring groove.

[0282] As shown in FIG. 17 to FIG. 20 , in some embodiments, the pressure relief component 22 further includes a second weak portion 228 , and the second weak portion 228 is configured to guide the predetermined pressure relief area P to open.

[0283] Specifically, along the thickness direction X of the first wall portion, the thickness of the second weak portion 228 can be greater than the thickness of the first weak portion 221. Specifically, the thickness of the second weak portion 228 is greater than the thickness of the first weak section 2211 of the first weak portion 221. The second weak portion 228 is configured to guide the predetermined pressure relief area P to flip when the first weak portion 221 ruptures, thereby relieving the internal pressure of the battery cell 20. As shown in Figures 18-20, the thickness of the second weak portion 228 is M, where M>H.

[0284] The thickness of the second weak portion 228 is greater than that of the first weak portion 221, so that the pressure relief component 22 can preferentially rupture along the first weak portion 221 and open the predetermined pressure relief area P. The second weak portion 228 is configured to guide the predetermined pressure relief area P to flip when the first weak portion 221 ruptures. In other words, after the first weak portion 221 ruptures, the predetermined pressure relief area P can flip around the second weak portion 228 as the flipping axis, so that after the predetermined pressure relief area P flips, the interior and exterior of the housing 21 are connected to each other and pressure relief is performed.

[0285] The second weak portion 228 can guide the predetermined pressure relief area P to open, thereby improving the opening effect of the predetermined pressure relief area P 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 P 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, connection failure, etc. caused by untimely pressure relief of the battery cell 20, which is beneficial to improving the reliability of the battery cell 20.

[0286] There are many ways to form the second weak portion 228 . For example, in some embodiments, the pressure relief component 22 is provided with a second groove 225 , and the pressure relief component 22 forms the second weak portion 228 in the area where the second groove 225 is provided.

[0287] It can be understood that the bottom wall of the second groove 225 forms the second weak portion 228. In other words, the portion of the pressure relief component 22 where the second groove 225 is provided and corresponding to the bottom surface of the second groove 225 serves as the second weak portion 228. Of course, in other embodiments, the second weak portion 228 can also have other structures. For example, the second weak portion 228 can be formed by heat treating a portion of the pressure relief component 22 to weaken the strength of the region.

[0288] The pressure relief component 22 is provided with a second groove 225, so that the pressure relief component 22 forms a second weak portion 228 in the area corresponding to the second groove 225. The battery cell 20 adopting this structure facilitates the formation of the second weak portion 228 on the pressure relief component 22, which is beneficial to reducing the difficulty of forming the second weak portion 228 on the pressure relief component 22, thereby improving the production efficiency of the battery cell 20.

[0289] In some embodiments, the second groove 225 is disposed on a surface of the pressure relief component 22 facing the interior of the housing 21 .

[0290] The surface of the pressure relief component 22 facing the interior of the housing 21 is the surface of the pressure relief component 22 facing the electrode assembly 23. The second groove 225 is provided on the surface of the pressure relief component 22 facing the interior of the housing 21. In other words, the second groove 225 is provided on the surface of the pressure relief component 22 facing the electrode assembly 23. The second groove 225 is recessed from the surface of the pressure relief component 22 facing the electrode assembly 23 in a direction away from the electrode assembly 23.

[0291] For example, in FIG17 , the second groove 225 is a strip-shaped structure and is parallel to the second groove section 2222 , so that the second weak portion 228 is a strip-shaped structure, thereby facilitating the predetermined pressure relief area P to flip around the second weak portion 228 after being opened.

[0292] By arranging the second groove 225 on the surface of the pressure relief component 22 facing the interior of the shell 21, the predetermined pressure relief area P can be flipped toward the outside of the shell 21 around the bottom wall of the second groove 225 when it is opened, thereby reducing the interference effect of the groove side surface of the second groove 225 on the predetermined pressure relief area P during the flipping process, which is beneficial to improving the flipping effect of the predetermined pressure relief area P.

[0293] Of course, in other embodiments, the second groove 225 may also be disposed on the side of the pressure relief component 22 facing away from the electrode assembly 23 .

[0294] As shown in Figures 19 and 20, in some embodiments, the pressure relief component 22 has a first surface 223 and a second surface 224 that are relatively arranged in the thickness direction X of the first wall portion, the first surface 223 is provided with a first groove 222, and the pressure relief component 22 forms a first weak portion 221 in the area where the first groove 222 is provided, and the second surface 224 is provided with a second groove 225, and the pressure relief component 22 forms a second weak portion 228 in the area where the second groove 225 is provided.

[0295] The first surface 223 and the second surface 224 are surfaces on opposite sides of the pressure relief component 22 in the thickness direction X of the first wall. The first groove 222 and the second groove 225 are respectively provided on both sides of the pressure relief component 22 along the thickness direction of the first wall.

[0296] Exemplarily, the first groove 222 is arranged on the surface of the pressure relief component 22 facing away from the interior of the housing 21, and the second groove 225 is arranged on the surface of the pressure relief component 22 facing the interior of the housing 21, so that the first groove 222 and the second groove 225 are respectively arranged on both sides of the pressure relief component 22.

[0297] By respectively arranging the first groove 222 and the second groove 225 on the first surface 223 and the second surface 224 opposite to each other along the thickness direction X of the first wall portion of the pressure relief component 22, it is convenient to process the first groove 222 and the second groove 225 on both sides of the pressure relief component 22 along the thickness direction X of the first wall portion, which is beneficial to reduce the mutual influence of the first groove 222 and the second groove 225 during the processing.

[0298] In some embodiments, the first surface 223 is the surface of the pressure relief component 22 facing away from the interior of the housing 21 , and the second surface 224 is the surface of the pressure relief component 22 facing the interior of the housing 21 .

[0299] That is, the first groove 222 is provided on the surface of the pressure relief component 22 facing away from the interior of the housing 21, and the first groove 222 is recessed from the first surface 223 toward the second surface 224. The second groove 225 is provided on the surface of the pressure relief component 22 facing the interior of the housing 21, and the second groove 225 is recessed from the second surface 224 toward the first surface 223.

[0300] By disposing the first groove 222 and the second groove 225, respectively, on the first surface 223 and the second surface 224 of the pressure relief component 22, which are opposite to each other along the thickness direction X of the first wall, it is convenient to process the first groove 222 and the second groove 225 on both sides of the pressure relief component 22 along the thickness direction X of the first wall, thereby reducing the mutual influence between the first groove 222 and the second groove 225 during the processing. In addition, the second groove 225 is disposed on the second surface 224 of the pressure relief component 22 facing the interior of the housing 21, so that the predetermined pressure relief area P, after being opened, can be flipped around the bottom wall of the second groove 225 toward the outside of the housing 21. This can reduce the interference caused by the groove side surface of the second groove 225 on the predetermined pressure relief area P during the flipping process, thereby improving the flipping effect of the predetermined pressure relief area P.

[0301] In some embodiments, along the thickness direction X of the first wall portion, a projection of the first groove 222 does not contact a projection of the second groove 225 .

[0302] It is understood that the first groove 222 and the second groove 225 do not intersect. In an embodiment where the pressure relief component 22 is provided with a multi-stage scored groove, and the first-stage scored groove farthest from the first surface 223 among the multi-stage scored grooves is the first groove 222, the second groove 225 may also not intersect with the first-stage scored groove closest to the first surface 223 among the multi-stage scored grooves.

[0303] By setting the projection of the first groove 222 in the thickness direction X of the first wall portion and the projection of the second groove 225 in the thickness direction X of the first wall portion to a non-contact structure, on the one hand, the mutual influence of the first groove 222 and the second groove 225 during the processing process can be reduced; on the other hand, the phenomenon of the first weak portion 221 causing the second weak portion 228 to crack when the first weak portion 221 cracks to release pressure can be reduced, and the stress influence between the first weak portion 221 and the second weak portion 228 can be reduced.

[0304] In an embodiment where the first groove 222 includes multiple groove segments, a first weak section 2211 is formed in the region corresponding to each groove segment. For example, the pressure relief component 22 is provided with a first groove 222, and the pressure relief component 22 forms a first weak portion 221 in the region where the first groove 222 is provided; the first groove 222 includes a first groove segment 2221 and a second groove segment 2222 connected thereto, and the pressure relief component 22 forms a first weak section 2211 in the region of the first groove segment 2221, and a first weak section 2211 in the region corresponding to the second groove segment 2222.

[0305] The first groove section 2221 can extend along a straight line. The second groove section 2222 can extend along a straight line. The first groove section 2221 and the second groove section 2222 together define at least one predetermined pressure relief area P. The predetermined pressure relief area P is configured to be opened when the pressure relief component 22 ruptures along at least a portion of the first weak portion 221 to release pressure within the battery cell 20.

[0306] The first slot section 2221 may also extend along a curve, for example, the first slot section 2221 is an arc section. The second slot section 2222 may also extend along a curve, for example, the second slot section 2222 is an arc section.

[0307] The first slot section 2221 and the second slot section 2222 each form a first weak section 2211, and the first weak portion 221 can include two first weak sections 2211. Because the first slot section 2221 and the second slot section 2222 are connected, the first weak section 2211 formed in the first slot section 2221 region and the first weak section 2211 formed in the second slot section 2222 region are connected, forming a first weak portion 221 comprising two connected first weak sections 2211. When one first weak section 2211 begins to rupture, it can drive the rupture of the other first weak section 2211, facilitating the rapid rupture of the first weak section 221, thereby opening the predetermined pressure relief zone P and achieving rapid pressure relief.

[0308] The first groove section 2221 and the second groove section 2222 jointly define a predetermined pressure relief area P, that is, the first groove section 2221 and the second groove section 2222 are structures arranged along the edge of the predetermined pressure relief area P, so that the setting trajectory of the first groove 222 is set along the edge of the predetermined pressure relief area P.

[0309] The predetermined pressure relief area P 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 221, that is, when the battery cell 20 undergoes thermal runaway and releases internal pressure, the areas of the first groove section 2221 and the second groove section 2222 of the pressure relief component 22 can be cracked, so that the predetermined pressure relief area P can be opened and the internal pressure of the battery cell 20 can be released.

[0310] The first slot segment 2221 and the second slot segment 2222 can be connected in various forms, for example, the first slot segment 2221 and the second slot segment 2222 are connected to form a "T" shape, the first slot segment 2221 and the second slot segment 2222 are connected to form a "V" shape, the first slot segment 2221 and the second slot segment 2222 are connected to form an "L" shape, the first slot segment 2221 and the second slot segment 2222 are connected to form an "X" shape, etc.

[0311] The first groove 222 includes a first groove section 2221 and a second groove section 2222, and the first groove section 2221 and the second groove section 2222 are interconnected structures. On the one hand, they 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, the position where the first groove section 2221 and the second groove section 2222 are interconnected is weaker, which is easier to crack and open the predetermined pressure relief area P to release the internal pressure of the battery cell 20.

[0312] As shown in Figure 17, in some embodiments, the first groove 222 includes a third groove section 2223, the first groove section 2221 and the third groove section 2223 are arranged opposite to each other, the second groove section 2222 connects the first groove section 2221 and the third groove section 2223, and the pressure relief component 22 forms a first weak section 2211 in the area corresponding to the third groove section 2223.

[0313] The third groove section 2223 may extend in a straight line. The first groove section 2221, the second groove section 2222, and the third groove section 2223 collectively define a predetermined pressure relief area P. The predetermined pressure relief area P is configured to be opened when the pressure relief component 22 is ruptured along at least a portion of the first weak portion 221 to release the internal pressure of the battery cell 20.

[0314] The extending direction of the first slot segment 2221 is parallel to the extending direction of the third slot segment 2223. The extending direction of the first slot segment 2221 is perpendicular to the extending direction of the second slot segment 2222. The extending direction of the third slot segment 2223 is perpendicular to the extending direction of the second slot segment 2222. In other words, the first slot segment 2221 and the third slot segment 2223 are respectively perpendicular to the second slot segment 2222.

[0315] The first slot segment 2221, the second slot segment 2222 and the third slot segment 2223 can be connected in various forms, for example, the first slot segment 2221, the second slot segment 2222 and the third slot segment 2223 are connected to form an "H" shape, or the first slot segment 2221, the second slot segment 2222 and the third slot segment 2223 are connected to form a "U" shape.

[0316] In other embodiments, the third slot segment 2223 may also extend along a curve, for example, the third slot segment 2223 is an arc segment.

[0317] Among them, the bottom wall of the first groove section 2221, the bottom wall of the second groove section 2222 and the bottom wall of the third groove section 2223 all form a first weak section 2211, that is, the first weak portion 221 includes three first weak sections 2211, and the three first weak sections 2211 are respectively the bottom wall of the first groove section 2221, the bottom wall of the second groove section 2222 and the bottom wall of the third groove section 2223, and the three first weak sections 2211 constitute the first weak portion 221.

[0318] A first weak section 2211 is formed in the area corresponding to the third slot section 2223, and the first weak portion 221 includes three first weak sections 2211. The second slot section 2222 connects the first slot section 2221 and the third slot section 2223. The first weak section 2211 formed in the area corresponding to the second slot section 2222 connects the first weak section 2211 formed in the area corresponding to the first slot section 2221 and the first weak section 2211 formed in the area corresponding to the third slot section 2223. When one of the first weak sections 2211 begins to rupture, it can drive the rupture of another first weak section 2211, which is conducive to the rapid rupture of the first weak portion 221 to open the predetermined pressure relief area P and achieve rapid pressure relief.

[0319] The first slot segment 2221 and the third slot segment 2223 are arranged opposite to each other, that is, the first slot segment 2221 and the third slot segment 2223 are spaced apart. For example, in FIG17 , the first slot segment 2221 and the third slot segment 2223 are spaced apart along the length direction Y of the first wall portion, and both the first slot segment 2221 and the third slot segment 2223 extend along the width direction Z of the first wall portion.

[0320] The second slot section 2222 connects the first slot section 2221 and the third slot section 2223. That is, the second slot section 2222 is located between the first slot section 2221 and the third slot section 2223, and the two ends of the second slot section 2222 are respectively connected to the first slot section 2221 and the third slot section 2223. For example, in FIG17 , the second slot section 2222 extends along the longitudinal direction Y of the wall portion. Of course, in other embodiments, the second slot section 2222 may also extend from the first slot section 2221 and the third slot section 2223 at its two ends in the longitudinal direction Y of the wall portion.

[0321] The first groove 222 is provided with a first groove section 2221 and a third groove section 2223 which are arranged opposite to each other, and a second groove section 2222 connecting the first groove section 2221 and the third groove section 2223, so that the pressure relief component 22 can split along the first groove section 2221, the second groove section 2222 and the third groove section 2223 when the battery cell 20 releases pressure, so as to open the predetermined pressure relief area P to release the internal pressure of the battery cell 20. The first groove 222 with such a structure makes the intersection position of the first groove section 2221 and the second groove section 2222 and the intersection position of the second groove section 2222 and the third groove section 2223 weaker, easier to split and open the predetermined pressure relief area P for pressure relief, and can further improve the pressure relief area and pressure relief rate of the battery cell 20.

[0322] As shown in Figure 17, in some embodiments, the position where the second slot segment 2222 is connected to the first slot segment 2221 deviates from the two ends of the first slot segment 2221, and the position where the second slot segment 2222 is connected to the third slot segment 2223 deviates from the two ends of the third slot segment 2223.

[0323] The position where the second slot segment 2222 connects to the first slot segment 2221 deviates from the two ends of the extending direction of the first slot segment 2221. The position where the second slot segment 2222 connects to the third slot segment 2223 deviates from the two ends of the extending direction of the third slot segment 2223.

[0324] Among them, the connection position of the first slot segment 2221 and the second slot segment 2222 deviates from the two ends of the first slot segment 2221, that is, the second slot segment 2222 is connected between the two ends of the first slot segment 2221. Similarly, the connection position of the third slot segment 2223 and the second slot segment 2222 deviates from the two ends of the third slot segment 2223, that is, the second slot segment 2222 is connected between the two ends of the third slot segment 2223, so that the shape of the first groove 222 formed by the first slot segment 2221, the second slot segment 2222 and the third slot segment 2223 is an approximately "H"-shaped structure, and predetermined pressure relief areas P are formed on both sides of the second slot segment 2222. Of course, the areas of the two predetermined pressure relief areas P may be the same or different.

[0325] Exemplarily, the second slot segment 2222 is a straight structure extending along the length direction Y of the first wall portion, the first slot segment 2221 and the third slot segment 2223 are both straight structures extending along the width direction Z of the first wall portion, and the second slot segment 2222 is located between the first slot segment 2221 and the third slot segment 2223 along the length direction Y of the first wall portion.

[0326] By setting the first groove section 2221, the second groove section 2222 and the third groove section 2223 to extend along a straight line, and setting the first groove section 2221 and the third groove section 2223 to be perpendicular to the second groove section 2222, so that the extension direction of the second groove section 2222 is the arrangement direction of the first groove section 2221 and the third groove section 2223, on the one hand, the regularity of the shape of the first groove 222 can be improved, which is conducive to reducing the processing difficulty of the first groove 222, thereby reducing the manufacturing cost of the battery cell 20. On the other hand, the two predetermined pressure relief areas P located on both sides of the second groove section 2222 relieve pressure in opposite directions when the battery cell 20 is depressurized.

[0327] The position where the second groove section 2222 is connected to the first groove section 2221 deviates from the two ends of the first groove section 2221, so the connection position of the first groove section 2221 and the second groove section 2222 is set to be located between the two ends of the first groove section 2221, and the position where the second groove section 2222 is connected to the third groove section 2223 deviates from the two ends of the third groove section 2223, so the connection position of the third groove section 2223 and the second groove section 2222 is set to be located between the two ends of the third groove section 2223. The first groove section 2221, the second groove section 2222 and the third groove section 2223 form an "H"-shaped structure, so that both sides of the second groove section 2222 of the first groove 222 can form a predetermined pressure relief area P, and the two predetermined pressure relief areas P can be opened in a split manner for pressure relief when the battery cell 20 is pressure-relieved, 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.

[0328] The first groove 222 can also be other structures. Referring to Figure 9, the shape of the first groove 222 formed by the first groove section 2221, the second groove section 2222 and the third groove section 2223 can be a "U"-shaped structure, that is, one end of the second groove section 2222 is connected to one end of the first groove section 2221, and the other end is connected to one end of the third groove section 2223, so as to form a predetermined pressure relief area P on the pressure relief component 22.

[0329] In some embodiments, the first groove 222 further includes a fourth groove section 2224 , which is disposed between the first groove section 2221 and the third groove section 2223 . The fourth groove section 2224 is connected to the third groove section 2223 , and a first weak section 2211 is formed in the corresponding area of ​​the fourth groove section 2224 .

[0330] For example, as shown in FIG17 , the fourth slot segment 2224 intersects the second slot segment 2222 at right angles. The fourth slot segment 2224 extends along the width direction Z of the first wall portion. Along the width direction Z of the first wall portion, the length of the fourth slot segment 2224 is less than the length of the first slot segment 2221, and the length of the fourth slot segment 2224 is less than the length of the third slot segment 2223.

[0331] The bottom wall of the fourth trough section 2224 forms a first weak section 2211. The bottom walls of the first trough section 2221, the second trough section 2222, the third trough section 2223 and the fourth trough section 2224 together form a first weak portion 221 including four first weak sections 2211.

[0332] The fourth slot section 2224 is provided to facilitate the pressure relief component 22 to split from the intersection of the second slot section 2222 and the fourth slot section 2224, so that the two predetermined pressure relief areas P on both sides of the second slot section 2222 can be opened synchronously, thereby improving the pressure relief rate.

[0333] As shown in Figure 17, in some embodiments, the first weak portion 221 defines two predetermined pressure relief areas P, and the two predetermined pressure relief areas P are respectively located on both sides of the second groove section 2222; the pressure relief component 22 also includes a second weak portion 228, and the second weak portion 228 is configured to guide the predetermined pressure relief area P to open when the first weak portion 221 is broken, and at least one second weak portion 228 is correspondingly provided for each predetermined pressure relief area P.

[0334] Each predetermined pressure relief area P may be provided with one corresponding second weak portion 228 , or may be provided with multiple corresponding second weak portions 228 .

[0335] Each second weak portion 228 is configured to guide the corresponding predetermined pressure relief area P to flip when the first weak portion 221 is broken, thereby guiding the predetermined pressure relief area P to open.

[0336] The second weak portion 228 can guide the corresponding predetermined pressure relief area P to open. At least one second weak portion 228 is correspondingly provided for each predetermined pressure relief area P, thereby improving the opening effect of each predetermined pressure relief area P 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 P 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, connection failure, etc. caused by untimely pressure relief of the battery cell 20, and is beneficial to improving the reliability of the battery cell 20.

[0337] In some embodiments, a second weak portion 228 is correspondingly provided for each predetermined pressure relief area P; the pressure relief component 22 is provided with a second groove 225 , and the pressure relief component 22 forms a second weak portion 228 in the area where the second groove 225 is provided, and the first groove 222 is located between the two second grooves 225 .

[0338] The first weak portion 221 defines two predetermined pressure relief areas P. Each predetermined pressure relief area P is correspondingly provided with a second weak portion 228 , and two second grooves 225 are provided on the pressure relief component 22 .

[0339] The second groove 225 extends in a direction parallel to the direction of extension of the second groove section 2222 of the first groove 222. The two second grooves 225 are spaced apart along the extending direction of the first groove section 2221 of the first groove 222. The first groove section 2221 and the third groove section 2223 of the first groove 222 are located between the two second grooves 225, and the second groove section 2222 is located between the two second grooves 225, so that the first groove 222 is located between the two second grooves 225.

[0340] Each first groove 222 is located between the edge of the first wall 211 and the first groove 222 along the width direction Z of the first wall. The two first grooves 222 separate the edge of the first wall 211 from the first groove 222 on both sides of the first groove 222 along the width direction Z of the first wall.

[0341] The first groove 222 is located between the two second grooves 225, so that the second groove 225 can also play a certain buffering role on the first groove 222, so that when the battery cell 20 is subjected to internal and external impact forces and deformed, the deformation energy of the battery cell 20 can be absorbed by the second groove 225, so as to play a certain protective role for the area where the first groove 222 of the pressure relief component is provided, thereby effectively reducing the deformation or damage of the area where the first groove 222 of the pressure relief component is provided 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.

[0342] In some embodiments, the second slot segment 2222 is disposed opposite to the second groove 225 along the first direction. Along the first direction, the first slot segment 2221 and the third slot segment 2223 are both spaced apart from the second groove 225 .

[0343] The second groove section 2222 and the second groove 225 are arranged opposite to each other along the first direction, and along the first direction, the first groove section 2221 and the third groove section 2223 are spaced apart from the second groove 225, so the first groove section 2221, the second groove section 2222 and the third groove section 2223 are not in contact with the second groove 225, which can reduce the mutual influence between the first groove 222 and the second groove 225 during the processing, and reduce the phenomenon that the first weak part 221 causes the second weak part 228 to crack when it cracks to release pressure, and can reduce the stress influence between the first weak part 221 and the second weak part 228.

[0344] In some embodiments, the first wall portion 211 is a rectangular structure, and the first direction is parallel to the width direction Z of the first wall portion.

[0345] That is, the first groove section 2221 and the third groove section 2223 extend along the width direction Z of the first wall, and the second groove 225 and the second groove section 2222 extend along the length direction Y of the first wall. The second groove 225 and the second groove section 2222 are arranged opposite to each other along the width direction Z of the first wall.

[0346] The first direction is parallel to the width direction Z of the first wall portion, and the second groove section 2222 and the second groove 225 are arranged opposite to each other along the width direction Z of the first wall portion. Along the width direction Z of the first wall portion, the first groove section 2221 and the third groove section 2223 are spaced apart from the second groove 225. The first groove section 2221, the second groove section 2222 and the third groove section 2223 are not in contact with the second groove 225 in the width direction Z of the first wall portion. This can reduce the mutual influence between the first groove 222 and the second groove 225 during the processing, and can reduce the phenomenon that the second weak portion 228 is cracked when the first weak portion 221 cracks and releases pressure, and can reduce the stress influence between the first weak portion 221 and the second weak portion 228.

[0347] In some embodiments, referring to FIG. 10 , the pressure relief component 22 is integrally formed with the first wall portion 211 .

[0348] That is to say, the pressure relief component 22 and the first wall portion 211 are an integrated structure, and the pressure relief component 22 and the first weak portion 221 are arranged on the first wall portion 211 using an integrated molding process, that is, the pressure relief component 22 is the first wall portion 211, so that the pressure relief component 22 is a part of the outer shell 21.

[0349] For example, in Figure 10 , the first wall portion 211 is the bottom wall of the housing 212, disposed opposite the end cap 213 in the thickness direction X of the first wall portion. The pressure relief component 22 is then the bottom wall, and the first groove 222 forming the first weakened portion 221 is disposed on the bottom wall. If the first 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.

[0350] By setting the pressure relief component 22 and the first wall portion 211 as an integrally formed structure, the pressure relief component 22 is a structure integrated on the first wall portion 211, that is, the pressure relief component 22 is a wall of the outer shell 21, and correspondingly, the pressure relief component 22 is provided on the first wall portion 211. The battery cell 20 adopting this structure can improve the structural strength of the pressure relief component 22 provided on the first wall portion 211, and can reduce the risk of leakage between the pressure relief component 22 and the first wall portion 211 due to improper assembly.

[0351] In some embodiments, the pressure relief component 22 is made of aluminum alloy.

[0352] It is understood that in embodiments where the pressure relief component 22 and the first wall portion 211 are integrally formed, the material of the first wall portion 211 includes an aluminum alloy. If the first wall portion 211 is an end cap 213, the end cap 213 may be made of an aluminum alloy; if the first wall portion 211 is a wall portion within the housing 212, the housing 212 may also be made of an aluminum alloy.

[0353] Aluminum alloy is lightweight and ductile, making it easier to form the first groove 222 on the pressure relief component 22. In the embodiment where the pressure relief component 22 and the first wall portion 211 are integrally formed, the first wall portion 211 is made of aluminum alloy, which can effectively reduce the difficulty of forming the first wall portion 211.

[0354] 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%.

[0355] This aluminum alloy belongs to the third series aluminum, has lower hardness and better forming ability, reduces the processing difficulty of the first groove 61 and the second groove 62, is conducive to improving the processing accuracy of the first groove 61 and the second groove 62, and improves the pressure relief consistency of the pressure relief component 6.

[0356] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 96.7%, 0.05% ≤ copper ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other individual element components ≤ 0.05%, and the total composition of other elements ≤ 0.15%.

[0357] This aluminum alloy belongs to the fifth series aluminum. The pressure relief component 22 made of this aluminum alloy has higher hardness, greater strength and good anti-destruction ability.

[0358] As shown in FIG4 , in some embodiments, the pressure relief component 22 is provided separately from the first wall portion 211 . The first wall portion 211 is provided with a pressure relief hole. The pressure relief component 22 is installed on the wall portion and covers the pressure relief hole.

[0359] The pressure relief hole passes through both sides of the first wall portion in the thickness direction X, and the pressure relief hole is communicated with the interior of the housing 21 .

[0360] The pressure relief component 22 and the first wall portion 211 are provided separately. This means that before the pressure relief component 22 and the first wall portion 211 are assembled, the pressure relief component 22 and the first wall portion 211 are two separate components. To complete the assembly of the pressure relief component 22 and the first wall portion 211, the pressure relief component 22 and the first wall portion 211 need to be connected to form a whole. The pressure relief component 22 can be connected to the hole wall of the pressure relief hole and cover the pressure relief hole. For example, the pressure relief component 22 is welded to the first wall portion 211.

[0361] By arranging the pressure relief component 22 and the first wall portion 211 as a separate structure, the pressure relief component 22 is a structure installed on the first wall portion 211. The battery cell 20 adopting this structure can reduce the difficulty of setting the pressure relief component 22 on the first 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.

[0362] In some embodiments, the battery cell 20 includes an electrode assembly 23 . The electrode assembly 23 is accommodated in the housing 21 , and the first wall portion 211 supports the electrode assembly 23 .

[0363] The battery cell 20 may include one or more electrode assemblies 23. In an embodiment where the battery cell 20 includes a plurality of electrode assemblies 23, the plurality of electrode assemblies 23 are stacked along a thickness direction thereof.

[0364] The first wall portion 211 supports the electrode assembly 23 . It can be understood that the first wall portion 211 bears the weight of the electrode assembly 23 .

[0365] The first wall portion 211 supports the electrode assembly 23 , and the pressure relief component 22 is disposed on the first wall portion 211 , which can reduce the risk of substances released when the battery cell 20 releases pressure acting on other electrical connection structures, thereby reducing the risk of causing other reliability issues.

[0366] In some embodiments, the battery cell 20 includes an electrode terminal 24 , which is disposed on other walls of the housing 21 except the first wall 211 .

[0367] The electrode terminal 24 is provided on other walls of the housing 21 except the first wall portion 211 . That is, the electrode terminal 24 and the pressure relief member 22 are provided on different walls of the housing 21 .

[0368] The electrode terminal 24 is arranged on other walls of the shell 21 except the first wall portion 211, so the risk of the substance discharged from the battery cell 20 when the pressure is released acts on the electrode terminal 24 is low, which can reduce the risk of the battery cell 20 short-circuiting due to the substance discharged from the battery cell 20 when the pressure is released and the electrode terminal 24 forming an electrical connection, causing the battery cell 20 to short-circuit and cause thermal runaway of the battery cell 20 again.

[0369] In some embodiments, the electrode terminal 24 is disposed on a wall portion of the housing 21 opposite to the first wall portion 211 .

[0370] Exemplarily, the housing 212 of the outer shell 21 has a bottom wall opposite to the opening 2121. The end cap 213 covers the opening 2121 and is disposed opposite the bottom wall. The bottom wall is the first wall portion 211, and the electrode terminal 24 is disposed on the end cap 213 covering the opening 2121.

[0371] The electrode terminal 24 is arranged on the wall of the shell 21 opposite to the first wall 211, so that the distance between the electrode terminal 24 and the pressure relief component 22 is farther, which can further reduce the risk of the discharged substance of the battery cell 20 acting on the electrode terminal 24 when the pressure is released, and further reduce the risk of the battery cell 20 short-circuiting due to the formation of electrical connection between the discharged substance and the electrode terminal 24 when the pressure is released, causing the battery cell 20 to short-circuit again and cause thermal runaway of the battery cell 20.

[0372] In some embodiments, the housing 21 includes a shell 212 and an end cover 213 , the shell 212 has at least one opening 2121 ; the end cover 213 corresponds one-to-one to the opening 2121 , the end cover 213 is connected to the shell 212 and closes the opening 2121 ; wherein at least one end cover 213 is the first wall portion 211 .

[0373] The end cap 213 is the first wall portion 211, that is, the pressure relief component 22 is disposed on the end cap 213. In an embodiment where the housing 212 has two opposing openings 2121, the housing 21 includes two end caps 213. One of the two end caps 213 can be the first wall, that is, one end cap 213 is provided with the pressure relief component 22, or both end caps 213 can be the first wall, that is, both end caps 213 are provided with the pressure relief component 22.

[0374] By setting the first 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 with 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.

[0375] It should be noted that the structure of the battery cell 20 is not limited to this. In some embodiments, the battery cell 20 can also have other structures. For example, 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, which is used to accommodate the electrode assembly 23. The end cover 213 closes the opening 2121, and the shell 212 includes a first wall portion 211.

[0376] The shell 212 may include 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.

[0377] The housing 212 includes a first wall portion 211. That is, the first wall portion 211 is a wall of the housing 212. For example, in FIG10 , the first wall portion 211 is a bottom wall of the housing 212 disposed opposite the end cap 213 in the thickness direction X of the first wall portion. Of course, in other embodiments, the first wall portion 211 may also be a side wall of the housing 212.

[0378] By setting the first 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 predetermined pressure relief area P and the first weak portion 221 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.

[0379] It should be noted that the structure of the battery cell 20 can be various. In some embodiments, the shell 212 has two openings 2121 arranged opposite to each other; the outer shell 21 includes two end covers 213, each end cover 213 is connected to the shell 212 and closes an opening 2121, and the shell 212 includes a first wall portion 211.

[0380] The housing 212 defines an interior housing cavity, and both openings 2121 communicate with the housing cavity. The two openings 2121 may be arranged relative to each other along the thickness direction X of the first wall portion. In an embodiment where the housing 21 includes two openings 2121 and two end caps 213 , the first wall portion 211 may also be a wall of the housing 212 .

[0381] The shell 212 of the outer casing 21 has two openings 2121 arranged opposite each other, and the two end caps 213 respectively seal the two openings 2121. This structure of the battery cell 20 facilitates assembly of the battery cell 20 from both ends of the shell 212, thereby reducing the difficulty in manufacturing and assembling the battery cell 20. The shell 212 includes a first wall portion 211, and the pressure relief component 22 is not provided on the end cap 213. This can reduce the risk of substances released from the battery cell 20 during pressure relief from the battery cell 20 interacting with other structures of the battery 100. This further reduces the risk of substances released from the battery cell 20 during pressure relief from the battery cell 20 interacting with the electrode terminals 24 to form an electrical connection, thereby causing a short circuit in the battery cell 20 and further leading to thermal runaway of the battery cell 20.

[0382] In the embodiment where the housing 21 includes two openings 2121 and two end covers 213, the two end covers 213 respectively close the two openings 2121, and one of the two end covers 213 is a first wall portion 211. Of course, both end covers 213 may be first wall portions 211, and each first wall portion 211 may be provided with a pressure relief component 22.

[0383] In some embodiments, the housing 212 has an opening 2121 , and a wall portion of the housing 212 opposite to the opening 2121 is the first wall portion 211 .

[0384] Illustratively, the wall of the housing 212 opposite to the opening 2121 is the bottom wall of the housing 212 , the bottom wall is the first wall 211 , the end cover 213 is disposed opposite to the first wall 211 , and the electrode terminal 24 is disposed on the end cover 213 .

[0385] The wall portion of the shell 212 that is arranged opposite to the opening 2121 is the first wall portion 211, which can reduce the risk of the substance discharged from the battery cell 20 when the pressure is released to act on other structures of the battery 100, thereby further reducing the risk of the battery cell 20 short-circuiting due to the substance discharged from the battery cell 20 when the pressure is released to form an electrical connection with the electrode terminal 24, causing the battery cell 20 to short-circuit and cause thermal runaway of the battery cell 20 again.

[0386] In some embodiments, the pressure relief component 22 is made of steel.

[0387] The steel material can be carbon steel, alloy steel, stainless steel, etc.

[0388] It is understood that in the embodiment where the pressure relief component 22 and the first wall portion 211 are integrally formed, the material of the first wall portion 211 includes steel. If the first wall portion 211 is an end cap 213, the end cap 213 can be made of steel; if the first wall portion 211 is a wall portion in the housing 212, the housing 212 can be made of steel.

[0389] In this embodiment, steel has the characteristic of high strength, and the pressure relief component 22 made of steel has greater strength. Under the condition of a constant burst pressure of the battery cell 20, the pressure relief component 22 can be made thinner, thereby reducing the volume of the pressure relief component 22. In the embodiment where the pressure relief component 22 is integrally formed with the first wall portion 211, the first wall portion 211 is made of steel and can be made thinner. Under the condition of a constant volume of the outer shell 21, the volume of the outer shell 21 can be increased to provide more space for the electrode assembly 23, which is conducive to improving the volumetric energy density of the battery cell 20.

[0390] In some embodiments, the steel material is carbon steel or stainless steel.

[0391] Carbon steel can be low carbon steel, medium carbon steel or high carbon steel.

[0392] In some embodiments, the pressure relief component 22 is made of aluminum alloy.

[0393] It is understood that in embodiments where the pressure relief component 22 and the first wall portion 211 are integrally formed, the material of the first wall portion 211 includes an aluminum alloy. If the first wall portion 211 is an end cap 213, the end cap 213 may be made of an aluminum alloy; if the first wall portion 211 is a wall portion within the housing 212, the housing 212 may also be made of an aluminum alloy.

[0394] Aluminum alloys are lightweight and ductile, making it easier to machine the first and second grooves 222 and 225 in the pressure relief component 22. In embodiments where the pressure relief component 22 and the first wall portion 211 are integrally formed, the aluminum alloy of the first wall portion 211 effectively reduces the difficulty of forming the first wall portion 211. The excellent ductility of aluminum alloys makes it easier to deposit material within the predetermined pressure relief area P when forming the first groove 222.

[0395] In some embodiments, the present application further provides a battery 100 , which includes the battery cell 20 provided in any of the above embodiments.

[0396] As shown in FIG. 2 , the battery 100 may further include a box body 10 , in which the battery cells 20 are accommodated.

[0397] 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 .

[0398] 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.

[0399] 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.

[0400] Optionally, the number of battery cells 20 disposed in 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 in the housing 10. Alternatively, the battery 100 may be a module formed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid configuration, and then the multiple battery modules 100 are then connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed in the housing 10.

[0401] 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 .

[0402] 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 of an electrical device, 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 or longitudinal beam of the vehicle 1000.

[0403] In some embodiments, the present application further provides an electrical device, which includes the battery cell 20 provided in any of the above embodiments.

[0404] The battery cell 20 is used to provide power to an electrical device, wherein the electrical device can be any of the aforementioned devices or systems using the battery cell 20 .

[0405] 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 first 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 serves as the first wall portion 211. The pressure relief component 22 is a separate structure from the first wall portion 211, and is disposed on the first wall portion 211.

[0406] Along the thickness direction X of the first wall portion, the pressure relief component 22 has a first surface 223 and a second surface 224 disposed opposite each other. The first surface 223 is located on the side of the pressure relief component 22 facing away from the interior of the housing 21, and the second surface 224 is located on the side of the pressure relief component 22 facing the interior of the housing 21. The first surface 223 of the pressure relief component 22 is provided with three levels of scored grooves, arranged sequentially from the first surface 223 to the second surface 224. The first level of the scored grooves, the one farthest from the first surface 223, is the first groove 222. The area corresponding to the first groove 222 forms a first weakened portion 221. The first weakened portion 221 defines at least one predetermined pressure relief area P. The pressure relief component 22 is configured to rupture along at least a portion of the first weakened portion 221 when pressure is released from the battery cell 20. The first weakened portion 221 includes a plurality of first weakened segments 2211. The second surface 224 is provided with a second groove 225, and the pressure relief component 22 forms a second weak portion 228 in the area corresponding to the second groove 225. Along the thickness direction X of the first wall portion, the thickness of the second weak portion 228 is greater than the thickness of the first weak portion 221. The second weak portion 228 is configured to guide the predetermined pressure relief area P to flip when the first weak portion 221 is cracked, so as to release the internal pressure of the battery cell 20.

[0407] The first groove 222 includes a first groove section 2221, a second groove section 2222, a third groove section 2223, and a fourth groove section 2224. The first groove section 2221, the second groove section 2222, the third groove section 2223, and the fourth groove section 2224 each form a first weak section 2211. The first groove section 2221 and the third groove section 2223 are spaced apart from each other along the length direction Y of the first wall portion. The first groove section 2221 and the third groove section 2223 both extend in a straight line along the width direction Z of the first wall portion. The third groove section 2223 extends in a straight line along the length direction Y of the first wall portion. The second groove section 2222 connects the first groove section 2221 and the third groove section 2223. The connection between the second groove section 2222 and the first groove section 2221 is located between the two ends of the first groove section 2221, and the connection between the second groove section 2222 and the third groove section 2223 is located between the two ends of the third groove section 2223. The first, second, and third groove sections 2221, 2222, and 2223 form an H-shaped first groove 222. Along the width direction Z of the first wall portion, a predetermined pressure relief zone P is formed on either side of the second groove section 2222. The first weakened portion 221 defines two predetermined pressure relief zones P. The fourth groove section 2224 is located between the first and third groove sections 2221, 2223, and intersects with the second groove section 2222.

[0408] Along the width direction Z of the first wall portion, the dimension of the first wall portion 211 is W. The first weak portion 221 includes at least one first weak section 2211. The cross-sectional area of ​​the first weak section 2211 perpendicular to its extension direction is S1, satisfying 10 mm ≤ W ≤ 100 mm, 0.006 mm² ≤ S1 ≤ 0.15 mm²; preferably, 20 mm ≤ W ≤ 80 mm, 0.01 mm² ≤ S1 ≤ 0.1 mm². The width of the bottom surface of the groove section is A, and the thickness of the first weak section 2211 is H, satisfying the following: S1 = A × H; 0.05 mm ≤ A ≤ 0.5 mm, 0.05 mm ≤ H ≤ 0.6 mm; preferably, 0.1 mm ≤ A ≤ 0.3 mm, 0.08 mm ≤ H ≤ 0.4 mm.

[0409] According to some embodiments of the present application, as shown in Figures 3 and 4, 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 first 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 first wall portion, is the first wall portion 211. The pressure relief component 22 and the first wall portion 211 are integrally formed, that is, the pressure relief component 22 is the first wall portion 211 of the housing 21.

[0410] Along the thickness direction X of the first wall portion, the pressure relief component 22 has a first surface 223 and a second surface 224 disposed opposite each other. The first surface 223 is located on the side of the pressure relief component 22 facing away from the interior of the housing 21, and the second surface 224 is located on the side of the pressure relief component 22 facing the interior of the housing 21. The first surface 223 of the pressure relief component 22 is provided with three levels of scored grooves, arranged sequentially from the first surface 223 to the second surface 224. The first level of the scored grooves, the one farthest from the first surface 223, is the first groove 222. The area corresponding to the first groove 222 forms a first weakened portion 221. The first weakened portion 221 defines at least one predetermined pressure relief area P. The pressure relief component 22 is configured to rupture along at least a portion of the first weakened portion 221 when pressure is released from the battery cell 20. The first weakened portion 221 includes a plurality of first weakened segments 2211. The second surface 224 is provided with a second groove 225, and the pressure relief component 22 forms a second weak portion 228 in the area corresponding to the second groove 225. Along the thickness direction X of the first wall portion, the thickness of the second weak portion 228 is greater than the thickness of the first weak portion 221. The second weak portion 228 is configured to guide the predetermined pressure relief area P to flip when the first weak portion 221 is cracked, so as to release the internal pressure of the battery cell 20.

[0411] The first groove 222 includes a first groove section 2221, a second groove section 2222, a third groove section 2223, and a fourth groove section 2224. The first groove section 2221, the second groove section 2222, the third groove section 2223, and the fourth groove section 2224 each form a first weak section 2211. The first groove section 2221 and the third groove section 2223 are spaced apart from each other along the length direction Y of the first wall portion. The first groove section 2221 and the third groove section 2223 both extend in a straight line along the width direction Z of the first wall portion. The third groove section 2223 extends in a straight line along the length direction Y of the first wall portion. The second groove section 2222 connects the first groove section 2221 and the third groove section 2223. The connection between the second groove section 2222 and the first groove section 2221 is located between the two ends of the first groove section 2221, and the connection between the second groove section 2222 and the third groove section 2223 is located between the two ends of the third groove section 2223. The first, second, and third groove sections 2221, 2222, and 2223 form an H-shaped first groove 222. Along the width direction Z of the first wall portion, a predetermined pressure relief zone P is formed on either side of the second groove section 2222. The first weakened portion 221 defines two predetermined pressure relief zones P. The fourth groove section 2224 is located between the first and third groove sections 2221, 2223, and intersects with the second groove section 2222.

[0412] Along the width direction Z of the first wall portion, the dimension of the first wall portion 211 is W. The first weak portion 221 includes at least one first weak section 2211. The cross-sectional area of ​​the first weak section 2211 perpendicular to its extension direction is S1, satisfying 10 mm ≤ W ≤ 100 mm, 0.006 mm² ≤ S1 ≤ 0.15 mm²; preferably, 20 mm ≤ W ≤ 80 mm, 0.01 mm² ≤ S1 ≤ 0.1 mm². The width of the bottom surface of the first groove 222 is A, and the thickness of the first weak section 2211 is H, satisfying the following: S1 = A × H; 0.05 mm ≤ A ≤ 0.5 mm, 0.05 mm ≤ H ≤ 0.6 mm; preferably, 0.1 mm ≤ A ≤ 0.3 mm, 0.08 mm ≤ H ≤ 0.4 mm.

[0413] 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 including a first wall portion; A pressure relief component disposed on the first wall portion, the pressure relief component including a first weak portion that defines at least one predetermined pressure relief area, and the pressure relief component being configured to crack along at least part of the first weak portion when the battery cell relieves pressure; Wherein, along the width direction of the first wall portion, the size of the first wall portion is W, the first weak portion includes at least one first weak segment, and the cross-sectional area of the first weak segment perpendicular to its extending direction is S1, satisfying: 10 mm ≤ W ≤ 100 mm, 0.006 mm 2 ≤ S1 ≤ 0.15 mm 2 .

2. The battery cell according to claim 1, wherein 20mm ≤ W ≤ 80mm; 0.01mm 2 ≤ S1 ≤ 0.1mm2.

3. The battery cell according to any one of claims 1-2, wherein, The pressure relief component is provided with a first groove, the first groove includes at least one groove section, and the pressure relief component forms at least one first weak section in the area where the groove section is provided. The width of the groove bottom surface of the groove section is A in mm, and the thickness of the first weak section is H in mm, satisfying that the area S1 of the cross-section of the first weak section perpendicular to its extending direction is the product of the width A of the groove bottom surface of the groove section and the thickness H of the first weak section; 0.1 mm ≤ A ≤ 0.3 mm, 0.06 mm ≤ H ≤ 0.5 mm; optionally, 0.15 mm ≤ A ≤ 0.25 mm, 0.1 mm ≤ H ≤ 0.3 mm.

4. The battery cell according to claim 3, wherein, The pressure relief component has a first surface and a second surface that are oppositely arranged in the thickness direction of the first wall portion. The first groove is a multi-stage notch groove, and the multi-stage notch grooves are sequentially arranged along the direction from the first surface to the second surface. Among two adjacent stages of the notch grooves, the notch groove of the stage farther from the first surface is disposed on the groove bottom surface of the notch groove of the stage closer to the first surface.

5. The battery cell according to claim 4, wherein, The first groove includes three stages of notch grooves, and the three stages of notch grooves are sequentially arranged along the direction from the first surface to the second surface.

6. The battery cell according to any one of claims 1-5, wherein, The pressure relief component further includes a second weak portion configured to guide the opening of the predetermined pressure relief area.

7. The battery cell according to claim 6, wherein The pressure relief component is provided with a second groove, and the pressure relief component forms the second weak portion in the area where the second groove is provided.

8. The battery cell according to claim 7, wherein, The second groove is disposed on the surface of the pressure relief component facing the interior of the housing.

9. The battery cell according to any one of claims 6-8, wherein, The pressure relief component has a first surface and a second surface that are oppositely arranged in the thickness direction of the first wall portion. The first surface is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided. The second surface is provided with a second groove, and the pressure relief component forms the second weak portion in the area where the second groove is provided.

10. The battery cell according to claim 9, wherein, The first surface is the surface of the pressure relief component facing away from the interior of the housing, and the second surface is the surface of the pressure relief component facing the interior of the housing.

11. The battery cell according to any one of claims 7-10, wherein, Along the thickness direction of the first wall portion, the projection of the first groove does not contact the projection of the second groove.

12. The battery cell according to any one of claims 1-11, wherein, The pressure relief component is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided; The first groove includes a connected first groove section and a second groove section. The pressure relief component forms one first weak section in the area of the first groove section, and the pressure relief component forms one first weak section in the area corresponding to the second groove section.

13. The battery cell according to claim 12, wherein, The first groove includes a third groove section, the first groove section and the third groove section are oppositely arranged, the second groove section connects the first groove section and the third groove section, and the pressure relief component forms a first weak section in the area corresponding to the third groove section.

14. The battery cell according to claim 13, wherein, The position where the second groove section is connected to the first groove section deviates from both ends of the first groove section, and the position where the second groove section is connected to the third groove section deviates from both ends of the third groove section.

15. The battery cell according to claim 13 or 14, wherein, The first weak part defines two predetermined pressure relief areas, and the two predetermined pressure relief areas are respectively located on both sides of the second groove section; The pressure relief component further includes a second weak part, and the second weak part is configured to guide the opening of the predetermined pressure relief area when the first weak part cracks, and at least one second weak part is correspondingly arranged for each predetermined pressure relief area.

16. The battery cell according to claim 15, wherein, One second weak part is correspondingly arranged for each predetermined pressure relief area; The pressure relief component is provided with a second groove, and the pressure relief component forms the second weak part in the area where the second groove is provided, and the first groove is located between the two second grooves.

17. The battery cell according to claim 16, wherein, The second groove section is oppositely arranged to the second groove along a first direction, and along the first direction, both the first groove section and the third groove section are spaced apart from the second groove.

18. The battery cell according to claim 17, wherein, The first wall part is a rectangular structure, and the first direction is parallel to the width direction of the first wall part.

19. The battery cell according to any one of claims 1-18, wherein, The pressure relief component is integrally formed with the first wall part.

20. The battery cell according to any one of claims 1-18, wherein, The pressure relief component is separately arranged from the first wall part, the first wall part is provided with a pressure relief hole, and the pressure relief component is installed on the wall part and covers the pressure relief hole.

21. The battery cell according to any one of claims 1-20, wherein, The battery cell includes an electrode assembly, the electrode assembly is accommodated in the housing, and the first wall part supports the electrode assembly.

22. The battery cell according to any one of claims 1-21, wherein, The battery cell includes electrode terminals, and the electrode terminals are arranged on other wall parts of the housing except the first wall part.

23. The battery cell according to claim 22, wherein The electrode terminals are arranged on the wall part of the housing opposite to the first wall part.

24. The battery cell according to any one of claims 1-23, wherein, The housing includes: A housing body having at least one opening; End caps, corresponding to the openings one by one, the end caps are connected to the housing body and close the openings; Wherein, at least one of the end caps is the first wall part, or the housing body includes the first wall part.

25. The battery cell according to claim 24, wherein, The housing body has two openings arranged oppositely; the housing includes two end caps, each end cap is connected to the housing body and closes one opening, and the housing body includes the first wall part.

26. The battery cell according to claim 24, wherein, The housing body has one opening, and the wall part of the housing body opposite to the opening is the first wall part.

27. The battery cell according to any one of claims 1-26, wherein, The material of the pressure relief component includes steel material.

28. The battery cell according to claim 27, wherein, The steel material is carbon steel or stainless steel.

29. A battery, comprising the battery cell according to any one of claims 1-28.

30. An electrical device, comprising the battery cell according to any one of claims 1-28.

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