Battery cell, battery, and electric device

Abstract

This application provides a battery cell, a battery, and an electrical device, relating to the field of battery technology. The battery cell includes a casing and a pressure relief component; the casing includes a first wall portion; the pressure relief component is disposed on the first wall portion, a first weak point of the pressure relief component defines at least one predetermined pressure relief area, and the pressure relief component is configured to split along at least a portion of the first weak point when the battery cell is depressurized; the sum of the areas of the predetermined pressure relief areas is S, and the first weak point includes at least one first weak segment, the cross-sectional area of ​​the first weak segment perpendicular to its extending direction being S1, 300 mm². 2 ≤S≤1500mm 2 0.006mm 2 ≤S1≤0.15mm 2 This can reduce the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component at the first weak point of the battery cell after long-term use, and can also reduce the risk of the battery cell casing bursting, exploding, or catching fire due to untimely pressure relief by the pressure relief component, thereby effectively improving the reliability of the battery cell.

Description

Technical Field

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

[0002] Batteries are widely used in new energy vehicles, electronic devices, and other fields. As the demand for batteries increases, higher requirements are being placed on their reliability.

[0003] In battery technology, the pressure relief components of a battery cell are one of the most important factors affecting its reliability. These components release internal pressure within the battery cell when the pressure or temperature reaches a threshold. However, after multiple cycles and long-term use, these components are prone to premature pressure release or fatigue cracking, reducing the reliability of the battery cell. Summary of the Invention

[0004] This application provides a battery cell, a battery, and an electrical device to improve the reliability of the battery cell.

[0005] In a first aspect, embodiments of this application provide a battery cell, the battery cell including a casing and a pressure relief component; the casing includes a first wall portion; the pressure relief component is disposed on the first wall portion, the pressure relief component includes a first weak portion, the first weak portion defining at least one predetermined pressure relief area, the pressure relief component is configured to split along at least a portion of the first weak portion when the battery cell is depressurized; wherein, the sum of the areas of all the predetermined pressure relief areas is S, the first weak portion includes at least one first weak segment, the area of ​​the cross-sectional area of ​​the first weak segment perpendicular to its extension direction is S1, satisfying: 300mm 2 ≤S≤1500mm 2 0.006mm 2 ≤S1≤0.15mm 2 .

[0006] In the above technical solution, a pressure relief component is provided on the first wall of the casing. This component includes a first weak point, which can crack when the battery cell is depressurized to release the internal pressure of the battery cell, thereby reducing the risk of explosions or fires caused by excessive internal pressure. The sum of the areas of all predetermined pressure relief zones is greater than or equal to 300 mm². 2This design can alleviate the problem of excessive pressure bearing capacity in the first weakest section of the first weakest part, which leads to excessive burst pressure required by the pressure relief component when depressurizing a battery cell. This reduces the risk of battery cell casing rupture, explosion, or fire due to untimely pressure relief by the pressure relief component, thereby effectively improving the reliability of the battery cell. The sum of the areas of all predetermined pressure relief zones is less than or equal to 1500 mm². 2 This design reduces the stress concentration in the predetermined pressure relief area and the first weakest segment of the first weak part when the expansion force generated by the expansion of the battery cell acts on the pressure relief component during use. It also improves the stress absorption effect of the predetermined pressure relief area, thereby reducing the strain and strain amplitude of the first weakest segment of the pressure relief component. This reduces the risk of premature actuation or fatigue cracking of the battery cell during use, improves the stability of the pressure relief component when the battery cell is in use, and ultimately increases the service life and reliability of the battery cell. The cross-sectional area of ​​the first weakest segment of the first weak part perpendicular to its extension direction is greater than or equal to 0.006 mm². 2 This design reduces the stress concentration in the predetermined pressure relief area and the first weakest segment of the first weak part when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component. It also improves the stress absorption effect of the predetermined pressure relief area, thereby reducing the strain and strain amplitude of the first weakest segment of the pressure relief component. This further reduces the risk of premature actuation or fatigue cracking of the battery cell during use, further improving the stability of the pressure relief component, and ultimately increasing the service life and reliability of the battery cell. The cross-sectional area of ​​the first weakest segment of the first weak part perpendicular to its extension direction is less than or equal to 0.15 mm². 2 This can alleviate the problem of excessive pressure bearing capacity in the first weak section of the first weak part, which causes excessive burst pressure required by the pressure relief component when the battery cell is depressurized. This can reduce the risk of the battery cell casing cracking, exploding, or catching fire due to untimely pressure relief by the pressure relief component, thereby effectively improving the reliability of the battery cell.

[0007] In some embodiments of the first aspect of this application, 400mm 2 ≤S≤1200mm 2 0.01mm 2 ≤S1≤0.1mm 2 .

[0008] In the above technical solution, the sum of the areas of all predetermined pressure relief zones is greater than or equal to 400 mm². 2This design can further alleviate the problem of excessive pressure bearing capacity in the first weakest section of the first weak part, which leads to excessive burst pressure required by the pressure relief component when depressurizing the battery cell. This further reduces the risk of battery cell casing rupture, explosion, or fire due to untimely pressure relief by the pressure relief component, thereby effectively improving the reliability of the battery cell. The sum of the areas of all predetermined pressure relief zones is less than or equal to 1200 mm². 2 This design can further reduce the stress concentration in the predetermined pressure relief area and the first weakest segment of the first weak part when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component. It also further enhances the stress absorption effect of the predetermined pressure relief area, thereby further reducing the strain and strain amplitude of the first weakest segment of the pressure relief component. This further reduces the risk of premature actuation or fatigue cracking of the battery cell during use, further improving the stability of the pressure relief component, and ultimately increasing the service life and reliability of the battery cell. The cross-sectional area of ​​the first weakest segment of the first weak part perpendicular to its extension direction is greater than or equal to 0.01 mm². 2 This design can further reduce the stress concentration in the predetermined pressure relief area and the first weak segment of the first weak part when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component. It also further enhances the stress absorption effect of the predetermined pressure relief area, thereby further reducing the strain and strain amplitude of the first weak part of the pressure relief component. This further reduces the risk of premature actuation or fatigue cracking of the battery cell during use, further improving the stability of the pressure relief component, and ultimately increasing the service life and reliability of the battery cell. The cross-sectional area of ​​the first weak segment of the first weak part perpendicular to its extension direction is less than or equal to 0.1 mm². 2 This can further alleviate the phenomenon that the pressure-bearing capacity of the first weak section of the first weak part is too large, which causes the pressure relief component to require too much burst pressure when the battery cell is depressurized. This can further reduce the risk of the battery cell casing cracking, exploding, or catching fire due to the untimely pressure relief of the pressure relief component, and thus further improve the reliability of the battery cell.

[0009] In some embodiments of the first aspect of this application, the pressure relief component is provided with a first groove, the first groove including at least one groove segment, the pressure relief component forming at least one first weak segment in the area where the groove segment is provided, the width of the bottom surface of the groove segment is A, and the thickness of the first weak segment is H, satisfying: S1=A×H; 0.1mm≤A≤0.3mm; 0.06mm≤H≤0.5mm.

[0010] In the above technical solution, the area S1 of the cross-section of the first weak segment of the first weak part perpendicular to its extension direction is the product of the width A of the bottom surface of the groove segment and the thickness H of the first weak part. The width A of the bottom surface of the groove segment 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 bottom surface of the groove segment 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 segment of the first weak part can be reduced, and the stress absorption effect of the predetermined pressure relief area can be improved. This can further reduce the strain and strain amplitude of the first weak part of the pressure relief component, and further reduce the risk of premature actuation or fatigue cracking of the pressure relief component during the 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 part to less than or equal to 0.5 mm, the burst pressure required by the pressure relief component during pressure relief can be reduced, thereby further reducing the risk of the battery cell casing bursting, exploding, or catching fire due to untimely pressure relief by the pressure relief component.

[0011] In some embodiments of the first aspect of this application, 0.15mm≤A≤0.25mm, 0.1mm≤H≤0.3mm.

[0012] In the above technical solution, by setting the width A of the bottom surface of the groove segment to be greater than or equal to 0.15 mm and the thickness H of the first weak part to be greater than or equal to 0.1 mm, the concentration of stress in the first weak section of the first weak part caused by the expansion of the battery cell can be further reduced, and the stress absorption effect of the predetermined pressure relief zone can be further improved. This can further reduce the strain and strain amplitude of the first weak part of the pressure relief component, thereby further reducing the risk of premature actuation or fatigue cracking of the pressure relief component during the use of the battery cell. By setting the width A of the bottom surface of the groove segment to be less than or equal to 0.25 mm and the thickness H of the first weak part to be less than or equal to 0.3 mm, the burst pressure required for the pressure relief component during pressure relief can be further reduced, thereby further reducing the risk of the battery cell casing bursting, exploding, or catching fire due to untimely pressure relief by the pressure relief component.

[0013] In some embodiments of the first aspect of this application, the pressure relief component has a first surface and a second surface disposed opposite to each other in the thickness direction of the first wall portion, the first groove is a multi-level groove, the multi-level grooves are arranged sequentially along the direction from the first surface to the second surface, and in two adjacent levels of the grooves, the first-level groove away from the first surface is disposed on the bottom surface of the first-level groove close to the first surface.

[0014] In the above technical solution, by setting the first groove as a stepped groove structure along the thickness direction of the first wall, the first groove is formed by multiple processing steps. With this structure, when forming a first weak part of the same thickness, on the one hand, the depth of a single processing step of the scoring groove can be reduced, which helps to reduce the manufacturing difficulty and the demand on manufacturing equipment for forming a first weak part of the same thickness, thereby reducing manufacturing costs. It can also reduce the forming force on the pressure relief component during a single processing step in the formation of the first weak part, which helps to reduce the risk of cracking in the pressure relief component and improve the production quality of the battery cell. On the other hand, it can improve the material flow pattern during the formation of the first weak part, which is conducive to the flow of material generated during the formation of the first weak part, thereby improving the consistency of the structure of the multi-stage scoring groove.

[0015] In some embodiments of the first aspect of this application, the first groove includes three levels of grooves, which are sequentially arranged along the direction from the first surface to the second surface.

[0016] In the above technical solution, the first groove includes a three-level scoring groove. When forming a first weak part of equal thickness, it can reduce the depth of a single processing of the scoring groove, which is beneficial to reducing the manufacturing difficulty and the demand for manufacturing equipment in forming a first weak part of equal thickness, thereby reducing manufacturing costs. It can also reduce the forming force on the pressure relief component during a single processing of the first weak part, which is beneficial to reducing the risk of cracking in the pressure relief component and improving the production quality of the battery cell. On the other hand, it can improve the material flow pattern during the formation of the first weak part, which is beneficial to the flow of material generated during the formation of the first weak part, thereby improving the structural consistency of the multi-level scoring groove. It also alleviates the problem of increased processing time caused by multiple processing required for the formation of the first weak part.

[0017] In some embodiments of the first aspect of this application, the pressure relief component further includes a second weak portion configured to guide the predetermined pressure relief zone to open.

[0018] In the above technical solution, the second weak part can guide the opening of the predetermined pressure relief area, thereby improving the opening effect of the predetermined pressure relief area of ​​the pressure relief component. This is beneficial to increasing the pressure relief area of ​​the battery cell after the predetermined pressure relief area is opened, and thus can increase the pressure relief rate of the battery cell when thermal runaway occurs. This reduces the risk of fire, explosion, connection failure and other problems caused by untimely pressure relief of the battery cell, and helps to improve the reliability of the battery cell.

[0019] In some embodiments of the first aspect of this application, the pressure relief component is provided with a second groove, and the pressure relief component forms a second weak portion in the area where the second groove is provided.

[0020] 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 part in the area corresponding to the second groove. The battery cell with this structure is easy to form a second weak part on the pressure relief component, which helps to reduce the difficulty of forming a second weak part on the pressure relief component and improve the production efficiency of the battery cell.

[0021] In some embodiments of the first aspect of this application, the second groove is disposed on the surface of the pressure relief component facing the interior of the housing.

[0022] In the above technical solution, by setting the second groove on the surface of the pressure relief component facing the inside of the housing, the predetermined pressure relief area can be flipped outward of the housing around the bottom wall of the second groove after being opened. This reduces the interference effect of the side 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.

[0023] In some embodiments of the first aspect of this application, the pressure relief component has a first surface and a second surface disposed 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 a 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 a second weak portion in the area where the second groove is provided.

[0024] In the above technical solution, by setting 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 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, which helps to reduce the mutual influence between the first groove and the second groove during the processing.

[0025] In some embodiments of the first aspect of this application, 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.

[0026] In the above technical solution, by respectively setting 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 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, which helps to reduce the mutual influence between the first groove and the second groove during the processing. Furthermore, setting the second groove on the second surface of the pressure relief component facing the inside of the outer shell allows the predetermined pressure relief area to flip outwards from the bottom wall of the second groove after being opened, thereby reducing the interference effect of the side surface of the second groove on the predetermined pressure relief area during the flipping process and improving the flipping effect of the predetermined pressure relief area.

[0027] In some embodiments of the first aspect of this application, the projection of the first groove and the projection of the second groove do not contact each other along the thickness direction of the first wall portion.

[0028] In the above technical solution, by setting the projection of the first groove in the thickness direction of the first wall and the projection of the second groove in the thickness direction of the first wall to be non-contacting, on the one hand, the mutual influence between the first groove and the second groove during the processing can be reduced, on the other hand, the phenomenon that the second weak part cracks when the first weak part cracks and releases pressure can be reduced, and the stress influence between the first weak part and the second weak part can be reduced.

[0029] In some embodiments of the first aspect of this application, the pressure relief component is provided with a first groove, and the pressure relief component forms a first weak portion in the area where the first groove is provided; the first groove includes a first groove segment and a second groove segment connected together, the pressure relief component forms a first weak segment in the area of ​​the first groove segment, and the pressure relief component forms a first weak segment in the area corresponding to the second groove segment.

[0030] In the above technical solution, the first groove includes a first groove segment and a second groove segment, and the first groove segment and the second groove segment are interconnected. On the one hand, it can increase the pressure relief area of ​​the battery cell to improve the pressure relief rate of the battery cell. On the other hand, it makes the connection between the first groove segment and the second groove segment weaker, making it easier to crack and open the predetermined pressure relief area to release the internal pressure of the battery cell.

[0031] In some embodiments of the first aspect of this application, the first groove includes a third groove segment, the first groove segment and the third groove segment are disposed 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.

[0032] In the above technical solution, the first groove is provided with a first groove segment and a third groove segment arranged opposite to each other, and a second groove segment connecting the first groove segment and the third groove segment, so that the pressure relief component can crack along the first groove segment, the second groove segment and the third groove segment when the battery cell is depressurized, so as to open the predetermined pressure relief area to release the internal pressure of the battery cell. The first groove with this structure makes the intersection of the first groove segment and the second groove segment and the intersection of the second groove segment and the third groove segment weaker, making it easier to crack 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.

[0033] In some embodiments of the first aspect of this application, the position where the second slot segment is connected to the first slot segment is offset from both ends of the first slot segment, and the position where the second slot segment is connected to the third slot segment is offset from both ends of the third slot segment.

[0034] In the above technical solution, the position where the second groove segment is connected to the first groove segment is offset from both ends of the first groove segment. Therefore, the connection position between the first groove segment and the second groove segment is set to be between the two ends of the first groove segment. The position where the second groove segment is connected to the third groove segment is offset from both ends of the third groove segment. Therefore, the connection position between the third groove segment and the second groove segment is set to be 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 both sides of the second groove segment of the first groove can form a predetermined pressure relief area. Moreover, the two predetermined pressure relief areas can be opened in a split manner to relieve pressure when the battery cell is depressurized, which is beneficial to further increase the pressure relief effect of the battery cell and can effectively improve the pressure relief rate of the battery cell.

[0035] In some embodiments of the first aspect of this application, the first weak portion defines two predetermined pressure relief zones, the two predetermined pressure relief zones being located on both sides of the second groove segment; the pressure relief component further includes a second weak portion, the second weak portion being configured to guide the predetermined pressure relief zones to open, and each predetermined pressure relief zone corresponding to at least one second weak portion.

[0036] In the above technical solution, the second weak part can guide the corresponding predetermined pressure relief area to open. Each predetermined pressure relief area is provided with at least one second weak part, which can improve the opening effect of each predetermined pressure relief area of ​​the pressure relief component. This is beneficial to increase the pressure relief area of ​​the battery cell after the predetermined pressure relief area is opened, thereby increasing the pressure relief rate of the battery cell when thermal runaway occurs. This reduces the risk of fire, explosion, connection failure and other problems caused by untimely pressure relief of the battery cell, and helps to improve the reliability of the battery cell.

[0037] In some embodiments of the first aspect of this application, each of the predetermined pressure relief zones is provided with a second weak portion; 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 two second grooves.

[0038] In the above technical solution, the first groove is located between the two second grooves, so that the second grooves can also play a certain buffering role for the first groove. Thus, when the battery cell is subjected to internal and external impact forces and deforms, the second grooves can also absorb the deformation energy of the battery cell, so as to play a certain protection role for the area of ​​the pressure relief component where the first groove is provided. In this way, it can effectively reduce the deformation or damage of the area of ​​the pressure relief component where the first groove is provided when the battery cell is subjected to internal and external impact forces, thereby alleviating the situation of premature pressure relief of the battery cell during use.

[0039] In some embodiments of the first aspect of this application, the second groove segment and the second recess are disposed opposite to each other along a first direction, and along the first direction, both the first groove segment and the third groove segment are spaced apart from the second recess.

[0040] In the above technical solution, the second groove segment and the second groove are arranged opposite to each other along the first direction, and along the first direction, the first groove segment and the third groove segment are spaced apart from the second groove segment. Thus, the first groove segment, the second groove segment and the third groove segment do not contact the second groove segment. This can reduce the mutual influence between the first groove segment and the second groove segment during the processing, reduce the phenomenon that the second weak part will crack when the first weak part cracks and releases pressure, and reduce the stress influence between the first weak part and the second weak part.

[0041] In some embodiments of the first aspect of this application, the first wall portion is a rectangular structure, and the first direction is parallel to the width direction of the first wall portion.

[0042] In the above technical solution, the first direction is parallel to the width direction of the first wall portion. The second groove segment 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 segment and the third groove segment are spaced apart from the second groove. The first groove segment, the second groove segment, and the third groove segment do not contact 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, reduce the phenomenon that the second weak part will crack when the first weak part cracks and releases pressure, and reduce the stress influence between the first weak part and the second weak part.

[0043] In some embodiments of the first aspect of this application, the pressure relief component is integrally formed with the first wall portion.

[0044] In the above technical solution, by setting the pressure relief component and the first wall as an integrally formed structure, the pressure relief component is integrated into the first wall, that is, the pressure relief component is a wall of the shell. Correspondingly, the pressure relief component is provided on the first wall. The battery cell with this structure can improve the structural strength of the pressure relief component on the first wall and reduce the risk of leakage caused by improper assembly between the pressure relief component and the first wall.

[0045] In some embodiments of the first aspect of this application, the pressure relief component is separately disposed 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.

[0046] In the above technical solution, by setting the pressure relief component and the first wall as separate components, the pressure relief component is installed on the first wall. The battery cell with this structure can reduce the difficulty of setting the pressure relief component on the first wall, and can make the processing of the casing and the processing of the pressure relief component can be carried out simultaneously, which is beneficial to optimizing the production cycle of the battery cell.

[0047] In some embodiments of the first aspect of this application, the battery cell includes an electrode assembly housed within the housing, and the first wall supports the electrode assembly.

[0048] In the above technical solution, the first wall supports the electrode assembly, and the pressure relief component is set on the first wall, which can reduce the risk that the substances released when the battery cell is depressurized will act on other electrical connection structures, thereby reducing the risk of causing other reliability problems.

[0049] In some embodiments of the first aspect of this application, the battery cell includes electrode terminals disposed on other walls of the housing besides the first wall portion.

[0050] In the above technical solution, the electrode terminals are located on other walls of the outer casing besides the first wall. This reduces the risk of the substances released when the battery cell is depressurized acting on the electrode terminals. It also reduces the risk of the battery cell short-circuiting again and causing thermal runaway due to the substances released when the battery cell is depressurized acting on the electrode terminals to form an electrical connection.

[0051] In some embodiments of the first aspect of this application, the electrode terminals are disposed on the wall of the housing opposite to the first wall portion.

[0052] In the above technical solution, the electrode terminals are located on the wall of the outer casing opposite to the first wall, which makes the distance between the electrode terminals and the pressure relief component greater. This can further reduce the risk of the substances released when the battery cell is depressurized acting on the electrode terminals, and further reduce the risk of the battery cell short circuit caused by the substances released when the battery cell is depressurized forming an electrical connection with the electrode terminals, which would then cause thermal runaway of the battery cell.

[0053] In some embodiments of the first aspect of this application, the housing includes a shell and an end cap, the shell having at least one opening; the end cap corresponds one-to-one with the opening, the end cap being connected to the shell and closing the opening; wherein at least one of the end caps is the first wall portion, or the shell includes the first wall portion.

[0054] In the above technical solution, by setting the first wall of the outer casing as an end cap for closing the opening, the battery cell with this structure facilitates the installation of pressure relief components on the end cap, which helps reduce the manufacturing difficulty of the battery cell and improves its production efficiency. By setting the first wall of the outer casing as a wall of the housing, the area where the pressure relief component is located on the outer casing is far away from the end cap. This effectively alleviates the stress generated by the connection between the end cap and the housing on the pressure relief component, reducing the impact on the predetermined pressure relief area and the first weak point of the pressure relief component. This, in turn, helps reduce the risk of cracking or structural strength reduction of the pressure relief component under tensile stress, thereby improving the service life and reliability of the battery cell.

[0055] In some embodiments of the first aspect of this application, the housing has two openings arranged opposite to each other; the outer shell includes two end caps, each end cap being connected to the housing and closing one of the openings, and the housing includes the first wall portion.

[0056] In the above technical solution, the outer casing has two openings arranged opposite each other, and the two end caps respectively close the two openings. This structure facilitates the assembly of battery cells from both ends of the casing, reducing the manufacturing and assembly difficulty of the battery cells. The casing includes a first wall portion, and the pressure relief component is not located on the end caps. This reduces the risk of substances released during battery cell pressure relief affecting other battery structures, further reducing the risk of short circuits caused by substances released during battery cell pressure relief forming electrical connections with the electrode terminals, leading to thermal runaway of the battery cell.

[0057] In some embodiments of the first aspect of this application, the housing has one opening, and the wall portion of the housing disposed opposite to the opening is the first wall portion.

[0058] In the above technical solution, the wall portion of the casing opposite to the opening is the first wall portion, which can reduce the risk of the substances released when the battery cell is depressurized acting on other structures of the battery. This further reduces the risk of the battery cell short circuit caused by the substances released when the battery cell is depressurized forming an electrical connection with the electrode terminals, which could then lead to thermal runaway of the battery cell.

[0059] Secondly, embodiments of this application also provide a battery, including the aforementioned battery cell.

[0060] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned battery cell. Attached Figure Description

[0061] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0062] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0063] Figure 2 An exploded view of a battery provided in some embodiments of this application;

[0064] Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0065] Figure 4 An exploded view of a battery cell provided in some embodiments of this application;

[0066] Figure 5 This is a schematic diagram of the structure of a pressure relief component provided in some embodiments of this application;

[0067] Figure 6 Cross-sectional views of pressure relief components provided in some embodiments of this application;

[0068] Figure 7 for Figure 6 Enlarged view at point B1;

[0069] Figure 8 Bottom view of the housing provided for some embodiments of this application;

[0070] Figure 9 Bottom view of the housing provided in some embodiments of this application;

[0071] Figure 10 A schematic diagram of the casing of a battery cell provided in some embodiments of this application;

[0072] Figure 11 Bottom view of the housing provided for other embodiments of this application;

[0073] Figure 12 for Figure 11 A cross-sectional view along the Q1-Q1 direction;

[0074] Figure 13 for Figure 12 Enlarged view at B2;

[0075] Figure 14 for Figure 11 A cross-sectional view along the Q2-Q2 direction;

[0076] Figure 15 for Figure 14 Enlarged view at B3;

[0077] Figure 16 for Figure 14 Enlarged view at B4 in the middle;

[0078] Figure 17 Bottom view of the housing provided for some embodiments of this application;

[0079] Figure 18 for Figure 17 A cross-sectional view along the Q3-Q3 direction;

[0080] Figure 19 for Figure 18 Enlarged view at B5 in the middle;

[0081] Figure 20 for Figure 18 Enlarged view of section B6 in the middle.

[0082] Icons: 1000 - Vehicle; 100 - Battery; 10 - Housing; 11 - First Housing Body; 12 - Second Housing Body; 20 - Battery Cell; 21 - Casing; 211 - First Wall; 212 - Housing; 2121 - Opening; 213 - End Cap; 22 - Pressure Relief Component; 221 - First Weak Point; 2211 - First Weak Section; 2222 - First Groove; 2221 - First Slot Section; 2222 - Second Slot Section; 2223 - Third Slot Section; 2224 - Fourth Slot Section; 223 - First Surface; 224 - Second Surface; 222a - First Sub-slot; 222a1 - First Segment; 222 a2 - Second segment; 222a3 - Third segment; 222b - Second sub-slot; 222b1 - Fourth segment; 222b2 - Fifth segment; 222b3 - Sixth segment; 222c - Third sub-slot; 222c1 - Seventh segment; 222c2 - Eighth segment; 222c3 - Ninth segment; 225 - Second groove; 228 - Second weak part; 23 - Electrode assembly; 231 - Electrode tab; 24 - Electrode terminal; 25 - Current collector; 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 Implementation

[0083] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0084] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0085] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0086] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0087] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0088] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0089] In this application, "multiple" means two or more (including two).

[0090] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0091] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0092] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0093] 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.

[0094] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0095] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0096] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as 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. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0097] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0098] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0099] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0100] 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.

[0101] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0102] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cell 20. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0103] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0104] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0105] In some embodiments, the separator is a separator membrane. The separator membrane can be of various types, and any known porous separator membrane with good chemical and mechanical stability can be selected.

[0106] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0107] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0108] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0109] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0110] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0111] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0112] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0113] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0114] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0115] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0116] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0117] In some implementations, the electrode assembly is a stacked structure.

[0118] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0119] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0120] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0121] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0122] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0123] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0124] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0125] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0126] As an example, a battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include, but are not limited to, square battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0127] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity.

[0128] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0129] In some embodiments, the battery can be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0130] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0131] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0132] Batteries possess outstanding advantages such as high energy density, low environmental pollution, high power density, long lifespan, wide applicability, and low self-discharge coefficient, making them a crucial component of today's new energy development. The development of battery technology must simultaneously consider multiple design factors, such as performance parameters like energy density, cycle life, discharge capacity, and charge / discharge rate. Furthermore, battery reliability must also be taken into account.

[0133] In battery technology, to reduce the risk of explosions and fires in typical battery cells, pressure relief components can be incorporated into the cells. These components release internal pressure, thereby reducing the risk of explosions and fires and improving the reliability of the battery cell. In related technologies, pressure relief components are typically integrally formed into the battery cell's casing using a one-piece molding process, or connected to the casing wall through welding or snap-fit ​​methods. This allows the pressure relief component to actuate and open when the internal pressure or temperature of the battery cell reaches a threshold, releasing the internal pressure. However, battery cells are prone to expansion during use or charging / discharging. The expansion force generated by the battery cell acts on the pressure relief component, making it highly susceptible to tensile deformation and strain. This strain reduces the structural strength of the pressure relief component, leading to poor stability and premature pressure release or fatigue cracking during use. This negatively impacts the battery cell's lifespan and overall reliability.

[0134] Based on the above considerations, in order to alleviate the problem of premature pressure release or fatigue cracking of the pressure relief component of a battery cell during use, this application provides a battery cell including a casing and a pressure relief component; the casing includes a first wall portion; the pressure relief component is disposed on the first wall portion, and the pressure relief component includes a first weak portion, the first weak portion defining at least one predetermined pressure relief area, the pressure relief component being configured to crack along at least a portion of the first weak portion when the battery cell is depressurized; wherein, the sum of the areas of the predetermined pressure relief areas is S, the first weak portion includes at least one first weak segment, the area of ​​the cross-sectional area of ​​the first weak segment perpendicular to its extension direction is S1, satisfying: 300mm 2 ≤S≤1500mm 2 0.006mm 2 ≤S1≤0.15mm 2 .

[0135] The first wall of the outer casing is provided with a pressure relief component, which includes a first weak part. The first weak part can crack when the battery cell is depressurized to release the internal pressure of the battery cell and reduce the occurrence of problems such as explosion and fire caused by excessive internal pressure of the battery cell.

[0136] The sum of the areas of all predetermined pressure relief zones is greater than or equal to 300 mm². 2 This design can alleviate the problem of excessive pressure bearing capacity in the first weakest section of the first weakest part, which leads to excessive burst pressure required by the pressure relief component when depressurizing a battery cell. This reduces the risk of battery cell casing rupture, explosion, or fire due to untimely pressure relief by the pressure relief component, thereby effectively improving the reliability of the battery cell. The sum of the areas of all predetermined pressure relief zones is less than or equal to 1500 mm². 2 This design reduces the stress concentration in the predetermined pressure relief area and the first weakest segment of the first weak part when the expansion force generated by the expansion of the battery cell acts on the pressure relief component during use. It also improves the stress absorption effect of the predetermined pressure relief area, thereby reducing the strain and strain amplitude of the first weakest segment of the pressure relief component. This reduces the risk of premature actuation or fatigue cracking of the battery cell during use, improves the stability of the pressure relief component when the battery cell is in use, and ultimately increases the service life and reliability of the battery cell. The cross-sectional area of ​​the first weakest segment of the first weak part perpendicular to its extension direction is greater than or equal to 0.006 mm². 2 This design reduces the stress concentration in the predetermined pressure relief area and the first weakest segment of the first weak part when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component. It also improves the stress absorption effect of the predetermined pressure relief area, thereby reducing the strain and strain amplitude of the first weakest segment of the pressure relief component. This further reduces the risk of premature actuation or fatigue cracking of the battery cell during use, further improving the stability of the pressure relief component, and ultimately increasing the service life and reliability of the battery cell. The cross-sectional area of ​​the first weakest segment of the first weak part perpendicular to its extension direction is less than or equal to 0.15 mm². 2 This can alleviate the problem of excessive pressure bearing capacity in the first weak section of the first weak part, which causes excessive burst pressure required by the pressure relief component when the battery cell is depressurized. This can reduce the risk of the battery cell casing cracking, exploding, or catching fire due to untimely pressure relief by the pressure relief component, thereby effectively improving the reliability of the battery cell.

[0137] The battery cells disclosed in this application can be used, but are not limited to, in electrical equipment such as vehicles, ships, or aircraft. A power system for such equipment can be constructed using battery cells and batteries as disclosed in this application. This helps to mitigate the problem of premature pressure release or fatigue cracking of the battery cell's pressure relief components during use, thereby improving the reliability and service life of the battery cells.

[0138] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0139] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device according to an embodiment of this application.

[0140] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery 100 is disposed inside the vehicle 1000. The battery 100 can be disposed at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source or general power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 controls the battery 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0141] In some embodiments of this application, the battery 100 can not only serve as the operating power or power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0142] Please refer to Figure 2 and Figure 3 , Figure 2 This is an exploded view of the battery 100 provided in some embodiments of this application. Figure 3 This is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of this application. The battery 100 includes a housing 10 and a battery cell 20, which is housed within the housing 10.

[0143] The housing 10 provides assembly space for the battery cell 20, and can adopt various structures. In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, which overlap each other, and together define an assembly space for accommodating the battery cell 20. The second housing body 12 may be a hollow structure open at one end, and the first housing body 11 may be a plate-like structure, with the first housing body 11 covering the open side of the second housing body 12 so that the first housing body 11 and the second housing body 12 together define the assembly space; alternatively, the first housing body 11 and the second housing body 12 may both be hollow structures open on one side, with the open side of the first housing body 11 covering the open side of the second housing body 12.

[0144] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder, a cuboid, or a cube. For example, in... Figure 2 In the middle, the shape of box 10 is a cuboid.

[0145] In battery 100, there can be one or more battery cells 20 disposed within housing 10. When there are multiple battery cells 20 disposed within housing 10, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed configuration, and then the entire assembly of multiple battery cells 20 is housed within housing 10. Alternatively, battery 100 can also be composed of multiple battery cells 20 first connected in series, in parallel, or in a mixed configuration to form a battery module, and then multiple battery modules are connected in series, in parallel, or in a mixed configuration to form a whole, which is then housed within housing 10.

[0146] In some embodiments, the battery 100 may also include other structures. For example, the battery 100 may also include a busbar for connecting multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20.

[0147] 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 to these. The battery cell 20 can be in the form of a cuboid, cylinder, prism, or other shapes. For example, in... Figure 3 In the middle, the battery cell 20 has a cuboid structure.

[0148] In some embodiments, such as Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7As shown, this application embodiment provides a battery cell 20, which includes a housing 21 and a pressure relief component 22. The housing 21 includes a first wall portion 211. The pressure relief component 22 is disposed on the first wall portion 211 and includes a first weak portion 221. The first weak portion 221 defines at least one predetermined pressure relief area P. The pressure relief component 22 is configured to split along at least a portion of the first weak portion 221 when the battery cell 20 is depressurized. The sum of the areas of all predetermined pressure relief areas P is S. The first weak portion 221 includes at least one first weak segment 2211. The area of ​​the cross-sectional area of ​​the first weak segment 2211 perpendicular to its extension direction is S1, satisfying: 300 mm². 2 ≤S≤1500mm 2 0.006mm 2 ≤S1≤0.15mm 2 .

[0149] Among them, see Figure 4 As shown, the battery cell 20 may also include an electrode assembly 23, which is housed within the housing 21. The electrode assembly 23 is a component in the battery cell 20 where an electrochemical reaction occurs. The structure of the electrode assembly 23 can be varied. For example, the electrode assembly 23 can be a wound structure formed by winding a positive electrode, a separator, and a negative electrode, or a stacked structure formed by arranging a positive electrode, a separator, and a negative electrode in layers.

[0150] For example, the separator is a separator membrane, and the main material of the separator membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0151] The battery cell 20 may include one electrode assembly 23 or multiple electrode assemblies 23. Figure 4 In this embodiment, the battery cell 20 includes two electrode assemblies 23, which are stacked along the thickness direction of the electrode assemblies 23. The stacking direction of the two electrode assemblies 23 can 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 can also be three, four, five, etc.

[0152] In some embodiments, the battery cell 20 further includes an electrolyte housed within the casing 21. The electrolyte may be a liquid electrolyte.

[0153] In some embodiments, the housing 21 may include a housing 212 and an end cap 213. The housing 212 has an internal cavity for accommodating the electrode assembly 23 and has at least one opening 2121. That is, the housing 212 is a hollow structure with at least one end opening 2121. The end cap 213 covers the opening 2121 of the housing 212 and forms a sealed connection to form a closed space for accommodating the electrode assembly 23 and the electrolyte.

[0154] The first wall portion 211, where the pressure relief component 22 is provided, can be the end cap 213 of the outer casing 21, or it can be a wall portion of the housing 212 of the outer casing 21. For example, in... Figure 3 and Figure 4 In this embodiment, the first wall portion 211 is the end cap 213. Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the first wall portion 211 can also be a wall portion that is disposed opposite to the end cap 213, that is, the bottom wall of the housing 212. The first wall portion 211 can also be a side wall that is adjacent to and connected to the end cap 213. The side wall can be a wall that surrounds the end cap 213 and forms an opening 2121.

[0155] When assembling the battery cell 20, the electrode assembly 23 can be placed into the housing 212 first, and the electrolyte can be filled into the housing 212. Then, the end cap 213 can be closed onto the opening 2121 of the housing 212 to complete the assembly of the battery cell 20.

[0156] The housing 212 can have various shapes, such as a cylinder, cuboid, or prism. The shape of the housing 212 can be determined based on the specific shape of the electrode assembly 23. For example, if the electrode assembly 23 is a cylinder, a cylindrical housing 212 can be used; if the electrode assembly 23 is a cuboid, a cuboid housing 212 can be used. Of course, the end cap 213 can also have various structures, such as a plate-like structure or a hollow structure open at one end. For example, in… Figure 3 , Figure 4 In the middle, the shell 212 is a cuboid structure, the length direction Y of the first wall is the length direction of the battery cell 20, the width direction Z of the first wall is the thickness direction of the battery cell 20, and the thickness direction X of the first wall is the height direction of the battery cell 20.

[0157] Of course, it is understandable that the outer casing 21 is not limited to the structure described above. The outer casing 21 can also be other structures. For example, the outer casing 21 can include a housing 212 and two end caps 213. The housing 212 is a hollow structure with openings 2121 formed at both opposite ends. One end cap 213 is fitted onto one opening 2121 of the housing 212 and forms a sealed connection to form a closed space for accommodating the electrode assembly 23 and the electrolyte. That is, the housing 212 has openings 2121 on both opposite sides, and the two end caps 213 are fitted onto both sides of the housing 212 to close the corresponding openings 2121.

[0158] The outer casing 21 can also be made of various materials, such as copper, iron, aluminum, steel or aluminum alloy.

[0159] In some embodiments, the battery cell 20 further includes electrode terminals 24. The electrode terminals 24 may be insulatedly mounted on the housing 21 and are electrically connected to the electrode assembly 23 to output or input electrical energy to the battery cell 20.

[0160] It should be noted that the electrode terminal 24 is insulated and mounted on the housing 21, meaning that there is no electrical connection between the electrode terminal 24 and the housing 21.

[0161] The battery cell 20 may include one electrode terminal 24 or two electrode terminals 24. For example, as shown... Figure 4 As shown, the battery cell 20 includes two electrode terminals 24, which are spaced apart along the length Y direction of the first wall. Each electrode assembly 23 has two tabs 231, which are spaced apart along the length Y direction of the wall. The two tabs 231 have opposite polarities. The two electrode terminals 24 are electrically connected to the two tabs 231 with opposite polarities, respectively, to realize the input or output of the positive and negative electrodes of the battery cell 20.

[0162] It should be noted that one tab 231 of the electrode assembly 23 can be a component formed by stacking and connecting the areas of the positive electrode sheet that are not coated with the positive active material layer, thus forming a positive tab; the other tab can be a component formed by stacking and connecting the areas of the negative electrode sheet that are not coated with the negative active material layer, thus forming a negative tab.

[0163] For example, the electrode terminal 24 can be made of various materials, such as copper, iron, aluminum, steel or aluminum alloy.

[0164] There are various positions in which the electrode terminal 24 is mounted on the housing 21. For example, in Figure 3 and Figure 4In this embodiment, both electrode terminals 24 are mounted on the end cap 213 of the housing 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 may also be mounted on the housing 212 of the housing 21. Similarly, one electrode terminal 24 may be mounted on the housing 212 of the housing 21, and the other electrode terminal 24 may be mounted on the end cap 213 of the housing 21.

[0165] In some embodiments, see Figure 4 As shown, the battery cell 20 may also include two current collectors 25. Both current collectors 25 are disposed inside the housing 21 and are spaced apart along the length direction Y of the first wall. Each current collector 25 is used to connect an electrode terminal 24 and a tab 231 of the same polarity among multiple electrode assemblies 23 to realize the electrical connection between the electrode terminal 24 and the electrode assembly 23, which helps to reduce the assembly difficulty between the tab 231 and the electrode terminal 24.

[0166] For example, the material of the current collector 25 can be various, such as copper, iron, aluminum, steel or aluminum alloy.

[0167] In this embodiment, the pressure relief component 22 plays a pressure relief role in the battery cell 20, and is used to release the internal pressure of the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value.

[0168] The structure of the pressure relief component 22 can be varied, for example, such as Figure 4 As shown, the pressure relief component 22 can be a separate structure from the first wall portion 211 of the outer casing 21, or it can be integrally formed with the first wall portion 211 of the outer casing 21. When the pressure relief component 22 and the first wall portion 211 of the outer casing 21 are separate structures, that is, the first wall portion 211 of the outer casing 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 connection method between the pressure relief component 22 and the first wall portion 211 can be various, such as welding or snap-fitting. When the pressure relief component 22 and the first wall portion 211 of the outer casing 21 are integrally formed, that is, the pressure relief component 22 is a wall of the outer casing 21, that is, the pressure relief component 22 is integrated into the first wall portion 211 and forms a wall of the outer casing 21. Correspondingly, the pressure relief component 22 has a weak structure formed on the first wall portion 211 for cracking when the battery cell 20 is depressurized.

[0169] For example, such as Figure 8 , Figure 9As shown, 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, and the first weak portion 221 and the predetermined pressure relief area P are both formed on the first wall portion 211.

[0170] The pressure relief component 22 includes a first weak portion 221, meaning the first weak portion 221 is a part of the pressure relief component 22. The first weak portion 221 is the region 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 prone to cracking due to increased gas pressure inside the battery cell 20 compared to other regions of the pressure relief component 22. The extension trajectory of the first weak portion 221 is the cracking trajectory of the pressure relief component 22, and the pressure relief component 22 can open a predetermined pressure relief region P after at least a partial cracking of the first weak portion 221, so that the battery cell 20 can release the pressure inside the battery cell 20 from the predetermined pressure relief region P.

[0171] The first weak portion 221 defines at least one predetermined pressure relief area P, that is, the predetermined pressure relief area P is part of the pressure relief component 22. The first weak portion 221 may define one predetermined pressure relief area P. The first weak portion 221 may 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.

[0172] Depending on the structural shape of the first weak portion 221, the predetermined pressure relief region P is formed in different ways. For example, in some embodiments, along the extending 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 region P. For example, as shown... Figures 3-5 The first weak portion 221 extends in an elliptical trajectory, defining a predetermined elliptical pressure relief zone P. In this embodiment, the area S of all predetermined pressure relief zones P is the area of ​​the region 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 closest to the first wall portion 211 in the width direction of the first weak portion 221.

[0173] In other embodiments, along the extending direction of the first weak portion 221, the first weak portion 221 is a non-closed structure, and the predetermined pressure relief area P is defined by the line connecting the first weak portion 221 and its ends. It should be noted that the line connecting the ends of the first weak portion 221 is a virtual line. For example, as... Figure 8 As shown, along the extending direction of the first weak portion 221, the first weak portion 221 is V-shaped. Therefore, 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... Figure 9As shown, the first weak portion 221 is U-shaped along its extension direction. The predetermined pressure relief region P is defined by 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 regions P is the area enclosed by the outer contour of the first weak portion 221 and the line connecting its ends. Figure 8 , Figure 9 The dashed line shown is the line connecting the ends of the first weak part 221. Figure 11 The dashed line in the figure is the line connecting the ends of the two first weak segments 2211 of the first weak part 221 in its extension direction. The two dashed lines together with the first weak part 2211 form two predetermined pressure relief zones P. Figure 17 The two dashed lines parallel to the second groove 225 are the lines connecting the two ends of the two first weak segments 2211 of the first weak part 221 along its extension direction. The two dashed lines and the first weak part 221 together define two predetermined pressure relief zones P.

[0174] The first weak portion 221 includes at least one first weak segment 2211. It should be noted that the first weak segment 2211 of the first weak portion 221 is a structure extending along a smooth trajectory, such as a structure extending along a straight line or an arc. The first weak segment 2211 of the first weak portion 221 can be one or more. If the first weak portion 221 is a straight line structure, an arc structure, or a ring structure, then the first weak portion 221 includes only one first weak segment 2211. If the first weak portion 221 is a "V" shaped structure, a "U" shaped structure, or an "H" shaped structure, then the first weak portion 221 includes multiple first weak segments 2211. For example, in... Figure 5 In the design, the pressure relief component 22 has a first groove 222 on its upper surface. The bottom wall of the first groove 222 forms a first weak section 221. Since the first groove 222 is an annular groove, the first weak section 221 consists of only one weak segment 2211. For example, as... Figure 8 As shown, the pressure relief component 22 is provided with a first groove 222. The bottom wall of the first groove 222 forms a first weak section 221. The first groove 222 includes a connected first groove segment 2221 and a second groove segment 2222, forming a V-shaped first groove 222. The bottom wall of the first groove segment 2221 and the bottom wall of the second groove segment 2222 respectively form a first weak section 2211. The first weak section 221 includes two first weak sections 2211. Figure 9As shown, 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 segment 2221, a second groove segment 2222, and a third groove segment 2223 connected together, forming a U-shaped first groove 222. The first groove segment 2221 and the third groove segment 2223 are arranged opposite to each other, and the second groove segment 2222 connects to the first groove segment 2221. The bottom walls of the first groove segment 2221, the second groove segment 2222, and the third groove segment 2223 each form a first weak segment 2211. The first weak portion 221 includes three first weak segments 2211.

[0175] For example, in Figure 10 In the process, the pressure relief component 22 is provided with a first groove 222, and the bottom wall of the first groove 222 forms a first weak part 221. The first groove 222 includes a first groove segment 2221, a second groove segment 2222, a third groove segment 2223 and a fourth groove segment 2224. The first groove segment 2221 and the third groove segment 2223 are arranged opposite to each other. The second groove segment 2222 connects the first groove segment 2221 and the third groove segment 2223. The fourth groove segment 2224 is located between the first groove segment 2221 and the third groove segment 2223, and the fourth groove segment 2224 is connected to the second groove segment 2222. Therefore, the bottom walls of the first groove segment 2221, the second groove segment 2222, the third groove segment 2223 and the fourth groove segment 2224 all form first weak segments 2211. The first weak part 221 includes four first weak segments 2211.

[0176] The area S1 of the cross-section of the first weak segment 2211 perpendicular to its extension direction is the product of the width of the bottom surface of the groove segment 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 segment 2211.

[0177] In some embodiments, S can be 300 mm 2 400mm 2 500mm 2 600mm 2 700mm 2 800mm 2 900mm 2 1000mm 2 1100mm 2 1200mm 2 1300mm 2 1500mm 2 wait.

[0178] For example, S1 can be 0.006 mm. 2 0.007mm 2 0.01mm2 0.0104mm 2 0.015mm 2 0.02mm 2 0.0225mm 2 0.03mm 2 0.04mm 2 0.0575mm 2 0.05mm 2 0.06mm 2 0.07mm 2 0.075mm 2 0.08mm 2 0.09mm 2 0.1mm 2 0.108mm 2 0.15mm 2 wait.

[0179] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with Embodiments 1-7 and Comparative Examples 1-4. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0180] Example 1

[0181] 1. Preparation of battery cell 20

[0182] 1) Preparation of positive electrode sheet

[0183] LiNi, the positive electrode active material 0.7 Co 0.1 Mn 0.1 A positive electrode slurry is prepared in N-methylpyrrolidone (NMP) using O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF). The solid content of the positive electrode slurry is 50 wt%, and the solid component is 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. After cold pressing, the foil is trimmed, cut, and slit. Then it is dried under vacuum at 85°C for 4 hours to produce the positive electrode sheet.

[0184] 2) Preparation of negative electrode sheet

[0185] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry. The solid content of the negative electrode slurry is 30 wt%, and the mass ratio of graphite, silicon suboxide, Super P, CMC, and binder styrene-butadiene rubber (SBR) in the solid components is 88:7:3:2. The negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C. Then, it is cold-pressed, trimmed, cut into sheets, and slit. Finally, it is dried under vacuum at 120°C for 12 hours to prepare the negative electrode sheet.

[0186] 3) Preparation of electrolytes

[0187] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), the thoroughly 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 mixed evenly to obtain a liquid electrolyte with a concentration of 1 mol / L.

[0188] 4) Isolation components

[0189] A 16μm polyethylene film was used as the separator.

[0190] 5) Preparation of battery cell 20

[0191] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to isolate them. The electrode assembly 23 is then wound up and placed inside an aluminum casing 21. The electrolyte prepared above is injected into the dried casing 21. The process includes encapsulation, settling, formation, shaping, and capacity testing to complete the fabrication of the battery cell 20. The casing 21 of the battery cell 20 has a cuboid structure. The shell 212 of the casing 21 has an opening at one end. The wall of the shell 212 opposite to the end cap 213 is a first wall 211, which is rectangular. A pressure relief component 22 is provided on the first wall 211 of the casing 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 part 221. The first groove 222 has an H-shaped structure and is a three-level groove. The first groove 222 is provided on the outer surface of the first wall portion 211. In the battery cell 20 of Embodiment 1, the area S1 of the cross-section of the first weak segment 2211 of the first weak part 221 of the pressure relief component 22 is 0.006 mm². 2 The sum of the areas of all predetermined pressure relief zones P is S = 1500 mm². 2.

[0192] The preparation methods of the battery cells 20 in Examples 2-7 and Comparative Examples 1-4 are the same as those in Example 1, except that the area S1 of the cross section of the first weak segment 2211 of the first weak part 221 perpendicular to its extension direction and the sum S of the areas of all predetermined pressure relief zones P are different.

[0193] The reliability of the battery cells 20 was evaluated by conducting fatigue tests on the battery cells 20 in Examples 1-7 and Comparative Examples 1-4 to obtain the number of fatigue cycles of the battery cells 20 during long-term use, and by conducting thermal runaway tests on the battery cells 20 to obtain the duration of air suffocation during thermal runaway. The specific details are shown in Table 1.

[0194] The fatigue cycle measurement method for battery cell 20 is as follows:

[0195] 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 housing 212 perpendicular to the width direction Z along the first wall). The first and third steel plates are located at both ends of the fixture and are fixed by bolts. The second steel plate is located between the first and third steel plates and is constrained by guide rails. The second steel plate can only move in a direction perpendicular to the plane of the steel plate.

[0196] 2) The battery cell 20 is installed between the first steel plate and the second steel plate. A support structure is placed between the large surface of one side of the battery cell 20 and the first steel plate, and between the large surface of the other side and the second steel plate. The support structure can be a heat 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 charge-discharge cycle aging. 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.

[0197] 3) Adjust the position of the second steel plate by adjusting the bolt preload to adjust the initial compressive force of the battery cell 20. Fix a battery cell 20 into a special test fixture, adjust the bolt preload, observe the pressure sensor, and make the initial compressive force on the battery cell 20 2000N. Then connect the two electrical connection parts (positive electrode terminal and negative electrode terminal) of the battery cell 20 to the charging and discharging equipment.

[0198] 4) Place the battery cell 20 and the fixture in a constant temperature environment of 25±2℃, and start the test after the battery cell 20 reaches temperature equilibrium.

[0199] 5) The test procedure shall be performed in accordance with the "Standard Cycle Life" section 6.4 of "GBT31484-2015 Requirements and Test Methods for Cycle Life of Power Batteries for Electric Vehicles", and the test cycle cutoff condition shall be changed to "the test shall be stopped when the pressure relief component 22 is damaged at the first groove 222".

[0200] Specifically, test according to the following steps:

[0201] a) Discharge to 2.8V with a current of 1I1(A);

[0202] b) Let it rest for no less than 30 minutes;

[0203] c) Charge according to method 6.1.1.3 of GB / T 31484-2015 "Requirements and Test Methods for Cycle Life of Power Batteries for Electric Vehicles";

[0204] d) Let it rest for no less than 30 minutes;

[0205] e) Discharge to 2.8V with a current of 1I1(A);

[0206] f) Repeat steps b) to e) until the first groove 222 of the pressure relief component 22 breaks, then stop the test.

[0207] The test process involves continuously observing the area where the pressure relief component 22 of the battery cell 20 has the first groove 222 until the area breaks and leaks liquid. The number of cycles is recorded as the cycle fatigue number of the battery cell 20. The more cycle fatigue numbers the battery cell 20 has, the lower the probability of leakage due to gas generation during long-term use, and the longer its service life.

[0208] The thermal runaway test method for a single battery cell is as follows:

[0209] 1. Select a heating plate according to the size of the battery cell 20. The size of the heating plate should cover the largest surface of the battery cell 20 as much as possible (coverage area ≥ 60%).

[0210] 2. Before testing, charge battery cell 20 to 100% SOC and ensure that the temperature of battery cell 20 is 25±5℃;

[0211] 3. Sensor arrangement:

[0212] 1) Arrangement of temperature sensing wires: Apply a layer of Teflon to the center area of ​​each of the two large surfaces of the battery cell 20, arrange the temperature sensing wires on top of the Teflon, and then apply another layer of Teflon.

[0213] 2) Voltage sampling line arrangement: Apply a layer of Teflon to the positive electrode terminal, negative electrode terminal and outer casing 21 of the battery cell 20, arrange the voltage sampling line on top of the Teflon, and then apply another layer of Teflon.

[0214] 3) Air tube arrangement: Drill a hole in the first wall 211 of the outer shell 21 of the battery cell 20 along the length Y of the first wall. The drilling position is located at the center of the edge of the first groove 222 and the side of the shell 212 (the outer surface of the wall adjacent to the first wall 211 along the length Y of the first wall of the shell 212). Insert the air tube into the hole and seal it. Connect the air tube to the air pressure sensor.

[0215] 4) Connect the temperature sensing wire, voltage sampling wire, and barometric pressure sensor to the data acquisition instrument to collect and analyze data in real time. The data acquisition frequency of the data acquisition instrument is ≤0.1s.

[0216] 4. Assemble the fixture so that it completely covers the large surface of the battery cell 20 (the outer surface of the housing 212 in the width direction Z perpendicular to the first wall). The clamping force is 3000N. Note: The arrangement order of the fixture, heating plate and battery cell is: fixture + heating plate + battery cell + fixture.

[0217] 5. Test: Turn on the data acquisition device to collect temperature, voltage, and air pressure data, and then turn on the heating plate at 500W to heat the battery cells until the battery cells thermally run away.

[0218] 6. Obtain the holding time of 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 obtain the holding time of battery cell according to the formula: holding time = valve opening moment - thermal runaway moment.

[0219] Thermal runaway determination criteria: a) The triggering object experiences a voltage drop that exceeds 25% of the initial voltage; b) The temperature at the detection point reaches the manufacturer's specified maximum operating temperature; c) The temperature rise rate at the detection point, dT / dt, is ≥1℃ / s and lasts for more than 3s. When a) and c) or b) and c) occur, thermal runaway is determined, and the moment of thermal runaway is identified.

[0220] Valve opening time determination: When the gas pressure drops by more than 25%, it can be determined that the valve has opened (at least partially cracked along the first weak point 221). The moment when the gas pressure begins to drop is the valve opening time. Both the valve opening time and the thermal runaway time can be obtained from the data acquisition unit.

[0221] Table 1:

[0222]

[0223] As shown in Table 1, as S gradually decreases, the time for the battery cell 20 to hold its pressure increases, meaning that as S gradually decreases, the timely pressure relief of the battery cell 20 becomes worse, and the risk of explosion during thermal runaway is higher. As S gradually decreases, the number of fatigue cycles of the battery cell 20 gradually increases, meaning that as S gradually decreases, the possibility of fatigue-induced valve opening and leakage in the battery cell 20 during long-term use gradually decreases.

[0224] As S1 gradually increases, the time for the battery cell 20 to hold its pressure increases. In other words, as S1 gradually increases, the timely pressure relief of the battery cell 20 becomes worse, and the risk of explosion in the event of thermal runaway of the battery cell 20 is higher. As S1 gradually increases, the fatigue cycle of the battery cell 20 gradually increases. In other words, as S1 gradually increases, the possibility of fatigue-induced valve opening and leakage of the battery cell 20 during long-term use gradually decreases.

[0225] Table 1 shows the values ​​of S when S is 100 mm², 150 mm², and when S1 is 0.4 mm². 2 0.3mm 2 At that time, the holding time of battery cell 20 was 5.4s and 5.3s, respectively, which is much longer than the holding time of S (300mm). 2 400mm 2 600mm 2 800mm 2 1000mm 2 1200mm 2 1500mm 2 When and S1 is 0.15mm 2 0.1mm 2 0.06mm 2 0.04mm 2 0.01mm 2 0.006mm 2 The breath-holding time, that is, the breath-holding time of battery cell 20 in Comparative Example 3 and Comparative Example 3, is much longer than the breath-holding time of battery cell 20 in Examples 1-7, Comparative Example 1 and Comparative Example 2. Therefore, when S≥300mm2 and S1≤0.15mm 2 The shorter holding time during thermal runaway of the battery cell 20 increases the likelihood of timely pressure relief by the pressure relief component 22 of the battery cell 20, reducing the risk of the casing 21 of the battery cell 20 bursting, exploding, or catching fire due to untimely pressure relief by the pressure relief component 22.

[0226] When S is 2000mm 2 1700mm 2 When and S1 is 0.004mm 2 0.005mm 2The fatigue cycles of battery cell 20 are 672 and 814, respectively, which are much smaller than the fatigue cycle of S (1500 mm). 2 1200mm 2 1000mm 2 800mm 2 600mm 2 400mm 2 300mm 2 150mm 2 100mm 2 When and S1 is 0.006mm 2 0.01mm 2 0.04mm 2 0.06mm 2 0.1mm 2 0.15mm 2 0.3mm 2 0.4mm 2 The fatigue cycles of battery cell 20, i.e., the fatigue cycles of battery cells 20 in Comparative Examples 1 and 2, are less than the fatigue cycles of battery cells 20 in Examples 1-7, Comparative Examples 3 and 4. Therefore, when S≤1500mm 2 When S1 ≥ 0.006 mm 2 This results in the battery cell 20 having a higher fatigue life, thereby reducing the risk of leakage caused by phenomena such as 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.

[0227] Therefore, 300mm 2 ≤S≤1500mm 2 0.006mm 2 ≤S1≤0.15mm 2 This design can reduce the risk of the battery cell 20's casing 21 bursting, exploding, or catching fire due to untimely pressure relief by the pressure relief component 22, as well as the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 at the corresponding position of the first groove 222 after long-term use. This improves the stability of the pressure relief component 22 and enhances the service life and reliability of the battery cell 20.

[0228] In summary, the sum of the areas of all predetermined pressure relief zones P is greater than or equal to 300 mm². 2This design can alleviate the problem of excessive pressure bearing capacity in the first weak section 2211 of the first weak part 221, which leads to excessive burst pressure required by the pressure relief component 22 when depressurizing the battery cell 20. This reduces the risk of the battery cell 20's casing 21 bursting, exploding, or catching fire due to untimely pressure relief by the pressure relief component 22, thereby effectively improving the reliability of the battery cell 20. The sum of the areas of all predetermined pressure relief zones P is less than or equal to 1500 mm², which reduces the stress concentration in the predetermined pressure relief zone P and the first weak section 2211 of the first weak part 221 when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22. It also improves the stress absorption effect of the predetermined pressure relief zone P, thereby reducing the strain and strain amplitude of the first weak part 221 of the pressure relief component 22. This reduces the risk of premature activation or fatigue cracking of the battery cell 20 during use, improves the stability of the pressure relief component 22 when the battery cell 100 is in use, and ultimately improves the service life and reliability of the battery cell 20. Furthermore, the cross-sectional area of ​​the first weak segment 2211 of the first weak part 221 perpendicular to its extension direction is greater than or equal to 0.006 mm2. This reduces the stress concentration in the predetermined pressure relief zone P and the first weak segment 2211 of the first weak part 221 when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22. It also improves the stress absorption effect of the predetermined pressure relief zone P, thereby reducing the strain and strain amplitude of the first weak part 221 of the pressure relief component 22. This further reduces the risk of premature activation or fatigue cracking of the battery cell 20 during use. Improving the stability of the pressure relief component 22, thereby improving the service life and reliability of the battery cell 20; the cross-sectional area of ​​the first weak section 2211 of the first weak part 221 perpendicular to its extension direction is less than or equal to 0.15 mm2, 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 excessive burst pressure required by the pressure relief component 22 when the battery cell 20 is depressurized, thereby reducing the risk of the outer shell 21 of the battery cell 20 bursting, exploding, or catching fire due to the untimely pressure relief by the pressure relief component 22, and thus effectively improving the reliability of the battery cell 20.

[0229] In some embodiments, 400mm²≤S≤1200mm², 0.01mm²≤S1≤0.1mm².

[0230] For example, S can be 400mm 2 600mm 2 800mm 2 1000mm 2 1050mm 2 1200mm 2 wait.

[0231] For example, S1 can be 0.01 mm. 2 0.02mm 2 0.03mm 2 0.04mm 2 0.05mm 2 0.06mm 2 0.07mm 2 0.075mm 2 0.08mm 2 0.09mm 2 0.1mm 2 wait.

[0232] Please continue referring to Table 1, where S is 1500mm. 2 1200mm 2 1000mm 2 800mm 2 600mm 2 400mm 2 The relative length S is 300mm 2 When and S1 is 0.01mm 2 0.04mm 2 0.06mm 2 0.1mm 2 The relative length to S1 is 0.15 mm. 2 The shorter the breath-holding time, the lower the probability of explosion in the event of thermal runaway of a single battery cell (20 mm²). Therefore, S ≥ 400 mm² and S1 ≤ 0.1 mm². 2 The shorter holding time during thermal runaway of the battery cell 20 further increases the likelihood of timely pressure relief by the pressure relief component 22 of the battery cell 20, thereby further reducing the risk of explosion during thermal runaway of the battery cell 20.

[0233] When S is 1200mm 2 1000mm 2 800mm 2 600mm 2 400mm 2 300mm 2 The relative length S is 1500mm 2 When and S1 is 0.01mm 2 0.04mm 2 0.06mm 2 0.1mm 2 0.15mm 2 The relative length to S1 is 0.006 mm. 2The battery cells undergo more fatigue cycles, and the probability of leakage due to valve opening is lower during long-term use. Therefore, S≤1200mm 2 And S1≥0.04mm 2 This results in a longer fatigue life for the battery cell 20, and further reduces the probability of leakage due to gas generation during long-term use of the battery cell 20.

[0234] In summary, the sum of the areas of all predetermined pressure relief zones P is further limited to be greater than or equal to 400 mm². 2 This can further alleviate the problem of excessive pressure bearing capacity in the first weak section 2211 of the first weak part 221, which causes excessive burst pressure required by the pressure relief component 22 when depressurizing the battery cell 20. This further reduces the risk of the battery cell 20's casing 21 bursting, exploding, or catching fire due to untimely pressure relief by the pressure relief component 22, thereby effectively improving the reliability of the battery cell 20. The sum of the areas of all predetermined pressure relief zones P is less than or equal to 1200 mm². 2 This design can further reduce the stress concentration in the predetermined pressure relief zone P and the first weak segment 2211 of the first weak part 221 when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22. It can also further improve the stress absorption effect of the predetermined pressure relief zone P, thereby further reducing the strain and strain amplitude of the first weak part 221 of the pressure relief component 22. This further reduces the risk of premature activation or fatigue cracking of the battery cell 20 during use, further improving the stability of the pressure relief component 22, and ultimately increasing the service life and reliability of the battery cell 20. Furthermore, the area of ​​the cross-section of the first weak segment 2211 of the first weak part 221 perpendicular to its extension direction is further limited to greater than or equal to 0.01 mm². 2 This design can further reduce the stress concentration in the predetermined pressure relief zone P and the first weak segment 2211 of the first weak part 221 when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22. It can also further improve the stress absorption effect of the predetermined pressure relief zone P, thereby further reducing the strain and strain amplitude of the first weak part 221 of the pressure relief component 22. This further reduces the risk of premature activation or fatigue cracking of the battery cell 20 during use, further improving the stability of the pressure relief component 22, and ultimately increasing the service life and reliability of the battery cell 20. The cross-sectional area of ​​the first weak segment 2211 of the first weak part 221 perpendicular to its extension direction is less than or equal to 0.1 mm². 2This can further 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 excessive burst pressure required by the pressure relief component 22 when the battery cell 20 is depressurized. This can further reduce the risk of the outer shell 21 of the battery cell 20 bursting, exploding, or catching fire due to the untimely pressure relief by the pressure relief component 22, thereby further improving the reliability of the battery cell 20.

[0235] In some embodiments, 0.000002≤S1 / S≤0.001.

[0236] The ratio S1 / S is the cross-sectional area S1 of the first weak segment 2211 perpendicular to its extension direction to the sum of the areas S of all predetermined pressure relief zones P. It can be 0.000002, 0.00000294, 0.000004, 0.000005, 0.00000538, 0.0000083, 0.00000909, 0.00001, 0.00003333, 0.00005, 0.00007, 0.00009, 0.0001, 0.00016, 0.00025, 0.0005, 0.0007, 0.0009, 0.001, etc.

[0237] Therefore, by setting the ratio of the area of ​​the cross-section of the first weak segment 2211 perpendicular to its extension direction to the sum of the areas of all predetermined pressure relief zones P to between 0.000002 and 0.001, the relative size of the cross-section area of ​​the first weak segment 2211 perpendicular to its extension direction to the sum of the areas of all predetermined pressure relief zones P is set more reasonably. Setting the ratio to be greater than or equal to 0.000002, when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22, the stress concentration of the first weak segment 2211 of the first weak part 221 can be reduced, and the predetermined pressure relief zones P can absorb part of the expansion force, thereby... This effectively mitigates the tensile deformation of the first weak section 2211 of the first weak part 221 of the pressure relief component 22, thereby reducing the strain and strain amplitude of the first weak section 2211 of the first weak part 221 of the pressure relief component 22. This reduces the deformation of the first weak section 2211, thus mitigating the structural strength reduction caused by excessive strain and strain amplitude in the first weak part 221 of the pressure relief component 22. This reduces the risk of leakage caused by premature activation or fatigue cracking of the first weak part 221 of the pressure relief component 22 after long-term use of the battery cell 20, thereby improving the stability of the pressure relief component 22 and enhancing the service life and reliability of the battery cell 20. The ratio is set to less than or equal to 0.001 to 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 excessive burst pressure required by the pressure relief component 22 when the battery cell 20 is depressurized. This can reduce the risk of the outer casing 21 of the battery cell 20 bursting, exploding, or catching fire due to the untimely pressure relief by the pressure relief component 22, thereby effectively improving the reliability of the battery cell 20.

[0238] In some embodiments, 0.000004 ≤ S1 / S ≤ 0.0005.

[0239] For example, S1 / S can be 0.000004, 0.000006, 0.000008, 0.00002, 0.00004, 0.00005, etc.

[0240] In summary, by setting the ratio of the area of ​​the cross-section of the first weak segment 2211 perpendicular to its extension direction to the sum of the areas of all predetermined pressure relief zones P to between 0.000004 and 0.0005, and by setting the ratio of the area of ​​the cross-section of the first weak segment 2211 perpendicular to its extension direction to the sum of the areas of all predetermined pressure relief zones P to be greater than or equal to 0.000004, the deformation of the first weak segment 2211 can be further reduced when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22. This can reduce the phenomenon of reduced structural strength of the first weak part 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 first weak part 221 of the pressure relief component 22 after long-term use of the battery cell 20. This further improves the stability of the pressure relief component 22 and further improves 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 sum of the areas of all predetermined pressure relief zones P is less than or equal to 0.0005. This further alleviates the phenomenon that the pressure-bearing capacity of the first weak section 2211 of the first weak part 221 is too large, resulting in excessive burst pressure required by the pressure relief component 22 when the battery cell 20 is depressurized. This can further reduce the risk of the outer casing 21 of the battery cell 20 bursting, exploding, or catching fire due to the untimely pressure relief by the pressure relief component 22, thereby effectively improving the reliability of the battery cell 20.

[0241] In some embodiments, see Figure 6 and Figure 7 As shown, the pressure relief component 22 is provided with a first groove 222, which includes at least one groove segment. The pressure relief component 22 forms at least one first weak segment 2211 in the area where the groove segment is provided. The width of the bottom surface of the groove segment is A, and the thickness of the first weak segment 2211 is H, satisfying: S1=A×H; 0.1mm≤A≤0.3mm; 0.06mm≤H≤0.5mm.

[0242] Wherein, the width A of the bottom surface of the groove segment can be the dimension of the bottom surface of the groove segment in its width direction. The thickness of the first weak segment 2211 is the dimension of the first weak segment 2211 along the thickness direction X of the first wall portion.

[0243] At the corners of the bottom and sides of the trough section, rounded or chamfered transitions are formed. When measuring the width A of the bottom of the trough section, the dimensions of the rounded corners should be excluded. In other words, the cross-sectional area of ​​the first weak segment 2211 is calculated by multiplying the width of the bottom of the trough section by the thickness of the first weak segment 2211 formed by the trough section. When measuring the width of the bottom of the trough section and the thickness of the first weak segment 2211 formed by the trough section, the measurement should be taken in areas other than the rounded or chamfered corners between the sides and the bottom of the trough.

[0244] If the groove segment has rounded corners or chamfers at both ends in the extension direction, the area of ​​the cross-section of the first weak segment 2211 is calculated by multiplying the width of the groove bottom surface of the groove segment by the thickness of the first weak segment 2211 formed by the groove segment. When measuring the width of the groove bottom surface of the groove segment and the thickness of the first weak segment 2211 formed by the groove segment, the measurement should be taken in areas other than the rounded corners or chamfers at both ends in the extension direction of the groove segment.

[0245] For example, the width A of the bottom surface of the groove segment can be 0.1mm, 0.13mm, 0.15mm, 0.17mm, 0.19mm, 0.2mm, 0.23mm, 0.25mm, 0.27mm, 0.29mm, 0.3mm, etc.

[0246] For example, the thickness H of the first weak segment 2211 can be 0.06mm, 0.08mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, etc.

[0247] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, further detailed descriptions will be provided below in conjunction with embodiments 8-12. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0248] The preparation method of the battery cell 20 in Examples 8-12 is the same as that in Example 1 above. The difference between the battery cells 20 in Examples 15-23 is that the width A of the bottom wall of the tank segment and the thickness H of the first weak part 221 are different, as shown in Table 2.

[0249] Table 2:

[0250]

[0251]

[0252] As A increases, the stress concentration of the first weak part 221 formed in the corresponding area of ​​the groove is smaller, the first weak section 2211 of the first weak part 221 has a greater ability to withstand deformation, the burst pressure of the pressure relief component 22 is greater, the probability of the battery cell 20 leaking liquid due to gas generation during long-term use gradually decreases, and the probability of the battery cell 20 exploding when thermal runaway gradually increases.

[0253] As H increases, the first weak section 2211 of the first weak part 221 has a greater ability to resist deformation, the first weak part 221 has a greater ability to withstand air pressure, the pressure relief component 22 has a greater burst pressure, the probability of the battery cell 20 leaking liquid due to gas generation during long-term use gradually decreases, and the probability of the battery cell 20 exploding when thermal runaway gradually increases.

[0254] As can be seen from Tables 1 and 2, when the width A of the bottom surface of the tank section is greater than or equal to 0.1 mm and the thickness H of the first weak part 221 is greater than or equal to 0.06 mm, the fatigue number of the battery cell 20 is greater than 1253, which gives the battery cell 20 a high fatigue life and can reduce the risk of leakage during long-term use of the battery cell 20.

[0255] When the width A of the bottom surface of the tank section is less than or equal to 0.3 mm and the thickness H of the first weak part 221 is less than or equal to 0.5 mm, the air-holding time of the battery cell 20 is less than or equal to 3.2 s, so that the risk of explosion and fire when the battery cell 20 thermally runs away is small.

[0256] Therefore, the area S1 of the cross-section of the first weak segment 2211 of the first weak part 221 perpendicular to its extension direction is the product of the width A of the bottom surface of the groove segment and the thickness H of the first weak part 221. The width A of the bottom surface of the groove segment is set to 0.1 mm to 0.3 mm, and the thickness H of the first weak part 221 is set to 0.06 mm to 0.5 mm. By setting the width A of the bottom surface of the groove segment to be greater than or equal to 0.1 mm and the thickness H of the first weak part 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 segment 2211 of the first weak part 221 can be reduced, and the stress absorption effect of the predetermined pressure relief zone P can be improved. This can further reduce the strain and strain amplitude of the first weak part 221 of the pressure relief component 22, and further reduce the risk of premature actuation or fatigue cracking of the pressure relief component 22 during the use of the battery cell 20. By setting the width A of the bottom surface of the first groove 222 to be less than or equal to 0.3 mm and the thickness H of the first weak part 221 to be less than or equal to 0.5 mm, the burst pressure required by the pressure relief component 22 during pressure relief can be reduced, thereby further reducing the risk of the outer casing 21 of the battery cell 20 bursting, exploding, or catching fire due to the untimely pressure relief of the pressure relief component 22.

[0257] In some embodiments, 0.15mm≤A≤0.25mm, 0.1mm≤H≤0.3mm.

[0258] Please continue to refer to Table 2. When the width A of the bottom surface of the tank section is greater than or equal to 0.15 mm and the thickness H of the first weak part 221 is greater than or equal to 0.1 mm, the battery cell 20 has a greater number of fatigue cycles, which makes the battery cell 20 have a higher fatigue life and can further reduce the risk of leakage during long-term use of the battery cell 20.

[0259] When the width A of the bottom surface of the tank section is less than or equal to 0.25 mm and the thickness H of the first weak part 221 is less than or equal to 0.3 mm, the suffocation time of the battery cell 20 is shorter, so that the risk of explosion and fire when the battery cell 20 thermally runs away is smaller.

[0260] Therefore, by setting the width A of the bottom surface of the first groove 222 to be greater than or equal to 0.15 mm and the thickness H of the first weak part 221 to be greater than or equal to 0.1 mm, the concentration of stress generated by the expansion of the battery cell 20 in the first weak section 2211 of the first weak part 221 can be further reduced, and the stress absorption effect of the predetermined pressure relief zone P can be further improved. This can further reduce the strain and strain amplitude of the first weak part 221 of the pressure relief component 22, and further reduce the risk of premature actuation or fatigue cracking of the pressure relief component 22 during the use of the battery cell 20. By setting the width A of the bottom surface of the first groove 222 to be less than or equal to 0.25 mm and the thickness H of the first weak part 221 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 the outer casing 21 of the battery cell 20 bursting, exploding, or catching fire due to untimely pressure relief by the pressure relief component 22.

[0261] like Figure 12 , Figure 13 As shown, along the thickness direction X of the first wall, the maximum groove depth of the first groove 222 is H1, and the thickness of the pressure relief component 22 is D, where 0.16≤H1 / D<1.

[0262] H1 / D can take any one of the following point values ​​or a range between any two: 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.

[0263] It is understandable that if the pressure relief component 22 is integrally formed with the first wall portion 211, 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.

[0264] In this embodiment, 0.16≤H1 / D<1 ensures that the maximum depth of the first groove 222 is not too small as a proportion of the thickness of the pressure relief component 22, thus preventing the burst pressure of the battery cell 20 from being too high and improving the timeliness of pressure relief of the battery cell 20.

[0265] In some embodiments, 0.4mm≤H1≤2mm, 0.8mm≤D≤2.5mm.

[0266] H1 can be any one of the following values ​​or a range between any two: 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.

[0267] D can be any one of the following values ​​or a range between any two: 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.

[0268] In this embodiment, 0.4mm≤H1≤2mm and 0.8mm≤D≤2.5mm ensure that the maximum depth of the first groove 222 and the thickness of the pressure relief component 22 are within a reasonable range, resulting in better economy. In the embodiment where the first wall portion 211 serves as the pressure relief component 22, the thickness of the first wall portion 211 is 0.8mm~2.5mm. A thickness greater than or equal to 0.8mm provides sufficient strength, while a thickness less than or equal to 2mm prevents excessive thickness. Given a fixed volume of the outer casing 21, this allows for an increase in the internal space of the outer casing 21, providing more space for the electrode assembly 23. By controlling the thickness of the first wall portion 211 within the range of 0.8mm~2.5mm, the maximum groove depth of the first groove 222 is controlled within the range of 0.4mm~2mm, resulting in a better match between the maximum groove depth of the first groove 222 and the thickness of the pressure relief component 22, thus ensuring good pressure relief capability of the pressure relief component 22.

[0269] like Figures 11-16 As shown, in some embodiments, the pressure relief component 22 has a first surface 223 and a second surface 224 disposed opposite to each other in the thickness direction X of the first wall portion. The first groove 222 is a multi-level groove. The multi-level grooves are arranged sequentially along the direction from the first surface 223 to the second surface 224. In two adjacent grooves, the first-level groove away from the first surface 223 is disposed on the bottom surface of the first-level groove close to the first surface 223.

[0270] In other words, the pressure relief component 22 has a multi-level stepped groove structure arranged sequentially from the first surface 223 to the second surface 224. The stepped groove structure can be formed by one or more stamping processes. The stepped groove structure can also be formed by multiple etching processes.

[0271] In embodiments where the first groove 222 includes multiple groove segments, each groove segment may also be a multi-level groove structure.

[0272] By setting the first groove 222 as a stepped groove structure along the thickness direction X of the first wall, the first groove 222 is formed by multiple processing steps. With this structure, when forming the first weak part 221 of the same thickness, on the one hand, the depth of a single processing step of the scoring groove can be reduced, which helps to reduce the manufacturing difficulty and the demand on manufacturing equipment for forming the first weak part 221 of the same thickness, thereby reducing manufacturing costs. It can also reduce the forming force on the pressure relief component 22 during a single processing step in the formation of the first weak part 221, which helps to reduce the risk of cracking of the pressure relief component 22, thereby improving the production quality of the battery cell 20. On the other hand, it can improve the material flow pattern of the first weak part 221 during the formation process, which is conducive to the flow of material generated during the formation of the first weak part 221, thereby improving the consistency of the structure of the multi-stage scoring groove.

[0273] In embodiments where the first groove 222 includes multiple groove segments, each groove segment may also be a three-level groove structure.

[0274] For example, such as Figures 11-16 As shown, the first groove 222 includes three levels of scoring grooves, which are arranged sequentially along the direction from the first surface 223 to the second surface 224. The three levels of scoring grooves can be defined as a first sub-groove 222a, a second sub-groove 222b, and a third sub-groove 222c. The first sub-groove 222a, the second sub-groove 222b, and the third sub-groove 222c are arranged sequentially from the first surface 223 to the second surface 224. The second sub-groove 222b is located on the bottom surface of the first sub-groove 222a, and the third sub-groove 222c is located on the bottom surface of the second sub-groove 222b.

[0275] For example, such as Figures 11-16As shown, 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 segment 222b1 is located on the bottom surface of the first segment 222a1, and the seventh segment 222c1 is located on the bottom surface of the fourth segment 222b1. The first segment 222a1, the fourth segment 222b1, and the seventh segment 222c1 together form the first segment 2221. The fifth segment 222b2 is located on the bottom surface of the second segment 222a2, and the eighth segment 222c2 is located on the bottom surface of the fifth segment 222b2. The second segment 222a2, the fifth segment 222b2, and the eighth segment 222c2 together form the second segment 2222. The sixth segment 222b3 is located on the bottom surface of the third segment 222a3, and the ninth segment 222c3 is located on the bottom surface of the sixth segment 222b3. The third segment 222a3, the sixth segment 222b3, and the ninth segment 222c3 together form the third segment 2223.

[0276] The first groove 222 includes three levels of scoring grooves. When forming the first weak part 221 of the same thickness, it can reduce the depth of a single processing of the scoring groove, which helps to reduce the manufacturing difficulty and the demand for manufacturing equipment in forming the first weak part 221 of the same thickness, thereby reducing manufacturing costs. It can also reduce the forming force on the pressure relief component 22 during a single processing of the first weak part 221, which helps to reduce the risk of cracking of the pressure relief component 22, thereby improving the production quality of the battery cell 20. On the other hand, it can improve the flow pattern of the first weak part 221 during the formation process, which is conducive to the flow of the material generated during the formation of the first weak part 221, thereby improving the structural consistency of the multi-level scoring groove. It also alleviates the problem of increased processing time caused by multiple processing required to form the first weak part 221.

[0277] Of course, in other embodiments, the pressure relief component 22 may also be provided with a secondary groove, a quaternary groove, a quinary groove, or a sixth groove.

[0278] like Figures 17-20 As shown, in some embodiments, the pressure relief component 22 further includes a second weak portion 228, which is configured to guide the opening of a predetermined pressure relief zone P.

[0279] 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. More specifically, the thickness of the second weak portion 228 is greater than the thickness of the first weak segment 2211 of the first weak portion 221. The second weak portion 228 is configured to guide the predetermined pressure relief zone P to flip when the first weak portion 221 cracks, thereby releasing the internal pressure of the battery cell 20. Figures 18-20 As shown, the thickness of the second weak part 228 is M, where M>H.

[0280] The thickness of the second weak portion 228 is greater than the thickness of the first weak portion 221, allowing the pressure relief component 22 to preferentially crack 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 cracks. In other words, after the first weak portion 221 cracks, the predetermined pressure relief area P can flip around the second weak portion 228 as a flipping axis, so that after the predetermined pressure relief area P flips, the interior and exterior of the outer casing 21 can communicate with each other for pressure relief.

[0281] The second weak part 228 can guide the opening of the predetermined pressure relief zone P, thereby improving the opening effect of the predetermined pressure relief zone P of the pressure relief component 22. This is beneficial to increasing the pressure relief area of ​​the battery cell 20 after the predetermined pressure relief zone P is opened, thereby increasing the pressure relief rate of the battery cell 20 when thermal runaway occurs. This reduces the risk of fire, explosion, connection failure, etc. caused by untimely pressure relief of the battery cell 20, and helps to improve the reliability of the battery cell 20.

[0282] There are various ways to form the second weak part 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 part 228 in the area where the second groove 225 is provided.

[0283] Understandably, the bottom wall of the second groove 225 forms a second weak portion 228. That is, the pressure relief component 22 is provided with the position of the second groove 225, and the portion corresponding to the bottom surface of the second groove 225 is the second weak portion 228. Of course, in other embodiments, the second weak portion 228 can also be other structures. For example, by performing local heat treatment on the pressure relief component 22 to weaken the strength of that area, the second weak portion 228 can be formed.

[0284] The pressure relief component 22 is provided with a second groove 225, which makes the pressure relief component 22 form a second weak part 228 in the area corresponding to the second groove 225. The battery cell 20 with this structure is easy to form the second weak part 228 on the pressure relief component 22, which helps to reduce the difficulty of forming the second weak part 228 on the pressure relief component 22 and improve the production efficiency of the battery cell 20.

[0285] In some embodiments, a second groove 225 is provided on the surface of the pressure relief member 22 facing the interior of the housing 21.

[0286] The surface of the pressure relief component 22 facing the inside of the outer casing 21 is the surface of the pressure relief component 22 facing the electrode assembly 23. The second groove 225 is disposed on the surface of the pressure relief component 22 facing the inside of the outer casing 21, that is, the second groove 225 is disposed on the surface of the pressure relief component 22 facing the electrode assembly 23, and 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.

[0287] For example, in Figure 17 In the middle, the second groove 225 is a strip structure and is parallel to the second groove segment 2222, so that the second weak part 228 is a strip structure, thereby facilitating the predetermined pressure relief area P to flip around the second weak part 228 after it is opened.

[0288] By setting the second groove 225 on the surface of the pressure relief component 22 facing the inside of the housing 21, the predetermined pressure relief area P can be flipped outward of the housing 21 after being opened around the bottom wall of the groove 225. This reduces the interference effect of the groove side 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.

[0289] Of course, in other embodiments, the second groove 225 may also be disposed on the side of the pressure relief component 22 away from the electrode assembly 23.

[0290] like Figure 19 , Figure 20 As shown, in some embodiments, the pressure relief component 22 has a first surface 223 and a second surface 224 disposed opposite to each other 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. 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.

[0291] The first surface 223 and the second surface 224 are respectively the opposite sides of the pressure relief component 22 in the thickness direction X of the first wall. Along the thickness direction 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.

[0292] For example, a first groove 222 is disposed on the surface of the pressure relief component 22 facing away from the inside of the outer casing 21, and a second groove 225 is disposed on the surface of the pressure relief component 22 facing the inside of the outer casing 21, so that the first groove 222 and the second groove 225 are respectively disposed on both sides of the pressure relief component 22.

[0293] By setting 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 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, which helps to reduce the mutual influence between the first groove 222 and the second groove 225 during the processing.

[0294] In some embodiments, the first surface 223 is the surface of the pressure relief component 22 that faces away from the inside of the housing 21, and the second surface 224 is the surface of the pressure relief component 22 that faces the inside of the housing 21.

[0295] That is, the first groove 222 is provided on the surface of the pressure relief component 22 away from the inside of the outer shell 21, and the second groove 225 is provided on the surface of the pressure relief component 22 facing the inside of the outer shell 21.

[0296] By respectively setting 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 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, which helps to reduce the mutual influence between the first groove 222 and the second groove 225 during the processing. Furthermore, setting the second groove 225 on the second surface 224 of the pressure relief component 22 facing the inside of the outer shell 21 allows the predetermined pressure relief area P to flip outwards from the outer shell 21 after being opened, around the bottom wall of the second groove 225. This reduces the interference effect of the side surface of the second groove 225 on the predetermined pressure relief area P during the flipping process, thus improving the flipping effect of the predetermined pressure relief area P.

[0297] In some embodiments, the first groove 222 and the second groove 225 do not contact each other.

[0298] Understandably, the first groove 222 and the second groove 225 do not intersect. In an embodiment where the pressure relief component 22 is provided with multi-level grooves, and the first groove 222 is the furthest from the first surface 223, the second groove 225 may also not intersect with the first groove closest to the first surface 223.

[0299] By setting the first groove 222 and the second groove 225 to a structure in which they do not contact each other, the mutual influence between the first groove 222 and the second groove 225 during the processing can be reduced. On the other hand, the phenomenon that the second weak part 228 will crack when the first weak part 221 cracks and releases pressure can be reduced. Furthermore, the stress influence between the first weak part 221 and the second weak part 228 can be reduced.

[0300] In embodiments where the first groove 222 includes multiple groove segments, a first weak segment 2211 is formed in the area corresponding to each groove segment. Exemplarily, the pressure relief component 22 is provided with the first groove 222, and the pressure relief component 22 forms a first weak segment 221 in the area where the first groove 222 is provided; the first groove 222 includes connected first groove segments 2221 and second groove segments 2222, the pressure relief component 22 forms a first weak segment 2211 in the area of ​​the first groove segment 2221, and the pressure relief component 22 forms a first weak segment 2211 in the area corresponding to the second groove segment 2222.

[0301] The first segment 2221 can extend in a straight line. The second segment 2222 can extend in a straight line. The first segment 2221 and the second segment 2222 together define at least one predetermined pressure relief region P, which is configured to be openable when the pressure relief component 22 cracks along at least part of the first weak point 221 to release the pressure inside the battery cell 20.

[0302] The first groove segment 2221 can also extend along the curve. The second groove segment 2222 can also extend along the curve.

[0303] The first slot segment 2221 and the second slot segment 2222 each form a first weak segment 2211, and the first weak portion 221 may include two first weak segments 2211. Since the first slot segment 2221 and the second slot segment 2222 are connected, the first weak segment 2211 formed in the region of the first slot segment 2221 and the first weak segment 2211 formed in the region of the second slot segment 2222 are connected, forming a first weak portion 221 including two connected first weak segments 2211. When one of the first weak segments 2211 begins to crack, it can drive the other first weak segment 2211 to crack, which is conducive to the rapid cracking of the first weak portion 221 to open the predetermined pressure relief zone P and achieve rapid pressure relief.

[0304] The first groove segment 2221 and the second groove segment 2222 together define the predetermined pressure relief area P. That is, the first groove segment 2221 and the second groove segment 2222 are structures that are set 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.

[0305] The predetermined pressure relief zone P is configured to be openable when the pressure relief component 22 cracks along at least part of the first weak portion 221. That is, when the battery cell 20 experiences thermal runaway and releases internal pressure, the area of ​​the pressure relief component 22 where the first groove 2221 and the second groove 2222 are provided can crack, thereby allowing the predetermined pressure relief zone P to be opened and releasing the internal pressure of the battery cell 20.

[0306] The connection between the first slot segment 2221 and the second slot segment 2222 can take many forms, such as forming a "T" shape, a "V" shape, an "L" shape, or an "X" shape.

[0307] The first groove 222 includes a first groove segment 2221 and a second groove segment 2222, and the first groove segment 2221 and the second groove segment 2222 are interconnected. On the one hand, it can increase the pressure relief area of ​​the battery cell 20 to improve the pressure relief rate of the battery cell 20. On the other hand, it makes the connection between the first groove segment 2221 and the second groove segment 2222 weaker, making it easier to crack and open the predetermined pressure relief area P to release the internal pressure of the battery cell 20.

[0308] like Figure 17 As shown, in some embodiments, the first groove 222 includes a third groove segment 2223, the first groove segment 2221 and the third groove segment 2223 are arranged opposite to each other, the second groove segment 2222 connects the first groove segment 2221 and the third groove segment 2223, and the pressure relief component 22 forms a first weak segment 2211 in the area corresponding to the third groove segment 2223.

[0309] The third segment 2223 can extend in a straight line. The first segment 2221, the second segment 2222 and the third segment 2223 together define a predetermined pressure relief area P, which is configured to be able to be opened when the pressure relief component 22 cracks along at least part of the first weak portion 221 to release the internal pressure of the battery cell 20.

[0310] The extension direction of the first slot segment 2221 is parallel to the extension direction of the third slot segment 2223, and the extension direction of the first slot segment 2221 is perpendicular to the extension direction of the second slot segment 2222. The extension direction of the third slot segment 2223 is perpendicular to the extension direction of the second slot segment 2222. That is, the first slot segment 2221 and the third slot segment 2223 are perpendicular to the second slot segment 2222.

[0311] The connection between the first slot segment 2221, the second slot segment 2222, and the third slot segment 2223 can take many forms. For example, the first slot segment 2221, the second slot segment 2222, and the third slot segment 2223 can be connected to form an "H" shape, or the first slot segment 2221, the second slot segment 2222, and the third slot segment 2223 can be connected to form a "U" shape.

[0312] Among them, the bottom wall of the first groove segment 2221, the bottom wall of the second groove segment 2222, and the bottom wall of the third groove segment 2223 all form the first weak segment 2211, that is, the first weak part 221 includes three first weak segments 2211, which are the bottom wall of the first groove segment 2221, the bottom wall of the second groove segment 2222, and the bottom wall of the third groove segment 2223, respectively. The three first weak segments 2211 constitute the first weak part 221.

[0313] The third slot segment 2223 forms a first weak segment 2211 in the corresponding area, so the first weak part 221 includes three first weak segments 2211. The second slot segment 2222 connects the first slot segment 2221 and the third slot segment 2223. The first weak segment 2211 formed in the corresponding area of ​​the second slot segment 2222 connects the first weak segment 2211 formed in the corresponding area of ​​the first slot segment 2221 and the first weak segment 2211 formed in the corresponding area of ​​the third slot segment 2223. When one of the first weak segments 2211 begins to crack, it can drive the other first weak segment 2211 to crack, which is conducive to the rapid cracking of the first weak part 221 to open the predetermined pressure relief zone P and achieve rapid pressure relief.

[0314] 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 arranged alternately. For example, in... Figure 17 In the first groove segment 2221 and the third groove segment 2223 are arranged at intervals along the length direction Y of the first wall portion, and both the first groove segment 2221 and the third groove segment 2223 extend along the width direction Z of the first wall portion.

[0315] The second slot segment 2222 connects the first slot segment 2221 and the third slot segment 2223. That is, the second slot segment 2222 is located between the first slot segment 2221 and the third slot segment 2223, and both ends of the second slot segment 2222 are connected to the first slot segment 2221 and the third slot segment 2223, respectively. For example, in... Figure 17 In this embodiment, the second groove segment 2222 extends along the length direction Y of the wall portion. Of course, in other embodiments, the second groove segment 2222 may also extend into a first groove segment 2221 and a third groove segment 2223 at both ends of the second groove segment 2222 along the length direction Y of the wall portion.

[0316] The first groove 222 is provided with a first groove segment 2221 and a third groove segment 2223 arranged opposite to each other, and a second groove segment 2222 connecting the first groove segment 2221 and the third groove segment 2223, so that the pressure relief component 22 can split along the first groove segment 2221, the second groove segment 2222 and the third groove segment 2223 when the battery cell 20 is depressurized, 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 this structure makes the intersection of the first groove segment 2221 and the second groove segment 2222 and the intersection of the second groove segment 2222 and the third groove segment 2223 weaker, making it 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.

[0317] like Figure 17 As shown, in some embodiments, the position where the second slot segment 2222 is connected to the first slot segment 2221 is offset from both ends of the first slot segment 2221, and the position where the second slot segment 2222 is connected to the third slot segment 2223 is offset from both ends of the third slot segment 2223.

[0318] The position where the second groove segment 2222 connects to the first groove segment 2221 is offset from both ends of the extension direction of the first groove segment 2221. The position where the second groove segment 2222 connects to the third groove segment 2223 is offset from both ends of the extension direction of the third groove segment 2223.

[0319] The connection position between the first groove segment 2221 and the second groove segment 2222 is offset from both ends of the first groove segment 2221. That is, the second groove segment 2222 is connected between the two ends of the first groove segment 2221. Similarly, the connection position between the third groove segment 2223 and the second groove segment 2222 is offset from both ends of the third groove segment 2223. That is, the second groove segment 2222 is connected between the two ends of the third groove segment 2223. This makes the shape of the first groove 222 formed by the first groove segment 2221, the second groove segment 2222 and the third groove segment 2223 approximately "H" shaped. A predetermined pressure relief area P is formed on both sides of the second groove segment 2222. Of course, the areas of the two predetermined pressure relief areas P can be the same or different.

[0320] For example, the second groove segment 2222 is a straight structure extending along the length direction Y of the first wall portion, the first groove segment 2221 and the third groove segment 2223 are both straight structures extending along the width direction Z of the first wall portion, and the second groove segment 2222 is located between the first groove segment 2221 and the third groove segment 2223 along the length direction Y of the first wall portion.

[0321] By setting the first groove segment 2221, the second groove segment 2222, and the third groove segment 2223 to extend along a straight trajectory, and setting the first groove segment 2221 and the third groove segment 2223 to be perpendicular to the second groove segment 2222, the extension direction of the second groove segment 2222 is the arrangement direction of the first groove segment 2221 and the third groove segment 2223. On the one hand, it can improve the regularity of the shape of the first groove 222, which is conducive to reducing the processing difficulty of the first groove 222 and thus 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 segment 2222 release pressure in opposite directions when the battery cell 20 is depressurized.

[0322] The second groove segment 2222 is connected to the first groove segment 2221 at a position offset from both ends of the first groove segment 2221. The connection position between the first groove segment 2221 and the second groove segment 2222 is set to be between the two ends of the first groove segment 2221. The second groove segment 2222 is connected to the third groove segment 2223 at a position offset from both ends of the third groove segment 2223. The connection position between the third groove segment 2223 and the second groove segment 2222 is set to be between the two ends of the third groove segment 2223. The first groove segment 2221, the second groove segment 2222, and the third groove segment 2223 form an H-shaped structure, so that a predetermined pressure relief area P can be formed on both sides of the second groove segment 2222 of the first groove 222. The two predetermined pressure relief areas P can be opened in a split manner to relieve pressure when the battery cell 20 is depressurized, 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.

[0323] The first groove 222 can also be other structures, see reference. Figure 9 The first groove 222 formed by the first groove segment 2221, the second groove segment 2222 and the third groove segment 2223 can be a "U" shaped structure, that is, one end of the second groove segment 2222 is connected to one end of the first groove segment 2221 and the other end is connected to one end of the third groove segment 2223, so as to form a predetermined pressure relief area P on the pressure relief component 22.

[0324] In some embodiments, the first groove 222 further includes a fourth groove segment 2224, which is disposed between the first groove segment 2221 and the third groove segment 2223. The fourth groove segment 2224 is connected to the third groove segment 2223, and the area corresponding to the fourth groove segment 2224 forms a first weak segment 2211.

[0325] For example, such as Figure 17 As shown, the fourth groove segment 2224 intersects the second groove segment 2222 perpendicularly. The fourth groove 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 groove segment 2224 is less than the length of the first groove segment 2221, and the length of the fourth groove segment 2224 is less than the length of the third groove segment 2223.

[0326] The bottom wall of the fourth segment 2224 forms a first weak segment 2211. The bottom walls of the first segment 2221, the second segment 2222, the third segment 2223, and the fourth segment 2224 together form a first weak part 221 including four first weak segments 2211.

[0327] The fourth groove segment 2224 is designed to facilitate the pressure relief component 22 to split from the intersection of the second groove segment 2222 and the fourth groove segment 2224, thereby enabling the two predetermined pressure relief zones P located on both sides of the second groove segment 2222 to open synchronously, thereby improving the pressure relief rate.

[0328] like Figure 17 As shown, in some embodiments, the first weak portion 221 defines two predetermined pressure relief zones P, which are located on both sides of the second groove segment 2222 respectively; the pressure relief component 22 also includes a second weak portion 228, which is configured to guide the predetermined pressure relief zone P to open, and at least one second weak portion 228 is provided for each predetermined pressure relief zone P.

[0329] Each predetermined pressure relief zone P can be provided with one second weak point 228, or multiple second weak points 228 can be provided.

[0330] Each second weak section 228 is configured to guide the corresponding predetermined pressure relief zone P to flip when the first weak section 221 cracks, thereby guiding the predetermined pressure relief zone P to open.

[0331] The second weak part 228 can guide the corresponding predetermined pressure relief zone P to open. Each predetermined pressure relief zone P is provided with at least one second weak part 228, thereby improving the opening effect of each predetermined pressure relief zone P of the pressure relief component 22. This is beneficial to increasing the pressure relief area of ​​the battery cell 20 after the predetermined pressure relief zone P is opened, thereby increasing the pressure relief rate of the battery cell 20 when thermal runaway occurs. This reduces the risk of fire, explosion, connection failure, etc. caused by untimely pressure relief of the battery cell 20, and helps to improve the reliability of the battery cell 20.

[0332] In some embodiments, each predetermined pressure relief zone P is provided with a second weak portion 228; 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.

[0333] The first weak part 221 defines two predetermined pressure relief areas P, and each predetermined pressure relief area P is provided with a corresponding second weak part 228. Then, the pressure relief component 22 is provided with two second grooves 225.

[0334] The extension direction of the second groove 225 is parallel to the extension direction of the second segment 2222 of the first groove 222. The two second grooves 225 are arranged at intervals along the extension direction of the first segment 2221 of the first groove 222. The first segment 2221 and the third segment 2223 of the first groove 222 are located between the two second grooves 225, and the second segment 2222 is located between the two second grooves 225, so that the first groove 222 is located between the two second grooves 225.

[0335] Each first groove 222 is located between the edge of the first wall portion 211 and the first groove 222 along the width direction Z of the first wall portion. Two second grooves 225 separate the edge of the first wall portion 211 from the first groove 222 on both sides of the first groove 222 along the width direction Z of the first wall portion.

[0336] The first groove 222 is located between the two second grooves 225, so that the second grooves 225 can also play a certain buffering role for the first groove 222. Thus, when the battery cell 20 is subjected to internal and external impact forces and deforms, the second grooves 225 can also absorb the deformation energy of the battery cell 20, so as to play a certain protective role for the area of ​​the pressure relief component 22 where the first groove 222 is provided. In this way, it can effectively reduce the deformation or damage of the area of ​​the pressure relief component 22 where the first groove 222 is provided when the battery cell 20 is subjected to internal and external impact forces, thereby alleviating the situation of premature pressure relief of the battery cell 20 during use.

[0337] In some embodiments, the second groove segment 2222 and the second groove 225 are disposed opposite to each other along a first direction, and along the first direction, the first groove segment 2221 and the third groove segment 2223 are both disposed at intervals from the second groove 225.

[0338] The second groove segment 2222 and the second groove 225 are arranged opposite to each other along the first direction. Along the first direction, the first groove segment 2221 and the third groove segment 2223 are all spaced apart from the second groove 225. Thus, the first groove segment 2221, the second groove segment 2222 and the third groove segment 2223 do not contact the second groove 225. This can reduce the mutual influence between the first groove 222 and the second groove 225 during the processing, reduce the phenomenon that the second weak part 228 will crack when the first weak part 221 cracks to release pressure, and reduce the stress influence between the first weak part 221 and the second weak part 228.

[0339] In some embodiments, the first wall portion 211 has a rectangular structure, and the first direction is parallel to the width direction Z of the first wall portion.

[0340] Specifically, the first groove segment 2221 and the third groove segment 2223 extend along the width direction Z of the first wall portion, and the second groove 225 and the second groove segment 2222 extend along the length direction Y of the first wall portion. The second groove 225 and the second groove segment 2222 are arranged at intervals relative to each other along the width direction Z of the first wall portion.

[0341] If the first direction is parallel to the width direction Z of the first wall portion, then the second groove segment 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 segment 2221 and the third groove segment 2223 are all spaced apart from the second groove 225. The first groove segment 2221, the second groove segment 2222 and the third groove segment 2223 do not contact 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, reduce the phenomenon that the second weak part 228 will crack when the first weak part 221 cracks and releases pressure, and reduce the stress influence between the first weak part 221 and the second weak part 228.

[0342] In some embodiments, see Figure 10 The pressure relief component 22 is integrally formed with the first wall portion 211. That is to say, the pressure relief component 22 and the first wall portion 211 are an integral structure. The pressure relief component 22 and the first weak part 221 are integrally formed on the first wall portion 211. In other words, the pressure relief component 22 is the first wall portion 211, so that the pressure relief component 22 is part of the outer shell 21.

[0343] For example, in Figure 10 In this configuration, the first wall portion 211 is the bottom wall of the housing 212, which is positioned opposite to the end cap 213 along the thickness direction X of the first wall portion. The pressure relief component 22 is the bottom wall, and a first groove 222 forming the first weak point 221 is provided on the bottom wall. If the first wall portion 211 is the end cap 213, then the pressure relief component 22 is the end cap 213, allowing the pressure relief component 22 to close the opening 2121 of the housing 212, and both electrode terminals 24 are mounted on the pressure relief component 22.

[0344] By making the pressure relief component 22 and the first wall portion 211 an integrally formed structure, the pressure relief component 22 is integrated into the first wall portion 211, that is, the pressure relief component 22 is a wall of the outer casing 21. Correspondingly, the pressure relief component 22 is provided on the first wall portion 211. The battery cell 20 with 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 caused by improper assembly between the pressure relief component 22 and the first wall portion 211.

[0345] In some embodiments, the pressure relief component 22 is made of aluminum alloy.

[0346] 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 aluminum alloy. If the first wall portion 211 is an end cap 213, the end cap 213 can be made of aluminum alloy; if the first wall portion 211 is a wall portion in the housing 212, then the housing 212 can be made of aluminum alloy.

[0347] Aluminum alloys are lightweight and have good ductility, making it easier to machine 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 forming difficulty of the first wall portion 211.

[0348] In some embodiments, the aluminum alloy comprises the following components in weight 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%.

[0349] This aluminum alloy belongs to the tri-series aluminum alloy. The aluminum alloy has lower hardness and better formability, which reduces the processing difficulty of the first groove 222, helps to improve the processing accuracy of the first groove 222, and improves the pressure relief consistency of the pressure relief component 22.

[0350] In some embodiments, the aluminum alloy comprises the following components by mass percentage: aluminum ≥ 96.7%, copper ≤ 0.05% ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other individual element components ≤ 0.05%, and other element total components ≤ 0.15%.

[0351] This aluminum alloy belongs to the five-series aluminum. Pressure relief components made from this aluminum alloy have higher hardness, greater strength, and better resistance to damage.

[0352] like Figure 4 As shown, in some embodiments, the pressure relief component 22 is separately disposed from the first wall portion 211, the first wall portion 211 is provided with a pressure relief hole, and the pressure relief component 22 is installed on the wall portion and covers the pressure relief hole.

[0353] The pressure relief hole extends through both sides of the thickness direction X of the first wall and is connected to the interior of the outer casing 21.

[0354] The pressure relief component 22 and the first wall portion 211 are separate components. Before assembly, the pressure relief component 22 and the first wall portion 211 are two separate parts. To complete the assembly, the pressure relief component 22 and the first wall portion 211 need to be connected as a whole through a connection. The pressure relief component 22 can be connected to the wall of the pressure relief hole and cover the pressure relief hole. Alternatively, the pressure relief component 22 is welded to the first wall portion 211.

[0355] By setting the pressure relief component 22 and the first wall portion 211 as separate components, the pressure relief component 22 is mounted on the first wall portion 211. The battery cell 20 with this structure can reduce the difficulty of setting the pressure relief component 22 on the first wall portion 211, and can make the processing steps of the outer casing 21 and the processing steps of the pressure relief component 22 be carried out simultaneously, which is beneficial to optimizing the production cycle of the battery cell 20.

[0356] like Figure 10 As shown, in some embodiments, the battery cell 20 includes an electrode assembly 23, which is housed within the housing 21, and a first wall portion 211 supports the electrode assembly 23.

[0357] The battery cell 20 may include one or more electrode assemblies 23. In embodiments where the battery cell 20 includes multiple electrode assemblies 23, the multiple electrode assemblies 23 are stacked along their thickness direction.

[0358] The first wall portion 211 supports the electrode assembly 23, and understandably, the first wall portion 211 bears the weight of the electrode assembly 23.

[0359] 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 that the substances released when the battery cell 20 is depressurized will act on other electrical connection structures, thereby reducing the risk of causing other reliability problems.

[0360] In some embodiments, the battery cell 20 includes an electrode terminal 24 disposed on the other walls of the housing 21, excluding the first wall portion 211.

[0361] The electrode terminal 24 is disposed on the other walls of the housing 21 except for the first wall portion 211. That is, the electrode terminal 24 and the pressure relief component 22 are disposed on different walls of the housing 21.

[0362] The electrode terminals 24 are located on the walls of the housing 21 other than the first wall portion 211. This reduces the risk that the substances released when the battery cell 20 is depressurized will act on the electrode terminals 24. This also reduces the risk that the battery cell 20 will short-circuit again and cause thermal runaway due to the substances released when the battery cell 20 is depressurized acting on the electrode terminals 24 to form an electrical connection.

[0363] In some embodiments, electrode terminals 24 are disposed on the wall of housing 21 opposite to the first wall portion 211.

[0364] The electrode terminal 24 is disposed on the wall of the housing 21 opposite to the first wall portion 211, so that the distance between the electrode terminal 24 and the pressure relief component 22 is greater, which can further reduce the risk that the substances released when the battery cell 20 is depressurized will act on the electrode terminal 24. This further reduces the risk that the battery cell 20 will short-circuit again and cause thermal runaway due to the interaction between the substances released when the battery cell 20 is depressurized and the electrode terminal 24 forming an electrical connection.

[0365] In some embodiments, the housing 21 includes a housing 212 and an end cap 213. The housing 212 has at least one opening 2121. The end cap 213 is provided in a one-to-one correspondence with the opening 2121. The end cap 213 is connected to the housing 212 and closes the opening 2121. At least the end cap 213 is a first wall portion 211.

[0366] End cap 213 is the first wall portion 211, that is, the pressure relief component 22 is disposed on end cap 213. In an embodiment where housing 212 has two opposing openings 2121, housing 21 includes two end caps 213. One end cap 213 may be the first wall, that is, one end cap 213 is provided with pressure relief component 22, or both end caps 213 may be the first wall, that is, both end caps 213 are provided with pressure relief component 22.

[0367] By setting the first wall portion 211 of the housing 21 as an end cap 213 for closing the opening 2121, the battery cell 20 with this structure is easy to install a pressure relief component 22 on the end cap 213, which helps to reduce the manufacturing difficulty of the battery cell 20 and improve the production efficiency of the battery cell 20.

[0368] 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, see [link to relevant documentation]. Figure 3 and Figure 4 As shown, the housing 21 may include a housing 212 and an end cap 213. The housing 212 has an internal cavity with an opening 2121 for accommodating the electrode assembly 23. The end cap 213 closes the opening 2121. The housing 212 includes a first wall portion 211.

[0369] The shell 212 may include integrally formed side walls and bottom walls, that is, the shell 212 is manufactured by integral forming process, such as stamping, casting or extrusion molding, etc. In other words, the side walls and bottom walls of the shell 212 are integral structures.

[0370] The housing 212 includes a first wall portion 211, that is, the first wall portion 211 is a wall in the housing 212. For example, in Figure 10 In this embodiment, the first wall portion 211 is the bottom wall of the housing 212 that is disposed opposite to 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.

[0371] By setting the first wall portion 211 of the outer casing 21 as a wall of the housing 212, the battery cell 20 with this structure can make the area of ​​the outer casing 21 where the pressure relief component 22 is provided far away from the end cap 213. This can effectively alleviate the stress generated by the connection between the end cap 213 and the housing 212 on the pressure relief component 22, thereby reducing the impact on the predetermined pressure relief area P and the first weak part 221 of the pressure relief component 22. This helps to reduce the risk of cracking or structural strength reduction of the pressure relief component 22 under the stress, thereby improving the service life and reliability of the battery cell 20.

[0372] It should be noted that the structure of the battery cell 20 can be varied. In some embodiments, the housing 212 has two openings 2121 arranged opposite to each other; the outer shell 21 includes two end caps 213, each end cap 213 is connected to the housing 212 and closes one opening 2121, and the housing 212 includes a first wall portion 211.

[0373] The housing 212 has an internal cavity, and two openings 2121 communicate with the cavity. The two openings 2121 can be arranged opposite each other along the thickness direction X of the first wall. In an embodiment where the housing 21 includes two openings 2121 and two end caps 213, the first wall 211 can also be a wall of the housing 212.

[0374] The housing 212 of the outer casing 21 has two openings 2121 arranged opposite to each other, and two end caps 213 respectively close the two openings 2121. The battery cell 20 with this structure is easy to assemble from both ends of the housing 212, which helps to reduce the manufacturing and assembly difficulty of the battery cell 20. The housing 212 includes a first wall portion 211. The pressure relief component 22 is not provided on the end caps 213, which can reduce the risk that the substances released when the battery cell 20 is depressurized will act on other structures of the battery 100. This further reduces the risk that the substances released when the battery cell 20 is depressurized will act on the electrode terminals 24 to form an electrical connection, causing a short circuit in the battery cell 20 and causing thermal runaway of the battery cell 20 again.

[0375] In an embodiment where the housing 21 includes two openings 2121 and two end caps 213, the two end caps 213 respectively close the two openings 2121, and one of the end caps 213 is a first wall portion 211. Of course, both end caps 213 can also be first wall portions 211, and each first wall portion 211 is provided with a pressure relief component 22.

[0376] In some embodiments, the housing 212 has an opening 2121, and the wall portion of the housing 212 opposite to the opening 2121 is a first wall portion 211.

[0377] For example, the wall portion of the housing 212 opposite to the opening 2121 is the bottom wall of the housing 212, the bottom wall is the first wall portion 211, the end cap 213 is disposed opposite to the first wall portion 211, and the electrode terminal 24 is disposed on the end cap 213.

[0378] The wall portion of the housing 212 that is disposed opposite to the opening 2121 is the first wall portion 211, which can reduce the risk that the substances released when the battery cell 20 is depressurized will act on other structures of the battery. This further reduces the risk that the battery cell 20 will short-circuit again and cause thermal runaway due to the substances released when the battery cell 20 is depressurized acting on the electrode terminal 24 to form an electrical connection.

[0379] In some embodiments, this application also provides a battery 100, which includes the battery cell 20 provided in any of the above embodiments.

[0380] Among them, see Figure 2 As shown, the battery 100 may also include a housing 10, in which the battery cells 20 are housed.

[0381] In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, the first housing body 11 and the second housing body 12 covering each other, the first housing body 11 and the second housing body 12 together defining an assembly space for accommodating the battery cell 20.

[0382] 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. 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 together define the 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.

[0383] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder or a cuboid. For example, in... Figure 2 In the middle, box 10 has a rectangular structure.

[0384] Optionally, the battery cell 20 disposed within the housing 10 can be one or more. For example, in... Figure 2 In this battery 100, multiple battery cells 20 are arranged inside the casing 10. These battery cells 20 can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that some of the battery cells 20 are connected in series and others in parallel. The multiple battery cells 20 can be directly connected in series, parallel, or in a mixed configuration, and then the entire assembly of the multiple battery cells 20 is housed inside the casing 10. Alternatively, the battery 100 can also be composed of multiple battery cells 20 first connected in series, parallel, or in a mixed configuration to form a battery 100 module, and then the multiple battery 100 modules are connected in series, parallel, or in a mixed configuration to form a whole, which is then housed inside the casing 10.

[0385] The battery 100 may also include other structures. For example, the battery 100 may also include a busbar component that connects multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20.

[0386] It should be noted that in some embodiments, the battery 100 may not have a housing 10. The battery 100 includes multiple battery cells 20, and the battery 100 composed of multiple battery cells 20 can be directly mounted onto an electrical device to provide power to the electrical device through the multiple battery cells 20. That is, the housing 10 can be part of the electrical equipment. Taking a vehicle 1000 as an example, the housing 10 can be part of the chassis structure of the vehicle 1000. For example, a portion of the housing 10 can be at least a part of the floor of the vehicle 1000, or a portion of the housing 10 can be at least a part of the crossbeams and longitudinal beams of the vehicle 1000.

[0387] In some embodiments, this application also provides an electrical device, which includes the battery cell 20 provided in any of the above embodiments.

[0388] The battery cell 20 is used to provide electrical energy to electrical equipment. The electrical equipment can be any of the aforementioned devices or systems that use the battery cell 20.

[0389] This 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, in which the electrode assembly 23 is received. The end cap 213 closes the opening 2121 and is the first wall portion 211. The pressure relief component 22 is separately disposed from the first wall portion 211.

[0390] 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 to each other. The first surface 223 is located on the side of the pressure relief component 22 facing away from the interior of the outer casing 21, and the second surface 224 is located on the side of the pressure relief component 22 facing the interior of the outer casing 21. The first surface 223 of the pressure relief component 22 is provided with three levels of grooves, which are arranged sequentially from the first surface 223 to the second surface 224. The first level groove furthest from the first surface 223 is a first groove 222, and the area corresponding to the first groove 222 forms a first weak portion 221. The first weak portion 221 defines at least one predetermined pressure relief area P. The pressure relief component 22 is configured to crack along at least a portion of the first weak portion 221 when the battery cell 20 is depressurized. The first weak portion 221 includes a plurality of first weak segments 2211. The second surface 224 is provided with a second groove 225, and the pressure relief component 22 forms a second weak part 228 in the area corresponding to the second groove 225. Along the thickness direction X of the first wall, the thickness of the second weak part 228 is greater than the thickness of the first weak part 221. The second weak part 228 is configured to guide the predetermined pressure relief area P to flip when the first weak part 221 cracks, so as to release the internal pressure of the battery cell 20.

[0391] The first groove 222 includes a first groove segment 2221, a second groove segment 2222, a third groove segment 2223, and a fourth groove segment 2224. Each of these segments forms a first weak section 2211. Along the length Y direction of the first wall portion, the first groove segment 2221 and the third groove segment 2223 are arranged at intervals. Both the first groove segment 2221 and the third groove segment 2223 extend linearly along the width Z direction of the first wall portion. The third groove segment 2223 extends linearly along the length Y direction of the first wall portion. The second groove segment 2222 connects the first groove segment 2221 and the third groove segment 2223. The connection point between the second groove segment 2222 and the first groove segment 2221 is located between the two ends of the first groove segment 2221, and the connection point between the second groove segment 2222 and the third groove segment 2223 is located between the two ends of the third groove segment 2223. The first groove segment 2221, the second groove segment 2222, and the third groove segment 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 each side of the second groove segment 2222. The first weak portion 221 defines two predetermined pressure relief zones P. A fourth groove segment 2224 is located between the first groove segment 2221 and the third groove segment 2223, and intersects with the second groove segment 2222.

[0392] The sum of the areas of all predetermined pressure relief zones P is S, and the area of ​​the cross-section of the first weak segment 2211 perpendicular to its extension direction is S1, satisfying: 300mm 2 ≤S≤1500mm 20.006mm 2 ≤S1≤0.15mm 2 Preferably, 400mm 2 ≤S≤1200mm 2 0.01mm 2 ≤S1≤0.1mm 2 The width of the bottom surface of the groove segment is A, and the thickness of the first weak segment 2211 is H, satisfying: S1=A×H; 0.1mm≤A≤0.3mm, 0.06mm≤H≤0.5mm; preferably, 0.15mm≤A≤0.25mm, 0.1mm≤H≤0.3mm.

[0393] According to some embodiments of this application, see Figures 3 to 4 As shown, this 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, in which the electrode assembly 23 is received. The end cap 213 closes the opening 2121. The bottom wall of the shell 212, which is opposite to the end cap 213 in the thickness direction X, is the first wall portion 211. The pressure relief component 22 is integrally formed with the first wall portion 211, that is, the pressure relief component 22 is the first wall portion 211 of the housing 21.

[0394] 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 to each other. The first surface 223 is located on the side of the pressure relief component 22 facing away from the interior of the outer casing 21, and the second surface 224 is located on the side of the pressure relief component 22 facing the interior of the outer casing 21. The first surface 223 of the pressure relief component 22 is provided with three levels of grooves, which are arranged sequentially from the first surface 223 to the second surface 224. The first level groove furthest from the first surface 223 is a first groove 222, and the area corresponding to the first groove 222 forms a first weak portion 221. The first weak portion 221 defines at least one predetermined pressure relief area P. The pressure relief component 22 is configured to crack along at least a portion of the first weak portion 221 when the battery cell 20 is depressurized. The first weak portion 221 includes a plurality of first weak segments 2211. The second surface 224 is provided with a second groove 225, and the pressure relief component 22 forms a second weak part 228 in the area corresponding to the second groove 225. Along the thickness direction X of the first wall, the thickness of the second weak part 228 is greater than the thickness of the first weak part 221. The second weak part 228 is configured to guide the predetermined pressure relief area P to flip when the first weak part 221 cracks, so as to release the internal pressure of the battery cell 20.

[0395] The first groove 222 includes a first groove segment 2221, a second groove segment 2222, a third groove segment 2223, and a fourth groove segment 2224. Each of these segments forms a first weak section 2211. Along the length Y direction of the first wall portion, the first groove segment 2221 and the third groove segment 2223 are arranged at intervals. Both the first groove segment 2221 and the third groove segment 2223 extend linearly along the width Z direction of the first wall portion. The third groove segment 2223 extends linearly along the length Y direction of the first wall portion. The second groove segment 2222 connects the first groove segment 2221 and the third groove segment 2223. The connection point between the second groove segment 2222 and the first groove segment 2221 is located between the two ends of the first groove segment 2221, and the connection point between the second groove segment 2222 and the third groove segment 2223 is located between the two ends of the third groove segment 2223. The first groove segment 2221, the second groove segment 2222, and the third groove segment 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 each side of the second groove segment 2222. The first weak portion 221 defines two predetermined pressure relief zones P. A fourth groove segment 2224 is located between the first groove segment 2221 and the third groove segment 2223, and intersects with the second groove segment 2222.

[0396] The sum of the areas of all predetermined pressure relief zones P is S, and the area of ​​the cross-section of the first weak segment 2211 perpendicular to its extension direction is S1, satisfying: 300mm 2 ≤S≤1500mm 2 0.006mm 2 ≤S1≤0.15mm 2 Preferably, 400mm 2 ≤S≤1200mm 2 0.01mm 2 ≤S1≤0.1mm 2 The width of the bottom surface of the groove segment of the first groove 222 is A, and the thickness of the first weak segment 2211 is H, satisfying: S1=A×H; 0.1mm≤A≤0.3mm, 0.06mm≤H≤0.5mm; preferably, 0.15mm≤A≤0.25mm, 0.1mm≤H≤0.3mm.

[0397] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized in that, include: The outer casing includes a first wall portion; A pressure relief component is disposed on the first wall portion, the pressure relief component includes a first weak portion, the first weak portion defining at least one predetermined pressure relief area, and the pressure relief component is configured to be able to split along at least a portion of the first weak portion when the battery cell is depressurized. Wherein, the sum of the areas of all the predetermined pressure relief zones is S, the first weak part includes at least one first weak segment, and the area of ​​the cross-section of the first weak segment perpendicular to its extension direction is S1, satisfying: 300mm 2 ≤S≤1500mm 2 0.006mm 2 ≤S1≤0.15mm 2 .

2. The battery cell according to claim 1, characterized in that, 400mm 2 ≤S≤1200mm 2 ,0.01mm 2 ≤S1≤0.1mm 2 。 3. The battery cell according to claim 1, characterized in that, The pressure relief component is provided with a first groove, the first groove includes at least one groove segment, the pressure relief component forms at least one first weak segment in the area where the groove segment is provided, the width of the bottom surface of the groove segment is A, and the thickness of the first weak segment is H, satisfying: S1=A×H; 0.1mm≤A≤0.3mm, 0.06mm≤H≤0.5mm.

4. The battery cell according to claim 3, characterized in that, 0.15mm≤A≤0.25mm, 0.1mm≤H≤0.3mm.

5. The battery cell according to claim 3, characterized in that, The pressure relief component has a first surface and a second surface that are arranged opposite to each other in the thickness direction of the first wall portion. The first groove is a multi-level groove. The multi-level grooves are arranged sequentially along the direction from the first surface to the second surface. In two adjacent levels of grooves, the first-level groove that is away from the first surface is located on the bottom surface of the first-level groove that is close to the first surface.

6. The battery cell according to claim 5, characterized in that, The first groove includes three levels of grooves, which are arranged sequentially along the direction from the first surface to the second surface.

7. The battery cell according to any one of claims 3-6, characterized in that, The pressure relief component also includes a second weak portion configured to guide the predetermined pressure relief zone to open.

8. The battery cell according to claim 7, characterized in that, The pressure relief component is provided with a second groove, and the pressure relief component forms a second weak part in the area where the second groove is provided.

9. The battery cell according to claim 8, characterized in that, The second groove is provided on the surface of the pressure relief component facing the inside of the housing.

10. The battery cell according to any one of claims 1-6, characterized in that, The pressure relief component has a first surface and a second surface disposed 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 a 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 a second weak portion in the area where the second groove is provided.

11. The battery cell according to claim 10, characterized in that, The first surface is the surface of the pressure relief component that faces away from the inside of the housing, and the second surface is the surface of the pressure relief component that faces the inside of the housing.

12. The battery cell according to claim 8, characterized in that, Along the thickness direction of the first wall portion, the projection of the first groove does not contact the projection of the second groove.

13. The battery cell according to any one of claims 1-6, characterized in that, The pressure relief component is provided with a first groove, and the pressure relief component forms the first weak part in the area where the first groove is provided; The first groove includes a first groove segment and a second groove segment connected together. The pressure relief component forms a first weak segment in the region of the first groove segment and a first weak segment in the region corresponding to the second groove segment.

14. The battery cell according to claim 13, characterized in that, The first groove includes a third groove segment, the first groove segment and the third groove segment are disposed 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.

15. The battery cell according to claim 14, characterized in that, The second groove segment is located at a position where it connects to the first groove segment, which is offset from both ends of the first groove segment. The second groove segment is located at a position where it connects to the third groove segment, which is offset from both ends of the third groove segment.

16. The battery cell according to claim 14, characterized in that, The first weak section defines two predetermined pressure relief zones, which are located on both sides of the second groove section, respectively. The pressure relief component further includes a second weak portion, which is configured to guide the opening of the predetermined pressure relief zone, and at least one second weak portion is provided for each predetermined pressure relief zone.

17. The battery cell according to claim 16, characterized in that, Each of the predetermined pressure relief zones is provided with a corresponding second weak point; The pressure relief component is provided with a second groove, and the pressure relief component forms a second weak part in the area where the second groove is provided, and the first groove is located between the two second grooves.

18. The battery cell according to claim 17, characterized in that, The second groove segment and the second recess are arranged opposite each other along the first direction. Along the first direction, the first groove segment and the third groove segment are both spaced apart from the second recess.

19. The battery cell according to claim 18, characterized in that, The first wall portion has a rectangular structure, and the first direction is parallel to the width direction of the first wall portion.

20. The battery cell according to any one of claims 1-6, characterized in that, The pressure relief component is integrally formed with the first wall portion.

21. The battery cell according to any one of claims 1-6, characterized in that, The pressure relief component is separately disposed 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 first wall portion and covers the pressure relief hole.

22. The battery cell according to any one of claims 1-6, characterized in that, The battery cell includes an electrode assembly, which is housed within the housing, and the first wall supports the electrode assembly.

23. The battery cell according to any one of claims 1-6, characterized in that, The battery cell includes electrode terminals, which are disposed on other walls of the housing other than the first wall.

24. The battery cell according to claim 23, characterized in that, The electrode terminals are disposed on the wall portion of the housing opposite to the first wall portion.

25. The battery cell according to any one of claims 1-6, characterized in that, The outer casing includes: The housing has at least one opening; End caps, each corresponding to one of the openings, are connected to the housing and close the openings; Wherein, at least one of the end caps is the first wall portion, or the housing includes the first wall portion.

26. The battery cell according to claim 25, characterized in that, The housing has two openings arranged opposite each other; the outer shell includes two end caps, each end cap being connected to the housing and closing one of the openings, and the housing includes the first wall portion.

27. The battery cell according to claim 25, characterized in that, The housing has an opening, and the wall portion of the housing opposite to the opening is the first wall portion.

28. The battery cell according to any one of claims 1-6, characterized in that, The pressure relief component is made of steel.

29. The battery cell according to claim 28, characterized in that, The steel material is carbon steel or stainless steel.

30. A battery, characterized in that, Includes the battery cell according to any one of claims 1-29.

31. An electrical appliance, characterized in that, Includes the battery cell according to any one of claims 1-29.

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