Battery cell, battery, and electrical apparatus

Abstract

A battery cell (200), a battery (400), and an electrical apparatus (500). The battery cell (200) comprises an electrode assembly (300), a housing (60), and a pressure relief part (40). The electrode assembly (300) comprises a positive pole piece and a negative pole piece. The positive pole piece and the negative pole piece are stacked to form a straight flat region (301). The housing (60) is used for accommodating the electrode assembly (300), wherein the housing (60) comprises a first wall part (11) and two second wall parts (12). The two second wall parts (12) are respectively located on two sides of the straight flat region (301). The pressure relief part (40) is arranged on the first wall part (11), and the pressure relief part (40) is formed with a score groove (41). First weak sections (42) and second weak sections (43) are formed at the bottom of the score groove (41), and the thickness of the second weak sections (43) is less than the thickness of the first weak sections (42).

Description

Battery cells, batteries, and electrical devices Technical Field

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

[0002] In the related art, a battery cell includes a shell and an electrode assembly. The electrode assembly is arranged in the shell, and the shell is provided with a pressure relief portion. When the battery cell expands, the large surface of the shell is deformed. The deformation of the large surface of the shell will pull the shell wall of the shell where the pressure relief portion is provided, causing the shell wall of the shell where the pressure relief portion is provided to deform, thereby subjecting the pressure relief portion to a pulling force, which can easily cause damage to the pressure relief portion and affect the normal use of the pressure relief portion.

[0003] Summary of the Invention

[0004] This application aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of this application is to provide a battery cell that can improve the deformation resistance of the notched groove. When the battery cell expands and causes the shell to deform, the impact of the shell deformation on the pressure relief portion can be reduced, thereby reducing the risk of damage to the pressure relief portion.

[0005] The present application further proposes a battery.

[0006] The present application further proposes an electrical device.

[0007] In a first aspect, an embodiment of the present application provides a battery cell, comprising:

[0008] An electrode assembly comprising a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet and the negative electrode sheet are stacked to form a flat region, and at least a portion of the positive electrode sheet and at least a portion of the negative electrode sheet are stacked along a first direction in the flat region;

[0009] a housing for accommodating the electrode assembly, the housing comprising a first wall portion and two second wall portions connected to the first wall portion, the two second wall portions being located on both sides of the flat area along the first direction;

[0010] A pressure relief portion is provided on the first wall portion, and a notched groove is formed on the pressure relief portion. A first weak section and a second weak section are formed at the bottom of the notched groove. The thickness of the second weak section is less than that of the first weak section. The first weak section is a straight section extending along a second direction, and the second direction is perpendicular to the first direction.

[0011] In the above technical solution, by making the thickness of the second weak section smaller than that of the first weak section and the first weak section extending along the second direction, the structural strength of the pressure relief part can be improved, the deformation resistance of the notched groove can be improved, and the influence of external force or deformation on the position of the notched groove of the pressure relief part can be reduced. When the battery cell expands and causes the shell to deform, the influence of the shell deformation on the pressure relief part can be reduced, thereby reducing the risk of damage to the pressure relief part, which is conducive to maintaining the normal use of the pressure relief part.

[0012] In some embodiments, the pressure relief portion is configured to rupture at the second weakened section when the internal pressure or temperature of the housing reaches a threshold value.

[0013] In the above technical solution, by configuring the pressure relief portion to crack at the second weak section, when the internal pressure or temperature of the shell reaches a threshold value, the bottom wall of the scored groove preferentially cracks at the second weak section under the action of the internal pressure of the shell, tearing the bottom wall of the scored groove. When thermal runaway occurs in the battery cell, it can crack from the second weak section and the first weak section, and during the normal use of the battery cell, the reliability of the scored groove can be improved and the risk of the scored groove rupture can be reduced.

[0014] In some embodiments, the scoring groove includes a first straight groove segment extending along the second direction, and the first weak segment is formed at the bottom of the first straight groove segment.

[0015] In the above technical solution, a first weak section is formed at the bottom of the first straight groove section, which can improve the deformation resistance of the first straight groove section, reduce the influence of external force or deformation on the position of the first straight groove section of the pressure relief part, and thus make the first weak section set at an appropriate position.

[0016] In some embodiments, the length dimension of the first weakened section is smaller than the length dimension of the first straight slot section.

[0017] In the above technical solution, by making the length dimension of the first weak section smaller than the length dimension of the first straight groove section, the thickness of the local position of the bottom wall of the first straight groove section can be thickened. On the basis of improving the deformation resistance of the notched groove, when the pressure in the installation cavity reaches a certain pressure, the notched groove can be smoothly torn open to achieve a pressure relief effect, thereby reducing the risk of the notched groove failing to open when the pressure in the installation cavity reaches a certain pressure, and improving the safety of battery cell use.

[0018] In some embodiments, the ratio of the length dimension of the first weak section to the length dimension of the first straight slot section is greater than or equal to 0.5 and less than or equal to 0.9.

[0019] In the above technical solution, by making the ratio of the length dimension of the first weak section to the length dimension of the first straight groove section greater than or equal to 0.5 and less than or equal to 0.9, the length dimension ratio of the first weak section formed in the first straight groove section can be appropriate. On the basis of better improving the deformation resistance of the notched groove, when the pressure in the installation cavity reaches a certain pressure, the notched groove can be quickly torn open smoothly to achieve a rapid pressure relief effect.

[0020] In some embodiments, along the second direction, the first weak section is located in the middle of the first straight slot section.

[0021] In the above technical solution, by arranging the first weak section in the middle of the first straight groove section, the structural reinforcement section can be arranged at a relatively large force position of the notched groove, which is more conducive to improving the deformation resistance of the notched groove, thereby making the arrangement position of the first weak section reasonable.

[0022] In some embodiments, the first weak section is symmetrical about a mid-section of the first straight slot section, and the mid-section is perpendicular to the second direction.

[0023] In the above technical solution, the first weak section is symmetrical about the mid-section of the first straight groove section, so the first weak section can be set at the center position of the first straight groove section. After the pressure relief portion is installed on the first wall portion, the first straight groove section corresponds to the second wall portion, so that the first weak section can be arranged at a position of the notched groove where the force is relatively large, so that the first straight groove section can be evenly stressed, further improving the structural strength of the notched groove, and being more conducive to improving the deformation resistance of the notched groove, thereby making the arrangement position of the first weak section reasonable.

[0024] In some embodiments, along the depth direction of the scoring groove, a difference between a thickness dimension of the second weak section and a thickness dimension of the first weak section is greater than 0.05 and less than or equal to 0.45 mm.

[0025] In the above technical solution, by making the difference between the thickness dimension of the second weak section and the thickness dimension of the first weak section greater than 0.05 and less than or equal to 0.45 mm, the thickness dimension of the first weak section can be made appropriate, that is, the deformation resistance of the notched groove can be improved, and when the pressure in the installation cavity reaches a certain pressure, the notched groove can also be torn open smoothly.

[0026] In some embodiments, the scoring groove includes two first straight groove segments extending along the second direction, and the first weak segment is formed at the bottom of each of the first straight groove segments.

[0027] In the above technical solution, two first straight groove sections extend in the second direction, and the bottom wall of each first straight groove section is formed with a first weak section. When the electrode assembly expands, the electrode assembly pushes against the second wall portion and pushes it outward, causing the outer shell to deform. When the second wall portion deforms, the deformation of the second wall portion pulls the first wall portion, causing the first wall portion to deform. The middle position of the second wall portion deforms the most, causing the middle position of the first wall portion to be subjected to the greatest pulling force. When the pressure relief portion is installed on the first wall portion, the two first straight groove sections extend in the second direction and are arranged in the first direction. The bottom of each first straight groove section is formed with a first weak section, which can enable the portion of the scored groove formed with the first weak section to be arranged corresponding to the second wall portion. When the first wall portion deforms, the force can be applied to the portion of the scored groove formed with the first weak section, which is beneficial to improving the deformation resistance of the scored groove.

[0028] In some embodiments, the two first weak sections include a first section and a second section, the thickness of the first section is smaller than the thickness of the second section, and the pressure relief portion is configured so that when the internal pressure or temperature of the housing reaches a threshold, the first section completely ruptures and at least a portion of the second section does not rupture.

[0029] In the above technical solution, the thickness of the first section is smaller than that of the second section, and the pressure relief portion is configured so that when the internal pressure or temperature of the shell reaches a threshold value, the first section completely ruptures, and at least a portion of the second section does not rupture, thereby achieving a pressure relief effect on the battery cell and reducing the risk of the pressure relief portion detaching from the battery cell.

[0030] In some embodiments, the two first weakened sections are of equal length.

[0031] In the above technical solution, by making the lengths of the two first weak sections equal, when the electrode assembly expands, the force on the notched groove can be evenly distributed, thereby further improving the deformation resistance of the notched groove and reducing the risk of tearing at the notched groove position of the pressure relief part, thereby further reducing the impact of the shell deformation on the pressure relief part.

[0032] In some embodiments, the scoring groove includes two first arcuate groove segments, and both ends of each first straight groove segment are respectively connected to two first arcuate groove segments to make the scoring groove structure annular, and the bottom of the first arcuate groove segment is formed with the second weak section.

[0033] In the above technical solution, the notched groove is constructed into a ring shape, and a second weak section is formed on the bottom wall of the first arcuate groove section. When the internal pressure or temperature of the shell reaches a threshold value, the second weak section of the bottom wall of the first arcuate groove section is cracked, which is conducive to the tearing and pressure relief of the notched groove, and can achieve the pressure relief effect on the battery cell, and can also reduce the risk of the pressure relief portion flying out of the battery cell, reducing the risk of the pressure relief portion flying out of the battery cell to personal safety.

[0034] In some embodiments, the scoring groove includes a first straight groove segment extending along the second direction, and the first weak segment is formed at the bottom of the first straight groove segment.

[0035] In the above technical solution, the notched groove includes a first straight groove segment, and a first weak segment is formed at the bottom of the first straight groove segment, so that the portion of the notched groove formed with the first weak segment can be arranged corresponding to the second wall portion. When the first wall portion is deformed, the force can be applied to the portion of the notched groove formed with the first weak segment, which is beneficial to improving the deformation resistance of the notched groove.

[0036] In some embodiments, the scoring groove includes one first straight groove segment and four second straight groove segments, two ends of the first straight groove segment are respectively connected to two second straight groove segments arranged at a preset angle, and the bottom of the second straight groove segment is formed with the second weak section; or,

[0037] The scoring groove includes one first straight groove segment and two third straight groove segments. The two ends of the first straight groove segment are respectively connected to the third straight groove segments, and the third straight groove segments are perpendicular to the first straight groove segment. The bottom of the third straight groove segment is formed with the second weak segment.

[0038] In the above technical solution, the scored groove includes a first straight groove segment and four second straight groove segments, and the bottom wall of the third straight groove segment is formed with a second weak section. This allows the two ends of the scored groove to form a double Y-shaped scored groove. When the pressure in the installation cavity reaches a certain pressure or the temperature reaches a threshold, the pressure inside the installation cavity can be released from the double Y-shaped scored groove, thereby quickly releasing pressure from the battery cell. In addition, the scored groove includes a first straight groove segment and two third straight groove segments, allowing the scored groove to be constructed into an "I" shape. The bottom wall of the third straight groove segment is formed with a second weak section. When the pressure in the installation cavity reaches a certain pressure or the temperature reaches a threshold, the first straight groove segment and the two third straight groove segments can be torn open, allowing the pressure inside the installation cavity to be released from the first straight groove segment and the third straight groove segment, thereby increasing the pressure release rate of the battery cell.

[0039] In some embodiments, along the second direction, a center of the pressure relief portion and a center of the first wall portion are offset.

[0040] In the above technical solution, by staggering the center of the pressure relief portion and the center of the first wall portion along the second direction, the pressure relief portion deviates from the center of the first wall portion. When the battery cell expands and causes the shell to deform, the pulling force on the pressure relief portion can be reduced, thereby reducing the impact of the shell deformation on the notch groove of the pressure relief portion, thereby reducing the risk of damage to the pressure relief portion, and facilitating the normal use of the explosion-proof portion.

[0041] In some embodiments, along the second direction, the length dimension of the pressure relief portion is D, the distance between the center of the pressure relief portion and the center of the first wall portion is L, and the length of the first wall portion is E, satisfying the relational expression: D / 2 < L < (E / 2 - D / 2) - 2.

[0042] In the above technical solution, through D / 2 < L < (E / 2 - D / 2) - 2, the distance between the center of the pressure relief portion and the center of the first wall portion along the second direction can be made appropriate. When the electrode assembly expands and causes the second wall portion of the outer shell to deform, on the basis of reducing the pulling force received by the pressure relief portion, the pressure relief portion can be smoothly opened, achieving the pressure relief effect, reducing the risk of explosion of the battery cell, and improving the safety of using the battery cell.

[0043] In some embodiments, the pressure relief portion and the first wall portion are integrally formed; or,

[0044] The pressure relief portion and the first wall portion are separately provided. The first wall portion is provided with a through hole, and the pressure relief portion is installed in the through hole.

[0045] In the above technical solution, by integrally forming the pressure relief portion and the first wall portion, the forming method of the pressure relief portion is simple, the number of components of the battery cell can be reduced, the structure of the battery cell can be simplified, and the manufacturing cost of the battery cell can also be reduced. In addition, by constructing the pressure relief portion and the first wall portion as separate components, it is convenient to set the pressure relief portion on the outer shell, with low production difficulty and high efficiency, and the production efficiency of the battery cell can be improved.

[0046] In some embodiments, the outer shell includes: a housing and an end cap. At least one side of the housing has an opening. The end cap is connected to the housing and is used to close the opening. The first wall portion is formed on the housing.

[0047] In the above technical solution, by forming the first wall portion on the housing, the structure of the end cap can be simplified, and at the same time, it is convenient to shorten the distance between the pressure relief portion and the main body portion of the electrode assembly. Furthermore, the path for the discharged medium to flow to the pressure relief portion during pressure relief can be shortened, the time for the discharged medium to reach the pressure relief portion can be shortened, the pressure relief timeliness of the battery cell is improved, and thus the reliability of the battery cell is effectively improved.

[0048] In some embodiments, both opposite sides of the housing have openings, and the two end caps are used to close the openings on the corresponding sides.

[0049] In the above technical solution, by having openings on both opposite sides of the housing and using the two end caps to close the openings on the corresponding sides, an installation cavity can be jointly defined, and at the same time, it is convenient for the manufacturing and forming of the housing, and it is also convenient for the electrode assembly to lead out the electrode tabs from both ends.

[0050] In some embodiments, the end cap is provided with an electrical connection portion, and the electrical connection portion is electrically connected to the positive electrode plate, or the electrical connection portion is electrically connected to the negative electrode plate.

[0051] In the above technical solution, the electrical energy of the battery cell can be input or output by electrically connecting the electrical connection portion to the positive electrode plate, or electrically connecting the electrical connection portion to the negative electrode plate.

[0052] In some embodiments, the first wall portion is used to support the electrode assembly and is located below the electrode assembly.

[0053] In the above technical solution, the electrode assembly is supported by the first wall portion, so that the electrode assembly can be stably installed in the installation cavity of the shell.

[0054] In some embodiments, the material of the housing includes at least one of aluminum, nickel-plated carbon steel, stainless steel, magnesium alloy, nickel alloy, copper alloy, and zirconium alloy.

[0055] In the above technical solution, the material of the shell includes at least one of aluminum, nickel-plated carbon steel, stainless steel, magnesium alloy, nickel alloy, copper alloy and zirconium alloy, which can improve the structural strength of the shell and also help reduce the manufacturing cost of the shell.

[0056] In some embodiments, the positive electrode plate includes a positive electrode current collector and the positive electrode active material region disposed on the surface of the positive electrode current collector, and the constituent material of the positive electrode current collector includes aluminum element with a mass percentage greater than or equal to 50%.

[0057] In the above technical solution, since the constituent material of the positive electrode current collector includes aluminum element with a mass percentage greater than or equal to 50%, compared with the composite current collector in the prior art, the manufacturing difficulty of the positive electrode plate can be reduced, and the manufacturing cost can be reduced.

[0058] In some embodiments, the tensile strength of the first wall portion is not less than 400 MPa.

[0059] In the above technical solution, the tensile strength of the shell is improved by ensuring that the tensile strength of the first wall is not less than 400 MPa, thereby reducing the deformation of the shell when the electrode assembly expands, thereby reducing the pulling on the surface where the pressure relief portion is located, reducing the probability of the shell or the pressure relief portion being pulled and broken, reducing the risk of leakage, and improving the reliability of the battery cell.

[0060] In a second aspect, an embodiment of the present application further provides a battery comprising the above-mentioned battery cell.

[0061] In a third aspect, an embodiment of the present application further provides an electrical device comprising the above-mentioned battery.

[0062] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] FIG1 is a schematic diagram of an electrical device according to an embodiment of the present application;

[0064] FIG2 is an exploded view of a battery according to an embodiment of the present application;

[0065] FIG3 is an exploded view of a battery cell according to the first embodiment of the present application;

[0066] FIG4 is a schematic diagram of a battery cell according to a second embodiment of the present application;

[0067] Figure 5 is an enlarged view of point A in Figure 4;

[0068] FIG6 is a schematic diagram of a battery cell according to a third embodiment of the present application;

[0069] FIG7 is an exploded view of a battery cell according to a second embodiment of the present application;

[0070] FIG8 is a schematic diagram of a first embodiment of a pressure relief portion of a battery cell according to an embodiment of the present application;

[0071] FIG9 is a front view of a first embodiment of a pressure relief portion of a battery cell according to an embodiment of the present application;

[0072] FIG10 is an enlarged view of the BB portion in FIG9 ;

[0073] Figure 11 is an enlarged view of point C in Figure 10;

[0074] FIG12 is a schematic diagram of a second embodiment of a pressure relief portion of a battery cell according to an embodiment of the present application;

[0075] FIG13 is a schematic diagram of a third embodiment of a pressure relief portion of a battery cell according to an embodiment of the present application;

[0076] FIG14 is a schematic diagram of a battery cell according to a fourth embodiment of the present application;

[0077] FIG15 is a schematic diagram of the assembly of the first wall portion and the pressure relief portion according to the present application. DETAILED DESCRIPTION

[0078] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0079] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0080] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0081] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0082] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0083] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0084] The term "plurality" used in this application refers to two or more (including two).

[0085] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0086] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0087] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel or in hybrid through a busbar.

[0088] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0089] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0090] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0091] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0092] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, the safety performance of the battery also needs to be considered.

[0093] In a battery cell, to ensure the safety performance of the battery cell, a pressure relief portion may be provided on the outer shell of the battery cell. When the battery cell experiences thermal runaway, the pressure inside the battery cell is released through the pressure relief portion to improve the safety of the battery cell.

[0094] During the charging and discharging process of the battery cell, the electrode assembly will expand hard, causing the shell to swell and deform, and the pressure relief part is arranged on the shell, especially some pressure relief parts are arranged on the wall on the side closer to the electrode assembly. The expansion of the electrode assembly will cause the wall where the pressure relief part is located to deform, thereby pulling the notch of the pressure relief part, causing the pressure relief part to be damaged at the notch and then leaking, etc. As a result, the pressure inside the battery cell will be destroyed before it reaches the detonation pressure of the pressure relief part, causing the pressure relief part to fail and the reliability of the pressure relief part to be low.

[0095] In view of this, an embodiment of the present application provides a battery cell, including an electrode assembly and a shell, the shell is used to accommodate the electrode assembly, the shell includes a first wall portion and two second wall portions connected to the first wall portion, the pressure relief portion is arranged on the first wall portion, the pressure relief portion is formed with a notched groove, the bottom of the notched groove is formed with a first weak section and a second weak section, the thickness of the second weak section is less than the thickness of the first weak section, and the first weak section is a straight section.

[0096] In such a battery cell, by making the thickness of the second weak section smaller than that of the first weak section and extending the first weak section along the second direction, the structural strength of the pressure relief part can be improved, the deformation resistance of the notched groove can be improved, and the influence of external force or deformation on the position of the notched groove of the pressure relief part can be reduced. When the battery cell expands and causes the shell to deform, the influence of the shell deformation on the pressure relief part can be reduced, thereby reducing the risk of damage to the pressure relief part, which is conducive to maintaining the normal use of the pressure relief part.

[0097] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0098] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0099] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0100] Please refer to Figure 1, which is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application. A battery 400 is disposed within the vehicle, and battery 400 may be located at the bottom, front, or rear of the vehicle. Battery 400 may be used to power the vehicle, for example, as the vehicle's operating power source.

[0101] The vehicle may further include a controller 600 and a motor 700 . The controller 600 is used to control the battery 400 to supply power to the motor 700 , for example, to meet the vehicle's power requirements for starting, navigating, and driving.

[0102] In some embodiments of the present application, the battery 400 can serve not only as the operating power source of the vehicle, but also as the driving power source of the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0103] Please refer to Figure 2, which is an exploded view of a battery 400 provided in some embodiments of the present application. The battery 400 includes a battery cell 200 and a box 401, wherein the box 401 is used to accommodate the battery cell 200.

[0104] The housing 401 is a component that houses the battery cells 200 and provides storage space for the battery cells 200. The housing 401 can have various structures. In some embodiments, the housing 401 can include a first body 402 and a second body 403. The first body 402 and the second body 403 overlap to define a storage space for the battery cells 200. The first body 402 and the second body 403 can have various shapes, such as a rectangular parallelepiped or a cylinder. The first body 402 can be a hollow structure with one side open, and the second body 403 can also be a hollow structure with one side open. The open side of the second body 403 overlaps the open side of the first body 402, forming the housing 401 with storage space. Alternatively, the first body 402 can be a hollow structure with one side open, and the second body 403 can be a plate-like structure. The second body 403 overlaps the open side of the first body 402, forming the housing 401 with storage space. As an example, the battery cell 200 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell 200 of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a polygonal battery, and a polygonal battery such as a hexagonal battery, etc. There is no special limitation in this application.

[0105] In the battery 400, there can be one or more battery cells 200. If there are multiple battery cells 200, the multiple battery cells 200 can be connected in series, parallel, or in a hybrid connection. Hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 200. Multiple battery cells 200 can be connected in series, parallel, or in a hybrid connection to form a battery module, which is then connected in series, parallel, or in a hybrid connection to form a single unit and housed within the housing 401. Alternatively, all battery cells 200 can be directly connected in series, parallel, or in a hybrid connection, and then the entire unit formed by all battery cells 200 is housed within the housing 401.

[0106] 3 and 7 , FIG3 is a schematic diagram of a battery cell 200 provided in some embodiments of the present application; FIG7 is an exploded view of a battery cell 200 provided in some embodiments of the present application. The battery cell 200 may include a housing 60 and an electrode assembly 300 .

[0107] The housing 60 is used to house the electrode assembly 300 and other components such as the electrolyte. The housing 60 can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film. As an example, the housing 60 can include a shell 10 and an end cap 20.

[0108] The housing 10 may be a hollow structure with an opening at one end, or a hollow structure with openings at two opposite ends. The housing 10 may be made of a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, and the like.

[0109] The end cap 20 is a component that closes the opening of the shell 10 to isolate the internal environment of the battery cell 200 from the external environment. The end cap 20 and the shell 10 together define a storage space for accommodating the electrode assembly 300, electrolyte and other components. The end cap 20 can be connected to the shell 10 by welding or crimping to close the opening of the shell 10. The shape of the end cap 20 can be adapted to the shape of the outer shell 60. For example, the shell 10 is a rectangular parallelepiped structure, and the end cap 20 is a rectangular plate structure adapted to the shell 10. The material of the end cap 20 can also be various, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0110] In the battery cell 200, there can be one or two end caps 20. In embodiments where the housing 10 is a hollow structure with openings at both ends, two end caps 20 can be provided. The two end caps 20 respectively close the two openings of the housing 10, and the two end caps 20 and the housing 10 together define a storage space. In embodiments where the housing 10 is a hollow structure with an opening at one end, there can be one end cap 20 provided. The end cap 20 closes the opening at one end of the housing 10, and the end cap 20 and the housing 10 together define a storage space.

[0111] The electrode assembly 300 includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell 200, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0112] 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 region disposed on at least one surface of the positive electrode current collector, wherein the positive electrode active material region has a positive electrode active material.

[0113] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material region is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0114] In some embodiments, the negative electrode may be a negative electrode sheet, which may include a negative electrode current collector and a negative electrode active material region disposed on at least one surface of the negative electrode current collector.

[0115] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material region is provided on either one or both of the two facing surfaces of the negative electrode current collector.

[0116] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0117] In some embodiments, the electrode assembly 300 further includes a separator disposed between the positive electrode and the negative electrode.

[0118] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0119] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0120] In some embodiments, the battery cell 200 further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte may be selected based on needs. The electrolyte may be liquid, gel, or solid.

[0121] In some embodiments, the electrode assembly 300 is a wound structure in which the positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0122] In some embodiments, the electrode assembly 300 is a laminated structure.

[0123] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0124] As an example, multiple positive electrode sheets may be provided, and the negative electrode sheet is folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0125] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0126] As an example, multiple separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0127] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0128] In some embodiments, the shape of the electrode assembly 300 can be flat or polygonal.

[0129] In some embodiments, the electrode assembly 300 is provided with tabs that can conduct current from the electrode assembly 300. The tabs include a positive tab and a negative tab.

[0130] The battery cell 200 may further include an electrical connector 23, which may be disposed on the housing 60. The electrical connector 23 is configured to electrically connect to the tab of the electrode assembly 300 to output electrical energy from the battery cell 200. The electrical connector 23 and the tab may be directly connected, for example, by direct welding. Alternatively, the electrical connector 23 and the tab may be indirectly connected, for example, through a current collecting member. The current collecting member may be a metal conductor, such as copper, iron, aluminum, steel, or an aluminum alloy.

[0131] As shown in Figures 3 and 7, taking the hollow structure with an opening formed at one end of the shell 10 as an example, two electrical connection parts 23 can be set on the end cover 20, and the two electrical connection parts 23 are respectively a positive electrical connection part 21 (i.e., the positive electrode column 21) and a negative electrical connection part 22 (i.e., the negative electrode column 22). The positive electrical connection part 21 is electrically connected to the positive electrode ear, and the negative electrical connection part 22 is electrically connected to the negative electrode ear.

[0132] The electrode assembly 300 includes a plurality of electrode sheets arranged in a wound manner, and an outer peripheral surface of the electrode assembly 300 includes a flat region 301 .

[0133] A plurality of electrode sheets arranged in a wound manner, i.e., positive electrode sheets and negative electrode sheets are stacked and wound around a set axis to form an electrode assembly 300. The straight area 301 refers to the portion of the electrode sheet extending along the plane when wound. The two opposite side surfaces of the electrode assembly 300 along the first direction are formed as the straight area 301.

[0134] The battery cell 200 according to an embodiment of the present application is described below with reference to FIG. 3 to FIG. 13 .

[0135] According to an embodiment of the present application, the battery cell 200 includes: an electrode assembly 300, including a positive electrode sheet and a negative electrode sheet. The positive electrode sheet and the negative electrode sheet are stacked to form a flat region 301. At least a portion of the positive electrode sheet and at least a portion of the negative electrode sheet are stacked along a first direction in the flat region 301. A housing 60 is used to accommodate the electrode assembly 300. The housing 60 includes a first wall portion 11 and two second wall portions 12 connected to the first wall portion 11. The two second wall portions 12 are located on both sides of the flat region 301 along the first direction. A pressure relief portion 40 is provided on the first wall portion 11. The pressure relief portion 40 is formed with a notched groove 41. The bottom of the notched groove 41 is formed with a first weak section 42 and a second weak section 43. The thickness of the second weak section 42 is less than that of the first weak section 43. The first weak section 42 is a straight section extending along a second direction, which is perpendicular to the first direction.

[0136] The electrode assembly 300 includes positive and negative electrode sheets. For example, the electrode assembly 300 includes at least one positive electrode sheet and at least one negative electrode sheet. The at least one positive electrode sheet and at least one negative electrode sheet are stacked to form the electrode assembly 300. The positive and negative electrode sheets are stacked to form a flat region 301. In the flat region 301, at least a portion of the positive electrode sheet and at least a portion of the negative electrode sheet are stacked along a first direction. As a result, the expansion of the electrode assembly 300 is primarily in the first direction. When the battery cell 200 is positioned in the orientation shown in FIG. 7 , the first direction refers to the Z direction in FIG. The outer circumference of the electrode assembly 300 has the flat region 301.

[0137] The electrode assembly 300 can also be of a wound type. The positive electrode sheet and the negative electrode sheet of the electrode assembly 300 are stacked with the isolation film and then wound to form a flat area 301. In the flat area 301, part of the positive electrode sheet 21 and part of the negative electrode sheet 22 are stacked along the first direction. For example, after winding, each layer of the positive electrode sheet and each layer of the negative electrode sheet can be penetrated by an axis extending along the first direction, so that most of the expansion of the electrode assembly 300 is reflected in the first direction.

[0138] The outer shell 60 defines an installation cavity 30, and the electrode assembly 300 of the battery cell 200 is installed in the installation cavity 30. The outer shell 60 includes a first wall portion 11 and two second wall portions 12. The two second wall portions 12 are respectively located on both sides of the electrode assembly 300 in the first direction. Most of the expansion of the electrode assembly 300 will act on the second wall portion 12. The first wall portion 11 is located between the two second wall portions 12.

[0139] The pressure relief portion 40 is provided on the first wall portion 11. The pressure relief portion 40 can be an explosion-proof valve, or the first wall portion 11 can have a notched structure to form the pressure relief portion 40. The pressure relief portion 40 is formed with a notched groove 41. When the pressure threshold within the mounting cavity 30 reaches a certain value, the notched groove 41 of the pressure relief portion 40 opens, and the gas and substances within the battery cell 200 are discharged from the pressure relief portion 40, achieving a pressure relief effect. The design of this pressure threshold varies according to design requirements and may depend on the material of one or more of the positive electrode sheet, negative electrode sheet, electrolyte, and separator in the battery cell 200.

[0140] When the electrode assembly 300 expands, the first wall portion 11 is affected less by the electrode assembly 300 than the second wall portion 12. Since the pressure relief portion 40 is located on the first wall portion 11, the risk of the pressure relief portion 40 being blocked or damaged by the expansion of the electrode assembly 300 can be reduced.

[0141] The bottom of the scored groove 41 is formed with a first weak section 42 and a second weak section 43. In other words, the bottom wall of the scored groove 41 is formed with the first weak section 42 and the second weak section 43. The thickness of the second weak section 43 is less than that of the first weak section 42. The first weak section 42 is a straight line extending along a second direction, which is perpendicular to the first direction. It should be noted that the first weak section 42 can extend along or substantially along the second direction, which is the longitudinal direction of the first wall portion 11.

[0142] When the electrode assembly expands, the electrode assembly pushes against the outer shell of the battery cell and pushes the outer shell outward, causing the outer shell to deform. The outer shell is the main force-bearing surface and deforms greatly. When the outer shell deforms, the deformation of the outer shell will pull the pressure relief part, causing the pressure relief part to be subjected to pulling force, which can easily cause damage to the pressure relief part and affect the normal use of the pressure relief part.

[0143] In the present application, by making the thickness of the second weak section 43 smaller than the thickness of the first weak section 42, the thickness of the bottom local position of the notched groove 41 can be thickened compared with the prior art, and when the electrode assembly 300 expands, the straight area 301 of the electrode assembly 300 presses against the second wall portion 12 to support the shell 60 outward, causing the shell 60 to deform. The second wall portion 12 of the shell 60 deforms greatly. When the second wall portion 12 deforms, the deformation of the second wall portion 12 pulls the first wall portion 11 along the first direction, causing the first wall portion 11 to deform. A weak section 42 extends along the second direction, and the thickness of the first weak section 42 is greater than the thickness of the second weak section 43. This can enhance the deformation resistance of the notched groove 41 and reduce the influence of external force or deformation on the position of the notched groove 41 of the pressure relief part 40. When the electrode assembly 300 in the battery cell 200 expands and causes the outer shell 60 to deform, the risk of tearing at the position of the notched groove 41 of the pressure relief part 40 is reduced. This can reduce the influence of the deformation of the outer shell 60 on the pressure relief part 40, thereby reducing the risk of damage to the pressure relief part 40, which is conducive to maintaining the normal use of the pressure relief part 40.

[0144] In the above technical solution, by making the thickness of the second weak section 43 smaller than the thickness of the first weak section 42 and the first weak section 42 extending along the second direction, the structural strength of the pressure relief part 40 can be improved, the deformation resistance of the notched groove 41 can be improved, and the influence of external force or deformation on the position of the notched groove 41 of the pressure relief part 40 can be reduced. When the battery cell 200 expands and causes the outer shell 60 to deform, the influence of the deformation of the outer shell 60 on the pressure relief part 40 can be reduced, thereby reducing the risk of damage to the pressure relief part 40, which is conducive to maintaining the normal use of the pressure relief part 40.

[0145] According to some embodiments of the present application, as shown in FIG. 3 , FIG. 4 , and FIG. 6 , the area of ​​the first wall portion 11 is smaller than the area of ​​the second wall portion 12 .

[0146] The housing 60 has a first wall 11 and a second wall 12 adjacent to each other. The area of ​​the second wall 12 is larger than that of the first wall 11. The second wall 12 is the larger wall of the housing 60, while the first wall 11 is the narrower wall adjacent to the second wall 12. After the electrode assembly 300 is installed in the mounting cavity 30, the second wall 12 faces the flat area 301 of the electrode assembly 300. When the pressure inside the mounting cavity 30 reaches a certain value, the notched groove 41 of the pressure relief portion 40 opens, allowing gas and substances inside the battery cell 200 to be discharged through the pressure relief portion 40, achieving a pressure relief effect.

[0147] When the electrode assembly 300 expands, the electrode assembly 300 pushes against the second wall 12 of the outer shell 60 of the battery cell 200, pushing the outer shell 60 outward, causing the outer shell 60 to deform. The second wall 12 of the outer shell 60 is the main stress-bearing surface and deforms greatly, and the force on the first wall 11 is smaller than that on the second wall 12. Therefore, by arranging the pressure relief portion 40 on the first wall 11, the pressure relief portion 40 can be arranged on a smaller stress-bearing surface of the outer shell 60. Compared with arranging the pressure relief portion 40 on the second wall 12, when the second wall 12 of the outer shell 60 deforms, the force on the pressure relief portion 40 can be reduced, thereby further improving the deformation resistance of the notched groove 41, further reducing the influence of external force or deformation on the position of the notched groove 41 of the pressure relief portion 40, and thus ensuring that the pressure relief portion 40 is positioned appropriately.

[0148] In the above technical solution, by arranging the pressure relief portion 40 on the first wall portion 11, the pressure relief portion 40 can be arranged on the smaller force-bearing surface of the shell 60. Compared with arranging the pressure relief portion 40 on the second wall portion 12, when the second wall portion 12 of the shell 60 is deformed, the force on the pressure relief portion 40 can be reduced, thereby further improving the deformation resistance of the notched groove 41, further reducing the influence of external force or deformation on the position of the notched groove 41 of the pressure relief portion 40, and thus making the pressure relief portion 40 be arranged at an appropriate position.

[0149] According to some embodiments of the present application, the pressure relief portion 40 is configured to rupture at the second weak section 43 when the internal pressure or temperature of the housing 60 reaches a threshold value.

[0150] Among them, by setting the thickness of the second weak section 43 to be smaller than the thickness of the first weak section 42, the thickness of the second weak section 43 is made relatively thinner. When the internal pressure or temperature of the shell 60 reaches a threshold, under the action of the internal pressure of the shell 60, the bottom wall of the notched groove 41 preferentially cracks in the second weak section 43, tearing the bottom wall of the notched groove 41. When thermal runaway occurs in the battery cell 200, it can crack from the second weak section 43 and the first weak section 4, and can also improve the reliability of the notched groove 41 and reduce the risk of rupture of the notched groove 41 during normal use of the battery cell 200.

[0151] In the above technical solution, by configuring the pressure relief portion 40 to crack at the second weak section 43, when the internal pressure or temperature of the outer shell 60 reaches a threshold value, under the action of the internal pressure of the outer shell 60, the bottom wall of the notched groove 41 preferentially cracks at the second weak section 43, tearing the bottom wall of the notched groove 41. When thermal runaway occurs in the battery cell 200, it can crack from the second weak section 43 and the first weak section 4, and during the normal use of the battery cell 200, it can improve the reliability of the notched groove 41 and reduce the risk of rupture of the notched groove 41.

[0152] According to some embodiments of the present application, as shown in FIG. 8 , FIG. 12 and FIG. 13 , the scoring groove 41 may include a first straight groove segment 45 extending along the second direction, and a first weak section 42 is formed at the bottom of the first straight groove segment 45 .

[0153] The scored groove 41 includes a first linear groove segment 45, which may be a linear groove segment or may be similar to a linear groove segment. The first linear groove segment 45 extends along a second direction, which may be parallel to the lengthwise direction of the pressure relief portion 40 (the lengthwise direction of the pressure relief portion 40 is the X direction in FIG8 ). A first weakened section 42 is formed on the bottom wall of the first linear groove segment 45, so that the first weakened section 42 is disposed on the bottom wall of the first linear groove segment 45.

[0154] It should be noted that when the electrode assembly 300 expands, the electrode assembly 300 presses against the second wall portion 12 to support the outer shell 60 outward, causing the outer shell 60 to deform. The second wall portion 12 deforms greatly. When the second wall portion 12 deforms, the deformation of the second wall portion 12 will pull the first wall portion 11 along the first direction, causing the first wall portion 11 to deform. When the pressure relief portion 40 is installed on the first wall portion 11, the first straight groove segment 45 is subjected to a large force.

[0155] In the above technical solution, a first weak section 42 is formed at the bottom of the first straight groove section 45, which can enhance the deformation resistance of the first straight groove section 45, reduce the influence of external force or deformation on the position of the first straight groove section 45 of the pressure relief part 40, and thereby make the first weak section 42 be set at an appropriate position.

[0156] According to some embodiments of the present application, as shown in FIG. 3 to FIG. 7 , the first straight slot segment 45 is disposed opposite to the second wall portion 12 .

[0157] Among them, when the electrode assembly 300 expands, the electrode assembly 300 presses against the second wall portion 12 of the outer shell 60 to support the outer shell 60 outward, causing the outer shell 60 to deform, and the second wall portion 12 deforms greatly. When the second wall portion 12 deforms, the deformation of the second wall portion 12 will pull the first wall portion 11, causing the first wall portion 11 to deform. The middle position of the second wall portion 12 is the most deformed, so that the middle position of the first wall portion 11 is subjected to the greatest pulling force. When the pressure relief portion 40 is installed on the first wall portion 11, the first straight groove segment 45 is arranged opposite to the second wall portion 12. The first straight groove segment 45 can be parallel to the second wall portion 12, or the first straight groove segment 45 can be roughly parallel to the second wall portion 12. By arranging the first straight groove segment 45 and the second wall portion 12 opposite to each other, the part of the notched groove 41 where the first weak section 42 is formed can be arranged corresponding to the second wall portion 12. When the first wall portion 11 is deformed, the force can be applied to the part of the notched groove 41 where the first weak section 42 is formed, which is beneficial to improving the deformation resistance of the notched groove 41.

[0158] According to some embodiments of the present application, as shown in FIG. 9 , the length of the first weak section 42 is smaller than the length of the first straight slot section 45 .

[0159] Among them, the length dimension of the first weak section 42 is L1, and the length dimension of the first straight groove section 45 is L2, satisfying the relationship: L1<L2. By making the length dimension of the first weak section 42 smaller than the length dimension of the first straight groove section 45, the thickness of the local position of the bottom wall of the first straight groove section 45 can be thickened. On the basis of improving the deformation resistance of the notched groove 41, when the pressure in the installation cavity 30 reaches a certain pressure, the notched groove 41 can be smoothly torn open to achieve a pressure relief effect, thereby reducing the risk of the notched groove 41 not being able to open when the pressure in the installation cavity 30 reaches a certain pressure, thereby improving the safety of the battery cell 200.

[0160] In the above technical solution, by making the length dimension of the first weak section 42 smaller than the length dimension of the first straight groove section 45, the thickness of the local position of the bottom wall of the first straight groove section 45 can be thickened. On the basis of improving the deformation resistance of the notched groove 41, when the pressure in the installation cavity 30 reaches a certain pressure, the notched groove 41 can be smoothly torn open to achieve a pressure relief effect, thereby reducing the risk that the notched groove 41 cannot be opened when the pressure in the installation cavity 30 reaches a certain pressure, and improving the safety of the battery cell 200.

[0161] According to some embodiments of the present application, as shown in FIG. 9 , the ratio of the length of the first weak section 42 to the length of the first straight slot section 45 is greater than or equal to 0.5 and less than or equal to 0.9.

[0162] Among them, the length dimension of the first weak section 42 is L1, and the length dimension of the first straight groove section 45 is L2, satisfying the relationship: 0.5≤L1 / L2≤0.9, for example: L1 / L2 is 0.5, 0.6, 0.8, 0.9 and other values. By making the ratio of the length dimension of the first weak section 42 to the length dimension of the first straight groove section 45 greater than or equal to 0.5 and less than or equal to 0.9, the length dimension ratio of the first weak section 42 formed in the first straight groove section 45 can be appropriate. On the basis of better improving the deformation resistance of the notched groove 41, when the pressure in the installation cavity 30 reaches a certain pressure, the notched groove 41 can be quickly torn open smoothly to achieve a rapid pressure relief effect.

[0163] In the above technical solution, by making the ratio of the length dimension of the first weak section 42 to the length dimension of the first straight groove section 45 greater than or equal to 0.5 and less than or equal to 0.9, the length dimension ratio of the first weak section 42 formed in the first straight groove section 45 can be appropriate. On the basis of better improving the deformation resistance of the notched groove 41, when the pressure in the installation cavity 30 reaches a certain pressure, the notched groove 41 can be quickly torn open smoothly to achieve a rapid pressure relief effect.

[0164] According to some embodiments of the present application, as shown in FIG. 9 , FIG. 12 and FIG. 13 , along the second direction, the first weak section 42 is located in the middle of the first straight slot section 45 .

[0165] The second direction refers to the X-direction in Figures 9, 12, and 13. In other words, along the length of the first linear slot segment 45, the first weak section 42 is formed in the middle of the bottom wall of the first linear slot segment 45. After the pressure relief portion 40 is installed on the first wall portion 11, the first linear slot segment 45 corresponds to the second wall portion 12. The middle of the first linear slot segment 45 is subject to high stress and is prone to tearing. By arranging the first weak section 42 in the middle of the first linear slot segment 45, the first weak section 42 can be placed in a relatively high-stress position on the scored groove 41, which is more conducive to improving the deformation resistance of the scored groove 41, thereby ensuring the optimal placement of the first weak section 42.

[0166] In the above technical solution, by setting the first weak section 42 in the middle position of the first straight groove section 45, the structural reinforcement section 50 can be arranged at a position where the force on the notched groove 41 is relatively large, which is more conducive to improving the deformation resistance of the notched groove 41, thereby making the arrangement position of the first weak section 42 reasonable.

[0167] According to some embodiments of the present application, as shown in FIG9 , FIG12 and FIG13 , the first weak section 42 is symmetrical about a middle section 49 of the first straight slot section 45 , and the middle section 49 is perpendicular to the second direction.

[0168] In particular, along the second direction, the middle section 49 is located in the middle of the first linear slot segment 45, and the middle section 49 is perpendicular to the second direction and parallel to the first direction. Since the first weak section 42 is symmetrical about the middle section 49 of the first linear slot segment 45, the first weak section 42 can be positioned at the center of the first linear slot segment 45. After the pressure relief portion 40 is installed on the first wall portion 11, the first linear slot segment 45 corresponds to the second wall portion 12. This allows the first weak section 42 to be positioned at a relatively high-stress location on the scored groove 41, ensuring uniform stress distribution on the first linear slot segment 45, further enhancing the structural strength of the scored groove 41 and improving its anti-deformation capability, thereby ensuring a reasonable placement of the first weak section 42.

[0169] In the above technical solution, the first weak section 42 is symmetrical about the middle section 49 of the first straight groove section 45, so that the first weak section 42 can be set at the center position of the first straight groove section 45. After the pressure relief portion 40 is installed on the first wall portion 11, the first straight groove section 45 corresponds to the second wall portion 12, so that the first weak section 42 can be arranged at a position where the force on the notched groove 41 is relatively large, so that the first straight groove section 45 can be evenly stressed, further improving the structural strength of the notched groove 41, and more conducive to improving the deformation resistance of the notched groove 41, so that the first weak section 42 is arranged at a reasonable position.

[0170] According to some embodiments of the present application, as shown in FIG. 11 , along the depth direction of the scoring groove 41 , the difference between the thickness of the second weak section 43 and the thickness of the first weak section 42 is greater than 0.05 and less than or equal to 0.45 mm.

[0171] Among them, along the depth direction of the scored groove 41, the difference between the thickness dimension of the first weak section 42 and the thickness dimension of the second weak section 43 is T, satisfying the relationship: 0.05mm<T≤0.45mm, for example: the difference between the thickness dimension of the first weak section 42 and the thickness dimension of the second weak section 43 is 0.05mm, 0.2mm, 0.3mm, 0.45mm. By making the difference between the thickness dimension of the second weak section 43 and the thickness dimension of the first weak section 42 greater than 0.05 and less than or equal to 0.45mm, the thickness dimension of the first weak section 42 can be made appropriate, that is, the deformation resistance of the scored groove 41 can be improved, and when the pressure in the installation cavity 30 reaches a certain pressure, the scored groove 41 can also be smoothly torn open.

[0172] In the above technical solution, by making the difference between the thickness dimension of the second weak section 43 and the thickness dimension of the first weak section 42 greater than 0.05 and less than or equal to 0.45 mm, the thickness dimension of the first weak section 4 can be made appropriate, that is, the deformation resistance of the notched groove 41 can be improved, and when the pressure in the installation cavity 30 reaches a certain pressure, the notched groove 41 can also be smoothly torn open.

[0173] According to some embodiments of the present application, as shown in FIG. 9 , the scoring groove 41 includes two first straight groove segments 45 extending along the second direction, and a first weak section 42 is formed at the bottom of each first straight groove segment 45 .

[0174] In which, the scoring groove 41 can include two first straight groove segments 45, the two first straight groove segments 45 extend along the second direction, and the two first straight groove segments 45 are arranged along the first direction, for example: the two first straight groove segments 45 are spaced apart along the first direction, and the bottom wall of each first straight groove segment 45 is formed with a first weak section 42.

[0175] In the above technical solution, two first straight groove sections 45 extend along the second direction, and a first weak section 42 is formed on the bottom wall of each first straight groove section 45. When the electrode assembly 300 expands, the electrode assembly 300 pushes the second wall portion 12 outward, causing the outer shell 60 to deform. When the second wall portion 12 deforms, the deformation of the second wall portion 12 will pull the first wall portion 11, causing the first wall portion 11 to deform. The middle position of the second wall portion 12 is the most deformed, so that the middle position of the first wall portion 11 is subjected to the greatest pulling force. When the pressure relief portion 40 is installed on the first wall portion 11, the two first straight groove segments 45 extend along the second direction, and the two first straight groove segments 45 are arranged along the first direction. A first weak section 42 is formed at the bottom of each first straight groove segment 45, so that the portion of the notched groove 41 formed with the first weak section 42 can be arranged corresponding to the second wall portion 12. When the first wall portion 11 is deformed, the force can be applied to the portion of the notched groove 41 formed with the first weak section 42, which is beneficial to improving the deformation resistance of the notched groove 41.

[0176] According to some embodiments of the present application, as shown in Figure 9, the two first weak sections 42 include a first section 421 and a second section 422, the thickness of the first section 421 is less than the thickness of the second section 422, and the pressure relief portion 40 is configured so that when the internal pressure or temperature of the housing 60 reaches a threshold value, the first section 421 is completely ruptured, and at least a portion of the second section 422 is not ruptured.

[0177] Among them, the notched groove 41 includes two first straight groove sections 45, and a first weak section 42 is formed at the bottom of each first straight groove section 45. The two first straight groove sections 45 form two first weak sections 42 in total. Each first weak section 42 can include a first section 421 and a second section 422. The thickness of the first section 421 is less than the thickness of the second section 422. The pressure relief portion 40 is configured so that when the internal pressure or temperature of the outer shell 60 reaches a threshold value, the first section 421 is completely cracked, and at least a part of the second section 422 is not cracked. This arrangement can achieve a pressure relief effect on the battery cell 200, and can also reduce the risk of the pressure relief portion 40 flying out of the battery cell 200, reducing the risk of the pressure relief portion 40 flying out of the battery cell 200 to personal safety.

[0178] In the above technical solution, the thickness of the first section 421 is smaller than the thickness of the second section 422, and the pressure relief portion 40 is configured so that when the internal pressure or temperature of the outer shell 60 reaches a threshold value, the first section 421 completely breaks open, and at least a portion of the second section 422 does not break open. This can enable the battery cell 200 to achieve a pressure relief effect, and can also reduce the risk of the pressure relief portion 40 flying out of the battery cell 200, thereby reducing the risk to personal safety caused by the pressure relief portion 40 flying out of the battery cell 200.

[0179] According to some embodiments of the present application, as shown in FIG. 9 , the two first weak sections 42 are equal in length.

[0180] Among them, the notched groove 41 includes two first straight groove sections 45, and a first weak section 42 is formed at the bottom of each first straight groove section 45. The two first straight groove sections 45 form two first weak sections 42 in total, and the lengths of the two first weak sections 42 are equal. When the electrode assembly 300 expands, such a setting can make the notched groove 41 evenly stressed, further improve the deformation resistance of the notched groove 41, further reduce the risk of tearing at the notched groove 41 position of the pressure relief part 40, and further reduce the impact of the deformation of the shell 60 on the pressure relief part 40.

[0181] In the above technical solution, by making the lengths of the two first weak sections 42 equal, when the electrode assembly 300 expands, the force on the notched groove 41 can be evenly distributed, thereby further improving the deformation resistance of the notched groove 41 and further reducing the risk of tearing at the notched groove 41 of the pressure relief part 40, thereby further reducing the influence of the deformation of the outer shell 60 on the pressure relief part 40.

[0182] According to some embodiments of the present application, as shown in Figure 9, the scoring groove 41 includes two first arcuate groove segments 46, and the two ends of each first straight groove segment 45 are respectively connected to the two first arcuate groove segments 46 to make the scoring groove 41 constructed into a ring shape, and a second weak section 43 is formed at the bottom of the first arcuate groove segment 46.

[0183] As shown in Figure 9, the scoring groove 41 includes two first straight groove segments 45 and two first arcuate groove segments 46. The first arcuate groove segment 46 can be arc-shaped. The two first arcuate groove segments 46 are arranged opposite to each other and spaced apart along the second direction. The two first straight groove segments 45 are arranged opposite to each other and spaced apart along the first direction. The two first straight groove segments 45 are parallel. The two ends of each first straight groove segment 45 are respectively connected to the two first arcuate groove segments 46. The two first straight groove segments 45 and the two first arcuate groove segments 46 constitute a closed annular structure, so that the scoring groove 41 is constructed in an annular shape, and the bottom wall of the first arcuate groove segment 46 is formed with a second weak section 43. When the internal pressure or temperature of the shell 60 reaches a threshold value, the second weak section 43 of the bottom wall of the first arc-shaped groove section 46 will crack, which is conducive to the tearing of the notched groove 41 to release pressure, thereby enabling the battery cell 200 to achieve a pressure relief effect, and also reducing the risk of the pressure relief portion 40 flying out of the battery cell 200, thereby reducing the risk of the pressure relief portion 40 flying out of the battery cell 200 to personal safety.

[0184] In the above technical solution, the notched groove 41 is constructed into a ring shape, and a second weak section 43 is formed on the bottom wall of the first arcuate groove section 46. When the internal pressure or temperature of the outer shell 60 reaches a threshold value, the second weak section 43 of the bottom wall of the first arcuate groove section 46 is cracked, which is conducive to the tearing and pressure relief of the notched groove 41, and can achieve the pressure relief effect of the battery cell 200, and can also reduce the risk of the pressure relief portion 40 flying out of the battery cell 200, reducing the risk of the pressure relief portion 40 flying out of the battery cell 200 to personal safety.

[0185] According to some embodiments of the present application, as shown in FIG. 12 , the scoring groove 41 includes a first straight groove segment 45 extending along the second direction, and a first weak section 42 is formed at the bottom of the first straight groove segment 45 .

[0186] In this embodiment, the scored groove 41 includes a first linear groove segment 45, the bottom wall of which is formed with a first weak section 42. Due to the first weak section 42 formed on the bottom wall of the first linear groove segment 45, when the electrode assembly 300 expands, the electrode assembly 300 pushes against the second wall portion 12 and pushes it outward, causing the housing 60 to deform. When the second wall portion 12 deforms, the deformation pulls on the first wall portion 11, causing the first wall portion 11 to deform the most. The center of the second wall portion 12 deforms the most, causing the center of the first wall portion 11 to be subjected to the greatest pulling force. When the pressure relief portion 40 is mounted on the first wall portion 11, the first linear groove segment 45 extends in the second direction, enabling the portion of the scored groove 41 formed with the first weak section 42 to correspond to the second wall portion 12. When the first wall portion 11 deforms, the force acts on the portion of the scored groove 41 formed with the first weak section 42, thereby improving the deformation resistance of the scored groove 41.

[0187] In the above technical solution, the notched groove 41 includes a first straight groove segment 45, and a first weak segment 42 is formed at the bottom of the first straight groove segment 45, so that the portion of the notched groove 41 where the first weak segment 42 is formed can be arranged corresponding to the second wall portion 12. When the first wall portion 11 is deformed, the force can be applied to the portion of the notched groove 41 where the first weak segment 42 is formed, which is beneficial to improving the deformation resistance of the notched groove 41.

[0188] According to some embodiments of the present application, as shown in FIG12 and FIG13 , the scoring groove 41 includes a first straight groove segment 45 and four second straight groove segments 47 . The two ends of the first straight groove segment 45 are respectively connected to two second straight groove segments 47 arranged at a preset angle. The bottom of the second straight groove segment 47 is formed with a second weak section 43 . Or,

[0189] The notched groove 41 includes a first straight groove segment 45 and two third straight groove segments 48. The two ends of the first straight groove segment 45 are respectively connected to the third straight groove segments 48, and the third straight groove segments 48 are perpendicular to the first straight groove segment 45. A second weak section 43 is formed at the bottom of the third straight groove segment 48.

[0190] As shown in FIG12 , the notched groove 41 includes a first straight groove segment 45 and four second straight groove segments 47 . The two ends of the first straight groove segment 45 are respectively connected to two second straight groove segments 47 set at a preset angle. The bottom wall of the third straight groove segment 48 is formed with a second weak section 43 , which can form a double Y-shaped notched groove 41 at both ends of the notched groove 41 . When the pressure in the mounting cavity 30 reaches a certain pressure or the temperature reaches a threshold, the internal pressure of the mounting cavity 30 can be released from the double Y-shaped notched groove 41 , thereby quickly releasing the pressure of the battery cell 200 .

[0191] In the above technical solution, the notched groove 41 includes a first straight groove segment 45 and four second straight groove segments 47, and the bottom wall of the third straight groove segment 48 is formed with a second weak section 43, so that the two ends of the notched groove 41 can form a double Y-shaped notched groove 41. When the pressure in the installation cavity 30 reaches a certain pressure or the temperature reaches a threshold, the internal pressure of the installation cavity 30 can be released from the double Y-shaped notched groove 41, thereby quickly releasing the pressure of the battery cell 200.

[0192] According to some embodiments of the present application, as shown in Figure 13, the scoring groove 41 includes a first straight groove segment 45 and two third straight groove segments 48, and the two ends of the first straight groove segment 45 are respectively connected to the third straight groove segments 48, and the third straight groove segments 48 are perpendicular to the first straight groove segment 45, and a second weak section 43 is formed at the bottom of the third straight groove segment 48.

[0193] As shown in FIG13 , the scored groove 41 includes a first linear groove segment 45 and two third linear groove segments 48. The first linear groove segment 45 extends along the second direction, and the two third linear groove segments 48 are spaced apart and opposite to each other along the second direction. The first linear groove segment 45 is connected to a third linear groove segment 48 at each end, and the third linear groove segments 48 are perpendicular or substantially perpendicular to the first linear groove segment 45. By including a first linear groove segment 45 and two third linear groove segments 48, the scored groove 41 can be configured into an "I" shape. The bottom wall of the third linear groove segment 48 is formed with a second weak section 43. When the pressure within the mounting cavity 30 reaches a certain pressure or the temperature reaches a threshold, the first linear groove segment 45 and the two third linear groove segments 48 can tear open, allowing the pressure within the mounting cavity 30 to escape through the first linear groove segment 45 and the third linear groove segment 48, thereby increasing the pressure relief rate of the battery cell 200.

[0194] In the above technical solution, the notched groove 41 includes a first straight groove segment 45 and two third straight groove segments 48, so that the notched groove 41 can be constructed into an "I"-shaped structure, and the bottom wall of the third straight groove segment 48 is formed with a second weak section 43. When the pressure in the installation cavity 30 reaches a certain pressure or the temperature reaches a threshold, the first straight groove segment 45 and the two third straight groove segments 48 can be torn open, and the internal pressure of the installation cavity 30 can be released from the first straight groove segment 45 and the third straight groove segment 48, which can increase the pressure relief speed of the battery cell 200.

[0195] According to some embodiments of the present application, as shown in FIG. 3 and FIG. 6 , along the second direction, the center of the pressure relief portion 40 and the center of the first wall portion 11 are offset.

[0196] Among them, along the second direction, that is, along the length direction of the first wall portion 11, in the embodiment shown in Figure 3, the second direction refers to the X1 direction in Figure 3, and in the embodiment shown in Figure 6, the second direction refers to the X2 direction in Figure 6. Along the second direction, the center of the pressure relief portion 40 and the center of the first wall portion 11 are staggered.

[0197] When the electrode assembly 300 expands, the electrode assembly 300 pushes against the second wall portion 12 to support the outer shell 60, causing the outer shell 60 to deform. The second wall portion 12 is the main force-bearing surface and deforms greatly. When the second wall portion 12 deforms, the deformation of the second wall portion 12 will pull the first wall portion 11, causing the first wall portion 11 to deform. Since the middle position of the second wall portion 12 deforms the most, the middle position of the first wall portion 11 is subjected to the greatest pulling force along the second direction, thereby causing the pressure relief portion 40 to be subjected to pulling force, which can easily cause damage to the pressure relief portion 40 and affect the normal use of the pressure relief portion 40.

[0198] In the present application, along the length direction of the first wall portion 11, that is, along the second direction, by staggering the center of the pressure relief portion 40 and the center of the first wall portion 11, the pressure relief portion 40 can be eccentrically arranged toward one side of the first wall portion 11, thereby increasing the spacing distance between the center of the pressure relief portion 40 and the center of the first wall portion 11 along the second direction. When the electrode assembly 300 expands and deforms the second wall portion 12, the pulling force on the pressure relief portion 40 can be reduced, and the risk of tearing the notched groove 41 of the pressure relief portion 40 is reduced, thereby reducing the impact of the deformation of the shell 60 on the pressure relief portion 40, and further reducing the risk of damage to the pressure relief portion 40, which is conducive to maintaining the normal use of the explosion-proof portion.

[0199] In the above technical solution, by staggering the center of the pressure relief portion 40 and the center of the first wall portion 11 along the second direction, the pressure relief portion 40 is disposed offset from the center of the first wall portion 11. When the battery cell 200 expands and causes the outer casing 60 to deform, the pulling force applied to the pressure relief portion 40 can be reduced, thereby reducing the influence of the deformation of the outer casing 60 on the notch groove 41 of the pressure relief portion 40, and further reducing the risk of damage to the pressure relief portion 40, which is beneficial to maintaining the normal use of the explosion-proof portion.

[0200] According to some embodiments of the present application, as shown in FIG. 15, along the second direction, the length dimension of the pressure relief portion 40 is D, the spacing distance between the center of the pressure relief portion 40 and the center of the first wall portion 11 is L, and the length of the first wall portion 11 is E, satisfying the relational expression: D / 2 < L < (E / 2 - D / 2) - 2.

[0201] Wherein, as shown in FIG. 15, along the second direction, the length dimension of the pressure relief portion 40 is D mm, the spacing distance between the center of the pressure relief portion 40 and the center of the first wall portion 11 is L mm, and the length dimension of the first wall portion 11 is E mm, satisfying the relational expression: D / 2 < L < (E / 2 - D / 2) - 2, that is to say, the spacing distance between the center of the pressure relief portion 40 and the center of the first wall portion 11 is greater than half of the length dimension of the pressure relief portion 40, and the spacing distance between the center of the pressure relief portion 40 and the center of the first wall portion 11 is less than the difference between half of the length dimension of the first wall portion 11 and half of the length dimension of the pressure relief portion 40 minus 2.

[0202] In the above technical solution, by D / 2 < L < (E / 2 - D / 2) - 2, the spacing distance between the center of the pressure relief portion 40 and the center of the first wall portion 11 along the second direction can be made appropriate. When the electrode assembly expands and causes the second wall portion 12 of the outer casing 60 to deform, on the basis of reducing the pulling force applied to the pressure relief portion 40, the pressure relief portion 40 can be smoothly opened to achieve the pressure relief effect, reduce the explosion risk of the battery cell 200, and improve the use safety of the battery cell 200.

[0203] According to some embodiments of the present application, the pressure relief portion 40 and the first wall portion 11 are integrally formed; or,

[0204] The pressure relief portion 40 and the first wall portion 11 are separately provided, the first wall portion 11 is provided with a through hole 15, and the pressure relief portion 40 is installed in the through hole 15.

[0205] When the pressure relief portion 40 is integrally formed with the first wall portion 11, a notch 41 can be provided on the first wall portion 11, forming a weak area of ​​the first wall portion 11 in the area where the notch 41 is provided. This simplifies the molding of the pressure relief portion 40 and reduces production costs. In the above technical solution, by integrally forming the pressure relief portion 40 and the first wall portion 11, the molding of the pressure relief portion 40 is simplified, the number of components comprising the battery cell 200 can be reduced, the structure of the battery cell 200 can be simplified, and the manufacturing cost of the battery cell 200 can be reduced.

[0206] Alternatively, as shown in Figures 3 and 7 , the pressure relief portion 40 is provided separately from the first wall portion 11. The pressure relief portion 40 and the housing 60 are two separate components that are separately molded and then assembled together. Specifically, the pressure relief portion 40 can be a component such as an explosion-proof disk, an explosion-proof valve, or a safety valve. The pressure relief portion 40 can be attached to the first wall portion 11 by bonding, welding, or other means. The first wall portion 11 is provided with a through hole 15, and the pressure relief portion 40 is attached to the through hole 15. When the internal pressure or temperature of the battery cell 200 reaches a threshold, the pressure relief portion 40 opens at least a portion of the through hole 15, and the exhaust medium within the battery cell 200 is discharged through the through hole 15 to relieve the pressure within the battery cell 200. In the above technical solution, by constructing the pressure relief portion 40 and the first wall portion 11 as separate components, it is convenient to install the pressure relief portion 40 on the housing 60, which reduces the manufacturing difficulty and improves the efficiency, thereby improving the production efficiency of the battery cell 200.

[0207] For example, the pressure relief portion 40 is a bursting disc, which is a sheet having at least a portion of its strength less than that of the first wall portion 11. The bursting disc covers the through-hole 15 and is welded to the first wall portion 11. When the internal pressure or temperature of the battery cell 200 reaches a threshold, the bursting disc is at least partially destroyed, thereby opening at least a portion of the through-hole 15 to release the pressure within the battery cell 200.

[0208] According to some embodiments of the present application, as shown in Figures 3, 6 and 7, the housing 60 includes a shell 10 and an end cover 20, at least one side of the shell 10 has an opening, the end cover 20 is connected to the shell 10 and is used to close the opening, and the first wall portion 11 is formed on the shell 10.

[0209] The shell 10 may be a hollow structure with an opening at one end, or a hollow structure with openings at two opposite ends. The shell 10 may be in various shapes, such as a prismatic shape. The end cap 20 is a component that closes the opening of the shell 10 to isolate the internal environment of the battery cell 200 from the external environment. The end cap 20 and the shell 10 together define a mounting cavity 30 for accommodating the electrode assembly 300, the electrolyte, and other components. The shape of the end cap 20 may be compatible with the shape of the shell 10. For example, if the shell 10 is a rectangular parallelepiped structure, the end cap 20 may be a rectangular plate-shaped structure that is compatible with the shell 10. For another example, if the shell 10 is a cylindrical structure, the end cap 20 may be a circular plate-shaped structure that is compatible with the shell 10. The material of the end cap 20 may also be various, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the end cap 20 and the shell 10 may be the same or different.

[0210] In an embodiment where the housing 10 is open at one end, one end cap 20 may be provided. In an embodiment where the housing 10 is open at two opposite ends, two end caps 20 may be provided. The two end caps 20 respectively close the two openings of the housing 10, and the two end caps 20 and the housing 10 together define a mounting cavity 30.

[0211] The shell 10 has a first wall portion 11 and a second wall portion 12. The first wall portion 11 is formed on the shell 10. The pressure relief portion 40 can be integrally formed with the shell 10 or can be separately provided from the shell 10. By providing the pressure relief portion 40 on the shell 10, the structure of the end cover 20 can be simplified, and at the same time, it is convenient to shorten the distance between the pressure relief portion 40 and the main body of the electrode assembly 300, thereby shortening the path of the discharge medium flowing to the pressure relief portion 40 during pressure relief, shortening the time for the discharge medium to reach the pressure relief portion 40, and improving the timeliness of the pressure relief of the battery cell 200, thereby effectively improving the reliability of the battery cell 200.

[0212] In the above technical solution, the first wall portion 11 is formed on the shell 10, which can simplify the structure of the end cover 20 and facilitate shortening the distance between the pressure relief portion 40 and the main body of the electrode assembly 300. This can shorten the path of the discharge medium flowing to the pressure relief portion 40 during pressure relief, shorten the time for the discharge medium to reach the pressure relief portion 40, and improve the timeliness of the pressure relief of the battery cell 200, thereby effectively improving the reliability of the battery cell 200.

[0213] According to some embodiments of the present application, as shown in FIG. 14 , the housing 10 has openings on two opposite sides, and the two end covers 20 are used to close the openings on the corresponding sides.

[0214] As shown in FIG. 14 , in an embodiment where the shell 10 has openings formed at opposite ends, two end covers 20 may be provided. The two end covers 20 respectively close the two openings of the shell 10 , and the two end covers 20 and the shell 10 together define an installation cavity 30 .

[0215] In the above technical solution, the shell 10 has openings on both sides thereof, and the two end covers 20 are used to close the openings on the corresponding sides, which can jointly define the installation cavity 30. In addition, it is convenient for the manufacturing and forming of the shell 10, and it is convenient for the electrode assembly 300 to lead out the pole ears from both ends, thereby facilitating the separation and arrangement of the two electrical connection parts 23, thereby reducing the risk of short circuit of the battery cell 200.

[0216] According to some embodiments of the present application, as shown in FIG14 , the end cap 20 is provided with an electrical connection portion 23 , and the electrical connection portion 23 is electrically connected to the positive electrode sheet, or the electrical connection portion 23 is electrically connected to the negative electrode sheet.

[0217] Among them, the electrical connection part 23 is arranged on the end cover 20, the electrical connection part 23 can be a part of the end cover 20, and the electrical connection part 23 can also be a pole installed on the end cover 20; usually there are two electrical connection parts 23, one electrical connection part 30 is the positive pole column 21 and is electrically connected to the pole tab of the positive pole sheet, and the other electrical connection part 30 is the negative pole column 22 and is electrically connected to the pole tab of the negative pole sheet to input or output the electrical energy of the battery cell 200, the electrical connection part 23 and the pole tab can be directly connected, for example, the electrical connection part 23 and the pole tab are directly welded, and the electrical connection part 23 and the pole tab can also be indirectly connected, for example, the electrical connection part 23 and the pole tab are indirectly connected through a current collecting component, and the current collecting component can be a metal conductor, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0218] The electrical connection portion 23 and the pressure relief portion 40 are located on different sides of the housing 10, that is, the electrical connection portion 23 is located on one wall portion of the housing 60, and the pressure relief portion 40 is located on the other wall portion of the housing 60. Because the electrical connection portion 23 is connected to the tab of the electrode assembly 300, there is a certain gap between the wall portion where the electrical connection portion 23 is located and the main body portion of the electrode assembly 300. By arranging the electrical connection portion 23 and the pressure relief portion 40 on different walls of the housing 60, the distance between the pressure relief portion 40 and the main body portion can be shortened. Therefore, when the battery cell 200 thermally runs away, most of the exhaust medium in the housing 60 can flow directly from the edge of the main body portion to the pressure relief portion 40, thereby shortening the path for the exhaust medium to flow to the pressure relief portion 40, allowing the exhaust medium to flow quickly to the pressure relief portion 40, shortening the time it takes for the exhaust medium to reach the pressure relief portion 40, and improving the timeliness of the pressure relief of the battery cell 200, thereby effectively improving the reliability of the battery cell 200.

[0219] In the above technical solution, the electrical energy of the battery cell 200 can be input or output by electrically connecting the electrical connection portion 23 to the positive electrode plate, or electrically connecting the electrical connection portion 23 to the negative electrode plate.

[0220] According to some embodiments of the present application, as shown in FIG. 3 , FIG. 4 and FIG. 7 , the first wall portion 11 is used to support the electrode assembly 300 and is located below the electrode assembly 300 .

[0221] The housing 10 has a housing bottom wall 13 opposite to and spaced apart from the end cover 20 . The housing bottom wall 13 is configured as a first wall portion 11 . The first wall portion 11 can support the electrode assembly 300 .

[0222] In the above technical solution, the electrode assembly 300 is supported by the first wall portion 11 , so that the electrode assembly 300 can be stably installed in the installation cavity 30 of the housing 60 .

[0223] According to some embodiments of the present application, the material of the housing 60 includes at least one of aluminum, nickel-plated carbon steel, stainless steel, magnesium alloy, nickel alloy, copper alloy and zirconium alloy.

[0224] The shell 10 of the housing 60 can be made of nickel-plated carbon steel, such as SPCC. The shell 10 can also be made of stainless steel, such as SUS304, SUS316, etc. The shell 10 can also be made of a magnesium alloy, such as AZ31B. The shell 10 can also be made of a nickel alloy, such as Inconcel625. The shell 10 can also be made of a copper alloy, such as brass. The shell 10 can also be made of a zirconium alloy, such as Zr702. Of course, the shell 10 can also be made of a composite material. By using the above materials, the tensile strength of the wall of the shell 10 can be increased, thereby reducing the deformation of the shell 10 when the electrode assembly 300 expands, reducing the probability of the shell 10 or the pressure relief portion 40 being pulled and broken, reducing the risk of leakage, and improving the reliability of the battery cell 200. The end cap 20 and the shell 10 can be made of the same material or different materials. By making the shell 60 of at least one of aluminum, nickel-plated carbon steel, stainless steel, magnesium alloy, nickel alloy, copper alloy and zirconium alloy, the structural strength of the shell 60 can be improved, which is also beneficial to reducing the manufacturing cost of the shell 60.

[0225] According to some embodiments of the present application, the positive electrode plate includes a positive electrode current collector and a positive electrode active material region arranged on the surface of the positive electrode current collector, and the constituent material of the positive electrode current collector includes aluminum element with a mass percentage greater than or equal to 50%.

[0226] That is, the constituent material of the positive electrode current collector may include aluminum, and the mass percentage of aluminum in the positive electrode current collector is greater than or equal to 50%. By adopting the above-mentioned positive electrode current collector, compared with the composite current collector in the prior art, the manufacturing difficulty of the positive electrode sheet can be reduced, and the manufacturing cost can be reduced at the same time.

[0227] According to some embodiments of the present application, the tensile strength of the first wall portion 11 is not less than 400 MPa.

[0228] Among them, the tensile strength of the first wall portion 11 can be 400 MPa, or it can be greater than 400 MPa, for example, 500 MPa, 600 MPa, 700 MPa, etc., and the tensile strength of the second wall portion 12 can be 400 MPa, or it can be greater than 400 MPa, for example, any point value among 500 MPa, 600 MPa, 700 MPa or a range value between any two of them; by limiting the tensile strength of the wall portion of the shell 10, the tensile strength of the shell 10 is improved, and the deformation of the shell 10 when the electrode assembly 300 expands is reduced, thereby reducing the pulling on the surface where the pressure relief portion 40 is located, reducing the probability of the shell 10 or the pressure relief portion 40 being pulled and broken, reducing the risk of leakage, and improving the reliability of the battery cell 200.

[0229] As shown in Figures 3 and 7, the housing 60 includes a shell 10 and an end cap 20. The shell 10 may be a metal shell, for example, made of aluminum. The end cap 20 may be provided with a positive electrode post 21 and a negative electrode post 22. The shell 10 may define a mounting slot with one end open. The end cap 20 is fixedly connected to the shell 10 and covers the opening of the mounting slot, so that the shell 10 and the end cap 20 jointly define a mounting cavity 30. The electrode assembly 300 of the battery cell 200 is installed in the mounting cavity 30. The shell 10 has a first wall portion 11 and a second wall portion 12 adjacent to each other. The shell 10 has a shell bottom wall 13, which is arranged opposite to the end cover 20 and spaced apart from the end cover 20. The shell bottom wall 13 is arranged adjacent to the second wall portion 12. The area of ​​the shell bottom wall 13 is smaller than the area of ​​the second wall portion 12. The shell bottom wall 13 is the narrow shell wall of the shell 10. The shell bottom wall 13 is constructed as the first wall portion 11, and the pressure relief portion 40 is arranged on the shell bottom wall 13.

[0230] In the above technical solution, by arranging the pressure relief portion 40 on the bottom wall 13 of the shell, the pressure relief effect of the battery cell 200 toward the bottom can be achieved, which can reduce the risk of high-temperature, high-pressure substances ejected from the battery cell 200 injuring surrounding personnel.

[0231] According to some embodiments of the present application, as shown in Figure 6, the housing 60 includes a shell 10 and an end cover 20, which are connected and jointly define a mounting cavity 30, and the shell 10 has a shell side wall 14 adjacent to the end cover 20, and the shell side wall 14 is configured as a first wall portion 11.

[0232] As shown in FIG6 , the housing 60 includes a shell 10 and an end cap 20 . The shell 10 may be a metal shell, for example, made of aluminum. The end cap 20 may be provided with a positive electrode post 21 and a negative electrode post 22 . The shell 10 may define a mounting slot with one end open. The end cap 20 is fixedly connected to the shell 10 and covers the opening of the mounting slot, so that the shell 10 and the end cap 20 jointly define a mounting cavity 30 . The electrode assembly 300 of the battery cell 200 is mounted in the mounting cavity 30 . The shell 10 has a first wall portion 11 and a second wall portion 12 adjacent to each other. The shell 10 has a shell side wall 14, which is adjacent to the end cover 20 and is also adjacent to the second wall portion 12. The area of ​​the shell side wall 14 is smaller than the area of ​​the second wall portion 12. The shell side wall 14 is the narrow shell wall of the shell 10. The shell side wall 14 is constructed as the first wall portion 11, and the pressure relief portion 40 is arranged on the shell side wall 14.

[0233] In the above technical solution, by arranging the pressure relief portion 40 on the shell side wall 14 , the battery cell 200 can be pressure-relieved laterally. During the pressure relief process of the battery cell 200 , high-temperature and high-pressure substances in the battery cell 200 can be quickly discharged from the battery cell 200 .

[0234] According to some embodiments of the present application, the present application further provides a battery 400 , comprising the battery cell 200 in the above embodiment.

[0235] According to some embodiments of the present application, the present application further provides an electrical device 500 , comprising the battery 400 in the above embodiment.

[0236] According to some embodiments of the present application, as shown in Figures 4 and 9, the present application provides a battery cell 200, which includes a housing 60 and an electrode assembly 300. The housing 60 includes a shell 10 and an end cap 20. The shell 10 and the end cap 20 are connected and together define a mounting cavity 30. The electrode assembly 300 is mounted in the mounting cavity 30, and the second wall portion 12 of the shell 10 is opposite to the straight area 301 of the electrode assembly 300. The bottom wall 13 of the shell 10 is configured as a first wall portion 11. A pressure relief portion 40 is provided on the bottom wall 13 of the shell 10. The pressure relief portion 40 is formed with a notched groove 41. The bottom of the notched groove 41 is formed with a first weak section 42 and a second weak section 43. The thickness of the second weak section 42 is less than the thickness of the first weak section 43. The first weak section 42 is a straight section extending along the second direction.

[0237] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0238] The difference between the battery cell 200 of the first embodiment and the battery cell 200 of the second embodiment is that the pressure relief portion 40 of the battery cell 200 of the first embodiment is eccentrically disposed, while the pressure relief portion 40 of the battery cell 200 of the second embodiment is disposed in the middle of the shell bottom wall 13 (i.e., the first wall portion 11). The difference between the battery cell 200 of the first embodiment and the battery cell 200 of the third embodiment is that the pressure relief portion 40 of the battery cell 200 of the third embodiment is disposed in the shell side wall 14. The difference between the battery cell 200 of the fourth embodiment and the battery cell 200 of the third embodiment is that the two electrical connection portions 23 of the battery cell 200 of the fourth embodiment are disposed on two opposing shell walls of the outer shell 60, and the pressure relief portion 40 is disposed in the middle of the shell side wall 14 (i.e., the first wall portion 11).

[0239] The pressure relief portion 40 of the first embodiment, the pressure relief portion 40 of the second embodiment, and the pressure relief portion 40 of the third embodiment differ in that the notched groove 41 of the pressure relief portion 40 of the first embodiment is annular, the pressure relief portion 40 of the second embodiment is a double Y-shaped structure, and the pressure relief portion 40 of the third embodiment is an I-shaped structure.

[0240] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0241] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and intent of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A battery cell, wherein, comprising: An electrode assembly including a positive electrode tab and a negative electrode tab. After the positive electrode tab and the negative electrode tab are stacked, a flat area is formed. At least a part of the positive electrode tab and at least a part of the negative electrode tab are stacked in the flat area along a first direction; A housing for accommodating the electrode assembly. The housing includes a first wall portion and two second wall portions connected to the first wall portion. The two second wall portions are respectively located on both sides of the flat area along the first direction; A pressure relief portion provided on the first wall portion. The pressure relief portion is formed with a scoring groove. The bottom of the scoring groove is formed with a first weak segment and a second weak segment. The thickness of the second weak segment is smaller than that of the first weak segment. The first weak segment is a straight line segment extending along a second direction, and the second direction is perpendicular to the first direction.

2. The battery cell according to claim 1, wherein, The pressure relief portion is configured to crack at the second weak segment when the internal pressure or temperature of the housing reaches a threshold value.

3. The battery cell according to claim 1 or 2, wherein, The scoring groove includes a first straight groove segment extending along the second direction. The first weak segment is formed at the bottom of the first straight groove segment.

4. The battery cell according to claim 3, wherein, The length dimension of the first weak segment is smaller than the length dimension of the first straight groove segment.

5. The battery cell according to claim 4, wherein, The ratio of the length dimension of the first weak segment to the length dimension of the first straight groove segment is greater than or equal to 0.5 and less than or equal to 0.

9.

6. The battery cell according to any one of claims 3-5, wherein, Along the second direction, the first weak segment is located at the middle position of the first straight groove segment.

7. The battery cell according to claim 6, wherein, The first weak segment is symmetric about the middle cross-section of the first straight groove segment, and the middle cross-section is perpendicular to the second direction.

8. The battery cell according to any one of claims 1-7, wherein, Along the depth direction of the scoring groove, the difference between the thickness dimension of the second weak segment and the thickness dimension of the first weak segment is greater than 0.05 and less than or equal to 0.45 mm.

9. The battery cell according to any one of claims 1-8, wherein, The scoring groove includes two first straight groove segments extending along the second direction. The first weak segment is formed at the bottom of each first straight groove segment.

10. The battery cell according to claim 9, wherein, The two first weak segments include a first segment and a second segment. The thickness of the first segment is smaller than that of the second segment. The pressure relief portion is configured that when the internal pressure or temperature of the housing reaches a threshold value, the first segment completely cracks and at least a part of the second segment does not crack.

11. The battery cell according to claim 10, wherein, The two first weak segments have equal lengths.

12. The battery cell according to claim 10 or 11, wherein, The scoring groove includes two first arc groove segments, and two ends of each of the first straight groove segments are respectively connected to the two first arc groove segments so that the scoring groove is configured in a ring shape, and a second weak segment is formed at the bottom of the first arc groove segment.

13. The battery cell according to any one of claims 1-8, wherein, the scoring groove includes a first straight groove segment extending along the second direction, and a first weak segment is formed at the bottom of the first straight groove segment.

14. The battery cell according to claim 13, wherein, the scoring groove includes a first straight groove segment and four second straight groove segments, two second straight groove segments disposed at a preset angle are respectively connected to two ends of the first straight groove segment, and a second weak segment is formed at the bottom of the second straight groove segment; or, the scoring groove includes a first straight groove segment and two third straight groove segments, the third straight groove segments are respectively connected to two ends of the first straight groove segment, and the third straight groove segment is perpendicular to the first straight groove segment, and a second weak segment is formed at the bottom of the third straight groove segment.

15. The battery cell according to any one of claims 1-14, wherein, along the second direction, the center of the pressure relief portion is offset from the center of the first wall portion.

16. The battery cell according to claim 15, characterized in that, along the second direction, the length dimension of the pressure relief portion is D, the distance between the center of the pressure relief portion and the center of the first wall portion is L, and the length of the first wall portion is E, satisfying the relationship: D / 2 < L < (E / 2 - D / 2) - 2.

17. The battery cell according to any one of claims 1-16, wherein, the pressure relief portion and the first wall portion are integrally formed; or, the pressure relief portion and the first wall portion are separately provided, the first wall portion is provided with a through hole, and the pressure relief portion is installed in the through hole.

18. The battery cell according to any one of claims 1-17, wherein, the outer shell includes: a housing and an end cap, at least one side of the housing has an opening, the end cap is connected to the housing and is used to close the opening, and the first wall portion is formed on the housing.

19. The battery cell according to claim 18, wherein, both opposite sides of the housing have openings, and the two end caps are used to close the corresponding openings.

20. The battery cell according to claim 18 or 19, wherein, the end cap is provided with an electrical connection portion, and the electrical connection portion is electrically connected to the positive electrode tab or the electrical connection portion is electrically connected to the negative electrode tab.

21. The battery cell according to claims 18-20, wherein, the first wall portion is used to support the electrode assembly and is located below the electrode assembly.

22. The battery cell according to any one of claims 1-21, wherein, the material of the outer shell includes at least one of aluminum, nickel-plated carbon steel, stainless steel, magnesium alloy, nickel alloy, copper alloy, and zirconium alloy.

23. The battery cell according to any one of claims 1-22, wherein, The positive electrode plate includes a positive current collector and the positive active material region disposed on the surface of the positive current collector, and the constituent material of the positive current collector includes aluminum element with a mass percentage of not less than 50%.

24. The battery cell according to any one of claims 1-23, wherein, the tensile strength of the first wall portion is not less than 400 MPa.

25. A battery, wherein, it includes the battery cell according to any one of claims 1-24.

26. An electrical device, wherein, it includes the battery according to claim 25.

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